[Federal Register Volume 77, Number 162 (Tuesday, August 21, 2012)]
[Notices]
[Pages 50473-50481]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2012-20514]
[[Page 50473]]
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DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
RIN 0648-XA933
Taking of Marine Mammals Incidental to Specified Activities;
Construction of the East Span of the San Francisco-Oakland Bay Bridge
AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and
Atmospheric Administration (NOAA), Commerce.
ACTION: Notice; proposed incidental harassment authorization; request
for comments and information.
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SUMMARY: NMFS has received a request from the California Department of
Transportation (CALTRANS) for an incidental take authorization to take
small numbers of California sea lions, Pacific harbor seals, harbor
porpoises, and gray whales, by harassment, incidental to construction
activities associated with the East Span of the San Francisco-Oakland
Bay Bridge (SF-OBB) in California. Pursuant to the Marine Mammal
Protection Act (MMPA), NMFS is requesting comments on its proposal to
issue an authorization to CALTRANS to incidentally take, by harassment,
small numbers of marine mammals for a period of 1 year. NMFS is also
requesting comments, information, and suggestions concerning CALTRANS'
application and the structure and content of future regulations.
DATES: Comments and information must be received no later than
September 20, 2012.
ADDRESSES: Comments on the application should be addressed to Michael
Payne, Chief, Permits, Conservation and Education Division, Office of
Protected Resources, National Marine Fisheries Service, 1315 East-West
Highway, Silver Spring, MD 20910-3225. The mailbox address for
providing email comments is itp.guan@noaa.gov. NMFS is not responsible
for email comments sent to addresses other than the one provided here.
Comments sent via email, including all attachments, must not exceed a
10-megabyte file size.
Instructions: All comments received are a part of the public record
and will generally be posted to http://www.nmfs.noaa.gov/pr/permits/incidental.htm without change. All Personal Identifying Information
(for example, name, address, etc.) voluntarily submitted by the
commenter may be publicly accessible. Do not submit Confidential
Business Information or otherwise sensitive or protected information.
A copy of the renewal request may be obtained by writing to the
address specified above, telephoning the contact listed below (see FOR
FURTHER INFORMATION CONTACT), or visiting the internet at: http://www.nmfs.noaa.gov/pr/permits/incidental.htm. Documents cited in this
notice may also be viewed, by appointment, during regular business
hours, at the aforementioned address.
FOR FURTHER INFORMATION CONTACT: Shane Guan, Office of Protected
Resources, NMFS, (301) 427-8401.
SUPPLEMENTARY INFORMATION:
Background
Sections 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361 et seq.)
direct the Secretary of Commerce to allow, upon request, the
incidental, but not intentional, taking of small numbers of marine
mammals by U.S. citizens who engage in a specified activity (other than
commercial fishing) within a specified geographical region if certain
findings are made and either regulations are issued or, if the taking
is limited to harassment, a notice of a proposed authorization is
provided to the public for review.
An authorization for incidental takings shall be granted if NMFS
finds that the taking will have a negligible impact on the species or
stock(s), will not have an unmitigable adverse impact on the
availability of the species or stock(s) for subsistence uses (where
relevant), and if the permissible methods of taking and requirements
pertaining to the mitigation, monitoring and reporting of such takings
are set forth. NMFS has defined ``negligible impact'' in 50 CFR 216.103
as ``* * * an impact resulting from the specified activity that cannot
be reasonably expected to, and is not reasonably likely to, adversely
affect the species or stock through effects on annual rates of
recruitment or survival.''
Section 101(a)(5)(D) of the MMPA established an expedited process
by which citizens of the U.S. can apply for a one-year authorization to
incidentally take small numbers of marine mammals by harassment,
provided that there is no potential for serious injury or mortality to
result from the activity. Section 101(a)(5)(D) establishes a 45-day
time limit for NMFS review of an application followed by a 30-day
public notice and comment period on any proposed authorizations for the
incidental harassment of marine mammals. Within 45 days of the close of
the comment period, NMFS must either issue or deny the authorization.
Summary of Request
On October 19, 2011, CALTRANS submitted a request to NOAA
requesting an IHA for the possible harassment of small numbers of
California sea lions (Zalophus californianus), Pacific harbor seals
(Phoca vitulina richardsii), harbor porpoises (Phocoena phocoena), and
gray whales (Eschrichtius robustus) incidental to construction
associated with a replacement bridge for the East Span of the SF-OBB,
in San Francisco Bay (SFB), California. The proposed construction
activities would last for approximately three years, starting 2013.
After receiving NMFS comments on the IHA application regarding proposed
monitoring measures, CALTRANS submitted a revised IHA application on
April 23, 2012. The action discussed in this document is based on
CALTRANS April 23, 2012, IHA application.
An IHA was previously issued to CALTRANS for this activity on
February 7, 2011 and it expired on February 6, 2012 (76 FR 7156,
February 9, 2011). No in-water construction activity was conducted
during the period covered by that IHA. CALTRANS' renewal application
indicates that the next stage of the construction activities will
involve dismantling of the existing bridge, which is expected to start
in fall 2013. However, some preparatory construction activities related
to the dismantling may take place as early as the summer 2012. CALTRANS
also states that the dismantling of the existing east span may take up
to five years to complete, therefore, a five-year LOA under a
rulemaking may seem to be preferable. However, CALTRANS also indicated
that activities involving the existing bridge dismantling are likely to
differ from year to year, and the agency may not be able to predict
annual construction activities in advance. Therefore, it is most likely
that CALTRANS will pursue annual IHAs to take marine mammals incidental
to its construction activities. NMFS is requesting public comment on
whether issuance of five-year regulations would be preferable to
issuance of multiple IHAs. A detailed description of the proposed SF-
OBB East Span project is provided in the CALTRANS' IHA application, and
is summarized below.
Background and Project History
Construction activities for the replacement of the east span of the
SF-OBB commenced in 2002 and are currently ongoing. The new bridge will
consist of four structural sections including (1) the Yerba Buena
Island (YBI) Transition Structure, (2) the Self-
[[Page 50474]]
Anchored Suspension (SAS) Span, (3) the Skyway, and (4) the Oakland
Touchdown. Construction of the Skyway was completed in 2007. The
remaining three structural sections are currently under construction.
The entire Skyway and portions of both the SAS and Oakland Touchdown
span the Bay and have required in-water construction.
The foundations for the piers of the new east span consist of
large-diameter steel pipe piles driven into the Bay floor. Construction
of pier foundations required driving a total of 259 in-Bay large-
diameter permanent steel pipe piles. Of these, 189 piles were 2.5
meters (8.2 feet) in diameter and 70 piles were 1.8 meters (5.9 feet)
in diameter. The larger 2.5-meter (8.2-foot) diameter piles support the
Skyway and SAS sections of the replacement bridge, and were driven to
depths ranging from about -66 meters to about -108 meters (about -217
feet to about -354 feet). The smaller 1.8-meter (5.9-foot) diameter
piles support the Oakland Touchdown structures, and were driven to tip
elevations ranging from about 41 meters to about 65 meters (135 feet to
about 213 feet) below the sediment. All in-Bay pier foundations for the
new east span have been constructed and the driving of in-Bay large-
diameter permanent steel pile piles was complete, as of 2009.
To construct all permanent structures, it was necessary to install
temporary piles to support temporary structures, supports, falsework,
and trestles. These temporary structures were required to facilitate
construction and support the permanent structures until they were self-
supporting. Since the temporary structures were contractor-designed,
their exact nature (size, type, quantity, etc.) was not known until the
contractors submitted their plans to CALTRANS. To date a total of 2,180
temporary piles have been installed. This includes H-piles, cast-in-
drill-hole (CIDH) piles and steel pipe piles ranging from 0.61 meter
(24 inches) to 1.52 meters (60 inches) in diameter. All in-water
temporary pile installation for the construction of the east span was
complete, as of 2009.
On November 10, 2003, NMFS issued an IHA to CALTRANS, authorizing
the take of a small number of marine mammals incidental to the
construction of the SF-OBB Project. The authorization was issued based
on information provided in CALTRANS' IHA request submitted in September
2001. CALTRANS was issued four subsequent IHAs for the SFOBB Project to
date.
The existing east span connecting YBI and the Oakland shoreline was
constructed in 1936. The east span is a double-deck structure 3,696
meters (12,127 feet) in length and approximately 18 meters (58 feet)
wide, carrying five traffic lanes in east-and westbound directions. The
east span is supported by 22 in-water bridge piers (Piers E2 through
E23), as well as land-based bridge piers and bents on both YBI and
Oakland. The existing east span can be divided into three major
sections.
(1) Cantilever Superstructure--The Cantilever section is comprised
of three major elements: two cantilever anchor arm elements that are
154.8 meters (508 feet) long and 156 meters (512 feet) long,
respectively; and a 426.7-meter (1,400-foot) long main span over the
navigation channel consisting of a suspended segment which is supported
on either side by anchor arms. The superstructure of this segment
includes the trusses, road deck and steel support towers.
(2) 504' & 288' Spans Superstructure--This segment of the bridge is
comprised of five 153.6-meter (504-foot) long steel truss spans and
fourteen 87.8-meter (288-foot) long steel truss spans. The vertical
clearance beneath the 504-foot spans is approximately 50 meters (165
feet) above mean high water levels, while the vertical clearance
beneath the 288-foot spans varies greatly as the structure descends
towards the Oakland shoreline. The superstructure of this segment
includes the trusses, road deck and steel and/or concrete support
towers.
(3) Marine Foundations--The in-water or marine foundations vary in
type. Piers E2 through E5 consist of concrete caissons founded on deep
bedrock. Piers E6 through E23 consist of lightly reinforced concrete
foundations that are supported by timber piles.
Remaining Construction Work To Be Completed
1. Completion of New East Span Construction
All in-water pile driving of both permanent and temporary piles for
the construction of the new east span is complete. The only remaining
in-water work with the potential to result in the incidental take of
marine mammals will be the removal of temporary piles. Temporary piles
may be cut off 0.46 meter (1.5 feet) below the mud line or completely
removed. The removal of piles may employ the use of a vibratory pile
driver/extractor.
2. Dismantling of the Existing East Span
East span dismantling activities with the potential to result in
incidental take of marine mammals may include: Dredging and dredged
material disposal, vibratory and impact driving of temporary piles, and
dismantling of marine foundations by mechanical means.
2.1. Dredging and Dredged Material Disposal
Due to shallow water depth near the Oakland shore, dredging may be
required to create a barge access channel to dismantle the existing
bridge. Dredging will also be required to remove piers from the
existing bridge. It is anticipated that 145,785 cubic meters (190,680
cubic yards) of material would be dredged to create the barge access
channel for dismantling the existing bridge.
This material may be disposed of at the San Francisco Deep Ocean
disposal site, at an upland wetland reuse site, or at a landfill reuse
site, as directed by the Dredged Material Management Office (DMMO). For
removal of the existing piers, it is anticipated that 17,374 cubic
meters (22,724 cubic yards) of material will be dredged. This material
may be disposed of at the Alcatraz Island disposal site, or as directed
by the DMMO.
2.2. Vibratory and Impact Driving of Temporary Piles
CALTRANS anticipates that two temporary access trestles and in-
water falsework may be required to dismantle the existing bridge. These
temporary structures, to be designed by the contractor, may be required
to facilitate support of the existing east span until it is completely
removed and provide for construction access. Since the temporary
structures will be contractor designed, their exact nature (size, type,
number of piles, etc.) will not be known until the dismantling begins.
However, CALTRANS has developed estimates as to the approximate size,
location and number of piles needed for these temporary structures. The
anticipated temporary structures are described below and the quantity
and size of piles needed to support these structures are presented in
Table 1.
[[Page 50475]]
Table 1--Estimate of Number and Size of Piles for Temporary Structures
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Maximum Weeks of work
Temporary structure Pile sizes & type Number of Durations of (work will be
piles construction contract intermittent)
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Temporary Supports for the 24'' to 36'' pipe 440 January 2013- 20
Cantilever Superstructure. piles. September 2015.
Temporary Supports for the 504' 24'' to 36'' pipe 450 August 2014-August 20
Superstructure. piles. 2016.
Temporary Supports for the 288' 18'' to 36'' pipe 700 August 2014-August 30
Superstructure. piles. 2016.
Oakland Access Trestle............ 18'' to 36''......... 700 August 2014-July 2017 30
pipe piles...........
YBI Access Trestle................ H-piles.............. 100 January 2013- 4
September 2015.
Other (spud, fender, access, etc.) 18'' to 36'' pipe 150 January 2013-July 6
piles. 2017.
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Two trestles may be needed to facilitate construction access and
allow for the off-haul of materials. One of the trestles would extend
into the Bay from the YBI shoreline (YBI Access Trestle). The other
trestle would extend into the Bay from the Oakland shoreline (Oakland
Access Trestle).
YBI Access Trestle: It is anticipated that a small, approximately
650 square meters (7,000 square ft), H-pile supported trestle would be
constructed on the southeast side of YBI. The YBI Access Trestle would
primarily be used for the off-haul of materials during the dismantling
of the cantilever superstructure. Installation of the YBI Access
Trestle is anticipated as one of the first orders of work for the
dismantling and would likely be constructed during summer or fall 2012.
Oakland Access Trestle: It is anticipated that an approximately
8,920 square meters (96,000 square ft) pipe pile-supported trestle will
be constructed parallel to the southern side of the existing east span.
The trestle would likely have fingers extending under the bridge,
perpendicular to the main trestle to allow for access between the
foundations. It is anticipated that the trestle would extend westward
from the Oakland shoreline, potentially as far as Pier E9 of the
existing east span. The trestle would be used for construction access
during the dismantling of the superstructure and/or marine foundation
removal. The Oakland Access Trestle may be constructed between 2014 and
2017, depending on construction schedules.
Temporary falsework supports would be necessary to ensure the
stability of portions of the structure not yet removed. It is
anticipated that marine pile-supported falsework would be needed to
facilitate the removal of the superstructure.
It is conservatively estimated that a maximum of 2,540 temporary
piles may be installed to support all temporary structures, including
the two access trestles, and falsework needed to support the structural
sections of the existing bridge until completely removed. These piles
are expected to be 0.45 meter (18 inches) to 0.91 meter (36 inches) in
diameter. When no longer needed, all temporary piles will be retrieved
or cut off 0.46 meter (1.5 ft) below the mudline, per US Coast Guard
(USCG) requirements.
All pipe piles will be installed with a vibratory hammer. The
vibratory hammer will be used to drive the majority of the total pile
lengths. The remainder of the pile may be impact-driven with the use of
a marine pile driving energy attenuator (i.e., air bubble curtain
system), or other equally effective sound attenuation method (e.g.,
dewatered cofferdam). A maximum of twenty piles may be impact-driven
per day.
In the event a pipe pile is entirely installed with a vibratory
hammer, it will still be subject to final ``proofing'' with an impact
hammer. ``Proofing'' will be accomplished by using a limited number of
blows with an impact hammer intended to test integrity and seating of
the pile. A maximum of 10% of the piles installed completely with a
vibratory hammer may be proofed with an impact hammer, without the use
of a marine pile driving energy attenuator. Proofing of piles will be
limited to a maximum of two piles per day, for less than 1 minute per
pile, administering a maximum of twenty blows per pile.
All H-piles needed for the construction of the YBI Access Trestle
will be installed with an impact hammer, without the use of a marine
pile driving energy attenuator. Impact driving (with the exception of
pile proofing) will be restricted to the period between June 1 and
November 30 to avoid the peak migration period for salmonids and
spawning adult green sturgeon. Vibratory driving and proofing of piles
may be performed year round.
In addition to the temporary pipe piles and H-piles described
above, sheet piles would be driven with a vibratory hammer to construct
temporary cofferdams. A cofferdam is temporary enclosure, built within
a body of water, usually composed of sheet piles welded together. The
enclosures are generally water tight allowing them to be pumped dry so
that construction may take place in a dry environment. The proposed
cofferdams will be contractor-designed; therefore, the exact number and
exact nature will be dependent on the contractor's means and methods.
It is anticipated that a maximum of 22 cofferdams may be constructed
around in-water marine foundations to facilitate the dismantling of the
foundations. A typical sheet pile is approximately 0.3 meters (1 foot)
long. To construct cofferdams completely surrounding each of the 22
marine foundations a maximum of 7,700 individual sheet piles may be
needed. Due to the physical conditions of the project site (e.g., water
depths) it is very unlikely that all or even a majority of the
cofferdams will be fully dewatered. Some of the cofferdams may be fully
dewatered while others may solely be used to isolate the work area;
preventing water temporarily impacted by construction activities from
mixing with the surrounding waters of the Bay.
2.3. Noise Levels From Pile Driving
To estimate underwater sound pressure levels for the proposed
project, measurements from a number of underwater pile driving projects
conducted under similar conditions were compiled (see Appendix B: Pile
Driving Projects Considered in Development of Underwater Sound level
Estimate in CALTRANS' IHA application). Based on this information,
CALTRANS' hydroacoustic consultant has provided an estimate of
underwater sound levels during vibratory driving, attenuated impact
pile driving, and unattenuated proofing of both 0.61-m (24-in) and
0.91-m (36-in) diameter piles and during impact driving of H-piles to
[[Page 50476]]
determine the distance at which sound levels may exceed specific
thresholds for marine mammal takes (Table 2). The distances from the
pile to the sound level threshold represent the respective exclusion
zone and zones of influence for Level A and Level B harassment (see
below).
Sound level estimates were not prepared for 0.46-m (18-in) diameter
piles. Given that estimated sound levels for 0.61-m (24-in) diameter
piles are lower than those estimated for the 0.91-m (36-in) diameter
piles, it is assumed that sound levels from the vibratory and impact
driving of 0.46-m (18-in) diameter piles will be lower than those for
the 0.91-m (24-in) diameter piles.
Table 2--Estimated Distances Which Sound Levels May Exceed Specific Marine Mammal Take Thresholds
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Distance to Distance to Distance to
Distance to 120 160 dB re 1 180 dB re 1 190 dB re 1
Pile installation method Pile size (m) dB re 1 [micro]Pa [micro]Pa [micro]Pa [micro]Pa
(rms) (m) (rms) (m) (rms) (m) (rms) (m)
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Vibratory Driving............ 24 1,800-2,000 NA <10 * <10 *
36........................... .............. 1,800-2,000 NA <10 * <10 *
Attenuated Impact Driving.... 24 NA 50 <10 <10
36........................... .............. NA 65 <10 <10
Unattenuated Proofing........ 24 NA 385 25 <10
36........................... .............. NA 500 35 <10
Unattenuated Impact Driving.. H-pile NA 330 25 <10
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* Sound pressure levels from vibratory pile driving are not expected to reach 180 dB RMS or 190 dB RMS at any
distance from the pile. However, sound level measurements are generally not taken within less than 10 meters
(33 ft) of piles and the behavior of sound within the near field is not well documented or reliably predicted.
2.4. Dismantling of Marine Foundations by Mechanical Means
Dismantling of concrete foundations would require reducing the
reinforced concrete to pieces small enough to be hauled away, which
could be done by mechanical means such as saw cutting, flame cutting,
mechanical splitting, drilling, pulverizing and/or hydro-cutting.
Dismantling of the marine foundations will be one of the last orders of
work, and will not be undertaken until the superstructures and towers
are removed.
3. Dates, Duration and Geographic Location of the Activities
Construction activities for the replacement of the east span of the
SFOBB commenced in 2002 and are currently ongoing. The majority of the
construction activities to build the new east span are now complete.
The dismantling of the existing span is anticipated to take place
immediately following the opening of the new east span to traffic,
currently expected in the fall of 2013.
Dismantling of the existing east span may take up to five years to
complete. Some preparatory construction activities related to the
dismantling may take place as early as the summer of 2012, with
completion of the dismantling targeted for 2017. The actual work
schedule will be determined by the contractor.
The SF-OBB Project site is located in central San Francisco Bay,
between YBI (which is within the jurisdictional boundaries of the City
and County of San Francisco) and the City of Oakland, in Alameda County
in California, as indicated in Figure 2-1 of CALTRANS LOA application.
Description of Marine Mammals in the Area of the Specified Activity
General information on the marine mammal species found in
California waters can be found in Caretta et al. (2011), which is
available at the following URL: http://www.nmfs.noaa.gov/pr/pdfs/sars/po2010.pdf. Refer to that document for information on these species.
The marine mammals most likely to be found in the SF-OBB area are
the California sea lion, Pacific harbor seal, and harbor porpoise. From
December through May gray whales may also be present in the SF-OBB
area. Information on California sea lion, harbor seal, and gray whale
was provided in the November 14, 2003 (68 FR 64595), Federal Register
notice; information on harbor porpoise was provided in the January 26,
2006 (71 FR 4352), Federal Register notice.
Potential Effects on Marine Mammals and Their Habitat
CALTRANS and NMFS have determined that open-water pile driving and
pile removal, as well as dredging and dismantling of concrete
foundation of existing bridge by saw cutting, flame cutting, mechanical
splitting, drilling, pulverizing and/or hydro-cutting, as outlined in
the project description, has the potential to result in behavioral
harassment of California sea lions, Pacific harbor seals, harbor
porpoises, and gray whales that may be swimming, foraging, or resting
in the project vicinity while pile driving is being conducted. Pile
driving and removal could potentially harass those few pinnipeds that
are in the water close to the project site, whether their heads are
above or below the surface.
Marine mammals exposed to high intensity sound repeatedly or for
prolonged periods can experience hearing threshold shift (TS), which is
the loss of hearing sensitivity at certain frequency ranges (Kastak et
al. 1999; Schlundt et al. 2000; Finneran et al. 2002; 2005). TS can be
permanent (PTS), in which case the loss of hearing sensitivity is
unrecoverable, or temporary (TTS), in which case the animal's hearing
threshold will recover over time (Southall et al. 2007). Since marine
mammals depend on acoustic cues for vital biological functions, such as
orientation, communication, finding prey, and avoiding predators,
marine mammals that suffer from PTS or TTS will have reduced fitness in
survival and reproduction, either permanently or temporarily. Repeated
noise exposure that leads to TTS could cause PTS.
Measured source levels from impact pile driving can be as high as
214 dB re 1 [mu]Pa @ 1 m. Although no marine mammals have been shown to
experience TTS or PTS as a result of being exposed to pile driving
activities, experiments on a bottlenose dolphin (Tursiops truncates)
and beluga whale (Delphinapterus leucas) showed that exposure to a
single watergun impulse at a received level of 207 kPa (or 30 psi)
peak-to-peak (p-p), which is equivalent to 228 dB (p-p) re 1 [mu]Pa,
resulted in a 7 and 6 dB TTS in the beluga whale at 0.4 and 30 kHz,
respectively. Thresholds returned to within 2 dB of the pre-exposure
level within 4 minutes of the exposure (Finneran et al. 2002). No TTS
was observed in the bottlenose dolphin. Although the source level of
pile driving from one hammer strike is expected to be much lower than
the single watergun impulse cited here,
[[Page 50477]]
animals being exposed for a prolonged period to repeated hammer strikes
could receive more noise exposure in terms of SEL than from the single
watergun impulse (estimated at 188 dB re 1 [mu]Pa\2\ = s) in the
aforementioned experiment (Finneran et al. 2002).
Noises from dismantling of marine foundations by mechanical means
include, but is not limited to, saw cutting, mechanical splitting,
drilling and pulverizing. Saw cutting and drilling constitute non-pulse
noise, whereas mechanical splitting and pulverizing constitute impulse
noise. Although the characteristics of these noises are not well
studied, noises from saw cutting and drilling are expected to be
similar to vibratory pile driving, and noises from mechanical splitting
and pulverizing are expected to be similar to impact pile driving, but
at lower intensity, due to the similar mechanisms in sound generating
but at a lower power outputs. CALTRANS states that drilling and saw
cutting is anticipated to produce underwater sound pressure levels
(SPLs) in excess of 120 dB RMS, but is not anticipated to exceed the
180 dB re 1 [mu]Pa (RMS). The mechanical splitting and pulverizing of
concrete with equipment such as a hammer hoe has the potential to
generate high sound pressure levels in excess of 190 dB re 1 [mu]Pa
(RMS) at 1 m.
However, in order for marine mammals to experience TTS or PTS, the
animals have to be close enough to be exposed to high intensity noise
levels for prolonged period of time. Based on the best scientific
information available, these sound levels are far below the threshold
that could cause TTS or the onset of PTS.
In addition, chronic exposure to excessive, though not high-
intensity, noise could cause masking at particular frequencies for
marine mammals that utilize sound for vital biological functions.
Masking can interfere with detection of acoustic signals such as
communication calls, echolocation sounds, and environmental sounds
important to marine mammals. Therefore, under certain circumstances,
marine mammals whose acoustical sensors or environment are being
severely masked could also be impaired from maximizing their
performance fitness in survival and reproduction.
Masking occurs at the frequency band which the animals utilize.
Therefore, since noise generated from in-water pile driving during the
SF-OBB construction activities is mostly concentrated at low frequency
ranges, it may have less effect on high frequency echolocation sounds
by harbor porpoises. However, lower frequency man-made noises are more
likely to affect detection of communication calls and other potentially
important natural sounds such as surf and prey noise. It may also
affect communication signals when they occur near the noise band and
thus reduce the communication space of animals (e.g., Clark et al.
2009) and cause increased stress levels (e.g., Foote et al. 2004; Holt
et al. 2009).
Unlike TS, masking can potentially impact the species at
population, community, or even ecosystem levels, as well as individual
levels. Masking affects both senders and receivers of the signals and
could have long-term chronic effects on marine mammal species and
populations. Recent science suggests that low frequency ambient sound
levels have increased by as much as 20 dB (more than 3 times in terms
of SPL) in the world's ocean from pre-industrial periods, and most of
these increases are from distant shipping (Hildebrand 2009). All
anthropogenic noise sources, such as those from vessels traffic, pile
driving, dredging, and dismantling existing bridge by mechanic means,
contribute to the elevated ambient noise levels, thus intensify
masking.
Nevertheless, the sum of noise from the proposed SF-OBB
construction activities is confined in an area of inland waters (San
Francisco Bay) that is bounded by landmass, therefore, the noise
generated is not expected to contribute to increased ocean ambient
noise. Due to shallow water depth near the Oakland shore, dredging
activities are mainly used to create a barge access channel to
dismantle the existing bridge. Therefore, underwater sound propagation
from dredging is expected to be poor due to the extremely shallowness
of the area to be dredged.
Finally, exposure of marine mammals to certain sounds could lead to
behavioral disturbance (Richardson et al. 1995), such as: Changing
durations of surfacing and dives, number of blows per surfacing, or
moving direction and/or speed; reduced/increased vocal activities,
changing/cessation of certain behavioral activities (such as
socializing or feeding); visible startle response or aggressive
behavior (such as tail/fluke slapping or jaw clapping), avoidance of
areas where noise sources are located, and/or flight responses (e.g.,
pinnipeds flushing into water from haulouts or rookeries).
The biological significance of many of these behavioral
disturbances is difficult to predict, especially if the detected
disturbances appear minor. However, the consequences of behavioral
modification could be expected to be biologically significant if the
change affects growth, survival, and reproduction. Some of these
significant behavioral modifications include:
Drastic change in diving/surfacing patterns (such as those
thought to be causing beaked whale stranding due to exposure to
military mid-frequency tactical sonar);
Habitat abandonment due to loss of desirable acoustic
environment; and
Cease feeding or social interaction.
For example, at the Guerreo Negro Lagoon in Baja California,
Mexico, which is one of the important breeding grounds for Pacific gray
whales, shipping and dredging associated with a salt works may have
induced gray whales to abandon the area through most of the 1960s
(Bryant et al. 1984). After these activities stopped, the lagoon was
reoccupied, first by single whales and later by cow-calf pairs.
The onset of behavioral disturbance from anthropogenic noise
depends on both external factors (characteristics of noise sources and
their paths) and the receiving animals (hearing, motivation,
experience, demography) and is also difficult to predict (Southall et
al. 2007).
The proposed project area is not believed to be a prime habitat for
marine mammals, nor is it considered an area frequented by marine
mammals. Therefore, behavioral disturbances that could result from
anthropogenic noise associated with SF-OBB construction activities are
expected to affect only a small number of marine mammals on an
infrequent basis.
Currently NMFS uses 160 dB re 1 [mu]Pa (RMS) at received level for
impulse noises (such as impact pile driving, mechanic splitting and
pulverizing) as the onset of marine mammal behavioral harassment, and
120 dB re 1 [mu]Pa (RMS) for non-impulse noises (vibratory pile
driving, saw cutting, drilling, and dredging).
As far as airborne noise is concerned, based on airborne noise
levels measured and on-site monitoring conducted during 2004 under a
previous IHA, noise levels from the East Span project did not result in
the harassment of harbor seals hauled out on Yerba Buena Island (YBI).
Also, noise levels from the East Span project are not expected to
result in harassment of the sea lions hauled out at Pier 39 as airborne
and waterborne sound pressure levels (SPLs) would attenuate to levels
below where harassment would be expected by the time they reach that
haul-out site, 5.7 km (3.5 miles) from the project site. Therefore, no
pinniped hauled out would be affected as a result of the proposed pile-
driving. A detailed description of the acoustic
[[Page 50478]]
measurements is provided in the 2004 CALTRANS marine mammal and
acoustic monitoring report for the same activity (CALTRANS' 2005).
Short-term impacts to habitat may include minimal disturbance of
the sediment where individual bridge piers are constructed. Long-term
impacts to marine mammal habitat will be limited to the footprint of
the piles and the obstruction they will create following installation.
However, this impact is not considered significant as the marine
mammals can easily swim around the piles of the new bridge, as they
currently swim around the existing bridge piers.
Estimated Take by Incidental Harassment
For reasons provided in greater detail in NMFS' November 14, 2003
(68 FR 64595) Federal Register notice and in CALTRANS' annual
monitoring reports (CALTRANS 2007; 2010) and marine mammal observation
memoranda under the previous IHAs, the proposed construction activities
would result in harassment of only small numbers of marine mammals and
would not result in more than a negligible impact on marine mammal
stocks and their habitat. This was achieved by implementing a variety
of monitoring and mitigation measures including marine mammal
monitoring before and during pile driving, establishing exclusion
zones, using marine pile driving energy attenuator (i.e., air bubble
curtain system) or other sound attenuation method (e.g., dewatered
cofferdam), and ramping up pile driving.
Marine mammal take estimates are based on marine mammal monitoring
reports and marine mammal observations made during pile driving
activities associated with the SF-OBB construction work authorized
under prior IHAs. For pile driving activities conducted in 2006, 5
harbor seals and no other marine mammals were detected within the
isopleths of 160 dB (rms) re 1 [micro]Pa during impact pile driving
where air bubble curtains were deployed for mitigation measures (radius
of zone of influence (ZOI) at 500 m) (CALTRANS 2007). For pile driving
activities conducted in the 2008 and 2009 seasons, CALTRANS monitored a
much larger ZOI of 120 dB (rms) re 1 [micro]Pa as a result of vibratory
pile driving. A total of 11 harbor seals and 1 California sea lion were
observed entering the 120 dB (rms) re 1 [micro]Pa ZOI (CALTRANS).
However, despite the ZOI being monitored extended to 1,900 m for the
120 dB isopleths, CALTRANS did not specify which pile driving
activities conducted in 2008 and 2009 used an impact hammer and which
ones used a vibratory hammer. Therefore, at least some of these animals
were not exposed to received level above 160 dB (rms) re [micro]Pa, and
thus should not be considered as ``taken'' under the MMPA. No harbor
porpoise or gray whale was observed during CALTRANS' pile driving
activities since 2006 (CALTRANS 2007; 2010).
Based on these results, and accounting for a certain level of
uncertainty regarding the next phase of construction (which would
include dismantling of the existing bridge by mechanical means), NMFS
proposes that at maximum 50 harbor seals, 10 California sea lions, 10
harbor porpoises, and 5 gray whales could be exposed to noise levels
that could cause Level B harassment as a result of the CALTRAN' SF-OBB
construction activities.
Marine Mammal Monitoring Report from Previous IHA
As mentioned above, marine mammal monitoring during CALTRANS' pile
driving activities and weekly marine mammal observation memorandums
(CALTRANS 2007; 2010) indicate that only a small number of harbor seals
(a total of 16 individuals since 2006) and 1 California sea lion (a
total of 1 individual in 2009) were observed within ZOIs that could
result in behavioral harassment. However, the reports state that none
of the animals were observed as been startled by the exposure, which
could be an indication that these animals were habituated to human
activities in San Francisco Bay. In addition, no harbor porpoise or
gray whales were observed during pile driving activities associated to
CALTRANS' SF-OBB construction work.
Proposed Mitigation Measures
CALTRANS worked with NMFS and proposes the following mitigation
measures for its SF-OBB construction activities to reduce adverse
impacts to marine mammals to the lowest extent practicable if in-water
pile driving would be conducted.
Minimization of Impacts From Pile Driving
To minimize potential impacts to marine mammals, CALTRANS states
that it will limit both the size of piles and duration of impact pile
driving, to the extent feasible. Larger piles are expected to generate
higher sound pressure levels than smaller piles. Limiting the size of
piles to 0.91 meter (36 inches) in diameter or smaller will minimize
potential noise impacts.
All pipe piles will be initially installed with a vibratory hammer.
The vibratory hammer will be used to drive the majority of the total
pile lengths. In the event a pipe pile is entirely installed with a
vibratory hammer, it will still be subject to final ``proofing'' with
an impact hammer. A maximum of 10% of the piles installed completely
with a vibratory hammer may be proofed with an impact hammer, without
the use of a marine pile driving energy attenuator. Proofing of piles
will be limited to a maximum of two piles per day, for less than 1
minute per pile, administering a maximum of twenty blows per pile.
While both vibratory and impact pile driving have the potential to
affect marine mammals, impact driving is expected to generate higher
sound pressure levels. Requiring the use of the vibratory hammer will
reduce the duration of impact driving and potential exposure to higher
sound pressure levels.
Use of a marine pile driving energy attenuator (i.e., air bubble
curtain system), or other equally effective sound attenuation method
(e.g., dewatered cofferdam) will be required during impact driving of
all pipe piles, with the exception of pile proofing.
Monitoring and Establishment of Exclusion Zones and Zones of Influence
During prior in-water permanent and some temporary pile driving, a
preliminary 500-meter (1,640-foot) radius exclusion zone was
established prior to the commencement of pile driving. Once pile
driving commenced, acoustical monitoring data was used to determine the
radii at which underwater sound pressure levels equaled or exceeded 180
dB re 1 [micro]Pa (RMS) for cetaceans and 190 dB re 1 [micro]Pa (RMS)
for pinnipeds.
Based on hydroacoustic sound level measured during previous pile
driving events, it is unlikely that sound pressure levels from either
vibratory or impact driving of pipe piles will equal or exceed 180 or
190 dB re 1 [micro]Pa (RMS) beyond 10 meters (33 feet) from the piles.
Therefore, CALTRANS will not establish or monitor an exclusion zone
during vibratory or impact driving of pipe piles.
CALTRANS will perform hydroacoustic monitoring during initial
impact pile driving events for each of the temporary structures
identified in Table 1 to verify estimated underwater sound pressure
levels. Should it be determined through monitoring that sound levels
from the impact driving of pipe piles have the potential to exceed
[[Page 50479]]
180 or 190 dB re 1 [micro]Pa (RMS), corresponding exclusion zones will
be established and monitored in a manner consistent with CALTRANS'
prior IHAs for the SF-OBB Project (see below).
Only the impact driving of H-piles and the proofing of pipe piles
is expected to equal or exceed the 180 dB re 1 [micro]Pa (RMS) to a
distance of 25 to 35 meters (82 to 115 feet) depending on the pile type
and size. However, it is not practical to establish and monitor an
exclusion zone during the driving of H-pile or proofing of pipe piles.
The proofing of a pipe pile would require less than 1 minute of
impact driving. The logistics of scheduling and mobilizing a monitoring
team for activities that will last less than one minute is not
practical. In addition, considering that it is extremely unlikely that
a cetacean would be within 25 to 35 meters (82 to 115 feet) of an H-
pile during impact driving or pipe pile during proofing, CALTRANS does
not intend to establish an exclusion zone or perform monitoring for
cetaceans during these activities. Neither the driving of H-piles or
the proofing of pipe piles is expected to equal or exceed the 190 dB re
1 [micro]Pa (RMS) beyond 10 meters (33 feet) from the pile. Therefore,
a pinniped exclusion zone would not be necessary.
Due to the uncertainty associated with potential sound levels from
mechanical means of dismantling marine foundations, CALTRANS will
establish a preliminary 500-meter radius exclusion zone around each
foundation, prior to splitting or pulverizing concrete via mechanical
means. Once removal of concrete foundations commences, acoustical
monitoring data will be used to determine the radii at which underwater
sound pressure levels equal or exceed 180 dB re 1 [micro]Pa (RMS) for
cetaceans and 190 dB re 1 [micro]Pa (RMS) for pinnipeds. The radii of
the exclusion zones will then be adjusted to correspond with noise
thresholds.
NMFS-approved marine mammal monitors located on construction
barges, trestles, bridge piers, YBI and/or Treasure Island will survey
the exclusion zones to ensure that no marine mammals are seen within
the zone before activities begin. If marine mammals are found within
the exclusion zone, work will be delayed until the monitors are
confident the animal has moved out of the area. If a marine mammal is
seen above water and then dives below, the contractor will be
instructed to wait until enough time has elapsed without a sighting (at
least 15 minutes for pinnipeds and 30 minutes for cetaceans) to assume
the animal has moved beyond the exclusion zone.
If marine mammals enter the safety zone after the activities have
commenced, the operation will continue unabated and marine mammal
observers will monitor and record their numbers and behavior. Should
the activities stop for a period of 30 minutes or more, then the
restart of the activity will be treated in the same manner as described
above.
Should it be determined through acoustic monitoring that sound
levels from the mechanical splitting and pulverizing of concrete
foundations will not have the potential to equal or exceed 180 or 190
dB re 1 [micro]Pa (RMS), monitoring of the exclusion zones will be
discontinued.
Soft Start
It should be recognized that although marine mammals will be
protected from Level A harassment (i.e., injury) through marine mammal
observers monitoring a 190-dB safety zone for pinnipeds and 180-dB
safety zone for cetaceans, mitigation may not be 100 percent effective
at all times in locating marine mammals. Therefore, in order to provide
additional protection to marine mammals near the project area by
allowing marine mammals to vacate the area prior to receiving a
potential injury, CALTRANS would also ``soft start'' the hammer prior
to operating at full capacity. CALTRANS typically implements a ``soft
start'' with several initial hammer strikes at less than full capacity
(i.e., approximately 40-60 percent energy levels) with no less than a 1
minute interval between each strike. Similar levels of noise reduction
are expected underwater. Therefore, the contractor would initiate pile
driving hammers with this procedure in order to allow pinnipeds or
cetaceans in the area to voluntarily move from the area. This should
expose fewer animals to loud sounds both underwater and above water
noise. This would also ensure that, although not expected, any
pinnipeds and cetaceans that are missed during safety zone monitoring
will not be injured.
Compliance With Equipment Noise Standards
In addition, CALTRANS will ensure construction equipment complies
with noise standards of the US Environmental Protection Agency and that
all equipment has noise control devices not less effective than those
provided on the original equipment.
Proposed Monitoring Measures
CALTRANS and NMFS worked together and proposed the following
monitoring measures for the SF-OBB construction activities.
Proposed Monitoring and Reporting Measures
Visual Monitoring
Exclusion zone monitoring will be conducted during the dismantling
of marine foundations by mechanical means having the potential to
generate sound levels in excess of 180 dB re 1 [mu]Pa (RMS). Monitoring
of the pinniped and cetacean exclusion zones will be conducted by a
minimum of three qualified NMFS-approved observers. The observers will
begin monitoring at least 30 minutes prior to startup of the activity
and for at least 30 minutes following the activity. Observers will
likely conduct the monitoring from construction barges, trestles,
bridge piers, YBI and/or Treasure Island depending on the location of
the activity. As discussed above in the proposed mitigation section,
the activity will not begin until the exclusion zone is clear of marine
mammals.
Observations will be made using high-quality binoculars (e.g.,
Zeiss, 10 x 42 power). Monitors will be equipped with radios or cell
phones for maintaining contact with other observers and CALTRANS
engineers, and range finders to determine distance to marine mammals,
boats, buoys, and construction equipment. Data on all observations will
be recorded and will include items such as species, age class and
gender (if possible), numbers, time of observation, location, direction
of travel, and behavior.
Due to the extremely small size of the exclusion zone (zones where
SPL reaches 180 and 190 dB) as indicated in Table 2, there is no need
to conduct monitoring for these zones during pile driving activities.
Should it be determined through hydroacoustic monitoring that sound
levels from pile driving have the potential to substantively exceed 180
or 190 dB re 1 [mu]Pa (rms), corresponding exclusion zones will be
established and monitored.
To document the number of marine mammals exposed to impulse sounds
greater than 160 dB re 1 [mu]Pa (rms), CALTRANS will monitor marine
mammals during at least 20% of attenuated impact driving of pipe piles
and 100% of unattenuated impact driving of H-piles. This monitoring
will be conducted by a minimum of two qualified NMFS-approved protected
species observers (PSOs). The PSOs will begin monitoring at least 30
minutes prior to startup of the activity and for at least 30 minutes
following the activity. PSOs will likely conduct the monitoring from
construction barges, trestles, bridge piers, YBI and/or Treasure Island
[[Page 50480]]
depending on the location of the activity. Data on all observations
will be recorded and will include items such as species, age class, and
sex (if possible), numbers, time of observation, location, direction of
travel, and behavior.
Hydroacoustic Monitoring
The purpose of the underwater sound monitoring during dismantling
of concrete foundations via mechanical means is to establish the
exclusion zones of 180 dB re 1 [mu]Pa (rms) for cetaceans and 190 dB re
1 [mu]Pa (rms) for pinnipeds. Monitoring will occur during the initial
use of concrete dismantling equipment with the potential to generate
sound pressure levels in excess of 180 dB re 1 [mu]Pa (rms). Monitoring
will likely be conducted from construction barges and/or boats.
Measurements will be taken at various distances as needed to determine
the distance to the 180 and 190 dB re 1 [mu]Pa (rms) contours.
The purpose of underwater sound monitoring during impact pile
driving will be to verify sound level estimates and confirm that sound
levels do not equal or exceed 180 dB re 1 [mu]Pa (rms).
Reporting
CALTRANS will notify NMFS prior to the initiation of the pile
driving and dismantling activities for the removal of the existing east
span. NMFS will be informed of the initial sound pressure level
measurements for both pile driving and foundation dismantling
activities, including sound level measurements taken at the 500-meter
(1,640-ft) contour and the final exclusion zone radii established for
marine foundation dismantling activities.
Monitoring reports will be posted on the SFOBB Project's biological
mitigation Web site (www.biomitigation.org) on a weekly basis during
monitoring. Marine mammal monitoring reports will include species and
numbers of marine mammals observed, time and location of observation
and behavior of the animal. In addition, the reports will include an
estimate of the number and species of marine mammals that may have been
harassed as a result of activities. CALTRANS will provide NMFS with a
final report detailing: (1) The monitoring protocol; (2) a summary of
the data recorded during monitoring; and (3) an estimate of the species
and number of marine mammals that may have been harassed due to
activities.
Negligible Impact and Small Numbers Analysis and Determination
Pursuant to NMFS' regulations implementing the MMPA, an applicant
is required to estimate the number of animals that will be ``taken'' by
the specified activities (i.e., takes by harassment only, or takes by
harassment, injury, and/or death). This estimate informs the analysis
that NMFS must perform to determine whether the activity will have a
``negligible impact'' on the species or stock. Level B (behavioral)
harassment occurs at the level of the individual(s) and does not assume
any resulting population-level consequences, though there are known
avenues through which behavioral disturbance of individuals can result
in population-level effects. A negligible impact finding is based on
the lack of likely adverse effects on annual rates of recruitment or
survival (i.e., population-level effects). An estimate of the number of
Level B harassment takes alone is not enough information on which to
base an impact determination.
In addition to considering estimates of the number of marine
mammals that might be ``taken'' through behavioral harassment, NMFS
considers other factors, such as the likely nature of any responses
(their intensity, duration, etc.), the context of any responses
(critical reproductive time or location, migration, etc.), as well as
the number and nature of estimated Level A takes, the number of
estimated mortalities, and effects on habitat.
The CALTRANS' specified activities have been described based on
best estimates of the planned SF-OBB construction project within the
proposed project area. Some of the noises that would be generated as a
result of the proposed bridge construction and dismantling project,
such as impact pile driving, are high intensity. However, the in-water
pile driving for the piles would use small hammers and/or vibratory
pile driving methods, coupled with noise attenuation mechanism such as
air bubble curtains for impact pile driving, therefore the resulting
exclusion zones for potential TS are expected to be extremely small (<
35 m) from the hammer. In addition, the source levels from vibratory
pile driving are expected to be below the TS onset threshold.
Therefore, NMFS does not expect that any animals would receive Level A
(including injury) harassment or Level B harassment in the form of TTS
from being exposed to in-water pile driving associated with SF-OBB
construction project.
Based on marine mammal monitoring reports under previous IHAs, only
16 harbor seals and 1 California sea lion were observed within the 120
dB (in 2008 and 2009) or 160 dB (in 2006) ZOIs during in-water pile
driving since 2006. NMFS estimates that up to 50 harbor seals, 10
California sea lions, 10 harbor porpoises, and 5 gray whales could be
exposed to received levels above 120 dB (rms) during vibratory pile
driving or 160 dB (rms) during impact pile driving for the next season
of construction activities due to the large numbers of piles to be
driven and the extended zones of influence from vibratory pile driving.
These are small numbers, representing 0.15% of the California stock of
harbor seal population (estimated at 34,233; Carretta et al. 2010),
0.00% of the U.S. stock of California sea lion population (estimated at
238,000; Carretta et al. 2010), 0.10% of the San Francisco-Russian
River stock of harbor porpoise population (estimated at 9,181; Carretta
et al. 2010), and 0.05% of the Eastern North Pacific stock of gray
whale population (Allen and Angliss 2010).
Animals exposed to construction noise associated with the SF-OBB
construction work would be limited to Level B behavioral harassment
only, i.e., the exposure of received levels for impulse noise between
160 and 180 dB (rms) re 1 [mu]Pa (from impact pile driving) and for
non-impulse noise between 120 and 180 dB (rms) re 1 [mu]Pa (from
vibratory pile driving). In addition, the potential behavioral
responses from exposed animals are expected to be localized and short
in duration.
These low intensity, localized, and short-term noise exposures
(i.e., 160 dB re 1 [mu]Pa (rms) from impulse sources and 120 dB re 1
[mu]Pa (rms) from non-impulse sources), are expected to cause brief
startle reactions or short-term behavioral modification by the animals.
These brief reactions and behavioral changes are expected to disappear
when the exposures cease. Therefore, these levels of received
underwater construction noise from the proposed SF-OBB construction
project are not expected to affect marine mammal annual rates of
recruitment or survival. The maximum estimated 160 dB isopleths from
impact pile driving is 500 m from the pile, and the estimated 120 dB
maximum isopleths from vibratory pile driving is approximately 2,000 m
from the pile. There is no pinniped haul-out area in the vicinity of
the pile driving sites.
For the reasons discussed in this document, NMFS has preliminarily
determined that the impact of in-water pile driving associated with
construction of the SF-OBB would result, at worst, in the Level B
harassment of small numbers of California sea lions, Pacific harbor
seals, harbor porpoises, and potentially gray whales that inhabit or
visit SFB in general and the vicinity of the SF-OBB
[[Page 50481]]
in particular. While behavioral modifications, including temporarily
vacating the area around the construction site, may be made by these
species to avoid the resultant visual and acoustic disturbance, the
availability of alternate areas within SFB and haul-out sites
(including pupping sites) and feeding areas within the Bay has led NMFS
to preliminarily determine that this action will have a negligible
impact on California sea lion, Pacific harbor seal, harbor porpoise,
and gray whale populations along the California coast.
In addition, no take by Level A harassment (injury) or death is
anticipated and harassment takes should be at the lowest level
practicable due to incorporation of the mitigation measures mentioned
previously in this document.
Impact on Availability of Affected Species for Taking for Subsistence
Uses
There are no relevant subsistence uses of marine mammals implicated
by this action.
National Environmental Policy Act (NEPA)
NMFS' prepared an Environmental Assessment (EA) for the take of
marine mammals incidental to construction of the East Span of the SF-
OBB and made a Finding of No Significant Impact (FONSI) on November 4,
2003. Due to the modification of part of the construction project and
the mitigation measures, NMFS reviewed additional information from
CALTRANS regarding empirical measurements of pile driving noises for
the smaller temporary piles without an air bubble curtain system and
the use of vibratory pile driving. NMFS prepared a Supplemental
Environmental Assessment (SEA) and analyzed the potential impacts to
marine mammals that would result from the modification of the action. A
Finding of No Significant Impact (FONSI) was signed on August 5, 2009.
A copy of the SEA and FONSI is available upon request (see ADDRESSES).
Endangered Species Act (ESA)
NMFS has determined that issuance of the IHA will have no effect on
listed marine mammals, as none are known to occur in the action area.
Proposed Authorization
NMFS proposes to issue an IHA to CALTRANS for the potential
harassment of small numbers of harbor seals, California sea lions,
harbor porpoises, and gray whales incidental to construction of a
replacement bridge for the East Span of the San Francisco-Oakland Bay
Bridge in California, provided the previously mentioned mitigation,
monitoring, and reporting requirements are incorporated. NMFS has
preliminarily determined that the proposed activity would result in the
harassment of only small numbers of harbor seals, California sea lions,
harbor porpoises, and possibly gray whales and will have no more than a
negligible impact on these marine mammal stocks.
Dated: August 15, 2012.
Helen M. Golde,
Acting Director, Office of Protected Resources, National Marine
Fisheries Service.
[FR Doc. 2012-20514 Filed 8-20-12; 8:45 am]
BILLING CODE 3510-22-P