[Federal Register Volume 76, Number 27 (Wednesday, February 9, 2011)]
[Notices]
[Pages 7156-7162]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2011-2892]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

RIN 0648-XZ83


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 of issuance of an incidental harassment authorization.

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SUMMARY: In accordance with provisions of the Marine Mammal Protection 
Act (MMPA) as amended, notification is hereby given that an Incidental 
Harassment Authorization (IHA) has been issued to the California 
Department of Transportation (CALTRANS) to take small numbers of 
California sea lions, Pacific harbor seals, harbor porpoises, and gray 
whales, by harassment, incidental to construction of a replacement 
bridge for the East Span of the San Francisco-Oakland Bay Bridge (SF-
OBB) in California.

DATES: This authorization is effective from February 7, 2011, until 
February 6, 2012.

ADDRESSES: A copy of the application, IHA, and/or a list of references 
used in this document may be obtained by writing to P. Michael Payne, 
Chief, Permits, Conservation and Education Division, Office of 
Protected Resources, National Marine Fisheries Service, 1315 East-West 
Highway, Silver Spring, MD 20910.

FOR FURTHER INFORMATION CONTACT: Shane Guan, NMFS, (301) 713-2289, ext 
137, or Monica DeAngelis, NMFS, (562) 980-3232.

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, the taking is 
limited to harassment, notice of a proposed authorization is provided 
to the public for review.
    Permission shall be granted if NMFS finds that the taking will have 
a negligible impact on the species or stock(s) and will not have an 
unmitigable adverse impact on the availability of the species or 
stock(s) for certain subsistence uses and if the permissible methods of 
taking and requirements pertaining to the mitigation, monitoring, and 
reporting of such taking 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 United States can apply for an authorization 
to incidentally take small numbers of marine mammals by harassment. 
Except with respect to certain activities not pertinent here, the MMPA 
defines ``harassment'' as:

any act of pursuit, torment, or annoyance which (i) has the 
potential to injure a marine mammal or marine mammal stock in the 
wild [Level A harassment]; or (ii) has the potential to disturb a 
marine mammal or marine mammal stock in the wild by causing 
disruption of behavioral patterns, including, but not limited to, 
migration, breathing, nursing, breeding, feeding, or sheltering 
[Level B harassment].

    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 
small numbers of marine mammals. Within 45 days of the close of the 
comment period, NMFS

[[Page 7157]]

must either issue or deny issuance of the authorization.

Summary of Request

    On July 8, 2010, CALTRANS submitted a request to NOAA requesting 
renewal of 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 of a 
replacement bridge for the East Span of the SF-OBB, in San Francisco 
Bay (SFB), California. An IHA was previously issued to CALTRANS for 
this activity on August 14, 2009 and it expired on August 13, 2010 (74 
FR 41684, August 18, 2009). In its renewal request, CALTRANS states 
that it has not scheduled any in-water pile driving and removal for the 
2010-2011 construction year. However, CALTRANS states that due to the 
possibility of unforeseen construction changes, it is important for 
CALTRANS to maintain a current IHA during SF-OBB Project construction 
operations. In addition, CALTRANS stated that should construction 
schedule changes necessitate the installation of in-water piles, these 
would be small diameter temporary piles like the ones used during the 
2009-2010 season, ranging from 0.3 m (18 in) to 1.2 m (48 in); and the 
scale of such events will not exceed the scale of work conducted in the 
previous season. A detailed description of the SF-OBB 2009-2010 
construction work was provided in the August 18, 2009 (74 FR 41684) 
Federal Register notice of issuance of the IHA and is not repeated 
here. The following is a brief summary of CALTRANS 2009-2010 
activities.
    CALTRANS 2009-2010 pile driving activities for 2009-2010 
construction included driving the 42-48 in (1.1-1.2 m) diameter 
temporary piles, as opposed to the much larger 5.9-8.2 ft (1.8-2.5 m) 
diameter permanent piles used in the past. Therefore, the noise from 
pile driving of these temporary piles is far less than that resulting 
from previous pile driving activities. CALTRANS indicates that 
deployment of an air bubble curtain would not be feasible for the 
driving of these smaller temporary piles due to the complexity of the 
driving frames. In addition, during the 2009-2010 construction season, 
certain piles were installed by using both vibratory and impact 
hammers, instead of only impact hammers as in the past.
    Empirical hydroacoustic measurements of impact and vibratory 
hammers during CALTRANS testing of pile driving in San Francisco Bay on 
October 23, December 9, and December 11, 2008, are shown in Table 1. 
Hydroacoustic monitors used data collected on December 9 and December 
11, 2008, to determine the distance of the 120 dB isopleths. At 1,900 m 
from the vibratory pile driving, sound levels are in the low 120 dB 
root-mean-squared (rms) range. At this distance pile driving was 
audible but not measurable due to ambient noise (CALTRANS, 2009).
    If in-water pile driving is to be conducted, the previously 
collected hydroacoustic data showed that the vibration of the bottom 
segment of each pile took approximately 3 minutes; the vibration of the 
top segment of each pile took approximately 8 minutes; and the impact 
driving of the top segment of each pile lasted an average of 15 
minutes. On average, it took about 25 minutes of driving time to 
install each temporary pile (CALTRANS, 2009).

 Table 1--Root-Mean-Square Isopleths Based on Hydroacoustic Monitoring of Pile Driving (48 in. diameter) in San
                          Francisco Bay by Illingworth & Rodkin, Inc. (CALTRANS, 2009)
----------------------------------------------------------------------------------------------------------------
 Sound level (dB-rms re 1 [mu]Pa)      120 \*\          160 \**\         180 \**\              190 \**\
----------------------------------------------------------------------------------------------------------------
Radius for Vibratory Pile Driving  1,900 m........  250 m..........  15 m...........  does not exist.
Radius for Impact Pile Driving...  NA.............  1,000 m........  235 m..........  95 m.
----------------------------------------------------------------------------------------------------------------
* Hydroacoustic measurements for received level at 120 dB (rms) re 1 [mu]Pa from vibratory pile driving were
  collected on December 9 and 11, 2008.
** Hydroacoustic measurements for received levels at 160, 180, and 190 dB (rms) re 1 [mu]Pa from vibratory pile
  driving were collected on October 23, 2008.

    Since the proposed SF-OBB construction project would be installing 
smaller temporary piles with no air bubble curtain, and since the pile 
driving activities would be performed by using both impact and 
vibratory hammers, NMFS conducted a comparison of isopleths from 
CALTRANS' large foundation pile driving activities using an air bubble 
curtain system (Table 2) with the current testing pile driving without 
an air bubble curtain by both impact and vibratory pile driving (Table 
1). The acoustic data used from the foundation pile driving were 
provided by CALTRANS (CALTRANS, 2005). The comparison shows that the 
radius for the zone of influence (ZOI) for Level B behavioral 
harassment, as defined by marine mammals exposed to received impulse 
sound pressure level (SPL) of 160 dB (rms) re 1 [mu]Pa, for the 
previous larger pile driving activities using an air bubble curtain was 
about 2,000 m (see further discussion on potential impacts to marine 
mammals below). This distance is approximately the same as the radius 
for the proposed vibratory pile driving for the smaller temporary piles 
at received SPL of 120 dB (rms) re 1 [mu]Pa, a level that may cause 
Level B behavioral harassment to marine mammals by vibratory pile 
driving. Therefore, NMFS concludes that the potential impacts to marine 
mammals from the proposed SF-OBB construction project involving 
installation of smaller temporary piles using both impact and vibratory 
hammers without deployment of an air bubble curtain system are the same 
as the previous construction activities installing larger foundation 
piles using impact hammers and an air bubble curtain system as a 
mitigation measure. If pile driving or removal are to be conducted, 
they are expected to occur during daylight hours only, as in the 
previous IHAs.

[[Page 7158]]



  Table 2--Summary of Hydroacoustic Measurements of Pile Driving (8.2 ft Diameter) Reported as dB re 1 [mu]Pa--
         Pier E3W Marine Mammal Hydroacoustic Characterization, 10/13/2004 (Adopted From CALTRANS, 2005)
----------------------------------------------------------------------------------------------------------------
                                                  South pile Hammer: Menck 1,700  North pile Hammer: Menck 1,700
            Position                Water depth  ---------------------------------------------------------------
                                                    RMS impulse        Peak         RMS impulse        Peak
----------------------------------------------------------------------------------------------------------------
50m West (made by Caltrans) *...  ..............             177             186  ..............  ..............
100m West *.....................         ~12-14m             175             185             173             182
100m North......................            ~12m             174             183  ..............  ..............
100m South **...................            ~12m  ..............  ..............             174             182
500m West.......................             ~8m             174             182  ..............  ..............
500m South......................            ~10m             167             177             177             188
1000m North.....................             14m  ..............  ..............             169             178
1000m South.....................            ~10m             169             176  ..............  ..............
2000m North.....................             11m  ..............  ..............             162             169
2000m South.....................            ~10m            <140            <150  ..............  ..............
4400m North.....................            >12m  ..............  ..............            <130            <150
4400m South.....................            >12m            <130            <150  ..............  ..............
----------------------------------------------------------------------------------------------------------------
* Continuous measurement. All others are spot measurements of at least 5 minutes in duration.
** Many obstructions including Pier E3E.

Comments and Responses

    A notice of receipt and request for public comment on the 
application and proposed authorization was published on December 13, 
2010 (75 FR 77617). During the 30-day public comment period, the Marine 
Mammal Commission (Commission) provided the only comment.
    Comment: The Commission recommends that NMFS issue the requested 
IHA subject to a condition requiring CALTRANS to make observations 
before, during, and after all soft-starts of pile driving activities to 
gather the data needed to analyze and report on its effectiveness as a 
mitigation measure.
    Response: NMFS agrees that studies are needed to evaluate the 
effectiveness of soft-start or ramp-up procedures as mitigation 
measures prescribed in NMFS incidental take authorizations (ITAs). 
Although soft-start or ramp-up procedures for pile driving have been 
routinely prescribed as a mitigation measure under NMFS ITAs, its 
efficacy has not been assessed. It is believed that by increasing the 
pile driving power incrementally instead of starting with the full 
power, marine mammals that were missed during the 30-minute pre-pile 
driving monitoring would leave the area, thus avoiding temporary 
threshold shift (TTS) or permanent threshold shift (PTS) of hearing 
sensitivity.
    However, given the limited nature of actual pile driving, and 
overall low marine mammal densities and occurrence within parts of the 
San Francisco Bay where the CALTRANS project is located, NMFS does not 
believe that mandating a soft start effectiveness analysis would be 
meaningful or provide enough verifiable data to make any sort of 
reliable, scientific conclusion based on the limited CALTRANS pile 
driving. Nevertheless, NMFS will require CALTRANS to note any 
observations during the entire pile driving sequence, including the 
``soft-start'' period, for later analysis. This analysis could provide 
some insights regarding the effectiveness of prescribing soft-start or 
ramp up as a mitigation measure for pile driving.

Potential Effects on Marine Mammals and Their Habitat

    CALTRANS and NMFS have determined that open-water pile driving, 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 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, 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).
    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.

[[Page 7159]]

    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 vessel traffic, pile 
driving, and dredging activities, 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.
    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 at received level for 
impulse noises (such as impact pile driving) as the onset of marine 
mammal behavioral harassment, and 120 dB re 1 [mu]Pa for continued 
noises (vibratory pile driving 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 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 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 safety zones, 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 microPa during impact pile driving where 
air bubble curtains were deployed for mitigation measures (radius of 
ZOI at 500 m) (CALTRANS 2007). For pile driving activities conducted in 
the 2008 and 2009 seasons, CALTRANS monitored a much

[[Page 7160]]

larger ZOI of 120 dB (rms) re 1 microPa 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 microPa ZOI (CALTRANS). 
However, despite the monitored ZOI being extended to 1,900 m for the 
120 dB isopleths, CALTRANS did not specify which pile driving 
activities conducted in 2008 and 2009 used impact hammer and which ones 
used vibratory hammer. Therefore, at least some of these animals were 
not exposed to received levels above 160 dB (rms) re 1 microPa, and 
thus should not be considered as ``taken'' under the MMPA. No harbor 
porpoise or gray whale were observed during CALTRANS' pile driving 
activities since 2006 (CALTRANS 2007; 2010).
    Based on these results, in addition to CALTRANS' expectation that 
very limited pile driving activities would be conducted in the next 
season, NMFS concludes that at a maximum of 10 harbor seals, 2 
California sea lions, 5 harbor porpoises, and 1 gray whale could be 
exposed to noise levels above 120 dB by vibratory pile driving.

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 to have 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.

Mitigation Measures

    For the issuance of the IHA for the planned 2011-2012 SF-OBB 
potential construction activities to reduce adverse impacts to marine 
mammals to the lowest extent practicable, NMFS requires the following 
mitigation measures to be implemented.

Establishment of Safety/Buffer Zones

    CALTRANS conducted underwater acoustic measures during temporary 
pile driving using impact hammers conducted under the previous IHA 
(CALTRANS 2010). The measurements showed that the distance to the 190 
dB (rms) re 1 [mu]Pa isopleths ranged from 50 m (164 ft) to 150 m (492 
ft), and the distance to the 180 dB (rms) re 1 [mu]Pa isopleths ranged 
from 375 m (1,230 ft) to 500 m (1,640 ft) at different locations. NMFS 
required CALTRANS to use the most conservative measurements for the 
establishment of safety zones at 500 m (1,640 ft) for pinnipeds and at 
150 m (492 ft) for cetaceans. These safety zones shall be monitored at 
all times when impact pile driving is underway.
    No safety zone would be established for vibratory pile driving and 
removal since the measured source levels will not exceed the 180 and 
190 dB re 1 [mu]Pa.
    Observers on boats would survey the safety zone to ensure that no 
marine mammals are seen within the zones before impact pile driving of 
a pile segment begins. If marine mammals are found within the safety 
zone, impact pile driving of the segment would be delayed until they 
move out of the area. If a marine mammal is seen above water and then 
dives below, the contractor would wait 15 minutes for pinnipeds and 
harbor porpoise and 30 minutes for gray whale. If no marine mammals are 
seen by the observer in that time it would be assumed that the animal 
has moved beyond the safety zone. This 15-minute criterion is based on 
scientific evidence that harbor seals in San Francisco Bay dive for a 
mean time of 0.50 minutes to 3.33 minutes (Harvey and Torok, 1994), and 
the mean diving duration for harbor porpoises ranges from 44 to 103 
seconds (Westgate et al., 1995).
    Once the pile driving of a segment begins it cannot be stopped 
until that segment has reached its predetermined depth due to the 
nature of the sediments underlying the Bay. If pile driving stops and 
then resumes, it would potentially have to occur for a longer time and 
at increased energy levels. In sum, this would simply amplify impacts 
to marine mammals, as they would endure potentially higher SPLs for 
longer periods of time. Pile segment lengths and wall thickness have 
been specially designed so that when work is stopped between segments 
(but not during a single segment), the pile tip is never resting in 
highly resistant sediment layers. Therefore, because of this 
operational situation, if seals, sea lions, or harbor porpoises enter 
the safety zone after pile driving of a segment has begun, pile driving 
will continue and marine mammal observers will monitor and record 
marine mammal numbers and behavior. However, if pile driving of a 
segment ceases for 30 minutes or more and a marine mammal is sighted 
within the designated safety zone prior to commencement of pile 
driving, the observer(s) must notify the Resident Engineer (or other 
authorized individual) immediately and follow the mitigation 
requirements as outlined previously in this document.

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. 
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

    To mitigate noise levels and, therefore, impacts to California sea 
lions, Pacific harbor seals, harbor porpoises, and gray whales, all 
construction equipment shall comply with applicable equipment noise 
standards of the U.S. Environmental Protection Agency, and all 
construction equipment shall have noise control devices no less 
effective than those provided on the original equipment.

Monitoring Measures

    The following monitoring measures are required for the proposed SF-
OBB construction activities.
    Safety zone monitoring would be conducted during pile driving and 
removal of all in-water piles. Monitoring of the pinniped and cetacean 
safety zones shall be conducted by a minimum of three qualified NMFS-
approved observers for each safety zone. One three-observer team would 
be required

[[Page 7161]]

for the safety zones around each pile driving site, so that multiple 
teams would be required if pile driving is occurring at multiple 
locations at the same time. The observers would begin monitoring at 
least 30 minutes prior to startup of the pile driving, including the 
period of ``soft start.'' Most likely observers would conduct the 
monitoring from small boats, as observations from a higher vantage 
point (such as the SF-OBB) are not practical. Pile driving should not 
begin until the safety zones are clear of marine mammals. However, as 
described in the Mitigation section, once pile driving of a segment 
begins, operations would continue uninterrupted until the segment has 
reached its predetermined depth. However, if pile driving of a segment 
ceases for 30 minutes or more and a marine mammal is sighted within the 
designated safety zone prior to commencement of pile driving, the 
observer(s) must notify the Resident Engineer (or other authorized 
individual) immediately and follow the mitigation requirements as 
outlined previously (see Mitigation). Monitoring should continue 
through the pile driving period and would end approximately 30 minutes 
after pile driving has been completed. Biological observations would be 
made using binoculars during daylight hours.
    In addition to monitoring from boats, during in-water pile driving, 
monitoring at one control site (i.e., harbor seal haul-out sites and 
the waters surrounding such sites not impacted by the East Span 
Project's pile driving activities, e.g., Mowry Slough) would be 
designated and monitored for comparison. Monitoring would be conducted 
twice a week at the control site whenever in-water pile driving is 
being conducted.
    Data on all observations would be recorded and should include the 
following information:
    (1) Location of sighting;
    (2) Species;
    (3) Number of individuals;
    (4) Number of calves present;
    (5) Duration of sighting;
    (6) Behavior of marine animals sighted;
    (7) Direction of travel;
    (8) Environmental information associated with sighting event 
including Beaufort sea state, wave height, tide state, water currents, 
wind direction, visibility, glare, percentage of glare, percentage of 
cloud cover; and
    (9) When in relation to pile driving or removal activities did the 
sighting occur (before, ``soft-start,'' during, or after the pile 
driving or removal).
    The reactions of marine mammals would be recorded based on the 
following classifications that are consistent with the Richmond Bridge 
Harbor Seal survey methodology (for information on the Richmond Bridge 
authorization, see 68 FR 66076, November 25, 2003): (1) No response, 
(2) head alert (looks toward the source of disturbance), (3) approach 
water (but not leave), and (4) flush (leaves haul-out site). The number 
of marine mammals under each disturbance reaction should be recorded, 
as well as the time when seals re-haul after a flush.

Reporting Measures

    Under previous IHAs, CALTRANS submitted weekly marine mammal 
monitoring reports for the time when in-water pile driving was 
commenced. In June 2010, CALTRANS submitted the Marine Mammal 
Monitoring for the Self-anchored Suspension Span Temporary Tower, which 
also includes hydroacoustic measurements during both impact and 
vibratory pile driving. The report is available by contacting NMFS (see 
ADDRESSES).
    Under the IHA, coordination with NMFS would occur on a weekly basis 
if pile driving or removal is conducted. During periods with in-water 
pile driving or removal activities, weekly monitoring reports will be 
made available to NMFS and the public at http://biomitigation.org. 
These weekly reports would include a summary of the previous week's 
monitoring activities and an estimate of the number of seals and sea 
lions that may have been disturbed as a result of pile driving 
activities.
    In addition, CALTRANS would provide NMFS with a draft final report 
within 90 days after completion of the westbound Skyway contract and 90 
days after completion of the Suspension Span foundations contract. This 
report should detail the monitoring protocol, summarize the data 
recorded during monitoring, and estimate the number of marine mammals 
that may have been harassed due to pile driving. If no comments are 
received from NMFS within 30 days, the draft final report would be 
considered the final report. If comments are received, a final report 
must be submitted within 30 days after receipt of comments.

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 project, such as impact pile 
driving, are high intensity. However, the in-water pile driving for the 
test piles, if conducted, would use small hammers and/or vibratory pile 
driving methods, therefore the resulting safety zones for potential TS 
are expected to be small and can be easily monitored to ensure no 
marine mammals are within the zones when pile driving starts. 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 the 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 proposes that up to 10 harbor seals, 2 
California sea lions, 5 harbor porpoises, and 1 gray whale could be 
exposed to received levels above 120 dB (rms) during vibratory pile 
driving or

[[Page 7162]]

160 dB (rms) during impact pile driving for the next season of 
construction activities if pile driving frequency would be kept at 
2008-2009 level. These are small numbers, representing 0.03% 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), 0.05% of the 
San Francisco-Russian River stock of harbor porpoise population 
(estimated at 9,181; Carretta et al. 2010), and 0.01% of the Eastern 
North Pacific stock of gray whale population (estimated at 18,813; 
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 average measured 160 dB isopleths from 
impact pile driving is 1,000 m from the pile, and the estimated 120 dB 
isopleths from vibratory pile driving is approximately 1,900 m from the 
pile.
    For the reasons discussed in this document, NMFS has 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 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 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. The activity will not have an unmitigable 
adverse impact on subsistence uses of marine mammals described in MMPA 
section 101(a)(5)(D)(i)(II).

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)

    On October 30, 2001, NMFS completed consultation under section 7 of 
the ESA with the Federal Highway Administration (FHWA) on the CALTRANS' 
construction of a replacement bridge for the East Span of the SF-OBB in 
California. Anadromous salmonids are the only listed species which may 
be affected by the project. The finding contained in the Biological 
Opinion was that the proposed action at the East Span of the SF-OBB is 
not likely to jeopardize the continued existence of listed anadromous 
salmonids, or result in the destruction or adverse modification of 
designated critical habitat for these species. Listed marine mammals 
are not expected to be in the area of the action and thus would not be 
affected.
    NMFS' issuance of an IHA to CALTRANS constitutes an agency action 
that authorizes an activity that may affect ESA-listed species and, 
therefore, is subject to section 7 of the ESA. There is no ESA-listed 
marine mammal species in the proposed action area, therefore, NMFS has 
determined that issuance of an IHA for this activity will have no 
effect on any listed marine mammal species.

Authorization

    NMFS has issued 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 Franciso-Oakland Bay Bridge in California, 
provided the previously mentioned mitigation, monitoring, and reporting 
requirements are incorporated.

    Dated: February 2, 2011.
James H. Lecky,
Director, Office of Protected Resources, National Marine Fisheries 
Service.
[FR Doc. 2011-2892 Filed 2-4-11; 4:15 pm]
BILLING CODE 3510-22-P