[Federal Register Volume 74, Number 232 (Friday, December 4, 2009)]
[Notices]
[Pages 63724-63731]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E9-28991]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

RIN 0648-XS23


Small Takes of Marine Mammals Incidental to Specified Activities; 
Dumbarton Bridge Seismic Retrofit Project, California

AGENCY:  National Marine Fisheries Service (NMFS), National Oceanic and 
Atmospheric Administration (NOAA), Commerce.

ACTION:  Notice; proposed incidental harassment authorization; request 
for comments.

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SUMMARY: SNMFS has received an application from the California 
Department of Transportation (Caltrans) for an Incidental Harassment 
Authorization (IHA) to take marine mammals, by Level B harassment, 
incidental to retrofitting the Dumbarton Bridge, located in southern 
San Francisco Bay (Bay), California. Pursuant to the Marine Mammal 
Protection Act (MMPA), NMFS is requesting comments on its proposal to 
issue an IHA to Caltrans to incidentally harass harbor seals (Phoca 
vitulina richardii), California sea lions (Zalophus californianus), and 
gray whales (Eschrichtius robustus) during the specified activity.

DATES:  Comments and information must be received no later than January 
4, 2010.

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 [email protected]. NMFS is not 
responsible for e-mail comments sent to addresses other than the one 
provided here. Comments sent via e-mail, including all attachments, 
must not exceed a 10-megabyte file size. NMFS is not responsible for 
comments sent to addresses other than the ones listed here.
    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.

[[Page 63725]]

    A copy of the application containing a list of the references used 
in this document 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 be viewed, by appointment, during regular business hours, at 
the aforementioned address.

FOR FURTHER INFORMATION CONTACT:  Jaclyn Daly, Office of Protected 
Resources, NMFS, (301) 713-2289.

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. 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].''
    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 United States can apply for an authorization 
to incidentally take small numbers of marine mammals by 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 marine 
mammals. Within 45 days of the close of the comment period, NMFS must 
either issue or deny the authorization.

Summary of Request

    On April 17, 2009, NMFS received a request from Caltrans to harass 
marine mammals incidental to the Dumbarton Bridge Seismic Retrofit 
Project. The application was determined complete on August 29, 2009. 
The Dumbarton Bridge, located in southern San Francisco Bay (Bay), was 
designed in the late 1970s based on the design standards that Caltrans 
established in 1971. Since that time, upgraded standards have been 
issued, particularly Caltrans' Seismic Design Criteria of 1999, of 
which the bridge does not meet. The Dumbarton Seismic Retrofit Project 
would provide a seismic upgrade of the Dumbarton Bridge to meet these 
current requirements.
    To allow access to shallow water (<10 ft) piers which need to be 
retrofitted, a temporary trestle supported by 24-inch hollow steel 
piles must be installed; a barge will allow access to piers in deeper 
water. In addition, cofferdams will be created using sheet piles to 
pour concrete collars around pre-existing piles to strengthen the 
piers. Installation of the temporary steel and sheet piles necessitates 
use of mainly vibratory hammers, but an impact hammer may be used for 
proofing up to two piles each day. The entire retrofit project is 
expected to take three years to complete; however, installation of the 
temporary piles is expected to take approximately 4 months and 
installation of sheet piles could take one year. All other work would 
be on-land. Because pile driving has the potential to disturb marine 
mammals in the area, Caltrans is requesting a one-year authorization to 
harass marine mammals incidental to this specified activity.

Construction Process

    The existing bridge span is approximately 8,600 ft (2,261 m) long 
and 85 ft (26 m) wide and provides access for approximately 80,000 
trips across the Bay between Alameda and San Mateo counties each day. 
The bridge consists of three structural types in five sections. The 
five sections include a main channel crossing at the center of the 
bridge, two approach sections (one each on the eastern and western 
sides), and two trestle structures (one on each end) that anchor the 
bridge (see Figure 1-2 in the application). Seismic retrofit activities 
would take place on all five sections of the bridge; however, only a 
portion of the project contains the activity which could result in the 
take of marine mammals: pile driving.
    Retrofitting itself involves strengthening connections between 
columns, pedestals, and pile caps which does not involve introducing 
intense sound production. Pile driving; however, does result in 
elevated in-air and in-water noise levels; therefore, this activity may 
impact marine mammals in the vicinity of the operating pile driver. It 
should be noted that some of the specifics of the project (e.g., 
percent of vibratory pile driving vs. impact pile driving) have been 
altered from description in the MMPA IHA application as a result of 
NMFS' recommendations. Therefore, the following description accurately 
describes the pile driving process Caltrans currently proposes.

Approach Sections

    The approach sections adjacent to the main channel bridge crossing 
are supported by a series of piers. The western approach section is 
2,580 ft (786 m) long and extends from Pier 1 to Pier 15. The eastern 
approach section is 2,600 ft (792 m) long, extending from Pier 32 to 
Pier 44. Seismic upgrades on these piers include retrofitting the 
existing piers through strengthening the connection between the 
columns, pedestals and pile caps with the installation of a reinforced 
concrete collar. In order to perform the concrete work, temporary work 
trestles and cofferdams will be installed for work access and to 
dewater the areas around the piers. In addition, trestles would 
facilitate removal of the adjacent Ravenswood Pier. Upon completion of 
the Dumbarton Bridge Seismic Retrofit Project, temporary trestles, 
cofferdams, barges and other falsework will be removed from the area.
    Caltrans estimates approximately 1,000 temporary hollow steel pipe 
piles, with a maximum diameter of 24-inches, will be needed to 
construct the trestles. Piles associated with the temporary trestles 
would only be installed in water less than 10 ft in depth and would be 
driven out of water whenever possible (e.g., on the mudbanks at low 
tide). The piles will be inserted in rows of three, with approximately 
25 ft (7.6 m) between each row. Temporary trestle superstructure 
(decking) will then be constructed atop the support piles. An 
additional 16 piles will extend from the temporary work trestle to 
surround each

[[Page 63726]]

existing support pier to allow construction around all sides of the 
pier. All temporary trestles will be less than 25 ft wide. Caltrans 
will install a maximum of 12 piles per day (six on each side of the 
Bay) using mainly a vibratory pile driving method. Vibration 
installation will start and continue for 5 minutes followed by an 
approximate 30-minute delay. The second pile will be vibrated into 
place for 5 minutes. Bent members and spans will then be erected, 
possibly taking 2 to 3 hours before the second set of piles is vibrated 
into place.
    In total, vibratory pile driving would not occur for more than two 
hours per day. In order to verify load capacity of the temporary piles, 
approximately one in eight piles (12 percent) will be ``tapped'' with 
an impact hammer for proofing. Each pile to be tested would be tapped 
for a total of 10-1 5 seconds. No more than two piles per day would 
need testing. Vibratory pile driving may occur at any time during the 
year; however, when ESA-listed steelhead may be present (December 1st 
to June 14th), the re-tap or use of an impact hammer is restricted to 
low-tide periods only to minimize impact to salmonids.
    Caltrans estimates construction of the temporary trestles will take 
approximately three weeks total. The temporary piles are expected to 
remain in the Bay for a period of three years and would be removed 
after retrofitting is complete. No trestle will be constructed in the 
main channel as all work in the channel will take place from a 
stationary barge.
    In addition to the trestle, cofferdams will be created around piles 
facilitate installation on the concrete collars which will strengthen 
the bridge. Cofferdams will be created around 20 piers (piers 5-15 and 
32-40) by vibrating steel sheet piles into place around each pier. Once 
the sheet piles are in place (2 ft from the edges of the existing piles 
caps and driven to approximately 15 ft) the space between the sheet 
piles and the piers would be dewatered. Once drained, a concrete collar 
providing seismic support will be poured in the cofferdam. Upon 
hardening, the sheet piles will be removed.

Existing Trestle Structures

    Caltrans would also retrofit existing trestle structures on land at 
the east and west ends of the bridge to provide lateral strengthening. 
Each trestle is 600 ft long. To accomplish this, Caltrans would install 
of a total of 28 permanent 48-inch steel pipe piles close to the waters 
edge but not in the water; distance to the water is dependent upon the 
tidal stage. Fourteen of these piles would be placed on already paved 
road and fourteen would be placed into weedy ruderal vegetation 
enclosed by parking islands and the trestle itself. A maximum of four 
piles per day would be installed requiring 30-minutes driving time. 
These piles would be installed between October 1 and November 30 to 
avoid salmon migration periods. Although these piles would be driven on 
land, noise from impact hammering could propagate into the water from 
vibration and through the air-water interface (see Table 1 below). 
Therefore, NMFS considered impacts of land based pile driving when 
assessing impacts to marine mammals.

Main Channel Crossing

    The main channel crossing is approximately 3,000 ft (914 m) long 
and spans the South Bay channel, which is about 2,500 ft (762 m) wide, 
extending from piers 16-31. No in-water construction will occur for 
retrofitting the main channel crossing. Barges and small marine vessels 
will be used to transport equipment to the main channel crossing. 
Structural improvements to the bridge hinges located within the 
superstructure (roadway bed), and on substructure (such as pedestals 
located above the pile caps, and on bent caps located immediately below 
the superstructure) will occur from the existing roadway or from atop 
barges. All tugs pushing or supporting barge placement are slow moving 
or, once in place, stationary. Caltrans would not actively approach any 
marine mammals, in accordance with NMFS viewing guidelines, in tugs or 
any other support vessels.
    Some components of the project, as described in the application 
(e.g., creation of a construction of a barrier to keep high-tide water 
from encroaching onto the bridge, creation of a drainage system, and 
the removal of Ravenswood pier), would not involve introduction of 
noise into the environment or substantial marine mammal habitat related 
impacts and are not expected to harass marine mammals. Therefore, NMFS 
has preliminary determined that these specified activities do not 
warrant an authorization to incidentally harass marine mammals, and 
they will not be discussed further here. For more information on NMFS' 
determinations of these activities on ESA-listed salmonids, please 
refer to the August 10, 2009 Biological Opinion issued to Caltrans for 
this action.

Action Area

    The Dumbarton Bridge Project site, including the area around the 
bridge piers and the area necessary to accommodate construction-related 
equipment such as work barges and cranes, is located in the south Bay, 
between Fremont and Menlo Park in East Palo Alto, California (see 
Figure 1-1 in application). The bridge is a major east/west connector 
between Interstate 880 in Alameda County and U.S. Highway 101 in San 
Mateo County. It is surrounded by open bay, salt ponds, salt marshes, 
mudflats, vernal pools and, on the eastern end, the Don Edwards San 
Francisco Bay National Wildlife Refuge. These habitats are home to a 
variety of important species, including protected birds, fish, and 
marine mammals, that are protected by a variety of environmental 
regulations. At high tide, water depth on the surrounding flats ranges 
from 1-10 ft (0.3-3 m), depending on local conditions. At low tide, the 
flats are exposed, hence pile driving may not always be occurring in-
water.

Affected Environment

    At least 35 marine mammal species can be found off the coast of 
California; however, few venture into the Bay and only Pacific harbor 
seals and California sea lions inhabit the southern portion of the Bay 
regularly. Gray whales are sighted in the Bay during their yearly 
migration, though most sightings tend to occur in the central Bay. 
Humpback whales (Megaptera noveangliae), while sometimes present in the 
central Bay, are rare in the south and are not expected to be present 
within the action area. Therefore, humpback whales will not be 
considered further in this analysis and no take authorization is 
requested or proposed for this action.

Harbor Seals

    The Pacific harbor seal impacted by this project belong to the 
California stock which is not listed as depleted under the MMPA or 
endangered or threatened under the Endangered Species Act (ESA). The 
most current stock assessment report estimates a population of 34,233 
(NMFS 2005). More site specific, a recent marine mammal study conducted 
before and during seismic retrofit work on the Richmond San Rafael 
Bridge (RSRB) in the northern Bay included extensive monitoring of 
marine mammals at points throughout the Bay, including the Central and 
South Bay areas. This study concluded that at least 500 seals populate 
the Bay, an estimate which closely agrees with previous seal counts, 
which ranged from 524 to 641 seals from 1987 to 1999 (Goals Project 
2000).
    Harbor seals generally do not migrate and display year-round site 
fidelity,

[[Page 63727]]

though they have been known to swim several hundred miles to find food 
or suitable habitat. Seals within the Bay engage in limited seasonal 
movements associated with foraging and breeding activities (Kopec and 
Harvey 1995), and seals in the South Bay may make daily northward 
foraging excursions.
    Although generally solitary in the water, harbor seals come ashore 
at communal sites known as ``haul-outs,'' which are used for resting, 
thermoregulation, birthing, and nursing pups (see figure 4-1. in the 
application for haul-out sites in the Bay). Haul-out locations are 
relatively consistent from year to year (Kopec and Harvey, 1995), and 
females have been recorded returning to their own natal haul-out when 
breeding (Green et al., 2006). Bay harbor seals haul out in groups 
ranging in size from a few individuals to several hundred seals. Bay 
haul-out sites that support some of the largest concentrations of seals 
include Mowry Slough (located approximately 4 miles south of the 
project site), Corte Madera Marsh, Castro Rocks, and Yerba Buena Island 
in the Central Bay (all approximately 25 to 35 miles north of the 
project site). The haul-out site closest to the bridge is at Newark 
Slough, approximately 2.7 miles south of the project site, near the 
junction of Newark Slough and Plummer Creek. Although the Newark Slough 
haul-out is a known pupping site, relatively few harbor seals use the 
site. Both Newark and Mowry sloughs are used by seals continuously 
year-round but have higher numbers of seals during pupping and molting 
seasons (spring and summer). Because of the location of these two sites 
are on the southern side of a spit of land, the bridge is not visible 
from these locations. Hence, construction activities would not be 
visible to seals at the haul-outs. Other South Bay haul-outs include 
Coyote Point, Seal Slough, Belmont Slough, Bair Island, Corkscrew 
Slough, Greco Island, Ravenswood Point, Hayward Slough, Dumbarton 
Point, Calaveras Point, Drawbridge, and Guadalupe Slough (Goals 
Project, 2000). Caltrans' IHA application contains a map with locations 
of these haul-outs relative to the Dumbarton Bridge.
    In addition to Newark and Mowry haul-outs, there is one foraging 
area identified close to the bridge. The most numerous prey items 
identified in harbor seal fecal samples from haul-out sites in the Bay 
include yellowfin goby (Acanthogobius flavimanus), northern anchovy 
(Engraulis mordax), Pacific herring (Clupea harengus pallasi), staghorn 
sculpin (Leptocottus armatus), plainfin midshipman (Porichthys 
notatus), and white croaker (Genyonemus lineatas) (Harvey and Torok, 
1994).
    Pinnipeds produce a wide range of hearing social signals, most 
occurring at relatively low frequencies (Southall et al., 2007), 
suggesting hearing is keenest at these frequencies. Pinnipeds 
communicate acoustically both on land and in the water suggesting they 
possess amphibious hearing and have difference hearing capabilities 
dependant upon the media (air or water). Based on numerous studies, as 
summarized in Southall et al. (2007), pinnipeds are more sensitive to a 
broader range of sound frequencies in water than in air. In-water, 
pinnipeds can hear frequencies from 75 Hz to 75 kHz. In-air, the lower 
limit remains at 75 Hz but the highest audible frequencies are only 
around 30 kHz (Southall, et al., 2007).

California Sea Lions

    California sea lions are endemic to the Northern Pacific Ocean, 
breeding in southern California and along the Channel Islands during 
the spring. They are not listed as depleted under the MMPA or as 
endangered or threatened under the ESA. The most current stock 
assessment report estimates there are approximately 238,000 sea lions 
in the U.S (NMFS, 2007). In the Bay, sea lions haul out primarily on 
floating docks at Pier 39 in the Fisherman's Wharf area of the San 
Francisco Marina and on buoys and similar structures throughout the 
Bay. They are seen swimming mainly off the San Francisco and Marin 
shorelines within the Bay but may occasionally enter the South Bay area 
to forage. Although not a frequent visitor to the southern portion of 
the Bay, sea lions have been sighted traveling through the area, most 
likely for foraging opportunities. Their diet consists primarily of 
pacific herring, northern anchovy, and sardines. Sea lions rarely haul-
out in the southern Bay.

Gray Whales

    Gray whales, a large baleen whale, potentially affected by the 
proposed project belong to the Eastern North Pacific stock. This stock 
is not listed as depleted under the MMPA and was de-listed from the ESA 
in 1994 (59 FR 31094). Currently, this stock's population is estimated 
at approximately 18,813 individuals (NMFS, 2008). Eastern gray whales 
migrate each year along the west coast of North America, feeding in 
northern waters primarily off Alaska during the summer before heading 
to breeding and calving grounds off Mexico over the winter. Their 
migrations take them past the San Francisco coast from December through 
February, heading south, and again from mid-February through July, 
heading north. During the migration, gray whales will occasionally 
enter rivers and bays (such as the Bay) along the coast but not in high 
numbers. Individual whales may use the shallow Bay waters for foraging, 
or they may simply be off course. Gray whales are the only baleen 
whales known to feed on the sea floor, where they scoop up bottom 
sediments to filter out benthic crustaceans, mollusks, and worms.
    No acoustical measurements of gray whale hearing have been 
published. However, gray whales likely hear sounds in the 50 to 500 Hz 
range, and baleen whale sounds, though mostly below 1 kHz, are common 
up to 8 kHz. However, the low and high end limits of hearing for gray 
whales are unknown (Richardson et al. 1995).

Impacts to Marine Mammals

    As stated, noise from pile driving has the potential to harass 
marine mammals present in the action area. Sound is a physical 
phenomenon consisting of minute vibrations that travel through a 
medium, such as air or water. Sound is generally characterized by 
several variables, including frequency and sound level. Frequency 
describes the sound's pitch and is measured in hertz (Hz) or kilohertz 
(kHz), while sound level describes the sound's loudness and is measured 
in decibels (dB). Sound level increases or decreases exponentially with 
each dB of change. For example, 10-dB yields a sound level 10 times 
more intense than 1 dB, while a 20 dB level equates to 100 times more 
intense, and a 30 dB level is 1,000 times more intense. Sound levels 
are compared to a reference sound pressure (micro-Pascal) to identify 
the medium. For air and water, these reference pressures are ``re: 20 
microPa'' and ``re: 1 microPa'', respectively. All underwater noise 
levels presented here are quantified in decibels relative to 1 microPa 
(dB, re: 1 microPa) unless otherwise noted.
    Marine mammals are continually exposed to many sources of sound. 
Naturally occurring sounds such as lightning, rain, sub-sea 
earthquakes, and biological sounds (e.g., snapping shrimp, whale songs) 
are ubiquitous throughout the world's oceans. Marine mammals produce 
sounds in various contexts and use sound for various biological 
functions including, but not limited to, (1) social interactions; (2) 
foraging; (3) orientation; and (4) predator detection. Interference 
with producing or receiving these sounds may result in adverse impacts. 
Audible

[[Page 63728]]

distance, or received levels (RLs) will depend on the nature of the 
sound source, ambient noise conditions, and the sensitivity of the 
receptor to the sound (Richardson et al., 1995). Type and significance 
of marine mammal reactions to noise are likely to dependent on a 
variety of factors including, but not limited to, the behavioral state 
(e.g., feeding, traveling, etc.) of the animal at the time it receives 
the stimulus, frequency of the sound, distance from the source, and the 
level of the sound relative to ambient conditions (Southall et al., 
2007).

Hearing Impairment

    Temporary or permanent hearing impairment is a possibility when 
marine mammals are exposed to very loud sounds. Hearing impairment is 
measured in two forms: temporary threshold shift (TTS) and permanent 
threshold shift (PTS). There are no empirical data for onset of PTS in 
any marine mammal; therefore, PTS- onset must be estimated from TTS-
onset measurements and from the rate of TTS growth with increasing 
exposure levels above the level eliciting TTS-onset. PTS is presumed to 
be likely if the hearing threshold is reduced by [gteqt] 40 dB (i.e., 
40 dB of TTS). Due to proposed mitigation measures and source levels, 
NMFS does not expect that marine mammals will be exposed to levels that 
could elicit PTS; therefore, it will not be discussed further.

Temporary Threshold Shift (TTS)

    TTS is the mildest form of hearing impairment that can occur during 
exposure to a loud sound (Kryter, 1985). While experiencing TTS, the 
hearing threshold rises and a sound must be louder in order to be 
heard. TTS can last from minutes or hours to, in cases of strong TTS, 
days. For sound exposures at or somewhat above the TTS-onset threshold, 
hearing sensitivity recovers rapidly after exposure to the noise ends. 
Few data on sound levels and durations necessary to elicit mild TTS 
have been obtained for marine mammals. Southall et al. (2007) considers 
a 6 dB TTS (i.e., baseline thresholds are elevated by 6 dB) sufficient 
to be recognized as an unequivocal deviation and thus a sufficient 
definition of TTS-onset. Because it is non-injurious, NMFS considers 
TTS as Level B harassment that is mediated by physiological effects on 
the auditory system; however, NMFS does not consider onset TTS to be 
the lowest level at which Level B harassment may occur.
    Sound exposures that elicit TTS in pinnipeds underwater have been 
measured in harbor seals, California sea lions, and northern elephant 
seals from broadband or octaveband (OBN) non-pulse noise ranging from 
approximately 12 minutes to several hours and pulse noise (Kastak and 
Schusterman, 1996; Finneran et al., 2003; Kastak et al., 1999; Kastak 
et al., 2005). Collectively, Kastak et al. (2005) analyzed these data 
to indicate that in the harbor seal, a TTS of ca. 6 dB occurred with 25 
minute exposure to 2.5 kHz OBN with SPL of 152 dB re:1 microPa; the 
California sea lion showed TTS-onset at 174 dB re: 1 microPa (as 
summarized in Southall et al., 2007). Underwater TTS experiments 
involving exposure to pulse noise is limited to a single study. 
Finneran et al. (2003) found no measurable TTS when two California sea 
lions were exposed to sounds up to 183 dB re: 1 microPa (peak-to-peak).
    There are limited data available on the effects of non-pulse noise 
(e.g., vibratory pile driving) on pinnipeds in-water; however, field 
and captive studies to date collectively suggest that pinnipeds do not 
strongly react to exposures between 90-140 dB re: 1 microPa; no data 
exist from exposures at higher levels. Jacobs and Terhune (2002) 
observed wild harbor seal reactions to high frequency acoustic 
harassment devices (ADH) around nine sites. Seals came within 44 m of 
the active ADH and failed to demonstrate any behavioral response when 
received SPLs were estimated at 120-130 dB. In a captive study 
(Kastelein, 2006), a group of seals were collectively subjected to data 
collection and communication network (ACME) non-pulse sounds at 8-16 
kHz. Exposures between 80-107 dB did not induce strong behavioral 
responses; however, a single observation at 100-110 dB indicated an 
avoidance response at this level. The group returned to baseline 
conditions shortly following exposure. Southall et al. (2007) notes 
contextual differences between these two studies noting that the 
captive animals were not reinforced with food for remaining in the 
noise fields, whereas free-ranging subjects may have been more tolerant 
of exposures because of motivation to return to a safe location or 
approach enclosures holding prey items. While most of the pile driving 
will be vibratory, a small portion of piles will be driven using an 
impact hammer (pulse noise). Southall et al. (2007) reviewed relevant 
data from studies involving pinnipeds exposed to pulse noise and 
concluded that exposures to 150 to 180 dB generally have limited 
potential to induce avoidance behavior.
    Seals and sea lions exposed to threshold level sounds in water (160 
dB for pulse sounds (e.g., impact pile driving) or 120 dB for non-pulse 
sounds (e.g., vibratory pile driving)) may elicit temporary avoidance 
behavior around the bridge which may affect the routes of seals under 
the bridge or temporarily inhibit them from foraging near the bridge. 
However, limiting pile driving to two hours per day would allow for 
minimal disruption of harbor seal foraging or dispersal habitat under 
or near the bridge. Even more limited impacts to foraging or haul-out 
for sea lions are anticipated because very few sea lions use the South 
Bay for foraging and no known sea lion haul-outs exist in the South 
Bay. The bridge area is not a regular or commonly used foraging or 
calving area for gray whales; therefore, project construction 
activities are not expected to affect whale foraging or reproductive 
success within the Bay.
    The individual piers on the bridge which are to be retrofitted are 
spaced at approximately 100-350-ft (30-106 m) intervals. The rows of 
piles for the temporary construction trestles will be spaced at 25-ft 
(7.6 m) intervals. The temporary trestle will reach bayward to the 10-
ft (3 m) depth contour with the top of the trestle approximately seven 
feet above sea level. The temporary trestle will not span the main 
channel, which remains open, allowing passage of marine mammals through 
the project area. Therefore, the construction work will not present any 
physical barrier to marine mammals that may move between the haul-out 
sites and foraging areas.
    Hauled-out seals are vulnerable to stresses caused by human 
disturbance, especially during pupping and molting seasons. Studies 
have shown seals may react negatively to humans coming within 300 to 
570 feet (Green et al., 2006) and may temporarily abandon their haul-
outs or experience reduced reproductive success (Calambokidis et al., 
1979). Construction-related impacts to seals in the form of alert and 
flush disturbances were recorded during the Richmond San Rafael Bridge 
(RSRB) monitoring (Green et al., 2006). Seals hauled out at Castro 
Rocks, located 82 to 280 feet from the RSRB, were disturbed by various 
construction-related activities, including noise and boating activity. 
However, during the pile installation demonstration project (PIDP) for 
the seismic retrofit of the East Span of the Bay Bridge, seals at the 
Yerba Buena Island haul-out initially became alerted when at a distance 
of approximately 0.94 miles, but quickly became acclimatized (Parsons 
Brinckerhoff, 2001).
    Hauled-out seals at Newark Slough (the closest haul-out located 2.7 
miles south of the bridge) or other South Bay

[[Page 63729]]

haul-outs are not expected to be affected by project-related 
activities. Support vessel activities would be primarily north of or 
adjacent to the Dumbarton Bridge, and pile driving would only occur at 
the bridge. The in-air harassment threshold (90 dB re: 20 microPa) 
distance for harbor seals from pile driving is not expected to reach 
more than 800 ft (244 m). Given the distance to the closest haul-out 
(Newark Slough) is 2.7 miles away, NMFS does not anticipate seals on 
haul-outs would be affected as a result of the project.

Proposed Mitigation

    In order to issue an IHA under Section 101(a)(5)(D) of the MMPA, 
NMFS must set forth the permissible methods of taking pursuant to such 
activity, and other means of effecting the least practicable adverse 
impact on such species or stock and its habitat, paying particular 
attention to rookeries, mating grounds, and areas of similar 
significance, and on the availability of such species or stock for 
taking for certain subsistence uses. Caltrans has proposed mitigation 
both in their application and supplemental communication to reduce 
impact to environmental resources. Measures set in place to protect 
birds and fish (e.g., using the vibratory hammer at all times except 
for load bearing tests) also protect marine mammals. The following 
proposed mitigation measures are designed to eliminate potential for 
injury and reduce harassment levels to marine mammals.

Limited use of Impact Hammer

    As a result of Section 7 consultation discussions with NMFS (to 
reduce impacts to ESA-listed fish species), Caltrans has agreed to 
drive all temporary piles with a vibratory hammer with the exception of 
one pile per day being ``proofed'' with an impact hammer which has a 
higher source level. Proofing requires approximately 20 blows per pile 
which equates to approximately 15-20 seconds of impact hammering per 
day. As a result of Section 7 consultation, Caltrans would limit 
proofing piles during low tide only, essentially out-of-water on the 
mudbanks, when ESA-listed steelhead salmon are present (December 1 to 
June 14).

Establishment of safety and zones and shut down requirements

    Although the isopleths to the 190dB and 180dB harassment 
thresholds, are modeled to be within 220 ft (67 m) of the pile hammer 
(see Table 1), Caltrans would shut down or delay commencement of pile 
driving should a marine mammal come within or approach 250 ft (76m) of 
the pile being driven. The aforementioned threshold levels are based on 
an assumption that exposure to lower received levels will not injure 
these animals or impair their hearing abilities, but that higher 
received levels might have such effects. It should be understood that 
marine mammals inside these safety zones will not necessarily be 
injured or seriously injured or killed as these zones were established 
prior to the current understanding that significantly higher levels of 
impulse sounds would be required before injury or mortality could occur 
(see Southall et al., 2007).
    Soft start to pile driving activities
    A ``soft start'' technique will be used at the beginning of each 
pile installation to allow any marine mammal that may be in the 
immediate area to leave before impact piling reaches full energy. The 
soft start requires contractors to initiate noise from vibratory 
hammers for 15 seconds at reduced energy followed by 1-minute waiting 
period. The procedure will be repeated two additional times. Due to the 
short duration of impact pile driving (20 seconds), general ramp-up 
requirement for impact pile driving do not apply as it would actually 
increase the duration of noise emitted into the environment and 
monitoring should effectively detect marine mammals within or near the 
designated safety zone of 250 ft (76 m). If any marine mammal is 
sighted within or approaching the safety zone prior to pile-driving, 
Caltrans will delay pile-driving until the animal has moved outside and 
on a path away from such zone or after 15 minutes have elapsed since 
the last sighting of the marine mammal.
    NMFS has carefully evaluated the applicant's proposed mitigation 
measures and considered a range of other measures in the context of 
ensuring that NMFS prescribes the means of affecting the least 
practicable adverse impact on the affected marine mammal species and 
stocks and their habitat. Our evaluation of potential measures included 
consideration of the following factors in relation to one another: (1) 
the manner in which, and the degree to which, the successful 
implementation of the measure is expected to minimize adverse impacts 
to marine mammals; (2) the proven or likely efficacy of the specific 
measure to minimize adverse impacts as planned; and (3) the 
practicability of the measure for applicant implementation, including 
consideration of personnel safety and practicality of implementation.
    Based on our evaluation of the applicant's proposed measures, as 
well as other measures considered, NMFS has preliminarily determined 
that the proposed mitigation measures provide the means of effecting 
the least practicable adverse impacts on marine mammals species or 
stocks and their habitat, paying particular attention to rookeries, 
mating grounds, and areas of similar significance.

Proposed Monitoring and Reporting

    In order to issue an IHA for an activity, Section 101(a)(5)(D) of 
the MMPA states that NMFS must set forth ``requirements pertaining to 
the monitoring and reporting of such taking''. The MMPA implementing 
regulations at 50 CFR 216.104 (a)(13) indicate that requests for IHAs 
must include the suggested means of accomplishing the necessary 
monitoring and reporting that will result in increased knowledge of the 
species and of the level of taking or impacts on populations of marine 
mammals that are expected to be present.

Visual Monitoring

    At least one week prior to the start of construction, the protected 
species observers (PSOs), trained in detection and identification of 
marine mammals, will conduct a survey effort in order to establish 
baseline data of marine mammal use in the project area. This effort 
will consist of 12 hours of monitoring during the work window that will 
be used during construction (0700 to 1900 hrs).
    Safety zone monitoring will be conducted during all active pile 
driving. Modeling suggests the 190dB and 180dB isopleths are located 60 
ft (18 m) and 220 ft (67 m) from steel piles being driving with an 
impact hammer and even less so for vibratory pile driving. As a 
conservative measure, Caltrans is proposing a 250 ft (76 m) safety zone 
(i.e., mandatory shut down zone) until acoustic measurements can be 
made to confirm the distances identified in Table 1 above are accurate. 
Should acoustic studies deem these distances are not accurate, they 
will be adjusted accordingly. Pile driving will not begin until the 
safety zone is clear of marine mammals and will be stopped in the event 
that marine mammals enter the safety zone. SPOs will begin monitoring 
at least 30 minutes prior to the commencement of pile driving. Data 
collection will consist of a count of all pinnipeds and cetaceans by 
species, a description of behavior (based on the Richmond Bridge Harbor 
Seal Survey classification system), sex and age class, if possible, 
location, direction of movement, type of construction that is 
occurring, time that pile driving begins

[[Page 63730]]

and ends, any acoustic or visual disturbance, and time of the 
observation. Environmental conditions such as wind speed, wind 
direction, visibility, temperature, tide level, current, and sea state 
(described using the standard Beaufort sea scale) would also be 
recorded.
    Monitoring of marine mammals will be conducted using high quality 
binoculars (e.g., Zeiss, 10 x 42 power). When possible, digital video 
or 35 mm still cameras will also be used to document the behavior and 
response of marine mammals to construction activities or other 
disturbances. Each monitor will have a radio for contact with other 
researchers or work crews if necessary, a GPS unit for determining 
observation location, and an electronic range finder to determine 
distance to marine mammals, boats, buoys and construction equipment. 
Most likely observers will conduct the monitoring from the Dumbarton 
Bridge surface or catwalks, providing a high vantage point for the 
observer; however, should a small vessel be used to monitor for marine 
mammals, PSOs will remain 50 yards from swimming pinnipeds in 
accordance with NMFS marine mammal viewing guidelines (http://swr.nmfs.noaa.gov/psd/rookeryhaulouts/CASEALVIEWBROCHURE.pdf). This 
will prevent additional harassment to pinnipeds from the vessel.

Acoustic Monitoring

    Hydroacoustic monitoring would be conducted by a qualified monitor 
during pile-driving activities when piles are being driven in water 
greater than 3 feet in depth. Details would be developed during work 
plan preparation, but might include monitoring one pile in every set of 
3 piles during installation of the temporary trestles. A reference 
location would be established at the estimated 180 dB contour (distance 
of 230 feet from the pile driving). Sound measurements would be taken 
at the reference location and at locations every 20 feet until the 180 
dB level is found. Measurements would be taken at two depths: one in 
mid water column and one near the bottom but at least 3 feet above the 
bottom, unless obstructions such as land force a variation in depth or 
number of measurements. Marine mammal safety zones would be adjusted to 
maintain a safety zone outside of 180 dB, according to the results of 
this monitoring.

Reporting

    Data collection will consist of a count of all pinnipeds and 
cetaceans by species, a description of behavior (based on the Richmond 
Bridge Harbor Seal Survey classification system), sex and age class, if 
possible, location, direction of movement, type of construction that is 
occurring, time that pile driving begins and ends, any acoustic or 
visual disturbance, and time of the observation. Environmental 
conditions such as wind speed, wind direction, visibility, temperature, 
tide level, current, and sea state (described using the standard 
Beaufort sea scale) would also be recorded. Monitoring reports 
including the above listed information would be submitted to NMFS 
weekly. In addition, a final report summarizing all marine mammal 
monitoring and construction activities will be submitted to NMFS 90 
days after the IHA expires.

Estimated Take by Harassment

    NMFS typically proposes threshold sound levels to establish 
appropriate mitigation. Current NMFS practice regarding exposure of 
marine mammals to anthropogenic noise is that in order to avoid injury 
of marine mammals (e.g., PTS), cetaceans and pinnipeds should not be 
exposed to impulsive sounds of 180 and 190 dB rms or above, 
respectively. This level is considered precautionary as it is likely 
that more intense sounds would be required before injury would actually 
occur (Southall et al., 2007). As such, Caltrans has proposed safety 
zones based on hydroacoustical modeling for the pile sizes and type of 
hammers used for the Dumbarton Bridge project and water depth. The 
model simulates spherical spreading and uses a transmission constant of 
15. Potential for behavioral harassment (Level B) is considered to have 
occurred when marine mammals are exposed to sounds at or above 160 dB 
rms for impulse sounds (e.g., impact pile driving) and 120dB rms for 
non-pulse noise (e.g., vibratory pile driving), but below the 
aforementioned thresholds. These levels are considered precautionary. 
Estimated distances to NMFS current threshold sound levels from pile 
driving during the proposed action are outlined in Table 1 below (see 
Chapter 7 and Appendix A in the application for further detail how 
these distances were derived).

                                Table 1: Modeled underwater distances to NMFS' marine mammal harassment threshold levels.
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                            Calculated Distance to Criteria Thresholds\1\
                Driving Location                   Pile Type    Hammer Type ----------------------------------------------------------------------------
                                                                                190 dB           180 dB              160 dB                120 dB
--------------------------------------------------------------------------------------------------------------------------------------------------------
Water                                            24 `` steel        Impact   60 ft (18m)       220 ft (67m)     3,300 ft (1005m)                    n/a
-------------------------------------------------------------------------------------------
Water                                            24 `` steel     Vibratory           n/a         10 ft (3m)                  n/a    3.2 miles (5.14 km)
-------------------------------------------------------------------------------------------
Water                                             Sheet pile     Vibratory           n/a        5 ft (1.5m)                  n/a   1.4 miles (2.25 kms)
-------------------------------------------------------------------------------------------
Land                                              48'' steel        Impact           n/a    100 ft (30.5 m)      1,475 ft (500m)                    n/a
-------------------------------------------------------------------------------------------
Land                                             Steel piles     Vibratory             0                  0                    0        150 ft (45.7 m)
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\dB referenced to 1 microPa in water and to 20 microPa on land.

    Current NMFS practice regarding in-air exposure of pinnipeds to 
noise generated from human activity is that the onset of Level B 
harassment for harbor seals and all other pinnipeds is 90 dB and 100 dB 
re: 20 micoPa, respectively. In-air noise calculations from pile 
driving for this project predict that noise levels will be reduced to 
approximately 83 dB re: 20 microPa at 800 m. Harbor seals or California 
sea lions are not known to haul-out this close to the bridge (the 
closest haul-out is 2.7 miles away); therefore, pinnipeds at haulouts 
are not expected to be affected from in-air pile driving noise.
    The population of harbor seals in the South Bay is estimated at 
approximately 300. Specific movements of the seals are not well 
understood; however, based on marine mammal surveys, approximately half 
the population passes through the action area each day some of which 
may be younger animals given the proximity to the haul-outs. Assuming 
equal distribution of seal movement throughout the day, approximately 4

[[Page 63731]]

seals could pass through the area at any given hour (between zero and 
four seals have been sighted per hour at the northern East Span Bay 
Bridge project location). Pile driving is expected to last a maximum of 
two hours per day; therefore eight seals per day could be exposed to 
harassment level noise for approximately 4 months. Therefore, Caltrans 
is requesting the take, by Level B harassment only, 1,120 harbor seals.
    Because there are no California sea lion haul-out sites in the 
South Bay, sea lions are expected to be incidental visitors to the 
area. Given the limited sightings in the South Bay and the distance to 
the nearest haul-out, Caltrans is requesting the take of 10 adult sea 
lions. Similarly, gray whales are rare in the southern portion of the 
Bay however they may be present resulting in Caltrans requesting 
authorization to harass two gray whales per year incidental to the 
proposed action.

Preliminary Determination

    Based on the analysis contained herein of the likely effects of the 
specified activity on marine mammals and their habitat, and taking into 
consideration the implementation of the mitigation and monitoring 
measures, NMFS preliminarily finds that pile driving associated with 
the Dumbarton Bridge Seismic Retrofit Project will result in the 
incidental take of small numbers of marine mammals, by Level B 
harassment only, and that the total taking from will have a negligible 
impact on the affected species or stocks. No subsistence hunting of 
marine mammals occur in the region; therefore, no impact on the 
availability of a species or stock for subsistence use would occur.

Endangered Species Act (ESA)

    On January 12, 2009, NMFS received a request from the Federal 
Highway Administration (FHWA) to initiate consultation under section 7 
of the ESA on Caltrans' proposed Dumbarton Bridge Seismic Retrofit 
Project as ESA-listed fish are present within the action area. NMFS 
issued a Biological Opinion (BiOp) on Caltran's Dumbarton Bridge 
Seismic Retrofit Project on August, 10, 2009. The BiOp concluded that 
the proposed activities were not likely to jeopardize the continued 
existence of Central California Coast steelhead Distinct Population 
Segment (DPS) or North American green sturgeon DPS and are not likely 
to adversely modify or destroy critical habitat for CCC steelhead DPS.
    NMFS has determined that no ESA listed marine mammal species are 
likely to be affected by the proposed action as none are present within 
the action area; therefore, ESA consultation on issuance of the 
proposed IHA is not warranted.

National Environmental Policy Act (NEPA)

    NOAA Administrative Order Series 216-6, May 20, 1999 (NAO), 
identifies issuance of IHAs as a type of Federal action that may be 
categorically excluded from preparation of an environmental assessment 
or environmental impact statement. In determining whether a categorical 
exclusion (CE) is appropriate for a given IHA, NMFS must consider: (1) 
factors listed in Section 5.05b of the NAO regarding prior analysis for 
the ``same'' action; (2) context and intensity of impacts, as defined 
in 40 CFR 1508.27; and (3) factors listed in Section 5.05c of the NAO 
regarding exceptions to CEs. NMFS has prepared, supplemented, or 
adopted numerous EAs leading to Findings of No Significant Impact 
(FONSIs) for pile driving activities similar to the proposed activity, 
including ones for Caltrans' projects which involved driving larger 
piles in the northern section of the Bay where pinniped and cetacean 
species are more abundant. Based on these previous NEPA analyses and 
the analysis contained within this notice, NMFS has determined that 
issuance of a one-year IHA to Caltrans for the taking, by Level B 
harassment only, incidental to the Dumbarton Bridge Seismic Retrofit 
project does not have the potential to result in any significant 
changes to the human environment. Therefore, the issuance of an IHA to 
Caltrans for the specified activity falls under the category of those 
actions which can be categorically excluded from the need to prepare an 
Environmental Assessment or Environmental Impact Statement.

    Dated: November 19, 2009.
James H. Lecky,
Director, Office of Protected Resources, National Marine Fisheries 
Service.
[FR Doc. E9-28991 Filed 12-3-09; 8:45 am]
BILLING CODE 3510-22-S