[Federal Register Volume 64, Number 121 (Thursday, June 24, 1999)]
[Pages 33848-33851]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-16145]



Department of the Army, Corps of Engineers

Intent To Prepare an Environmental Impact Statement/Report/
Feasibility Study for the White Slough Flood Control Study, City of 
Vallejo, Solano County, CA

AGENCY: U.S. Army Corps of Engineers, DoD.

ACTION: Notice of intent.


SUMMARY: The purpose of the feasibility study is to identify and 
evaluate alternatives which will lead to flood protection for areas 
adjacent to White Slough, south of Highway 37 in Vallejo. To fulfill 
the requirements of Section 102(2)(c) of the National Environmental 
Policy Act, the Corps of Engineers has determined that the proposed 
action may have significant effect on the quality of the human 
environment and

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therefore requires the preparation of an Environmental Impact 
Statement. This document will also serve as the Environmental Impact 
Report (EIR) under the California Environmental Quality Act (CEQA). 
Lead Agency under CEQA is the Vallejo Sanitation and Flood Control 
District. This environmental assessment is required by the National 
Environmental Policy Act of 1969, as amended (PL 91-190). Section 
102(2)(A) requires Federal agencies to: ``Utilize a systematic 
interdisciplinary approach which will insure the integrated use of the 
natural and social sciences and the environmental design arts in 
planning and decision making which may have an impact on man's 

FOR FURTHER INFORMATION CONTACT: Written comments and questions 
regarding the scoping process or preparation of the EIS/EIR/FS may be 
directed to Craig Vassel, U.S. Army Corps of Engineers, San Francisco 
District, 333 Market Street, 717P, Seventh Floor, San Francisco, CA 
94105-2197, (415) 977-8546, Fax: 415-977-8695, Email: 


1. Authority

    Pursuant to Section 102(2)(c) of the National Environmental Policy 
Act (NEPA) of 1969 as implemented by the Council on Environmental 
Quality regulations (40 CFR Parts 1500-1508), the California 
Environmental Quality Act (CEQA), the Department of the Army and 
Vallejo Sanitation and Flood Control District hereby give notice of 
intent to prepare a joint Environmental Impact Statement/Environmental 
Impact Report/Feasibility Study (EIS/EIR/FS) for the White Slough Flood 
Control Project, Solano County, California.

2. Comments/ Scoping Meetings

    Interested parties are requested to express their views concerning 
the proposed activity. The public is encouraged to provide written 
comments in addition to or in lieu of, oral comments at the scoping 
meeting. To be most helpful, scoping comments should clearly describe 
specific environmental topics or issues, which the commentator believes 
the document, should address. Oral and written comments receive equal 
consideration. Two workshop-scoping sessions will be held on Wednesday 
July 7, 1999. The first 2:30-4:30 is intended primarily for local, 
state, and federal agencies and organizations. The second 7:00-9:00 is 
intended for all interested parties. Both meetings will be at the 
offices of the Vallejo Sanitation and Flood Control District Offices, 
450 Ryder Avenue, Vallejo, CA.

3. Availability of EIS/EIR/FS

    The Draft EIS/EIR/FS should be available for public review in Fall 

4. Agencies Supporting Project.

    The U.S. Army Corps of Engineers and Vallejo Sanitation and Flood 
Control District will be the lead agencies in preparing the combined 
EIS/EIR/FS. The EIS/EIR/FS will provide an analysis supporting both the 
requirements of NEPA and CEQA in addressing impacts to the environment 
which may result from implementation of flood control measures.

5. Purpose and Need for Project:

    This project is intended to reduce the risk of flooding from all 
sources in the vicinity of White Slough, south of Highway 37 in 

6. Study Area Description

    White Slough is bisected by Highway 37. The southern portion, south 
of Highway 37 which is part of the Slough or subject and flooding is 
the study area for this project.

7. Levee Construction History

    a. Located between the Napa River and the City of Vallejo, White 
Slough receives both tidal flow from the Napa River and fluvial flow 
from Chabot and Austin Creeks. Around 1900, local interests constructed 
a levee along the east bank of the Napa River, which allowed for the 
reclamation of approximately 816 acres of wetlands adjacent to White 
Slough; 604 acres west of Highway 37 and 212 acres southeast of Highway 
    b. After floods breached these levees in 1964 and 1969, the Corps 
of Engineers subsequently repaired them. The 1969 repairs were 
performed under the authority of Public Law 81-875, which requires that 
local interests maintain the repaired levees. Floods again breached the 
levees in the winters of 1976, 1977, and 1978. This time, since 
inspections indicated that little or no levee maintenance had been done 
by local interests since they were last repaired in 1969, the Corps of 
Engineers had no authority to repair the levees. The land owners of 
property protected by the levees refused to make repairs without a 
guarantee that they could develop their land. During this period, the 
Bay Conservation and Development Commission (BCDC) claimed jurisdiction 
over the White Slough area. Little activity has occurred within the 
White Slough area in the intervening years.

8. Austin Creek

    Austin Creek flows in an unlined channel along the southern 
perimeter of White Slough. Flow in this channel is carried by three 
road culverts. Because Austin Creek is separated from White Slough by a 
low levee (six feet NGVD), it can only be drained by the Austin Creek 
Pump Station.

9. 1983 Tidal Flooding

    In 1983, a tide in excess of the 100-year event, combined with 
storm runoff, caused extensive flooding in the vicinity of White 
Slough. The Austin Creek Channel levee was overtopped, and flooding 
occurred on Sacramento Street, Sonoma Boulevard, and in the Larwin 
Plaza and K-Mart areas. After this event, the Austin Creek levee was 
raised by about three feet on the outboard side to protect the 
Sacramento Street area against tidal flooding. Today, the only tidal 
flooding protection in the White Slough area is provided by an 
emergency levee along the northern side of Highway 37, constructed by 
the City of Vallejo.

10. Fluvial Flooding Problem

    Austin Creek's overtopping is the primary cause of fluvial 
flooding. The Austin Creek Pump Station provides adequate outlet 
capacity for three to five year fluvial flood events, but the channel 
and road crossing culverts do not convey flow to the pumps fast enough. 
During past flood events, the pump station pumped the immediate 
upstream channel reach nearly dry, while water was still ponding to 
significant depths behind the Redwood Street and Valle Vista Street 
culverts. Backwater conditions and obstruction by debris greatly reduce 
the capacities of the bridge culverts at Redwood Street and Valle Vista 
Avenue. The 100-year design flow of 1583 cfs significantly exceeds 
channel and culvert capacities regardless of backwater conditions.

11. Highway 37 Project

    Caltrans' will use fill to raise and widen the highway and install 
additional culverts with tide gates under Highway 37. This will provide 
limited tidal exchange and tidal flood protection to the highway and 
the study area south of the highway subject to tidal flooding.

12. Project Alternatives

    a. No action. This alternative assumes that no flood control 
project, structural or non-structural, other than the Highway 37 
project, will be

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implemented in the project area by the federal government or any other 
entity. Flooding would continue at the same frequency and intensity as 
it has in the past. Tidal flooding would be controlled by the Caltrans 
Highway 37 project. Inadequately protected areas around White Slough 
would continue to risk flood damage.
    b. Flood Control Alternatives. Preliminary flood damage reduction 
alternatives studied for the White Slough and Austin Creek areas fall 
into two categories: Tidal and fluvial.

13. Tidal Flood Protection From Highway 37

     Tidal flood protection to the highway and to those portions of the 
study area south of the highway subject to tidal flooding will be 
provided by Caltrans' Highway 37 improvement project. The project 
includes using fill to raise and widen Highway 37. Four additional 48-
inch diameter culverts with tide gates under Highway 37 will limit 
tidal exchange to provide tidal flood protection. Levee protection 
would be required in areas where the existing tidal barrier falls below 
the 100-year tidal flood event.

14. Fluvial Alternatives.

    Several alternatives to control fluvial flooding will be 
    a. Retention ponds. Two retention ponds, each 10 feet deep, would 
be constructed on vacant land adjacent to Austin Creek just west of 
Sonoma Boulevard, creating a total of 60 acre-feet of storage upstream 
of Valle Vista Avenue. Storage of floodwater does not occur naturally 
at this site; therefore, any storage would have to be developed through 
excavation of native material and artificial fill on the property. Flow 
diverted into the basins would then drain by gravity back into the 
channel at a slower rate.
    b. Bridge improvements. To decrease backwater conditions caused by 
obstructions; thereby increasing the capacity of Austin Creek, bridge 
improvements are being considered as well as removal of the abandoned 
culvert structure between Redwood Street and Highway 37. New pipes 
could be added to existing culvert bridge structures at Redwood Street 
and Valle Vista Avenue, or the existing culvert structures replaced 
with larger box culverts or clear span bridges.
    c. Pump station improvements. The pump station at Austin Creek is 
limited in capacity. Any alternative which increases the capacity of 
Austin Creek could require an upgrading of the Austin Creek Pump 
Station, or a diversion of Austin Creek storm flow to a storage 
facility, such as White Slough, for retention.
    d. Austin Creek flow diversion. If excess flows in Austin Creek 
above the Redwood Street and Valle Vista Avenue bridges are diverted, 
this could eliminate or reduce the need to upgrade the bridges. To 
divert these flows, a 2400-foot parallel pipe system would carry flows 
from the basin above Austin Creek directly into White Slough a clear 
passage of flow from Austin Creek into White Slough by removal of the 
levee system along the eastern bank of Austin Creek between Redwood 
Street and Highway 37, or directly into Austin Creek below Valle Vista 
Avenue or Redwood Street. This diversion structure could be combined 
with creation of a confluence between Austin Creek and White Slough. If 
White Slough received excess flows from Austin Creek during high flow 
periods, the existing Austin Creek Pump Station could then drain White 
Slough. The best location for such a confluence appears to be along the 
levee that separates Austin Creek from White Slough. Controllable gates 
could be installed within the barrier separating Austin Creek from 
White Slough.
    e. Austin Creek Creekside protection. Levees or floodwalls by 
themselves or in combination with other improvement options may also be 
used to increase the capacity of the Austin Creek channel. This 
alternative does not address the causes of flooding, but merely 
contains the flow within Austin Creek.
    f. Removal of levees/restore confluence of Austin Creek and White 
Slough. 1000 lineal feet of levee along the east bank and 1000 lineal 
feet of floodwalls on the west bank of Austin Creek between Redwood 
Street and Valle Vista and 1500 lineal feet of floodwalls on both banks 
of Austin Creek extending from Valle Vista Avenue to the upstream?would 
create a clear passage of flow in Austin Creek from Redwood Street to 
Highway 37.
    g. Perimeter flood protection. 2000 lineal feet of floodwall and 
2500 feet of levee along the perimeter of White Slough south of Highway 
37, 1000 lineal feet of levee along the east bank and 1000 lineal feet 
of floodwalls on the west bank of Austin Creek between Redwood Street, 
and Valle Vista and 1000 lineal feet of floodwalls on both banks of 
Austin Creek extending from Valle Vista Avenue to the downstream limit 
of the retention ponds would be constructed.

15. Feasibility Study

    The five-phase Feasibility Study will identify and evaluate 
measures to restore lost tidal prism and reduce the rate of 
sedimentation as follows:
    a. Phase One will investigate existing physical and environmental 
conditions restoration needs and constraints of the area. The future 
without-project conditions in the study area will be projected. Input 
on the ecosystem will be sought from resource agencies and the public. 
Public scoping workshops will be held both in Vallejo.
    b. During Phase Two, hydraulic modeling of the preliminary 
alternatives will be completed and economics and environmental impacts 
    c. In Phase Three, preliminary alternatives will be evaluated and 
benefits of the alternatives will be quantified. A draft Fish and 
Wildlife Coordination Act Report possibly including a Habitat 
Evaluation Procedure (HEP) will be prepared to help provide the basis 
for identifying the most cost-effective alternative acceptable to the 
agencies and community.
    d. Phase Four involves preparing the draft Feasibility Report and 
Environmental Impact Statement/Report (EIS/R). The EIS/R will analyze 
all reasonable alternatives and evaluate compliance with federal and 
state environmental requirements. A formal public review and comment 
period will be started.
    e. The last phase of the study includes preparing the final 
Feasibility Report recommending a preferred alternative and completing 
the final EIS/R which will respond to all comments on the draft EIS/R.

16. Other Environmental Review and Consultation Requirements

    The DEIS/R will be used as the primary information document to 
secure concurrence in a Federal Coastal Zone Consistency Determination 
to comply with Clean Water Act Section 404 (b) (1) guidelines, the Fish 
and Wildlife Coordination Act, and the Endangered Species Act. The 
DEIS/R will be used by the local sponsor to meet its responsibilities 
under the California Environmental Quality Act, and used by the San 
Francisco Regional Water Quality Control Board to meet its 
responsibilities under the Porter-Cologne Act. The DEIS/R will be used 
for ``trustee agency'' reviews by the State of California.

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17. DEIS Availability

    The DEIS will be available to the public in Fall 1999.

Peter T. Grass,
LTC, EN, Commanding.
[FR Doc. 99-16145 Filed 6-23-99; 8:45 am]