[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-

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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.

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                     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.
----------------------------------------------------------------------------------------------------------------

    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
----------------------------------------------------------------------------------------------------------------
                                                                    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)
----------------------------------------------------------------------------------------------------------------
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
----------------------------------------------------------------------------------------------------------------
* 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