Nonpoint source pollution:problems/solutions : proceedings, First Annual Virgin Islands Conference on Nonpoint Source Pollution, October 4-5, 1993/Department of Planning and Natural Resources, Coastal Zone Management Program.
Proceedings, First Annual Virgin Islands Conference on Nonpoint Source Pollution, October 4-5, 1993
Virgin Islands of the United States.Coastal Zone Management Program.
Virgin Islands Conference on Nonpoint Source Pollution(1st:1993:St. Thomas, V. I.)
St. Thomas, V.I.:The Program,[1993]
Nonpoint source pollution
Virgin Islands of the United States
Congresses.
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NONPOINT SOURCE POLLUTION
PROBLEMS/SOLUTIONS
PROCEEDINGS
FIRST ANNUAL ViRGIN ISLANDS CONFERENCE
on
* NONPOINT SOURCE POLLUTION
H
October 4-5, 1993
I.
DEPARTMENT OF PLANNING AND NATURAL SOURCES
COASTAL ZONE MANAGEMENT PROGRAM
TD ST. THOMAS, UNITED STATES VIRGIN ISLANDS
RoyE.
Adams, Commissioner
K
U EC1W
ACKNOWLEDGEMENTS
The First Annual Virgin Islands Conference on Nonpoint Source
Pollution would not have been possible without the generous support
of the sponsors listed on the Title Page. The Planning Committee is
grateful for the willing help from a number of persons: Lillian
Moolenaar and Fern LaBorde for handling the registration; Edelta
Webbe and Alma Wells for their advice on financial matters; Joan
Harrigan-Farrelly for advice on planning and Barbara Kojis for
editorial assistance.
Janice D. Hodge, Chairperson
Planning Committeee
U. S. DEPARTMENT OF COMMERCE NOAA
COASTAL SERVICES CENTER
2234 SOUTH HOBSON AVENUE
CHARLESTON, SC 29405-2413
LI1-,
t o'_ .§c .... VLib-R@
NONPOINT SOURCE POLLUTION
PROBLEMS /SOLUTIONS
October 4-5, 1993
SPONSORS
The Virgin Islands Department of Planning and Natural Resources,
* Coastal Zone Management Program
The University of the Virgin Islands,
Cooperative Extension Service and Eastern Caribbean Center
The Virgin Islands Resource Conservation & Development Council
The U.S. Environmental Protection Agency
The National Oceanic and Atmospheric Administration,
Office of Ocean and Coastal Resource Management
The U.S. Department of Agriculture,
Soil Conservation Service
U Virgin Islands Conservation District
PLANNING COMMITTEE
Janice D. Hodge, Chair/Coordinator
Julie Wright, Co-Chair
Olasee Davis
Bruce Green
Lynne MacDonald
Mario Morales
Algem Petersen
Marcia Taylor
TABLE OF CONTENTS
SECTION TITLE PAGES
PLENARY PRESENTATIONS I 1-26
URBAN SOURCES OF NONPOINT POLLUTION II 1-36
(LAND USE PLANNING AND CONSTRUCTION)
URBAN SOURCES OF NONPOINT POLLUTION III 1-44
(STORMWATER RUNOFF AND POLLUTION PREVENTION)
ONSITE SEWAGE DISPOSAL SYSTEMS (OSDS) IV 1-36
MARINAS, BOATING AND HYDROLOGIC MODIFICATION V 1-40
AGRICULTURE AND WETLANDS VI 1-24
WINNING STUDENT ENTRIES AND CLOSING REMARKS VII 1-8
The presentations in this collection were prepared camera-ready by the authors; they
have not been reviewed nor edited. This collection was compiled by Janice D. Hodge.
PLENARY PRESENTATIONS
Welcome Remarks
Honorable Alexander A. Farrelly, Governor I-i
Introduction
HOnorable Roy E. Adams, Commissioner . ..... ...*..... ....1-3
Territorial Rules andRegulations Governing Nonpoint Source
Pollution
Benjamin I. Nazario 1-5
Federal Rules and Regulations Governing Nonpoint Source
Pollution
Malcolm L. Henning .......1-9
Safeguarding Our Future Resources
I LaVerne Ragster.1-15
H i . Responsible Ecotourism Development
Stanley Selengut..** *.*.1-23
*per not available at time off printing
"I .
WELCOMING REMARKS
Honorable Alexander A. Farrelly,
Governor of the United States Virgin islands
commissioner Roy Adams, visiting guests and delegates, it is
a pleasure for me to welcome you to our First Annual Virgin
Islands Conference 'on Nonpoint Source Pollution. For those of
you visiting us for the first time, I hope you can take a few
moments from your busy schedule to enjoy what nature has
blessed us with. For those of you who are from here, Please
take some time to enjoy some of the beauty with our guests.
Nonpoint Source Pollution... what is it? If you are like me,
someone not used to the latest environmental jargon, you also
might be wondering what Non Point Source Pollution is. Over
the past year or so, I have heard the term mentioned numerous
times. I have been fortunate enough to have received a brief
description from my wife, 'the CZM Program Manager of the
Virgin Islands Department of Planning and Natural Resources.
I now know that these pollutants, which are an everyday part
of our lives affect each of us on a personal level. Rainwater,
seems harmless enough and something we all need. However,
rainwater picks up pollutants from our well kept lawns, from
our streets and farms and from construction sites. It is
carried into our wetlands and oceans as well as our ground
water. These days, I cannot look at the rain falling and enjoy
it, because I now think of its effects as it cascades down the
I. mountainsides and roads, wondering what is being picked up and
where it will be deposited.
Construction practices also contribute to the degradation of
our coastal waters and drinking water. A degraded ocean means
a reduction or elimination of our fish habitats, degraded
coral reef systems, and a reduction in plant populations.
Cloudy polluted waters, also mean a reduction in recreational
activities, since no one wants to swim in unsafe, unappealing
* waters.
Today's conference, ,Non Point Source Pollution, Finding
Solutions to Environmental Pollution", gives us all an
opportunity to learn more about the problem. But even more
important it enables us to come up with solutions. However, a
two day conference can only begin to scratch the surface. I
commend Commissioner Adams and the CZM Program for taking the
f irst step in bringing these issues to the forefront for us to
give them deep thought, and I hope all of us, particularly
those in the building trades, and in agriculture, as well as
all of our Government Departments, take heed and begin to plan
their activities with this new awareness.
My administration has always been and continues to be
committed to ensure our waters are clean, our beaches remain
beautiful and we all enjoy a healthy environment. Through the
Department of Planning and Natural Resources, we continue to
put in place the mechanisms for managing, enhancing, and
protecting our natural resources and coastal areas.
Last week, the CZM Commission voted to approve 'management
plans for eighteen Areas of Particular Concern (APC's). This
was no easy feat, and I wish to commend all those involved in
this effort. The management plans and boundaries are being
reviewed by my office, and will be forwarded to the
Legislature for their approval and adoption. But, because the
Senate is currently absorbed in consideration of the Fiscal
year 1994 budget of the Virgin Islands, I requested they
extend the time frame for their final approval of the 18
APC's. Deliberating over the budget is a process that is
likely to extend to December. It is my belief a date of
January 31, 1994, for APC approval is realistic and fair.
Our Land and Water Use Plan, our Territorial Park System, are
all part of a major effort in ensuring a continuation and an
enhancement of what we all call " Paradise." If we all commit
ourselves to work together for the good of our beautiful
islands, we can still preserve and protect the good we have.
Again, I welcome you to the conference, and I hope the
information we share here will be of practical use to us all.
Thank you.
..
, 7 ,.
-"114 A ,
INTRODUCTION
Honorable Roy E. Adams, Commissioner
Department of Planning and Natural Resources
As part of the Coastal Zone Act Reauthorization Amendments of
1990, Congress enacted a new section 6217 entitled "Protecting
our Coastal Waters.". This provision requires states with
coastal zone management programs that have received Federal
approval under section 306 of the Coastal Zone Management Act
to develop and implement coastal nonpoint pollution programs.
Because the coastal nonpoint pollution control program must be
approved by the Environmental Protection Agency (EPA) and the
National .Oceanic and Atmospheric Administration (NOAA) , the
Virgin Islands, as well as all other territories and states,
must comply with mandates set forth by these federal agencies.
Some of these mandates will require statutory changes in the
VI code in order to make our program acceptable.
A Virgin Islands Nonpoint Source (NPS) Pollution Committee
consisting of federal, territorial and local agencies has been
established to address nonpoint source pollution. The
Committee will review the various mandates of EPA and NOAA as
they pertain to the virgin Islands and develop and implement
Best Management Practices (BMPs) to control NPS pollution.
At this point in their progress, the NPS Committee finds it
necessary to conduct this conference so that information about
nonpoint source pollution can be shared with the public.
Through this conference we hope to provide the general public
and specific groups, such as contractors, architects, farmers
and marina operators with sufficient information so that they
can begin to focus on the various methods by which they can
each reduce or eliminate nonpoint source pollutants and so
help to satisfy the requirements of the nonpoint source
pollution control program. It is very important for us to have
the full participation of all concerned as early in the
development of this program as possible so that any
amendments to the existing VI code or program recommendations
will have the necessary cooperation of all who will be
affected.
We do realize that nonpoint source pollution cannot be
eradicated within a year or two. Effective management of NPS
pollution is essential to maintain the high water quality that
currently exists in the virgin Islands. The major sources of
pollutants that impair our waterbodies are erosion and
sedimentation from site development, urban runoff, vessel
wastes disposal, and failing septic systems.
1-3
As you will discover when you attend the various
presentations, nonpoint source pollution impacts our
environment in many ways. Loss of fishing, loss of habitat
(for some endangered species), human health risks, and loss of
tourism - our primary industry are just a few.
Because of the importance of our natural resources to our
economy, and because we all strive for a clean healthy
environment, it is imperative that we begin to address our
environmental problems now. We in the Virgin Islands enjoy an
environment that isg far superior to many others, let us do
what we can now, while we still have a chance, to maintain it
and where possible improve it. Keep in mind that the purpose
of this conference is to share ideas and information so that
we can work cooperatively to maximize our efforts.
TERRITORIAL RULES & REGULATIONS
GOVERNING NONPOINT SOURCE POLLUTION
Benjamin I. Nazario
Division of Environmental Protection
Virgin Islands Department of Planning and Natural Resources
Non-point source is defined as pollution sources which are diffuse and do not have a single
point of origin or are not introduced into a receiving stream from a specific outlet. The
pollutants are generally carried off the land by stormwater runoff. The commonly used
categories for non-point source are: agriculture, forestry, urban, mining, constructions, dams
and channels, land disposal, and saltwater intrusion.
The first opportunity and consideration in any non-point source effort is source control.
By their nature laws and regulations are normally addressed at a specific source. The Virgin
Islands laws that are affected in the control of non-point source pollution are part of Titles
12, 19 and 29 of the Virgin Islands Code and its rules and regulations and are as follows:
TITLE 12 CONSERVATION:
CHAPTER 3 "TREES AND VEGETATION ADJACENT TO WATERCOURSES"
Establishes policy for the cutting or injuring of certain trees within certain confines
to a watercourse and institutes a permit requirement for said activity and provides for
enforcement by DPNR Environmental Enforcement Officers. Permits are issued by the
Commissioner of the Department of Planning and Natural Resources (DPNR).
CHAPTER 5 "WATER RESOURCES CONSERVATION"
Establish policy and regulations for the protection, conservation and development of
the water resources, both surface and underground water of the U. S. Virgin Islands.
Applications and plans for groundwater use are reviewed and permits issued by the Division
of Environmental Protection (DEP) of DPNR.
CHAPTER 7 "WATER POLLUTION"
Establish policy and regulations to conserve the waters of the VI, to protect and
maintain, and improve the quality thereof for public water supplies, for propagation of
wildlife, fish and aquatic life, and for domestic, recreational and other legitimate beneficial
uses; to provide that no waste be discharged into any waters of the VI without first
receiving necessary treatment or corrective action to protect the legitimate beneficial use
of such water; to provide for the prevention, abatement and control of new or existing
water pollution; to authorize the implementation of the Federal Water Pollution Control
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NON-POINT SOURCE POLLUTION CONFERENCE
St. Thomas, U.S. Virgin Islands
Territorial Rules and Regulations Governine Nonooint Source Pollution
Act (FWPCA) and other amendatory acts.
Territorial Pollution Discharge Elimination System (TPDES) - a system of
requirements to obtain permits for commencement or continuation of any discharge of
pollutants to surface waters. Applications and plans are reviewed and permits issued by
DEP.
Water Quality Certification (WQC) - Certifications are issued by DEP.
This chapter needs to be revised and updated to address the federal requirements
of the National Storm Water Program which complements the TPDES permit system. The
system focuses on the municipal and industrial pollution prevention to help control storm
water pollution and involves issuing permits to certain municipalities and industries to
control storm water pollution.
CHAPTER 13 "ENVIRONMENTAL PROTECTION"
Earth Change plans and permits required before any real property is cleared, graded,
filled or otherwise disturbed for any purpose or use including but not limited to erection of
any building or structure, the quarrying of stone or the construction of roads and streets.
Plans are reviewed and permits issued by the Permits Division of DPNR.
CHAPTER 17 "OIL SPILL PREVENTION & POLLUTION CONTROL"
Establish policy to regulate the transfer, storage and transportation of pollutants and
other such products that pose threat of great damage and damage to the environment, to
owners and users of shore front property, to public and private recreation, to citizens of the
territory and other interests deriving livelihood from marine related activities and to the
beauty of the territorial shoreline. The provisions of this chapter are administered by DPNR.
This statute and its rules and regulations need to be revised and updated to include
the requirements of the Oil Pollution Act of 1990, the Underground Storage tank (UST) and
Above-ground Storage Tank (AST) provisions.
CHAPTER 19 "PESTICIDE"
Establishes policy to regulate the use and application of pesticides to control pests.
Pests are defined as any insect, rodent, nematodes, fungus weed or any other form of
terrestrial or aquatic plant or animal life or virus, bacteria, or other microorganisms (except
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NON-POINT SOURCE POLLUTION CONFERENCE
St. Thomas, U.S. Virgin Islands
Territorial Rules and Regulations Governinf Nonvoint Source Pollution
viruses, bacteria, or other microorganism on or in living man or the living animals) which
is declared by the Commissioner. Provision of this chapter are administered by DPNR.
Certification is issued by the Division of Environmental Protection (DEP) of DPNR.
This statute and its rules and regulations need to be revised and updated.
CHAPTER 21 "COASTAL ZONE MANAGEMENT ACT"
The Coastal Zone Management Act (CZM) mandates by policy to protect, maintain,
preserve and where feasible enhance and restore the overall quality of the environment; to
provide economic development and growth; to assure orderly balanced utilization and
conservation of resources, etc., to conserve ecologically significant resource areas, and
preserve the function and integrity of reefs, marine meadowlands, saltponds, mangroves and
other significant natural areas; to maintain or increase coastal water quality through control
of erosion, sedimentation, runoff siltation and sewage discharge. Applications and plans are
reviewed by the Permits Division of DPNR and permits are approved by the island CZM
Committee or the Commissioner of DPNR depending on whether the application is for a
major or minor permit.
TITLE 19 HEALTH:
CHAPTER 53 "SANITATION"
Provides policy for the regulation of discharges from building or premises to existing
sanitary sewers or public sewers; the contents of cesspools or septic tanks into public gutters;
the collection and/or treatment of refuse deposition of materials or waste products that
cause the surrounding air, land or water to be contaminated or polluted in such a manner
as to injure public health; design, location and installation of sewage treatment systems.
This statute and its rules and regulations need to be revised and updated. Applications and
plans are reviewed and permits issued by DEP.
CHAPTER 55 "SEWAGE DISPOSAL"
Establishes policy to regulate design, location and installation or sewage disposal
systems. Institutes a Sanitary Facilities Fund and promulgates the collection of fees for the
use of the public sewer system.
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NON-POINT SOURCE POLLUTION CONFERENCE
St. Thomas, U.S. Virgin Islands
Territorial Rules and Reulations Governine Nonooint Source Pollution
CHAPTER 56 "SOLID AND HAZARDOUS WASTE MANAGEMENT" I
Establishes policy and regulation for the proper storage, transportation and disposal
of solid and hazardous waste in the Virgin Islands; to promote and facilitate, wherever
possible, resource conservatiQn and recovery; to impose the duty of contribution to public
cleanliness and appearance in order to promote public health, safety and welfare. this
chapter provides for the proper disposal of derelict vehicles.
This chapter is presently being revised and up dated to reflect the requirements of
the new federal landfill criteria.
TITLE 29 PUBLIC PLANNING AND DEVELOPMENT:
CHAPTER 3 "VIRGIN ISLANDS ZONING AND SUBDIVISION"
Establishes standards and policies concerning development of land which may be
used in achieving the goals of the General Development Plan of the Virgin Islands. the
purpose is to promote health, safety, ,morals and general welfare of the community by
establishing regulations and conditions governing the erection of buildings, structure and use
of land and water.
CHAPTER 5 "BUILDING CODE"
Establishes policy and regulations to safeguard life and limb, property, and public
welfare, through the establishment of minimum building requirements for structural strength
and stability. Has specific provisions for flood control and protectionsanitary sewage
systems, etc. Plans are reviewed and permits issued by the Permits Division of DPNR.
All of these statutes and Rules and Regulations are of the 1970's vintage. They require
revision and updating to reflect present amendments and state of the technology. We in
DEP are present working to address some of these short comings for instance we're working
to revise the Pesticides laws, the solid waste to comply with the federal laws for landfills, the
Air pollution laws to comply with the Clean Air Act of 1990, the Oil Pollution Act 1990.
Non-Point Source Program - DEP is presently working with the VI Soil Conservation
District on a project partially funded by EPA to study storm water and septic tank
regulations.
Federal Rules and Regulations Governing Nonpoint Pollution
Malcolm L. Henning
U.S. Environmental Protection Agency, Region II
New York, New York
In 1987 when Congress amended the Clean Water Act (CWA), it
was clear that one of their goals was to establish a
national policy on the control of Nonpoint Source (NPS)
pollution and that a national Nonpoint Source pollution
control program be developed and implemented in an
expeditious manner so as to enable the goals of this Act to
be met thrpugh the control of both point and nonpoint
sources of pollution.
Section 319 of the Clean Water Act, is the national program
enacted by Congress to control nonpoint sources of water
pollution.
Section 319 required two major reports to be completed by
the States/Territories: A state/territory Assessment Report
describing the State's NPS problems and a state/territory
Management Program explaining what the state plans to do in
the next four fiscal years to address their NPS problems.
The U.S. Virgin Islands has an EPA approved Assessment
Report and Management Program.
What is Nonpoint Source Pollution?
For the purpose of implementing the NPS provisions in the
CWA, NPS pollution is defined as follows:
Nonpoint Source Pollution: NPS pollution is caused by
diffuse sources that are not regulated as point sources and
normally is associated with agricultural, silvicultural and
urban runoff, runoff from construction activities, etc.
Such pollution results in the human-made or human-induced
alteration of the chemical, physical, biological, and
radiological integrity of water. In practical terms,
nonpoint source pollution does not result from a discharge
at a specific, single location (such as a single pipe) but
generally results from land runoff, precipitation,
atmospheric deposition, or percolation. It must be kept in
mind that this definition is necessarily general; legal and
regulatory decisions have sometimes resulted in certain
sources being assigned to either the point or nonpoint
source categories because of considerations other than their
manner of discharge. For example, irrigation return flows
are designated as "nonpoint sources" by Section 402(1) of
T-9
the Clean Water Act, even though the discharge is through a
discrete conveyance.
Examples of NPS Pollution
1 NonDoint Sources 70 Hvdroloalc/Habitat Modification
71: Channelization
10 Agriculture 72: Dredging
11: Non-irrigated crop production 73: Dam construction
12: Irrigated crop production 74: Flow regulation/
13: Specialty crop production (e.g., modification
truck farming and orchards) 75: Bridge construction
14: Pasture land 76: Removal of riparian
15: Range land vegetation
16: Feedlots, all types 77: Streambank modification/
17: Aquaculture destabilization
18: Animal holding/management areas
20 Silviculture 80 Other
21: Harvesting, reforestation, 81: Atmospheric deposition
22: Forest management 82: Waste storage/storage tank
23: Road construction/maintenance 83: Highway maintenance and
runoff
30 Construction 84: Spills
31: Highway/road/bridge 85: In-Place contaminants
32: Land development 86: Natural
40 Urban Runoff 90 Source unknown
41: Storm sewers (source control)
42: Combined sewers (source control)
43: Surface runoff
50 Resource
Extraction /Exoloration /DeveloDment
51: Surface mining
52: Subsurface mining
53: Placer mining
54: Dredge mining
55: Petroleum activities
56: Mill tailings
57: Mine tailings
60 Land Disposal (Runoff/Leachate From
Permitted Areas}
61: Sludge
62: Wastewater
63: Landfills
64: Industrial land treatment
1-10
65: On-site wastewater systems (septic
tanks, etc.)
66: Hazardous waste
Nonpoint Source Financial Provisions
The CWA of 1987 provides four new sources of funds in the
CWA, on an annual basis, to support the implementation of a
State's nonpoint source Management Program.
(1) Section 319(h) authorize grant funds to support
protection of both surface and ground water quality.
These funds are not to be used as a general subsidy or
for cost sharing to support implementation of best
management practices by individuals, except for
demonstration purposes.
(2) Section 205(j)(5) provides a set-aside of 1% of
each State's annual construction grant allocation or
100,000, whichever is grater, to be used for the
preparation and implementation of the State's
management program. Section 205(j) (5) funds are now
provided under Section 604(b) funding requirements.
(3) In addition, nonpoint source control efforts may be
financed thought the Governor's 20% discretionary set-
aside of construction grant funds under amended section
201(g) (1).
(4) Finally, new State revolving funds established by
Title VI may be used for loans, including loans to
public agencies or individuals, to implement NPS
management programs, for instance, 601 and 603 water
pollution Control funds.
The use of each funding source is subject to certain
statutory restrictions and limitations. The flow of Federal
funds in support of State management program activities
under section 319 is conditioned based on the EPA aDDroval
of the State's Manaaement Proaram. The single exception to
this rule are funds set-aside from construction grant
allocations under Section 205(j)(5). These funds may be
used to develop the management program and then, later, to
help implement the State's management program.
The Federal share of implementing a nonpoint source
management program under Section 319(h) shall ot exceed 60%
in any fiscal year. Section 319(h) funds may not be awarded
unless the State has demonstrated satisfactory progress in
meeting the schedule set out in the approved nonpoint source
management program.
In addition to Section 319, the Clean Water Act of 1987 also
included Nonpoint Source provisions in other CWA programs.
I-lI
Section 314 Clean Lakes Program is to protect the quality of
the country's publicly owned freshwater lakes by controlling
sources (point or nonpoint) of pollution affecting them and
by restoring lakes which have deter/orated in quality.
Lakes are funded under three mechanisms. They are:
1. State Lake Classification Study: The state classifies
by trophic condition all its publicly owned freshwater lakes
needing restoration-and protection. Then the state lists
these lake projects in order of priority. Funding
assistance may go to $100,000 or 70% of the cost.
2. Phase I Diagnostic Feasibility Study: This study
determines the cause of the lake problems, evaluates
possible solutions, and recommends the most feasible program
to protect and restore the lake's quality. Again, the
funding assistance is 70% federal and 30% territory or
local, to a maximum of $100,000.
3. Phase II Implementation: The implementation phase put
the recommendations into operation. The funding of phase II
is 50/50, however, the state/local share can include in-kind
services.
Section 320 National Estuary Program is to restore and
maintain the chemical, physical, and biological integrity of
an estuary by addressing both point and nonpoint sources of
pollution.
The Governor of any state/territory may nominate to the
Administrator of EPA an estuary of national significance and
request that a management conference develop a comprehensive
management plan for the estuary.
Other Federal Rules and Regulations Governing Nonpoint
Source Pollution.
We have talked a little about the Section 319 Nonpoint
Source program and other Sections under the CWA, now I will
discuss some of the other federal laws that governs Nonpoint
Source pollution.
1. The Safe Drinking Water Act of 1984: The Safe Drinking
Water Act required that national standards be-established
for drinking water. The law requires two things for all
community drinking water systems: (a) Routine monitoring
for several pollutants, and (b) Compliance with minimum
standards. The Environmental Protection Agency (EPA) is
required to set standards for 100 pollutants, including
several toxic chemicals.
2. EPA Stormwater Runoff Rules and Regulations of 1990:
This program is known as the National Pollutant Discharge
I-12
Elimination System (NPDES) which was amended by Congress in
the CWA of 1987. The amendment required EPA to establish
phased NPDES requirements for storm water discharges. To
implement these requirements, EPA published-the initial
permit application requirements for certain categories of
storm water discharges associated with industrial activity,
and discharges from municipal separate storm sewer systems
located in municipalities with a population of 100,000 or
more.
3. The Pollution Prevention Act of 1990: The pollution
Prevention Act identifies pollution prevention as EPA's
environmental management approach of choice, and requires
the incorporation of pollution prevention into EPA
activities beginning in the Federal Fiscal Year (FFY) 1994
State/territory grants cycle.
4. The Coastal Zone Act Reauthorization Amendment of 1990:
This amendment was intended to strengthen the links between
Federal and State coastal zone management and water quality
programs and enhance State/Territory and local efforts to
manage land use activities that degrade coastal waters and
coastal habitat. States/Territories with approved coastal
management programs are required to develop Coastal.Nonpoint
Pollution Control Programs. The programs must be submitted
to EPA and NOAA for approval. The coastal nonpoint
pollution control programs will be implemented through both
State coastal zone management programs and State NPS
management programs.
5. The Federal Intermodal Surface Transportation Efficiency
Act of 1991: The Federal Intermodal Surface Transporation
Efficiency Act (ISTEA), established the Surface
Transporation Program (STP). ISTEA also created a
transportation enhancement activities program as a component
of STP. Ten percent (10%) of the' funds apportioned to a
state for the STP is only available for these enhancement
activities. Eligible transportation enhancement activities
consist of the following:
* Provision of facilities for pedestrians and bicycles
* Acquisition of scenic easements and scenic or historic
sites
* Scenic or historic highway programs
* Landscaping and other scenic beautification
* Historic preservation
* Rehabilitation and operation of historic transportation
buildings, structures or facilities including historic
railroad facilities and canals
* Preservation of abandoned railway corridors including
the conversion and use thereof for pedestrain or
bicycle trails
* Control and removal of outdoor-advertising
* Archaeological planning and research
* Mitigation.of water pollution due to highway runoff
6. USDA 1990 Farm Bill'or the Food, Agriculutre,
Conservation and Trade Act of 1990: This farm programs law
reinforces USDA commitment to protecting the nation's
natural resources. It expands the conservation provisions
under the Food Security Act of 1985. It encourages the
reduction of soil erosion, the retention of wetlands and
protection of other environmental sensitive cropland. The
provisions include:
(a) Conservation Compliance: Discourages the production
of crops on Highly Erodible Lands (HEL) cropland unless the
land is protected from erosion under an approved
conservation plan or system. The plan or system must be
fully implemented by December 31, 1994.
(b) Sodbuster: Discourages the production of crops on HEL
lands that was not used for crop production between 1981 -
1985 unless the land is protected from erosion under an
approved plan or system. The plan or systems must be fully
implemented before crops can be planted on the HEL land.
(c) Swampbuster: Discourages the alteration of wetlands
for agricultural purposes.
(d) Conservation Reserve Program: Offers long-term rental
payments and cost-share assistance to farm owners or
operators to establish permanent vegetative cover for land
that is HEL or contributing to a serious water quality
problem.
(e) Wetlands Reserve Program: A voluntary USDA easement
program to restore and protect wetlands.
7. The Clean Vessel Act of 1992: Although this is not a
NPS federal law, it is a Federal law that you may want to
become familiar with. This law allows States to apply to
the U.S. Fish and Wildlife Service for grant funds to
construct pump out stations and waste reception facilities.
A total of 12.5 million was made available during the first
open period ending on August 31, 1993.
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SAFEGUARDING OUR FU7TURE RESOURCES
da Verne B. Ragster
Eastern Caribbean Center, University of the Virgin Islands
St. Thomas, US Virgin Wsands 00802
There is a growing school of thought that says there will be poor, or no
prospects for the future of humanity and the world's natural resources if
individuals, communities, and governments do not quickly begin to
recognize that conservation and development are essential parts of one
indispensable process. This would mean the challenge implied in the title
of this talk is the need to change (where necessary) attitudes and
behaviors of people at all levels of organization. This change is
necessary to realize development that concentrates in an integrated
fashion on improving the human condition and maintaining the diversity and
productivity of nature. Caring for the Earth (7) describes a strategy or
guide for achieving sustainable societies and proposes this solution as
the rational option open to humanity.
The nine principles proposed for a sustainable society are not new to some
cultures of the world, but they would require significant changes in the
behavior of people and institutions in most societies today. The
principles are based on the need for cooperation and caring among people,
on the acknowledgment of limits in nature, and on an ethic that recognizes
nature has to be cared for in its own right, not just as a means of
satisfying human needs. The deliberations that will occur at this
conference run the risk of being self -serving to a small part of society -
the converted speaking to the converted for reassurance. It would also
miss an opportunity to move the US Virgin Islands ahead in its quest for
a rational future, if the principles listed below (or some other similar
conceptual guide) are not used as benchmarks for a code of belief and
proposed actions.
A world Conservation Strategy
Princioles of a Sustainable Society (7)
1. Respect and care for the community of life.
2. Improve the quality of human life.
3. Conserve the Earth's vitality and diversity.
4. minimize the depletion of non-renewable resources.
5. Keep within the Earth's carrying capacity.
6. Change personal attitudes and practices.
7. Enable communities to care for their own environments.
S. Provide a national framework for integrating development and
conservation.
9. Create a global alliance.
The aforementioned principles imply that the existence and good health of
future natural resources of the Virgin Islands require present-day efforts
to focus on dialogs and actions which result in the Virgin Islands
community living sustainably. Clearly, this is no small challenge for an
urbanized, multi-cultural political dependency with a small land mass, a
high population density, mass tourism as the main economic activity, and
limited, vulnerable natural resources. The USVI has begun to address the
changes necessary to view and implement development and conservation as
part of the same process, but- like most of the rest of the world, we have
much to do to make discussions and small initiatives toward sustainable
development grow into a way of life.
it is useful at this point to share two versions of the definition of
sustainable development.
Sustainable development is:
a) improving the quality of human lif e while living within the
carrying capacity of supporting ecosystems (7); and it also is
b) a process in which qualitative development is maintained and
prolonged while quantitative growth in the scale of economy becomes
increasingly constrained by the capacity of the ecosystem to perform
over the long run two essential functions. to generate the raw
material inputs and to absorb the waste outputs of the human economy
(2) .
it follows from these definitions that a sustainable economy becomes the
product of sustainable development. Then, it is logical that a
sustainable economy must maintain its natural resource base and continue
to develop by adapting and improving using knowledge, organization,
technical ef ficiency and wisdom. Therefore, one of the challenges to the
realization of a sustainable economy is the increasing levels of pollution
(in the world) which impact human and environmental health in a negative
manner. in the waters surrounding the Caribbean archipelago, wastes
produced continuously and often imperceptibly by land-based activities,
contaminate and adversely impact marine ecosystems (and the
health of marine resource users) . The most evident sources of this
nonpoint pollution in the region include (14): agriculture and forestry;
construction works; urban run-off; atmospheric fall-out, ground water
seepage; oil and other chemical spills and disposal; solid-waste disposal
and its leachates; sub-surface disposal of sewage and other wastes; andI
Today we live in a world where some economists argue that pollution
control involves establishing a balance between the use of the environmentI
for waste disposal and its use for all other purposes (5) . The conflicts
that often result among the different parties concerned with pollution of
an area or resource have helped to foster the development of policies and
mechanisms (from a number of conceptual frameworks - mostly rooted inI
economic theory) for conflict resolution and prevention of pollution. The
USVI has benefited from this ongoing process. However, there is still a
need to customize mechanisms for prevention and control. Therefore, the
formulation and implementation of policy on pollution prevention andI
control appropriate for the USVI would be assisted by considering some of
the questions that pertain to 'safeguarding future resources, within the
context of achieving sustainable development in the territory.3
The determination of the types and levels of reso urces that should be
protected for the future is tied to the environmental ethic we accept and
practice. The list of natural resources (including habitats) we believe
should be protected or conserved would probably be most diverse and mostI
numerous if we agreed that all natural resources have intrinsic value. on
the other hand, if other organisms have no rights to life and their
"purposeu on the planet is to be fully exploited for human derived
benefits, we are likely to have low numbers and kinds of resourcesI
available.
The natural resources in the USVI that are viewed as having high value, as
is the case in much of the Caribbean region, include marine ecosystems - I
coral reefs and seagrass beds; coastal ecosystems - mangrove forests and
lagoons and salt ponds; and terrestrial ecosystems - dry to moist
evergreen and rain forests, especially those associated with watersheds.
(Refer to Table 1.) The value of these resources as habitats, as food andI
raw materials sources, as structural protection and as contributors to the.
quality of life continues to be demonstrated and studied. The question is
whether we want to pass an some, all, or none of these resources and their
value to future generations.I
Another part of the question relates to the condition or health of the
resources that are available to future societies. Ecosystems found in the
1-16
-------
virgin Islands and other Caribbean islands are usually connected to each
other and surrounding human built systems through the movement of water,
air and organisms. (Ref er to Figure 1.) Hence, pollutants and disease
vectors can move with energy and materials between systems in an
opportunistic manner, to the detriment of the physical and biological
capacity and diversity of the impacted areas. This situation presents a
major challenge to management of these areas and the control of pollution,
especially with regard to nonpoint sources of pollution. Consequently, an
exploration of "safeguarding of resources must address current activities
of human societies and their potential to influence the health and
stability of natural resources.
The question of who is to be responsible for the type and level of
international attention. An increasingly popular position is thatscea imac on atrl esuesi oetht as eevd
sustainable society will depend on new partnerships of local people,
citizens, groups, businesses and governments. in this case, it is
essential to have early substantive input by partners into development
plans which strive to be equitable, sustainable, practical, sensitive to
local norms and cultures, and are welcome to the people concerned. The
implication here is that everyone has a stake and an opportunity in the
process of addressing the management and conservation of natural
resources. Clearly, there would be a need for information on the resource
and its current or potential uses and users, open dialog between partners,
and new roles in research, monitoring and management for various partners.
The skills needed to undertake the group dynamics associated with multi-
disciplinary teams and innovative problem-solving will have to be crucial
elements of the training of citizens, politicians, urban and rural
managers, as well as of educators and other professionals. Therefore, the
answer to who will safeguard our future resources should be everyone who
could possibly help - all of us.
Suggestions and recommendations concerning steps that should be taken to
move Caribbean societies toward sustainable living have come from many
individuals and groups, including many at the regional and international
levels. The nine principles of the World Conservation Strategy (1980)
developed by the United Nations Environment Programme (UNEP), The World
conservation union (IUCN), and world wildlife Fund (WWF), have already
been mentioned, and are mirrored in the outputs of the United Nations
conference on Environment and Development (UNCED) - Agenda 21, the
Biodiversity Convention, the Framework Convention for Climate Change, and
the Declaration of Principles on Forests. within the region, the Port of
Spain Accord on the management and Conservation of the Caribbean
Environment (1989), The Caribbean Action Plan of the Caribbean Environment
Programme (1981) and the Report of the West Indian Commission - Time For
Action (1992), have all presented concerns and strategies related to the
implementation of sustainable development in the region.
Generally, the following approaches (modified from the Port of Spain
Accord) are included in strategies proposed as appropriate ways to
address present development challenges and the achievement of sustainable
societies.
a) Provision of training and the development of human Resources
to produce appropriately trained professionals and experts as well
as an informed and active citizenry.
b) Collection, management and dissemination of information
requredfor policy formulation and decision-making within the
conceptual framework of sustainable development.
c) Formulation of policies and plans that integrate
economic, social and environmental issues through the use of
interdisciplinary teams at all levels.
I-17
d) Development of legal frameworks and institutional arrangements
which facilitate environmental management and rational development.j
e) Promotion of economic pursuits which acknowledge and respond
to environmental parameters and limits.
f) inclusion and harnessing all available political,
institutional and community-based resources in the process of
development and problem-solving for society.
Locally, the Comprehensive Water and Land Use Plan , the development of 18I
Areas of Particular Concern under the Coastal Zone Management Program, and
legislation related to endangered species and the Territorial Park System
identify and begin to shape the Virgin islands, vision of living
sustainably. When the discussions at the local and regional levelsI
concentrate on pollution as an issue, the specific recommendations for a
strategy include a) pollution prevention methods, b) ef fluent limitations;
c) water quality limitations; d) environmental planning; and e) the use of
best management practices (6)'.
Clearly, there are gaps and areas of weakness that must be confronted if
reality in the future is to match the vision of the territory and the
region. Three major concerns are the establishment of policies and groups
of people and/or institutions which will facilitate 1) the integration of
economic, social and environmental planning within a framework that
specifically addresses sustainability; 2) the development of mechanisms
which will more effectively incorporate various interests of Virgin
islands society into planning and management associated with development;
and 3) the formulation of education and awareness programs (formal and
informal) that would provide everyone with the appropriate conceptualI
framework and the problem-solving and group dynamic skills needed to
individually construct and implement a sustainable lifestyle.
implementation of strategies to address these concerns, challenges
governments and institutions in the Virgin islands and the region toI
significantly adjust institutional attitudes and arrangements as well as
the way funds are currently directed.
A reminder is perhaps appropriate at this point. we humans have a
difficult time accepting and implementing change, especially the far-
reaching type proposed in the concepts of sustainable development. The
recommendations made require all of us to re-examine our values and alter
our behavior - at the'individual and institutional levels. Hence, anyI
negative (physical or mental) responses you may experience in reaction to
ideas mentioned concerning sustainable living may be signs of personal
discomfort with the idea of change. it is my sincere hope that over time
the dissemination of information and guidance through formal and informalI
education activities, as well as incentives from society to make changes
in how we address development, will move us to formulate and implement the
policies and systems needed for the survival of our natural resources,
ourselves and our society.I
How we handle nonpoint pollution today will be one of the determinants of
whether the next generations of Virgin islanders have thriving coral
reefs, watersheds with clean ground water, healthy versions of Magens BayI
and Trunk Bay, populated seagrass beds in the inshore waters of St. Croix
and a functional mangrove lagoon an St. Thomas to manage and enjoy. The
challenge to us concerning the safeguarding of future resources must be
confronted within the context of resolving our development and quality ofI
life issues as we strive to achieve a sustainable society.
I-18
Figure I -Erosive Energy Buffer Systems an Islands
rswt
n
fodbfe
s y c ,Tcn c st nenr s m su g
Sars
-nao
mao C
Re
1-19
Table I -Ecosystemns Present an the U.S..Mflllated Islands Table 1 -tomystoem Preasent an 11% U.S-Afftllstse lsusd-Contnued
Fecerstec 1Stalof M lome
a Areas Pueno Alco USI A AOmeeCa Seas Glush CHUIm Paeltalu Kegree D ornm yoTnik
0forest PreseM nt May hae" DMe UnaIdwea Ulornta Possibl an too of Mourn racscanau. None None Present an Mnountain Al htietim- el5 m one None
-vuPtmm foI arsnt lon a on on ofac TWO Mountl L-erntu Smoul; otherI.to is-od
mou intWes i smlns unknon Nnit.om At aftlo fr Almcetvtosmmunt ma-o
Mmentas rawn otivteri an signer None Mlceolievulo nag" None None Nonematt aiiIO rtoi'elOiI l tfva e None Um as on ta
a t -eownios amnon satosery mtsauws
grognithP-a oatmn o amo semeoghmP t" itar
end rmesitoret -:tIe remain Nons Atmi*naon steso Sceered remains of Laws forest on nonn- N O"l Lilftt5Uw ,Peetat*ay rsn otmn See-re oe. ret Mne
samas irnetone. eSotes- anm Istlica mi en "c amessaiy un,-:etwaftod o tgno aeKWs
inS"Sitandce.ic - ?,iiefl cinte Man* Lmiteo flaamunt Present alon fryvers. in lraines$ an smaller 'lone twinfoq meets * Al"ng Wmer Ino Un-t OM, Songmee. Powresen nlater of Present, INtn of
streasul most ly in South
too" 1C noet - :.Is remaints jmitec areas in Non* Nonle None Nhe'ano None 'Oftneone None
Om (of I N avyeamo e
fl5 5ff "nt o -fl tiU1 Presenht, considera- sscNone Nona Nth" .11 4"0 n None Nane
it :' -qlnuI ecosystem bly reotaceO from
dns and ZZA ensi sva mran- Preseant in former p'ssent maseny bstensiv lire- fotenesf naua S O" Mostrlets0 Psewn i ena i sOfy Peset " $seen ofte rm te vcnnn rsn
aimin -so" am" man- sgrel"fiou luacress tereater as- Cowed ar1111 esa In tormeleimon Iln not. S4t Wastone *"in4 fdoentpmyr
-uDrms as Csuture WurAICIR smout a m Istance. mai.on"
:'groun cover mania on SNOWe and
other
0 :.*sehi. otten as 'Ivsesnt Preseet on cm mats, on rocky limestone Coastal vomlicSahme a011 n nomlrtut C ast egao Present :n4 "mey casts Wm Preonta so"t Presen
twoonosty qroctri i6 Wma P moun-. coant aft some room in north am islandSo ktaeP. towue ltt s 1151 degres sWM
tune Tstuila souther mm lImestone coest In -mcoma a
south gm 9 Mfg
la15 lante Iws 5. and Satatiere sonos to SInne WIG toaMsto" Simms teaml no salweler MO fresh- istetrP10 Sflamh A55m Sho ett5Sttt 'Skm tIef, mre Fresft ise stons Lold marshon
-stirnet amo some on"as i osflro man- rwsnm saaranaIsot res: Neo sance:t wster mersft.ise: "OM un ssafwaf& en fa felo. homate srwanw". ?ami gonsonds"se.a as
:ccur Omnin man- esterf marsisa: Man- Seoul am Pagan. ar
; Ofte "M" taste brooish on Pagan adW Mtaa 13 "f U s at fpn ce M " I AonnYL 315mwud
gm"n tarsl .5 mis scattereo Pmestrs Only an at. Psal Igoo Smugal erect pmlioc- Unifited atoms to lAdoweesOfaf one 1Wamiss OMK stioes crowa m AlfseG. NW tree aong .5 s es on mm". 155 se
a-ouna cent3 Thomas aBC so. atiesceol On Tutuila Iily Apra Hsoo t noutiter island vmaOS nn mu l es orsesaut. mu some ow to man Po Icl0ARM
Cyss £0Ot 5 Amesssm -st on Ptnela me IS Atoas"
tibsoacit Ifores 5-sneni , some 'rsssni ,vicescvein. MOSCOW1 Common. includes P'leslani some 50 of L a g" maw" or5Imwmuo5 Patientg arffa -I11 a"hg IsflarodC Ono waits n oCe On sWtSAaffmiieen
act" Pass ! osst on Posle Aeonl some erofoMICS :me soutnlern lssloan .0oons no crew -a Desilelnow bamts be-g, "soMe lby hmn behsoften an" lanem Comm mus
oe S*auna IslmI-s. 'n11, asen on 21 lyup AtOll etmned tiess ren fy tam.,u
ISiefifsiallaw tInianom:rver "esi Eatenaives in Dae. .aqounls on Rose Cocos lagoon sptislow lagoon in- L" oftet lagoon. .Sgoil wwml Sam" shallow la. Satenem lagoonatn Shouldsa s- Oer 101 O m(
0411 Ito ornner otuvord inside rest SAnO .10t. S&ans rItost soicrss o rpdlego i antdrs.se on insid wSaml Mone sgra.oon ttItnre vCfans01
I sisish si0ng sne It no IMJ Slues Sistano fime vnishi 4ayereIsmnAfol WM lune amtor agoons ams amo fsga" ole Isoofs
"It resin orir. -- nciAnn Riso a Sanscner resi Canad lamstrgely' - brnet feet veer --ingisg rrstoom- inaml f 5mV inm a w cwtona Ltseebrne sc,lnggree. Mwcerel
Wnic 1icr sees9 and siget nont: &,so ::-ec :a MOnin Coo4sao0es0.o nsunnti-en efec-ceai e by fringing rest -toal wooaln 0 oute atoW Ilatno we"tit Ise ws"oeug ,-
.5i Clraqses "iningrl partner sno ."il: Some n ta c.atch &mand s Inng- aiscome tistem. soeaa I ifiil; ms -s 1fIane emee:on"w"sbngI
baitch rest comeaiw.- :stadco 'q rests fisewneic. eAxso-m" 0so"Stis: 15"0 swnitht.a Strutures. 0
es: some damaged %&fwa darnagloo as..ute stam&M.?an ll stanos stall 155MOS eotS-
,PCt I ' es sr :nivnea Piicra Tovov0s0tnA-eir ctre v SAllae saa.CAcmisc
ti. . *-Stn-i-ci AW-t l A OI AlI'l11ai C "Il
1993 NPS Pollution Conference
HAVE YOU THOUGHT AB3OUT THIS? I!
1. WHICH OF THE FOLLOWING STATEMENTS MOST CLOSELY MATCHES YOUR
POSITION OR PHILOSOPHY? Circle the letter of your choice.
A. Future generations should not expect development
activities of today to consider their needs.
B. Substitution of resources and technology will provide the
answer to concerns about the loss of habitats and biodiversity to
future generations.
C. Humans are the only organisms with a right to access and
exploit the Earth's resources.
D. When, despite technological assistance, the capacity of
a natural system is overcome by waste and byproducts of human
society, humanity will find other resources to meet its needs.
E". The loss of most resources only have a limited negative
impact an the planet's natural systems, and in the long-term these
losses will not matter to the survival of human-built systems.
P. None of the Above.
2What resources do you see as being necessary for the future of the
U 3. Who should be responsible for efforts to sustain long-term levels
and the health of the Virgin Islands' resources?
4. If your position or philosophy was not included in number I on
this sheet, please indicate it below in one sentence.
S. Which of the following is the most important for obtaining a
development approach that provides future generations with the highest
number of options regarding development and quality of life.
* a) Financial resources
b) Technology investment
c) Economic reform
d) Directed research and monitoring
e) Institutional reform (private and public)
f) Educational reform
g) All of the above
* h) None of the above
I-21
REFERENCES
1. CARICOM. 1989. The Port of Spain Accord on the Management and
Conservation of the Caribbean Environment. Port of Spain,
Trinidad and Tobago.
2. Daly, H. 1989. Sustainable Development: Towards An Operational
Definition. Draft paper.
3. de Albuquerque, K. and J.L. McElroy. 1992. Caribbean Small-
Island Tourism Styles and Sustainable Strategies. Environmental
Management, 16(5): 619-632.
4. Economic Commission for Latin America and the Caribbean (ECLAC).
1991. Rapporteur's Report on the Round Table Meeting on Human
Resource Development Strategies. December 2-5, 1991. Havana, Cuba.
5. Gardner, L. 1992. Planning and Pollution Control. Paper
prepared as part of M.Sc. in Rural and Regional Resource Planning
at University of Aberdeen.
6. Gelabert, P.A. and N. Singh. 1992. Strategy for the Control of
Land-Based Sources of Marine Pollution in the Wider Caribbean.
Chemisti-y and Ecology, 0: 1-4.
7. IUCN/UNEP/WWF. 1991. Caring for the Earth: A Strategy for
Sustainable Living. Gland, Switzerland.
8. IUCN. (The World Conservation Union) 1993. Parks and Progress.
Ed. Valerie Barzetti. IUCN, Washington, D.C., USA
9. IUCN. 1993. First Systematic Review of National Strategies
Points to Need to .Target a Few Things and do Them Well".
Environmental Strategy: Newsletter of the IUCN Commission on
Environmental Strategy and Planning, Vol. 5.
10. Ludwig, D., R. Hilborn and C. Walters. 1993. Uncertainty,
Resource Exploitation, and Conservation: Lessons from History.
Science 260: 17 and 36.
11. Ragster, L. 1992. Contribution to the Meeting of Experts on
Land-Based Sources of Pollution: Training, Education and
Awareness. Veracruz, Mexico. July 6-10, 1992. UNEP
12. UNEP. 1989. The Action Plan for the Caribbean Environment
Programme: Evaluation of its Development and Achievements. UNEP
Regional Seas Reports and Studies No. 109. UNEP.
13. Congress, Office of Technology Assessment. 1987. Integrated
Renewable Resource Management for U.S. Insular Areas, OTA-F-325.
Washington, D.C.: U.S. Government Printing Office.
14. U.S. Man and the Biosphere Program. 1989. Puerto Rico Workshop
on Land-Based Sources of Marine Pollution in the Wider Caribbean.
August 7-9, 1989. San Juan, Puerto Rico. U.S. MAB, U.S.
Department of State, Washington, D.C. U.S.A.
15. U.S. Virgin Islands Areas of Particular Concern Management Plans.
Prepared by Island Resources Foundation for the Department of
Planning and Natural Resources, U.S.V.I. Government.
16. (The) West Indian Commission, 1992. Overview of the Report of the
west Indian Commission: Time For Action. Black Rock, Barbados.
1-22
RESPONSIBLE ECOTOURISM DEVELOPMENT
Stanley Selengut
MAHO BAY CAMPS, INC.
Ecotourism, a relatively new idea in the travel industry, is
an outgrowth of the increasing awareness that environmental
responsibility is a global concern. The ecotourist seeks
destinations that reflect this widening international ethic.
The new breed of traveler tends to be well educated,
adventurous and skeptical. An ecotourism resort that offers
only environmental window-dressing will not survive the
scrutiny of such an ecologically sensitive clientele.
My experience as builder, owner and operator of Maho Bay Camps
convinces me of this. When I first opened for business 17
years ago, the environmental movement was just beginning to
stir and the term ecotourism did not exist. My original
intent was simply to offer an inexpensive vacation that was
close to nature but provided a degree of comfort and
convenience not found in a traditional campground.
The Maho Bay site presented a unique opportunity. Its 14
acres are located within the U.S. Virgin Islands National Park
on St. John. The hillside setting overlooks one of the
Caribbean's most beautiful beaches, one of the many that
scallop the island's north coastline.
Since the land I leased was an erosion-prone hillside, site
disturbance was to be avoided. With New York architect Jim
Hadley, I designed a community of three-room "tent cottages"
set on platforms cantilevered on the hillside. The 114 units
are arranged in clusters. To further minimize site
disturbances, the clusters are connected by raised walkways
joined by stairs. Guests can reach virtually any part of Maho
without ever disturbing the ground cover. Bathhouses,
containing toilets, sinks and showers are located in various
sections of the grounds.
Construction techniques at Maho restricted the need to clear
trees and vegetation. Footings for the posts that support all
the elevated walkways and platforms were dug by hand. When
completed the tent-cottages appeared to have been built in the
trees that grew on slopes. Each tent-cottage is furnished
with beds, chairs, a table and bottled-gas cooking stove.
Occupants have unobstructed views of sea and distant islands
while the units are scarcely visible to boats cruising off the
beach.
The inconspicuous infrastructure of Maho was also designed for
low environmental impact. Electrical cables and water
1-23
pipes were attached to the undersides of the walkways,
eliminating
the need to dig trenches. Full-chain showers and low-flush
toilets reduced fresh water use in the bathhouses. A
centrally located aluminum-can compactor increased the
ef ficiency of the our recycling program. The profusion of
native trees,. plants and f lowers thrive on "gray water" that
is recycled from our treatment facility and distributedI
through an irrigation system. Birds, bats, lizards and tree
frogs f lourish under 'these conditions and keep insect
populations in check while providing entertainment f or theI
guests. Nature can be a rewarding stage, if only we keep our
props and directions from altering the original script.
Maho also has two large pavilions where guests can gather toI
see films, attend lectures by Park rangers and visiting
wildlife experts, hear live music or eat at our self-serve
restaurant which offers fresh vegetables, fish and a varietyI
of foods from a health-conscious menu. Since eating is a
universally understood cross-cultural experience, many of
Maho's dishes are prepared from local island recipes.
Educating by example is central to the Maho concept. The more
I learn about getting the most from nature with the least
environmental cost, the more I want to expand the example. I
am currently building a research/resort adjacent to the Maho
campground. It is called Harmony and is designed to take
ecotourism to its next logical level: a resort dedicated toI
the principles of sustainable development. Environmental
scientists and government agencies define this concept In
varying ways. Basically, sustainable development is theI
practice of using natural resources no faster than they can be
regenerated. In short, Do Not Kill the Goose That Lays Golden
Eggs.
Harmony will be a small community built from recycled
materials. Wood scraps, plastic bottles, crushed glass and
ground tires are now the "raw materials" for sustainable-I
development construction products. The living spaces are
designed to maximize comfort with the least amount of energy.
Harmony will run "of f the grid." All electricity will beI
generated by sun and wind, using solar panels, a windmill and
storage cells. Each unit will also contain a computer so that
guests can monitor and adjust their energy use according to
prevailing conditions.
Most of the planning for Harmony comes from discussions and
workshops with environmentalists, engineers and administrators
from the U.S. National Park Service and the U.S. Virgin
Islands Energ Office. Sandia Laboratories of Albuquerque,
N.M. is providing know how and experimental hardware, such asI
a solar powered ice machine. In a real sense, Harmony is a
proving 'ground for the latest sustainable development ideas
and technology. Practical data, including input from guests,
I-24
will be fed back to Sandia and environmental agencies. The
resort will also function as an educational facility,
attracting specialist and school children alike.
The goal of Harmony is to demonstrate that an ecotourism
U facility can balance both nature and culture -- can, in fact,
be mutually enhancing. If my experience in the f ield has
taught me anything, It is that we are not separate from but
part of our ecosystem, and with that privilege comes the
responsibility to nurture it.
12
II
URBAN SOURCES OF NONPOINT POLLUTION
(LAND USE PLANNING AND CONSTRUCTION)
General
How Erosion from Construction Projects Harms the Environment
Ralf Boulon .............................................. II-1
What You Can Do to Minimize or Prevent Erosion
Victor Giraud .................. .......................... II-6
The Benefits of Planning Development to Fit Into the Landscape
Keith Richards ..............................................
Technical
Vegetative Erosion and Sedimentation Control Practices
Dale Morton ............................................ II-12
Structural Erosion and Sedimentation Control Practices
Werner Wernicke ........................................ II-15
How to Prepare an Effective Erosion and Sedimentation
Control Plan
William F. McComb ....................................... II-25
Paper not available at time of printing.
I' Ot
EFFECTS OF EROSION ON TERRESTRIAL AND MARINE ECOSYSTEMS
Ralf H. Boulon, Jr.
Division of Fish and Wildlife, Dept.of Planning and Natural Resources,
6291 Estate Nazareth 101, St. Thomas, v.1. 00802-1104
As most of us are very aware, the Virgin Islands are a
beautiful and relatively healthy place to live. we have clean air, clear
water and examples of nearly every tropical ecosystem found in the western
However, all is not well. Our natural systems, while still
relatively healthy and productive, are gradually losing the fight against
man's activities. This paper will discuss our major natural ecosystems in
terms of their value to us and to each other, what is happening to them
due to development induced erosion in particular and what it means to us
and our quality of life here in the Virgin Islands. Development as
discussed in this paper can range from a single family residence to a
majo hoel.Erosion can be defined as the disturbance or destabilization
of soils or marine sediments which enables them to be moved' from their
point of origin by external factors such as rain, waves or currents and
which can result in a detrimental effect on natural living systems.
Disturbance or destabilization results from any activity which removes
vegetation and/or penetrates the soil or sediment surface. The steep
slopes found in the Virgin islands greatly increase the propensity for
erosion and significant soil loss.
While many aspects of development have detrimental effects on
our environment, this paper will be limited primarily to the effects of
erosion on our natural systems. The major natural systems that will be
discussed in this paper include terrestrial forests, saltponds, beaches,
mangroves, seagrass beds, coral reefs and algal plains.
Terrestrial forests - we have a variety of terrestrial forests here in the
VI. Many species of birds and animals live in them, they make oxygen for
the air we breath, they provide food for us and animals, they make our
soil, and they hold the soil where it belongs with their roots.
Through development, both residential and commercial, we have
bit by bit lost considerable amounts of our terrestrial forests which has
led to erosion and sediment washing into the ocean where it has affected
mangroves, seagrass beds and our coral reefs. This loss of topsoil has led
to changes in the types of forest capable of being supported by our land.
Thinner soils cannot support as large trees nor can it hold the moisture
necessary for the growth of many of our indigenous tree species.
Many of our guts contain rock pools that support a variety of
freshwater fish and shrimp species. The sediment produced by erosion
clouds the water and kills these animals. we have probably already lost
most of this small but important ecosystem to development.
Through proper sediment control practices and rapid
replanting,. much of this soil loss can be controlled and reduced to
p tolerable levels for our coastal and marine systems. Another related
problem is that of septic tank effluent and nutrient loading in our soils.
The creation of shallow soils through erosion reduces the capacity of the
soil to absorb the effluent. This enriches rain runoff and may cause
eutrophication of our nearshore waters which affects all of our marine
communities. Septic systems utilizing leach fields should not be allowed
under certain soil types and conditions.
Baltponds - Saltponds provide food (crabs, shrimp) for many species of
birds. They are also the front line defense in trapping soil that escapes
from the hillsides which can smother our corals, seagrasses and fish. In
fact, most of our upland watersheds end in saltponds which trap sediment
in runoff through settling action and filtration through the berm which
separates the pond from the sea. Under natural conditions, the filling of
a saltpond with upland soils takes many thousands of years, about the same
rate as which new saltponds are formed.
Historically, saltponds have been viewed as smelly areas good
for either filling in to build on top of or dredging for marinas. Either
scenario destroys wildlife habitat and causes many tons of sediment to
reach our ocean waters.
As upland sources of sediment erosion have increased we are
finding that our saltponds are filling in with this sediment at a rate far
exceeding the natural one. As this happens, the salt ponds lose much of
their retention capability and more sediment ends up reaching the sea. As
the ponds fill in with sediment, conditions become favorable for
successional colonization by wetland and terrestrial vegetation and the
size of the ponds is further diminished. Over time, our ponds may become
filled in before new ones are created and nearshore marine communities
will become smothered with sediments and die. We need to explore ways in
which natural sediment reduction systems can be enhanced, supplemented or
even replaced by man-made systems. This may become absolutely necessary if
we are going to save our nearshore marine ecosystems.
Beaches - Our shorelines contain a variety of beaches, from small pocket
coves to long open beaches. They serve as filters for rain runoff, nesting
habitat for turtles and some birds, and critical habitat for many species
of crabs and other invertebrates. Our economy also depends on beaches for
many of our tourism dollars.
Development here has certainly affected many, if not all of
our beaches in one way or another. A number of beaches have been seriously
altered through sand mining activities and erosion due to coastal
modifications such as rock groins. Increased wave erosion after
destruction of the offshore protective reefs during dredging activities
has also caused beaches to all but disappear.
Increases in terrestrial soils and organic matter from upland
erosion and runoff can lead to increased vegetative colonization of our
beaches. More soil in the sand permits more plants to grow. As more
vegetation grows on our beaches, it reduces the available habitat for
turtles and seabirds to nest. It also leads to increased root growth and
makes it harder for turtles to dig and hatchlings to survive.
Placing of sand on beaches as a beach creation project or
renourishment program can be devastating to nearby marine ecosystems if
the sand being placed on the beach is of a smaller grain size than what
was originally there. All beaches are in a state of natural equilibrium
with the wave and energy environment at that beach. Placing of finer sands
on the beach will result in the waves removing it from the beach and
depositing it on other nearshore marine ecosystems. Any project of this
nature must have grain size and composition analyses done prior to
selecting a source of sand for the project. Another mistake is when
someone wants to create a beach where there was no beach before. The
reason no beach was there before is that the energy environment will not
allow one to accrete there. Any attempt will be met with disaster, both
for the developer as well as for the nearby marine ecosystems.
Mangroves - Many of our deeper bays and larger watersheds end in mangrove
stands. These mangroves filter sediments and chemicals from rain runoff,
stabilize our shorelines, provide nesting habitat for many species of
II-2
birds, and provide nursery habitat for juvenile fish where they grow up in
the submerged roots. Mangroves are also a source of carbon based
nutrients for other nearshore ecosystems.
Mangroves are another habitat that many feel are much better
suited for cutting, filling and building on. But, in fact, they are a
habitat whose importance touches most of our lives. we estimate that we
have lost approximately 50 percent of our mangroves here in the Virgin
Islands to development activities during the last 40 years. most of this
has resulted from large scale 'destruction such as Krause Lagoon on St.
Croix or the Mangrove Lagoon on St. Thomas. Not as obvious, but also
significant, the cutting of several trees here and there for such things
as docks has eliminated much of our mangroves. And we have paid the price.
Fishermen in St. Croix tell us that fishing declined significantly after
Krause Lagoon was destroyed. Nearshore reefs in southwestern St. Croix
have been overwhelmed with sediment and have all but died. Species of
wildlife that depend on mangroves for nesting habitat where they can be
safe from predators have to deal with less safe areas to nest in, and as
a consequence, their populations decline.
The increases in upland erosion have led to changes in the
hydrodynamics and soil conditions necessary for mangrove health and
survival. As more soils are deposited over mangrove areas, soil salinity
and moisture decreases and the vegetation changes to more terrestrial
species. species of crabs that depend on the saturated soil for refuge and
the birds that depend on the crabs for food likewise suffer for the worse.
Sediments in the water clog the gills of juvenile fish and invertebrates,
causing them to die or leave. The increase in nutrients from the soils
causes algal blooms which reduces available habitat for fish. The result
is the elimination of the nursery value of the mangroves and consequently,
the reduction of fish in nearby marine ecosystems.
our mangroves are now protected by law and cutting or damaging
them is illegal. mangroves can be successfully replanted in areas where
they have been removed as long as environmental conditions necessary for
their growth have been restored. However, it is very hard, if not
impossible, to establish a viable mangrove ecosystem in an area where they
have never been.
Seaarass beds - many of our coastal bays are carpeted with seagrass beds,
the marine equivalent of a lawn. Much as a lawn will keep soil from
eroding during rain, these seagrasses stabilize the sea bottom during
periods of high waves or strong currents. They are important foraging
areas for turtles, conch and urchins, and are nursery habitat for many
juvenile fish, lobsters and other animals. Calcareous algae from seagrass
beds is the major component in beach sand here in the VI. Recovery from
damage to a seagrass bed may take decades.
The major threat to seagrass beds here in the VI has been from
dredging in the past for sand, either for construction or to fill
saltponds on which to build developments or for channel widening or
deepening. with very limited exceptions, dredging should no be longer
permitted in the VI due to the serious effects it has on all marine
ecosysytems. Replanting of seagrasses is a costly and. time intensive
project but can be done with some success.
upland erosion of soils and the introduction. of these
sedimenits into our marine waters has subtle but serious long-term
consequences for our seagrass beds. This sediment reduces water clarity
which diminishes the amount of sunlight penetrating the water. Seagrasses
require sunlight to photosynthesize and a decrease in light penetration
causes seagrasses in deeper areas to die off. This destabilizes the seabed
which leads to greater suspended sediment and a further decrease in water
clarity, thus increasing the problem. This naturally then hasa
11-3
trickle-down effect on all other marine ecosystems.
Coral reefs - we have considerable amounts of coral reef habitat here in
the VI, f ram nearshore f ringing reef s to of fshare bank and shelf edge
reefs. They are very important in protecting our shorelines f rom wave
erosion. And, like a tropical rainforest in their diversity, thousands of
species of f ish, plants and invertebrates live in coral reefs, many of
which are eaten by man. Coral reefs are also an important source of beach
sand and are vitally important to our tourist based economy.
Development has taken a serious toll on our reefs. SedimentI
and nutrient runof f from land as well as past dredging activities has
caused a serious decline in health of our reefs. in fact, several noted
marine scientists have determined that Puerto Rico has lost nearly 100
percent of its nearshore coral reefs over the past 50 or 60 years due to
sedimentation from upland erosion.
Reef s require a very narrow set of environmental conditions to
grow and maintain their health. sediment in the water smothers the coral
polyps and restricts feeding and photosynthetic activity necessary for
their survival. Without a reversal in water quality trends and increased
effort to restore the natural balance I fear that we will see a gradual
decline and eventual loss of our once productive reef areas. Establishment
of marine reserve areas with anchoring and harvest restrictions for marine
species can provide significant protection to key examples of our marine
ecosystems. These can also potentially create areas that provide a source
of recruitment of marine organisms including fish and corals to nearbyI
Alaal Dlains - A habitat that few people are even aware of is the algal
plain. These are deep water areas with high algal diversity that cover
extensive portions of our insular shelves. They may be important juvenile
habitat for some species of fish (Queen Triggerfish) and lobster.
To our knowledge, development has had little to no directI
affect on algal plains but, as the overall health of nearshore habitats
and water quality declines, the delicate balance of our algal plains can't
help but be threatened as well.
Of course there are countless other ways in which erosion is
af fecting our natural systems, many. of which we are probably unaware of .
Conclusion - One very important concept that needs to be remembered is
that all of these animals, plants and ecosystems, both terrestrial and
marine, interact with each other and are interdependent on each other for
their health and their very existence. No one ecosystem or animal should
be considered all by itself. Each one depends on the others for suchI
things as energy flow, maintenance of water quality, nutrients, shelter,
etc. But this only works if the systems are in balance. Any disruption in
the interactions between animals, plants and ecosystems can throw the
whole process out of balance.
Through effort and careful planning, we can save, protect and
enhance what we have left and possibly recover some of what we have lost.
The control of erosion and the resultant sedimentation should be one ourI
top goals. The ef fects of erosion will lead to the loss of most if not all
of our nearshore marine ecosystems. Sediment control practices must be
instituted whereever the soil is to be disturbed. These sediment control
practices must be enforced and monitored if they are going to beI
effective. Replanting of disturbed soils must be done as soon as possible
to reduce the chances of soil loss. Projects requiring major soil
disturbance should also be timed to coincide with periods of least
rainfall where possible and practical.
11-4I
IZ We must all endeavor to learn more about and try to understand
the problems that are facing our environment and ourselves. For the more
we understand, the greater will be our ability to make the right decisions
to solve those problems.
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WHAT YOU CAN DO TO MINIMIZE OR PREVENT EROSION
Victor Giraud
Department of Planning and Natural Resources, St. Thomas, U. S. Virgin Islands
A major problem faces us here in the Virgin Islands. A problem, I would dare say, is as
serious as a heart attack. That problem is soil erosion. A heart attack is normally a final
result of an ongoing disorder. Just as we change our diets when we have been told that
we have a heart condition is the same reaction we need to take when we are told that our
bad construction habits are the direct result of soil erosion. Otherwise, the final
result will be a fatal heart attack or a damaged ecosystem whenever the problems leading
up to destruction go unchecked.
Soil erosion is caused by the wind, rain, surface runoff of storm waters, and by man, who
just happens to be the greatest offender. The word erosion includes all of the processes
by which soil or rock material is loosened and removed, and then transported.
The energy of raindrops displaces soil particles from unprotected or non-vegetative areas.
Water running on the surface of the ground picks up these detached soil particles and
carries them along as it flows towards a stream system. As the volume and velocity
increase, additional particles are picked up and added to the sediment load.
Eroded soil being transported by water is termed sediment runoff. Excessive sediment
runoff in the Virgin Islands is caused primarily by increased development of previously
undeveloped lands on mostly steep slopes. Construction activity disturbs the soil by
stripping vegetation and altering natural land forms and drainage patterns. The effects
of sediment runoff are particularly noticeable in the bays and harbors adjacent to
watersheds that are being developed immediately following a heavy rainfall. The greater
the distance the water runs uncontrolled, the greater its erosive force and the greater the
damage.
Deposition occurs as the water slows down. The coarsest and heaviest particles are
transported short distances. Smaller particles stay in suspension over longer distances by
rolling or bouncing along, or stay in suspension while water velocity is fairly high.
Because of slow setting rates, fine silt particles remain in suspension for hours and
contribute to water turbidit.
Erosion in most instances is a slow but continuous removal and transportation of top soil
by the forces of nature. When assisted by man, that process is dramatically accelerated.
It is estimated that 5.4 billion tons of top soil are lost every year in the United States
alone.
In the absence of current statistical information, I would venture to say that in the
Virgin Islands, our loss to erosion is proportionately less than that of the continental
11-6
United States. However, our problem is significant enough to merit serious territory-wide
concern.
Principles Forming the Basis for an Effective Conservation Pro,,ram in Land
Development
1. Fit the development to the topography and soils as closely as possible. Don't cut
more than you have to.
2. Save trees and other natural vegetation wherever possible. Do not clear the
entire site.
3. Avoid unnecessary disturbance of the soil; confine construction activities to the
least critical areas.
4. Install permanent storm drains and roads as early as possible to direct storm
waters.
5. Protect denuded soils with mulch or grass where permanent protection is
delayed.
6. Install permanent vegetation immediately after final grades are established.
7. Use basins to trap sediment on-site.
8. Schedule the construction operations so as to only expose that area of land at a
time that can be developed in a reasonable length of time.
9. Minimize impervious areas; create lawns or gravel areas.'
The application of these principles to fit the particular type of development will result in
a practical program of environmental protection acceptable to the-industry and to the
Virgin Islands Government.
Environmental Protection Handbook, V.I. Department of Conservation and Cultural Affairs
and the Department of Public Works, 1976.
11-7
Conservation Practices
Many conservation practices have proven effective in avoiding or lessening damage from
sediment or runoff. These include:
1. Careful land. clearing and protection of desirable shade trees and other plants;
2. Proper land grading with maximum slopes;
3. Constructing retaining walls and slope stabilization structures where needed;
4. Rapidly applying permanent vegetation to critical areas following the
establishment of final grades;
5. Mulching;
6. Construction of waterways, diversions, and outlets;
7. Construct sediment basins;
8. Water storage structures (Ponds and Gray water cisterns).
Methods That are Used to Minimize Erosion 2
Depending on the type of project, slope, and soil conditioning, a combination of one or
more of these methods should be utilized in an effort to control erosion and sediment
runoff.
Silt Fences
A temporary sediment barrier consisting of filter fabric used to trap sediment while I
allowing water to flow through.
Brush Berms
Temporary sediment barriers made up of uprooted trees, brush, and grass used to trap
sediment in a similar fashion to silt fences. Brush Berms are bio-degradable.
Environmental Protection Handbook, V.I. Department of Conservation and Cultural Aff
and the Department of Public Works, 1976.
Sediment Basins (Ponds)
A sediment basin, or pond, is created by the construction of a bamrer or damn across a
drainage way, by excavating a basin, or by a combination of both to trap and store
sediment and water borne debris. The trapped water is allowed to overflow through a
filtering system - mainly gravel - onto undisturbed areas.
Mulching
Wood chips or cut grass spread evenly over disturbed ground to prevent direct impact by
raindrops.
Level Spreader
A level spreader is a flat depression constructed at grade across a slope to slow the
velocity of a concentrated runoff into a level sheet flow which is likely to cause erosion.
U Vegetative Cover
Planting of grasses, vines, shrubs, and trees on exposed areas to stabilize the soil and
reduce damage from sediment and runoff to downstream areas. Generally, vegetative
cover is used to enhance the natural beauty of the site.
Rip Rap
A permanent erosion resistant ground cover of large loose stones installed over an area
subject to erosive conditions, e.g. stream banks and drains.
Gabion Baskets
A system of wire baskets filled with rock placed strategically against cut banks to protect
I, the cut where soil conditions or water turbulence and velocity are such where soil may
erode.
U Retaining Wall
Retaining walls are walls constructed of masonry, timbers, rock, etc.. to assist in the
stabilization of cut or fill slopes and embankments.
To control or minimize erosion, one must implement a thorough maintenance and follow-
up program. A site cannot be effectively controlled without thorough, periodic checks
of erosion and sediment control practices. These practices, like the ones. mentioned
11 I-9
earlier, must be maintained just as construction equipment must be maintained and |
materials checked and inventoried. Two examples of applying this principle would be to
start a routine "end of day" check to make sure all control practices are working properly
and clean after every heavy rainfall. -
In most cases, however, a combination of limited grading, limited time exposure, and a
judicious selection of erosion control practices and sediment-trapping facilities (like the I
methods described earlier) will prove to be the most practical method of controlling
erosion and the associated production and transport of sediment.
In other words, use a common sense approach to control erosion. Look at erosion the
same way you would if you had a problem with your body; with your body being the
total ecosystem with live parts. Whenever those parts are affected, your entire body
becomes affected - sometimes to the point of disability or even death!
3Erosion and Sediment Control on Urban Areas, Oklahoma County Conservation District and
Oklahoma Conservation Commission & Soil Conservation Service.
II-10 I
BIBLIOGRAPHY
Checklist for Erosion and Sediment Control, Northern Virginia Soil and Water
Conservation District and Fairfax County, Department of Environmental Management,
1988.
Environmental Protection Handbook, The Virgin Islands Department of Conservation and
Cultural Affairs and the Department of Public Works, 1976.
Erosion and Sediment Control on Urban Areas, Oklahoma County Conservation District
and Oklahoma Conservation Commission & Soil Conservation Service.
Proerammed Demonstration for Erosion and Sediment Control Specialists. Office of
Research and Development, U.S. Environmental Protection Agency, Washington D.C.,
'1 974.
II-L
VEGETATIVE EROSION AMN SEDIBMNTATION CONTROL PRACTICES
Dale B. R. Morton
Cooperative Extension Service, University of the Virgin
Islands, St. Thomas, VI 00802-9990
Soil - this is the medium in which plants grow and obtain
most of their nutrients. The sails in the Virgin Islands are
varied in nutrient content, pH, etc. The Virgin Islands,, bein g
hilly and small in size, easily lose soil from the land to the
sea by means of erosion.
Soil erosion is the loss of soil from an area by theI
forces of wind and water. Sedimentation, on the other hand
refers to the transport and deposit of soil particles due to
erosion. Since soil is formed very slowly over many decadesI
and can be lost overnight, it is imperative for us to do all
within our means to conserve and protect this limited
resource. Therefore, some type of soil conservation practice
should be implemented by all.
However, one must be aware that erosion and soil
formation take place all the time. It is when erosion occurs
at an accelerated rate, producing large quantities of sediment
that we usually express concern. The loss of soil from
croplands, homesites, construction areas etc. is hazardous toI
marine life and costly to those who have to pay for the
removal of sediments from public places.
These costs and the environmental impact of soil erosion
can be greatly reduced by using vegetative control measures.
Once the vegetation is established the roots hold the soil in
place and the canopy of the plant protects the soil from theI
force of the rain and reduces the velocity of the wind. It is
very important to remember to avoid leaving soil exposed for
an extended period of time. When it is absolutely necessaryI
to remove vegetation, make sure that the smallest possible
area is disturbed.
There are several ways in which to use vegetation to
control soil erosion - establishment of lawns, grasslands and
pasture, contour farming, grass terraces and windbreaks. In
selecting which option is best for a particular situation,
consideration should be given to slope, soil type and
maintenance and labor.
Many Virgin Islanders use grasses to make lawns. In
Choosing the type of grass one has to take into consideration
the fertility of the soil, the availability of water, and theI
Slope of land. Once selection is made establishment can
II-12
be by seed, sprig, plugs or sod. The latter two are not very
common here. To establish the lawn one can broadcast the seed
and mulch the area. For further guidance to the selection of
grasses for lawns, you may obtain a University of the Virgin
Islands Extension Service Booklet entitled " Virgin Islands
Home Lawns".
Ground covers such as Ground Orchid or Air Plant Catopsis
morreniana, Oyster Plant Rhoeo bicolor, Wandering Jew Zebrina
pendula, Wedelia Wedelia trilobata, are sometimes used in
those areas where the slopes are too steep for the
establishment of lawns. Ground covers also have to be
selected based on the soil condition, the effect desired, and
the availability of water. For those persons living on or
near coastalareas, the Beach Morninf Glory Ipomoea pes-caprae
is an excellent choice to control erosion. All of these
ground covers have to be dense in order to provide the best
erosion and sediment control. Therefore, close planting and
fertilization are recommended to hasten the thickening and to
prevent the formation of gullies.
The practice of planting vegetation on the contour of
hills is a practice that should be encouraged. Another
vegetative practice is grass terracing. The grass Khus Khus
Vetiveria zizanioides is planted on the contour in strips. As
a result, the flow of water is reduced; the sediments become
trapped behind it. The areas in between are then cultivated
and have the advantage of better water infiltration and
percolation. These practices are not commonly implemented
here, but I think it is one to be advocated in agricultural
areas; it would be less labor intensive compared with the rock
terraces which are more commonly used in the V.I.
Another vegetative means of erosion and sedimentation
control is the practice of using windbreaks. In many
Caribbean islands along the coastal area there are plantings
of Australian Pine Casuarina equisetifolia, as wind breaks.
These reduce the force of the wind, thereby reducing erosion.
These particular pine trees also drop needles and cones which
cover the soil and protect it from further erosion. Hedges of
Tan Tan Leucaena qlauca can also be used to make windbreaks in
areas further inland.
Finally, the best and easiest means to control soil
erosion is by allowing areas to remain established in their
natural, vegetation. These plants are usually well adapted to
the area and generally thrive. They maintain a good level of
erosion control by the canopy and leaf litter protecting the
soil from the impact of the rain and reducing the velocity of
the wind.
II-13
---------------I
For further information on vegetative means of controlling
soil erosion contact any of the following local offices - USDA
soil Conservation Service, Agricultural Stabilization
Conservation Service, V.I. Department of Planning -and Natural
Resources, U.V.I Cooperative Extension Service.
11-14
STRUCTURAL SOIL EROSION AND SEDIMENT CONTROL METHODS
Werner Wernicke
Virgin Islands Water and Power Authority
A. OVERVIEW
Soil erosion is a natural process which takes place over
geologic time. It has shaped the land masses. Over millenniums
it wears down mountains and interacts in slow equilibrium with
other natural forces. It is a natural resource which
rejuvenates the fertility of the land, rivers and oceans.
Man made erosion takes place at a vastly accelerated pace
counted in years, months and days. It is a resource displaced
thereby becoming a pollutant. Natural ecosystems are unable to
respond to the rapid change imposed on it. Man made erosion
becomes highly destructive and costly both to natural and man
made environments.
Erosion strips land of is fertile soil layer, it ruts
roadways, natural and man made channels are filled with
sediment, near shore marine environments are destroys and
marine facilities are shoaled to name only a few effects.
A balance needs to exist between development and the health of
our environments as well as save guarding the value of our man
made facilities, our property andquality of-life. Most if not
all of us have witnessed the destruction brought by the floods
over the past two decades here in the islands. Much of that
damage was due to erosion and sediment damage.
B. APPROACH TO THE PROBLEM
Soil erosion and sediment deposition in this region is largely
the result of the action of rainfall and subsequent runoff.
The tools we possess to control erosion and sediment are
numerous and other presenters have covered important facets.
The basic goal is to minimize soil erosion from occurring and
to stabilize sediment which is generated. Structural methods,
the topic of this paper, is utilized in concert with other
approaches. The spectrum of erosion and sediment control is
briefly listed below: --
1. Design and plan a project with soil erosion and
sediment control as a design objective - do not view it
as a quick fix just to -get-permits.- In all cases design
a project with the minimum area of disturbance.
2. For larger projects or those situated in sensitiveI
environmental areas, phasing of site work and exposure to
seasonal weather patterns can be critical. The site's
degree of exposure to erosion-bbith in area and time needs
to be minimized.
3. Rapid stabilization of disturbed areas is necessary to
limit the exposure risk of erosion. Here structuralI
methods begin to - interact with vegetative methods in
stabilizing and protecting soil-from water erosion.
Structural methods are an integral part of the comprehensiveI
soil erosion and sediment control program. The three
overriding principles of erosion and sediment control are:
1. Minimize the soil erosion process from occurring at
the construction site an area which must be disturbed. This is
accomplished by protecting exposed soil from rainfall impactI
and controlling water run off.
2. Sediment control is a backup for erosion control
measures, it is a second line of defence to capture soil whichI
could not be successfully retained by erosion control methods.
3. The coordination of erosion and sediment control withI
water f low/storm water management both on site and leaving the
site to obtain a comprehensive and well managed program.
A number of specific structural methods are discussed below
which is followed by graphic examples'after the text and cut
sheets from manufacturers. Illustrations are taken from the
Urban Land Institute publication Residential Erosion and
Sediment Control, 1978. The cut sheets are referenced in the
text by their manufacturers name which however does not
endorse the product. Other manufactures not listed produceI
similar products.
C. STRUCTURAL METHODS
Structural methods are presented in --three categories: 1.
Erosion control, 2. Sediment control and 3. Disposal
structures. All methods are not applicable at every site and
careful planing and design is crucial for the steep terrain
encountered oh many Caribbean islands.
C.I. EROSION CONTROL
After site planning and design to minimize soil erosion, the
treatment of areas which are disturbed by earth moving
activities through erosion control methods is necessary. These
fall into two basic and interrelated methods, vegetative and
II-16I
structural.
Structural erosion control has a basic objective-
Prevent or minimize rain f all run of f from dislodging
soil particles either from direct rail drop impact and
from the scouring action of running water, over vulnerable
soil.
Shielding of exposed soil is accomplished by vegetative
measures, which is the topic of other papers presented at this
conference, and by artificial or structural means. Literature
on some commercial soil protective coverings are included at
the end of this pater. A variety of several artificial soil
* coverings are listed below:
1. Straw mulch of chopped straw will protect soil
surfaces from direct rain fall impact and keep moisture
to foster vegetative growth. It is available commercially
in rolls and reinforced with either natural or artificial
webbing or mesh to hold the straw in place. It requires
pinning to the ground. It is easily applied and is
limited to areas which are not subjected to large volumes
of concentrated water flow. Various thickness and mesh
strengths, including shredded coconut fiber, can be
applied as soil stabilization liners in small ditches.
(American Excelsior Co.,North American Green, Enka)
2. Hydro mulch is a liquid suspension sprayed from a
pressure sprayer. A mix of paper strips or straw chips,
water, grass seeds 'and a binder is projected from a
sprayer over exposed soil surfaces. It is a quick and
I. efficient method of protecting exposed soil surfaces. It
is limited to areas where protection from rain drop
impact is needed and is not applicable for swales or
drainage ways subjected to concentrated water flow. Due
to the expense of mobilizing this equipment it is limited
to larger construction jobs. It had been used for the St.
Thomas Hospital renovation several years ago. Prices
range from $0.10 to $0.40 per square foot.
3. Other proprietary fibrous applications of woven jute
mesh, stranded fiberglass applied by air pressure,
shredded wood held together with paper net and similar
material combinations are available as commercial
products. For island applications, shipping cost and
local availability are critical factors, especially for
small construction works.
The other critical consideration in erosion control is to
prevent water run of f from reaching exposed soil areas or to
* prevent the accumulation of run of f which can seriouslIy damage
NIKK
exposed soil areas. This is accomplished by a variety of water
divers ion structures which drain water towards stable areas or
existing water ways. Detailed design criteria can be found in
the V.I. Environmental Protection Handbook, manufacturer's
literature as well as text books on the subject. Structural
erosion control methods can be described as follows:
1. Diversion berms and or ditches constructed at the top
of exposed slopes to intercept and divert water flowI
towards stable receiving areas. These structures can
either be temporary for the duration of critical soil
exposure or permanent to provide long term erosion
protection. It is constructed along the contour with a
slight slope in the range of 2 to 5 percent, to prevent
erosion in the ditch. inspection after storm event is
necessary to spot and repair weak areas.
2. Temporary filter berms are stepped down a cleared
slope to shorten the vertical runoff flow distance. They
are'similar in function to diversion berms in that they
intercept runoff. The are constructed on the contour or
at a slight grade to channel runoff onto stable receiving
areas. Temporary filter -berms have found broad
application in the islands where mechanical brush
clearing is done. A mixture of a soil and brush is
scraped into berms parallel to contours at interval of 50I
to 100 feet. The soil/brush berms retain sediment as well
as filter runoff to some extent. Such temporary
structures are reasonable effective for average stormI
events. A f ield study performed an St. Croix on a
cleared 13.4 acre site protected with temporary filter
berms, with a land slope of 25 percent, showed erosion
production of 0.018 tons per acre. This sediment yield
was low compared to other study sites. If sensitive areas
lie down slope of such cleared zones then additional
protection will be needed. More permanent variations ofI
the same concept are farm terraces found in mountainous
area such as the north slopes on St. Thomas.
3. Wattling is a special manual method of stabilizing
steep slopes. Closely spaced (I to 3 foot spacing) hand
dug furrows are constructed parallel to contours. Tied
bundles of green brush, such as Tan Tan, are placed into
the furrows and staked into the ground making a
continuous row of bundles. Earth is back filled into the
brush bundles leaving them as ridges along the contour.I
the green brush cuttings will soon sprout adding to the
structural stability of the slope. This method is labor
intensive and is limited to steep slopes where machineryI
cannot operated and other erosion control methods may not
work. Locally available resources are used for this
method. Such application was successfully used to
stabilize steep slopes in the Bordeaux housing development on
St. Thomas. ( ASCE, 1980)
4. Diversion dikes are constructed across graded roads or
minor drainage ways to intercept runoff and direct it to
stable receiving areas or towards sediment control
structures. They require frequent inspection and
maintenance due to damage from Vehicular traffic. They
are intended as temporary measures until disturbed areas
are stabilized. or in case of roads, paved. A note of
caution, never attempt to interfere with or disturb the
steep natural water ways or guts found in the mountainous
areas of the islands. Only well engineered and
constructed structures will withstand the flash flooding.
5. Road Bed Paving. Dirt road ways, in land subdivision
and other developments, particularly in steep terrain,
are A major soil erosion sources. Usually roads are steep
and act as water interceptor structures from uphill
drainage areas thereby accumulating large runoff
quantities. Paving of road ways, stabilizing of ditches
and installation of drainage structures are important
structural erosion control measures. It is probably safe
to say that on islands of steep terrain, dirt road ways
without well designed drainage facilities are major
sediment contributes. A soil erosion investigation on St.
Thomas/St. Croix showed that steep dirt roads generate 10
times the quality of sediment compared to a housing
construction site. Sediment produced by a freshly graded
road generated 197 tons per acre, an old (not fresh
graded) dirt road produced 25 tons per acre while a
housing construction site produced 19 tons per acre.
(DCCA, 1986).
Variations of erosion control methods is only limited by
inventiveness. New products are coming on the market which
make erosion control efforts more effective and lower cost.
But as with any new product, the manufactures claims must be
tried in actual-field conditions. Careful evaluation of such
products that they live up to their claims is always
warranted.
C.2. SEDIMENT CONTROL
Erosion control attempts to, protect existing disturbed soil
areas from erosion. This is frequently not entirely effective
and backup sediment control, structures must be employed.
Although such structures are generally thought of as applying
to larger projects, they are also effective for small
developments even house lot construction.
The basic mechanism of sediment structures is to slow down the
U 11-19
water f low allowing sediment to settle. Larger 'particles
settle more quickly than smaller ones due to their greater
mass. Very small particles like clay will stay in suspension
due to electrostatic charges f or time spans much longer than
can be practically achieved with sediment structures. Sediment
control is also achieved by filtration through fabrics. AI
listing of basic sediment control methods is given below, and
here again is not an exhaustive list as many variation are
possible both in choice of material and design.
1. Inlet Barriers. Gravel or straw bales are placed in
front of storm drain inlets in order to trap sediments
and prevent their passage into the drainage system.
Reinforcement of gravel barriers with hallow concrete
block will improve the stability and prevent gravel from
being washed into the drains particularly if large waterI
flows can be expected. Straw bales are an option and must
be staked to the ground. Embedding of the bales a f ew
inches into the ground will prevent piping of water and
sediment below bales. Both measure are temporary, must be
inspected after storm events and be removed when soil
areas are stabilized.
2. Rock Check Dams. Usually temporary installations
placed in road side ditches or other small ditches to
slow the velocity of water flow thereby reducing itsI
scouring capacity and providing some sediment retention.
Rocks range in size from 4 to 12 inches -diameter
preferable well graded with placement intervals at 50I
feet or less. Maintenance checks and repairs are
necessary after storm events and due to vehicle damage as
well as cleaning out accumulated sediment. Check dams are
particularly useful as temporary erosion/sediment controlI
on dirt roads until paving stabilized the road bed.
3. Straw Bale Sediment Barriers. These are temporaryI
installations which retain sediment by retarding runoff
and f iltration. They can be used in combination with
gravel f ilter outlets and are useful as a perimeterI
enclosure for disturbed areas where erosion control is
not possible. Bales are firmly pinned to the ground, and
a shallow trench into which bales are placed will prevent
piping of runof f below bales. Use of untreated woodI
stakes for fastening the bales to the ground will
eliminate the need and cost of removal, both bales and
stakes will deteriorate and be merge into theI
environment. Frequent inspection is necessary to ensure
their effectiveness. Straw bales are inexpensive and
available in agricultural regions and hence not readilyI
available for areas like St. Thomas. They are usually
shipped into the islands with other materials f or larger
jobs.
TI-20I
4. Silt Fences. Preconstructed or job fabricated silt
fences have come into common use in this area. They are
compact when stored and do not degrade like straw bales.
Their function is similar to straw bales except removal
is necessary after use. Various fabrics are in use to
retain sediment and filter runoff. Most manufactures
provide installation instructions. Key elements are
sturdy supporting stakes and burial of the bottom edge in
the ground. The failure to provide the latter is
frequently observed and it allows escape of sediment
runoff below the fence, making the entire effort a futile
gesture. Silt fences can also act as water diversion
structures to channel runoff to specific areas.(Geofab,
Moore & Assoc, Amoco)
5. Sediment Traps. Traps are pits of various sized dug
into the ground at strategic locations to trap sediment
from runoff. With excavation equipment they are easy to
construct and several on one site can substitute for a
larger, more expensive sediment basin. Sediment must be
periodically removed to maintain efficiency of the
structure. When sixty percent of the original volume is
filled, the structure needs to be cleaned out. Although
their most effective use is on relatively gentle sloped
sites where rock is not present to impede excavation,
they also have a place on steeper sites, where smaller
well placed pits can effectively trap the coarser
gradation of sediments and prevent their discharge off
site. The VI Environmental Protection Handbook recommends
a minimum sediment storage volume of 0.5 inches over the
drainage area. If external runoff is diverted from the
site with diversion berms or ditches and runoff from a
site is limited to the disturbed area, then a 1/4 acre
construction site will need a trap of 17 cubic yard
minimum volume. This is a pit 3 feet deep, 10 feet wide
and 15 feet long.
6. Sediment Basins. These are fairly large and specially
designed structures primarily limited to larger
construction sites. In some cases they also function as
flood mitigation structures. Specific design criteria are
found in the V.I. Environmental Protection Handbook. Some
of the major design criteria are:
Drainage area from 20 to 200 acres
design storm frequency to 25 years
Dam height maximum of 20 feet
Emergency spillways
Minimum storage capacity of 0.5 inch of drainage
area
Larger basins have a pipe spillway which drain
basin dry whereby limited flood storage is also
achieved.
C.3. RUNOFF DISPOSAL STRUCTURES
Runoff must always be routed either through the site of from
the site. Temporary and'permanent water- ways, channels and
ditches can serve this function without erosion if adequatelyI
protected. Permanent structures are intended to outlast the
construction phase of a project or are installed -to solve a
particular soil erosion problem. The protective liner ofI
permanent structures depend on the volume and velocity of
water expected to be carried. This protection is either by
vegetation of artificial means or a combination thereof.
1. Vegetative liners are usually limited to slope ranges
from 0.25 % to 2%. Maximum water velocities range from 3
to 7 feet per second depending on the erodability of theI
soil which can be found in the Soil Survey for the Virgin
Islands. These limiting parameters make vegetative liners
suitable only for flat flood plains on the mostly steepI
islands of St. Thomas and St. John and for large gentle
sloped areas of St. Croix. Detailed design tables and
procedures are found In the V.I. Environmental Protection
Handbook and other literature sources. For steep sloped
channels, liners must be of man made materials designed
to resist the scouring velocity of fast flowing
runoff.(American Excelsior Co., North American Green,I
Enkamat, Greens treak)
2. Artificial liners are produced to supplementI
vegetative covering or entirely made of man made
materials. The latter include concrete, asphalt, metal,-
stones, gabions (rock f illed wire baskets), plastics and
similar durable material. The cost are higher than other
coverings and their application is limited to sites where
less durable liners would fail. Frequently combinations
are possible to reduce cost. A channel with it lowerI
portion of concrete and upper side slopes vegetated will
cost less than paving the entire channel. Hydraulic
evaluation is needed to determine the level to whichI
paving must be used.
Between the soft natural vegetative liners and the hard
man made ones, there is available a variety of soil
reinforcing fabrics and coverings which will tolerate
greater water depths and velocities. These are briefly
listed below and copies of manufacture catalog cuts areI
attached at the end of this paper:
11-22I
Erosion control matting is produced both from
manufactured materials such as nylon fabric fibers
or similar materials or from processed - natural sources
including paper, straw, jute, wood excelsior and other
biodegradable materials. Netting is commonly. used to hold the
U *- fibers in a blanket which is rolled over the soil," Embedding
of edges' and staking a intervals is necessary to hold the
matting in place. Proper installation is. critical to
satisfactory performance of the materials. According to
information presented by manufacturers, maximum water
velocities of 17 feet per second and water depths of 2.5 feet
can be sustained by the nylon matting (Enkamat). These
materials are light weight, although bulky, and are easily
applied. Some manufactures produce matting with embedded grass
seed. (American Excelsior Co., North American Green, Enkamat,
Greenstreak)
'Geoweblis a trade name of a cellular confinement
structure made of a plastic. Attached cells with
open top and bottom are filled with soil or gravel
to provide a erosion resistant blanket. Experience
with this product is limited but it may have
potential applications. (Presto Products Co.)
* A variety of structural erosion control and sediment control
methods have been presented. Where soil must be disturbed for
construction or other activities, erosion needs to be
minimized from taking place and that which does occur be
retained with sediment control structures. The objective is to
keep erosion rates to natural levels. Accelerated soil erosion
is detrimental and costly to natural environments and man made
facilities.
REFERENCES
1. The Urban Land Institute, ASCE,- NAHB. Res-idential Erosion
and Sediment Control - Objectives, Principles & Design
Considerations, July 1976.
2. Virgin Islands Conservation District, VI Dept. of
Conservation and Cu-ltural Affairs, VI Dept. of Public Works.
Environmental Protection Handbook, Third Ed. 1976.
3. Department of Conservation and Cultural Affairs. Sediment
Study in St. Thomas, St. Croix Areas on the United States
Virgin Islands. June 1986.
4. U S Environmental Protection Agency. Erosion and Sediment
Control, Surface Mining in the Eastern U.S., Planning and
Design. EPA Technology Transfer Seminar Publication. October
1976.
5. Virgina Soil and Water Conservation District. Comprehensive
Erosion and Sediment Control Program for Engineers, Architects
and Planners. March 1976.
Civil Engineering Magazine - ASCE. Combined Vegetative -
Structural Slope Stabilization, January 1980.
i, I
.... ." a. . "
II-24'
HOW TO PREPARE AN EFFECTIVE EROSION & SEDIMENTATION CONTROL PLAN
William F. McComb, P.E.
W. F. McComb Engineering, P.C., 129 Sub Base - Chinnery Building,
St. Thomas, USVI
The preparation of an effective erosion and sedimentation control
plan (ESCP) is not only based on engineering and scientific
principles but also on the experience and knowledge of the
designer. There can be several approaches to and designs of a good
ESCP, all of which will be acceptable and achieve the desired
results. Thus the evaluation of any ESCP must be done with an open
mind and no pre-conceived ideas.
One thing that you must remember is that an ESCP is just part of
the Earth Change Permit Application. The ESCP deals only with the
control of erosion and sediments. It does not dictate the extent
of earthmoving, site disturbance, building location, etc.. These
aspects are within the realm of the Designer. It is hoped that the
designer will take erosion and sediment runoff into consideration,
but there is no guarantees. In big projects it is likely that
someone other than the designer will do the ESCP and that person is
not apt to have much control on site design. For smaller projects
it is likely that the same person will do both and this should be
reflected in the impacts that the site plan will have on the ESCP.
The Govt. review of the Earth Change Permit Application is
important in that the reviewer can assess the impacts of the site
design on erosion and sediment generation and suggest to the
designer changes that will lessen this before it is approved.
All ESCP's want to:
a. Reduce erosion to a minimum and minimize the time period
for this to occur.
b. Control the direction and if possible the flow and
velocity of runoff.
c. Keep sediment runoff from the site to a minimum.
d. Control stormwater runoff through the site and its
effects on downstream properties.
In order to give some guidelines on how an effective ESCP can be
prepared, I will use a Subdivision that I am designing now as an
example. The parcel is 3.40 acres in size, zoned R-2 and located
in Estate Wintberg. It has been -subdivided into 11 parcels.
Figure 1.
The low point on the property is in the middle of the north
boundary. The total drainage area to this point, including the
parcel itself, is approximately 7.17 acres. Using the SCS TR-55
method to estimate the stormwater runoff in small watersheds, the
peak discharge when the site is fully developed for 50 yr. storm is
124 cfs. Figure 2. I will not review this Method as it will be
described in detail later on this afternoon. These figures are
important in order to size any drainage structures needed.
11-25
'Jo L MOA -r ROA 0
IS
11490
J10
XOL)-
Figure 1.
11-26I
Proiect : IXI. ETATE WINTRERG clUser: -
Colin Coun ST. THIOMAS State: VT Checked:
SUBDIVIST.P34,C 02'TSGN
Data: Drainaqe Area 7.17 *. Acres
Runoff Curve Number 83 *
Time of Concentration: 0.02 *: Hours
Rainfall Type II
Pond and Swamp Area NONE
Storm Number 1
--'--------------1---I----- --- ---
Frequency (Yrs) 25 : 50
24-Hr Raijnia)J (in). 9.0 1.0.4
Ia/P Ratio 0.05 0.04
Used 0.3: 0.30
Runott (in) 1 6.94 8.29
'Uniit P'eak Di scbarce ?.OA3 :2.083
(cts/acre/in)
Pond and Swamp Pactorl i..(O : 1.00I
0.0% Ponds Used
--- ------------a------------
Peak Discharqe (cts) 104 : 324
- Value(s) provided trom TR-55 system routines
.I
11 I-27
Erosion and sedimentation control are two different items. Erosion
is the effect of stormwater runoff eating away at exposed surfaces.
Sediments are. the materials which are eroded from the soil and
carried away by stormwater. Both of which are controlled in
similar and different ways.
EROSION CONTROL
One of the main means of controlling erosion is to divert runoff
from the exposed soil, particularly during construction. After
construction, the best way to control erosion is to have re-
vegetated the exposed soil. For the example given, I looked at the
possibility of diverting the runoff from the construction (cutting
of the subdivision's road). To do this a diversion ditch would
have to be constructed uphill of the road. Because of the slopes,
the extreme difficulty in digging this ditch and the construction
impacts, it was decided that this would not be done. What was done
was to slope the road into the high side of the site, figure 3
(Section A-A), and allow this to become a controlled runoff ditch,
both during construction and afterwards. This also kept storm
runoff from running down the filled sides of the road which is more
susceptible to erosion than the cut side. Section B-B shows a
situation where the road is completely on fill and a berm was used
to create the ditch. Figure 4.
Another means used to controlled erosion is that all filled slopes
and cut slopes with soil (not rock) would be stabilized with a open
web geofabric and planted with ground cover. The geofabr\ic will
reduce erosion and provide time and a stable soil surface for the
vegetation to grow. See Figures 3 & 4.
The design of the road cross slope and size of the ditch is based
on good engineering design principles for roadways and on the
amount of stormwater that has to be carried. The determination of
the carrying capacity of drainage ditches, channels, pipes, etc.,
can be done using the Manning Equation:
Q = A 1l49 R2/3 S1/2
in which:
Q = Discharge in cfs
R = Hydraulic radius (cross section area of flow
divided by wetted perimeter)
S = Slope in f t/ft
n = Manning roughness coefficient
Velocity (V) = Q
I.28I
- - - - - - - - - - - - - - - law,
3O.00 &f ROWf
?8.0 pawgwn - 00 ()p2
3 3W
RkP" Omw mc* Ai to be
&S W1.4 xx60 /1.4
FIN.Ip" to deowe
GM. amb asf-t and -i
WM il d f cre gmund ow
SECTION A -A
sol:Ham: I'm 1
*VW 1,
3(XOO* ROW
6.500 -00 ---M g60 o wen-
- 4. 14SO2.00.--%
ft6 W1.4 1.
SEC TION B -B
Soai. Hoe. - 10'
Vabt I' -
SEC77ON C ,- c
sa G ' 0
W
13
Based on this equation the carrying capacity of the ditch at
Section B-B is 12 cfs and the capacity of the ditch and roadway is
132 cfs which is greater than a 50 yr. storm. If the carrying
capacity was less than the 50 yr. storm, the ditch design and/or
the roadway cross slope would have to be changed. The comparison
of the capacity against the design storm peak discharge is
extremely conservative &s the calculated storm discharge was for
all 7.17 acres which is only true for the low point in the site.
The actual discharge at Section B-B is less as the area is smaller
than the 7.17 acres. The capacity of the ditch at Section C - C is
124 cfs, which is okay.
The rate of the velocity of the runoff will also determine what
materials will be required for the construction of the drainage
structures. For ditches/channels with velocity less than 5.0 fps,
vegetated ditches are acceptable. For higher flows, concrete or
other durable materials are required. For Sections B - B & C - C,
the velocities are 18 fps and 21 fps respectively. For the ditch
at Section C - C velocity blocks are recommended. These can
consist of concrete blocks set halfway in the concrete, at random,
about six feet apart.
SEDIMENTATION CONTROL
Some methods of sedimentation control has already been mentioned,
i. e., use of geofabric and velocity reduction. In this example
case, a sedimentation trap will be used at low point of the site,
see figure 1. A trap of 2,200 cu. ft. will be dug (50'x 15'x 3') I
and left in place until the subdivision is completed. It will have
sideslopes of 2 horz. to 1 vert. and the downhill slopes of the
spillway with be covered with nylon matting such as Enkamat. There
will be two diversions ditches, see figure 5, directing storm water
into the sedimentation trap. Upon completion of all construction,
the diversions ditches and sed. trap will be removed. By that I
time, vegetation will have re-established itself.
The diversion ditch, figure 5, combines the use of a ditch to
direct runoff to a specific area and the use of a Silt Fence,
figure 6, to control sediments in case the ditch is overtop. For
any project, the installation of silt fences is the minimum control
that should be used. In areas of large flows and/or steep slopes,
it is recommended that the silt fence be supported. In figure 6,
we used metal post and 6x6 WWF for backing of the fabric itself.
The principles used in this example can be applied to all other
projects including residential construction. The use of diversion
ditches, silt fences, planting, sedimentation traps, etc. can
easily be done. While they have a cost, it must be budgeted for as
we can not continue to pollute our waters.
II-32
ENVIROFENCE OF EQUAL.
COM4PACTED SOIM WM /aJ IlEi
OQ
RUNOFF SEDIMENTATION DITCH
rhe Envirofence Package Optional Procedures:
s designed for easy *. .The Envirofence fabric and netting can be ea
cut with a knife or scissors to accommodate P
,ield installation: need for shorter sections. The fabric and net
should be cut approximately five inches frorn
3uggested Installation Procedures: last pole. The pole should be rolled to tuck ink
Remove the system from the protective 5" overlap and to gather two wraps of fabric/n
polyethylene bag. around the pole before inserting into the grow
Unroll tepcaeby sections-pole to pole. A metal coupler is supplied with each syste
join the end poles of adjacent sections. The in
Dig a 6" x 6" trench around the perimeter of the pole of the section to be attached should b
construction area. *serted immediately adjacent to and in front
Place the sedimentation control fabric side of the end poles of the other section, so that they intE
fence in the direction of the anticipated sediment lock. The coupler is then placed over and ar
flow (net side of the system away from the flow) the two poles.
and position the poles against the back wall of
the trench. WIRE A C POLES
FILTER FA13RIC
6 xG WIRE FABRIC FI. ii
M4ETAL suPPCATNET S E ECTION 6
.POLES
U FILTER FABRIC
SECTION A
,IE v V- 1 t t TOP VIEW
PO ..AWE SOIL COUPLER
'"'" "' SECTION A
PLACEMENT OF ENVIROFENCESETOA
INTO TOE-IN TRENCH
Use a 5# sledge hammer or similar device to
drive the poles into the ground unfti the bottom
of the industrial netting is approximately 2"1 into
the trench. FROTV4.
Lay the b ottom 6 of sedimentation control fabric
, 78/ ff t£ . - COUPINGF-(AJCN
into the trench. (The same principle may be CULN FTOAJCN
employed sirriply by laying the excess fabric on EN RFNC SYTM
the ground and pilirng fill at the base.)U
FXigre 6.
·# T .. :.'' T A/
A,..,.;^. I'.>...:,.} , & .
:,. ;;...., s ;-,- · '..
:'.C:.. A' -; i.' ....
SECTION A.
PLACEMENT OF ENVIROI :ENCE i
INTO TOE-IN TRENCH - - ', =-. 7
Use a 5# sledge hammer or similar device to3.--5
drive tHe poles into the ground until the bottom j . _ .. ..:. , : ,,;, .; jj
of the industrial nettng is approximately 2' into - FOTVE
Lay the bottom 6"t of sedimentation control fabric -;:CULN FTOAJ ET
employed simply by laying the excess fabric on ENVIROFENCE SYSTEMS
the ground and piling fill at .the base.) =.
Backfill the trench with native soil and compact,
making sure the fabric toe is in p'ace.|
Figare 6. ._
TT--q/,
S REFERENCES
1. Virgin Islands Conservation District, VI Dept. of Conservation
and Cultural Aft fairs,, VI Dept of Public Works. Environmental
Protection Handbook,, Third Edition, 1976.
2. US Dept. of Agriculture, Soil Conservation Service. TR 55-
Urban Hydrology for Small Watersheds, 1986.
13
URRAN SOURCES OF NONPOINT POLLUTION
(STORMWATER RUNOFF AND POLLUTION PREVENTION)
General
Pollutants in Stormwater Runoff and Their Effects on
Water Quality
Marcia Taylor ............................................. III-1
Good Housekeeping Practices to Minimize Pollution
Timothy Cunningham ........................................ III-6
How You Can Reduce Stormwater Runoff and Pollution
Leonard Reed ....................................... III-11
Technical
How to Estimate Stormwater Runoff in Small Watersheds
Mario Morales .........................13...............
Structural Practices to Control Stormwater Runoff
Warner Irizarry .......................................... III-23
* Paper not available at time of printing.
POLLUTANTS IN STORMWATER RUNOFF AND THEIR EFFECTS ON WATER
QUALITY
Marcia G. Taylor
University of the Virgin Islands, Eastern Caribbean Center,
Virgin Islands Marine Advisory Service, RR #2, P.O. Box
10,000, Kingshill, St. Croix, VI 00850
Stormwater runoff is the water which flows over land during
and immediately following a rainstorm. The types of
pollutants that are carried with stormwater runoff is of
course dependent on the use of the land over which the rain
travels. Rainwater flowing over agricultural land will have
different pollutants than that which flows over driveways and
roads. Naturally, the types of pollutants in stormwater
runoff vary widely. Below I describe the major types of
pollutants found in stormwater runoff, their sources, and
their effect on the marine environment. I also describe how
the pollutant is regulated in the VI, the water quality
parameters which measures it, and discuss local monitoring
data relevant to the pollutant.
1) Solids or Sediment (suspended and deposited)
This pollutant is the most significant and the most damaging
type of water pollutant in the VI. The most common source is
from soil laid bare by clearing and grading. When rainwater
falls on the soil stripped of its vegetation it picks up large
amounts dirt which is carried to the sea.
Many are surprised to learn that naturally occurring "clean
soil", or non-toxic particles are pollutants. However,
especially in tropical waters, the amount of solids suspended
in the water is an important water quality characteristic. In
contrast to northern waters, the amount of suspended solids in
tropical waters is very low, making water clarity good. As a
result, tropical organisms have evolved in and require, clear
water.
Sediment in surface waters is measured in several ways, most
commonly by measuring total suspended solids (TSS), turbidity,
light penetration or secchi depth. Most states and
territories have water quality standards f or one or all of
these parameters. In the VI there is a water quality
standards for turbidity, measured in Nephelometric Turbidity
Units (NTUs), and secchi depth.
Solids affect marine life in many ways. Dirt and silt
particles that enter the marine environment eventually settle
to the bottom and can smother marine life. Corals are
especially sensitive to this type of nonpoint source
pollution. Corals have the ability to. clean particles off
their surface by secreting a mucous which sticks to the solids
and sloughs of f. However, this requires the expenditure of a
considerable amount of energy which could have been used for
growth and reproduction. Corals can survive some sediment
stress, but the constant inundation from frequent exposure to
sediment -laden water is fatal.
Particulates suspended in the water can also clog fish gills
and filter systems-*in filter-feeding animals and reduce prey
capture for sight feeding predators.'
shading is another way sediment affects marine life. Solids
suspended in the water reduce water clarity and therefore the
amount of light available to marine plants. The discharge of
sediment is usually associated with increased nutrients,I
discussed below.
The effect of introducing solids to the marine environment is
not just a short-term threat. Although solids suspended in
the water settle and the water becomes clearer, these solids
can easily remobilize when disturbed, causing additional
impact to the marine biota.
The amount of solids in coastal waters has increased
significantly over the last decade. After heavy rains many ofI
the bays have a muddy color which persist for hours or even
days. Much of our nearshore coral has been hurt from the
increased solid loads which enter our waters.
2). Nutrients and organic Xaterials
When organic material is introduced into surface waters theyI
increase the amount of nutrients, or nitrogen and phosphorus
in the water. This occurs when rain water runs over failed
septic leach systems or other areas where there are nutrients
or organic wastes such as livestock areas, and fertilized
areas. Although marine plants and animals like other living
things need nutrients, an excess can be harmful. Tropical
marine life has evolved'to live in nutrient-deficient waters
where even small increases in nutrients can be harmful.
The additional nutrients can drastically upset the water'sI
chemical balance which can result in blooms of fast-growing
species such as algae. The growth of these species can impair
growth and reproduction of the naturally occurring speciesI
such as coral, which competes with algae for space.
The addition of nutrient and organic material can also affect
marine life by decreasing the amount of oxygen available.I
During the breakdown of organic matter by microorganisms,
oxygen is used, making it less available to fish and other
organisms who need it. Dissolved oxygen levels can be reduced
to levels lethal to marine life causing massive kills of fish
and other species.
* Nutrients in the water can be measured by several water'
quality parameters such as nitrite, nitrate, ammonia, and
phosphorus. Most states have standards for at least one of
these parameters. In the VI there is a water quality standard
for phosphorous.
Excessive nutrients are a problem in many of our bays, however
there is little water quality data which shows this. Standard
methods of measuring nutrients are not always sensitive enough
to show the increases in nutrients in our waters. More
sensitive methods should be employed when analyzing tropical
waters for nutrients.
3) Heavy Metals
Heavy metals are often introduced 'into through stormwater
runoff. The heavy metals having the highest concentration in
urban runoff are copper, lead, and zinc, with cadmium beinga
distant fourth. In industrial areas and areas where sanitary
and storm water get mixed, other metals such as chromium,
mercury, nickel and selenium, arsenic can be commonly found.
Heavy metals are of concern because of their toxic affect on
many marine organisms, and those who eat them, including man.
They can affect the reproduction of fish, and accumulate in
their tissues.
Metals are not routinely monitored in the VI largely due to
the cost. The VI does not have numeric water quality
standards for heavy metals, unlike all other states and
territories. However, the US EPA has monitored the water and
sediment in the VI and identified several areas where levels
are high. Bays with marinas often have high levels of copper,
zinc and lead. Industrial areas also tend to have elevated
levels of many of these metals. In many cases the levels
found in these areas exceed National guidelines.
4) Hydrocarbons (oil and grease)
Hydrocarbons, such as oil and grease, are picked up when
stormwater runs over parking, lots, roadways, and industrial
sites. it can -also be introduced when there is illegal
dumping of waste oil. These substances are often toxic to
* many organisms in low concentrations, and other organisms
* assimilate it into their tissues, tainting it for human
- consumption. Floating oil decreases the amount of light to
benthic organisms and cuts down the amount of oxygen transfer
* across the air-water interface.
III-3
Oil and grease are measured in a laboratory in milligrams per
liter (mg/1). Although the VI, does not have a numeric water
quality standard for hydrocarbons, at many of the industrial
facilities their discharge permit requires that their
stormwater cannot exceed 15 mg/I.
Although hydrocarbons entering the sea through stormwater have
not been shown to caused significant destruction of our marine
resources, in several areas it is a problem. Oil sheens are
commonly evident around industrial areas after heavy rains.
Some are obvious by the rainbow colored sheen, although some
hydrocarbons do no leave a sheen.
5) Pathogens (Coliform bacteria and virus)
Pathogens can be introduced into the surface waters when
stormwater runs across failing septic systems or land with
animal wastes. ,Or there can be leakage from sewer lines which
can be washed to sea.
To detect the presence of bacterial contamination we test for
the indicator organism fecal coliform. To determine if the
source of the contamination is from human or animal waste, we
test for both fecal streptococcus and fecal coliform. To
protect public health, the VI has a water quality standard for
fecal coliform.
Increased levels of pathogens can pose a health risk and close
or restrict use of shellfish beds. We have seen an increase
in bacterial contamination as more and more land is being
developed. It is not uncommon for coastal waters to exceed
bacterial levels for swimming after heavy rains. This occur:-
commonly in many bay around the Territory.
6) Toxic Organics
Toxic organics such as pesticides and polychlorinated
biphenyls (PCBs) can be extremely damaging to marine
organisms. In addition, they can accumulate in tissues and
cause it to be unfit for human consumption.
The VI does not have numeric water quality standards for these
substances, nor do they routinely monitor for them. Federal
monitoring studies have not identified these pollutants as
causing significant degradation in the VI.
In general the effect of pollutants on the marine environment
depends on many things such as their toxicity, the
concentration, and where they are discharged. -Because of our
tropical environment, local plants and animals tend to be more
sensitive to some types of pollutants than plants and animals
in colder areas.
111-4
Planning is necessary in order to protect water quality from
the pollutants in stormwater runoff. The waterbody's
watershed must be carefully studied, identifying drainage
ways, flow patterns, and geologic features such as permeable
soils, and bedrock. The sources of pollutants and the
resources affected by runoff must be identified. Once this is
done, Best Management Practices (BMPs) which are appropriate
for the conditions - and concerns should be identified and
installed. Monitoring of stormwater and ambient water quality
should be implemented to check the effectiveness of the
methods.
GOOD HOUSEKEEPING PRACTICES TO MINITISE POLLUTION
Timothy J. Cunningham
Office of -the Governori Virgin Islands Energy Office
at. Croix, -U.S. Virgin Islands 00820
We cannot wait for an emergency to act on our management of
what we consider to be nwaste." Waste is defined by Webster's
dictionary as "to fail to take proper advantage of.'"
There are many inexpensive and proven methods by which we can
manage our "resources" in a responsible and advantageous
manner. The methods by which we discard our resources are
placing our land, our sea, our tourism and our health in
jeopardy. By irresponsibly discarding that which can be
reused or ,recycled, we are increasing the size of our dumps,
contributing methane (greenhouse gas) to our atmosphere, and
contaminating our groundwater.
In the Virgin Islands, we have the opportunity to use proven
methods from around the world to recover our resources and
prevent pollution. Basically, we need to re-think how we
define sustainability. We can promote jobs and awareness of
our wasteful habits hand-in-hand.
The Virgin Islands Energy Office Resource Recovery Program
provides technical support to the private sector and
government agencies on reusability, recyclability, and
financial opportunities. Working closely with local agencies,
federal agencies, the private sector, and non-profit groups
information is obtained and disseminated throughout tI
territory.
I am going to provide you with current "waste management
problems and their solutions being addressed by the Virgin
Islands Energy Office in conjunction with other agencies. In
addition to the government solutions, you will be provided
with techniques that can be applied at home and work to
minimize pollution.
One such government project involves Energy Office financial
and technical assistance to the Department of Public Works
Environmental Services Division in establishing composting
demonstration sites at nurseries and providing a limited
number of homeowners with composters throughout the territory.
In addition, VIEO has identified FEMA matching funds that will
assist DPW in acquiring equipment for a large scale composting
facility proposed for the Anguilla Dump. These projects will
demonstrate the feasibility of recycling food, yard, wood, and
paper wastes as a means of conserving water, fertilizer, and
III-6
valuable landfill space. Ani estimated 23,000 tons of paper
waste; 15,000 tons of food waste; 5,000 tons of yard waste;
3, 000 tons of wood waste; and 2,200 tons -of miscellaneous
organics is generated on St. Thomas annually. An estimated
2,000 tons of paper waste; 350 tons of food waste; 114 tons of
yard waste; So tons of wood waste; and 26 tons of
miscellaneous organics is generated an St. John annually.
At home and work the problem can be addressed by composting
our food, paper, yard, and wood wastes. In April, the Energy
Off ice hosted a series of composting workshops in both
districts. The workshops defined the methods, benefits, and
imortance of composting as an integrated waste management
strategy. Workshop packets are available free of charge. The
widespread use of compostiflg as a means of minimizing
N. pollution can be facilitated by enacting a ban on yard and
wood wastd disposal at the dumps, and by amending the VI Clean
Air Act to ban the practice of openly burning wastes as
permitted by the VI Fire Service.
The Used Oil Interagency and Ad Hoc Committee has been meeting
monthly since February to establish a permanent Territorial
used oil management plan. The improper storage and disposal
of used oil poses a threat to our soil, groundwater and sea.
By dumping oil on the ground we reduce soil productivity and
threaten groundwater. One gallon of oil can contaminate one
million gallons of water. The Energy office will be
establishing two demonstration sites on each island for a
total of six sites that will demonstrate the reusability of
used oil as a fuel extender. A portable machine will be
placed at each site that will filter used crankcase oil and
blend it at a ratio of 5 percent with diesel fuel to be burned
within the engine. in addition to using used oil as a fuel
extender, it can,' be used as boiler fuel for power generation
and as an additive in asphalt paving..
At home and work we can address the problem of crankcase oil
by changing our oil in a responsible manner. Avoid spilling
oil or mixing it with any other liquids or dirt. Pour oil
into a clean, sealable container, preferably metal. Do not
allow anything else besides crankcase oil to be mixed with the
oil. Store in a cool place away from direct sunshine and
U heat. If oil is accidentally spilled, do not wash off ground
with water, it will only compound the problem. Soak-up the
oil with either kitty litter or another material on the
market. To obtain information on how you can participate in
the Used Oil Program contact Department of Planning and
Natural Resources, Division of Environmental Protection, Laura
Hassell.
Aluminum cans are the most widely recycled item throughout the
territory. An estimated 1,000 tons and 50 tons of aluminum
III-7 .
cans are generated annually on St. Thomas and St. John
respectively.I
The Anti-Litter and Beautification Commission should be
commended on their work in promoting aluminum can recycling
and for their perseverance during difficult financial times.
At home and work, a separate bin can be placed f or the storage
of aluminum cans for redemption. By recycling one aluminumI
can, you eliminate 90 percent of the energy it would-take to
manufacture a can from virgin materials.
The incredible amount of energy expended on aluminumI
manufacturing, and the waste generated during manufacturing,
is typif ied by visiting the Virgin Islands. Alumina
Corporation. Fortunately, there are many things that can beI
done with bauxite tailings (red mud). Since May,, VIEO has
been working closely with Terra Technology to expose them to
the US Ei reau of Mines, US Small Business Administration
Pollution Control Loan Program, the Industrial Development
Commission, and the National Institute of Standards and
Technology. Terra Technology is a company that has been
researching the potential of manufacturing ceramics, floorI
tiles, roofing tiles, and cement bricks from VIALCO's waste
stream. Terra Technology was pleased to discover, through
VIEO, that bauxite tailings have been used for many years inI
ceramics, as a concrete pigment, PVC strengthening agent, road
bed surface, as f iltration for septic systems, construction of
wastewater ponds,. and in the construction of low income
housing as is being done in Jamaica.
The photocopier toner cartridge is receiving increasing
attention as. a recyclable item because of its need f orI
periodic replacement. The photocopier toner cartridge
recharging market has greatly expanded throughout the United
States and Puerto Rica. Most people consider the cartridgesI
as disposable and discard them. Toner cartridges can be
recharged at locations on all three islands. Recharging the
cartridge costs half as much as a new cartridge and .eliminates
the bulky plastic cartridges from ending up in the dump.
Our dependence on batteries poses another type of problem. An
estimated 76 tons and 4 tons of batteries are generated on St.I
Thomas and St. John respectively. If not recycled, batteries
can be a source of potential groundwater pollution.
Disposable batteries can be replaced with solar powered itemsI
that do not require a replaceable battery. If you 'must
purchase batteries, rechargeable Nickel Cadmium and a new
generation of environmentally benign batteries are readily
available. They have a much longer life than disposableI
batteries and save the user money in the long run. X-Mart
Department Stores are accepting used 6 Volt and 12 Volt
batteries to be shipped off-island for recycling.
Purchasing water in refillable three or five gallon bottles,
or better yet purchasing a water filter will alleviate plastic
waste disposal. it will save you money and eliminate the one
gallon jugs from going to the dump. If you choose to purchase
water in a one gallon jug, ref ill it at a water dispensing
machine,.or reuse the jug for used oil storage.
This leads me to the concept of waste reduction through
selective purchasing. If consumers are educated on the
benef its of purchasing products manufactured from recycled
materials versus virgin materials, consumers prefer to
purchase products made from recycled materials. Assume a
basic supply and demand principle: the more we demand,- the
more..products will be available. This will allow competition
to drive the prices down to be competitive with products made
from virgin materials. Re-refined motor oil, recycled paper
.products, factory reconditioned items, and retreaded
automobile tires are just a few examples of products that both
U the Department of Property and Procurement and the private
sectr ca besupplying to stimulate the recycled products
* market.
In keeping with the presentation title, I will mention
techniques to minimize water-borne pollution. Faucet
aerators, flow restrictors, low-flow shower heads, low-flush
or composting toilets, grey water systems, and on-site sewage
treatment are just a few examples. A publication for those
interested in minimizing pollution is entitled, "Nontoxic,
Natural, and Earthwisell by Debra Lynn Dadd. It contains the
most comprehensive listing of healthful products available and
* uses a rating system that indicates both safety and
environmental impact. It evaluates air and water filters,
biodegradable cleaners, pest controls, gardening supplies, and
more. Another publication entitled "Clean and Green" by Annie
Berthold Bond is an encyclopedic source of solutions to 485
household-problems.
The Virgin Islands is fortunate enough to have two financing
mechanisms that encourage the private sector to establish
waste management/recycling businesses. The U.S. Small
Business Administration Pollution Control Loan Program
provides financial assistance to small businesses for the
planning, design or installation of a pollution control
facility. Another opportunity to lure private companies into
the Territory is under section 936 of the United States
Internal Revenue Code. U.S. corporations receive federal tax
exemption on their profits generated in the Territory for
operating sewage, solid waste and water treatment facilities.
It is an important first step in addressing our nonpoint
source pollution problems by attending and establishing
contacts at a conference such as this. I would like to
111-9
express my sincere thanks to Joan Harrigan-Parrelly and Janice
Hodge for inviting me to be. a presenter at this conference.
On behalf of Claudette Young-Hinds,, Director of the Virgin
Islands Energy Office, I extend an invitation to everyone to
attend the Florida Solar Energy Center workshops on Oct". 22,,
23, 28 and 29, and the First Caribbean Energy Conference and
Trade Exposition to be held at Sugar Bay Plantation from Oct.
25 -28.
Ia
TTI- 01
HOW YOU CAN REDUCE STORMWATER RUNOFF AND POLLUTION
Leonard Reed
Division of Environmental Protection, Department of Planning and Natural
Resources, St. Thomas, United States Virgin Islands 00802
INTRODUCTION
Stormwater runoff occurs as a result of rain events. The runoff of stormwater
causes soil erosion and water pollution. Soil erosion and water pollution quite
often go hand in hand. Water pollution is manageable through, design and
conservation practices.
SOURCES OF RUNOFF AND POLLUTION
The sources of runoff and pollution are varied and numerous. They include the
following:
o Construction and Development Activities
land clearing
erosion and gullying due to improper changes in drainage patterns
- increase in 'runoff due to additional impermeable surfaces
-changes in peak runoff volumes [
-widespread encraochment into gut areas
- filling and development of of flood plains and wetlands
- denuding hillsides for "weed control" and cleanliness
o Agricultual Activities
nutrient loading from fertilizer use
- pesticide runoff
o Roads, Parking Lots and other impermeable surfaces
- changes in peak runoff volumes
- oil, transmission fluids, radiator coolant, brake fluids and other products
from vehicles dripping on to the ground
o Wastewater Treatment
- storm waters that are being routed into sewer systems
- storm water intrusion into sewer systems
- direct discharges of treated wastes from treatment plants into water courses
o Solid Wastes/Dumps
-lack of liners and deposition of dump material below water table
CONTROL OF RUNOFF AND POLLUTION
The control of stormwater runoff and the resulting pollution is well within man's
reach. The pollution from stormwater runoff occurs because it requires thinking and
money. The following is a list of some of the things that we can 'do tO control
stormwater and the pollution it may cause:
o Construction and Development Activities
- The practice of clearing a whole site should be discouraged, only those
portions of land that are needed for development should be allowed to be
cleared.
-Clearing should not be permitted during the rainy season. The rainy season
increases the probability of soil erosion and pollution of the waters of the
Virgin Islands.
-Currently Earth Change field inspections are performed only prior to land
clearance. A second Earth Change inspection is needed after land clearance
and prior to any construction activities.
A third inspection should be performed at the completion of construction
with a final inspection one year after occupancy to determine compliance
with the Earth Change Plan and the Earth Change Permit.
M-11 h
- Those areas that are disturbed during land clearing should be immediately
mulched and seeded.
- The proper use of silt fencing, diversions such as swales, retention and
detention basins should be mandatory in order to preserve the resources of
the Virgin Islands.
- Those established or natural drainage patterns should be maintained where
at all possible in order not to cause additional soil loss and pollution.
- When and where practicable, the maintenance of the maximum flow of
stormwater off site prior to land clearing and development should be
maintained during the life of the development.
o Roads, Parking Lots and other impermeable surfaces
- Permeable pavers, green areas for absorbtion, level spreaders should be used
to minimize the volume of water that will flow off site during and after a
storm. Retention and Detention structures should be the standard for large
impermeable sites such as parking lots.
- Regulating restrictive encroachments into our guts appears to be urgently
needed as' less natural areas are available. to detain stormwater runoff.
. Oil Water Separators should be used prior to the discharge of stormwater
from impermeable surfaces such as parking lots that can accomodate 50 or
more vehicles.
- The need to limit development of flood plains and wetlands is equally
important. Flood plains and wetlands naturally lend themselves to retention
and detention of stormwater.
o Agricultural Activities
- The use of fertilizers that will be absorbed readily by the leaves of the
plants or applied below the surface of the soil should be encouraged. We
may limit the use of fertilizers by rotating our crops.
- We may also limit the use of pesticide by crop rotation, the use of pest
resistant plants and other natural controls such as predatory insects and
repellent plants.
o Wastewater Treatment
- we need to modernize our sewer systems. Our sewer systems allow stormwater
to intrude thereby causing water pollution as they over-flow. The
intentional routing of stormwater into the sewer systems should be
discouraged. The construction of the Mangrove Logoon treatment pl.ant shoild
be accelerated. This single plant will eliminate 5 sewage treatment plants.
o Solid Wastes/Dumps
- The hardest stormwater related problem to solve is that of the solid wastes
facilities in our islands. The damage has been done and therefore use of
liners and stopping the practice of placing dump material below water table
is not practical for existing facilities. All future permit for solid waste
sites will require liners and design to control stormwater.
In conclusion, stormwater and the its resulting pollution are controlable. We must
therefore dedicate ourselves to improve our environment by all means of pollution
prevention.
III-12 I
HOW TO ESTIMATE STORMWATER RUNOFF IN SMALL WATERSHEDS
MARIO A. MORALES
United States Department of Agriculture
Soil Conservation Service
Resource Conservation & Development '
United States Virgin Islands Field Office
St. Croix, USVI 00851
Precipitation is the potential source of stormwater runoff in all
watersheds. But precipitation alone does not determine the amount of
stormwater.runoff that may occur. Other factors important to estimating
stormwater runoff include: peak discharge, size of the watershed, soils,
hydrologic conditions and topography. Each plays a very important part
in stormwater runoff and if'we are to estimate the amount of stormwater
runoff that may occur, all factors must be considered. Most of the
information that I will be presenting today is available in Chapter Two
of the USDA Soil Conservation Service Engineering Field Manual.
First, we probably need to understand why we need to know how to
estimate the amount of stormwater runoff. Estimating stormwater runoff
is required information before any type of soil and water conservation
practice or stormwater runoff control measure is implemented. The need
to determine the adequate size a structure is required, before a
detention pond, a diversion, a drop structure or any other stormwater -
runoff controlling structure is designed and constructed. Stormwater
runoff estimates provide us with a starting point for structural design.
Let us look at the, above mentioned, factors individually. Peak
discharge is the peak rate of runoff from a particular drainage area for
a given rainfall. Peak discharge is usually caused by intense rainfall.
This information is available in a synthesized form (Figures I & 2).
Rather then having to use different rainfall intensities for each
drainage area, 24-hour storm charts have been developed. There are
four different types of 24-hour storm distributions. The 24-hour storm
charts were developed by the Soil Conservation Service from U.S.
National Weather Service data for typical storms. The developed storm
charts are associated to climatic regions. This information includes
short-duration intensities with those of'longer duration. In the Virgin
Islands, our storms are classified as Type II storms. The Type II storm
is the most intense short duration rainfall classification.
The size of the watershed is important because it provides us with a
potential idea of the amount of runoff. The larger the watershed, the
larger the potential for greater amounts of stormwater runoff and higher
peak discharges. Determining the size of a watershed can be
accomplished by actual measurement. But, normally it is measured off of
a map, after the watershed has been plotted. The easiest method to
determine the area is by planimeter. What a planimeter does is measure
the square inches of the plotted watershed. That figure is then
multiplied by the coefficient for that scale of map. Other methods may
be used, but measurement by planimeter is the most common.
111-13 [
Soils are also important in estimating stormwater runoff (Figure 3).
Soil texture and inclusions are relevant to the permeability and
infiltration rates, as well as surface intake rates. Soils have been
classified into four Hydrologic Soil Groups (A, 8, C and D). Group A
consists of soils with high infiltration rates, even when wet. Please
notice that there are no soils in the Virgin Islands that are in Group
A. (Figure 4) Group B consists of soils that have moderate infiltration
rates when wet. Group C consists of soils with low infiltration rates
when wet. Group D consists of soils with very slow infiltration rates
when wet.
Hydrologic conditions on most sites affect the volume of runoff more
then any other single factor. Hydrologic conditions are a combination
of vegetative cover and conservation practice influences (Figure 5).
Any soil disturbance can significantly affect infiltration rates.
Urbanization (Figure 6) effects runoff rates because impervious surfaces
increase runoff rates, very little to no infiltration occurs.
Curve Numbers have been developed by examining rainfall runoff.
This Curve Number index is of runoff potential depending on specific
conditions.
Vegetative cover is important in estimating runoff. Vegetation and
"litter" maintain soil infiltration potential by limiting the impact of
raindrops on the soil surface. Vegetation also slows the rate at which
runoff travels across the land and allows additional time of
concentration. Vegetation also reduces peak discharge.
Established conservation practices are also important in estimating
runoff and peak discharge. Mechanical practices such as contour farming
and terracing and/or management practices such as crop rotations and no
or reduced tillage allow for additional soil infiltration potential. By
slowing the rate at which runoff travels and increasing the time of
concentration stormwater runoff maybe reduced. Cultivated land,
although easier to be dislodged, also increases the soil infiltration
potential.
Topography affects stormwater runoff and peak discharge. The slopes
of a watershed have a major impact on runoff velocity and time of
concentration, thus affecting soil infiltration rates. Additionally, we
all know that in most cases the steeper the slopes, the shallower the
soil profile, which affects soil water holding capacity.
stormwater runoff is expressed in inches. Or rather in average
depth of water that would cover the entire watershed. The volume of
runoff is computed by converting the depth over the entire watershed to
volume and is usually expressed in acre-feet. When the Curve Number and
rainfall have been determined for the watershed, runoff can then be
determined by using Figure 8.
As we have seen, many factors affect stormwater runoff. By taking
these factors into account and using the technical knowledge that is
available, we can estimate stormwater runoff in small watersheds. By
using this information and applying it at the design stage of a
development, we could minimize the effects of stormwater runoff. Proper
planning, design, and construction is much more cost effective when done
correctly the first time. The costs of correcting a poor plan, design
and/or construction can be enormous. Estimating stormwater runoff is
essential to proper planning, design, and construction.
III-14
References: USDA Sail Conservation Service - Technical
Bulletin 551 Urban Hydrology for Small
Watersheds. June 1986.
USDA Sail Conservation Service - Agriculture
Handbook Number 590, Ponds-Planning, Design,
Construction. June 1982.
USDA Soil Conservation Service - Engineering
Field Manual Chapter 2: Estimating runoff and
peak discharges. Revised.
* . A i r A, ovric 0CA
C A
III-16
4. 4
lI a a - 7 A m 9 9
tA rL Jr/ Ot AMAL.
ccwsfo tmi U.S. Virgin 7.1 so-" l5.s Z-bmw cwa nf (zinch")
III1
EIDRsonOI 8 GROUPS
PaMO RICO - V.IM 3 I3A1S 3
Revised March 1972 Figure 3
A C
Aguadilla Aceituias Ad juntas
Arenales Aguilita Aibonito Bagjura
Cataiio .Alonso Anones Caguabo
Cuyon. Amelia Cabo Rojo Camagney
Espinal Bayamon Caflabo Cartagena
Jaucas Bejucos Candelero Ciales
Meros Caribe Cayagua Cintrona
Reilly Catalina C0idral Coloso
Rio Lajas Colinas Coama Constancia
Comerio Cocega Cramer
Con sumo Corozal Cuchillas
Carnhill Cotito Descalabrado
Cortada Coto Diamond
Delicias Daguao Fe
Dique, Daguey Fortuna
Ensenada fDorothea Fraternidad
Guamana Fajardo Guanica
Guanibana 'Fredensbora Guayabota
Guayabo G3vnn Guayama
Humnacao Guanajibo GuraboI
Jacaguas Guei-ere Hesselberr,
Jagueyes Ingenio Igualdad
Juana Diaz Isaac 1acana
Lavallee Jobos Junaos
Liman. Juncal Mab.
Limones Junquitos Machuelo
Lirios Lares Maguayo
Maqrens Llancs Malaya
Maleza Los Guineas Ma unab o
Maraguez Machete Maca'
Maresua Mani )4ontegrande
Maricao Mariana Miicara
Matanzas Morado Pandura
Mayo Naranjito Parcelas
Nipe Naranjo Paso Seca
Parasol Palmaredo Perchas
Patillas Picacho ifiiones
Pellejas Quebrada Poncea
Plata Rosario Reparada
Pozo Blanco Santa Clara Rio Arriba
Rio Piedras Santa Marta Sabana
Sao Ant6n Humatas
111-18I
Hydrologic soft groups
Soils have been classified into four hydrologic soil groups
as shown in table 2-1. The four groups are defined by
SCS soil scientists as follows:
Group A soils have low runoff potential and high infiltra-
tion rates even when thoroughly wetted. They consist
chiefly of sands and gravels that are deep, well drained
to excessively drained, and have a high rate of water
transmission (greater than 0.30 inthr).
Group B soils have moderate infiltration rates when
thoroughly wetted and consist chiefly of soils that are
modetately deep to deep, moderately well drained to
well drained, and have moderately fine to moderately
coarse textures. These soils have a moderate rate of
water transmission (0.15 to 0.30 inlhr).
Group C soils have low infiltration rates when thorough-
ly wetted and consist chiefly of soils having a layer that
impedes downward movement of water and soils of
moderately fine to fine texture. These soils have a slow
rate of water transmission (0.05 to 0.15 in/hr).
Group D soils have high runoff potential. They have
very low infiltration rates when thoroughly wetted and
consist chiefly of clay soils with a high swelling poten-
tial, soils with a permanent high water table, soils with
a claypan or clay layer at or near the surface, and shal-
low soils over nearly impervious materiai. These soils
have a very low rate of water transmission (0 to 0.05
in/hr).
Figure 4
Figure 5
-4-Rinofr curve numbers for other agricultural lands,3
Curve numbers for
Cover description hydrologic 3agop
Cover type HyroogditnABc
Pasture, grassland, or rante-contnuous Poor 68 79 86I
forage for grazing.g2 Fair 49 69 79
Good 39 61 74
Meaow-oninuusgrass, protected fron 30 55 71I
grazing and generally mowed for hay.
Brush--brush-weed-rass mixture with brush Poor 48 67 4
the major element.3 Fair 35 56 70I
GINA '30 48 65
Woods-grams combination (orchard Poor S T 7-1 82
or tree farm).5 Fair 43 65 746
Good 32 58 72-
Woods.4 poor 45 66 -
Fair 36 60 73I
Good '30 55 7 0
F n steads-buildingz. lanes. driveways. -50 -14 S2
and surrounding lots.I
lAver ge rnowff conditon. and 0.2StL.
Vaw- <50% an7Z rwd Cover or fxnot bly g razedWMm u'.
50 to 750% ground MVeror=h ivgA zd wihnotb%9 muk ii.
* G ud: >75% ground ewver and lightly ur only uccwiunally gr=&J.
I44M -rO%. ground Miller.
Ftu 0 to MI% ground cover.I
Actual mine muadier is gem than 30. ww 04 m 30(4w ruzwr comuta uI=ni.
CN'sAu aba n-ere cm"Putedl rar amraif wit rmzvlsa andl Sin grze a"ua (wurer. ouw ther Lvmbinawuum of u( unditlgui., rna iorvi.
NMt thte CX'V G (ur Vqww nlpAtU*.rN.
f rFureiut iUttr. munial u.y jansd brush msv de.-troyrId by he. vr granrn or rv*tukar bumin.sw
"lets- Womjgj are stmad but naw burned, mid seeay (or t letter cuvers the ,.AI.
,.a:Wow&b asv Iwansete froim gr ng. and Uitter ami bru .A U141ateiv Mle- ler the u-a.01I
TII-20I
Figure 6 1
3 U numbeflrsi f for
Covier descriptifl hydrologic aol group-
Average percent
3 Cover type and hydrologic condition impervous area A a C 0
FUllY developed Affbn areas (Yogetbato estabfished)
3 Open space (lawns. parks. gaff courses cemeteres. etc.)':-
Poor condition (grass cowe < 50%) ... ... ... ...G 79 86 89
Fair condition (gramscovew 0% to 75%) ... ... ....49 69 79 8.4
Good condition (grass cower> 75%) ... ... ... ...39 61 74 8
3 Impervious earea.9 9 8 9
Paved parking lots, roofs, driveways aet. (excluding right-of-
Streets and roads:
3 Paved; curs and storm sewers (aexuding right-of-way) ....98 go go S s
Paved; open dithes (intcluding right-of-ov.......... 83 89 92 93
Gravel (Wncuding rdghtof-,way) ...............76 as 89 91
Dirt (hncludn righ-of-way) .................72 82 67 89
3 Western deser urbart areas:
Natural desert landscaping (pervious areas onl)'A... ... 63 77 as as
Artifical desertladscaping (Impervious weed barrer, desr
shrub with 1- to 2-inch sand or gravl mulch aNW basin bord-
U CI..........................96 96 96 96
Ubndistrictsc
Commercial and business..8. .............. as89 92 94 95
Inousrilal.........................72 SI as 91 93
Residential dsrcsby average lot size.
U 1/8 weie = or less (tow" houses) ..6............. 77 85 90 92
ll4 aim..... ....................38 61 75 83 87
113 ame........................30 57 72 SI 86
il2 acre........................25- 54 70 80O 85
Ilacre............................20 5 1 68 79 84
2 acres.........................12 46 65 77 82
Dveuvecing (rate areas
Newly graded areas (pervious areas only. no vegemtion), . . . . . . 7 86 9 1 94
Idle lands (CN's are determined'using cover types simnilar' to those
in talbte 2-2a).
* Avcage runoff condtalft.
11This average pe-vre - knpqvtous area shown was used %aode-
NS setmoisae have a CH alW 9e ad .1 stm eame ca' n.-
doted e4uamvim lo *Pen space in ged hyI Ai-A ai cormdhian.
3CtWs am"v we easivalewa i doease Pare. Cawpaosi Cm's
-cowigx - 2 OK asnium sI shoul be eamed r l'Qth
degresedc @1 evmwiwtnipervn" mm g mi g m1 9*a mpn
wa's C W PWM meme Cmd aenru numdeW Ml
* a " n"aMy"w i .1
scomoos" ewe so am Jor so de I
us e"a X"*"sodb nUda"V
degr" & 'I map nvervid" a r e a 1
Figure 7
- Cun'em on this Mshet are fot, . / r r0 "O rjr
the casel =O .2S. so that of / / ,# d' Ar jr
IP-OI2SP /4 / 9 04r *
OF of A' A0 A 0
8 HI 'i, re '0, V .
II'ct/77#t OF or OF jr - - Ar 00
00, 101, o r o r
A' AT Ar 1'r A
/ 4 , rAA i1 A41 -4 0rAr4
S A of A'0 A'- - A0P#
H In 3 PI c A0 Ar' Ar e1r Ar' At 1,
W, / OF' 2r I Ar Cd A' '4r Ar tp, .
2 -1 A' J r. r - A A A
j r A' Ar - #4 Ar r A A rA
i 1 of OF '' 4r Ao r 00,C A ?A
/0 r. c/j, A# OF rV Ar -- rp
'Jr Arr' r.Ar , Ar Op- -
/ ,, 0 rrOF o' r al W.r
Po ;dssfliiEu s...m
0 1 2 3 4 587 8911112
Rainfall (P), Inches
STRUCTURAL PRACTICES TO CONTROL STORMWATER RUNOFF
Warner A. Irizarry, PE
United State Department of Agriculture
Soil Conservation Service
Caribbean Area
P.O. Box 364868
San Juan, Puerto Rico 00936-4868
L
III-23
Root Runoff Managemet 558-1
Roof Runoff Management (No.) quency, 5-minute rainfall shall be used to design
such facilities for exclusion of roof runoff from waste I
treatment lagoons, waste storage ponds, or similar
practices. Rainfall from figures 1 and 2 or reliable
local records may be used for design.
Materials. Roof gutters and downspouts may be
made of aluminum, galvanized steel, wood, or
plastic. Aluminum gutters and downspouts shall
have a nominal thickness of at least 0.07 and 0.05 cm,
(0027 and 0020 in), respectively. Galvanized steel
gutters and downspouts shall be at least 28 gage.
Wood shall be clear and free of knots. A water-
Definition repellent preservative shall be applied to the flow
area of wood other than redwood, cedar, or cypress.
A facility for collecting, controlling, and disposing of Plastics shall contain ultraviolet stabilizers.
runoff water from roofs. Dissimilar metals shall not be in contact with each
other.
Scope Supports. Gutter supports shall have sufficient
strength to withstand anticipated water, snow, and ice
This standard establishes the minimally acceptable loads. They shall have a maximum spacing of 120 cm
requirements for design, construction, and operation (48 in) for galvanized steel and 81 crn (32 in)
of roof management facilities. Such facilities Include foraluminumrn or plastic. Wood gutters -shall be
but are not limited to erosion-resistant channels or mounted on fascia boards using furring blocks that
subsurface drains with rock-filled trenches along are a maximum of 61 cm (24 in) apart. Downspouts
building foundations below eaves, roof gutters, shall be securely fastened at the top and bottom with
downspouts, and appurtenances. intermediate supports that are a maximum of 3 m
(10 ft) apart.
Purpose Outlets. The water from roof runoff management
facilities may empty into surface drains or under-
To prevent roof runoff water from flowing across con- ground outlets, or onto the ground surface. When
centrated waste areas, barnyards, roads and alleys, downspouts empty onto the ground surface, there
and to reduce pollution and erosion, improve water shall be an elbow to direct water away from the build-
quality, prevent flooding, improve drainage, and pro- ing and splash blocks or other protection shall be
tect the environment. provided to prevent erosion.
Protection. Roof runoff management facilities and
Conditions where practice applies outlets shall be protected from damage by livestock
and equipment. Where appropriate, snow and ice
This practice applies where: (1) a roof runoff manage- guards may be installed on roofs to protect gutters
ment facility is included in an overall plan for a waste and reduce the hazard to humans and animals below.
management system; (2) roof runoff water may come Gutters may be installed below the projection of the
in contact with wastes or cause soil erosion; and (3) roof line to further reduce gutter damage from snow
barnyard flood protection or improved drainage is and ice.
needed.
Plans and specifications
Design criteria
Plans and specifications for installing roof runoff
Capacity. Design of roof runoff management facili- management facilities shall be in keeping with this
ties shall be based on the runoff from a 10-year fre- standard and shall describe the requirements for ap-
quency, 5-minute rainfall except that a 25-year fre- plying the practice to achieve its intended purpose.
SCS, June 1984
III-24
ml
I I
,Nj ±
*1
-.
I * I
.'- I
w
I-'
0 or
C
-
0 I'
U,
I.'
r -
.1
I'
A
0 -
'Ni
"5 I---
111-25 Ij
to-S. MARTLIET' OF AMMTUREFIGURE I OB-3b SOIL CONSERVATM SeRVIC
10-YEAR 6-MINUTE RAINFALL (INCHES)
a 4 44a0wa s 4w a 4
ATLANTIC O CEIA N
6i00 4745k 4S20 30 5' 45OjW4W fm
3I-'!
64 3V w 44 4w '64 4 450' 64 3 043*.
ST. CROIXA ISLANDS. ONILD
... _ .1"
W I
*4455 6410' 445' .4 40' 44 55*630
mw Numn L a - ." *'fim "
CONSRUC MAMMOLr- CAK.Mow'itr
ccwrm FM WON r.YAS 199'.. Apm 1291 10.I5-11
v 111-26
Dea.on 382-1
Dlversion (Ft) minimum the 2-year, 24-hour-duration storm. Diver-
sions that protect agricultural land and those that are
part of a pollution abatement system must have the
capacity to carry the peak runoff from a 10-year-
frequency, 24-hour-duration storm as a minimum.
Diversions designed to protect areas such as ur-
ban areas, buildings, and roads, shall have enough
capacity to. carry the peak runoff expected from a
storm frequency consistent with the hazard Involved
but not less than a 25-year-frequency, 24-hour-
duration storm with a freeboard not less than 0.3 ft.
Cross section. The channel may be parabolic, V-
shaped, or trapezoidal. The diversion shall be
designed to have stable side slopes. The ridge
Definition height shall Include an adequate settlement factor.
The ridge shall have a minimum top width of 4 ft at
A channel constructed across the slope with a sup- the design elevation. The minimum cross section
porting ridge on the lower side. shall meet the specified dimensions. The top of the
constructed ridge shall not be lower at any point
than the design elevation plus the specified overfill
Scope for settlement.
This standard applies to the Installation of all diver- Grade and velocity. Channel grades may be
sions except floodwater diversions (400) and diver- uniform or variable. Channel velocity shall not ex-
sion dams (348). ceed that considered nonerosive for the soil and
planned vegetation or lining.
Purpose Location. The location of the diversion shall be
determined by outlet conditions, topography, land
To divert excess water from one area for use or safe use, cultural operations, and soil type. A diversion in
disposal in other areas. a cultivated field must be aligned to permit use of
modem farming equipment.
Conditions where practice applies Protection against sedimentation. Diversions
should not be used below high-sediment-producing
This practice applies to sites where: areas unless land treatment practices or structural
measures, designed to prevent damaging accumula-
1. Runoff damages cropland, pastureland, farm- tions of sediment In the channels, are Installed with
steads, feedlots, or conservation practices such as or before the diversions. If movement of sediment in-
terraces or stripcropping. to the channel is a significant problem, a vegetated
2. Surface flow and shallow subsurface flow caused filter strip shall be used where soil or climate does
by seepage are damaging sloping upland. not preclude its use. Then, the design shall include
3. Runoff is in excess and available for use on near- extra capacity for sediment and be supported by
by sites. supplemental structures, cultural or tillage practices,
4. A diversion is required as part of a pollution or special maintenance measures.
abatement system.
5. A diversion is required to control erosion and Outlets. Each diversion must have a safe and stable
runoff on urban or developing areas and construction outlet with adequate capacity. The outlet may be a
or mining stes. grassed waterway, a vegetated or paved area, a
grade stabilization structure, an underground outlet,
a stable watercourse, or a combination of these
Design criteria practices. The outlet must convey runoff to a point
where outflow will not cause damage. Vegetative
Capacity. Diversions as temporary measures, with a outlets shall be installed before diversion contsruc-
life span of less than 2 years, shall carry as a tion to insure establishment of vegetative cover in
SCS, October 195
III-27
DI VERSION
I NN I -
Z:
TARAPEOIDA CROSS-SECTION
USDA-Soil Conservation Service.
DIVERSION DIKE
Definition
A temporary ridge of compacted soil immediately above cut or fill slopes
and constructed with sufficient grade to provide drainage.
Purpose
upland areas and divert it from exposed slopes to an acceptable outlet.
Conditions Where Practice Applies
The diversion dike is used for the period of construction at the top of
newly constructed slopes to prevent excessive erosion until permanent
drainage features are installed and/or slopes are stabilized.
DIVERSION DIKE
18" min. w8 min. l
.,," 7 - Stone stabilization,
/ \ min.- if required
/:1 slope or flatter
Cut or fill slope-sting
/ Existing ground
CUESS SECTION
Positive drainage. (Grade
sufficient to drain)
I AA A A A A AA AX I
IV Y Y Y Y Y Y Y Y I
I¥ V V¥. V v
Cut or fill slope
11I-29
USDA-Soil Conservation Service
INTEEPTOR DIKE
Definition
A temporary ridge of compacted soil, located across disturbed areas or
rights-of-way.
Purpose
The purpose of an interceptor dike is to shorten the length of exposed
slopes, thereby reducing the potential for erosion, by intercepting storm
runoff and diverting it to a stabilized outlet or sediment trapping device.
Conditions Where Practice Applies
Interceptor dikes are constructed across disturbed rights-of-way such as for
pipe lines and streets or disturbed areas such as graded parking lots or land-
fills. The dikes shall remain in place until the disturbed areas are
permanently stabilized.
INTERCEPTOR DIKE*
(not to scale)
2'
l8\ * 1B- mi n. | Flow
z 2 \Existing orI
L / [ "Graded Rght-of-Way
2:1 slope s or flatter t-of-way
CROSS SECTION
Y/.2' min.
_Right_ _ Aft - -- hFlow
of
Way Flow
lope Toe
Property Line or kOutlet onto stabilized area or into
Limits if Right-of-way sediment trapping device, as required.
PLAN VIEW
III-30
usA-soil conservation service.
'S=MNAIM MM SPCWMICATTONS
I., FOR
PE2RINETR DIKE
Definition
U A temporarY ridge 'Of compacted. soil located along the perimeter of the site
*or disturbed areas. e
_ ups
The purpose of a perimeter dike is to prevent of fsite storm runoff from
ante-ring the disturbed area and to prevent sediment laden storm runoff from
leaving the construction site or disturbed area.
conditions lWhere Practice Applies
The perimeter dike is used for the period of construction at the perimeter of
the disturbed area to transport-sediment laden water to a sediment trapping
device such as a sediment trap or sediment basin. This dike shall remain in
place until the disturbed area i s permanently stabilizedl. The storm runoff
prevented from entering the disturbed area by the perimeter dike shall be
adequately handled to prevent damage due. to flooding or erosion to, adjacent
property-.
PERIMETER DIKE
(not to scale)
2'
3 2:1 slope or flatter
CROSS SECTION
Positive drainage. (Sufficient
Iupslope grade to dri.
IA A Al Al
* IVI
INTECEPTOR SWALE
Definition
A temporary excavated drainageway located across disturbed areas or rights-
of-way.
Purpose
The purpose of an interceptor swale is to shorten the length of exposed
slopes, thereby reducing the potential for erosion, by intercepting storm
runoff and diverting it to a stabilized outlet or sediment trapping device.
Conditions Where Practice Applies
Interceptor swales are constructed across disturbed rights-of-way such as
for pipe lines and streets or disturbed-areas such as graded parking lots or
land fills. The swale shall remain in place until the disturbed areas are
permanently stabilized.
INTERCEPTOR SWALE
(not to scale)
2:1 or flatter
-- - - H- Graded Right-
' min. L of-Way
7|ain. Level
Imin.
CROSS-SECTION /
_____ . ./ 7__in.
Right - . Flow
--of -- _ --£
__ Way
Outlet onto stabilized area
III-32
PERIMETER SWALE
Definition
A temporary excavated drainageway located along the perimeter of the site or
-disturbed areas.
Purpose
The purpose of a perimeter swale is to prevent offsite storm runoff from
entering the disturbed area and to prevent sediment laden storm runoff from
leaving the construction site or disturbed area.
Conditions Where Practice Applies
The perimeter swale is used for the period of construction at the perimeter
of the disturbed area to transport sediment laden water to a sediment trapping
device such as a sediment trap or sediment basin. This swale shall remain in
place until the disturbed area is permaaently stabilized. The perimeter
swale also is used to prevent storm runoff-from entering the disturbed area.
This runoff shall be adequately handled to prevent damage due to flooding
or erosion to adjacent property.
PERIMETER SWALE*
(not to scale)
2:1 or flatter _
_-, Existing ground
|V 7' min.
level
Flow CROSSSECTION Flow
AS orsteeper, dependent on topography '
V Y * Vt T. Y 1 Y V Y f -Y EYI
IcI A I L A A I L i A A
Outlet as required. PLAN VIEW
See item 6, below. Construction Specifications
m! III-33
IlI
3 111 I-33L
Grassed Watergy 412-1
Grassed Waterway (Acre) chodg, straw or hay bale dikes. or other diversion
methods are wanranted at this crtical period. Sup
plemntm Iingaton may also be warranted. The
egetaton should be well establshed before large
flows are pemnited In the channel.
DeOign criteria
Capaty. The minimum capacity shall be that re-
quired to convey the peak runoff expected from a
storm of 10-year frequency, 24-hour duration. When
slope is less than 1 percent, out-of-bank flow may be
permitted if such flow will not cause excessive ero-
sion. The minimum in such cases shall be the
Definition capacity required to remove the water before crops
are damaged.
A natural or constructed channel that is shaped or
graded to required dimensions and established In Velocity. Design velocities shall not exceed those
suitable vegetation for the stable conveyance of obtained by using the procedures, "n" values, and
runoff. recommendations in the Engineering Field Manual or
SCS-TP-61, Handbook of Channel Design for Soil
and Water Conservation.
Scope
Width. The bottom width of trapezoidal waterways
This standard applies to natural or constructed chan- shall not exceed 100 ft unless multiple or divided
nets that are to be established to vegetation and waterways or other means are provided to control
used for water disposal. Grassed waterways with meandering of low flows.
stone centers are also included.
Side slopes. Side slopes shall not be steeper than a
ratio of two horizontal to one vertical. They should
Purpose be designed to accommodate the land user's
equipment.
To convey runoff from terraces, diversions, or other
water concentrations without causing erosion or Depth. The minimum depth of a waterway that
flooding and to improve water quality. receives water from terraces, diversions, or other
tributary channels shall be that required to keep the
design water surface elevation at, or below, the
Conditions where practice applies design water surface elevation in the terrace, diver-
sion, or other tributary channel at their junction when
All sites where added capacity, vegetative protection, both are flowing at design depth.
or both are required to control erosion resulting from
concentrated runoff and where such control can be Drainage. Subsurface drains (606), underground
achieved by using this practice alone or combined outlets (620), stone center waterways, or other
with other conservation practices. This practice is not suitable measures shall be provided for in the design
applicable where its construction would destroy im- for sites having prolonged flows, a high water table,
portant woody wildlife cover and the present water- or seepage problems. Water-tolerant vegetation such
course is not seriously eroding. as reed canarygrass may be an alternative on some
wet sites.
Planning considerations Outlets. All grassed waterways shall have a stable
outlet with adequate capacity to prevent pending or
The most critical time in successfully installing flooding damages. The outlet can be another
grassed waterways is when vegetation is being vegetated channel, an earth ditch, a grade stabiliza-
established. Special protection such as mulch an- tion structure, or other suitable outlets.
SCS, October 1985
III-34
- - - m - - ----------- - -
GRASSED WATERWAY
- -'S.--.-
*-
-
I - I
___ z- J'
Z L I
b
TRAPEZOIDAL CROSS-SECTION
rn-I
'-4
I-0
'-ft
VI-'
-
.* 4A-
-'S.---
-I i. -
L
D/4t T/2 I
T
PARABOLIC CROSS-SECTION
I -, . <4
USDA-Soil Conservation Service
STAMDARD AND SPECIFICATICS
FOR
LEVEL SPREADER
Definition
An outlet constructed at zero percent grade across the slope whereby concen-
trated runoff may be discharged at non-erosive velocities onto undisturbed
areas stabilized by existing vegetation.
Purpose
The purpose of the level spreader is to convert a concentrated flow of sedi-
ment-free runoff (e.g. diversion outlets) into sheet flow and to outlet it
onto areas stabilized by existing vegetation without causing erosion.
Conditions Where Practice Applies
The level spreader is used only in those situations where the spreader can be
*constructed on undisturbed soil, where the area directly below the level lip
is stabilized by existing vegetation, where the drainage area above the
spreader is stabilized by existing vegetation, and where the water will not
be reconcentrated immediately below the point of discharge.
LEVEL SPREADER
Last 20' of (not to scale) _ -
diversion not elo
exceed 15 grade , ..- , " ' - -
Diversion V4 {g _t r Level Spreader
I/ ---
Diversion : --
. ? - " -' * ---- .:-. ' -
--* ;: - -'-, ' v- Stabilized slope
- _ ,fI.? 4 11 Channel grade 0O
-^ Aiwtl i- ; tj# 6z g ^u t*_*ir
_- U... '- - a - -- .. -
-- I--'-
Undisturbed outlet - - -,, - . -
Both strips of protective
material over erosion stop
/ 4" in.
6' min.
First strip of - Second strip |_
protective mate:ra $ l / For staple requirements see
/ - - Standard & Specifications
- 76' min / for Protective Materials
of spreader
Fiberglass matting erosion stop
CROSS-SECTION
STONE OUTLET STRUCTUR E
Definition
A. temporary crushed stone dike installed in conjunction with and as a part
of a diversion dike, interceptor dike, or perimeter dike.
Purpose :
The purpose of the stone outlet structure is to provide a protected outlet
for a diversion dike, interceptor dike, or perimeter dike, to provide for
diffusion of concentrated flow, and to allow the area behind the dike to
dewater.
Conditions Where Practice Applies
Stone outlet structures apply to any point of discharge where there is need
to dispose of runoff at a protected outlet or to diffuse concentrated flow
for the duration of the period of construction. When the entire drainage
area to the structure is not stabilized, a sediment trap must be. provided in
conjunction with the stone outlet structure (See Standard and Specifications
for Sediment Trap).
STONE OUTLET STRUCTURE*
(not to scale)
Flow min.t',.min. [.
Earth dike .:. :. .
Flow
;>(as shown on pI ). m in. I
f121 nin. ....., . 2.'m
Stone emeded'PRF.Eround line
nun,4 . .O- ....',I- ,
· *ttlII t I3,
L i/
Level II3 [rs
GRKDE 5TAqXJLIZATIO0N STIWCTURE .
(PAVED CHUTE OR FZAME)
A temporary channel lined with bituminous concrete, portland cement concrete,I
or comparable non-erodible smaterial. placed to extend from. the top of a slope
to the bottom of a slope.
Purpose
The purpose of the paved chute or flume is 'to convey surface runoff safelyI
down slopes without causing erosion.
Conditions Where Practice Applies
A paved chute or flume is to be used where concentrated flow of surface runoff
must be conveyed down a slope in order to prevent erosion. The max imum allow-
able drainage area shall be .36 acres.
.' Top of erth dikceA PAVED CHUJTE.O(R .D*Sze rou
staee3plaer th and:S-IL S, 6
for dra inaoie un-der outlet -is shown
for full width of stnxxture
Riprap 1s; 91 lay er of
6M min. rock or rubbleI
per ft
A A A A, I 2 1
7
SECTIONV 8-6.
III-38
GRADE STA BILIZATIONI STRUCTURE
(PIPE SLOPE DRAIN)
Definition
A flexible tubing and/or rigid pipe with prefabricated entrance section tem-
porarily placed to extend from the top of a slope to the bottom of a slope.
purpose
The purpose of the pipe slope drain is to convey surface runoff safely down
slopes without causing erosion.
Conditions Where Practice Applies
Pipe slope drains are. to be used where concentrated flow of surface runoff
must be conveyed down a slope in order, to prevent erosion. The maxi'u
allowable drainage area shall be 5 acres.
PIPE SLOPE DRAIN (RIGIO)*
Discharge it
stailied atercourse,
sediment t rappirng device, Ctvyue
or onto stabilized area. toshwine
H :: . 7:2 ' - Earth Dike
L ength as necessarx1 to go Standard Flared
thru di"kftr ectio
o imtr Stnepacd sahpwn
less than 1% slope Depth of apron shall equal the
pipe diameter and riprap shall
be a minimum of 122 in thickt-
ness.
?AorX: Size designation is: PS-PiPs WiM.
(ex., pSD,-l2-pipe Slope Drain wid h 12- diainete ;dffe) RIPP.RP APMF. PLAYE
TTT 'AO
GRADE STRELIMMM19N STRUCTJRE
(PIPE SLOPE DRAIN)U
Definition
A flexible tubing and/or rigid pipe with prefabricated entrance sectiLon teia-
POraTJ-lY placed to extend from the top of a slope to the bottom of a slope.
Purpose
The Purpose of the pipe slope drain is to convey Surface runoff safely downI
sloPes without causing erosion.
Conditions Where Practice AppliesI
Pipe slope drains are to be used where concentrated flow Of surface runoff
must be conveyed clown a sl-ope in Order to Prevent erosion.* The maximum
allowable drainage area shall be 5 acres.
PIPE SLOPE DRAIN (FLEXIBLE)*
Discharge into a (not to scale)
stabilized watercourse,
sediment trapping devfe NOTE: Size design ation is.
- . S-PIPe Diam. (ex., PSD-18m
or onto a stabilized"=a Pipe Slope Drain with 18'
*1 daee pipe)
*' * **.** S*.* *Ea th..* k
Leghas Asmexyaz
to go thru dike odfee
FTEntrance sectionU
2 2-pipeRirvsalcnitf6
aRFLEdaeterstneplce a
pipe riprap shall conis of mnmu
of 12" in thickness.
Construction Specifications ArRA APO PLAN
TTT-40
U SEDIMENT TRAP
Definition
A small temporary basin formed by excavation and/or an embankment to inter-
cept sediment laden runoff and to tray and retain the sediment.
The purpose of a sediment trap is to intercept sediment laden runoff and
trap the sediment in order to protect drainagewaYst properties, and rights-
of-way below the sediment trap from sedimentation.
conditions Where Practice Applies
A sedimnent trap is usually installed in a drainagevay, at a storm drainr
Wnet , or at other points of discharge from a disturbed area.
EARTH4 OUTLET SEDIMENT TRWP
z efvate It ulssary, for Aterage
S Flow '
) , . 4' Torp width. ,.
Dike If required to divert water to trap
_ or flaster
* V 91- - widh (ft.) -
r Drainage Area (Ac.)
EXCAVATED EARTH OUTLET SEDIMENT ENRANIKNENT EARTH OUTLET SEDIMENT
TRAP TRAP
111 I-41
PIPE OUTL.ET SEDIMENT TRAP- -
Earth Embankment . ..* .-
cutlet Protecton
All slopes 2:1
o r flatter 1-0At]
- 5' max. PerforaItedI
ENBANIGEEN? SECTIGN MU RISER I
ST(WE OUJTLFT SEDIMENT TRAP*
Excavate, if necessary , tar - N.
storage -
Earth Ema nhwnnt. - Flow f .
cutaw ay to. show srw. -
bale core I
Len(Ith (ft.) 4
/ *..¶. J6 x Drainage Area (Ac.)i
"(_7_
.... .
ear e.m*an.-e.
STORM INLET SEDIMENT TRAP*
BlokC inlet with plywOod
and sandbags, as necessary,.
to Prevent water from entering.
Plo" -,- .-iar
'-.T. - ' t .V
pemove bc z
blod*sf Ot
rrap may be placed behind Or
As Nequized at and of Inlet-
ks re iedj7 2.1 or flatter 2:1 or flatter
,·=- 7 ;/A
Adn
Uc -sCr(lSECf 1011 A-A
CURB DRAIN
YARD DRAIN mOTE: fber curb IS In Place, Provide
a I ft. wide qpIng In th. curbe
or a a asa"g dm to 1o0r
vat.r over the curb to the trap-
III-43
111I-43 Li
SEDIMENT BASIN
Definition
A temporary barrier or dam constructed across a waterway or at other suitable
locations to intercept sediment-laden runoff and to trap and retain the sedi-
ment.
Purpose
The purpose of a Sediment Basin is to intercept sediment-laden runoff and
reduce the amount of sediment leaving the disturbed area in order to protect
drainage ways, properties, and rights-of-way below the sediment basin from
sedimentation.
Conditions Where Practice Applies
A sediment basin applies where physical site conditions or land ownership
restrictions preclude the installation of erosion control measures to adequa-
tely control runoff, erosion, and sedimentation. It may be used below con-
struction operations which expose critical areas to soil erosion. It remains
in effect until the disturbed area is protected against erosion by permanent
stabilization.
PIPE SPILLWAY DESIGN
Anti-vortex Device (see page A-19.17 for detail)
ater surface (design) Emergency Spillway Crest
Anti-seep collars Outlet
r r V Pipe conduit or barre H
DJV
1-44L
IV
ON-SITE SEWAGE DISPOSAL SYSTEMS (OSDS)
General
Operation and Maintenance of Standard Septic Systems
Julie Wright ....................................... IV-1
Alternatives to Standard Septic Systems
Tom Linnio ................................................. IV-5
Technical
Standard Septic System Siting and Design For the
Virgin Islands
Barry W. Kimball .V-11
Barry W. Kimball ........................................ IV-1
Alternative Septic System Design
Douglas White ..............................................*
PpenoaaialattMofPIntIng1
I·l
*. * Paper not available attime of printing.
: X!00?: fI -0..:;0 fC !.
SEPTIC SYSTEM OPERATION AND MAINTENANCE
Julie A. Wright
Cooperative Extension Service, University of the Virgin Islands,
St. Thomas, VI 00802
Introduction
A large portion of the habitable land in the Virgin Islands is zoned for residential use.
Many of the buildings on this land are not connected to a public sewage treatment
system; instead they have individual septic systems. Standard (State-side type) septic
systems currently in use in the Virgin Islands have problems properly treating wastewater
due to both environmental and demographic constraints. This is because our soils are
either too thin (there is not enough soil overlying the bedrock or alluvial aquifers that can
filter pollutants) or too impermeable (the soils do not allow wastewater to filter through
rapidly enough, causing waste to seep to the soil surface). Similarly, development
density contributes to septic system failure by siting systems too close to one another, so
close that there is not enough soil per septic system to properly treat the wastewater.
Public Health officials on St. Thomas and
St. Croix have reported that over 400
septic systems fail per year on each .
island. Failing septic systems can IO' from 5' to property line
[ -foundation-... --
contaminate both ground and surface I o.: .
waters with harmful bacteria and viruses H o.us Septic L4 -
I I I I tank l
as well as nitrate (a nutrient). In areas L.....· -
where septic systems are located in 04-I100 to private-. -_
fractured bedrock, bacteria and viruses well I t
can be transported very rapidly and
contaminate wells, cisterns, and coastal
waters. These organisms can cause Figure 1. Example of septic system layout.
human health problems--illnesses such as
gastrointestinal infections, typhoid fever, and infectious hepatitis have been linked to
sewage contamination of drinking waters. Therefore it is very important to make sure
cisterns and well casings are properly sealed and separated from the septic system area.
Figure 1 presents an example layout of a septic system.
Other chemicals commonly used by homeowners such as pesticides, paints, varnishes,
thinners, and caustic cleaners can also contaminate waters if they seep out of septic
systems. Chemical contamination is especially dangerous since some chemicals. even
in small amounts, are almost impossible to remove from groundwater.
Failing septic systems can also reduce the value of your property and be expensive to
repair. Be aware of the following warning signs that signal septic system failure:
IV-1
*Sewage surfacing over the drainfield (especially after storms);*I
*Sewage back-ups in your home;
*Lush, green growth over your seepage pit or drain field;
Slow-draining toilets or drains; and/orI
There are some signs that can tell you if contaminants are reaching surface or groundI
waters. Look for the following symptoms of sewage contamination:
*Excessive weed or algae growth in the water along shorelines;I
*An increase in infections (like staph infections) or illnesses associated with
swimming in the area;
*An increase in infections (such as gastroenteritis) or illnesses associated with
drinking contaminated water; or
*Unpleasant odors, soggy soil in the area of the septic system, or liquid waste flow
over the land surface.
What You Can Do
There are many things that homeowners can do to prevent septic system failure and to
ensure that their septic systems work as well as they possibly can. In order to properly
care for your septic system, you first need to know where it is located. Unfortunately,
manholes and/or inspection ports are often buried in the yard somewhere. To locate your
tank, find where, and in what direction, the sewer pipe goes out through the wall in yourI
home and check for manholes just under the surface of the yard in that direction.
Septic system operation and maintenance practices fall under three general categories:I
septic (or holding) tank monitoring and maintenance; absorption field (seepage pit or
drain field) monitoring and maintenance; and system input.
Septic Tanks
Septic systems should be inspected at least once every three years to determine if yourI
septic tank needs to be pumped. (Figure 2 shows a typical septic tank.) While your tank
is being inspected, ask the contractor to examine the inlet and outlet baffles (or tees).
If either is broken, have repairs done immediately. The inlet should also be checked to
see if wastewater is continuously flowing into the tank from-previously undetected
plumbing leaks.
Your septic tank should be designed to have enough space for solids to accumulate for
at least three years. However, how often you need to pump your septic tank depends oil:
* The size or capacity of the tank;
* Wastewater flow (which depends on the amount of water used); andI
* The volume of solids in the wastewater (for example, a garbage disposal can increase
the amount of solids in wastewater by up to 50%).
IV-2
The contractor hired to inspect your
septic takshould use the large
manhole when pumping the tank. If Inspection ports
the inspection port is used to pumpMahl
septage the b affles in the septic tank
could be damaged. The use of
biological or chemical septic additives Su
will not eliminate the need for
pumping your septic tank. Some InletUte
chemical additives can actually harm
your septic system by killing the
bacteria that break down (digest) the
solids in the septic tank.
It is very important to ensure that Figur 2. Cross section of a septic (or holding) tank.
there are no cracks or leaks in your
septic tank. Septic tank water-tightness is critical to efficient reduction of solids. Leaky
tanks allow water to seep in, causing less efficient solids reduction and, therefore, the
need for more frequent pumping. Leaking septic tanks also have less storage volume for
surface scum (oils, grease and other materials that float on top of the wastewater in the
septic tank) and sludge (solids that settle to the bottom of the septic tank). This disrupts
the normal solids sedimentation and separation of fats, oils and greases from the
wastewater. It also causes loss of bacteria that biologically break down and reduce the
volume of solids in the septic tank.
Septic tanks are usually constructed of pre-cast concrete. However, fiberglass and
polyethylene tanks are also available. Fiberglass and polyethylene resist erosion and
decay and are lighter and easier to transport than pre-cast concrete, but are also more
expensive. Whatever material is used for your septic tank, you should make sure tahit
your tank is properly sealed. A well-designed tank should last at least 50 years.
Absorption Fields
The absorption field of your septic system (the area where the seepage pit or distribution
lines are buried) should be routinely checked for sogginess or flooding. These conditions
usually indicate:
* Improper drainage;
* A clogged system, and/or
* * Excess water use.
The following is a list of some fairly common-sense do's and don'ts that will help your
absorption field have a longer life span.
*Don't drive over your absorption field with cars, trucks, or other heavy
equipment.
IVI-3
* Don't plant trees or shrubs in your absorption field-plant only grasses or other
shallow-rooted plants (such as banana trees).
* Don't cover your absorption field with pavement, concrete or any other
impervious surface.
· Do divert stormwater runoff away from your absorption field so that it will not
flood.
System Input
What you put into your septic system will directly affect the system's health and
durability. Many common household chemicals and items can harm your septic system:
* Do not dump toxic or hazardous chemicals in the toilet or down the drain.
Even small amounts of paints, varnishes, thinners, waste oil,..photo chemicals,
and pesticides can kill the beneficial bacteria in your septic system that treat
wastewater through biological processes. Caustic cleaners and drain openers (like
Draino) can also harm your septic system. Instead, use boiling water or vinegar
and baking soda to keep your drains unclogged, and use biodegradable cleaners.
(A mixture of 'A cup white vinegar, 'h cup ammonia, 'A cup baking soda, and
%'/ gallon water is a cheap, effective and non-harmful cleaner.)
* Do not throw cat litter, plastics, cigarette butts, sanitary napkins, disposable
diapers, paper towels, or tissue in the toilet or down the drain. These
products do not readily degrade and can block septic tanks and clog pipes.
· Do not dump grease, fats or oils down your kitchen drain. These products
will also clog pipes and block your septic system.
Another way to increase the life-span of your septic system is to conserve water. Repair
dripping faucets and leaking toilets; avoid long showers; do not run water in sinks and
showers while soaping up, shaving or brushing teeth; use water-saving devices like
aerators in faucets and showerheads; install water-saving devices (like a brick or
weighted plastic bottle) in toilet tanks; and don't flush toilets unnecessarily. The less
amount of water that flows through your system, the less work your septic system has
to do. These practices will also help you save money on your water bill!
In summary, failing septic systems can cause a serious'health threat to your family and
neighbors and can degrade both surface and ground waters. However, there are some
simple, easy, and low-cost practices that individual home owners can adopt to minimize
the risk of septic system failure. Prevention of septic system failure is ALWAYS less
expensive than replacing a failed septic system!
For more information on the septic systems it? the Virgin Islands and ways to prevent water pollution.
please contact the your local Extension office (St. Thonmas-St. John: 774-0210; St. Croix: 778-0246): the
Department of Planning and Natural Resources (St. Thotnas: 774-3320; St. Croix: 773-0565); or tilhe
Department of Health (St. Thomas-St. John: 774-6880; St. Croix: 773-0565).
IV-4
ALTERNATIVES TO STANDARD SEPTIC SYSTEMS
Tom H.Linnio
Department of Planning and Natural Resources,
St. Thomas, U. S. Virgin Islands
On site treatment of domestic and commercial wastewaters has
been and is today a major topic involving the health and
environmental well being of the community The United States
Virgin Islands has tremendous contribution to non-point source
pollution from the current treatment or lack of adequate
treatment of domestic and commercial waste water. Of
particular concern for the Virgin Islands is the excessive
nutrient loading from phosphates and nitrates of the costal
waters resulting in the death of reef systems due to algal
growth.
The de facto "standard septic system" in the United States
Virgin islands is a septic tank with a minimal if not totally
unacceptable leach pit. Leach fields are very rarely used, to
the point of being almost unheard of. The dominant soils of
the Virgin islands are clays or soils with a high clay
content, often with moderate to steep slopes. Although the
Virgin Island Rules and Regulations has a section on
Percolation tests, specifically T.19, Section 1404-91,
percolation tests are rarely if ever performed. This lack of
performance of percolation tests results in improper
evaluation, design, sizing, and placement of on site
wastewater treatment. One could say with a fair degree of
confidence that the majority of the "standard septic systems"
in the Virgin Islands are not functioning properly, if
functioning at all, as far as treatment of waste waters are
concerned. With the majority of soils in the Territory being
thin with very poor adsorption qualities and moderate to steep
slopes, no development involving proposed on site wastewater
treatment should be permitted without'verifiable percolation
test, proper design and siting of wastewater' treatment
structures. The need for percolation tests and proper
wastewater treatment design, sizing and placement based on the
test can not be over stated.
Another factor that compounds the wide. spread -improper use of
leach pits is the lack of maintenance of the -septic tanks.-
The normal maintenance of a septic tank requires periodic
cleaning to remove solids. This is not a standard practice in
the Territory. When solids move into the leach pit, the pit
becomes clogged and stops functioning as an absorption
structure and becomes a cess pool. This results in an increase
U in down slope nutrient loading, contamination of ground water
and a potential major health risk.
IV-5
This problem 3is not limited to leach pits alone. Generally all
systems with septic tanks and absorption structures must haveI
the tanks maintained and cleaned to avoid movement of solids
to the absorption structures. Failure to properly clean out
septic tanks will cause clogging and plugging of the
absorption structure which are then ruined and must be
replaced, often at a great expense.
There are no maintenance free wastewater treatment systems.
Having so far discussed some aspects of the "standard septic
systems" current in the Territory, I shall now discuss briefly
some alternatives. I must begin by stating the obvious that
the best alternative is a well run and maintained system of
sewers and treatment plants. But since that is not
foreseeable, I will focus on some on site alternatives. A
review of existing resource materials available in theI
territories was to say the least, rather disappointing.
Luckily there is the EPA Small Flows Clearinghouse. The Small
Flows Clearinghouse was established in 1977 by legislationI
under the Clean Waters Act as a national information center
for (among other related topics) alternative sewage
technologies. You can find in the back of this presentation a
current listing and order form for Small flows products. Also
in the back you will find a short glossary of terms often used
in septic wastewater treatment.
Serial Distribution for sloping ground.
This is a modified tile field system, where based on
percolation test results a series of absorption f ields areU
laid laterally with slope contours and tied together witha
series of distribution drop boxes. This system has the
advantage of being able to adjust to site conditions, the3
leach lines can be of varying lengths. The trench increase
absorption areas versus a leach pit. This system can be seen
as a demand system since the various absorption trenches come
in to play as a function of the load on the system. In the dryI
season only the upper trenches may be in use, where as in the
wet season the whole system might cam into play. This allows
at least part of the system some resting periods. The systemI
is easily expandable by the addition of drop boxes and
trenches. The system is fail-safe. If the septic tank is not
properly clean only the first trenches will plug and fail, the3
whole system will not be ruined. I feel this system has great
potential in the Territory, if properly des igned to. the soil
condition on site.3
Wisconsin mound or Transvap Soil Absorption System
This system is a modified tile field system that is placed
above existing grade. This system might be of use where soil
and or site conditions restrict use of sub-surface absorption
systems.
The system relies on selected sand and soil fill to treat
IV-6I
septic tank effluent. Basically a tile field is laid in a
sand and soil bed above original grade. The amount and depth
of bed area required depends on site soil conditions and
depth, depth of water table and or bedrock, quality of the
fill material, waste water volume (loading), and other site
and use related factors. The bed or mound should be long and
narrow. This system may have the disadvantage of needed a sump
pump, if the septic tank is below the mound or bed elevation.
This system may have some positive limited use in the
Territory for some very difficult sites.
Sand Filtration
The use of sand filters may be adapted for many types of
systems such as surface, subsurface, intermittent, and demand
flow. All system must have properly selected sand beds of 24
to 30 inches deep to filter, oxidize and degrade the secondary
treated sewage. Surface sand filters generally are a system
that irrigate the secondary treated sewage (grey water) over
a sand bed. Subsurface filters are generally a tile field over
the sand bed, this system may have a separate lower tile
field under the upper tile field and sand filter leading to a
separate leaching field or even to a sewer. Intermittent sand
filter feed the sand bed in controlled doses, by timed
pumping, dose buckets, siphons or other methods. Intermittent
system can be either surface or subsurface type. Sand filter
can be very useful in soils where percolation tests show
restrictions. The sizing and siting of the sand filter will
be determined by the site soil characteristics, depth to water
table, use, and loading among other factors. The proper
selection of sand in size and type is critical as in the use
of filtration matting to avoid clogging by particles from
surrounding Soils. The use of sand filter has high potential
in the Territory.
Composting Toilets
The composting toilet system is a self 'contained system which
is usually dry with some models using a foam flush. The
wastes is collected inside the composting unit, or goes to an
outside composting tank. Some units with outdoor composting
tanks are designed so as to be solar driven. In either system
the composting tank is vented to minimize odor. With the use
of selected microbes, the waste is degraded to a humus. This
system has been successfully used in the Territory,
particularly on St John. one draw back seems to be a problem
with cockroaches, therefore I would recommend if the system is
to be used that the outside composting tank type with a good
seal between outside and inside be used.
Aerobic Dicrester
Aerobic digester are generally special subsurface
secondary treatment tanks into which ambient air is
IV-7
pumped or compressed to supply respiratory oxygen for ae robic
bacteria. The function of the aerobic bacteria is to degrade
the secondary wastewater. The systems can be as simple as
just an air pump and an emitter, or can have rotation
biological contact drums, paddles, impellers, which are
powered by the air pump or compressor before the air goes toI
the emitters. Aerobic digester can be very useful in
decreasing the biological oxygen demand (SOD) before the
wastewater goes to-1he leach field or pit. This can allow, ifI
properly designed and sized a smaller leach field than might
be otherwise required. Aerobic digesters also can be used
increase the useful life of a leach field. Many of these
digester come as pre-made packages, often made of fiber glass
for ease of installation. They do require a power source to
run the air pumps or compressors. Some unit use solar panels
and batteries to supply the power to the pump or compressor.I
This type of technology has good potential for use in the
Virgin Islands.
Anaerobic Dicresters
Anaerobic digesters relay on anaerobic bacteria to degrade the
wastewater. Anaerobic bacteria generally must have an
environment lacking in "free" of molecular oxygen. This type
of digester often is a below ground treatment tank which is
packed with a contact medium, often red wood bark. AnaerobicI
digester can also be above ground, indeed this type of
digester is common used in marine service on boat, ships, off
shore drilling platforms'etc. One advantage for costal orI
marine use in the anaerobic bacteria are capable of
denitrif action, the is to say they can degrade common nitrogen
compounds. Nitrogen compound such as nitrates and nitrites
are very harmful sources of nutrient loading, killing reefs byI
causing algal blooms. Aerobic bacteria are not known for
denitrifaction where as anaerobic bacteria are. This system
is not uncommon in the Territory though one can not say it isI
widely used. Some years ago the Government did use this system
for facilities near the coast and off the sewer lines. rt had
good initial success, but failed in the end from lack of
proper maintenance. This system has great potential in the
Territory for areas with clay soils, coastal area, areas with
high water tables, and small lots. This type of system does
require some more ongoing maintenance than some other systems.
Subsurface Emitters with TreesI
This system uses a modified leaching and irrigation system
where emitters packed with red wood bark are place and a
tree is planted above. This system works with the
evapotranspiration increase that the planted trees supplies.
The redwood bark packing from reports not only increases the
biological contact area, but also appears to prevent the treeI
roots from growing into the emitter and clogging the system.
IV-8I
This is a fairly new system with good results so far.
This system may be a good alternative to the current
practice, particularly of hotels, of using sprinkler for
irrigation of gray water.
Wetlands Systems
This is another fairly new technology that has been
tested and proven on both large and small scale. This is
a secondary treatment where the primarily treated waste
water is feed into an artificial wetland system. For
residential or small scale commercial uses a two cell
wetland with liners is currently used for treatment. The
cells have specialized distribution, gravel or gravel and
sand bed and use reeds and other wetland plants. Another
cell which is not lined can be used for leach or the
treated water may go to a leach field, or even be
discharged in to a waterway if permitted. This system is
solar driven, that is to say the sun supplies the energy
to run this system This system works with biological
degradation, biological uptake, evapotranspiration and if
properly maintained should decrease nitrogen and
phosphate compounds. If the system is properly designed,
sized and maintained there is no ponding, so mosquitos
should not be a problem This system is currently under
study by EPA and the Tennessee Valley Authority and has
been successfully used in many areas.. I f eel this
system has great potential for use in the Territory.
* Green House Ecosystems
This system can be viewed as a combination of a marsh or
wetlands with aquiculture and is another solar drive
system which also uses pumped or compressed air. In this
system wastewater is f irst equalized, then clarif ied and
oxygenated. The wastewater is then pumped to a series of
solar silos, then to marsh cells -from which the water is
treated by ultra violet lights and finally discharged.
The plants are run in parallel in case of failure due to
poisoning from improper chemical that might be place into
the waste water. With a parallel system if one leg is
knock out the other leg can supply the end microorganism,
organism and plants. This system uses biodegradation,
biological uptake evapotranspiration and should be able
to treat nitrogen and phosphate compound if properly run.
This system has been proven on both fairly large and
small scales and may have good application in the
Territory. It is not though a system for the average
single homeowner.
incineration
Incineration of toilet waste product has some
limited application, in this system toilet wastes
TV-9
are incinerated using LP gas, propane or electricity. It is
not meant to deal with other bathroom or kitchen waste water.
Most often used in summer camps and similar applications, this
system invented in the 1930's has never been widely used.
There are some other types systems such as recirculating I
toilets, electrolysis, water hyacinth basins which are used
sometimes. I mention these here in passing. The systems that
I have presented I feel have better chances of application in
the Territory.
IV-10
IV-10 "i ':. ·
INTRODUCTION
SEP77C SYSTEM STUDY
Man's carelessness In the management of his own excreta can result in a number of diseases
FOR THE ViRGIN ISLANDS as pathogens from an infected person find their way by water, food, or soi to another
human being. The firt Ulne of defense would appear to be simple; manage our waste so
that none of It reaches drinking water or food supplies and isolate it from the ground
surface where It is accessible to animals, including insects and birds, which can be direct
carriers of pathogens.
1Wa llswAd DCparnnt of twbt and Naftral R80oocaIs Since its introduction in the United States in 1880, septic tank systems have become the
Y.ph, IS omnd. Corleervalon Dfbt t most widely used method of on-site sewage disposal. Although the concept and design of
a a s o Coun Cidthe septic tank/soil absorption system are relatively simple, the system Involves complex
1tgh IW -anx C.oea rwe tbn anOd DevOeyptflentfl!/t ) c unC physical, chemical, and biological processes. Performance is essentially a function of the
design of the system components, construction techniques employed, characteristics of the
wastes, rate of hydraulic loading, climate, aerial geology and topography, physical and
chemical composition of the soil mantle, and care given to periodic maintenance (USEPA,
INTErlM REPORT PART 1 (RelVded) 1977).
INTERIM REPORT PART 2 (D rd ff) The septic system's recent reputation as a major contributor to environmental pollution is
not the result of the system's Inadequacies, but rather the result of a misuse of this disposal
practice. The septic tank system is a combination of unit processes which were Initially
intended for rural farm families. Its widespread use in suburban areas has resulted in many
installations where the septic system has been squeezed onto small lots, in soils of limited
suitability and has been neglected by the home owner, The septic tank/soil absorption
BRAFT ABRIDGED EDITION system has demonstrated to be ill-fitted under these adverse circumstances.
For Presentation at the First Annual Virgin For residences on the U.S. Virgin Islands, the conventional septic tank/soil absorption
Islands Conference on Nonpoint Source Pollution system consists of two (2) major components, a water tight compartment (septic tank) and
October 5, 1993 a provision for liquid effluent discharges to the subsoil (leaching trenches or seepage pits).
The septic tank serves simultaneously as a separation unit and as a storage and digestion
unit for the retained scum and sludge. A leaching structure is used to dispense the liquid
Presented By Barry W. Kimball P.E. septic tank effluent Into the soil, and therefore must be constructed In soils capable of
EXCERPTS-FROM SEPTEMBER 1993 REPORT accepting and dispersing the liquid.
The original Intent of this study was to find ways to improve upon the conventional septic
tank/soil absorption system and septic system regulations to bring them into compliance
with the usual standards for design and construction for on-site disposal of sewage effluent.
The strategy in performing this study was to assume that subsurface soil absorption (disposal
trenches, beds, seepage pits) Is the preferred on-shite disposal option because of Its reliability
with a minimal amount of maintenance. The process was then to analyze the soils,
fhahaff" 0SuJ ")Anq ALoad Planli'g A D66191 topography, geology, and other characteristics of the Islands so that the regulations could
tI11.1nM * Sur_4ng * Lone PIonfl) & Ds19n , he customized to fit the specific circumstances. In those areas where the site characteristics
St Tamos. U.S.V.I. 00802
are unsuitable for soil absorption systems, alternative methods would be investigated as a
last resort for on-site disposal since these aJternatives are typically the most costly to A L HARACTERISTICS OF T
construct and require a great deal more maintenance and supervision than soil absorption
systems. U.S. VIRGIN ISLANDS
Now that the analysis of the Islands characteristics is completed, we have found that the vwst
majority of the Islands' land areas are unsuitable for soil absorption systems. We have also TOPOGRAPHY
found that thousands of the septic systems currently in operation have been located in areas
that are inappropriate for subsurface disposal and represent not only a hazard to the St. Thomas
environment, but more Importantly, a risk to the public's health. There is a great lack of
understanding among regulators, home owners, developers, and contractors about how septic St. Thomas has an extremely irregular coastline and is very hilly with practically no flatland.
systems operate. Examples of this misunderstanding is the acceptance of seepage pits The highest ills are generally found near the center of the Island, with Crown Mountain
constructed directly In fractured bedrock and leaching trenches installed In impervious clays, at 1,550 feet the highest point The Island Is relaidvely small and many of the peaks rise
both of which are located on small lots In densely populated neighborbhoods. Very few above 1,000 feet This results in rather steep slopes over all the Island, so that ralnhfa
people on the Islands understand, that for soil absorption septic systems to operate properly, runoff is quite rapid and there are no permanent streams or rivers.
septic tank effluent must be filtered through at least 2 to 4 feet of pervious soils before it
can be discharged to the environment. This basic tenet of septic system design is what St. John
makes the traditional soil absorption system unsuitable for almost all locations on the Virgin
Islands. Most of the land surface does not have 2 to 4 feet of soil or, in areas where there Like St. Thomas, St. John has an extremely irregular shoreline and a very hilly topography,
are deep soils, it is typically impervious. It has a number of peaks over 1.000 feet topped by Bordeaux Mountain at 1,297 feet in the
eastern portion of the Island. Slopes are quite steep over all of the island, and there are
The focus of this report is now to explain and justify the reasons why the conventional very few areas of flatland. There are no permanent rivers or creeks.
:C subsurface disposal' system is inappropriate for almost all developable areas and offer
alterative disposal options that may be suitable. St. Croix
The report's recommendations are expected to stimulate discussion on the different St. Croix is the largest of the three U.S. Virgin Islands. The topography is somewhat
approaches for regulating the installation and use of sewage disposal systems. Readers are different from the other two with a broad expanse of low, relatively fitland running along
encouraged to express their views and opinions in writing to the Department of Planning the southern two-thirds of the Island. The North End Range, a series of hill, ranging in
and Natural Resources. The Department has indicated that it will fully evaluate all elevation from about 500 feet to more than 1,000 feet topped by Mount Eagle at 1.165 feet
comments prior to formulating revisions to the Regulations. Comments may be submitted runs along the northern coast. East End Range of St. Croix is another group of slightly
to the following: lower hills with a maximum elevation of about 860 feet found on the eastern end of the
island. The area covered by hills on St. Croix results in rather steep slopes down to the
Adrian Schottroff, Chairman NPS Caribbean in the north and to the level areas to the south.
DPNR/DEP
GEOLOGY
Mario Morales
RC&D.Coordinator, SCS The U.S. VIrgin Islands are located at the eastern end of the Greater Antilles island chain
and are comprised of the three major islands of St Croix, St. Thomas and St. John as well
as some 50 smaller islands and cays. St. Croix is the largest of the islands (85 square miles). -
It lies about 40 miles south-southeast of Puerto Rico and about 40 mlles south of St.
Thomas (30 square miles). St Thomas lies approximately 40 miles east of Puerto Rico and
25 miles west of St John (19 square miles).
- -- - l - - - - - -- -
The Eagle Mountain Volcanics of SL Croix has been intruded by a large mass of gabbro in
the Fountain Valley region of the North Side Range nd by a similar mass or doirit in the Soil wetness conditions or drainage casses refers to the depth within a soi that saturation
East End Range between Great Pond and Southgate Pond During late Cretaceous or Ear near saturation by the ound water table is encountered and is an important design
or near saturation by the ground water table is encountered and is an important design
Tertiary age. Up to this time The Mount Eagle Volcnics was one continuous ridge, consideration for septic systems in may parts of the country. Due to the hydrogeologic
Sometime during Early to Middle Terdutay age St Crox's central valley was created by a conditions of the U.S. Virgin Islands however, ground water tables rarely approach the
downthrown block (grabben) as result of normal faulting and St Croix consisted of two
islands Separated by a deep marine basin in which is mucb as 7,W0 feet of cl ayey ground surface and hi. not an important tool in land use planning decisions with the
islands separated by a deep nrine basin in which as much as 7,000 feet of clayey exception of a few soil series which will be noted later in this section.
"''s'OstteuYmdOLAtatndsisplnt r alaexception of a few sol ieries which will be noted later in this section.
sediments lown uas the Jelousy Formantion. Alternating deposiuts of planktonic material and
sediment gravity eows which accumulated In deep water during Oligocene and Miocene Analysis of the physical characteristics of the Virgin Islands soil resources indicates three
age form the limestones and math of the nhll Formation. The Klngshill Formation major categories of soil groupings which, with a few exceptions, should act similarly with
(known locally as Caleche) extends across the south and central plains of St. Croix. Along respect to the design and operation of septic systems These categories are closely related
the southwestern coastal plain, thin deposits of shallow water benthic organisms overlap the to the parent materials in which the soils have developed and are designated as Volcanic,
Kingshfll Formntion Calcarious Marine Sediment, and Alluvium. Table 2 presents a soil catena relationship for
the proposed soil series in which they have been sorted based on their parent materials and
Recent geologic processes occurring on the U.S. Virgin Islands consist primarily of surface the proposed soil respee in tbhey h av e been sorte o on It should bparent materias and
weathering of the bedrock formations, erosion. and the deposition of aluvwiu along then arranged with respect to their typical landscape position. It should be noted that the
iwentering of the bedrock a nn tdns eroeamns and the deposition of aauvsuta along aucus and Sugar Beach series have been placed in the Alluvium category for the purposes
southeasternt stream chf annth el North in costal embayment and as alluvil fares along he of this discussion. aucus eonsts of beach deposits ofcalcarious marine sands while Sugar
southeaster base of the North End Rane of SL Croix. These processes have configured Beach develops on deep organic (muck) deposits. Generalized soil maps showing the
he landscape of the islands and hasdevel fored the arent material base upon which the soils distribution of these categories for St Thomas, SL John and St. Croix are presented as
of the U.S. Virgin Islands have developed. Figures 1, 2, 3. respectively, A, the new soil survey maps are not available, these maps have
SOILS been prepared using geologic maps of the islands showing the spatial relationships of the
I-L· parent material groups.
c Soils of the U.S. Virgin Islands have been characterized by SOIL SURVEY, VIRGIN
IStANDS OF THE UNITED STATES published by the United States Department of
Agrculture, Soil Conservation Service in August of 1970. This publication contains Soils developed from volcanic parent materials are the most wide-spread category on St.
descriptions of the soil types identified and mapped by the soil survey, physical data. Thomas. St. John and in the North End and East End Ranges of St. Croix. For the most
interpretations of their suitability for various uses, and maps at a scale of 1:1840 depicting part they have formed in thin mantles (less than two feet) of materials weathered from the
their lateral extent Although this document has been a valuable tool for land use planning. underlying volcanc bedrock formations nd occupy slopes of up to 75f6 or more with slopes
its inforation is old and has become outdated with respect to the current understanding in excess of 359b being very common. The volcanic parent materials weather to form highly
of the U.S. Virgin islands soil resources. structured soils with textures of clay and clay loam, usually with a gravelly or very gravelly
The USDA Soil Conservation Service is currently in the process of a re.classification and component.
correlation of the soil resources of all the islands. Some of the soil series recognized by the Montmorillonite clays (high shrink swell capacities) are mineralogical coponents of the
1970 publication will continue to be recognized through this process. Many of the old soil Jelousy ParasoL Sussannaberg and Fredriksdal series. Areas of volcanic parent materials
series, however, will be discontinued and new series formulated to more accurately describeerology a noted on the eneried sil maps.
the charaterdtics of these resources. Field mapping of St. Croix and St. John has been
completed and mapping is in process on St. Thomas at the time of this report. Permeability for the soils in this category is reported to be moderate with the exception of
Unfortunately, detailed maps will not be completed or available fdr use in this study. the soils with Mntmorillonite clay which have slow permeabilities. Exceptlors within this
Indications ae that they will be available for use in the near future. In anticipation of the category are the Parasol ad Jelousy soils which have developed over the gabbro and diorit
availability of this information. this study will use the information that is currently available intrusions on St. Croix and dp and very deep respectively to the underlying bedrock
for the new Soil Survey. Table I lists the names of the soil series proposed for this survey. formations.
formations.
Calcarious Marine Soils:
Soils developed from calcarious marine sediments are Arawak. Sion and Hessleberg. They
have developed in parent materials derived from the calcarious marine sediments of the
Kingshill Formation found on St Croix. Arawak is a shallow soil located on the summits
and upper side slopes of the limestone hills and are gende to very steeply sloping (up to
75%). Sion found on the lower side slopes and valley floors of the limestone deposits, is
very deep and gentler sloping (0-12%). Hessleberg has developed on shallow marine
terraces along the southeastern shore of St. Croix and is distinguishable due to a hard
petroalcie layer present within 20 to 30 inches of the soil surface. These soils are underlain
by a soft limestone marl which is known locally as Calecbe. Permeability of these soils is
moderate. Textures are clayey.
Soils which have formed in recent alluvial deposits on the islands can be separated into two
groups, those having development potential and those that do not. The latter group is
comprised of soils associated with natural resources that have significant value to the benefit
of the general public and should be preserved. These ares include mangrove swamps, salt
marshes, salt ponds. tidal flau, beaches, and areas with high water tables adjacent to these
resources and In gut floodplains. Soil series typically found in these areas include Sugar
Beach, Sandy Point Jaucus, Solitude, Cornhill, and Carib respectively. Any of the other
series in the alluvium category may also be included in this group when they arc located
within or directly adjacent to drainageways, locally known as 'gut. T. THOMA5
The remaining soils in this category have developed in sediments on alluvial fans, terraces. General Soil Map LECEND.
plains and lower side slopes. Cinnamon and Glynn are formed in fine textured sediments
from extrusive volcanic rocks which overly stratified fine to coarse textured sediments. Alluvium Sols
Hogensborg is formed in clayey sediments with Montmorillonite mineralogy derived from
intrusive volcanic rocks. specifically the gabbro and dorite intrusions found in the North End Ltmestone Solts
and East End Ranges respectively on St. Croix.
:......." Voe.nI SC s wtllh Montmorlonite
Clay tlnerolooy
mI - - - - - - -------
- - - - - - - - - - - - - - - - - - - ...............
Alu%
............ ..... . ...... .......
S..........
General Soil Map . .eea ..i .a i .....
t-n S T . J O H N G n eral 5ii MapLEGEND, kctn
Alluvium 5os km el s with Mafltmoriffouite
A uv wtm boi C40y Minerology
[1:::]Voi lcai 5)ol5 Volcanic $oIh
Vigure F 2 j7] anic Sods wIth Montmiorillomiie V olcani Sols la wt-hirog Mlo Amorigolte
10 milligrams per liter (mg/I). Nitrate nitrogen levels above I to 2 mg/I are typically
GIROUNDWATER: considered to bt elevated above natural background levels.
Investigation into the groundwater quality of the U.S. Virgin Islands has been conducted by
Groundwater in the U.S. Virgin Islands is a limited resource which has been estimated by Geraghty & Miller (April 1983), the U.S. Geological Survey (Garcia and Canoy, 1984 and)
the U.S. Geological Society to supply approximately 20% of the total water needs of the and others. Geraghty & Miller collected and analyzed Inorganic chemical quality data
islands population and industry (Torres-Sierra and Rodriguez.Alonso 1986). The from several sources within the Fairplains and Barton Spot well fields as well as from 78
development and operation of groundwater production wells has been recognized as the private wells on SL Croix. Inorganic chemical quality was also gathered from vrsenDwells
most cost effective source of drinking water available on the islands (C2HM Hill. 1983) and in the Turpentire Run basin on St. Thomas. They reported nitrate nitrogen levels of 35
as water demand increases it is likely that pressured to develop groundwater sources to their to 4.6 mg/l in the Fairplains wells, 3.8 to 7.4 mg/I In the Barron Spot wes, and several
fullest capacity will also increase. Investigation into the extent, quantity and quality of other areas on St Croix with levels which approach and In some cases exceed the 10 mg/I
groundwater aquifers has received considerable attention by the U.S. Geological Survey, the maximum contaminant level establish by EPA. Four wells In the Turpentine Run Basin on
Water Resources Research Institute of the University of the Virgin Islands and several St. Thomas were reported to have nitrate nitrogen levels In excess of 10 mg/i with four
private consulting firms In conjunction with governmental agencies. of the other wells sampled having levels between 3 and 5 mg//L
Concerns for public health have prompted the U.S. Environmental Protection Agency to Garcia and Canoy collected and analyzed water samples from 8 wells on St. Crox, 7 wells
establish primary and secondary water quality standards for drinking water supplies. on SL Thomas, and 4 wells on St. John for Inorganic ehemical quality as well as fecal
Contaminants of primary concern that are :introduced into the environment from the coliform and fecal streptococci bacteria. Nitrate nitrogen exceeded 1.0 mg/l in ten of the
application ofwaste-water are pathogenic organisms (bacteria, viruses, and parasites), nitrate wells sampled with two of the wells being in excess of 5 mg/l and ma of the samples being
nitrogen, and synthetic organic compounds. Pathogenic or disease causing organisms are below 10 mg/I. Fecal bactcrl were detected In all but one of the wells with feca
introduced through the feces of individuals who are either infected with the disease or are streptococci being detected as high as 5,800 colonies per 100 milliters of sample.
carriers. Nitrates are formed from the mineralization and nitrification of organic
compounds found in waste-water by aerobic microbes. Synthetic organic compounds are Ln 1986 Knudsen conducted a study to evaluate the presence of water borne pathogens In
contained in cleaning agents and other man-made products which are being commonly used the various drinking water sources of the U.S. Virgin Islinds and the ability of standard
In the house-hold. A more thorough discussion of these contaminants, their modification testing requirements to detect them. Samples were collected from cisterns, wells and points
and disposition through septic system operation is contained elsewhere in this report. along the public water system. Human pathogenic bacteria were found to be prsentn all
of the 16 sampling points with fecal streptococcus being present in all but one sampling
The proper design and construction of septic systems is effective in the removal of point.
pathogens through soil treatment of waste-water prior to its discharge to the underlying N
water table. The presence of fecal bacteria within a groundwater aquifer is a prime indicator In 1986 the U.S. eological Society compiled chemical water quality analyses of water
that direct connection/s between the aquifer and inadequately operating septic system/s samples collected between 1965 and 1985 from the principle aqulfenrs of the US. VIrgin
can exist. A saturated flow zone berween the disposal mechanism (trench, seepage, etc.) Islands (Zack Rodriupez-Alonso and Roman-Mau 1986). A total of 169 samples were
and the water table or fractured bedrock formations are the most common avenues cited analyzed for nitrate nitrogen; 21 from the Klngshill aquifer on St Croix, 140 from volcanie
In the literature for the migration of pathogens over long distances, The maximum bedrock aquifers and 8 from coastal embavment aquifers. 759 of the samples collected
eontaminant level established for bacterial in dHnking water is one colony per 100 from the Klngshill aquifer are reported to have nitrate nitrogen levels In excess of2 mg/i
milligrams of water. with 509% being in excess of 8 mll/I and approximately 40% exceeding 10 mg/L Of the
volcanic bedrock samples, 50% exceed 2 mg/i and approximately 30% exceed 10 mg/L
Nitrates, on the other hand, are generated from the application of waste-water through Coastal embayment aquifers exhibited better water quality with respect to nitrate nitrogen
conventional septic system operation, regardless of design and construction considerations, with less than 20% of the samples exceeding I mg/I.
and surface discharge of improperly treated waste.water. Nitrate levels within an aquifer
Is determined by the density of development which discharges Its waste.water within the Most authbts reviewed have cited septic system practices in the U.S. Virgin Islands as
catchment area supplying recharge to the aquifer and the anount and quality of water contamination sources and- a threat to the quality of the islands groundwater resources.
rechurging the aquifer, Nitrate nitrogen levels within a aquifer, therefore, is a useful tool
In assessing development impacts to groundwater quality and the, level of development
controls necessary to maintain groundwater quality level within acceptable standards. The
maximum contaminant level for nitrate nitrogen in drinking water has been established at
- - - - -- -- -- - - -
EVAPORATION RAINFALL
The Bethlehem Upper New Works. SL Croix. gaging station is the only location found on Annual rainfall values differ from location to location with higher elevations generally receiving
the Virgin Islands that measures evaporation with any consistency. l5ata from this station greater amounts. On St. Thomas and St. John, annual averages of between 40 and 60 inches.
shows that avenge monthly evaporation varies from 4 l/r per month in the winter to On St. Croix, them Is a more noticeable variation from place to place. This Island has the
almost r in the summer month The yearly evaporation average is close to 80 inches per greatest annual rainfltl, in excess of 30 inches in the northwestern comer. A narrow finger of
year. Normal rainfall usually equals or exceeds evaporation in the months of October and between 25 and 35 Inches extends northeast to southwest over the fatlands south of the hills in
November. the western portion of the Island. Records available for the three Wands indicate a relatively
wet-relatvely dry season distribution, but It Is not sharply defined. The relatively dry period
extends fom about December through June. Occasionally, quite heavy rainfall occurs during
TOTAL EVAPORATION AMOUNTS (inches) the so-called drier months. The driest month on S. Thomas and St John usually Is February
BETHLEHEM UPPER NEW WORKS, ST. CROIX U.S.V.I. or Much and the wettest month September or October. On St. Croix, the month with the
heaviest rainfall, on the avenge, ranges from September through November.
R AlFlDEVIRGIN ISLANDS PRECIPITATION NORMALS (INCHES)
1985 539 635 6.76 8.38 8.20 831 9.59 - 7.Z3 - - 4.57
1 .3 .68.79.9 - 7M--STATION IJN I EB I MAR I APR I MAY JUN I JUL AUG SEP OCT INOV DEC IANN
1906 5.57 638 - 7.13 - 839 7.98 7.73 7.03 5.77 4. .
1987 68 4.74 7.60 6:61 6.49 - 6.84 6.63 8.21 6.50 51 ----5.2. )A.' Il l 3:1 1:, 1:;.: 1:1:, 1:11 : .0 3:11
1988 5.16 5.70 7.72 7.15 - 5.10 7.21 - - - - 44 sISION ":., i 1: : 1:11 3,,I5 ! 2.59 s:s: 1 1:11, 1..ss AI 1:11 1:48
4("oIsA Ml0:.5 .51:11 41.1 . ON 5.: 41 , I I N 45.54 :1':I1:. 1 ,
1989 534 - 6.2 n - 8.08 - 6.79 7?S - - -.. C.I.M440358 1. I' A
M - 6.62 6.98 7.75 -- - - - - .82 RNA
t9 4flU 1:1? 7:17 :: i lll 5:1, *:sI 1:711 7:71 2:17 3:34 1:27 3:27' 1:11Is:": - I :11 I' I 1: ., :I, a
1991 3.43 5.28 - 837 733 - 9.09 7.84 857 - 7.02 - 13 0 L'.1 1: $I 1 . . 1; 1 45 . 1 11 .I
AVOS 5.50 5.69 6.98 7.44 7.57 7.29 7.91 7.43 7.76 6.14 5.64 A-51 16-141. - VD I A% 1:11' IAI 1:11 1:11 1:11; 1:14, H'I 3'. '. I1:145k .5 49985 4.5 I, .b t
3881( CI nmologicol oleso a.5.al a.nmc .4 . . 3: ?AI7 1:h IT 33 oU 1 1:4 1:711 3: Is
(451V 0454. 7?7 I 1 1:71 " , I'AN 1 A.ss Ad 7:11 '1 1:1.1 1:, :3 17
Indicals:4 (11 monfl wher e Womto is amaial L"L dst %1 n1 :..111; is 2 :11 s.", i :22 1:11 111 1:11 1:71 2:7 :11 3:217 I41.1A
IN, 445 1% 13:11 U1, 1A, 1 1:16' !:I 11 3:11 `JI :11 .13 11 1:1! 3:2 I 7s1:37
- Indicates mossdss isere inI rmation is n available. 44l 71272k 3:....:IN Is1:1!'UI 1:1I 3:11 7:12 lii 2: 4,2:33 711 4.
.4vto 54
U0 '(10 I N 2 L3 :11 1:7 '117 :1I 2:11 I: 1:11' I:3R1: :1 213 1 )-? "1: I I,
Fro. precipitat ion aan lnora S am 'Clma t ological Daa V' as published by U.S. Department of
Commerc, Nbaonnoa Oceanographic and Atoospheric AdminiAtro: ion
GROUNDWA'ER RECHARGE QN-SITE SEPTIC DISPOSAL SYSTEMS
The rate of ground water recharge in the U.S, Virgin Islands is an important consideration GEERAL
in the management of appropriate septic system densities. Rainfall infiltration which is able
to reach the water table is the primary source of replenishment of the various groundwater Septic systems have long been believed to be an efficient and cost-efctive mra of
aqulers followed by septic systems operation and surface discharges from sewer treatment disposing of domestic wastewater and have been relied on beavily to support residential
plants. growth in urban ad rural areas not served by municipal wastewater collection and
treatment systems. Until recently there has been relatively Uttle untmdersmanding of the
The U.S. Geological Society has prepared a water budget for the Islands which indicatces
that 94% of the rainfall is lost to evaporation and transpiration by plants. 3% is lost to cotamitnantspresentindomesticwastewaterandthesoiltreatmrentmechan'sthat modify
surface water runoff with the remaining 3%o being discharged to the groundwat er table. This its qualiy before reaching our ground water and surface water resoures. Septic systems
amounts to a little more tha n one inch of rainfall per yea being intro duced into the owater were often thought of as temporary solutions to wastewater disposal thatwould operate only
tnasble to a ic more tban one incb of rainfaU per yar beiog inoduced into th vatr until municipal services were made available, As a result many areas In the continental U.S.
which saw high growth rates and dense development In the 40, SOs and 60s have
experienced a serious degradation of the quality of their drinking water supplies from septic
system operation practices.
Within the past 15 to 20 years a tremendous volume of research has investigated these
issues. Although by no means complete, the literature is supportive of the pretext that
septic systems are a viable alternative in areas where public sewers and wastewater
treatment systems ae not available or economically feasible. They will operate effectively
if they are properly designed, situated in areas suitable for operation used only for the
purposes for which they were designed, and given periodic maintenance.
This section presents the current understanding of the treatment mechanisms that occur as
septic tank effluent passes through a soil medium and the resultant effects on ground water
and surface water quality.
WASTEWATER CHARACTERISTICS
'nle design criteria for septic systems, effectiveness of the soil treatment mechanisms, and
the resultant pollutant load placed on water resources Is in parut a function of the
characteristics of the wastewater being applied. Wastewater characteristics should be
evaluated In two categories: quantity of the wastewater generated and Its quality. Both
components can vary greatly and are dependent upon the type of use.
Ouantity of wastewater has been characterized for a wide variety of uses and can be found
in most manuals or codes which characterize septic system design parameters. It is
important to recognize that the design flow figures presented in many of these sources
incorporate pealdng factors to insure that a septic system can accommodate short periods
of higher than average water use. While it is important to sitze the septic system
components to accommodate the occurrence of peak water usage, average daily flow figures
represent long term trends in water use and are more appropriate for use in evaluating
impacts from septic system operation. Literature references indicate that the average daily
flow for residential wastewater is in the range of 45 to 60 gallons per capita per day (gpcd).
- - m - - -- -- - - ---
Synthetic Organic Compounds: Synthetic organic compounds are being detected in
domestic wastewater more frequently than ever before. They are contained in Removal of pathogenic organisms in the septic tank processes is a function of detention time and
cleaning agents, gasoline, and other min-made products which are people flush down organism reaction to the oxygen deficient conditions within the tank. Organisms have a
toile and drains. Many synthetic organic compounds are believed to be tendency to become associated with solids and can become incorporated in the sludge. This,
carcinogenic, and only require very low concentrations to present a public health coupled with the presence of an anaerobic environment not suited to the survival of pathogens,
concern. Many authors believe that the introduction of these compounds to our has led to reports in the literature of significant removal rates within the septic tank. Although
environment through the use of septic systems may be the greatest threat to our removal rates in excess of 99% have been reported for some organisms, the high levels of
ground water resources in the future. concentration of pathogens present in the wastes of infected individuals would still result In
extremely high numbers of organisms discharged in septic tank effluent. It must be assumed
Other chemical and physical contaminants: In addition to the wastewater constituents noted therefore, that the septic tank is unlikely to remove any organism completely, and that septic
above, chlorides, metals, and specific conductance (an indicator of salts) are tank effluent must be considered capable of transmitting any disease whose pathogenic agent is
groundwater/surface water quality parameters which are impacted by septic systems and present in the raw wastewater.
other development related uses.
SOIL TREATMENT OF EFFLUENT
SEPYTIC TANK
After pretreatment, the septic tank effluent is conveyed to a disposal area where it is applied to
Wastewaters are modified through pretreatment processes which occur in a septic tank prior the soil. The disposal area can be of several different configurations, i.e., leachbeds, trenches,
to being disposed of in the soil. These processes include physical separation followed by seepage pits, etc. The soil treatment processes for each disposal option is the same, differing
anaerobic digestion of the waste matter, only slightly on the method of application used to distribute the effluent over the surface of the
disposal area. The Infiltrative surface between the disposal area and the surrounding soil acts
Septic tanks are buried, watertight structures designed and constructed to receive the as a filter removing the particulate matter and most of the larger microorganisms (bacteria and
wastewater and to provide a desired detention time before passing it on to the soil for parasites).
disposal. Durinl this detention period the 'floatables' in the wastewater (oils, greases, and
some feal coonstitents) float to the top, where they undergo some microbial decomposition As the effluent moves through the receiving soil further treatment is provided through filtration,
and form a floating layer of scum. Settleable solids and partially decomposed sludge adsorption, and microbial utilization. These processes provide the optimum treatment potential
accumulate at the bottom of the tank where they are subjected to microbial decomposition. of a soil when the effluent is allowed to pass through the soil under unsaturated flow conditions
The somewhat clarified liquid remaining between the layers of scum and sludge, 'septic tank and oxygen is present for bio-utilization. At appropriate loading rates the remaining bacteria
effluent' is displaced from the tank as new wastewater is introduced. and viruses are effectively removed, the soils phosphorus retention capacity is maximized, and
the ammonium ions are converted to NO,-N. Very little treatment occurs when the effluent is
The high rate of microbial decomposition or digestion that occurs in the septic tank quickly transmitted through the soil under saturated flow conditions resulting in a high potential for
utlizes any ozy n present in the raw wastewater and the digestion process operates in an bacterial, viral, and other contaminant transport into our ground water and surface water
anaerobic or osygen free environment. Under theie conditions, the organic components of resources.
the wtemter e partially broken down by microbali enzymes, resulting in a chemical
transformation of the nitrogen and phosphorus compounds. The end result being the Distribution:
formation of ammonia (NH3) and orthophosphate (PO4) along with methane gas, hydrogen
sulfide gas and water. At normal pH levels found within septic tank effluent, the ammonia In gravity distribution systems commonly used in the U.S. Virgin Islands effluent Is usually
transforms to the soluble ammonium ion (NH4+)., delivered to the disposal area by gravity from the septic tank, The effluent is distributed over
the disposal area by gravity flow through 4' diameter pipes containing large perforations in
trenches filled with crushed stone or through seepage pits surrounded by stone. If sufficient
receiving soil exists, the organic components of the effluent are filtered out and an organic rich
biological mat or crust is developed which reduces the infiltrative capacity of the soil and creates
a zone of unsaturated flow as the mat creeps across the infiltrative surface. Once full mat Under saturated soil conditions all or nearly all of the pore space is occupied by water and soil
development has occurred the reduced application rate promoted by the restrictiveness of the moisture tensibns are much lower. Water or effluent applied to a saturated soil moves rapidly
organic mat induces unsaturated now conditions in the surrounding soil and the quality of the through the larger pores, reducing the ability of all of the treatment processes described to
soil treatment process increases greatly. In mature systems the effluent typically becomes occur. The application of wastewater in areas with little or no soil treatment zone over
ponded above the mat and the anaerobic environment developed in the septic tank is maintained fractured bedrock can also obviate the occurrence of these treatment processes. In nearly all of
in the disposal area. the studies reporting pathogen contamination from wastewater application to the soU, the point
of application was directly into saturated soil conditions and/or fractured bedrock where no zone
Bacteria: of unsaturated soil had been provided for treatment.
Filtration is the prime mechanism affecting the removal of bacteria from the effluent as it moves Viruses:
through the soil, with the degree of removal being inversely proportional to the size of the soil
particles in the unstructured matrix. The infiltrative surface of the disposal area is very effective Because viruses are very small microorganisms, adsorption rather than filtration Is the primary
in this regard, especially in mature gravity now systems with organic mats that reduce the pore soil treatment mechanism effecting their removal from septic tank effluent. Vlruses a
size available for transmission. Filtration continues to occur within the soil and is assisted by electrically charged colloidal particles whose charge is negative at most soil pH values. They
adsorption in the removal of bacteria. Adsorption occurs when an organism becomes attached are adsorbed by anionic attraction at pH's below and by cationic resins at pH's above their
to the surface of a soil particle by chemical bonding between the surface and the organism. isoelectric (neutrally charged) points. Negatively charged viruses are attracted to rations which
Adsorption takes place on the cation exchange sites present within the soil and the rate of in turn occupy cation exchange sites available on the soil particles. Virus adsorption capacity,
adsorption Is therefore controlled by soil texture and chemistry. Finer textured soils generally therefore, increases as clay content, cation exchange capacity, and speifi surface area
have a greater adsorption capacity than coarser textured soils. increases. Changes in the chemical composition of the soil-water solution, such as Ionic
concentration, pH, and organic matter can affect a soils adsorption capability.
Survival of bacteria within the soil is also an important consideration in the treatment of septic
tank effluent, In order to remove the threat of pathogenic contamination of ground water the As with bacteria, the survival of viruses within the soil Is an important consideration in effluent
microorganisms must be rendered inactive. Soil temperature, pH, moisture state as well as treatment. Again, the soil presents a hostile environment which works to tnder viruses
) antagonistic organisms, soil antibiotics, and the lack of nutrients combine to present a hostile ineffective. Studies indicate that temperature has the greatest effect on survival of viruses with
environment for pathogen survival. inactivation rates increasing as temperature increases.
Moisture state is the single most important factor controlling the removal of bacteria from septic For adsorption to be effective, close contact between soil and virus particles is essential, Waste
tank effluent within the soil. The processes described above are most efficient when they take disposal in soil must be done in a manner so that this contact can occur (6). Soil moisture
place In aerobic unsaturated soil. Under these conditions the larger pore spaces within the soil values and effluent flow velocity or loading rate are the two most Important factors in Insuring
are filled with air and the increased moisture tension holds moisture to the surface of individual that adsorption takes place. High moisture tensions associated with unsaturated soils holdithe
soil particles and within the smaller pore spaces. Septic tank effluent applied to the soil must effluent in close contact with the soil particles while low loading rates provides longer residency.
flow through the smaller pores and over the soil particles, providing a high ratio of surface area times for adsorption to occur. Studies have indicated that unsaturated flow through 1.5 to 2 ft.
contact to the volume of effluent applied. This promotes filtration and exposes the effluent to of sandy fill at loading rates of 5 cm/day will yield effluent which present no health hazard from
more cation exchange sites for adsorption to occur. Higher moisture tensions slow the rate of human enteric viruses.
effluent movement through the soil, resulting in longer residence times for the hostile
environment to work on the bacteria. Labotatory and field studies have demonstrated that flow
through 2 to 4 feet of aerobic unsaturated soil provides near complete bacterial pathogen
removal.
----- II - -- -t - -
NO,-N: The drinking water standards and maximum contaminant limits are divided into two separate
categories. Primary and secondary standards have been established because some of the
The primary treatment processes operating on nitrogen compounds within the soil are contaminants listed have been linked to health problems. N-N, synthetic organic compounds
mineralization, nitrificaion, and denitrification. Nitrogen entering the soil from septic tank and many metals fall Into this category.
effluent is primarily in the form of the ammonium ion and secondarily in the form of organic
compounds. Organic compounds are mineralized by microbes within the soil, resulting in the The secondary standards have been established for reasons of aesthetics, taste, or other
conversion of organic N to the ammonium Ion. Ammonium ions are positively charged and are non-health reasons. Iro and manganese cause taste and laundry staining problems for instance.
quickly attached to cation exchange sites within the soil. In unsaturated aerobic soil conditions
nitrifying bacteria oxidize the ammonium ion to nitrite and then to the nitrate ion N,-). a Bacteria - One colony per 100 milligrams water
NO-N Is a highly soluble negatively charged compound which is repelled from the cation
exchange sites within the soil and Is free to move with the percolating water to the water table. b. Synthec Organic Compounds - Although standards for common organic compounds
Several studies have indicated that there is a nearly complete conversion of the organic nitrogen vary, many of the current recommended limits are below 100 parts per billion in
and ammonium ion to NO-N within the first few inches of entering the aerobic treatment zone. drinking water, with some recommended limits as low as 5 parts per billion. This is
equivalent to one ounce In about 1.5 million gallons. The current drinking water
Once created, some of the NO:-N can be removed from the percolating effluent, provided soil standard for ben ene, a common constituent of gasoline is 5 parts per billion.
conditions are present which are conducive to the denitrification of the NOON. Denitrification
is a process in which NO,-N is reduced to gaseous nitrogen compounds by biochemical c. Nutrients - The current drining water standard for NON is 10 mg per liter. There
reduction. Two enzymes produced by facultative denitrifying bacteria under anaerobic is no drinking water standard for phosphorus.
conditions (i.e. dissimulatory nitrate reductase and dissimulatory nitrite reductase) are the
cataly which permit this process to occur. In order for denitrification to be a benefit in the d. Other Consttuents Drinking water standards for the other constituents are: Chlorides
treatment process, the percolating effluent must encounter an anaerobic (saturated) soil condition 250 mg pr liter Specific Conductance - no limit; Toxic metals varies but typically
which has a suitable carbon energy source for the denitrifying bacteria. These conditions are lower than . mg per lite
most likely to occur in soils that are saturated near the soil surface. One study, in fact, reported
very high rates of NO-N removal from ground water after flowing only a few feet through
wetland soils (poorly drained).
GROUNDWATER IMPACTS
Groundwater Is the first recipient of sewage effluent disposed of in properly constructed and
designed septic systems. Although the septic nkt/soil treatment system- is effective in
substatially reducing many of the contaminants associated with sewage effluent, the effluent
alters the natural background ground water quality in the vicinity of the septic tank leachfield
system.
Drinking Water Considerations:
Throughout history, poor drinking water quality has led to numerous disease outbreaks. As a
result, the medical profession has promulgated standards for drinking water quality, which offer
protection from waterborne disease. The current drinking water limiting standards for the
'problem constituents described above are as follows:
SURFACE WATER IMPACTS block sunlight penetration through increased turbidity levels These events result In adverse
impacts to habitat quality for fisheries and other aquatic plants u well as interfering with
recreational aCvides such Ds swimming and boating Phosphorous is typleally the limiting
Surface water resources of The U.S. Virgin Islands are comprised of two major categories, nutrient of codcern controlling aquatic plant growth In fresh water resources while nitrogen
inland or fresh water resources and coastal water resources. Both categories have been is the limiting nutrient of concern for coastal water resources.
recognized nationally as being vital resources beneficial to the economic and environmental
well being of the country. Past human activities associated with cultural encroachment on The presence of pathogens in surface water resources s of a concern with respect to health
these resources resulted in wide spread degradation of their quality through the discharges related issues Recreational activities such u swimming an be impacted from the dosing
of pollutants and loss through conversion for urban uses. In response to these activities of beaches due.to patbogen contamination. Uterature review conducted by otbers report
Congress enacted the Clean Water Act (CWA) to abate and control sources of water 58 incidences of shelfishb waters being closed or restricted In the Mid-Atlantidc ocean as a
pollution. The initial thrust of the CWA provided for the regulation of point sources of result of contamination from urban runoff and 11 incddences of dlosre resulting from
pollution through the National Pollutant Discharge Elimination System of section 402 of the pathogen contamination from septic systes.
act and the discharge of dredged and fill material through section 404. In 1987 Congress
amended the 'Declaration of Goals and Policy' section of the CWA to include nonpoint
sources of pollution and enacted section 319 to the CWA. establishing a national program
to control nonpoint sources of pollution through the adoption and implementation of
management programs. Additionally, in 1990 Congress enacted legislation (Coastal Zone
Act Reauthorization Amendments of 1990) which requires Coastal Zone Management
programs established under the Coastal Zone Management Act of 1972 as well as Nonpoint
Source programs established under section 319 of the CWA to address the impact of
nonpoint sources of pollution to coastal waters.
Discharge of domestic wastewater to the environment through the use of septic systenm has
been widely recognized as a source of nonpoint pollution which can affect surface water
quality. Pollutants of concern which have been shown to detrimentally impact water quality
are nutrients and pathogens, Nutrients are nitrogen and phosphorous compounds while
pathogens are disease causing micro-organisms that are present in the feces of infected
individuals. The presence, fate and contaminate transport mechanisms of these pollutants
within the subsurface environment is thoroughly discussed elsewhere in this document
Nutrients Introduced into the subsurface environment from septic systems are typically
delivered to surface water resources through groundwater discharge with the density of
septic systems adjacent to these resourcescontrolling the level of nutrients being delivered.
Some nutrients and pathogens, resulting from the surface discharge of failed septic systems
built in unsuitable soil conditions, can reach surface water resources through urban runoff.
Pathogens can also be delivered through groundwater discharge in areas where adjacent
septic systems are built to close to or in highly fractured bedrock formations that do not
have the ability to remove them prior to the waste stream reaching the groundwater table.
All plant growth requires nutrients as energy sources for metabolism. In surface water
environments low levels of nutrients from naturally occurring sources, typically less than 03
mg/I for nitrogen and 0.05 mg/l for phosphorous, are the Limiting factors controlling aquatic
plant growth. The presence of nutrients in concentrations above natural background levels
as a result of adjacent human encroachments have been shown to induce excessive aquatic
plant growth activity, resulting in a degradation of surface water quality through a process
termed as cultural eutrophication". The increased level of organic matter added to surface
water systems through this process can rapidly deplete the resources oxygen supply and
OTHER ALTERNATIVES FOR SEWAGE DISPOSAL EVAPOTRANSPIRATION
It is estimated that there are approximately 5,000 evapotranspiration units currently In the United
States. Evapotranspiration and evapotranspiration/seepage systems have been proposed as a
aea of suitable soils is not pesent, o whee limiting conditions simple solution to the widespread wastewater disposal and ground water contamination problems.
In areas in which an adequate area of suitable soils is not present, or where limiting condiuons
aoccur alternatis it disposal systems including surface discharge, evapotranspiration beds and Evapotranspiration systems utilize capillary action in shallow sand beds or trenches to draw
occur, alternative disposat systems, rincluding surface discharge, avapotranspiraon beds and liquid up towards the surface and the plant root zone where it is removed by evaporation or
utilized by vegetative transpiration. An evapotranspiration/seepage system uses the limited
FLTRATION infiltrative capacity of the soils surrounding an unlined evapotranspiradtion bed to provide soil
absorption to aid In the elimination of the applied liquid load,
Although the use of filtration followed by disinfection and surface discharge is not a Many factors affect the rate of evapotranspiration at a particular site including the available solar
recommended alternative for s ingle family homeowner operated on-site w astewater systems, it radiation, temperature, elevation, relative humidity, wind speed, soil moisture availability, plant
may present an alternative for small community and hotel developments which propose a single density and species dstibution, and bed surface area. Additional factors which need to be
density and species distribution, and bed surface area. Additional factor which need to be
wastewaer treatment system to be maintained and controlled by a competent operator. considered in the design and siting of an evapott ranspiration bed include the annual and seasonal
Single pan surface sand filters are relatively simple mechanical filtration systems which use temperature patterns and rainfall intensity and duration.
approximately 24 inches of sand to provide polishing to septic tank effluent intermittently loaded
to 2 of mom filetaion units. Evapotranspiradon beds are best suited for hot, semi-arid regions. The heavy rainfalls that are
to 2 or more fltsheion units. Theo e systems may present w hsom e odor problems sand require typical of the Virgin Islands climate makes evapotranspiration of limited use as a sole treatment
periodic Wldng of dhe surface to break-up the hard crust which develops. Buried sand filters method. While a conventional soil absorption system may actually involve some degree of
were developed as a lave in order to minimize the offensive odor oftentimes associated evapotranspiration in the removal of nutrient s and liquid wastes, this Impact is usually neglected
C with su flters. These units are typically designed with I to 3 gallon per day per square in the d esign of soil absorption systems.
foot loading rates intended to provide adequate detention times necessary to achieve maximum
! suspended solids removal. PEAT BED FILTRATION
AEROBIC LAGOONS
Peat moss has proven to be effective in the removal of trace materials (copper, nickel, cobalt,
Aerobic lagoons have beesn proposed for rural areas where conventional septic systems are not and zinc) and has been successfully used in the treatment of industrial wastes. Nineteen cities
possible. The design of aerobic lagoons is similar to that used for the stabilization ponds in Finland use peat bogs for municipal wastewater treatment and studies have been conducted
in Wisconsin regarding the use of peat bogs for the polishing of effluent from sewage lagoons
municipal oxindtion pond will typicall y use i detention time of approximately 30 days. and secondary treatment plants. Peatlands, peat trenches, and swamplands have been used as
Housichoid aobxid a goons, due to ty he i r much smaller size and increased chance of short a main form of wastewater treatment, following pretreatment in a septic tank and aerated
Household aerobic ilgoons, due to their much smaller size and increased chance of short
circuiting, are typically sized with a detention time of 100 days corresponding to a surface area
of appiotimately 220 square feet per person and a liquid depth of 3 feet. The minimum
recommended size of n aerobic lagoon is 900 square feet with improved operation anoted wh en Studies conducted in Maine on the construction and use of Sphagnum peat beds for wastewater
recommendnd size of an aerobic lagoon is 900 square feet, with improved operation noted when
a minimum size of 1,050 square feet is used. Anaerobic conditions may result in the bottom treatment reveals that these systems may indeed offer some benefits but will need increased study
sediments (facultative lagoons) with aerobic treatment layers only present on the surface. This to prove their worth and f found to be acceptable will require competent designe and
installers. Peat beds display a range of hydraulic conductivities, depending upon the degree of
may lead to increased odor problems, and therefore should be avoided or closely monitored.
humidification, water content, dry density, type of peat and depth of sample. The reported study
The effluent quality of an aerobic lagoon can be generally very good: especially in warm utilized a 75 cm (30 inch) deep peal bed and loading rate of 1.5 cm/d (0.35 gpd/sf. The results
climates where gtrter than 90 percent BOD reductions may be accomplished. The unit should of the study indicate fh at t he peat bed worked satisfactorily with no problems or odors and no
be preceded by a septic tank and should be located 150 to 200 feet downwind of the nearest visible ponding of efuenl.
residence, open to direct sunlight and wind. Berms and fences shdulO be constructed
surrounding the lagoon utilizing proper construction techniques including 3:1 sideslopes, a 4-foot
wide top and 2 feet of available freeboard.
DISCHARGE FROM PRIVATE SEWAGE TREATMENT PLANTS
ANAEROBIC FILTERS
Because of resons outlined elsewhere in this report, it appears that the use of package
Anaerobic filters have since been developed as a pretreatment device for domestic discharges treatment plants will be needed to treat sewage generated on the islands. The use of these
and for high strength or acidic industrial wastes, and are currently receiving increased attention plants then leads to the need for treatment and disposal of the outflow from them The
u an alternative treatment process designed to anaerobically treat and dentrify aerobic treatmcnt characteristics of this outflow Is shown in the following table:
unit effluent.
Anaerobic plug flow filters are chambers filled with a solid media which promotes fixed film
and interstitial microbial growth. These chambers are usually operated in an upflow mode and Septic System Effluent vs. Advanced Wastewater
can be as simple as a concrete septic tank or water-tight chamber filled with rock. Anaerobic Treatment Facility Effluent Chacteristics
plug flow filter systems provide many advantages to the use of aerobic filters, including the
removal of organics as gases like methane, carbon dioxide and nitrogen rather than fixed as new
cell material. This results in a decreased sludge volume which is 6-10 times as dense as an
aerobic sludge. Additional advantages include the ability of the system to handle shock loads, Influet Effluent Quality-
the ability of the system to survive for extended periods on no load at all, an improved effluent arame te uai1 WSWecT
quality transported to the soil absorption system, and low cost of operation and maintenance.
BOD5 300 170 IS
DISINFECTION
Suspended Solids 300 60 <10
Disinfection of wastewaters can be accomplished by a variety of chemical, physical. mechanical,
and radiation techniques designed to physically trap the bacteria cell or to inactivate the cell by Total Nitrogen (as N) 45 42 <10
mechanisms causing damage to the cell wall, alteration of the cell permeability, alteration of the
colloidal nature of the protoplasm or inhibition of the enzyme activity. Disinfection of Ammonia-Nltrogen (as N) 12 40 < 2
household wastewaters has been advocated in many states prior to surface discharge to water
bodies. Simple disinfection devices which have demonstrated some reliability in domestic use Nitrate-Nitrogen (as N) 0.6 0.04 <10
include ultraviolet radiation using mercury vapor lamps and dry feed chlorination systems.
Proper disinfection requires a clarified effluent as suspended solids, metals, and refractory Total Phosphorus (as P) 25 14 10
organics Interfere with the process. Because of this need for a highly purified effluent, sand
filters or some other system may be necessary prior to disinfection. Fecal Coliform 3x10 5x106 c 100
(coliform/100 ml)
SEWAGE TREATMENT FACILITIES
1. Measured prior to land application
The preceding sections evaluate non-conventional and modified treatment processes intended to 2. AN values in mg/l except as noted
provide an alternative to the conventional septic system. Many of the treatment options 3. Secondary and treatment followed by identicnauon and disinfection
discussed In the preceding paragraphs have processes which go beyond the scope of the simple
subsurface septic system and would approach being classified as sewage treatment facilities. REFERENCES: () Canter LW., andRobe C Knox SepticTankSyte Effets
Sewage treatment facilities have been used in the Virgin Islands .for many years to treat on Ground Water Quality Lewis ublishers. Inc Cbelse
wastewater flows from urban areas housing developments, hotels, and other projects. Michigan
Sewage treatment facilities generally include primary settling followed by aerobic treatmcnt, (2) Massachusetts Division of Water Pollution Control File Dat
secondary settling, filtration, and disinfection. Effluent disposal is usually accomplished through
ocean outfallirrigation or some form of surface disposal. (3) USEPA. Aterative for Sm all Wastewater Treatment Systems,
EPA-625/4-77-011, 1977.
- - - --- -- - - -- - -
During the disposal proess the effluent Is either discharged directly to surface waters or
ground waters. Depending on which type of discharge Is selected. thq method of treatment
will vary. Sewae treatment facilities generally Include primary settling followed by aerobic
treatment secondary settling, filtraton, and disnfection. Effluent disposal is usually TERRACE TERRACE
accomplished through ocean outfall, irrigation or some form of surface disposal. 2 ORIGINAL GROUND F RONT SLOPE
(SURFACE 12-8M TERRACE ORIGINAL GROUND
Sewagrereatment faulities have the potential to produce an effluent far superior to that SURFACE
produced by conventional septic tank systems. Aerobic biological treatment processes are --
capable of removing substantial amounts of DOD and 'SS over and above that removed in
the coavendonal ieptic tnk. More importnmtly, the proces is capable of nitrifying the CONVENTlONAL STEPUP
ammonia in the wastewater to nltratenltrogen, which then can be removed through a TERRACE TERRACE
denitrifiecation process. Disinfection is also typically employee at such facilities providing
signifleant reduction in the number of pathogenic organisms in the wastewater prior to its
release into the environment.
Surface Water Mlieharee:
Surface water discharge will normally be a direct discharge to the ocean. ponds, streams,
guts or other accumulations of waters This type of discharge is generally associated with
moderate to large waste water treatment facilities serving communities or government
operated. A permit under Chapter 7, Tide 12, Section 182 of the rules and regulations of ORIGINAL GROUND
the VI is needed for any surface water discharge. Tbis will normally require at least ORIGINAL GROUND TERRACE SURFACE 1>8%1
SURFACE < :%: BACK SLOPE
secondary treatment of the discharge and under some circumstances additional treatmenl TERRACE SOPRRACE
Ground Water Discharee:
Ground water discharge is accomplished by several methods to include seepage pits, leach
fields, wetlands, land application and others. In these methods, effluent is applied to the soil
and a combination of natural physical chemical and biological processes within the plant- BACXKTO.-ACK STEP-DOOWN
soil .water matrix. provide the desired treatment. Again, because of conditions unique to TERRACE
the Virgin Islands. only one system of land application appears to be practical. This system
is called the overland flow system.
Overand Flow Svstem:
The overland flow system functions when effluent is'applied to the upper portions of sloping,
grass covered fields and allowing it to Dlow over the vegetated surface. These grass covered
fields are normally called terraces. At the bottom of the slope a series of collection ditches
are used to collect the treated effluent which can be reused or discharged to surface waters.
This proces is prticularly suited to solls with very flow permeability, in that it is not
dependent on infiltration and the treated effluent is discharged as a point source.
The principle objectives of this system are to achieve secondary effluAnt quality when TYPES OF OVERLAND FLOW TERRACES
applying screened raw wastewater and high levels of nitrogen BOD, and SS removals.
fal r aft AN
CURRENT PRAMrCES
Several areas 10 concern have developed through the preparation of thi report In which
IMF ILD, RUXDFI septic system practices being used In the U.S. Virgin Tslands are In direct conflict with the
L LI Cf ION present understanding of their design. construction, operation and the resultant effect
Lbereof on public heajth issues and environmentatl quality. Some of thuse concerns may
have simple solutions solvable through rule changes whie others wil require difficult
SLOPE 1.11 decisions regarding restrictions on the use of septic systems in certain aureas
Design requirements for septic systems appear to be modeled after U.S. Public Health
PtiC@ t Ilk Service recommendations of 1960's vintage and have not been reviewed since the 1970's
They do not provide for the adequate sizing of system components, adequate assessment of
(3) HIYDRAULIC PA THWA Y the suitability of a site for septic system placement, or adequate separation distances from
physical constraints (see Log Sim); considerations which can lead to prematu re failure and
public health risk from inadequately treated wastewter carrying pathogens being discharged
to the surface (we Site Assessment) or into bedrock aquifers (see Groundwater Quality
Protection).
bt PI CTOR IAL Y IA OfI SPAI XKLE AP FL IC A TI 0x
OVERLAND FLOW
D. Septic Tanks
EXISTING REGULATIONS
The size of septic tanks is based on the number of bedrooms, the minimum tank size
SEPTIC SYSTEMS being 500 gallons for a two bedroom home. The dimensions and construction must
met the following standards:
New septic systems are regulated u pan of the Environmental Laws and Regulations of the
Vllian Islands. Title 19, 1979. This publication describes how septic systems shall be (1) Tank shall be watertight construction, made of sound and durable materials,
designed and constructed along with percolation test criteria and dimensional criteria. A not subject to excessive corrosion or decay.
synopsis of the regulations are as follows:
(2) Tank shall be a minimum of 33 inches wide, with a liquid depth between 4
A. Location of Sewape Svstems and 6 1/2 feet.
Location and Installation of the sewage disposal system shall be such that, with (3) The Inlet and outlet of each tank or compartment shall be baffled to provide
reasonable maintenance, it will function in a sanitary manner and will not create a a storage volume for scum.
nuisance nor endangle the safety of any domestic water supply. In determining a
suitable location for the system, consideration shall be given to the size and shape (4) Access manholes shall be provided over the inlet and outlet of the tank.
of the lot, slope of natural and finished grade, depth of ground water, proximity to
existing or future water supplies, and possible expansion of the system. E. Subsurface Disoosal Field
(1) No part of the system shall be located so that surface drainage from its (1) At least two percolation tests are required at different locations on the
location may reach any domestic water supply: disposal field according to a prescribed method. Where fissured rock
formations are encountered, tests shall be made under the direction and
(2) The lot size shall be sufficient to permit proper location, installation, and supervision of the Department of Health.
operation.
(2) The total bottom area of the disposal field trenches shall be based on the: (a)
B. Sentle svstems or alternative vwtems are allowed. If a 'septie tank system' is percolation rate of the soil and, (b) number of bedrooms In the dwelling. The
employed, it must consist of a septic tank, subsurface-disposal field, or seepage pits. minimum trench bottom area per dwelling unit shall be 150 square feet.
or combination of the two.
(3) Soils with a percolation rate over 60 minutes per inch are unsuitable except
C. Minimum Distances (in feet) required between septic system components and the for special design with seepage pits.
following items:
Subsurface (4) There shall be a minimum of two (2) disposal trenches per field and trenches
Septic Disposal So.p shall be:
Tank Field EL. .
(a) 8I to 36' Wide.
Property Line 5 10 10 (b) 18' to 36' Deep.
Any Domestic Water Supply 50 50' 100 (c) Between 6 and 9 feet minimum spacing, center to center of trench,
Dwellings 5 10" 20 depending on trench width.
Streams ..... 25
Large Trees --..... 10 ----- (5) Pipe for trenches shall be a minimum of 4 inches in diameter and shall be
perforated or laid with open joints.
Seepage Pit .---- 6' 3 x dia.
* Shall be increaed pet Dept. of Iletilh recommeolnow w.here r lsttlng wea , are enr. untred.
May be rtduacd to 5/feet where proper d'rnl.nge coldiow er tst.
compared to that of another can vary considerably, it Is typically no greate than 60 ped
(6) Trench ill material shall be crushed stone. gravel, slag, clean under or similar and seldom exceeds 75 pcd. Maximum daily flows on the other hand, are estimated by
material acceptable to the Department of Health. Fill shall extend a multiplying a safety factor to increase the average flow rate. The general pracdce in the
minimum of 6 inches below pipe and 2 inches over pipe. continental United States is to use a value of 75 gallons per person per day for sewage
disposal design.
(7) Trenches may be terraced to maintain proper grade and cover.
In the Virgin Islands, the amount of wastewater now is dependent upon and related to the
F. Se apPitU availability and perceived cost of the water supply. During the wet seson, when a
household's cistern is near overflowing and more rain is expected, the water use may Jump
(I) Use of seepage pits with septic tanks is acceptable only when such use is to 80 or 90 gal/capita/day. But, during a drought, when the cstern Is almost empty and a
necessary because of soil conditions or topography and when such use is load of a trucked in water is necessary, extreme water conservation methods re usually
satisfactory to the Department of Health. Seepage pits shall not be used in employed. The water consumption may drop to 20 to 30 ga/calpta/day.
limestone areas or in localities where shallow wells are used as a source of
water supply.l The Virgin Islands Environmental Laws and Regulations do not specify a per aplta design
value for wastewater flows to disposal systems. Instead, disposal fields ae designed by
(2) The size of the seepage pits shall be based on the: (a) character of the soil correlating the trench seepage ea with a peroladon rate and the number ofbedroms
(i.e., sand, gravel, or sandy/gravelly clay), and (b) the number of bedrooms served by the system. Comparng the regulation's absorption ara values with milr dat
in the dwelling. published by EPA, it can be inferred that the current regulations are assuming a wastewater
flow of approximately 40 to 5O gallons per person per day.
F__4 (3) Seepage pits are unsuitable in "heavy tight clays, hard pan, rock, or other
< impervious formation'.
3o (4) Seepage pits shall be lined with brick, stone, block, or similar materials at
least four inches thick laid in cement mortar above the inlet, and dray with
two-to-four-inch open vertical joints below the inlet.
G. Distribution Box
A distribution box shall be constructed at the head of each disposal field for the
purpose of adequately distributing' flows between disposal trenches and/or seepage
pits,
WASTEWATER FLOWS
On-site wastewater disposal facilities are designed on the basis of the estimated volume of
wastewater flows. Sanitary wastewater is defined as wastewater discharged from plumbing
fixtures into the private disposal systems that the system will experience. EPA estimates
tuht the overall average daily wastewater flow from a. typical residential dwelling is
approximately 45 gal/capita/day. While the average daily nflow experienced at one residence
- ---- -- - ---
LOT SIZE AND SETBACK DIMENSIONS SEPTIC SYSTEM FAIURE
In the continental United States, sepdtic system failure is generally considered to have
Current land development codes allow lots with on-site septic systemsto be as small as one occurred when the soil absorption system either fails to accept wastewater or fails to
quarter are in site. his practice presents two are" of concern. The drst relates to the occurred when the sell absorption system either fais t o accept wastewater or falls to
quarter acre in size. This practice presents two areas of conceron The irnt relates to the adequately treat the wastewater prior to discharge to the ground water.
high density of development allowed on septic systems and the resultant impacts to
groundwater quality. The second concern relates to the lack of sufficient land area to meet In the Virgin Islands, many regulators consider failure of a septic system to occur only when
the spaiail requitreent oaf th e ondstneon of a housee c istern and septic system whi e there are complaints about sewage spilling over to abutters property or when strong odors
maintaining appropriate separation distances especially on sloping sites. Setback distances are enough to cause eighbon to complain
refer to the horzontal or lateral distance between the various components of the septic
tank/soil absorption system and areas or items of concern. For the most part, these include The Health Depanments on St Croix and S Thomas have indicated between 300 and 400
points of possible human contact such as cistens or dwellgs Generally, the speclfied septic system failures are reported on each island every year. Although failures s to be
separation distances are intended to provide dequte transport time for the passage of expected these fgures appear to be high with respect to the populaton of the islands which
effluent through the soil where the concentrations of contaminants are expected to be utilize septic systems and the likelihood that a significant percentage of failures are not
reduced by filtration straining. physical-chemical processes biological activity, dilution and reported. Public health officials attributed the high premature failure rates to the fact that:
dispersion. (1) construction in soils with low permeabillties; (2) Improper construction; (3) small lot
sizes on sloping sites; (4) the fact that there are no requirements In place for septic system
Title 19 Regulations currently require that in siting septic tanks disposal fields, and seepage upgrades when the use of n existing strueure is expanded; and (5) inadequate design
pits certain minimum horizontal separation distances be maintained with respect to: water requirement for septic system components. Seepage pits that re discharging waste water
supply, property lines; and dwellings while the regulations specify that the ten foot
separadtion be maintained between property line and disposal fields, no consideration is givenaaaa
to the fact that there may be a large difference in elevation between the septic system and Given the information acquired during the development of this report, it is estimated that
the abutting property. It is not uncommon to find a disposal field placed a short distancer than currently reaized The
away from the top of a one story reining wall or a very steep slope and the septic system predominant case of these filures is improper siing. Septic systems cannot operate
leaching out at the toe onto the abutting property. properly in impermeable soils nor bedrock. Once a septic system is located in an area that
does not have suitable soils and that system goes into failure, the only reasonable way to
BUILDING ADDITIONS reduce the impact of the failure is to:
The Department of Planning and Natural Resources Permit Division reviews new septic (a) provide holding tank capacity in which to store sanitary waste until the sewage
system design through the Earth Change' permit application process. During this process. can be removed by a septage hauler for disposal at a treatment facility. Due
the Department reviews the septic tank details drainage trench or seepage pit locations. site to the high cost this option is usually only a short term solution.
padint numbr of bedrooms. etc. Based on the apptoved plans the building and septic
system are built and an occupancy permit is issued. (b) limit the amount of wastewater discharged by employing water conservation
techniques. Wash clothes at laundromats.
It appeaun that once a building is constructed any funher building additions or alterations
does not necesarly involve the Earth Clinge Permit process and therefore does not (c) Connect to public or private sewer.
necessitate a review of the eisting septic system to ensure that its size will accommodate
additional bedrooms or other increases in occupancy.
INSPEC"IONS
Once septic plans are approved during the Earth Change Pcermit Process it has been noted
that many times the systems are not located as shown on the plans. Although there are
many opportunities for inspection by DPNR representatives it has 1hen noted that
inspections are either not as rigorous as one might expect, or the inspections are not
undertaken.
POLLUTION OF GROUNDWATER transmitting them. This results in a flushing action with rapid migration of contaminants
present to the groundwater.
Septic systems are very efficient in removing nearly all of the contnminants present in
domestic waste water when they are properly sited, designed and constructed. Use of septic Alternative nnutral systems which have been used elsewhere to overcome conditions of
systems in areas that have sold conditions which aue capable of accepting and transmitting shallow soils over bedrock formations primarily consist mound systems. SoD materials
septic tank effluent through several feet of soil under unsaturated flow conditions is capable of providing suitable treatment capabllitie, usually medium to coarse tenxtured
compatible with protecting groundwater quality for drinking water supplies as long as the sands, are Imported to the site to create the necessay separatidon distanac between a
density if installations is controlled to maintain groundwater nitrate-nitrogen levels below disposal fi6eld or trench system and the bedrock formation. In order to control etosion
10 mg/l. Use of septic systems which are improperly sited and constructed as well as in problems, construction of these systems are typically restricted to slopes of 25% or less.
areas with unsuitable soil conditions have been shown to discharge pathogens to These systems are not practical solutions in the U.S. Virgin Islands for the following reasons:
groundwater aquifers and have caused numerous disease outbreaks. The density of septic
systems has been shown to have a direct relationship with the level of nitrate-nitrogen in the * Construction materials necessary to build such a system are not readily
underlying groundwater table. Although no known studies have been conducted to date to available. Sand must be imported to the Isdlads and, where available, is very
specifically determine the fate of contaminants introduced into the environment through expensive.
current practices on the U.S. Virgin Islands. the routine presence of fecal bacteria and
elevated nitrate levels reported In the existing studies of the Islands aquifers clearly indicates Slopes of building sites typically exceed 25%.
a neu certainty that existing septic system practices have already impacted groundwater
quality. The spatial requirements necessary to build such a system are not provided
in the current minimum lot size standards.
PATHOGEN CONTAMINATION:
The cost of constructing such a system is estimated to exceed S35,000 for new
Current septic system practice in the U.S. Virgin Islands which is a primary concern with construction with the cost of retrofit to an existing developed site being much
respect to potential pathogen contamination of groundwater Is the construction of seepage higher.
pits or dry wells in areas with shallow soil depths over highly fractured volcanic bedrock or
limestone formationr These areas comprise nearly all of the existing and/or potential Pathogens are microscopic disease causing organisms that are indigenous to human and
building sites on St Thomas and St. John and cover a large percentage of those on St. animal digestive racts. They consist of certain bacteria, viruses and protozoa that are
Croix. As these sites are also located on steeply sloping landformns, the typical homesite is present in extremely high numbers in individuals who are either Infected or are carriers of
created by excavating extensive cuts into the landform and spreading the excavated rubble the disease and are shed through the feces of these individuals The prinary objective of
to create a level area to construct the home and septic system Any natural soil materials septic system design and construcion is to provide the treatment mechaisms necessary to
present on the site are removed or destroyed in this process. Depending on its location on effectively remove these organisms from the waste water stream before It reaches an
the site, the seepage pit used for final disposal of the septic tank effluent is constructed underlying aquifer formation. Pathogens which are allowed to reach such formations pose
either directly into the bedrock formation or the rubble derived from that formation used a threat to individuals or populations who rely on them for potable drinldng water sourcttes.
to create the building site.
A literature review conducted by Marylynn Yates and presented in Septie Tank Density and
This practice allows a direct connection for the septic tank effluent to pass directly into the Ground-Water Conltaination (Vol. 23, No. S-OROUND WATER-September-October
bedrock aquifers without the benefit of unsaturated flow through a sufficient soil medium 1985) reports that The consumption of untreated or Inadequately treated groundwater was
to effect pathogen removal. While plant uptake by root masses located within the fracture responsible for over one half of ad the waterborne outbreaks and 45% of all cases of
systems close to the ground surface may account for some removal of the septic tank waterborne disese In the Unites States from 1971 to 1979. (Disease) causing agent were
effluent it is unlikely that they are capable of removing the entire waste stream and determined In 45% of the outbreaks. Only 11%9 were caused by toxie chemicals; the vast
saturated flow within the fracture system can result in pathogen movement into the majority were caused by pathogenic (disease-causing) microorganisms. Tbe remainderwere
underlying groundwater within the aquifer. This is especially true during periods of heavy classified as acute gastrointestinal illnesses of unknown (caue). It is believed that many of
rainfall events which are the primary source of recharge to the aquifers. Water levels in these were caused by viruses such s the Norwalk virus or rotoviruses, for which detection
bedrock wells have been noted to have wide fluctuations during these events as recharge methods have only,recently become available. Overflow or seepage of sewage from septic
waters enter the aquifer at a rate greater than the cracks and fissures are capable of tanks or cesspools was responsible for 43% of the outbreaks and 639b of the cases of illness
caused by the use of untreated. contaminated ground water. Thus, septic tanks represent
-- -- - ----m------ --
a significant threat not only to preserving the potability of ground water, but also to human a 32 day sampling schedule and with he wet and cool soil it is highly robable
health.' a 32 day samplang .nschedule, d with the wet andc conoloions, highly probable
that their survival would extend considerably beyond 32 days.'
Removal of pathogens from septic ank effluent by soil mediums has been widely studied Keswiclk and Gerba conducted a literature review of the then available information on virus
and shown to be effective when the effluent Is able to flow though I sufficient depth of contamination of groundwater and reported their tindine in Viruses In groundwater
aerobic soil under unsaturated flow conditions. The treatment mechanisms involved in this (Environmental Science Technology, Vol. 14, 1980). Although little was known about
process are discussed in detail in Part 1 of thi report. Simply stated. pathogens are vimrs removal and tramnsport mechanisms at the time, one field study showed virus survival
removed from the waste stream through filtration and adsorption by soil particles. High for at least 28 days n groundwater and laboratory experiments showed virus survival in
moisture tendions present within the soil under unsaturated flow conditions retain the excess of 200 days in rinkingwater. They suggest that 'Since the effects of sunlight is
pathogens within the sola profle long enough for them to rendered Inactive through natural eliminated and the temperature is lower, even longer survival times would be probable in
die off due to bhostile environmental condtions o microbial utilization by other soil grounater". In 1982 IMeick. Gcrba etal published the results ofa study tited
organisms S depth t e, moitue cntent d tmpe ue e cricl charterisic of Ent Vis and ndaor Bacteria in GSofundwater. (J. Environ. Health, A17r "actesics
in determining the effectiveness of these proe Insufficient soll depth coarse textured of nric Vir w found that uan enteric viruses sun rndwat ive longer tha n 24 days in
medium saturted flow conditions and low soiln temperatures can individually or jointly groundwater (length of study).
minimize or obviate patbogen removal from a waste stream underneath a septic system.
The Robert S. Kerr Environmental Research Lab in Environmental Effects of Septic Tank NI ATE CONTAMINATION
Systems (US. Deparutmi of Commerce -Ntionai Technical Information Setvice, PB-272 Second in concern t o bacterial and viral contamination from septic systems is the movement
702, Aug 77) reports "Whether or not pollutants moving from the tile fields through the soil of nitrate-nitrogen into the groundwater Excessive amounts of nitrate nitrogen n drinking
reach the ground water and subsequently a water supply depends to a large extent on the water can lead to methemoglobinemi a condition which prevents the normal uptake of
type of subsurface material Involved and the thickness. Figure 6 presents four coimmon oxygen in blood of young Infants. In order to reduce its risk the Environment Protection
aquifer types which may transmit pollutatu s gret distans. Conventional septic tank Agency has established a maximum contaminate level of 10 mg/ for nitrate-trogen in
systems should be avoided n area where factured or cavernous formations, such as the public drinking water suppli In addition nitrate-nitrogen has been implicated in the
bottom three rock types, are less th an a few feet below the bottom of the absorption trench. formation of carcinogen In the digestive system (Cogger, On-alte Septic Systems:'The risk
Such rock types provide a minimum of the three major processes necessary to retard or of groundwaer contamination Journal of Environmental Health Vol. 51, No. ,
control the movements of pollutants-ltratbon, adsorption and microbial degradation. September/October 1988).
Generally, the issures and channels are too large to provide significant filtration. The
detention time and active surface areas available are not greit enough for appreciable Cogger, Kerr, Yates and others report numerous references in which septic system practices
adsorption or microbi al degradation to occur. It is important to note that volcanic rock have resulted in local and regional ntrate-nitrogen contamination of oundwater suppes.
(the most prevalent rock type in the US. Virgin Islands) comprises aquifer type 4 in the Long Island Cape Cod and the Delaware coastal plain are the most notable areas which
reference figure and carbonate rock (the Kingshill Formation on St. Croix) comprises
have received extenshve study. These studies demonstrate that nitrate can reach
aquifer type . unacceptable levels In groundwater beneath soils that are otherwise suitable for treating
septic tank effluent (Cogger). Kerr states that The most important parameter influencing
Once allowed to enter saturated aquifer, pathogens have been shown to survive and regional contaminatlon from septic tank systems is the density of these facilties in a given
remain active for a tended periods of time. In Survival and Movement of Fen Indicator area, although geology, depth to water table, and climate may effect the nature and degree
Baceri In Sod under Condiltons of Saturated Flow .(Journal of Environmental Quality, of the problem
Vol.7,no.l, 1P78) Hagedorn etal. studied the movement and survival rates of Srreprococc of the problem
faea/l/ and E t/atcoJa under saturated soil conditions Inoculations of both bacteria
re i andud i c under s aturated soil conditio ns noculationsnd the re of movemnt and survival vcteriae Nitrate-nitrogen is the end product of microbial mineralization of nitrogen rich organic
were introduced into saturated soil conditions and the rate of movement and survival were products as wastewater passes through an aerobic biologically active soil formation (see
monitored through sampling wells place various distances from the inoculation point. They discussion in Part 1). This process occurs in the soil treatment zone underneath a
report th ee concept s of major importance can be derived from tmhe.daa on the presence functioning septic system as well as in upper soil horizons at wastewater land application
of the indicator bacteria in the test wells. First, the bacteria moved long distances in a sies and results in a nearly complete conversion of organic nitrogen to nitrate-nitrogen.
relatively short period of time in a soil with a surface gradient of only 2%. Second. the Once formed nitrate-nitrogen is a very stable soluble compound that is not affected by
populations of indicator bacteria in the various wells reached maxima O uring intervals normal soil treatment mechanisms and readily migrates into the underlying water table.
closely asociated with the rise of the water table following major rainfall periods. Third. Mechanisms which are capable of reducing nitrate-nitrogen concentrations in a waste stream
both E. col and S. faecalis survived in appreciable numbers in the saturated soil throughout include plant uptake, mi crobial denitrification. and dilution. Nitrate-nitrogen is a fertilizer
and can be readily used by plants. Plant uptake can account for nitrate-nitrogen reduction
at land application sites where nitrate formation occurs close enough to the ground surface POL.LUTION OF SURFACE WATER
to allow contact with plant root masses. Plant uptake, however, is not likely to have an ,
appreciable affect in reducing nitrate-nitrogen concentration underneath a functioning septic Fresh water resources of the U.S. Virgin Islands are ephemeral in nature. Due to the
system (Cogger). Microbial denitrification can result in reductions when nitrate-nitrogen Islands climate and hydrogeology, groundwater tables rarely intersect and discharge to
passes into an anaerobic soil condition which has a suitable carbon energy source to allow the ground surface with the primary exception being in areas adjacent to coastal
the denitrificadon process to occur. This process typically happens in soils with high embayments. Fresh water resources consist of intermittent stream channel locally
groundwater tables and is not a significant factor in soils with no or very deep water tables nown as guts, and surface impoundments. Tese featurttes provide important functions
as are typically found in the U.S. Virgin Islands. Dilution with groundwater is the most by collecting, storing and transmitting surface water runoff from major storm events,
commonly used approach to control nitrate-nitrogen concentrations. This method requires Runoff which is able to be stored in the guts and impoundments are Important water
controlling the density of septic systems within a given area to levels at which the sources for irrigation/ agricultural uses as well as a major source of groundwater
groundwater recharge within the area is capable of diluting the nitrate-nitrogen recharge to underlying aquifers. Excess runoff which is discharged to coastal
concentratons generated by the septic systems to concentration below 10 mg/I. When embaymnents supports their unique ecosystems. As these resources serve as groundwater
density of development becomes too high, dilution no longer is an effective means to control recharge sources and are generally not receptors for groundwater discharge, the
nitrate-nitrogen concentrations (Cogger). operation of septic systems within their catchment areas through practices that do not
result in surface discharge of inadequately treated waste water is not Ukely to cause
One typical approach used to control septic system density is through minimum lot size threats of nopoint source pollution. Operation of septic systems through practices
requirements designed to insure that the yearly volume of rainwater infiltration which occurs which result-in high densities of failures, however, is a concern with respect to nonpoint
on the lot is sufficient to dilute the nitrates generated by the septic system to 10 mg/l or source pollution. Pathogens and nutrients present through the surface discharge of
less. Several mathematical models have been developed to estimate the land area necessary inadequately treated waste water are readily incorporated within the runoff generated by
to accomplish this approach and/or to estimate an appropriate density of development heavy storm events and are flush into surface water systems. While this may not pose
within a given area. One such model, A Procedure To Determine Ontimum Densirv For long therm threats to the guts lad impoundment areas which are ephemeral and dry
Homes Jsin Individual Wastewater Treatment Svstems Based On Nitroaen In Ground most of the time, impoundments which have the ability store water on a more
Watier. Rehag was developed by the consulting firm of Geraghty & Miller, Inc and others permanent basis and the coastal water resources which are receptors of pollutant laden
through the National Association of Home Builders-National Research Center. This runoff are at risk. The areas of particular concern with respect to this issue are densely
method has been applied to some areas in the northeast and has resulted in minimum lot developed areas in the alluvial and deep volcanic parent materials with montmorlllonite
size requirements of between 3/4 and 2 acres depending on soil/slope conditions present clay mineralogy on the Island of St Croix. These areas have large catchment areas and
on the lot. Climatic conditions in the U.S. Virgin Islands, however, are considerably are reported to have the highest incident of septic system failures.
different than in the northeast. Although average annual rainfall is similar, the amount of
recharge to the water table is drastically less, estimates by the U.S. Geological Society result As previously stated, Montmorillonite clays exhibit a very high shrink/swell capacity and
in about 1.5 inches per year, Applying this information through the referenced model can absorb water at a rate of twenty to thirty times their own weight, Percolation tests
results in lot size requirements for the U.S.'Virgin Islands of approximately 7.25 acres per conducted as part of this study in one such soil, Hogensborg. clearly demonstrated that a
home in order to control nitrate-nitrogen contamination (figure GWI). Inputs to the model conventional percolation test could greatly over estimate these soils ability to accept and
to arrive at this figure assume an average occupancy rate of four individuals per home using transmit septic tank effluent. The Hogensborg accepted water at a uniform rate of 10
55 gallons of water per day and generating 9 pounds of nitrogen per year each (nationally rnin/in for several hours and would appear to have stabilized, meeting the criteria for a
recognized standards). In addition the average annual recharge rate of one inch per year conventional test. In fact this soil continued to accept water 16 hours before enough
is assumed to occur uniformly over the landscape and the nitrate-nitrogen concentration in water had been applied to satisfy the montmorillonite clays absorption capacity, at which
the homes drinking water supply Is 0 mg/I. While refinements to these assumptions would point the swelling of the clays closed reduced the flow paths available for water
need to be made in order to implement minimum lot size requirements in the U.S. Virgin movement to such an extent that no measurable Infiltration was occurring thereafter.
Islands for the purposes of controlling nitrate contamination, it is obvious that the land area The continuous application of septic tank effluent to these soils will have the same
required per lot would not be realistically implementable.' · effect, resulting in failure and surface discharge. Continuing to allow the construction of
septic systems in these areas will Increase the nonpoint pollution threat from surface
water runoff generated in these areas.
Coastal water are the most abundant and valuable surface water resources of the U.S.
Virgin Islands, They consist of beaches, salt marshes, salt ponds, mangrove swamps,
- m - --- I --- -' t -
coastal embayments and shallow reefs distributed all along the Islands shorelines. Many Islands has established low density and moderate density zoning districts adjacent to
of these resources have unique environments that rely on fresh water sources supplied by many of the Islands Sensitive Coastal resources, it is unlikely that they will be able to
groundwater and surface water discharges as well as their adjacent marine environments. appreciably reduce the threat of nitrogen impacts to these resources from septic systems
As nitrogen is the limiting nutrient controlling excessive aquatic plant growth in these given the minimal amount of rainwater infiltration available on the Islands for dilution.
environments, the concentration of nitrogen compounds in the fresh water resources The same is true when considering the use of denitrification systems as alternatives.
discharging to these environments is a primarny concern of management programs to
abate and control nonpoint source pollution. In 1986 the U.S. Geological Service
reported that the median nitrate-nitrogen concentation of groundwater samples
collected from coastal embayment aquifers 0.2 mg/l Although this is within the range
considered to be naturally occurring the higher levels of nitrate-nitrogen reported in the
groundwater clearly indicates that coastal resources whose catchment areas are currently
developed or are slated to be developed with densely placed septic systems are at risk.
This s further demonstrated by the 4.9 mL/I of nitrate-nitrogen concentration reported
in a sample collected from the coastal embayment aquifer adjacent to Cruz Bay on St.
John in 1984 by the U.S.G.S..
'Guidance Specifying Management Measures for Sources of Nonpoint Pollution in
Coastal Water (EPA-80-3-92-002 January 1993) issued by the Environmental Protection
Agency recognies the threat of nitrogen contamination to coastal waters from septic
system practices and offers general management recommendations to reduce this threat
from septic system practices for new systems as well is from existing operating systems.
Recommendations for new systems that are important considerations in protecting the
U.S. Virgin Islands coastal resources include the following:
Insure that new On-site Disposal Systems (OSDS) are located, designed, installed.
operated, Inspected and maintained to prevent the discharge of pollutants to the
surface of the groud nd and to the extent practicable reduce the discharge of pollutants
into groundwaters that are closely hydrologically connected to surface water.
* Direct placement of OSDS away from unsuitable areas and to ensure that they are
designed or sited at a density so as not to adversely affect surface water or
groundwater. Unsuitable areas include are*s overlying fractured rock that drains
directly to groundwater.. Establish protective setbacks
· Where conditions indicate the nitrogen limited surface waters may be adversely
affected be excess nitrogen loading from groundwater. require the installation of
OSDS that reduce total nitrogen loadings by SO, percent..
Recommendations for managing existing operating systems include inspection programs
to insure proper operation and maintenance as well a replacement and/or retrofit of
OSDS components that reduce total nitrogen loading.
All of the discussions and arguments presented in the sections on pollution of
groundwater by pathogens and nitrates as the result of current septic system practices in
the U.S. Virgin Islands are equally applicable to the issue of nonpoint soutce pollution to
coastal witers. Although the Coastal Zone Management program of the U.S. Virgin
PERCOLATION TESTS RECOMMENDATIONS
The Environmental Laws and Regulations of the Virgin Island Title 19, requires that
percolation tests be performed in at least two different locations on the disposal field.
RECOMlENDATION #1
The percolation test, often simply called the perc test, is a measure of a soil's ability to
drain or "percolate' water into and through the soil. The basic method of conducung the Begin the process of ending the construction of septic systems that discharge septi tank
percolation test is to dig or auger a hole in the soil 6 to 12 inches in diameter to the fluent into the ground This can be acompllsbed by enforcing the exiing USV1.
depth of the proposed soil absorption system. Water is poured into the hole to a depth regulations as they re now wntten.
greater than 12 inches and allowed to drain This procedure is repeated until the rate at
which the water level drops is more or less constanL The hole is then refilled to a depth 25X5=
greater than 12 inches and the amount of time it takes for the water level to drop one
inch is determined. The percolation rate, reported in minutes per inch. is used as a The original intent of this study was to find ways to improve upon the existing septic
determination of the suitability of the soil for absorbing septic tank effluent and for system regulations to bring them into compliance with te usual stndards for design and
determining the size of the leaching structure. construction of on-site disposal of sewage effluent. The strategy In performing this study
was to assume that subsurface soil absorption (disposal trenches, beds, seepage pits) Is
The clay soils in the Virgin Islands make percolation tests very difficult to perform. The the preferred on-site disposal option because of its relability with a minimal amount of
clays are typically so dry and well.structured that initial percolation rates are in the range maintenance. he process wa then to analyze the soils topography, geology, and other
of porous sands and gravels (less than 10 minutes per inch). Other contributing factors characteristics of the Islands so that the regulations could be customied to ft the
to the quick pere rates are worm/insect larvae holes, roots, and the shalow depth to specific circumstances. In those reas where the site baracteristica re untable for
fractured bedrock. Only after constant refilling of the hole will there be a gradual soil absorption systems, alternative methods would be Ivestigated a last resort for on-
swelling of the clay particles and a decelerating perc rate. There are sois such as site disposal since these alternatives are typically the most costly to construct and require
Hogensborg on SL Croix, that after hours of soaking will become so impermeable there a great deal more maintenance and supervision than soil absorption systems.
is no measurable drop in the hole.
Now that the analysis of the Islands characteristics is completed, it has been found that
The small size of the disposal fields that have been constructed in areas of clay sois the vast majority of the Islands land areas ae unsuitable for soil absorption systems. It
indicate that one of the following is occurring: has also been found that thousands of the septic systems currently in operation are
located in the areas that are Inappropriate for subsurface disposal and represent not only
a) Percolations are being performed in a way that does not allow the clay particles to a ha-ard to the environnent but more importantly, a risk to the public's health.
swell, therefore, do not approx/mate wet soil conditions, or
swell, therefore, do not approximate wet soil conditions, or The U.S.V.I. Tide 19 Regulations contain some very important passages that, if
b) Percolation tests are not being performed t all and the pere rates and disposal field interpreted properly, can be used as a means to bring about the necessary change in
sizes are based on past practice. regulating septic system construction. These paragraphs are discussed as follows:
Seepage Pis:
Title 19: 1404-92. SeenaPe Pitt Use and Location:
'Use of seepage pits with septic tanks Is acceptable only when use Is necessary
because of soil conditions or topography and when such use is satisfactory to the
Department of Health.'
This particular regulation is the caveat that allows developers to construct septic systems
on the Island's steep hillsides, where shallow clay soils are underlain by fractured
bedrock. It has been demonstrated (refer to section on Ground Water Quality) that the
channels and fissures in fractured rock do not provide the filtration and absorption
---rn-rn------ ------
required to treat sewage before it reaches the groundwater. DPNR and the Department RE JMMENDATION #2
of Health can essentially bring this practice to an end by simply recognizing this hazard
and mandating that it is no longer acceptable. Extend the municipal sewage collection system and treatment plant capacity to all
Once the option of seepage pits is unavailable, there re no reasonable alternative soil populated are
absorption systems that can be reasonably constructed on all hilsides due to the steep Discussion:
slope, small lot sizes, and cost constraints.
Realistically, if a non-rural community does not have the soils geology, or other
EP rclation : characteristics that allow the use of low-cost, soil absorption septic systems, the best
proven alternative is td create or expand municipal sewers and treatment plants. The
Title 19- 1404-92. Percolation Tests- Pararanh 4: Public Sewer System Is particularly well-suited for the Virgin Islands for the following
reasons:
'(4) ... Because many seasonal factors affect the results of percolation tests,
judgement is required in nalyzng these resultl If the tests are not conduced a) Much of SL Croix and most of St. Thomas is densely populated and new
during a wet season they should be repeated until the moisture conditions of the soil developmen t c ontinues to cause increas Is on the populatio n of all three
approach those obtaining during the wet season. In no case shall tests be made in
filled ...ground. Where fissured rock formations are encountered tests shall be b) The physical areas of each of the Islands is small by mainland standards. St. Thomas
made only under the direction and supervision of the Department of Health.' and St. John e no larger than many small mainland towns. SL Croix s only the
size of some of the smallest mainland counties. The construction of an island-wide
The current practice of constructing relatively small leaching areas in some of the sewer network is no great feat considering the small land areas involved.
impervious or slightly pervious clay soils leads one to infer that the required percolation
tests are either not being performed or they are being performed improperly. It is c) Most of the developed land and much of the undeveloped land has already been
extremely important that all percolation test holes be soaked for at least 20 hours before subdivided into small, quarter-acre and alf-acre lots. Municipal sewerage s the
measuring the percolation rate. Automatic siphons or foat valves should be used to only option that can adequately deal with environmental effects of these dense
ensure the hole is always kept full during the soaking period. It is imperative that the developments. It Is too late to institute proper land planning measures to account
soil be allowed to soak for a sufficiently long period of time to allow the soil to approach for the land areas required for individual sewage treatment systems.
wet season moisture conditions and the conditions it will experience if a septic system is
installed in it. d) Municipal sewerage is the only option that allows the government the ability to
eliminate the problems with existing septic systems. Even if regulations could be
Percolation test should not be performed in areas where there is less than four feet of adopted so that all new septic systems would operate safely, those same regulations
naturally occurring soils above the bedrock. Even though these soils may be somewhat would do nothing to address the non-conformance of existing septic systems. It is
pervious, there is not enough depth of soil to properly separate the bottom of in-ground extremely difficult (some would say impossible) to impose new rules and regulations
leaching trenches from the top of fissured bedrock. on the present population and force them to upgrade their existing systems when
poor soils, steep slopes, or other site limitations exist. Tieing into a municipal sewer,
however, is a common and politically acceptable method of undoing past problems
and mistakes.
e) Municipal sewerage is typically the most economical alternative for urban areas. If
treatment capacity exists and only sewer extensions are necessary, costs can ntn in
order of $S,000 per four-member household. If both sewer and new treatment
facilities are required, these costs can increase to S10,000 to $20,000 per four-
member household. Many times federal funds are available to offset much of these
costs, particularly when potential health problems can be documented.
f) Municipal sewage treatment systems are a proven technology. Treatment plants are
servicing the major population centers on all three Islands. Although there are
problems inherent in treating and disposing of large quantities of sewage, at least the RECOIMN DATION #4
problems can be defined addressed, and resolved in a logical manner. Compared to
the situation where thousands of individual on-site sewage treatment systems are Create a propam to provide a method of assuring that public and private age
being operated and maintained by the average homeowner one can appreciate the teatmet pln s (SM) or Innovative systemson l, are operated and maintained
rationale for large sale treatment works. New and innovative technology are more properly ust the following approahe
easily developed for larger sewage flows then individual homes. making the
alternatives greater for municipal systems. Require all ST and alternative systems be designed by a licensed sanitary engineer
and that the design engineer inspect the construction to cerdfy that the plant meets
RECOMMENDATION #3 - Privat Sewage Treatment Plants (3-part recommendation) all the requirements of the USVI regulations and permit condidonr
Create a formal training course for STP operators that leads to STP operator
3A) In those areas that are remote from municipal sewer, require developers to certifiation Require that 11 operators of public and private SIP be certified.
construct priately owned sewage treatment plants (STPs) similar to the EstablLs licensing fees, study guides and xam requirements.
facilities in use at the major resorts.
Require a guarantee of permanent maintenance for private STP or innovative system
3B) Require that al privately owned sewage treatmnet facilities be operated and owners.
maintained by certified treatment plant operators that are employees of the VI
government* Establisb a program of developing a set of enforceable standards concerning effluent
3C) Allow developers the option of providing sewer and the funds for expansion of testing including a strict schedule of sampling and testing by certified laboratories.
municipal STPs in lieu of constructing private Ss
Discussion:
Currently, private community sanitary treatment plants (STPs) are usually owned and
operated by a hotel and condominium developments. The EPA has observed that
typically these associatios are notoriously poor managers of community septic systems
(USEPA, 1977). Regulators therefore generally require appropriate assurances that the
system will be properly operated and maintained before a permit or approval is issued
(USEPA, 1977).
Publicly owned and managed communityon-site STPs serving small residential
developments have been encouraged by the United States Environmental Protection
Agency (USEPA) as effective, environmentally sound, yet less expensive alternatives to
traditional sewage treatment plants, especially in rural and suburban growth areas (Train,
1976; Staudt and Niebhaus, 1982). EPA has encouraged public ownership of such systems
because of the problems inherent In private ownership, which include lack of individual
responsibllrty for a failed system, improper and inadequate maintenance, improper
disposal of household wastes, and lack of alternative sources should the system fail
(USEPA. 1988). When appropriately sited. designed. installed and maintained. multi.
user systems have met with a high degree of success in many situations.
- m - m - - m m - - - -
I:
V V
MARINAS, BOATING AND HYDROLOGIC
MODIFICATION
General
How to Minimize Pollution from Recreational Boating
Lynne MacDonald ....................................... V-1
Marina Siting and Design to Minimize Pollution
Nathalie Peter .............................................. V-7
Marina Operation and Maintenance
Kim Lindlau ........................................ V-18
Technical
Adverse Effects of Dredging
Barbara Kojis and Norman Quinn . ............................ V-20
How to Prevent or Minimize Shoreline Erosion
Dennis Hubbard ................................... V-35
PaperI nt]/abeatieoprnng
* Paper not available at time of printing.
........
HOW TO MINIMIZE POLLUTION FROM RECREATIONAL BOATING
Lynne H. MacDonald
Virgin Islands Marine Advisory Service, University of the
Virgin Islands, St. Thomas, Virgin Islands 00802
INTRODUCTION
Section 6217 of the Coastal Zone Reauthorization Act of 1990
(CZARA) requires states and territories with federally
approved coastal zone management programs to develop and
implement Coastal Nonpoint Source (NPS) Pollution Control
Programs. Requirements for state and territory programs are
described in the Coastal Nonpoint Pollution Program: Program
Development and Approval Guidance developed by the U.S.
Environmental Protection Agency (EPA). One component that
these programs must address is NPS pollution from Marinas and
Recreational Boating.
The Guidance for "Marinas and Recreational Boating", as with
the guidance for the other four categories of NPS
(Agriculture, Forestry, Urban, and Hydromodification),
identifies management measures to prevent or reduce NPS
pollution, or to prevent pollutants from reaching ground or
surface waters. The management measures are intended to
restore and protect coastal waters through the use of various
management practices. A state or territory's NPS Control
Program must specify the management measures it will implement
and these measures must conform with the Guidance. The
management practices a program uses to address the specific
management measures do not need to be specified; any one or
combination of the practices provided by the Guidance can be
incorporated into a program or other,' equally effective
practices can be used.
The use of a "specific measures, variable practices" approach
to address NPS gives states and territories much needed
flexibility to ensure that each program meets the needs and
circumstances of a particular area. As is an all too familiar
problem in the Virgin Islands, inflexible legislation and
regulation can be extremely burdensome and equally
ineffective. The high degree of flexibility inherent in this
program allows for "tailor-made" NPS control programs that
still conform with the Guidance.
MANAGEM NT MEASURES
The management measures for Marinas and Recreational Boating
are divided into two categories: Siting and Design Management
Measures; and, Operations and Maintenance Management Measures
(fig. 1). The measures apply to:
V-1
Figure 1. Categories for Marina and Recreational Boating
Management Measures
-MM, .:;I .E, B OATid: I
I. .
'2tI DESIGN OPERATION/MAINTEXWC
* Any facility that contains 10 or more slips, piers
where 10 or more boats may tie up, or any facility
where a boat for hire is docked;
* Boat maintenance or repair yards that are adjacent
to the water;
Any Federal, State, or local facility that involves
recreational boat maintenance or repair that is on
or adjacent to the water;
* Public or commercial boat ramps;
* Any residential or planned community marina with 10
or more slips; and,
* Any mooring field where 10 or more boats are
moored.
Management measures for marinas are applicable to facilities
and shore-based services that support recreational boats and
boats for hire; they do not address specific boats except to
the extent that a marina can adopt practices that apply to
boats in their facility. Also, the management measures for
siting and design apply to new facilities and to expanding
facilities if there is potential for the expansion to impact
water quality and important habitat.
Siting and design management measures are shown in table 1.
v-2
The next speaker, Ms. Nathalie Peter of the National Oceanic
and Atmospheric Administration (NOAA) will be discussing
"Marina Siting and Design to Minimize Pollution" and so I
won't go into this any further.
Table 1. Siting and Design Management Measures
SITING AND DESIGN MANAGEMENT MEASURES
-MARINA FLUSHING
3 WATER QUALITY ASSESSMENT
HABITAT ASSESSMENT
SHORELINE STABILI ZATION
STORM WATER RUNOFF
3 FUELING STATION DESIGN
SEWAGE FACILITY
Table 2 lists the Management measures and each measures'
objectives) for "Marina and Boat Operation and Maintenance".
To achieve each management measure's objective, practices can
be implemented at existing and new or expanding facilities.
The management practices that are included in the Guidance are
shown in table 3. While the management measures of a state or
territory's plan must be specified and consistent with those
of the Guidance document, the actual practices used to achieve
these measures do not. The practices listed can be used
individually, or in combination to reduce or control nonpoint
source pollutants. As I mentioned earlier, these practices
are not limited to those shown; others that may be more
effective or appropriate for unique situations or
circumstances can be used.
The practices listed in table 3 are all relatively simple and
inexpensive to implement. There are many operational or
procedural practices, such as providing special waste
receptacles for certain wastes, or designating specific areas
for maintenance. A number of these management practices are
designed to education and inform user groups about each
management measure, and so gain compliance with the practices
through increased understanding and awareness of NPS problems
and solutions.
-
Table 2. Management Measures and Objective(s) for Marina and
Boat Operation and Maintenance
MARINA AND BOAT OPERATION AND MAINTENANCE
MAAGE3ENT MEASURES
SOLID WASTE
Properly dispose of solid wastes from operation, cleaning,
maintenance, and repair of boats to limit entry of solid wastes to
surface waters.
FISH WASTE
Promote sound fish waste management through a combination of fish-
cleaning restrictions, public education, and proper disposal of fish
waste.
LIQUID MATERIAL
Provide and maintain appropriate storage, transfer, containment, and
disposal facilities for liquid material, such as oil, harmful
solvents, antifreeze, and paints, and encourage recycling of these
materials.
PETROLEUM CONTROL
Reduce the amount of fuel and oil from boat bilges and fuel tank air
vents entering marina and surface waters.
BOAT CLEANING
For boats that are in the water, perform cleaning operations to
minimize, to the extent practicable, the release to surface waters of
(a) harmful cleaners and solvents, and (b) paint from in-water hull
cleaning.
PUBLIC EDUCATION
Public education/outreach/training programs. should be instituted for
boaters, as well as marina owners and operators,, to prevent improper
disposal of polluting material.
MAINTENANCE OF SEWAGE FACILITIES
Ensure that sewage pumpout facilities are maintained in operational
condition and encourage their use.
'BOAT OPERATION
Restrict boating activities where necessary to decrease turbidity and
physical destruction of shallow-water habitat.
V-4
Table 3. Management Practices for Marina and Boat Operation
and Maintenance.
Diretn hullmaintea pareas regularly. proer f l i u d.
- Perform abrasie: blafsting:- th oin .spray boothe seor .therenosueo.
- Provi-e proper disposal faci ities (dumpsters/coeredbins). :
- Provide facilities 'for recycling of appropriate mater.iats.::
iFISH WASTEAI MANANGEMENT PRACTICES
- WEstablish fish cleaning areas.
h-Ed wucate boanr lean wher im ortance of properl fdisph ea ig .:::.d
ZI, hiurpit." fish composting where appropriate
'"'""o * ' , = I > 2,.. f. . . .':.
I'p': 'ra'ge':." .'.. P ... ..i mateal.-,f- contain spi ::::-: 7- - :.:-:::::.:
-t '-Sep .-;te.:coijntalnersor the- disposal of tastejil,;w:aste gasoline
used antifreeze, and waste diesel, kerosene, and mineral spirits
should be available and clearly labelled.
- Direct marina patrons as to the proper disposal of liquids.
PETROLEUM:CONTROL MIANAGEMENT PRACTICES
- Use auto .shut-off nozzles and promote the use -of fuel/air separators
on air vents or tank: stems :t reduce spillage.
- Promote the useof oil-absorbing materials in the boats' bilges;
examine and replace as necessary. Dispose/recycle accordingly.
BOAT CLEANING MANAGEMENT PRACTICES
- Wash hulls above waterline by hand. Where feasible, remove boat from
the water and clean where debris can be trapped and properly disposed
of.
Use phosphate-free and biodegradable detergents. Don't overuse.
- Discourage the use of cleaners containing ammonia, sodium hypo-
chlorite, chlorinated solvents, petroleum distillates, or lye.
- Do not allow in-water hull scraping or paint removal underwater.
PUBLIC EDUCATION MANAGEMENT PRACTICES
- Signage
- Recycling/Trash Reduction Programs
- Pamphlets or Flyers, Newsletters, Inserts in Billings, etc.
- Meetings and Presentations
MAINTENANCE OF SEWAGE FACILITIES MANAGEMENT PRACTICES
- Arrange maintenance/service contracts for pumpout facilities.
- Develop regular inspection schedules.
- Maintain a dedicated fund for pumpout station repair and maintenance
(for Government-owned facilities).
- Mandate pumpout use and specify penalties for failure to comply in
slip lease agreements.
- Put dye tablets in holding tanks to discourage illegal disposal.
BOAT OPERATION MANAGEMENT PRACTICES (applies to boating
only)
- Exclude motorized vessels from areas that contain important shallow-
water habitat.
- Establish and enforce no-wake zones to decrease turbidity.
V-5
PUBLIC EDUCATION
It is apparent from the listed practices that public education
is an important ,component of the management measures. Not
only is "Public Education" a specific management measure -- a
required part of any program -- there is also an education-
related practice associated with virtually all of the other
measures.
Public participation and involvement in developing,
implementing and continuously improving a nonpoint source
reduction program is imperative for it's success. A Public
Education/Information campaign must be the very first step in
this process at the territory-level. A program cannot be
effectively put into place without the awareness, cooperation
and assistance of the community.
CONCLUSION
Many diverse sources of pollutants from marina and
recreational boating operation and maintenance can be
eliminated or reduced through the use of some very simple,
economical means. The management measures and practices to
control NPS pollution from recreational boating are direct and
inexpensive. Small improvements in water quality within a
marina or bay can be achieved through the implementation of
any of these; a comprehensive program incorporating a number
of practices can result in significant improvements in marina
water quality.
The key to a successful NPS Control Program is public
education and involvement in the entire'program development
and implementation process. With increased public awareness
through participation and education, the management practices
that are put into place can effectively minimize nonpoint
source pollution from recreational boating.
V-6
MARINA SITING AND DESIGN TO CONTROL
NONPOINT SOURCE POLLUTION
Nathalie Peter
National Oceanic and Atmospheric Administration
Office of Ocean and Coastal Resource Management
Silver Spring, Maryland
Marinas and recreational boating are increasingly popular uses
of coastal areas and an important means of achieving coastal
access. The Virgin Islands, known as the "Charter Capital of
the World," has a large number of resident and transient
vessels. throughout the year. There are 20 marinas in the
Virgin Islands. In 1991, DPNR registered 4.,044 vessels and
issued 719 mooring permits. According to the 1992
Strickland/Quinn report on marine facilities, 70% of the
marine community that were surveyed noted the significant
relationship that exists between the health of the marine
environment and the success of their businesses.
When marinas are poorly sited and designed, they pose a
nonpoint source (NPS) pollution threat that can affect public
health and marine ecosystems. Because marinas are located
right on the water's edge, there is often no buffering of the
release of pollutants to the sea. Adverse environmental
impacts can include:
poorly flushed waters with low dissolved oxygen and
increased petroleum hydrocarbons, pathogens, and
metals.
pollutants transported in stof m water runoff from
parking lots, roofs, and other impervious surfaces.
physical alteration or-destruction of wetlands and
other bottom communities during construction and
operation.
pollutants generated from boatyard and marina
operation and maintenance activities that
contaminate bottom sediments. For example, copper
is a major contaminant because of its use in
antifouling paints.
shoaling and shoreline erosion.
There are numerous territorial and federal regulatory programs
that apply to marinas. Today, however, I will concentrate on
the 6217 Nonpoint Source Pollution Control Program that
Congress included in the 1990 CZMA Reauthorization Amendments.
It applies to all states and territories with approved Coastal
Zone Management Programs (CZMPs). Most of the material in my
V-7
presentation comes directly from the marinas chapter of
Guidance Snecifvina Manaaement Measures for Sources of
Nonnoint Pollution in Coastal Waters (6217 Guidance), released
jointly by EPA and NOAA in January 1993.
Management measures are defined as:
economically achievable measures for the control of the
addition of pollutants from existing and new categories
and classes of nonpoint sources of pollution, which
reflect the greatest degree of pollutant reduction
achievable through the application of the best available
nonpoint pollution control practices, technologies,
processes, siting criteria, operating methods, or other
alternatives.
Fifteen Marina Management Measures, classified as "Siting and
Design" or "Operation and Maintenance" Management Measures,
are included in the Guidance. ii.-iitr iiarina Management
Measures are comprehensive in their coverage of .sources of
nonpoint pollution associated with marinas.
The following operations and facilities are covered by the
6217 Marina Management Measures:
piers and marinas with 10 or more slips;
any facility where a boat for hire is docked;
boat maintenance or repair yards;
public or commercial boat ramps;
residential or planned community marinas with 10 or
more slips; and,
any mooring field where 10 or more boats are moored.
All of the following siting and design management measures
apply to new and expanding marinas. In addition, the storm
water runoff management measure applies to dxisting marinas
and boatyards for at least the hull maintenance areas'.
A. Flushing Management Measure
The first management measure is the marina flushing management
measure which is to be applied to new and expanding marinas.
it is to It fslite and desian marinas such that tides and/or
currents will aid in flushina of the site and renew its water
reaularlv.11
If a marina does not flush properly, there is a potential for
waters to stagnate and for pollutants to concentrate to
unacceptable levels in the water and/or bottom sediments,
resulting in impacts to the biological resources. Flushing
time can range from several hours to possibly several weeks,
depending upon the location of a marina in a waterbody and its
configuration.
V-8
In the Virgin Islands, flushing is primarily due to (1) the
movement of the tidal prism and currents in and out of a
marina waterbody and (2) wind-driven circulation.
The degree of flushing necessary to maintain water quality in
a marina should be balanced with safety, vessel protection,
and sedimentation. Flushing guidelines can be developed for..
different regions and different conditions. For example, in
Florida'where tidal range does not exceed i meter, a flushing
reduction of 90% over a 24 hour period has been recommended.
Practices
In addition to specifying management measures, the §6217
Guidance also provides management practices that can be
applied successfully to achieve, the management measures.
However, the application of these practices needs to be tied
to the NPS pollution source, the specific site, and the
climate. This is especially true in the Virgin Islands where
the climate is tropical; the topography is steep slopes; soil
cover is thin; and suitable shoreline is limited and costly.
While most of the siting and design practices in the §6217
Guidance appear to be appropriate for the Virgin Islands, the
territory may find that alternative practices will be more
effective in controlling NPS pollution.
1. There are a number of practices in the Guidance to
achieve adequate flushing. One practice is to site and
desian marinas such that the bottom of the marina and the
entrance channel are not deeper than the adjacent
naviaable waters, unless it can be demonstrated that the
bottom will support a natural population of benthic
organisms.
Existing water depths necessarily 'affect the entire
marina layout and design so bathymetric surveys should be
conducted for a proposed basin and approach channel.
Marina basin and channel depths should be designed to
gradually increase toward open water to promote flushing.
Otherwise, isolated deep holes where water can stagnate
may be created.
2. A second practice is to desian marinas with as few
seaments as possible to promote circulation within the
basin. Flushing efficiency is. inversely proportional to
the number of segments. For example, a one-segment
marina will not flush as well as a marina in open water,
and a two-segment marina will not flush as well as a one.
segment marina. The physical layout of a marina, as
determined by the orientation of the marina toward the
natural water flow, can also have a significant effect on
the flushing capacity. Ideally, the distance between the
exchange boundary and the innermost portion of the basin
is minimized; otherwise' elongation increases circulation
time.
V-9
There will be better dissolved oxygen (D.0.) conditions
in marinas that avoid improper channel entrance designs,
bends, and square corners. These areas tend to trap
sediment and debris. If square corners are unavoidable,
then access points should be provided to allow easy
cleanout of accumulated debris.
3. In Doorlv flushina waterbodies. consider desian
alternatives to enhance flushina: an open marina basin
over a semi-enclosed desian: wave attenuators over a
fixed structure. A marina at the head of an embayuent
will normally have poorer flushing than one located near
the opening. Obviously, safety and vessel protection
will weigh heavily in this sort of siting decision.
4. Another practice is to desian and locate entrance
channels to promote flushina. Entrance channel alignment
should follow the natural channel alignment as closely as
possible to promote flushing. Any bends that are
necessary should be gradual. In the Virgin Islands where
the tidal range is small, the marina entrance should be
designed to be as wide as possible to promote flushing
while still affording vessel protection. Entrance
channels aligned parallel to the direction of the
prevailing winds also promote circulation.
If the entrance channel is perpendicular to the waterway,
shoaling can be a problem in areas of significant
sediment transport due to currents. Shoaling can require
increased maintenance dredging of the channel and can
lead to water quality problems by reducing circulation.
The orientation and location of a solitary entrance can
impact marina flushing rates. When a marina is square or
rectangular, a single entrance at the center of the
marina produces better flushing. If -a marina is
circular, an off-center entrance channel will promote
better circulation.
5. Establish two oneninas. where appropriate. at oouosite
ends of marina to promote flow-throuah currents. In
situations where both openings cannot be used for boat
traffic, a smaller outlet can be opened solely to enhance
flushing. In other situations, a buried pipeline has
been used to promote flushing.
6. The last practice has to do with land use: designate
areas that are suitable and areas that are unsuitable for
marina develoDment. Provide advance identification of
waterbodies that do or do not experience adequate
flushing. Several years ago, Puerto Rico completed a
marina siting study for the northeast coast. It is now
uses as a basis for marina permit decisions in the
commonwealth.
¥-10
B. Water Quality Assessment Management Measure
iiThe second management measure is to " MI ssess water crualitv as
uart of marina sitincr and desian. 1 This management measure
does not require a study per se but rather an assessment of
water quality.
Assessment of water quality may be used to determine whether
This may entail:
ii (1) pre-development and/or post-development monitoring
of a marina or amnbient waters;
(2) numerical or physical modeling of flushing and
II water quality characteristics; or
(3) both.
Cost impacts may preclude a detailed water quality assessment
for marinas with 10-49 slips. A pre-construction inspection
and assessment can still be expected, however.
Historically, water quality assessments have focused on two
parameters: DO and pathogen indicators. DO levels may be
used as a surrogate variable for the general health of the
aquatic ecosystem. Pathogen indicators are used as a
surrogate variable for assessing risk to public health through
F ingestion of contaminated water and shellf ish and through
bathing. Water quality assessments can be used to ensure that
water quality standards supporting a designated use are not
exceeded.
North Carolina conducted a post-development marina study to
characterize the water quality conditions of several marinas
and to provide data that can be used to evaluate future
Providing water quality information is already required
nationwide when dredging is involved. Dredging a marina site
or entrance channel requires a River and Harbors Act section
10 permit from the U. S. Army Corps of 'Engineers. If there is
discharge into U.S. waters after dredging, then a Clean Water
Act section 404 permit is required. DPNR would issue a
section 401 water quality certification before the Corps would
issue a section 404 permit. Section 10 and section 404 both
require a permit applicant to present to the Corps information
necessary for a water quality assessment. An expert
knowledgeable in water quality and hydrodynamics may assess
potential impacts using available information and site
inspection.
V-Il
As part of the section 401 water quality certification
process, DPNR requires information about water quality. The
Department needs to look at this certification process to see
if it adequately addresses nonpoint source impacts.
C. Habitat Assessment Management Measure
The third management measure is to ,rSi its and desian marinas
to protect aaainst adverse effects on shellfish resources.
wetlands. submeraed acuatic veaetation. or other imnortant
riDarian and aauatic habitat areas as designated by local.
state. or federal aovernments.1
Coastal marinas are often located in estuaries, one of the
most diverse of all habitats. The Mangrove Lagoon on St.
Thomas is a good example of this. Estuaries contain many
plant and animal communities that are of economic,
recreational, ecological, and aesthetic value. These
communities are frequently sens--itiveto habitat alteration
that can result from marina siting and design. Biological
siting and design. provisions for marinas are based on the
premise that marinas should not destroy important aquatic
habitat, should not diminish the harvestability of organisms
in adjacent habitats, and should accommodate the same
biological uses have been classified. Important types of
habitat for an area, such as wetlands and coral reefs, are
usually designated by local and federal agencies. In some
situations, however, the locations of all important habitats
are not known. Geographic- information systems show promise as
a method of conveying important habitat and other siting
information to marina developers and environmental protection
agencies.
Currently, DPNR requires a habitat assessment in the
Environmental Assessment Report (EAR) that is submitted as
part of a coastal zone management major permit application for
a marina.
Some of the practices in the §6217 Guidance associated with
habitat assessment are already followed in the Virgin Islands.
The practices are as follows:
1. Conduct surveys to characterize the Droiect site.
Characterization of a proposed marina project site
is the first step to determine compatibility. This
would include evaluation of physical properties,
water quality characteristics, and available
habitat and seasonal use of the site by benthic
species, macroinvertebrates, resident and transient
fish, birds, endangered species, etc.
2. RedeveloD coastal waterfront sites that have
previously been disturbed; expand existina marinas
or consider alternative sites to minimize potential
environmental impacts.
The Virgin Islands should use caution with this
practice since many marinas here may have been.
designed at the maximum sustainable size in the
first place. This is especially important in areas
identified as Areas for Preservation and
Restoration and Significant Natural Areas.
3. EmDlov rapid bioassessment techniques to assess
impacts to bioloaical resources.
Rapid bioassessment uses biological criteria and is
based on comparing-the-community assemblages of the
potential development site to an undisturbed
reference condition.
4. Assess historic habitat function (e.a.. sDawnina
area. nursina area. miaration pathway1 to minimize
indirect impacts.
5. Minimize disturbance to indiaenous veaetation in
the riparian area.
Riparian areas are the vegetated ecosystems along a
waterbody. They are generally more productive
habitat, in both diversity and biomass, than
adjacent uplands. They serve an important nonpoint
source pollution control function in the Virgin
Islands: mangroves reduce sedimentation; salt
ponds filter storm runoff prior to its entry into
coastal waters. Disturbance'should be minimized or
disallowed altogether.
6. Finally, the territory could develop a marina
sitina volicv to discouraae development in areas
containina important habitat as desianated bv
territorial and federal aaencies.
This type of land use policy would be useful in
such places as Salt River. It could be
incorporated into the proposed comprehensive Land
and Water Use Plan or APC/APR management plans.
D. Shoreline Stabilitization Management Measure
"Where shoreline erosion is a nonpoint pollution problem.
shorelines should be stabilized. Veaetative methods are
stronalv preferred unless structural methods are more cost
effective. considerina the severity of wave and wind erosion.
offshore bathvmetrv. and the potential adverse impact on other
shorelines and offshore areas."
Shoreline erosion is not always a NPS pollution problem, but
where it is, the shoreline should be stabilized. (It is
usually in the best interest of the marina operator to
minimize erosion anyway to reduce sedimentation and the
frequency of dredging). The Virgin Islands is fortunate to
have red mangroves which are relatively easy to plant under
the right circumstances and offer excellent shoreline
protection. Another advantage of this vegetative protection
is its affordability. But mangrove effectiveness varies with
the amount of wave reduction provided by the physiography and
offshore bathymetry of the site.
In some cases, structural techniques such as gabions, riprap,
and sloping revetments can dissipate wave energy that can
cause erosion. Bulkheads, jetties, and breakwaters are other
structural methods to stabilize shorelines and navigation
channels, but they may also cause scouring in front of the
structure and increase erosion of the adjacent shoreline.
E. Storm Water Runoff Management Measure
,,Implement effective runoff control strateaies which include
the use of pollution prevention activities and the proper
desian of hull maintenance areas.
',Reduce the averaae annual loadinas of total suspended solids
ITSS) in runoff from hull maintenance areas by SO Dercent.
For the purposes of this measure. an 80 Dercent reduction of
TSS is to be determined on an averace annual basis."
This management measure is intended to be applied by states
and territories to new and expanding marinas, and to existing
marinas for at least the hull maintenance areas. If boat
bottom scraping, sanding, and/or painting is done in areas
other than those designated as hull maintenance areas, the
management measure applies to those areas as well. This
measure is not applicable to runoff that enters the marina
property from upland sources.
The principal pollutants in runoff from marina parking areas
and hull maintenance areas are suspended solids and organics
(predominantly oil and grease). Toxic metals from boat hull
scraping and sanding are part of, or tend to become associated
with, the suspended solids. The proper design and operation
of the marina hull maintenance areas is a significant way to
prevent the entry of toxic pollutants from marina property
into surface waters. Recommended design features include the
designation of discrete impervious areas (e.g., cement areas)
for hull maintenance activities; the use of roofed areas that
prevent rain from contacting pollutants; and the creation of
diversions and drainage of off-site runoff away from the hull
maintenance areas for separate treatment. Source controls
that collect pollutants and thus keep them out of runoff
include the use of sanders with vacuum attachments, the use of
V-J4
large vacuums for collecting debris from the ground, and the
use of tarps under boats that are being sanded or painted.
The perviousness of non-hull maintenance areas should be
maximized to reduce the quantity of runoff. Maximizing
perviousness can be accomplished by placing filter strips
around parking areas. Swales are strongly recommended for the -
conveyance of storm water instead of drains and pipes because
--of their infiltration and filtering characteristics.
Suspended solids are solid materials that remain suspended in
the water column. The annual TSS loadings can be calculated
by adding together the TSS loadings that can be expected to be
generated during an average 1-year period from precipitation
events less than or equal to 2-year/24-hour storm. The 80
percent standard can be achieved, by reducing over the course
of year, 80 percent of these loadings. EPA recognizes that 80
percent cannot be achieved for each storm event and
understands that TSS removal efficiency will fluctuate above
and below 80 percent for individual storms. The 80 percent
removal of TSS is applicable to the hull maintenance area
only. Although pollutants in runoff from the remaining marina
property are to be considered in implementing effective runoff
pollution prevention and control strategies for all marinas,
existing marinas may be unable to economically 'treat storm
water runoff.
These are a number of techniques for controlling maintenance
area runoff. They include .(I) filtration/infiltration, (2)
retention, detention, and (3) physical separation of
pollutants. Because these were covered in the storm water
runoff session, I will not get into them here. Please refer
to the §6217 Guidance for additional details.
Because of the steady breezes, heavy downpours, soil types,
and limited land areas suitable for haulout facilities in the
Virgin Islands, source controls at marinas such as sanders
with vacuum attachments may be more appropriate for both
health and NPS pollution control purposes than filters,
strips, wet ponds, infiltration basins and trenches, or
grassed swales.
F. Fueling Station Design Management Measure
Another sound objective in designing a marina is to -[Dlesiern
fuelina stations to allow for ease in cleanup of spills."
This is required under the §6217 program for new and expanding
marinas where a fueling station is being added or moved, but,
for the most part, it is already required in the Virgin
Islands under other territorial and federal authorities.
The possibility of spills during fueling operations always
exists. Since most petroleum-based fuels float on the water's
surface, this allows for their capture if containment
V-15
equipment is uses in a timely fashion. The following
practices can be applied successfully to achieve this I
management measure.
1. Locate and desicn fuelina stations so that spills
can be contained in a limited area.
Fuel station location and design should be such
that booms can be deployed to surround a spill.
2. Desicn a SDill Continaencv Plan.
A plan that meets local and federal requirements is
probably already required in the Virgin Islands for
fuel storage and dispensation areas. Marina
personnel should be properly trained in spill
containment and control procedures.
3. Desian fuelina stations with suill containment
eauiDment.
Appropriate equipment should be stored in a clearly
marked, easily accessible cabinet or locker.
G. Sewage Facility Management Measure
"Install Dumnout. dumD station. and restroom facilities where
needed at new and exPandina marinas to reduce the release of
sewace to surface waters. Design these facilities to allow
ease of access and Dost sionace to promote use by the boatina
public. "
This management measure applies to new and expanding marinas
in areas where adequate marine sewage collection facilities do
not exist. Pumpout stations are for vessels equipped with
marine sanitation devices (MSDs) and dump stations are. for
vessels with portable toilets. A marina should chbose a
pumpout facility and/or dump station based on the types of
vessels it services. In the Virgin Islands, there currently
are not any pumpout stations in operation.
There are (1) fixed point systems, (2) portable/mobile
systems, and (3) dedicated slipside systems.available. Fixed
point collection systems are generally located on the end of
pier, often near the fueling station so that pumpout and
fueling operations can be combined. Pumps or vacuum systems
remove sewage from the vessels to an approved disposal
facility.
A portable unit includes a pump and a small storage tank. In
mpny cases, these units are considered the most logistically
feasible, convenient, accessible, and therefore, economically
affordable method for a marina. In some locations in the
V-] 6 I
V-I16
U.S., a radio dispatched pumpout vessel will service vessels
in a marina or mooring field.
Dedicated slipside systems provide continuous wastewater
collection at a marina slip for vessels equipped with MSDs.
These are appropriate for liveaboard vessels in a marina.
Adequate signage should be provided to advertise pumpout
service availability and public restroom facilities.
H. Other Design Considerations
During the design phase of a marina, attention to the
environmental concerns of marina operation will significantly
reduce the potential for NPS pollution from day-to-day
activities. Siting and design of trash facilities, waste oil
and other liquid disposal site, n--d fish cleaning and
disposal sites should be key considerations in marina layouts.
Adequate and well-marked facilities in appropriate, protected
locations within the marina can minimize the entry of
pollutants into marina waters.
In addition to proper marina siting and design considerations,
public education for boaters and marina operators can go a
long way toward preventing NPS pollution.
Conclusion
In conclusion, many factors influence the long-term impact
that a marina or boatyard will have on water quality and
habitat in the immediate vicinity of the marina and the
adjacent waterway. Initial marina site selection is the most
important factor. A site with favorable hydrographic
characteristics that requires the least amount of modification
can reduce potential NPS impacts. Whether a marina is open or
semi-enclosed and its configuration will affect its
circulation and flushing characteristics. The final design is
usually a compromise that should produce a favorable
combination of marina capacity, services, and access while
minimizing environmental impacts, dredging requirements,
protective structures, and other site development costs.
V-17
MAR IM OPERATION AMD XAINTENANcE/OUR FRAGILE ENVIRONMET I
Kiln S. Lindlau
American Yacht Harbor, Red Book, St. Thomas, USVI 00802 I
We must protect our natural resources through awareness,
education and communication. I
The marine industry plays a very large part of the overall
economy of our islands. Vessels travel great distances to
enjoy and share our beautiful pristine waters. The United I
State Virgin Islands have much to offer the boating industry,
we have location, climate, and almost constant trade winds. By
the same token the boats are the life sustaining force for
many marine re'lated businesses.- Over -the past f ew years we I
have lost numerous vessels to other islands due to incentives
and lower operational costs. Hurricane Hugo also lowered the
overall size of the f leet. Both losses have af fected the
marine industry which directly affects the Islands economy.
Not only should we be aware of the positive impact these
vessels have on our islands, we should also be aware of the
environmental mishaps that can occur if proper education and
communication is not available.
My office operates with an open door policy. Should a problem
occur on land side or water side, chances are i've had
dealings with it in the past. Response time is very important
as part of the final result. Therefore as soon as a manager
is made aware, the sooner actions can be taken to correct it.
Again Communicate. I believe this policy works for any
business.
The ownership, management and staff of American Yacht Harbor
are environmentally aware of their surroundings. The
redevelopment which is in progress has taken into account not
only the federal and local rules and regulations which govern
us but future rules and regulations. The fuel system was
designed to meet all EPA requirements. We have fiberglass
double walled tanks and lines. We also use three different
types of leak detection.
1. Leak detection at the tanks..
2. Accounting fuel inventory.
3. DPNR Petroleum Inventory Control Form.
Petroleum products are very damaging to our environment. The
waste oil problem has been affecting these islands for many
years. However, there has been a waste oil committee formed
to find a long term solution to this problem. The membershipI
includes very dedicated people from the government and private
sector.I
V 18
For years waste oil has been disposed of in dumpsters,' poured
ii in guts or just poured along the side of the road. Probably
sooner than later this oil will reach our coastal waters,
pollute our wells and contaminate our water table. Storma ran
of f and saturation will speed this process along. When an
ii agreeable solution is found, a massive 'educational program
will follow to stop this type. of pollution. At this time
double containment and very strict maintenance programs are-
ii recommended, not only for the marine environment but for all
of us.
ii American Yacht Harbor has had double containment for a number
- of years and the location is visited on a regular basis by a
staff member. it is very important to keep the surrounding
area clean and clear of small, full containers of oil. We
have seen everything from open coffee cans to 5 gallon
containers with the lids full of oil, rainfall then
complicates the matter by spreading it into the containment
p area on the ground. We have a oil boom and until recently
only absorbent pads (which unfortunately absorb more water
than contaminate). We have now added to our inventory a
product called Spil CAT.
Spil CAT:
P 1. Encapsulates oily liquids on contact and
prevents them from causing further damage to the
environment.
9 2. Floats and will remain floating after
application on spills.
9 3. Is lightweight
9 4. Absorbs sixty times its weight.
5. Will not absorb water.
9 6. is non-toxic.
7. Non-flammable.
8. Non-hazardous.
J 9. Non-corrosive.
10. Has a long shelf life.
It appears this product is environmentally friendly and can
reduce costs in oil cleanup plus help protect our ecosystem.
In closing, it's our environment, let's take care of it to the
best of our ability. Remember the agencies here today are
here to help us. They don't expect anyone to'know all the
answers but they do hope we know the proper questions to ask.
v-I 9
M; -Ii1
oo NB UQUtDNOBB DREDGING }OBZhL fBBBI1JS e.
IN THE WESTERN PaCIFIC OCN MND IX BR8- AROUND
ST THOMAS / ST JOEN, U.S. VIRGIN ISLANDS I
N.J. Quinnl and B.L. Kojis2
lEastern Caribbean Center, University of the Virgin Islands,
No. 2 John Brewers Bay, St. Thomas, United States Virgin
Islands 00802. Department of Planning and Natural
Resources, Government of the Virgin Islands of the United
States, St. Thomas, United States Virgin Islands 00802.
INTRODUCTION
Many dredging projects are related to people's desire to I
travel, engage in trade, fill or enhance shorelines, or,
particularly in the Pacific, establish military bases. On
small islands airports are usually located in the coastal I
zone and often substantial lands have to be filled and
causeways constructed to provide land for runways and termi-
nals. Docks and ports must be located at the shoreline and
frequently require shoreline alteration and sea bed modifi-
cation to accommodate vessels. Dredge spoil has been used to
fill submerged lands, to provide cover for garbage dumps,
and to enhance beaches. U.S. expansionist interests during
the Cold War resulted in dozens of remote military bases
being constructed on uninhabited islands in the Pacific
Ocean. Many of these islands required major dredge and fill
operations to accommodate military activity.
PHYSICAL CONSEQUENCES I
The following lists the probable effects of mechanical exca-
vation and dredging:
1) the bottom is physically disturbed and habitat for
bottom dwelling organisms removed,
2) sediment is deposited on the sea bottom,
3) sediment is suspended in the water column,
4) toxic substances are reintroduced into water
column,
5) light penetration is reduced,
6) the oxygen content of the water is reduced,
7) turbidity increases,
8) circulation patterns change,
9) dissolved oxygen levels are reduced,
10) nutrient levels increase, and
Quinn and Kojis
Dredging Consequences
11) indirect damage is caused by anchors, moorings and
slurry pipes.
The most widespread and visible consequence of dredging and
excavation is the generation of suspended sediments and tur-
bidity. This paper will focus on the ecological aspects that
are the result of the physical consequences of dredging.
ECOLOGICAL CONSEQUENCES
An unavoidable impact of any dredging operation is the
direct elimination of the bottom habitat in the dredged area
and loss of associated species. The accumulation of sediment
on the bottom in adjacent areas can also have a significant
adverse leffect on the animals and plants on the bottom.
Depending upon the extent of the alteration caused by dredg-
ing, recolonization may eventually be possible on many
dredged surfaces. However, it generally takes a long time,
perhaps several decades, for the fauna and flora to return
to its original state. Harbor bottom environments tend to
accumulate fine sediments and are most often colonized by
soft-bottom or sand-dwelling communities. If the orginal
harbor bottom was a seagrass community, it may be many years
before this type of community return. Dredged hard surfaces
that are not deep (greater than 30 ft depth) and exposed to
waves and currents (such as quarry holes on outer reef flats
in the Pacific) can be extensively recolonized by reef life
within a decade following dredging (Maragos, 1987).
The recolonization of hard substrate in the Caribbean is
poorly known and needs additional study. Currently we are
investigating colonization of reefs in three sites around
St. Thomas, but results are not expected for some time.
Corals and many other reef organisms are adapted to clear
waters and are particularly susceptible to turbidity caused
by dredge and fill operations. Knowledge of currents in the
construction area allows prediction of direction and persis-
tence of turbidity plumes, thereby facilitating assessment
of potential impacts of dredging surrounding marine communi-
ties.
Studies by Kojis and Quinn (1984) found that the ability of
corals to reproduce was affected by the levels of sedimen-
tation at various sites. Corals living in regions of high
turbidity released fewer larvae and only grew in shallow
water. A smaller zone of living reef reduces the area which
associated reef fish may live and in effect reduces the pro-
ductivity of an area. Over a prolonged period of time high
sediment loads result in lower diversity, percent cover, and
growth rates of coral species, smaller colony sizes, an
V-21
Quinn and Kojis
Dredging Consequences j
upward shift in depth zonation, and a predominance of resis-
tant growth forms or species (Rogers, 1990). I
There have been few studies that address the effects of sus-
pended sediments on growth and mortality of individual coral
species. Field studies have demonstrated that growth rates
of the Caribbean mountainous star coral (Montastrea
annularis) diminish as sediment loads increase (Dodge, et
al., 1974; Hubbard, et al., 1987). However, workers in the
Pacific have found that there was little or no evidence of
decreased growth rate for surviving colonies of Porites
lutea (a species often found in turbid waters) even in areas
where high mortality of other coral species has been
attributed to the effects of sedimentation (Hudson, et al.,
1992). Laboratory e iments evaluated the. resistance of
seven coral. species found in the subtropical waters off
Tampa Bay to 49 to 199 mg per liter of suspended natural
marine sediments for 10 days. Although growth rates
decreased, all corals survived (Rice and Hunter, 1992).
Local currents and exposure to wave action also play a role
in recruitment and survival rates of marine organisms.
Variation in these rates determine the distribution and
zonation of corals and other marine life. Consequently,
dredging and the resultant physical modification of topo-
graphic features that may alter current regimes and exposure
to wave action also can have profound effects on reef commu-
nity structure in a surrounding area.
Indirect impacts of dredging include anchoring operations
for barges, ships, and pipelines. Placement and dragging of
anchors and pipes over sensitive ecosystems can damage
coral, and to a lesser extent, plant communities.
ECOLOGICAL CONSEQUENCES: DOCUMENTED EXAMPLES I
A. Pacific Ocean
1. Federated States of Micronesia
At Okat Reef, Kosrae, Federated States of Micronesia
(Fig. 1), the rate of slurry discharged into a reten-
tion basin exceeded the basin's capacity, causing
slurry to overflow the walls, spill out over 25 acres
of seagrass and coral habitat, and completely bury it
under 0.8 to 1.5 feet of fine slurry muds. The impact
could have been prevented by a reduced rate of slurry
discharge, but the construction contractor had a sched-
ule to meet and was unwilling to slow operations
(Maragos, 1984). Dredging further destroyed reef and
sea grass meadows and greatly altered circulation in
Quinn and Kojis
Dredging Consequences
the harbor. The stronger water currents were implicated
in shoreline erosion near the airfield -and Tafunsak
Village. The impacted reef was once Kosrae's most
important fishing ground. Fish yields at Okat reef have
declined to half of preconstruction levels (Maragos,
1984).
2. Kaneohe Bay,.Hawaii
Military dredge and fill operations between 1938 and
1950 increased circulation in the north part of Kaneohe
Bay, Oahu, Hawaii, but reduced circulation in the south
part (Fig. 2). Additonally, the southern part of the
bay was impacted from sewage outfalls constructed in
1950. By 1970, only northern bay reefs were recovering
while cehtral--and southern bay -re-c e-clined' because
of sewage pollution.
The sewer outfalls were removed from the bay during the
years 1977-1978, allowing for coral recovery in the
central and southern bay. The recolonization of corals
on dredged surfaces was accelerated after removal of
sewage outfalls in the nearby lagoon and relocated to
outside the lagoon. The discharge of primary treated
sewage does not appear to have adversely affected the
reefs because of it us discharged at a depth of 35 m
and there is excellent mixing and flushing at the new
site (Maragos, et al., 1985).
3. Taongi Atoll
Many enclosed Pacific atolls have elevated lagoon water
levels because of wave action pumping water over wind-
ward reefs and the lack of large, deep channels' to
drain the excess water. The reefs grow above normal
ocean sea level because of constant water flow and the
resultant elevated water level. Dredging a deep channel
through such an atoll reef causes waters to drain more
quickly, lowering the lagoon water level and killing
emergent reefs. This occurred at Taongi Atoll (Fig. 3)
(Maragos, 1989).
4. Palmrya Atoll, U.S. Line Islands
Construction of road causeways around the East Lagoon
at Palmyra Atoll, U.S. Line Islands by the U.S. Navy
completely blocked circulation, causing collapse of
coral reef communities (Fig. 4). Dredging of a channel
through the western reef and between the central and
east lagoons destroyed reefs and altered water
circulation. Sediments drifting west from the dredge
and fill areas damaged reef communities off the western
end of the atoll. By 1979, some of the northern
V-2 3
Quinn and Kojis
Dredging Consequences
causeways had breached restoring some exchange between
the east lagoon and the Pacific Ocean. Observations in
1987 found only partial recovery of the reefs from
military construction (Maragos, 1979; 1987).
B. Virain Islands
Numerous dredging activities have occurred in the Virgin
Islands. These activities range from small localized
activities to maintain channel depth to the larger dredging
projects to maintain harbors and fill wetlands. Among the
major dredging projects in the U.S. Virgin Islands are two
that exemplify some of the changes and problems created by
dredging: Great Cruz Bay, St. John and at Water Bay, St.
Thomas.
1. Great Cruz Bay
The dominant biotic feature of Great Cruz Bay is an
algal sea grass meadow characterized by Manatee and
Turtle grass interspersed with worm hummocks and green
algae such as Penicillus, Udotea and Halimeda. Queen
conch and the long-spined black sea urchin were once
common, and healthy fringing coral reefs were present
along the northwestern and southwestern shore
(vanEepoel & Grigg, 1970).
In 1968, dredging of 186,000 cu. yd. was permitted in
the bay to a depth of 15 ft within 300 ft of the shore
(Fig. 5). The area dredged was a rich seagrass and
algal meadow. The bulk of the dredge spoil was used to
fill in wetlands while the rest was used for con-
struction in the Hyatt Regency Hotel. Dredging
occurred at the same site in 1985.
Although the Corps of Engineers 1968 permit required
compliance with federal and local regulations regarding
water pollution, no attempt was made to minimize the
quantity of fine material in suspension in the water.
However, despite this, the predicted destruction of the
benthic biota outside the dredged area (vanEepoel and
Grigg, 1970) did not occur. In 1985, the area was
dredged again. Eight years later in August 1993, we
found the dredge site characterized by soft sediments
inhabited by burrowing organisms, little algae, and no
sea grass.
The water clarity, measured using a Secchi disc, in the
dredged area was 1.6 ft in 1970 (vanEepoel and Grigg,
1970). When we sampled water clarity on a calm day in
August 1993, the Secchi disc reading was 4.5 ft. This
is still poor and unattractive compared to the clearer
V-24
Quinn and Kojis
Dredging Consequences
water over the sea grass meadows near the entrance of
the bay. In both 1970 and in August 1993, the sea grass
meadows near the entrance of the bay could be clearly
seen (>20 ft deep).
2. Water Bay
Between 1961 and 1970, a ten year period, approximately
750,000 cubic yards of sand were dredged from Water Bay
(Fig. 6) for various land fill, construction, and beach
nourishment projects. This dredging operation removed
the bottm cover of sea grasses and algae. The result
was that fine sand and silt particles were no longer
trapped and turbidity remained_,nmdesirablel. _(Grigg and
van epoel., 1970).
During the ten year period that dredging occurred, the
living animals on the fringing reef on the east side of
the bay gradually died. These changes were called "...
a major ecological disaster for the sub-littoral flora
and sessile fauna" (vanEepoel, 1969). While not on the
order of a Gulf of Valdez oil spill, the gradual
destruction of habitat diminished the productivity and
natural beauty of the territory's coastal waters.
Dredging of Water Bay not only destroyed habitats, it
also was responsible for loss of sand from Sugar Bay
Beach. Originally it was believed that the presence of
the dredge holes in Water Bay promoted "slumping" of
the Sugar Bay beach sand into the holes (Brody cited in
VIMA, 1992). However, various reports describe the
stockpiling of sand on the eastern end of Sugar Beach
which would have required the slurry pipes to traverse
the live reef and this would have damaged the reef. A
recent theory is that as a result of the damage to the
reef, Sugar Beach was provided less wave protection and
severe erosion occurred (VIMA, 1992). Specifically, as
a result of physical damage to coral (primarily elkhorn
corals) caused by the pipes, the height of the reef
surface was lowered, increasing wave energy which
rapidly eroded the beach (VIMA, 1992). The clean, car-
bonate sandy beach became dominated by 10-20 cm cob-
bles. The beach in its present condition does not pro-
vide easy access to the sea for bathers and diminishes
the appeal of the new Sugar Bay Plantation Hotel.
In 1992, permission was sought to replenish the sand on
the beach using 4,000 cu yd of sand purchased from off
island and to place boulders on top of the reef to
simulate the protection previously naturally provided
by the reef. The irony is that one of the original uses
of the dredge spoil was to enhance beaches in the bay.
V-25
Quinn and Kojis
Dredging Consequences
.Monday morning quarterbacking is fun unless you are the
one who must pay for someone else's mistakes.
PATHOLOGICAL EFFECTS ON UibHs
Dredging, filling, and other physical changes to habitats in
the tropics have been implicated in the increased incidence
and outbreaks of ciguatera fish poisoning. The poisoning is
caused by a toxic dinoflagellate, Gambierdiscus toxicus
(single celled plant), growing on macroscopic algae, which
are consumed by herbivorous fish. The herbivores are eaten
by carnivorous fish and the toxin passed up the food chain.
Although mildly toxic to fish, ciguatera is much more toxic
to mammals, including humans. There is considerable circum-
stantial. evidence for a relationship between'ciguatera and
construction' activities. Ciguatera was absent on some
Pacific atolls before construction, but outbreaks occurred
on atolls such as Palmyra, Johnston and Bikini during and
after construction.
RECOMMENDATIONS
Recommendations for alleviating impacts of dredging:
1) Choose an appropriate site. Locate a site with natural
conditions that would minimize impacts. Avoid par-
ticularly valuable or sensitive areas.
2) Test dredge material to determine its composition and if
it is toxic.
3) Select best available appropriate technology (BAAT).' The
selection of BAAT will help minimize turbidity and
sedimentation during both the dredge operation and spoil
dumping. Dredge spoils can often be collected in cascaded
settling ponds and, if not toxic, used for alternative
purposes such as fill or other construction related pur-
pose.
If the dredge spoil is toxic, contact the Department of
Planning and Natural Resources, Division of Environmental
Protection for information on suitable disposal methods.
Physical barriers such as silt screens surrounding the
dredging operation and a combination of silt screens and
earthen berms on the spoil site can be effective in
reducing turbidity. Silt screens are curtains of plastic,
fiberglass, or other fabric that in the water are hung
from the surface using a system of floats and anchors;
normally, silt screens are effective where wave action is
low and water currents are 2 ft/sec or less.
Quinn and Kojis
Dredging Consequences
3) Consider the restoration potential of the site after
dredging and restore the site if possible.
4) Beware of indirect impacts of dredging such as anchoring
operations for barges, ships, and pipelines. Avoid plac-
ing anchors in and dragging them over sensitive ecosys-
tems such as coral reefs and algal / sea grass meadows.
REFERENCES CITED
Dodge, R.E., R.C. Aller and J. Thomson. 1974. Coral growth
related to resuspension of bottom sediments. Nature
247:574-577.
Grigg, D.I. and R.P. vanEepoel. 1970. The status of the
marine environment at Water Bay, St. Thomas. Govt. of
the V.1., Dept. of Health, Division of Environmental
Health. Water Pollution Report. pp. 11.
Kojis, BL & NJ Quinn. 1984. Seasonal and depth variation in
fecundity of AcroDora Dalifera at two reefs in Papua
New Guinea. Coral Reefs 3:165-172.
Maragos, J.E. 1979. Palmyra Atoll: Preliminary Environmental
Survey and Assessment. U.S. Army Corps of Engineers,
Pacific Ocean Division, Honolulu, Hawaii.
Maragos, J.E. 1984. Kosrae airfield and dock project at Okat
(TTPI) and follow-up meeting with Navy OICC, Guam. U.S.
Army Corps of Engineers, Pacific Ocean Division, Hon-
olulu, Hawaii.
Maragos, J.E. 1987. Environmental Impact Assessment Made
Easy. South Pacific Regional Environment Programme.
South Pacific Commission, Noumea, New Caledonia. pp 34.
Maragos, J.E. 1989. Impacts of construction- on coastal
ecosystems in Oceania: A review. Pac. Sci. 33:45-67.
Maragos, J.E., C. Evans, and P. Holthus. 1985. Reef corals
in Kaneohe Bay six years before and after termination
of sewage discharges. Proc. 5th Inter. Coral Reef
Cong., Tahiti. 4:189-194.
Hubbard, D.K., J.D. Stumb and B. Carter. 1987. Sedimentation
and reef development in Hawknest Fish and Reef Bays,
St. John, U.S. Virgin Islands. Biosphere Reserve
Research Report No. 21:199.
Hudson, J.H., E.A. Shinn and D.M. Robbin. 1982. Effects of
offshore oil drilling on Philippine reef corals. Bull.
Mar. Sci. 32:890-908.
V-27
I:
Quinn and Kojis
Dredging Consequences
Rice, S.A. and C.L. Hunter. 1992. Effects of suspended
sediment and burial on scleractinian corals from west
central Florida patch reefs. Bull. Mar. Sci. 51(3):429-
442.
Rogers, C.S. 1990. Responses of coral reefs and reef organ-
isms to sedimentation. Mar. Ecol. Proa. Ser. 62:185-
202.
vanEepoel, R.P. 1969. Effects of dredging in Water Bay, St.
Thomas. Govt. of the V.I., Dept. of Health, Division of
Environmental Health. Water Pollution Report. No. 2,
pp. 10.
vanEepoel, R.P. and D.I. Grigg. 1970. Effects of dredging at
Great Cruz Bay, St. John. DNPi tent of Health, Divi-
sion of'Environmental Health, Water Pollution Report.
pp. 4.
Virgin Islands Marine Advisors. 1992. Environmental Assess-
ment Report. Beach Restoration at Sugar Bay Plantation
Resort. pp. 70.
1 79
F M.AM o a
ImR
by 7 tdi . .
duV gdtgf
Fig urea 1. Adves effct oFdeg n ill fo effAi
runway and dock construction at Okat, Harbor,
Kosrae Island, Federated States of Micronesia
(adapted from U.S. Army Corps of Engineers 1989).
V2
How impacts ane being eliminated:
KANEOHE BAY BEFORE 1938 KANEOHE BAY 1950 KANEOHE BAY 1976 KANEOH-E BAY 1983
A
O AHU OAHU B AH OAHU
0 Aa 9
: -' e
I ':
I a th
Fgr2.Avrefsof drdgng filn ndSwg
discharge in Kaeh aOhu aai(fe
aa o et l. 1985.
Al
iI
OU MCAN
I C
WaWt tricki" IEIqai,&ft tt iew Matte upam owi tet " I *add k anS rnp..d .web
t se.*mi ecosed lagon (after Maao,q199)
tl ihVrulyn eppsstruhtere "n tl itdepwiecanluthrg h 1Zrdrf
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ei-ecoe aon atrMrao,18
V3
PALMYRA 1939 1
Oman
M-Y R A-1 9 4 6- A
NRA ---- -1--Pcii4 O o
Figure 4. Adverse effects of dredge and fill operations'at
Palmyra Atoll, U.S. Line Islands (after Maragos,
1987) .
GREAT CRUZ B3AY
Blasbalg Pt.
Figure 5. Location of 1960's dredge site in Cruz Bay, St.
John, U.S. Virgin Islands
M
St r1. Thms USV
20. .
2 - i.
Dredge hole
Figure 6. Location of dredge site in Water Bay, St. Thomas,
U.S. Virgin Islands (after VIMA, 1992).
V-3
HOW TO PREVENT OR MINIMIZE BEACH EROSION
Dennis K. Hubbard
V.I. Marine Advisors, 5046 Cotton Valley, St. Croix, USVI 00820
Introduction
Beach erosion has become an increasingly prevalent problem in the territory, primarily
for two reasons. First, sea level continues to rise, as it has for the past 18,000 years.
Global warming tied to the increased introduction of carbon dioxide and other
"greenhouse gasses" into the atmosphere may result in dramatic acceleration of sea-level
rise over the coming decades. However, this remains largely a natural phenomenon over
which we have little direct control. Our best response to this is awareness and the careful
siting of development in areas that will be least affected. The other, and more
controllable, factor in increased beach erosion is the accelerating pattern of development
and the mistakes that are too often associated with it. These are the most-easily remedied
and are the focus of the discussion below.
What Causes Beach Erosion
Most-simply stated, erosion occurs when more material leaves an area than is being
delivered to it. While seemingly a simple concept, ignoring this immutable law of nature
lies at the heart of most beach-erosion problems that we face today. The key is, therefore,
to recognize the factors that result in this imbalance and to suggest ways to avoid or
remedy them.
Natural beach erosion is generally occurring to some degree throughout the territory.
This is related in part to the gradual rise in sea level mentioned above and in part to the
natural tendency for waves to break down the materials that comprise our shores and to
move them offshore. Beyond this, mostof the problems that we have seen are related to
somehow interrupting a natural pattern that has in the past resulted in a near balance
between sediment coming in and sediment going out. This usually takes one of two
forms. First, some sort of physical barrier can be placed in the nearshore system that
prevents sand from moving along the beach. The simplest example is a groin (Fig. 1), a
linear structure erected perpendicular to the shoreline. Because waves approach at an
angle, sediment is moved dominantly in one directionalong the shore. In'the Virgin
Islands, this is generally toward the west as a result of the prevailing Trade Winds. A
groin placed across a beach will trap sand along its eastern side because the sediment is
....
Figure 1. Alongshore sediment transport without (A) and with (B) a beach groin present. Once the rock
structure is in place, sediment moving from left to right is trapped by the groin. As a result. the beach on
the left accretes and the one to the right erodes. This is in contrast to the uninterrupted transport without
any structure.
V-35
A- : : I
A ..... ...
emaiiUprush ,ses. Incoming wavediment on the
Backwash for the reflected aveis process continues until the
the resident sediment
Offshoreplaced. Trans Offshore rsortn.
Figure that Waveinduced sediment texsport ona natural beach (A) and against a seawad (B). On the
sloping beach, the uprush and backwash have roughly equal tansport potential. As a result, the beach
protection stable until a storm passes. In const, waves reflecting off the seawall stir up sediment on theline,
way in, leaving it in suspension for the reflected wave to move it offshore. This process continues until the
nearshore zone fronting the wall is scoured to a depth w hen waves can no longer effectively suspend
the resident sediment.
coaming in naturally from the east, but cannot get past the groin and move out to the west.
On the other side of the structure, sand is being moved away to the west, but is not being
replaced. The result is erosion.
The second common cause of beach erosion involves modifying natural processes in a
manner that favors net sediment export. One of the most commonly used coastal-
protection structures is the seawall. This structure armors a stretch of eroding shoreline,
creating security for the properties immediately behind it. The problems with these
ubiquitous features are many, however. The most problematic is scour. When wavesach.
encounter a vertical or steeply sloping surface, they reflect seaward. The reflected wave in
carries with it large quantities of sediment, resulting in erosion along the base and ends of
the wall, sometimes undercutting the structure to the point of collapse.
To understand the nature of this complex interaction,. let us consider what happens to a
wave as it runs up a natural beach, and contrast that to the same waves breakinc against a
vertical seawall. On a beach, the wave gradually breaks as it moves into shallower water.
In the process, sediment is picked up from the bottom and moved onto the asbeach face. As
the uprush of the wave slows, sand is deposited on the beach. As the wave swash satops
on the beach face and runs back to the sea, some of the water is absorbed into the beach.
As a result, not as much water moves seaward, and the return swash is less effective inot provide
picking up and removing the sediment that was just deposited - thus, the beach accretes.
all of its energy tohe slope the beach adjusts tom the shpoint that landward and seaward
transport balance one another and the beach stabilizes.
On a shoreline "protected" by a seawall, the sequence of a strong wave -uprush. deposition
of sand on the beach and a gentler backwash is modified. Consider. as an analogs'. a ball
striking the cushion of a billiard table. It will come off the cushion with nearlv the same
speed it entered. The same thing happens along a seawall. We must add to this scenario
the facts that 1) the incoming wave has already done all the work of suspending the
nearshore sediment and 2) the quick reflection of the wave off the wall does not provide
an opportunity for the sediment to settle out. Therefore, the reflected wave is free to use
all of its energy to move that sand away from the shore. In combination with the
turbulence that is generated around the base of the wall, the net result is severe erosion
that will lower the substrate to a depth below which the incoming waves axe no longer
j efficient in suspending sediment.
These are offered only as simple examples for the sake of illustration. Accretion to the
east of a groin and erosion to the west should not be taken as a hard and fast rule. Our
coastline is very jagged, and waves can be bent and redirected such, that a very complex
transport pattern results. Likewise, a seawall should not alway's be ruled out as a
defensive structure. Sometimes, the need for shoreline stabilization is so eminent that a
wall is the only realistic option. Also, there are strategies that can mitigate the effects
discussed above (for example, placing the seawall on a solid, rocky substrate). In both
instances, the answer lies in careful consideration of the existing natural forces and the
changes that are likely to result from the use of a particular structure. A careful analysis
of the nearshore wave field under both day-to-day and storm conditions should be
completed before considering any coastal modification.
What Can We Do About Erosion?
Providing examples of every type of erosion problem and solutions to each are far
beyond the scope of this short paper. In the Workcshop, case histories have been provided
that illustrate the lands of problems that most commonly occur and the solutions that
worked under that particular set of circumstances. As a general point of reference, we
have assembled Table I which briefly outlines the types of erosion problems that are
most common in the U.S. Virgin Islands, the processes that are involved and possible
remedies for them. Beyond that, the best advice that we can offer is to consult with a
trained professional before attempting even what may appear to you as a benign
modification. I was recently asked to comment on possible causes of and remedies for a
new and sudden episode 'of beach erosion on St. Croix. After examining the beach, I
suggested a program of aggressive beach revegetation. I was summarily informed that
the owner had just spent considerable effort and money to pull up the existing vegetation
as the owners of the property wanted an open, sandy beach and not a lawn - my solution
was clearly not acceptable to them. This kind of ignorant practice, more than any other.
has traditionally lead to the problems that we now face. The laws of physics are the only
ones that we cannot break without sure punishment.
* Beach Nourishment as an Option
From the introductory discussion of erosion as an imbalance between sediment coming in
and going out, we can deduce that erosion on a particular beach is necessarily being offset
by accretion some-where else. Corollary to this idea, any engineering measure that causes
sand to be deposited on your beach necessarily robs another site. As a result, the only
way that you can circumvent this relationship (but still only on a local basis) is to bring in
sand from an outside source - beach nourishment.
While preferable to most complex engineering solutions, there is a downside to this
approach. First, it is expensive. Sand from off-island costs in the vicinity of $35 a yard.
Therefore, even a modest nourishment project of 500 cubic yards will cost $17,500 for
the sand along. To this, you must add handlirng costs, permnitting fees and the studies that
are necessary to obtain those permits. From a philosophic point of view, you are still
robbing sand from somewhere else to solve your problem. And finally, you are probably
committing to a long-term program of successive renourishment.
V-37
Table 1. Common beach-erosion problems and their remedies.
Cause of Erosion Factors Involved Remedy '
Sea-Level Rise Natural forcing functions; Stay out of its way, build with
Global Wanrmin common sense
Seawall Scour at the base of the wal; Foot seawall in rock
Preferential seaward transport Foot seawall deep enough to prevent
of sediment undercutting
Design wall to minimize scour
Breakwater Reduces transport along the shore that Use only in areas where downdrift
is protected by the structure; can shoreline is rocky (i.e.,
cause erosion downdrift not subiect to erosion)
Groin Block alongshore transport Use only in areas where downdrift
beach is not sensitive (e.g., rocky
or no develonmentf
Vegetation Removal Destabilization of the substrate, Don't do it; in areas where erosion is
making it more susceptible to already a problem, undertake an
erosion aggressive revevetation rnream
Offshore Dredging Creation of a hole that Mother Nature Avoid nearshore dredging
wants to fill. If it is close enough,
your beach will provide the fill
Modification of offshore wave patterns
that become focused on vour beach
Destruction of offshore reefs Removal of protection from waves Ensure that your project does not
cause damage. If the problem
already exists, then protection
must be re-established.
Aside from the more altruistic aspects of the decision-making process (e.g., finding a
supply that has not caused environmental damage at that locale), there are several
important considerations in designing a working nourishment program. First, the sand
must be of a proper size that it will remain on the beach. As a rough rule of thumb, do
not put anything on the beach that is finer than what Mother Nature left there. The reason
that the existing sand is there is that ambient waves could not pick the material up and
move it away. Anything finer will disappear quickly. There are simple engineering tests
that can be performed to approximate the fate of your chosen sand. Ambient wave and
current conditions also need to be understood. This is important from a standpoint of
understanding where your sand might go under extreme conditions and- what adverse
environmental impacts it might have. Consider, for example, that seagrass tends to
stabilize the sand in the immediate offshore zone of many island beaches. Extreme levels
of sedimentation can bury those grasses, thereby removing their stabilizing effect and
opening your beach to increased erosion. Offshore reefs that now provide protection for
your beach, if killed, will quickly be "eaten away" by the countless organisms that live on
the reef and grind away at dead substrate to make their living in the reef economy. As a
result, your beach will be exposed to increasing wave attack and will erode at an even
greater rate.
This discussion closes with two points. First, beach erosion is not necessarily a bad
thing. It is part of the natural waxing and waning of any shoreline comprised of loose
material. The problem arises only when a man-made structure is put in the way of this
process. A beach may come and go as part of the natural cycle. The end result is a stable
beach over a long period of time. However, a building or other structure that is built on
the beach and destroyed during the erosive cycle will not repair itself when the beach
comes back. Erosion is not the problem: man-made structures put in its path are what we
V -38
are trying to avoid. Second, it cannot be stressed enough that a "qualified marine
professional" is not just someone with an advanced degree whose business brings them in
contact with the sea on a regular basis. Biologists have special talents that qualify them
to address ecosystem-level effects. Coastal engineers have. been trained to design
structures that will withstand the physical impact of wave attack. And marine geologists
generally focus on physical-oceanographic phenomena and their effects on coastlines and
the sediments that make them up. Expertise in one of these areas does not necessarily
qualify them to make informed judgments about everything that goes on in the marine
environment. Choose your "experts" wisely.
V-39
VI
AGRICULTURE AND WETLANDS
Overview of Agricultral Nonpoint Source Pollution
Olasee Davis ................................................ VI-1
How to Manage Wastewater and Runoff from Confined Animal
Facilities
Jeff Schmidt . . ...................................... VI-9
The Benefits of Using Sustainable Agriculture
Louis Petersen . . ..................................... VI-12
The Environmental and Economic Benefits of Wetlands
-- Algem Petersen . . ..................... ..................... VI-15
Using Artificial Wetlands for Pollutant Removal
Carlos Padin ..................................................
PaenoavIlal :tieoprnng
* Paper not available at time of printing.
Il0, ' 0 X ' 0-f 0 , :: f ; | V jf ;
OVERVIEW OF AGRICULTURAL NONPOINT SOURCE POLLUTION
IN THE U. S. VIRGIN ISLANDS
Olasee K. Davis
Cooperative Extension Service/Natural Resources, University
ofthe Virgin Islands, Kingshill, St. Croix V. I. 00850
HISTORICAL REVIEW OF AGRICULTURE IN THE U. S. VIRGIN ISLANDS
At one time, the Virgin islands had an extensive and
luxuriant forest. During the virgin stage of these islands,
the native Indians gathered wild fruits from forest and
cultivated small plots of land. Land plots, however, did very
little to alter the forest ecosystem.
By the arrival of Columbus in 1492, forest was still the
dominant vegetation throughout the islands, with the possible
exception of a few small wetlands and rivers. Between the
15th and 16th century, a drastic change took place by the
European settlers that inhabited the Virgin Islands.
Large acreage of forest lands were burned for colonial
agriculture development on St. Croix, thus changing the
ecology of the island. Also, clearing of land on St. Thomas
* and St. John went through a similar phase for agriculture
development.
Land clearing was made possible when African slaves were
brought to the shores of these islands in the late 1600's.
Slaves cleared the land by cutting the trees and setting them
on fire. At this period, sugarcane plantations were
estblihedfor agriculture production'. By the mid-1800's,
the island of St. Croix had 114 windmills and 144 animal or ox
* mills.
In the early 17th century, agriculture revolutionized the
islands' economy. With this, soil erosion became a major
factor in agriculture production. Plantation crops were
planted on slopes and hillsides, causing considerable erosion
of the already thin tropical soil. Furthermore, the repeated
burning of crop residue degraded the soil further by
destroying its structure and reducing its fertility.
At this time, the European settlers realized that in
order to continue to make a profit from the land, they would
U have to implement conservation practices. As a result, St.
Croix's rolling hills were plowed along the natural lines of
the land to keep the soil from washing away, while on St.
Thomas and St. John, terraces were built along the hillsides
to reduce further soil erosion.
v1-1
Techniques in land use, combined with engineering and
management practices, were thoroughly developed and well known
in ancient times before the first Europeans set foot in these
islands.
Today, it is proven through both scientific tests and the
experiences of millions of farmers in many parts of the world,
that contour practices, designed to fit the topography of theI
land and combined with soil-saving rotation planting and
proper fertilization, provide protection to the soil, conserve
water for plant growth, and raise yields of cultivated crops
in many parts of the world.
Between the 1780's and 18001s, St. Croix became the
richest sugarcane island in the Caribbean in addition to
Indigo, tobacco, and cotton. The 375 plantations on St. Croix
flourished as produce was
exported to Europe. It was at this time that the island wasI
called the "Garden of Eden or Bread Basket of the Caribbean."
However, the prosperity of agriculture production in the
Danish Virgin Islands lasted only for a short time.
After more than 200 years in which the ownership of the
Virgin Islands changed several times, Denmark encountered
serious problems. Problems occurred when St. Croix wasI
controlled by the British for a brief period of time. In
1803, the slave trade was abolished. Other problems arose
when natural disasters such as earthquakes, tidal waves,I
hurricanes, droughts, and political upheavals and war-, in
Europe worsened the Virgin Islands economy. By 1848, he
slaves received their physical emancipation.
A few years later, in 1917, the United States purchased
the Virgin Islands from Denmark. Since then, the agriculture
industry in the Virgin Islands changed drastically. Prior to
the emancipation of the slaves in 1848, the island of St.
Croix was cultivated from the beaches to the hilltops. There
were some 30,000 acres of farmland devoted to sugar cane andI
other important crops.
Back then, sugar commanded up to $2.00 per pound in the3
world's markets, and under these circumstances the one crop
economy was profitable. In 1966, sugarcane production phased
out in the Virgin Islands and agriculture shifted from
cropping to livestock production. Today, dairy and beef
cattle are the Virgin Islands' two largest agricultural
industries, primarily located on St. Croix-.
THE EFFECT OF NONPOINT SOURCE POLLUTION ON AGRICULTURAL LAND
In agricultural areas of the U. S. Virgin Islands, the
major nonpoint source pollution are land clearing,
sedimentation, overgrazing, and to some extent the misuse of
pesticides and fertilizers.
VI -2
LAND CLEARING
Of the earth's land surface, 43 percent is Occupied by
rangeland, 11 percent by farming, 31 percent by commercial
forest, and 15 percent by ice. ..in the Virgin Islands,
approximately 75 percent of the agricultural land is devoted
to animal husbandry with St. Croix having 92 percent of the
grazing land.
The majority of this land, however, is covered with
shrubs and bushes which reduce the productivity of animal
production. Poor pasture management leads to undesirable
species such as Casha (Acacia spp.), which dominates most of
the Virgin Islands pastureland.
Thus, farmers find it necessary to clear the land in
order to Aincrease forage production for animal consumption.
Oftentimes, however, lands are indiscriminately cleared by
removing desirable plants with topsoil leaving the land bare,
which is probably the worst thing that can be done.
It is important to leave vegetative cover on the land in
order to protect the topsoil. The energy of failing raindrops
is expended directly on the soil surface when land is cleared
of every vegetation. During rain, the soil surface seal forms
quickly and soon water run of f at a maximum rate.
SOLUTIONS FOR CLEARING LAND
3 1 . Avoid clearing land during the rainy season.
2. Leave trash on the land to reduce soil erosion.
3. Maintain as much permanent-type grazing grass as
possible.
4. Plan and follow a weed control program.
5. Follow recommendations closely in establishing
pasture (Experiment Station scientists and
Cooperative Extension Service Specialists will
provide recommendations when needed).
SEDIMENTATION
Sediment is made up of tiny soil particles that are
washed or blown into guts, streams, eventually- end up in the
sea. Sediment Is also one of the most damaging pollutants on
agricultural land in the Virgin Islands, and nonpoint source
pollution. Loss of soil by washing and blowing usually
follows deterioration of vegetation. As soil becomes less
abundant and increasingly compacted with misuse of the land,
decreased water infiltration and increased runoff are
inevitable.
VI- 3
On many pasturelands in the Virgin Islands, especially
slopes and grazing land near the coast, gully erosion IsI
visible. It occurs, either where runoff from a slope increase
sufficiently in volume or.velocity to cut deep incisions, or
where the concentrated water flows long enough in the sameI
channel to develop deep incisions in the soil.
Often gullies develop in natural depressions of the land
surface where run-off water accumulates over a period of time.
Gullies are often started by ruts or tracks up and down hills
by the movement of machinery or livestock. With gullies,
sediment is carried or transported picking up soil particlesI
and disposing it in farm ponds or along the coastlines.
Although these problems are visible and easy to
understand, other nonpoint source pollution problems
associated with sediment are less obvious. For example,
nutrients and pesticides can become strongly bound toI
sediment, especially fine soil particles, and can be carried
with it to surface and ground water. These pollution sources
will be discussed later.
SOLUTION FOR SEDIMENTATION
1. Control erosion with vegetation cover.
2. Livestock distribution on pasture land.
3. Ponds or dams construction on pastureland.
4. Practice conservation measures.I
OVERGRAZED PASTURELAND
The primary purpose of pasture management is to prevent
excessive grazing. This is especially important during the
growing season for livestock farming in the Virgin Islands inI
order to increase the vigor and productivity of existing
forage plants and eventually,' to improve species composition.
Animals have a major impact on the physical environment andI
the plant communities in which they are associated with
(Davis, 1993).
This impact is also influenced by climate changes, land
topography, and soil type which determine species of plants
adaptation to different areas of the islands. Since most
pastureland are made up of complex plant species, grazing mustI
consider availability and palatability of the vegetation to
maintain healthy animals.
Animals will not graze all individual plant species
uniformly unless the pasture is overgrazed or graz ing is
carefully controlled to maintain plant vigor throughout theI
growing season. Also, with a given site, different plant
species will maximize their growth at different times of the
year.
VI-4
As plant community develops, there is a continual change
in the relative proportions of different plant and, therefore,
a continually changing availability of forages (Mott 1960).
If grazing is unmanaged or managed without consideration of
the dynamic nature of the plant ecosystem, some forages will
be grazed heavily by animals while others are lightly grazed
or not grazed at all during the growing season.
This has been the case for years in most pastureland in
the Virgin Islands. Desirable forages such as guinea grass
(Panicum maximum) are at a disadvantage because of
differential grazing will lose to the more undesirable plants.
This will change, and usually reduce, the productivity of
pastureland.
Thus., many pastures in the islands are overgrazed and
invaded by plants that affect the performance of animals
nutritionally to produce beef or milk. Such undesirable
pasture plants as (Crotalaria retusa L.), Maran (Croton
riaidus), and Wild physicnut (Jatropha gossypifolia L.) are
indicators of overgrazed pasture land.
Overgrazing of pastureland in the Virgin islands has a
major impact on land thus contributing to some level of
nonpoint source pollution to surface or ground water supplies.
Livestock affect watershed properties by removal of vegetation
cover and through the physical action of their hooves.
Reduction in vegetation cover of pasture can increase the
impact of raindrops, decrease soil organic matter, soil
aggregates, and increase soil crusts.
The primary effect of hoof action is the compaction of
the soil surface. As a result, it decreases water
infiltration rates, increases runoff, and soil erosion.
Livestock also affect water quality. Fecal wastes from
livestock grazing can be a sizable pollution problem in range
watershed management (Holecheck, Pieper, and Herbel 1989).
To avoid such problem is to control the number of
livestock, distribution in pastures, and attract livestock
away from guts or stream areas. Grazing systems can help
improve livestock distribution, and pasture forage conditions
by protecting plant during critical growth periods, and can
improve livestock performance by ensuring that plants are
utilized at the best times of the growing season. The chart
below shows one of many grazing systems that can be used
locally for livestock production.
VI-5
Four-Pasture Merrill System
A_. My _ m - iN v . -m m,
A n A a A
pr i -ow.1 -
ns'r ..,G y G _ Gra. Rag G.ae
maintain goodpastureland.
D C C c
Limslo& concenhis on most wnuitional plants vAen fint placd in afrespastur Men
there plants are grazed they then graze ess nutritional plants: thus. the nztritional level of
their diet goes down. To overcome, speed up mom.
GRAZING SOLUTIONS
1. Implement grazing systems that will create and/or
maintain good pastureland.
2. Control of space or how much area is to be grazed.I
This is done with fences, either permanent or
temporary.
3. Control of time. How long the area is to be grazed
v
or rested.
4. Control of numbers, or how many animals are to be
placed in the area to be grazed.
5. Control of the animal. The farmer must be able to
place the animal where and when he wants, for as
long as he wants.
PESTICIDES
"Pesticide" is an umbrella term that covers a wide range of
chemicals such as insecticides, fungicides, and herbicides.
The use of these agrichemicals help the Virgin Islands farmers
to produce high yields of crop, but pesticides could also
provide a pathway for toxic pollutants to our ground water if
they are used incorrectly.
Proper applicationtro of pesticide and operation of equipment are
important to protect the applicator as well as the
environment. The prevention of nonpoint source pollution by
pesticide concentrates, spray mixtures, or wastes is also
essential in protecting the environment.
VI-6
At this moment, pesticide is not a major environmental problem
as a nonpoint source pollution. Most Virgin Island farmers
practice sustainable agriculture. However, the potential for
pesticides to become a serious environmental problem is there.
Those who use pesticides need to understand the chemical
properties and how they should be applied in order to protect
* our natural resources.
The University of the Virgin Islands Cooperative Extension
Service conducts classes both in the private and commercial
category for pesticide applicators who want to become
certified. By using pesticides wisely and applying them
correctly, the responsible pesticide applicator can use these
chemical for the benefit of the environment.
FERTILIZER
As crops-grow, soil nutrients are utilized to produce food.
on the other hand, significant amounts of nutrients are
removed from the soil when crops are harvested and not
recycled back to the soil. Thus, nutrients such as nitrogen,
phosphorus, and potassium are essential parts of the
agriculture industry in the Islands. These nutrients may be
added to the soil in the form of fertilizer, decaying
vegetation, or manure.
Fertilizer is not a major nonpoint source pollution in the
Virgin Islands agriculture industry. But every step should be
taken by farmers not. to misuse fertilizer on farmland. All
form of nutrients such as manure, legumes, and fertilizer
should be managed properly to meet the needs of crop nutrients
and reduce the chance of nutrient loss to surface or ground
* water.
CONCLUSIONS
The risk of agricultural nonpoint source pollution can be
significantly reduced by more prudent application of land
clearing, overgrazing, nutrient, pesticide and by good overall
land management. I personally believe that conservation
practices of agriculture provide environmentally and
economically sound farming techniques for the Virgin islands
farmers. Finding solutions to environmental pollution can
only be solved when we recognize the .importance of managing
our natural resources properly.
VI-7
I l
REFERENCES
Jerry, L., Holecheck, Rex., D. Pieper and Carlton., H. Herbel.
1989. Range Management Principles and Practices.
Mott, G. 0. 1960. Grazing Pressure and Measurement of
Pasture Production. Proceedings of the 8th International I
Grassland Congress, pp. 606-611.
Davis, K. 0. 1993. Range Ecology. Virgin Islands
Agriculture and Fair 1993. VI Dept. of Economic Development
and University of the Virgin Islands. Bulletin Number 7 pp.
23-24.
I--
VI-8
- '; Rg0. 0 I
f + * r ; 0 | ti 8
HOW TO MANAGE WASTEWATER AND RUNOFF FROM
CONFINED ANIMAL FACILITIES
JEFFREY J. SCHMIDT
United States Department of Agriculture
Sail Conservation Service
United States Virgin Islands Field Office
St. Croix, USVI 00851
The United States Virgin Islands confined animal facilities are
very unique. Two categories are the most common and at the same time
veydifferent. In one category, there are less than a few dozen farms
that have large enough systems (usually more than 75 head of stock) that
would support controls or measures that are engineered, designed, and
I I constructed, but may require large sums of monetary support. Most
commonly these herds are either dairy, beef, swine, sheep, goats, or
poultry. This is not to say that all large facilities have water
quality problems, but rather the potential is greater.
On the other hand is the category where there are virtually
hundreds of small operations of confined animals. The animals common in
this group are more of a mix than the preceding category. Again, each
situation is different. Five goats can be more hazardous than twenty
cows if the confinement location is not appropriate.
Of course there are the herds that just roam, graze, or browse.
Common to this group are horses and goats. It should be noted that any
animal can be a roamer, should gates be left open or fences be in dire
need of repair. Certain animal types are common to an area in the
VirinIslands, rather than the rule. In other words, these
domesticated animals do not roam from coast to coast in search of food
or forage. But rather stay in an area big enough to support the herd,
9 and from there they do not venture. Commonly referred to as the lands
"carrying capacity". This refers more directly to the plants ability to
survive grazing pressure. These roamers can also be detrimental to
humans, other livestock herds, and to themselves as well. It just
9 depends on where the feces fall.
Wastewater management problems often arise when livestock are
added to a farm without increasing the land base. When land and animals
are out of balance - that is the waste produced greatly exceeds the
capacity of the land to utilize the nutrients in the waste product - we
find that water quality problems begin to show. Unfortunately, these
problems can go unnoticed for a long period of time. Some examples
pcould be fish kills, odor, drinking water contamination, or even
bacteria related diseases spreading to humans. A commnon bacteria in
these cases is E-Coli.
Careful observation and common sense can often determine whether a
given farm practice is likely to cause the quality of water to
deteriorate or affect the environment. The quality of water can be
adversely affected if manure runs into streams or guts as a result of
land application, spillage, storage overflow, or deliberate dumping.
VI-9
Increased bacterial counts can indicate this has happened. Several
illnesses can be attributed to high bacteria counts in water systems.
Common are typhoid, hepatitis, bronchitis, and even urinary infections.
All of which can be fatal if not treated. More often than not, rainfall
transports the waste products into the groundwater and/or across the
soil surf ace. Nutrients in manure applied to the soil at rates that I
exceed the soils and plants ability to breakdown or uptake the
nutrients, can leach into groundwater or be carried away of f site with I
runof f water. and eroded soil to the sea. This off site transport- is
often referred to as non point source pollution. Increased' nutrients
like nitrogen in the groundwater can cause drinking water problems for
water well users. Nitrate poisoning is possible which can be serious,
but more so to infants.
The reasons for developing and maintaining a sound wastewater
management plan include: 1) environmental benefits to everyone, 2)
economic benefits to the farmer, and 3) compliance with laws and I
regulations concerning environmental quality.
Let us explore managing waste from a large animal facility first
so that we can be introduced to the general principles of waste i
management or runoff control. The two are rather synonymous.A
component of waste management is controlling runoff to and from the
confined facility.
A system to manage waste and runoff from a confined animal
facility must be developed using a total systems approach. A total
system accounts for all the waste associated with an agricultural
enterprise throughout the year from production to utilization. From
extra feed to overflowing watering tanks. From parlor flushing to
excess bedding. From manure storage to application. Everything. In
short, it is the management of all the waste, all the time, all the way
through.
With this in mind we begin the process of inventorying all of the
resources associated with the agricultural enterprise. This list is not
all inclusive. The accuracy of identifying the resources allows more
functional alternatives to be developed. Some of the data you collect
can be easily measured, such as the number of acres available to spread
waste. While other data may be less tangible, not easily measured, but
rather rely on personal discussions, observations, or just. plain common
sense judgement.
A brief list of the inventory needed includes: type of livestock,
type of operation, breed, size (number of stock, ages, weights,
replacements), feeding components, site location, bedding, present
facility, land availability, soils, topography, rainfall, geology,
crops, labor availability, equipment availability, 'level of producer
management, adjacent land use, livestock travel routes, confinement
days, laws and regulations, utilities, landscape resources, flexibility,I
expansion opportunities, producer financial situation, etc, etc.
Once a thorough investigation of the resources is complete,
arrange the information into six categories for interpretation,
analyzation, and evaluation. They are: 1) Production, 2) collection, 3)
Storage, 4) Treatment, 5) Transfer, and 6) Utilization. Once broken
down into one or more of these categories, alternatives can be selected
that best fit the site conditions, livestock operation, and theI
producers objectives. When selecting and considering alternatives,
VI-lo
always keep in mind that the purpose of managing animal wastewater is
not to detrimentally affect water quality or the environment.
ii Components Of the previously mentioned categories are more
commonly known as "alternatives available to manage wastewater and
runoff". They include, but again are not limited to.- roof gutters,
ii clean water diversions, dirty water diversions, alley scrapers, flush
alleys, ponds, tanks, dry stack, lagoons, composters, solid separators,
settling basins, pipelines, hauling equipment, pumps, push off ramps,
ii irrigation systems, spreaders, commercial sale, refeeding, bedding,
energy generation, artificial wetland wastewater treatment, etc, etc.
This last alternative is excitingly new for the Virgin Islands and may
hold great promise because of our shrinking agricultural land base.
Movin to a smaller operation, all the principles of planning and
daacollection are the same, you just do not have the land base
avalaleand move common, the financial capital to build the same
ii controls as. a larger operation. some items are suggested for larger
operations 'an well. These happen to be virtually free from monetary
input. The first thing that can be done is to reduce the stock size.
II Prevent stock from entering watering facilities, streams, ponds., and
diversions, rotate pastures, rearrange feeding areas away from steep
slopes, create buffer strips, repair fencing, feed in bunks not on
p ground, and keep thinking. Common sense approaches can be found every
day. Your only limitation sometimes can be your imagination. Animal
waste management is not a one day event. Conditions are constantly
changing, as you must, in any farming or animal management enterprise.
Managing wastewater and runoff from confined animal facilities is
dynamic with many alternatives being available as well as many problems
p hat can be created. Because of the variety of alternatives, solutions,
conditions, and situations, that the management system must be
incorporated, no one procedure can be followed to arrive at a one system
design. One recommendation may be ideal for one farm and completely
9 inappropriate for another. Alternatives are always available. Whether
they are the ones that fit your operation, or are feasible for you, may
be a completely different matter.
In conclusion, the most important item is to recognize a problem,
even a potential problem, and to take positive steps *to protect,
restore, and improve the environment - specifically the quatity of water
in this case. Out of sight is not out of mind. Remember, to look in
your own backyard before you criticize across the fence.
VI-II1
SUSTAINABLE AGRICULTURE IN THE VIRGIN ISLANDS I
LOUiS Petersen, Ph.D
CooPerative Extension Service, University of the Virgin I
islands, St. Thomas, VI 00802
According to the Food, Agriculture, Conservation and Trade Act
of 1990, Sustainable Agriculture is an integrated system of
plant and animal production practices having a site-specific
application that will, over the long-term, satisfy human food
and fiber needs; enhance environmental quality and the natural
resource base upon which the agricultural economy depends;
make the most ef ficient use of non- renewable resources and on-
farm/ranch resources and-integrate, where appropriate, natural I
biological cycles and controls; sustain the economic viability
of farm/ranch bperations; and enhance the quality of life for
farmers/ranchers and society as a whole.
Simply stated, sustainable agriculture refers to agricultural
systems that are designed to be productive while being
ecologically sound, economically viable, socially just andm
humane. These systems are comprised of practices such as
composting, inter-cropping, multiple cropping, crop rotation,
terracing, diligent record keeping, appropriate varietalm
selection, and the use of drip irrigation. while some of these
methods and technologies. are new to some farmers and home
gardeners in the Virgin Islands, some have long been in use as
a consequence of tradition or necessity.
Terracing ref ers to the construction of earth embankments,
channels, or combinations of both across the slope of the
land. This has been practiced f or hundreds of years in the
Virgin Islands, especially on St. Thomas and St. John where
the terrain is hilly and often very steep. The most common
type of terrace constructed by local farmers employs the use
of rocks to contain and stabilize the soil. This makes good
use of the many, available rocks which characterize our'soils.
Terracing serves to reduce soil erosion and runoff as well as
create a more manageable working area for the farmer since the
area is made to be level.
Another practice which helps to conserve our natural resources
is mulching. This involves the use of synthetic or organic
materials such as straw, grass cuttings, leaves, manure, woodI
chips, plastic or woven fabric to cover the ground surface
around plants to conserve soil moisture and control the growth
of weeds. Mulched plants need water less frequently than non - I
mulched plants. Mulching also reduces runoff and soil erosion
since the materials used provide a protective covering for the
soil. organic materials such as manure and grass cuttings areI
more commonly used in the Virgin Islands compared to synthetic
ones. Organic mulch materials gradually decompose and enhance
VI -121
iisoil structure and fertility. On the other hand, synthetic
options such as plastic are more durable and can last from one
planting season to the next. Biodegradable plastics have been
ii developed and have great potential usage for Virgin Island
farmers who avoid the use of conventional grades of plastic.
The importance of proper varietal selection of crop types is
*often underestimated by farmers and home gardeners in the
Virgin Islands. By choosing the appropriate varieties of
ftuits or vegetables in production systems, 'lower inputs' of
jI* pesticides, fertilizers, and even water may be necessary.
Modern varieties which are tolerant to diseases, insects,
existing soil conditions, and drought should be used whenever
available.
Crop rotation refers to a system of planting crops in a
ii compatibl e and complementary manner in order to prevent the
potential build up pest populations on a given farm site. It
is well known that the potential for disease and insect
II problems (especially soil - borne problems) increases when the
same or similar crops are grown successively on the same
field. Crop rotation relies on the diversity between plant
types to interfere with the natural life cycle of insects
p and disease causing organisms. Consequently, the quantities of
pesticides used for crop production can potentially be
reduced, and therefore, their environmental impact. In
p addition, when the same or similar crops are repeatedly grown
on the same plot of land, soil fertility levels decline due to
the constant demand for the same quality and quantity of
p nutrients. This usually leads to unnecessary applications of
fertilizer to restore soil fertility. Crop rotation uses
plants which are appreciably different so that soil nutrient
reserves are not exhausted, resulting in "tired soils".
Similarly, the practice of inter - cropping is based on the
principle that similar plant types -attract similar pest
problems while a diversified population of plants guards
against this. Hence, inter - cropping involves the growing of
two or more totally different species together in the same
field. As with crop rotation, to reduce the potential of a
pest outbreak is to reduce the potential environmental impact
of pesticides. Practically all farmers and home gardeners in
the Virgin Islands traditionally practice inter - cropping due
to the unavailability of another very'limited and expensive
resource - - land. Farmers and gardeners must use their land
prudently in order to get as much production as possible from
small acreages.
Another important practice which needs more attention on the
part of Virgin Island farmers is record keeping. Good record
keeping (in conjunction with soil testing) can help farmers
decide if, for example, a fertilizer application is necessary.
Fertilizer applications are often made at random without
witoutconsidering the date of the last application or
3 VI-1 3
the current fertility status of the plot in question. this can
result in unnecessary applications of f ertilizers which, in
turn, can eventually contaminate our aquifers. A good record I
keeping system also documents a crop history (i.e. the
sequence in which crops have been planted on a farm site).
Such information can f acilitate an ef fective crop rotation
system which, as was mentioned previously, is a pest control
measure and which prevents the exhaustion of soil- reserves.
Fresh water is quantitatively a very limited natural. resource I
in the V irgin islands. Therefore, measures must be taken to
make the most efficient use of this precious commodity. Many
producers in the Virgin Islands still supply water to their I
crops by means of the "conventional" hose or a bucket. Besides
causing mechanical damage to plants, this system makes
wasteful and inefficient usage of water. Most of the applied I
water never reaches the plants for which it was intended, and
instead contributes to runoff, erosion and sedimentation of
soil particles. On the other hand, drip irrigation technology I
is strongly advocated for use in crop production since water
use ef ficiency is maximized. This is accomplished by gradually
supplying plants with small amounts of water in a dripping
manner through tubes for periods of time. This ensures maximum
uptake and utilization of the water by plants, and there is no
resultant runoff, soil erosion, or sedimentation. The use of
drip irrigation systems as a production practice is gradually
becoming more commonplace among Virgin Island farmers.
Composting is the practice of managing the decomposition of
organic matter such as plant or animal residue or waste which
results in a rich, humus material which can be used as a
fertilizer, mulch or to improve soil structure; Composting,
therefore, represents a means of recycling the otherwise
refuse by-products of agricultural activity and re-
incorporating these organic materials .into continued
agricultural production systems. The concept of a properly
managed, scientific system of organic matter decomposition is
relatively new to crop producers in the Virgin Islands', but
should be strongly encouraged.
Although the examples given herein are from the perspective of
crop production, sustainable agriculture is also practiced in
livestock production. For example, poor record keeping in
pasture management can result in overgrazing, and thus, poor
management of animal manure, and soil erosion.I
Sustainable agriculture represents one of many initiatives to
address the issue of environmental preservation. with the
assistance of the agricultural agencies of the Virgin islands,I
our farmers can also make significant contributions toward the
conservation of our natural resources in order to ensure
tomorrow's food production.
VI-14I
THE ENVIRONMENTAL AND ECONOMICAL BENEFITS OF WETLANDS
ii AlgeM Petersen
Department of Planning and Natural Resources, Coastal Zone
ii Management Program, St. Thomas, U.S.V.I.
In the ecologist's language, wetlands are known. as ecotones,
or transitional areas - sandwiched between permanently flooded
deepwater environments and well-drained uplands - at one edge
they are predominately aquatic (very wet) and at the other
ii mostly dry (1).
Section 404 of the Clear water Act defines wetlands as
"areas that are inundated or saturated by surface or ground
water at a frequency and duration sufficient to support, and
that under normal circumstances do support, a prevalence of
vegetation typically adapted for life in saturated soil
conditions" (2).
Normal circumstances are considered to be:
0 1. The soil and hydrological conditions that would
exist if the vegetation were not altered or
* removed.
2. Cropping or cropping history is not the normal
circumstances.
p In the recent press release from The White House office on
Environmental Policy, on 'New Federal Wetland Policy,, Carol
Browner, Administrator of the U.S. Environmental Protection
p Agency, states that "American wetlands are currently being
lost at a rate of nearly 300,000 acres per year". Another
section of that release entiled -"Protecting America's
Wetlands: A Fair, Flexible and Effective Approach" further
states "The Nation has lost nearly half of the wetland acreage
that existed in the lower 48 States prior to European
settlement. The Nation's wetlands continue to be lost ata
rate of hundreds of thousands of acres per year due to both
human activity and natural processes. This continued loss
occurs at great cost to society" (3).
During the last thirty years researchers have discovered the
significant, irreplaceable ecological values and roles that
wetlands provide to communities. The term heritage value has
been used to describe the importance of wetlands as
educational resources, as repositories of biodiversity, as
sources of aesthetic experience, and as, simply existing
natural phenomenon. The importance of the goods that wetlands
produce has been extensively documented.
* VI- 15
ENVIRONMENTAL BENEFITS
Wetlands are considered among the most important ecosystems on
the earth. They provide a number of benefits including
nonpoint pollution control. Some of the roles of wetlands
Ainvolve:
Flood Control:
They help to moderate - to control - extreme floods by
absorbing water during heavy rainfall, then slowly releasing I
Erosion Control I
Wetlands buffer shorelands against erosion. Wetland plants
also bind soil with their roots and help to absorb impacts I
from wave action.
Fish & Wildlife Habitat
Wetlands are home to many commercially important animals like
shrimp and crayfish. Young fish find in them a readily
available supply of food as well as protection from predators,
due to their fertile and protective nature. Nearly all the
fish and crustaceans harvested commercially and half of the
recreational catch depend on wetlands for food and habitat
during part of their life cycle (1, 4). A large proportion of
Federally listed threatened or endangered animals (45%) and
plants (26%) depends directly or indirectly on wetlands to
complete their life cycle successfully. They provide migration
routes for wildlife through their natural areas along rivers
and streams which are often "linear corridors", serving as
bridges within and between remaining wildlife habitat (1) .
These quality wetlands are used by millions of migratory
birds and waterfowl which use these ecosystems for food and
shelter during the Spring and Fall migrations north and south,
and for breeding and wintering grounds in summuer and winter.
These connected landscapes can also help to increase or
maintain species diversity and population size of plants and
animals; they also maintain genetic variation within these
populations and provide predator-escape cover for movement
between areas.
1mvrove and maintain Water Quality and Quantity
Wetlands are important for maintaining and improving theI
quality while requlating the quantity of our water. Numerous
studies show that wetlands remove sediments, nutrients and
toxins from the water. Because of their function as removersI
of waste from both natural and human resources, they are
sometimes described as "the kidneys of the landscape". They
are natural water treatment plants; they help to purify water
pollutants that may contaminate and diminish the quality ofI
larger bodies of water (eq. the ocean) . Wetlands also increase
VI-16
water quality by absorbing water in wet seasons, feeding it to
surface and underground water storage areas and gradually
releasing it through wells, springs, seeps or open outlets
during dry periods (1,4).
Wetlands are extensively used for other activities such as
boating, forestry and hunting in many parts of the world, and
to a lesser extent here in the Virgin Islands.
Wetlands have also been appreciated and valued in the field of.
fine arts and literature. For centuries natuiralis`, landscape
painters, photographers and writers have expressed their.
appreciation through their work; and we have all -seen and
enjoyed these pictures and paintings (1,4,5).
Despite their destruction and abuse, wetlands continue to
provide us with valuable services. They form natural
reservoirs, store flood waters, minimize the damage from
severe storms, and provide a home for a wide variety of
important plants and animals. To a large extent, the
characteristics of wetlands and the manner in which they
function are determined by what is happening in the areas
surrounding those wetlands. To understand why this is so we
must understand how hydrology controls wetland sediment supply
and erosion; the availability of oxygen to the organisms that
depend on it; the nutrient supply and biological production
and the channels of access by migratory animals (Fig.1).
ECONOMICAL BENEFITS
Wetlands along the Atlantic and Gulf coasts are especially
critical to the fishing industry in America and support a
multi-billion dollar per year commercial and recreational
fishing industry.
Commercial Fisheries:
A major part of the commercial fisheries catch in the U.S. is
comprised of species that use wetlandsas feeding habitat and
as nursery. Each year, America's commercial fisheries harvest
is valued at more than $10 billion. In the Southeast, an
estimated 96% of the commercial catch and over 50% of the
recreational catch consist of fish and shellfish that depend
on coastal wetland systems. Some of these wetland dependents
are bluefish, sea trout, shrimp, oysters, clams, blue and
Dungenese crabs (Table 1).
Huntinq and Trapping:
Wetlands contribute commercially to support a fur and hide
harvest worth $300-400 million annually. Muskrat and beaver
are the more familiar wetland fur-bearers. Muskrat pelts alone
are worth over $70 million annually.
Recreation:
Wetlands are considered to be "wonderlands". Many recreational
activities such as waterfowl hunting, fishing and crabbing,
take place in and around wetlands. Observation and photography
VI-17
of wetland-dependent birds entice an estimated 50 million
people and they spend nearly $10 billion a year on their
hobby.
Many people simply enjoy the beauty and sound of nature during
their walk along these wetlands (1,6).
This new understanding of the value of wetlands has helped
to increase awareness for the need to re-evaluate the effects
of wetland.-loss.. The White House.press release..also.indicated....
that Federal wetland polity should be based upon the best
scientific information available. It is crucial that we do the
same here in the Virgin Islands. There are a number of people
here in the territory who are interested in some type of
wetland research project. To be complete and effective such
project should include people representing different areas of
the ecosystem, who are equipped to look at the different
aspects of wetland activities:
* as an habitat
* the entire oxidation/reduction sequence
* hydrology
* soil type and
* plant life
VI-18
II WETLAND FOOD CHAIN
,i
Attacked, colonized,
and eaten by Detritus-
.microo°rgan'sms i.T ..ql a mixture
Plants of microorganisms
.* · shredded by small .. and dead plant
II and others
Raw plant food Shrimp, crabs,
Ra plst anst ser sm altcrustaceans,
Marsh plants
feces, containing
plant remains
Ri " - Assimilated food
9Ii' leaves detrital mill
9w . HjE A . ";\ as animaltissue
r .ras support the detrital ood web. Sna animals shred the dead grass. elin r microorganisms to colonize it and brcak il down chemically so that other
can assimilate it and grow their waste products a recolonized by microbes and the cycle s teltaed.
fbe frtagle fringe: coastl etlands of the continental U.S.
VI-19
TABLE I
REVENUE DERIVED FROM WETLANDS IN THE U. S.
Commercial Fisheries 10 Billion
oHunting & Trapping 300-400 Billion
Recreation 10 Billion
TABLE 11
COASTAL WETLAND AREA IN THE VIRGIN ISLANDS
ISLANDS TOTAL WETLAND %
Area
(ha)
ST. CROIX (9) 21,800 598 3
ST. THOMAS (4) 7,300 354 5
ST JOHN (7) 5,200 25. 1
. . .
<p
DEPS3 A I
or
itt. I
0
- I
'I '
:i LITERATURE CITED
1. Watzin M.C., J.G. Gosselink, 1992. The fragile fringe:
coastal wetlands of the continental United States.
Louisiana Sea Grant College Program, Louisiana State
University, Baton Rouge, LA; U.S. Fish and Wildlife
Service, Washington, DC; and National Oceanic and
Atmospheric Administration; Rockville, MD. :
2. Department of the Army, Waterways Experiment Station,
Corps Engineers. 1993. Wetland Delineation
Certification Program.
3. The White House Office on Environmental Policy. August
24, 1993. New Federal wetlands policy offers fair,
flexible approach, ends agency interfighting and
gridlock with strong agreement.
4. American Wetlands Month. May, 1991. Published by the
Office of Wetlands Protection. Washington D.C.
5. National Wetlands Research Center.
6. Frayer W.E., J.M. Hefner. 1991. Florida Wetlands -
Status and Trends, 1970's to 1980's.
7. Scott Derek A. and Montserrat Carbonell. A directory of
|' neotropical wetlands.
f I
I .,
IS.
.I
VII
WINNING STUDENT ENTRIES AND
CLOSING REMARKS
Finding Solutions to Environmental Pollution
Alfredo A. Bough .......................VII-].
Nonpoint Source Pollution
Tishuana Hodge........................VII-3
* Closing Remarks
Joan Har rigan-Farrelly ...................VII-5
Pprntaal ea imeo rnig
FINDING SOLUTIONS TO ENVIRONMENTAL POLLUTION
Alf redo A. Bough
All Saints Cathedral School, St. Thomas, USVI 00802
We, as humans, need to be aware of our environment. Nature and
I. anima ls everywhere are very sensitive to changes in the
* environment including industrial ch eiicals and hbuman wastes.
flY = * Reniembe r; .eare -a- -part -of. -nat.'rei topo..
We need to care about what happens to the trash other people
haphazardly throw away. As a popular commercial on television
advises "GIVE A HOOT, DON'T POLLUTE". This should be taken
seriously and not pushed aside. we require education for
ourselves and our children. This education should be
incorporated into our schools and as well as in our
households. our youth of today depend on us to make this world
a better place for them to live in.
one instance of environmental pollution is cars that we drive
everyday. Carbon monoxide, the harmful culprit of pollution
from motor vehicles, ascends in the atmosphere and in the air
we breathe. Two problems are sparked. one, carbon monoxide can
cause breathing problems and even lung cancer. Two, carbon
monoxide adds to the warming of the earth or more commonly
known as the greenhouse effect.
Raw sewage from pipes that are either broken or run-off
3 directly into our oceans from which we get water and food is
another instance. Instead of allowing this to happen we should
use tax money more wisely and build more effective sewage and
* water desalination plants.
Household and automotive care products such as oil, grease,
heavy metals, and other toxic chemicals can be found in urban
stormwater runoff if not properly disposed of. This can cause
disease and in some cases even death. Contamination of
drinking water with sewage and hazardous minerals can
stimulate many diseases such as typhoid fever, malaria, and
infectious hepatitis. Farmers should use pesticides only when
needed because it can kill fish and contaminate drinking water
3 from runoffs.
Particularly in St. Thomas and coastal states recreational
boating is also a problem. Spilt fuel, untreated sewage and
trash discharged overboard, are not only hazardous to us and
the environment but illegal, too.
We are all a part of the problem so all of us can help to
solve it. everything we do can cause pollution, from
fertilizers to engine oil, and paper plates to styrofoam cups.
You name it and somehow it is a pollutant.
Here are some ways to clean up our island. Please keep litter,
Vii-I
pet wastes, and debris off our street and out of guts. Apply
lawn and garden chemicals sparingly and according to label
directions. Please dispose of oil, anti-freeze, paints, and
other household chemicals properly. Clean up car lubricants
and brake fluid. Don't wash them into the street or gut. I
Dispose of pesticide containers and rinse water properly.
'Maintain your septic system by pumping the tank at least once
every three years. Reduce or prevent soil erosion on your
property.by.....not. .clearing vegetation .or. by planting ..nO.ive L
vegetation as grounid cover-and stbi lzing eroslon-prone.areas
(such as steep, unstable slopes). Minimize manure, fertilizer,
and pesticide applications and time them according to when
plants need these chemicals the most.
To help resolve the environmental pollution problem we can
each do our share to remedy the problem. The aforementioned
paragraph was a list of ways to "HEAL THE WORLD" and "MAKE IT
A BETTER PLACE FOR THE ENTIRE HUMAN RACE". If these guidelines
are followed our island will be a cleaner environment for us
to live in.
VII-2
- -a - -E----
N
STUDENT: Tishuana Hodge
SCHOOL: John H. Woodson Junior High
NOTE: Poster has been reduced. The actual. poster is in color and can be
seen at the Department of Planning and Natural Resources, Nisky Center, St. Thomas, VI
CLOSING REMARKS
Joan Harrigan-Farrelly, CZM Program Manager
Department of Planning and Natural Resources, St. Thomas, VI
00802
Good afternoon ladies and gentlemen.. Over the course of the
past ?two .da.ys.. we.hae triedrtO pnll 7og ether.:r egulator-s,;. .
users and developers to discuss the problems and possible
solutions concerning NPSP..
We heard from the novices who wondered aloud what NPSP was and
we heard from the experts such as Mr. Kimball, Mr. Mc.Comb and
our own Dr. Kojis and Mr. Giruad. We heard from the regulators
both federal and local who told us what the laws , rules and
regulations governing NPSP were and we heard from Dr. Ragstar
who challenged each of us to deal with the problem from a
personal level, from a behavioral level. For as Dr. Ragstar
said only when we modify our day to day living habits, will we
be able to reduce some of the problems and minimize some of
the waste we have been accumulating.
We saw and heard from our youth their perspective on the
problem and possible solutions through their posters and essay
contest, and we heard from the Governor his commitment to
protect and preserve our beautiful islands.
Some of the solutions presented include:
1) looking at our own personal behavior and looking at
ourselves as of contributors to the problem, and
therefore as the ones capable of solving the problem.
2) Revising our laws and statutes in terms of sewage
disposal, earth change practices, septic systems, and
agricultural practices.
3) Utilizing Best Management Practices as far as
construction, agriculture, marinas, and golf courses are
concerned.
4) Reviewing our earth change criteria more carefully and
taking a closer look at erosion and sedimentation control
plans that are presented, and then monitoring the
progress of construction.
5) We heard that the soils of the Virgin Islands are not
conducive to septic systems and a recommendation that all
new housing development must use alternate sewage
disposal systems by the year 1995. This means that our
Public Works Department must have on line adequate, and
state of the art sewage treatment plants, and that
VII-5
private home owners and DPNR must also begin to investigate
individual treatment systems, some of which were discussed
today.
There were numerous other recommendations that came out in the
various sessions, too numerous for me to summarize. However,
we will try to compile all the recommendations and present
them to you with a summary of the proceedings.
So," 'Iere'do wego fromh.ere., what"will we, 6r'hdw 'much will> -
we commit ourselves, Our departments, our agencies and.our
companies to solving this problem? Did we during the course of
the last two days -decide the problem was large enough to
warrant our full combined commitment? From the presentations
and open discussions, I believe that the consensus was that we
will all strive to commit ourselves and our resources to
remedying the problem.
I must add however, that such a problem cannot be solved by
one agency alone, or by the government alone or by one
company. Clearly from the discussions, we are all contributors
to the problem and therefore it will take our collective
efforts to solve the problem. In the same way that it took our
collective efforts to bring about this conference.
Conferences like this are not easy to organize and so I would
like to thank all those who worked diligently in organizing
the conference, contacting the speakers, and getting the word
out. But before I acknowledge all the conference committee
organizers, I would like to single out one person Ms. Janice
Hodge who worked tirelessly to ensure the conference ran
smoothly. Mrs. Hodge you did a wonderful job and I'd like us
to please give her a hand. Other members of the planning
committee included Ms. Julie Wright-UVI Cooperative Extension
Service, Ms. Marcia Taylor, UVI, Eastern Caribbean Center, Mr.
Olasee Davis, UVI Cooperative Extension Service, Mr. Mario
Morales, USDA Soil Conservation Service, Mr. Bruce Green ,
Caribbean Hydro-Tech, Inc., Ms. Algem Petersen DPNR, Division
of Permits, Ms. Lynne MacDonald UVI Eastern Caribbean Center,
and again last but not least, Ms. Janice Hodge Chair of the
committee, DPNR, CZM program.
Allow me also to thank the Governor for opening our
conference, Mr. Richardson for filling in for the
Commissioner, all the presenters, those that came from far and
near, the schools and students that participated in the
poster and essay contest, Limetree Beach Resort, and in
particular Lex and his staff, and you the participants. For
without you there could have been no conference.
Lets leave this conference today with renewed energy and
commitment to working together to solve our problems, and to
making these beautiful islands the paradise they can be.
Vii-6
H Only with government departments joining hands with each other
and the private sector and nongovernment agencies will we be
able to come up with solutions that will benefit all.
I look forward to seeing you at next year's conference.
Once again thank you for your participation.
I-
AUTHOR INDEX
Adams, Roy ............................................................... I-3
Bough, Alfredo ......................................................... VII-1
Boulon, Ralf ............................................................ II-1
Cunningham, Timothy ..................................................... III-6
Davis, :Olas.se .................................. VI-1
Farrelly, Alexander ...................................................... I-1
Giraud, Victor .......................................................... II-6
Harrigan-Farrelly, Joan ................................................ VII-5
Henning, Malcolm ......................................................... 1-9
Hodge, Tishuana ........................................................ VII-3
Hubbard, Dennis ......................................................... V-35
Irizarry, Warner ...................................................... III-23
Kimball, Barry ......................................................... IV-11
Kojis, Barbara .......................................................... V-20
Lindlau, Kim ............................................................ V-18
Linnio, Tom ............................................................. IV-5
MacDonald, Lynne ......................................................... V-1
McComb, William ........................................................ II-25
Morales, Mario ........................................................ III-13
Morton, Dale ........................................................... II-12
Nazario, Benjamin ........................................................ I-5
Padin, Carlos .............................................................. *
Peter, Nathalie ........................................................... V-7
Petersen, Algem ........................................................ VI-15
Petersen, Louis ......................................................... VI-12
Quinn, Norman ........................................................... V-15
Ragster, Laverne ........................................................ 1-15
Reed, Leonard ......................................................... III-11
Richards, Keith ............................................................ *
Schmidt, Jeff ........................................................... VI-9
Selengut, Stanley ....................................................... 1-23
Taylor, Marcia ........................................................ III-1
Wernicke, Werner ....................................................... II-15
White, Douglas ............................................................. *
Wright, Julie ........................................................... IV-1
· Paper not available at time of printing.