[Federal Register Volume 76, Number 24 (Friday, February 4, 2011)]
[Notices]
[Pages 6406-6430]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2011-2530]
[[Page 6406]]
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DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
RIN 0648-XA116
Takes of Marine Mammals Incidental to Specified Activities;
Taking Marine Mammals Incidental to a Pile Replacement Project
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: NMFS has received an application from the U.S. Navy (Navy) for
an Incidental Harassment Authorization (IHA) to take marine mammals, by
harassment, incidental to construction activities as part of a pile
replacement project. Pursuant to the Marine Mammal Protection Act
(MMPA), NMFS is requesting comments on its proposal to issue an IHA to
the Navy to take, by Level B Harassment only, five species of marine
mammals during the specified activity.
DATES: Comments and information must be received no later than March 7,
2011.
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 e-mail 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.
Instructions: All comments received are a part of the public record
and will generally be posted to http://www.nmfs.noaa.gov/pr/permits/incidental.htm without change. All Personal Identifying Information
(e.g., name, address) voluntarily submitted by the commenter may be
publicly accessible. Do not submit Confidential Business Information or
otherwise sensitive or protected information.
A copy of the 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. The Navy has prepared a
draft Environmental Assessment (EA) titled ``Explosives Handling Wharf
1 Pile Replacement Project, Naval Base Kitsap Bangor, Silverdale, WA''.
This associated document, prepared in compliance with the National
Environmental Policy Act (NEPA), is also available at the same Internet
address. Documents cited in this notice may also be viewed, by
appointment, during regular business hours, at the aforementioned
address.
FOR FURTHER INFORMATION CONTACT: Ben Laws, 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.
Authorization for incidental takings shall be granted if NMFS finds
that the taking will have a negligible impact on the species or
stock(s), will not have an unmitigable adverse impact on the
availability of the species or stock(s) for subsistence uses (where
relevant), and if the permissible methods of taking and requirements
pertaining to the mitigation, monitoring and reporting of such takings
are set forth. NMFS has defined ``negligible impact'' in 50 CFR 216.103
as ``* * * an impact resulting from the specified activity that cannot
be reasonably expected to, and is not reasonably likely to, adversely
affect the species or stock through effects on annual rates of
recruitment or survival.''
Section 101(a)(5)(D) of the MMPA established an expedited process
by which citizens of the U.S. can apply for 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. 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].
Summary of Request
NMFS received an application on December 16, 2010 from the Navy for
the taking of marine mammals incidental to pile driving and removal in
association with a pile replacement project in the Hood Canal at Naval
Base Kitsap in Bangor, WA (NBKB). This pile replacement project is
proposed to occur between July 16, 2011 and July 15, 2013. This IHA
would cover only the initial year of this project (July 16, 2011-July
15, 2012), with a subsequent IHA necessary for completion. Pile driving
and removal activities would occur only within a window from July 16-
October 31, with any required impact driving occurring only from July
16-September 30. Six species of marine mammals are known from the
waters surrounding NBKB: Steller sea lions (Eumetopias jubatus),
California sea lions (Zalophus californianus), harbor seals (Phoca
vitulina), killer whales (Orcinus orca), Dall's porpoises (Phocoenoides
dalli), and harbor porpoises (Phocoena phocoena). These species may
occur year-round in the Hood Canal, with the exception of the Steller
sea lion. Steller sea lions are present only from fall to late spring
(November-June), outside of the project's pile driving and removal
window (July 16-October 31). Additionally, while the Southern Resident
killer whale (listed as endangered under the Endangered Species Act
[ESA]) is resident to the inland waters of Washington and British
Columbia, it has not been observed in the Hood Canal in decades and was
therefore excluded from further analysis. Only the five species which
may be present during the project's timeline may be exposed to sound
pressure levels associated with vibratory and impulsive pile driving,
or pneumatic chipping, and will be analyzed in detail in this document.
The Navy proposes to complete necessary repairs and maintenance at
the Explosive Handling Wharf 1 (EHW-1) facility at NBKB as
part of a pile replacement project to restore and maintain the
structural integrity of the wharf and ensure its continued
functionality to support necessary operational requirements. The EHW-1
[[Page 6407]]
facility, constructed in 1977, has been compromised due to the
deterioration of the wharf's existing piling sub-structure. Under the
proposed action, ninety-six 24-in (0.6 m) diameter concrete piles,
thirty-nine 12-in (0.3 m) diameter steel fender piles, and three 24-in
diameter steel fender piles will be removed. In addition, a total of
twenty-eight 30-in (0.8 m) diameter steel pipe piles will be installed
and filled with concrete on the southwest corner of EHW-1. The proposed
action will occur over a two year construction period scheduled to
begin in July 2011, of which the first year would be authorized under
this IHA. All piles will be driven with a vibratory hammer for their
initial embedment depths, and select piles will be impact driven for
their final 10-15 ft (3-4.6 m) for proofing, as necessary. ``Proofing''
involves driving a pile the last few feet into the substrate to
determine the capacity of the pile. The capacity during proofing is
established by measuring the resistance of the pile to a hammer that
has a piston with a known weight and stroke (distance the hammer rises
and falls) so that the energy on top of the pile can be calculated. The
blow count in ``blows per inch'' is measured to verify resistance, and
pile compression capacities are calculated using a known formula. Noise
attenuation measures (i.e., bubble curtain) will be used during all
impact hammer operations. Hydroacoustic monitoring will be performed to
assess effectiveness of noise attenuation measures.
For pile driving activities, the Navy used NMFS-promulgated
thresholds for assessing pile driving and removal impacts (NMFS 2005b,
2009), outlined later in this document. The Navy used recommended
spreading loss formulas (the practical spreading loss equation for
underwater sounds and the spherical spreading loss equation for
airborne sounds) and empirically-measured source levels from other 24-
30 in (0.6-0.8 m) diameter pile driving and removal events to estimate
potential marine mammal exposures. Predicted exposures are outlined
later in this document. The calculations predict that no Level A
harassments would occur associated with pile driving or construction
activities, and that 2,488 Level B harassments may occur during the
pile replacement project from underwater sound. No incidents of
harassment were predicted from airborne sounds associated with pile
driving. Some assumptions (e.g., marine mammal densities) used to
estimate the exposures are conservative, and may overestimate the
potential number of exposures and their severity.
Description of the Specified Activity
NBKB is located on the Hood Canal approximately twenty miles (32
km) west of Seattle, Washington (see Figures 1-1 and 1-2 in the Navy's
application). NBKB provides berthing and support services to Navy
submarines and other fleet assets. The entirety of NBKB, including the
land areas and adjacent water areas in the Hood Canal, is restricted
from general public access. The Navy proposes a pile replacement
project to maintain the structural integrity of EHW-1 and ensure its
continued functionality to support operational requirements of the
TRIDENT submarine program. The proposed actions with the potential to
cause harassment of marine mammals within the waterways adjacent to
NBKB, under the MMPA, are vibratory and impulsive pile driving
operations, and vibratory and pneumatic chipping removal operations,
associated with the pile replacement project. The proposed activities
that would be authorized by this IHA will occur between July 16, 2011
and July 15, 2012. All in-water construction activities within the Hood
Canal are only permitted during July 16-February 15 in order to protect
spawning fish populations. The further restriction of in-water work
window (July 16-October 31) proposed by the Navy avoids the possibility
of incidental harassment of Steller sea lions. The Eastern Distinct
Population Segment (DPS) of Steller sea lions, present in the Hood
Canal outside of this further restriction of the in-water work window,
is listed as threatened under the ESA. Impact pile driving would be
further restricted to the period July 16-September 30, per ESA
consultation with the U.S. Fish and Wildlife Service (USFWS).
As part of the Navy's sea-based strategic deterrence mission, the
Navy Strategic Systems Programs directs research, development,
manufacturing, test, evaluation, and operational support for the
TRIDENT Fleet Ballistic Missile program. Maintenance and development of
necessary facilities for handling of explosive materials is part of
these duties. The proposed action for this IHA request includes the
removal of the fragmentation barrier, walkway, and 138 steel and
concrete piles at EHW-1. Of the piles requiring removal, 96 are 24-in
(0.6 m) diameter hollow pre-cast concrete piles which will be excised
down to the mud line. An additional three 24-in steel fender piles, and
thirty-nine 12-in (0.3 m) steel fender piles, will be extracted using a
vibratory hammer. Also included in the repair work is the installation
of 28 new 30-in (0.8 m) diameter steel pipe piles, the construction of
new cast-in-place pile caps (concrete formwork may be located below
Mean Higher High Water [MHHW]), the installation of the pre-stressed
superstructure, the installation of five sled-mounted cathodic
protection (CP) systems, and the installation or re-installation of
related appurtenances. Sound propagation data will be collected through
hydroacoustic monitoring during pile installation and removal to
support environmental analyses for future repair work that may be
necessary to maintain the EHW-1 facility. The presence of marine
mammals will also be monitored during pile installation and removal.
The EHW-1 pile replacement project has been designed to restore the
structural integrity of the EHW-1 facility which has been compromised
due to the deterioration of the wharf's existing piling sub-structure.
Under the proposed action, ninety-six 24-in (0.6 m) diameter concrete
piles, thirty-nine 12-in (0.3 m) steel fender piles, and three 24-in
diameter steel fender piles will be removed. In addition, a total of
twenty-eight 30-in (0.8 m) diameter steel pipe piles will be installed
and filled with concrete on the southwest corner of EHW-1. The proposed
action will occur over a two year construction period scheduled to
begin in July 2011.
The removal and installation of piles at EHW-1 is broken up into
three components described in detail below and depicted in Figure 1-3
of the Navy's application. The first component of this project would
entail (see Section A on Figure 1-3 pf the Navy's application):
The removal of one 24-in diameter steel fender pile and
its associated fender system components at the outboard support. A
fender pile, typically set beside slips or wharves, guides approaching
vessels and is driven so as to yield slightly when struck in order to
lessen the shock of contact. The fender system components attach the
fender piles to the structure, and are above the water line.
The installation of sixteen 30-in diameter hollow steel
pipe piles (approximately 130 ft [40 m] long), with approximately 100
ft (30 m) of the pile below the Mean Lower Low Water mark.
The construction of two cast-in-place concrete pile caps.
The pile caps would be situated on the tops of the steel piles located
directly beneath the structure (see Figure 1-4 of the Navy's
application for a diagram) and function as a load transfer mechanism
between the superstructure and the piles.
[[Page 6408]]
Concrete formwork may be located below MHHW.
The installation of three sled mounted passive CP systems.
The passive CP system is a metallic rod or anode that is attached to a
metal object to protect it from corrosion. The anode is composed of a
more active metal than that on which it is mounted and is more easily
oxidized, thus corroding first and acting as a barrier against
corrosion for the object to which it is attached. This system would be
banded to the steel piles to prevent metallic surfaces of the wharf
from corroding due to the saline conditions in Hood Canal.
The second component of this project would require (see Section B
in Figure 1-3 of the Navy's application):
The removal of two 24-in diameter steel fender piles at
the main wharf and associated fender system components.
The installation of twelve 30-in diameter hollow steel
pipe piles (approximately 74-122 ft [23-37 m] long). The embedment
depth of the piles would range from 30-50 ft (9-15 m).
The construction of four concrete pile caps.
The installation of a pre-stressed concrete
superstructure. The superstructure is the pre-stressed concrete deck of
the wharf found above, or supported by, the caps or sills, including
the deck, girders, and stringers.
The installation of two sled mounted passive CP systems.
The installation or re-installation of related
appurtenances, the associated parts of the superstructure that connect
the superstructure to the piles. These pieces include components such
as bolts, welded metal hangers and fittings, brackets, etc.
The final component of this project would be (see Section C on
Figure 1-3 of the Navy's application):
The removal of the concrete fragmentation barrier and
walkway, used to get from the Wharf Apron to the Outboard Support.
These structures will likely be removed by cutting the concrete into
sections (potentially three or four in total) using a saw, or other
equipment, and removed using a crane. The crane will lift the sections
from the existing piles and place them on a barge.
The removal of the piles supporting the fragmentation
barrier including:
[cir] Thirty-nine 12-in diameter steel fender piles.
[cir] Ninety-six 24-in diameter hollow pre-cast concrete piles cut
to the mud line (includes 72 at fragmentation barrier, four at walkway,
four at Bent 8 outboard support, and eight at Bents 9 and 10).
Concrete piles would be removed with a pneumatic chipping
hammer or another tool capable of cutting through concrete. A pneumatic
chipping hammer is similar to an electric power tool, such as a
jackhammer, but uses compressed air instead of electricity. The
pneumatic chipping hammer consists of a steel piston that is
reciprocated in a steel barrel by compressed air. On its forward stroke
the piston strikes the end of the chisel. The piston reciprocates at a
rate such that the chisel edge vibrates against the concrete with
enough force to fragment or splinter the pile. The concrete debris
would be captured using debris curtains/sheeting and removed from the
project area.
Pile removal and installation would occur between July 16 and
October 31 during each year of construction, with all impact driving
further restricted to July 16-September 30. The installation of the
concrete pile caps and sled mounted passive CP systems is out-of-water
work, on the tops of the piles themselves or attached to the wharf's
superstructure. In a precautionary measure, these activities would
nonetheless be limited to the in-water work window from July 16 to
February 15--a window established to minimize impacts to fish.
Vibratory driving would be the preferred method for all pile
installation, and would be used for removal of all steel piles. During
pile installation, depending on local site conditions, it may be
necessary to drive some piles for the final few feet with an impact
hammer. This technique, known as proofing, may be required due to
substrate refusal. As a result of consultation with USFWS under the
ESA, impact pile driving, if required for proofing, will not occur on
more than five days for the duration of any pile driving window during
the implementation of the project, and no more than one pile may be
proofed in a given day. Furthermore, impact driving or proofing would
be limited to fifteen minutes per pile (up to five piles total). Based
on the Navy's experience with pile replacement during previous repair
cycles at the EHW-1 facility, the Navy felt that this measure could be
complied with. During previous repairs at EHW-1, no use of impact
driving has been required to accomplish installation. All piles driven
with an impact hammer would be surrounded by a bubble curtain or other
sound attenuation device over the full water column to minimize in-
water noise. Vibratory pile driving is restricted to the time period
between July 16 and October 31, while impact driving would only be
performed between July 16 and September 30. Non-pile driving, in-water
work can be performed between July 16 and February 15. The Navy will
monitor hydroacoustic levels, as well as the presence and behavior of
marine mammals during pile installation and removal. Under the proposed
action, twenty-eight 30-in steel piles would be installed and 138
piles, steel and concrete, would be removed.
The contractor estimates that steel pile installation and removal
will occur at an average rate of two piles per day. For each pile
installed, the driving time is expected to be no more than one hour for
the vibratory portion of the project. The impact driving portion of the
project, when required, is anticipated to take approximately fifteen
minutes per pile, with a maximum of five piles per construction window
permitted to be impact driven. Impact pile driving will not occur on
more than five days for the duration of any pile driving window and no
more than one pile will be proofed in a given day. Steel piles will be
extracted using a vibratory hammer. Extraction is anticipated to take
approximately thirty minutes per pile. Concrete piles will be removed
using a pneumatic chipping hammer or other similar concrete demolition
tool. It is estimated that concrete pile removal could occur at a rate
of five piles per day maximum, but removal will more likely occur at a
rate of three piles per day. It is expected to take approximately two
hours to remove each concrete pile with a pneumatic chipping hammer.
For steel piles, this results in a maximum of two hours of pile
driving per pile or potentially four hours per day. For concrete piles,
this results in a maximum of two hours of pneumatic chipping per pile,
or potentially six hours per day. Therefore, while 108 days of in-water
work time is proposed (July 16-October 31), only a fraction of the
total work time per day will actually be spent pile driving. An average
work day (two hours post-sunrise to two hours prior to sunset [civil])
ranges from six to twelve hours (for an average of approximately eight
to nine hours), depending on the month. While it is anticipated that
only four hours of pile driving would take place per day for steel
piles, or six hours of pneumatic chipping for concrete piles, the Navy
modeled potential impact as if the entire day could be spent pile
driving to take into account deviations from the estimated times for
pile installation and removal.
Based on the proposed action, the total time from vibratory pile
driving during steel pile installation would be approximately fourteen
days (28 piles at
[[Page 6409]]
an average of two per day). The total time from impact pile driving
during steel pile installation would be five days (five piles at one
per day). The total time from vibratory pile driving during steel pile
removal would be 21 days (42 piles at an average of two per day). The
total time using a pneumatic chipping hammer during concrete pile
removal would be 32 days (96 piles at an average of three per day).
Description of Noise Sources
Underwater sound levels are comprised of multiple sources,
including physical noise, biological noise, and anthropogenic noise.
Physical noise includes waves at the surface, earthquakes, ice, and
atmospheric noise. Biological noise includes sounds produced by marine
mammals, fish, and invertebrates. Anthropogenic noise consists of
vessels (small and large), dredging, aircraft overflights, and
construction noise. Known noise levels and frequency ranges associated
with anthropogenic sources similar to those that would be used for this
project are summarized in Table 1. Details of each of the sources are
described in the following text.
Table 1--Representative Noise Levels of Anthropogenic Sources
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Frequency Underwater noise level (dB
Noise source range (Hz) re 1 [micro]Pa) Reference
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Small vessels....................... 250-1,000 151 dB root mean square Richardson et al. 1995.
(rms) at 1 m (3.3 ft).
Tug docking gravel barge............ 200-1,000 149 dB rms at 100 m (328 ft) Blackwell and Greene 2002.
Vibratory driving of 30-in (0.8 m) 10-1,500 Approximately 168 dB rms at WSDOT 2010a, 2010b.
steel pipe pile. 10 m (33 ft).
Impact driving of 30-in steel pipe 10-1,500 Approximately 193 dB rms at WSDOT 2005, 2008; CALTRANS
pile. 10 m. 2007; Reyff 2005.
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In-water construction activities associated with the project would
include impact pile driving and vibratory pile driving. The sounds
produced by these activities fall into one of two sound types: Pulsed
and non-pulsed. Impact pile driving produces pulsed sounds, while
vibratory pile driving produces non-pulsed (or continuous) sounds. The
distinction between these two general sound types is important because
they have differing potential to cause physical effects, particularly
with regard to hearing (e.g., Ward 1997 in Southall et al. 2007).
Please see Southall et al. (2007) for an in-depth discussion of these
concepts.
Pulsed sounds (e.g., explosions, gunshots, sonic booms, seismic
pile driving pulses, and impact pile driving) are brief, broadband,
atonal transients (ANSI 1986; Harris 1998) and occur either as isolated
events or repeated in some succession. Pulsed sounds are all
characterized by a relatively rapid rise from ambient pressure to a
maximal pressure value followed by a decay period that may include a
period of diminishing, oscillating maximal and minimal pressures.
Pulsed sounds generally have an increased capacity to induce physical
injury as compared with sounds that lack these features.
Non-pulse (intermittent or continuous sounds) can be tonal,
broadband, or both. Some of these non-pulse sounds can be transient
signals of short duration but without the essential properties of
pulses (e.g., rapid rise time). Examples of non-pulse sounds include
vessels, aircraft, machinery operations such as drilling or dredging,
vibratory pile driving, and active sonar systems. The duration of such
sounds, as received at a distance, can be greatly extended in a highly
reverberant environment.
Ambient Noise
By definition, ambient noise is background noise, without a single
source or point (Richardson et al. 1995). Ambient noise varies with
location, season, time of day, and frequency. Ambient noise is
continuous, but with much variability on time scales ranging from less
than one second to one year (Richardson et al. 1995). Ambient
underwater noise at the project area is widely variable over time due
to a number of natural and anthropogenic sources. Sources of naturally
occurring underwater noise include wind, waves, precipitation, and
biological noise (e.g., shrimp, fish, cetaceans). There is also human-
generated noise from ship or boat traffic and other mechanical means
(Urick 1983). Other sources of underwater noise at industrial
waterfronts could come from cranes, generators, and other types of
mechanized equipment on wharves or the adjacent shoreline.
In the vicinity of the project area, the average broadband ambient
underwater noise levels were measured at 114 dB re 1 [mu]Pa between 100
Hz and 20 kHz (Slater 2009). Peak spectral noise from industrial
activity was noted below the 300 Hz frequency, with maximum levels of
110 dB re 1 [mu]Pa noted in the 125 Hz band. In the 300 Hz to 5 kHz
range, average levels ranged between 83-99 dB re 1 [mu]Pa. Wind-driven
wave noise dominated the background noise environment at approximately
5 kHz and above, and ambient noise levels flattened above 10 kHz.
Airborne noise levels at NBKB vary based on location but are
estimated to average around 65 dBA (A-weighted decibels) in the
residential and office park areas, with traffic noise ranging from 60-
80 dBA during daytime hours (Cavanaugh and Tocci 1998). The highest
levels of airborne noise are produced along the waterfront and at the
ordnance handling areas, where estimated noise levels range from 70-90
dBA and may peak at 99 dBA for short durations. These higher noise
levels are produced by a combination of sound sources including heavy
trucks, forklifts, cranes, marine vessels, mechanized tools and
equipment, and other sound-generating industrial or military
activities.
Sound Thresholds
Since 1997, NMFS has used generic sound exposure thresholds to
determine when an activity in the ocean that produces sound might
result in impacts to a marine mammal such that a take by harassment
might occur (NMFS 2005b). To date, no studies have been conducted that
examine impacts to marine mammals from pile driving sounds from which
empirical noise thresholds have been established. Current NMFS practice
regarding exposure of marine mammals to sound is that cetaceans and
pinnipeds exposed to impulsive sounds of 180 and 190 dB rms or above,
respectively, are considered to have been taken by Level A (i.e.,
injurious) harassment. Behavioral harassment (Level B) is
[[Page 6410]]
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 120 dB rms for continuous noise (e.g., vibratory pile driving), but
below injurious thresholds. For airborne noise, pinniped disturbance
from haul-outs has been documented at 100 dB (unweighted) for pinnipeds
in general, and at 90 dB (unweighted) for harbor seals. NMFS uses these
levels as guidelines to estimate when harassment may occur.
Distance to Sound Thresholds
Underwater Sound Propagation Formula--Pile driving would generate
underwater noise that potentially could result in disturbance to marine
mammals transiting the project area. Transmission loss (TL) underwater
is the decrease in acoustic intensity as an acoustic pressure wave
propagates out from a source. TL parameters vary with frequency,
temperature, sea conditions, current, source and receiver depth, water
depth, water chemistry, and bottom composition and topography. The
formula for transmission loss is:
TL = B * log10(R) + C * R
where:
B = logarithmic (predominantly spreading) loss
C = linear (scattering and absorption) loss
R = range from source in meters
For all underwater calculations in this assessment, linear loss (C) was
not used (i.e., C = 0) and transmission loss was calculated using only
logarithmic spreading. Therefore, using practical spreading (B = 15),
the revised formula for transmission loss is TL = 15 log10
(R).
Underwater Noise from Pile Driving--The intensity of pile driving
sounds is greatly influenced by factors such as the type of piles,
hammers, and the physical environment in which the activity takes
place. A large quantity of literature regarding sound pressure levels
recorded from pile driving projects is available for consideration. In
order to determine reasonable sound pressure levels and their
associated affects on marine mammals that are likely to result from
pile driving at NBKB, studies with similar properties to the proposed
action were evaluated. Sound levels associated with vibratory pile
removal are the same as those during vibratory installation (CALTRANS
2007) and have been taken into consideration in the modeling analysis.
There is a lack of empirical data regarding the acoustic output of
chipping hammers. As a result, acoustic information for similar types
of concrete breaking instruments, such as jackhammers and concrete
saws, was also consulted. Overall, studies which met the following
parameters were considered: (1) Pile size and materials: Installation--
steel pipe piles (30-in diameter); Removal--steel pipe piles (12 to 24-
in diameter); Removal--concrete piles (24-in diameter); (2) Hammer
machinery: Installation (steel)--vibratory and impact hammer, Removal
(steel)--vibratory hammer; Removal (concrete)--pneumatic chipping and/
or jackhammer; and (3) Physical environment--shallow depth (less than
100 feet [30 m]).
Table 2--Underwater Sound Pressure Levels From Similar In-Situ Monitored Construction Activities
----------------------------------------------------------------------------------------------------------------
Installation Measured sound
Project and location Pile size and type method Water depth pressure levels
----------------------------------------------------------------------------------------------------------------
Eagle Harbor Maintenance 30-in (0.8 m) steel Impact.......... 10 m (33 ft)..... 193 dB re 1 [mu]Pa
Facility, WA \1\. pipe pile. (rms) at 10 m (33
ft).
Richmond-San Rafael Bridge, 30-in steel pipe pile Impact.......... 4-5 m (13-16 ft). 190 dB re 1 [mu]Pa
CA \2\. (rms) at 10 m.
Friday Harbor Ferry Terminal, 30-in steel pipe pile Impact.......... 10 m............. 196 dB re 1 [mu]Pa
WA \3\. (rms) at 10 m.
Various projects \4\......... 30-in steel CISS \5\ Impact.......... Unknown.......... 192 dB re 1 [mu]Pa
pile. (rms) at 10 m.
Average.......... approximately 193 dB
re 1 [micro]Pa (rms)
at 10 m.
----------------------------------------------------------------------------------------------------------------
\1\ WSDOT 2008.
\2\ CALTRANS 2007.
\3\ WSDOT 2005.
\4\ Reyff 2005.
\5\ Cast-in-steel-shell.
Tables presented here detail representative pile driving sound
pressure levels that have been recorded from similar construction
activities in recent years. Due to the similarity of these actions and
the Navy's proposed action, they represent reasonable sound pressure
levels which could be anticipated and these values were used in the
acoustic modeling and analysis. Table 2 represents sound pressure
levels (SPLs) that may be expected during the installation of the 30-in
steel pipe piles using an impact hammer, should this be required. Table
3 represents SPLs that may be expected during the installation of the
30-in steel piles using a vibratory hammer. Table 4 represents SPLs
that may be expected during the removal of the 12 to 24-in steel pipe
piles and the 24-in concrete pilings.
Table 3--Underwater Sound Pressure Levels From Similar In-Situ Monitored Construction Activities
----------------------------------------------------------------------------------------------------------------
Installation Measured sound
Project and location Pile size and type method Water depth pressure levels
----------------------------------------------------------------------------------------------------------------
Keystone Ferry Terminal, WA 30-in (0.8 m) steel Vibratory....... 5 m (15 ft)...... 166 dB re 1 [micro]Pa
\1\. pipe pile. (rms) at 10 m (33
ft).
Keystone Ferry Terminal, WA 30-in steel pipe pile Vibratory....... 8 m (28 ft)...... 171 dB re 1 [micro]Pa
\1\. (rms) at 10 m.
Vashon Ferry Terminal, WA \2\ 30-in steel pipe pile Vibratory....... 10-12 m (36-40 165 dB re 1 [micro]Pa
ft). (rms) at 10 m.
-----------------------------------------
[[Page 6411]]
Average.......... approximately 168 dB
re 1 [micro]Pa (rms)
at 10 m.
----------------------------------------------------------------------------------------------------------------
\1\ WSDOT 2010a.
\2\ WSDOT 2010b.
Table 4--Underwater Sound Pressure Levels for Pile Removal From Similar In-Situ Monitored Construction
Activities
----------------------------------------------------------------------------------------------------------------
Measured sound
Project and location Pile size and type Removal method Water depth pressure levels
----------------------------------------------------------------------------------------------------------------
Unknown, CA \1\.............. 24-in (0.6 m) steel Vibratory....... approximately 15 165 dB re 1 [micro]Pa
pipe pile. m (49 ft). (rms) at 10 m (33
ft).
United Kingdom \2\........... Unknown size \3\; Jackhammer...... Unknown.......... 161 dB re 1 [micro]Pa
concrete. (rms) at 1 m (3.3
ft).
----------------------------------------------------------------------------------------------------------------
\1\ CALTRANS 2007.
\2\ Nedwell and Howell 2004.
\3\ This is the only literature found for the underwater use of a jackhammer or pneumatic chipping tool. The
size of the pile was not recorded. Since these tools operate to chip portions of concrete from the pile, sound
output is not likely tied to the size of the pile itself as for impact and vibratory pile driving. Therefore,
this data was found to be representative for this project.
Several noise reduction measures can be employed during pile
driving to reduce the high source pressures associated with impact pile
driving. Among these is the use of bubble curtains, cofferdams, pile
caps, or the use of vibratory installation. The efficacy of bubble
curtains is dependent upon a variety of site-specific factors,
including environmental conditions such as water current, sediment
type, and bathymetry; the type and size of the pile; and the type and
energy of the hammer. For the pile replacement project, the Navy
intends to employ noise reduction techniques during impact pile
driving, including the use of sound attenuation systems (e.g., bubble
curtain). See ``Proposed Mitigation'' for more details on the impact
reduction and mitigation measures proposed. The calculations of the
distances to the marine mammal noise thresholds were calculated for
impact installation with and without consideration for mitigation
measures. Thorson and Reyff (2004) determined that a properly designed
bubble curtain could provide a reduction of 5 to 20 dB. Based on
information contained therein, distances calculated with consideration
for mitigation assumed a 10 dB reduction in source levels from the use
of sound attenuation devices, and the Navy used the mitigated distances
for impact pile driving for all analysis in their application. All
calculated distances to and the total area encompassed by the marine
mammal noise thresholds are provided in Tables 5, 6, and 7. Calculated
distance to thresholds using unmitigated impact driving is provided as
reference; no unmitigated impact driving will occur. The USFWS has
requested this as a measure to protect prey of the ESA-endangered
marbled murrelet.
Table 5--Calculated Distance(s) to and Area Encompassed by Underwater Marine Mammal Noise Thresholds During Pile Installation
--------------------------------------------------------------------------------------------------------------------------------------------------------
No mitigation, m With mitigation, m Area, km\2\ (mi
Group Threshold (ft) \1\ (ft) \1\ \2\)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Pinnipeds....................................... Impact driving, injury (190 dB)........ 16 (52) 4 (13) 0.000
Cetaceans....................................... Impact driving, injury (180 dB)........ 74 (243) 16 (52) 0.001 (0.000)
All............................................. Impact driving, disturbance (160 dB)... 1,585 (5,200) 342 (1,122) 0.367 (0.142)
Pinnipeds....................................... Vibratory driving, injury.............. 0 0 0.000
Cetaceans....................................... Vibratory driving, injury.............. 2 (6.6) 2 0.000
All............................................. Vibratory driving, disturbance (120 dB) 15,849 (51,998) \2\ 15,849 \2\ 789.1 (304.7)
--------------------------------------------------------------------------------------------------------------------------------------------------------
All sound levels expressed in dB re 1 [micro]Pa rms. Practical spreading loss (15 log, or 4.5 dB per doubling of distance) used for calculations.
\1\ Sound pressure levels used for calculations were: 193 dB re 1 [mu]Pa @ 10 m (33 ft) for impact and 168 dB re 1 [mu]Pa @ 10 m for vibratory.
\2\ Range calculated is greater than what would be realistic. Hood Canal average width at site is 2.4 km (1.5 mi), and is fetch limited from N to S at
20.3 km (12.6 mi).
Table 6--Calculated Distance(s) to and Area Encompassed by Underwater Marine Mammal Noise Thresholds During Pile
Removal
----------------------------------------------------------------------------------------------------------------
Distance, m (ft) Area, km \2\ (mi
Group Threshold \1\ \2\ \2\)
----------------------------------------------------------------------------------------------------------------
Pinnipeds............................. Vibratory removal, injury (190 0 0.000
dB).
Cetaceans............................. Vibratory removal, injury (180 1 (3.3) 0.000
dB).
All................................... Vibratory removal, disturbance \3\ 10,000 (5,200) \3\ 314.2 (121.3)
(120 dB).
Pinnipeds............................. Chipping hammer, injury (190 0 0.000
dB).
Cetaceans............................. Chipping hammer, injury (180 0 0.000
dB).
[[Page 6412]]
All................................... Chipping hammer, disturbance \3\ 542 (1,778) \3\ 0.929 (0.359)
(120 dB).
----------------------------------------------------------------------------------------------------------------
All sound levels expressed in dB re 1 [mu]Pa rms. Practical spreading loss (15 log, or 4.5 dB per doubling of
distance) used for calculations.
\1\ Specific criteria for pneumatic chipping hammers does not exist. These tools produce continuous sound
similar to vibratory pile driving and therefore use the same criteria for the analysis of effects.
\2\ Sound pressure levels used for calculations were: 165 dB re 1 [mu]Pa @ 10 m (33 ft) for vibratory and 161 dB
re 1 [mu]Pa @ 1 m for chipping hammer.
\3\ Range calculated is greater than what would be realistic. Hood Canal average width at site is 2.4 km (1.5
mi), and is fetch limited from N to S at 20.3 km (12.6 mi).
The calculations presented in Tables 5 and 6 assumed a field free
of obstruction, which is unrealistic, because Hood Canal does not
represent open water conditions (free field). Therefore, sounds would
attenuate as they encounter land masses or bends in the canal. As a
result, some of the distances and areas of impact calculated cannot
actually be attained at the project area. The actual distances to the
behavioral disturbance thresholds for impact and vibratory pile driving
and pneumatic chipping may be shorter than those calculated due to the
irregular contour of the waterfront, the narrowness of the canal, and
the maximum fetch (furthest distance sound waves travel without
obstruction [i.e., line of sight]) at the project area. Table 7 shows
the actual areas encompassed by the marine mammal thresholds during
each stage of the EHW-1 pile replacement project. See Figures 6-1
through 6-4 of the Navy's application for depictions of the areas of
each underwater sound threshold that are predicted to occur at the
project area due to pile driving, during each stage of the project.
Table 7--Actual Area Encompassed by Underwater Marine Mammal Noise
Thresholds
------------------------------------------------------------------------
Area, km \2\ (mi
Group Threshold \1\ \2\)
------------------------------------------------------------------------
Pinnipeds.................... Impact driving, 0.000
injury (190 dB).
Cetaceans.................... Impact driving, 0.001 (0.000)
injury (180 dB).
All.......................... Impact driving, 0.287 (0.111)
disturbance (160
dB).
Pinnipeds.................... Vibratory driving, 0.000
injury (190 dB).
Cetaceans.................... Vibratory driving, 0.000
injury (180 dB).
All.......................... Vibratory driving, 40.3 (15.5)
disturbance (120
dB).
Pinnipeds.................... Vibratory removal, 0.000
injury (190 dB).
Cetaceans.................... Vibratory removal, 0.000
injury (180 dB).
All.......................... Vibratory removal, 35.9 (13.9)
disturbance (120
dB).
Pinnipeds.................... Chipping hammer, 0.000
injury (190 dB).
Cetaceans.................... Chipping hammer, 0.000
injury (180 dB).
All.......................... Chipping hammer, 0.608 (0.235)
disturbance (120
dB).
------------------------------------------------------------------------
Airborne Sound Propagation Formula--Pile driving can generate
airborne noise that could potentially result in disturbance to marine
mammals (specifically, pinnipeds) which are hauled out or at the
water's surface. As a result, the Navy analyzed the potential for
pinnipeds hauled out or swimming at the surface near NBKB to be exposed
to airborne sound pressure levels that could result in Level B
behavioral harassment. The appropriate airborne noise threshold for
behavioral disturbance for all pinnipeds, except harbor seals, is 100
dB re 20 [mu]Pa rms (unweighted). For harbor seals, the threshold is 90
dB re 20 [mu]Pa rms (unweighted). A spherical spreading loss model,
assuming average atmospheric conditions, was used to estimate the
distance to the 100 dB and 90 dB re 20 [mu]Pa rms (unweighted) airborne
thresholds. The formula for calculating spherical spreading loss is:
TL = 20log r
where:
TL = Transmission loss
r = Distance from source to receiver
*Spherical spreading results in a 6 dB decrease in sound pressure
level per doubling of distance.
Airborne Sound from Pile Installation and Removal--As was discussed
for underwater noise from pile driving, the intensity of pile driving
sounds is greatly influenced by factors such as the type of piles,
hammers, and the physical environment in which the activity takes
place. In order to determine reasonable airborne sound pressure levels
and their associated effects on marine mammals that are likely to
result from pile driving at NBKB, studies with similar properties to
the proposed action, as described previously, were evaluated. Table 8
details representative pile driving and removal activities that have
occurred in recent years. Due to the similarity of these actions and
the Navy's proposed action, they represent reasonable sound pressure
levels which could be anticipated.
Table 8--Airborne Sound Pressure Levels From Similar In-Situ Monitored Construction Activities
----------------------------------------------------------------------------------------------------------------
Measured sound
Project and location Pile size and type Method Water depth pressure levels
----------------------------------------------------------------------------------------------------------------
Northstar Island, AK \1\..... 42-in (1.1 m) steel Impact.......... Approximately 12 97 dB re 20 [mu]Pa
pipe pile. m (40 ft). (rms) at 160 m (525
ft).
Friday Harbor Ferry Terminal, 24-in (0.6 m) steel Impact.......... Approximately 10 112 dB re 20 [mu]Pa
WA \2\. pipe pile. m (33 ft). (rms) at 49 m (160
ft).
[[Page 6413]]
Wahkiakum Ferry Terminal \3\. 18-in (0.5 m) steel Vibratory Approximately 3-4 87.5 dB re 20 [mu]Pa
pipe pile. removal. m (10-12 ft). (rms) at 15 m (50
ft).
Keystone Ferry Terminal, WA 30-in (0.8 m) steel Vibratory Approximately 9 m 98 dB re 20 [mu]Pa
\3\. pipe pile. installation. (30 ft). (rms) at 11 m (36
ft).
Unknown \4\.................. Unknown \5\, Concrete Chipping Hammer. Unknown.......... 92 dB re 20 [mu]Pa
(rms) at 10 m (33
ft).
----------------------------------------------------------------------------------------------------------------
\1\ Blackwell et al. 2004.
\2\ WSDOT 2005.
\3\ WSDOT 2010c.
\4\ Cheremisinoff 1996.
\5\ This is the only known data for airborne noise from use of a chipping hammer. The size of the pile was not
recorded. However, since these tools operate to chip portions of concrete from the pile, sound outputs are not
tied to the size of the pile. Therefore, this data was found to be representative for this project.
Based on in-situ recordings from similar construction activities,
the maximum airborne noise levels that would result from impact and
vibratory pile driving are estimated to be 120 dB re 20 [mu]Pa (rms) at
15 m (50 ft) and 98 dB re 20 [mu]Pa (rms) at 11 m (36 ft), respectively
(Blackwell et al. 2004; WSDOT 2005, 2010c). Values for impact driving
from the Northstar Island and Friday Harbor projects were averaged. The
maximum airborne noise level that would result from vibratory removal
and pneumatic chipping are estimated to be 92 dB re 20 [micro]Pa (rms)
at 15 m (50 ft) and 92 dB re 20 [mu]Pa (rms) at 33 ft (10 m),
respectively. The values from projects using vibratory hammers
(Wahkiakum Ferry and Keystone Ferry) were averaged to obtain a
representative value for vibratory removal. This is because the largest
steel piles to be removed at EHW-1 are 24-in diameter; a representative
value was obtained by averaging data from 30-in and 18-in diameter
piles. The distances to the airborne thresholds were calculated with
the airborne transmission loss formula presented previously. All
calculated distances to and the total area encompassed by the airborne
marine mammal noise thresholds are provided in Table 9.
Table 9--Calculated Distances to and Area Encompassed by the Marine Mammal Noise Thresholds In-air From Pile
Driving
----------------------------------------------------------------------------------------------------------------
Airborne behavioral disturbance
----------------------------------------
Species Threshold Area in km \2\ (mi
Distance in m (ft) \2\)
----------------------------------------------------------------------------------------------------------------
Pinnipeds (except harbor seal)........... 100 dB re 20 [mu]Pa rms 159 (522) 0.079 (0.031)
(impact disturbance).
Harbor seal.............................. 90 dB re 20 [mu]Pa rms 501 (1,643) 0.789 (0.305)
(impact disturbance).
Pinnipeds (except harbor seal)........... 100 dB re 20 [mu]Pa rms 9 (30) 0.000
(vibratory disturbance;
installation).
Harbor seal.............................. 90 dB re 20 [mu]Pa rms 29 (95) 0.029 (0.003)
(vibratory disturbance;
installation).
Pinnipeds (except harbor seal)........... 100 dB re 20 [mu]Pa rms 7 (23) 0.000
(vibratory disturbance;
removal).
Harbor seal.............................. 90 dB re 20 [mu]Pa rms 20 (66) 0.001 (0.000)
(vibratory disturbance;
removal).
Pinnipeds (except harbor seal)........... 100 dB re 20 [mu]Pa rms 4 (13) 0.000
(pneumatic chipping).
Harbor seal.............................. 90 dB re 20 [mu]Pa rms 13 (43) 0.001 (0.000)
(pneumatic chipping).
----------------------------------------------------------------------------------------------------------------
All SPLs are reported re 20 [mu]Pa rms (unweighted).
All airborne distances are less than those calculated for
underwater sound thresholds, with the exception of the behavioral
disturbance distances from impact pile driving for harbor seals. This
disturbance zone radius is 501 m, whereas the disturbance zone radius
for underwater noise from impact driving (160-dB) is only 342 m (see
Table 5). Therefore, the monitoring buffer zone for behavioral
disturbance will be expanded to encompass this distance for harbor
seals. For all other activities, protective measures are in place out
to the distances calculated for the underwater thresholds, and the
distances for the airborne thresholds will be covered fully by
mitigation and monitoring measures in place for underwater sound
thresholds. Aside from the aforementioned case, all construction noise
associated with the project would not extend beyond the buffer zone for
underwater sound that would be established to protect seals and sea
lions. No haul-outs or rookeries are located within these radii. See
figures 6-5 through 6-10 of the Navy's application for depictions of
the actual distances for each airborne sound threshold that are
predicted to occur at the project area due to pile driving.
Description of Marine Mammals in the Area of the Specified Activity
There are six marine mammal species, three cetaceans and three
pinnipeds, which may inhabit or transit through the waters nearby NBKB
in the Hood Canal. These include the transient killer whale, harbor
porpoise, Dall's porpoise, Steller sea lion, California sea lion, and
the harbor seal. While the Southern Resident killer whale is resident
to the inland waters of Washington and British Columbia, it has not
been observed in the Hood Canal in decades, and therefore was excluded
from further
[[Page 6414]]
analysis. The Steller sea lion is the only marine mammal that occurs
within the Hood Canal which is listed under the ESA; the Eastern DPS is
listed as threatened. As noted previously, and in Table 10, Steller sea
lions are not present in the project area during the proposed project
timeframe for pile driving (July 16-October 31). Steller sea lions will
not be discussed in detail. All marine mammal species are protected
under the MMPA. This section summarizes the population status and
abundance of these species, followed by detailed life history
information. Table 10 lists the marine mammal species that occur in the
vicinity of NBKB and their estimated densities within the project area
during the proposed timeframe.
Table 10--Marine Mammals Present in the Hood Canal in the Vicinity of NBKB
----------------------------------------------------------------------------------------------------------------
Density in warm
Relative Season of season \3\
Species Stock abundance \1\ occurrence in occurrence (individuals/km
Hood Canal \2\)
----------------------------------------------------------------------------------------------------------------
Steller sea lion
Eastern U.S. DPS............. 50,464 \2\................. Rare to Fall to late N/A
occasional use. spring (Nov-
mid April).
California sea lion
U.S. Stock................... 238,000.................... Common.......... Fall to late \4\0.410
spring (Aug-
May).
Harbor seal
WA inland waters stock....... 14,612 (CV = 0.15)......... Common.......... Year-round; \5\1.31
resident
species in
Hood Canal.
Killer whale
West Coast transient stock... 314........................ Rare to Year-round..... \6\0.038
occasional use.
Dall's porpoise
CA/OR/WA stock............... 48,376 (CV = 0.24)......... Rare to Year-round..... \7\0.043
occasional use.
Harbor porpoise
WA inland waters stock....... 10,682 (CV = 0.38)......... Rare to Year-round..... \7\0.011
occasional use.
----------------------------------------------------------------------------------------------------------------
\1\ NMFS marine mammal stock assessment reports at: http://www.nmfs.noaa.gov/pr/sars/species.htm.
\2\ Average of a given range.
\3\ Warm season refers to the period from May-Oct.
\4\ DoN 2010a.
\5\ Jeffries et al. 2003; Huber et al. 2001.
\6\ London 2006.
\7\ Agness and Tannenbaum 2009a.
California Sea Lion
Species Description--California sea lions are members of the
Otariid family (eared seals). The species, Zalophus californianus,
includes three subspecies: Z. c. wollebaeki (in the Galapagos Islands),
Z. c. japonicus (in Japan, but now thought to be extinct), and Z. c.
californianus (found from southern Mexico to southwestern Canada;
referred to here as the California sea lion) (Carretta et al. 2007).
The California sea lion is sexually dimorphic. Males may reach 1,000 lb
(454 kg) and 8 ft (2.4 m) in length; females grow to 300 lb (136 kg)
and 6 ft (1.8 m) in length. Their color ranges from chocolate brown in
males to a lighter, golden brown in females. At around five years of
age, males develop a bony bump on top of the skull called a sagittal
crest. The crest is visible in the dog-like profile of male sea lion
heads, and hair around the crest gets lighter with age.
Population Abundance--The U.S. stock of California sea lions may
occur in the marine waters nearby NBKB. The stock is estimated at
238,000 and the minimum population size of this stock is 141,842
individuals (Carretta et al. 2007). These numbers are from counts
during the 2001 breeding season of animals that were ashore at the four
major rookeries in southern California and at haul-out sites north to
the Oregon/California border. Sea lions that were at-sea or hauled-out
at other locations were not counted (Carretta et al. 2007). An
estimated 3,000 to 5,000 California sea lions migrate to waters of
Washington and British Columbia during the non-breeding season from
September to May (Jeffries et al. 2000). Peak numbers of up to 1,000
California sea lions occur in Puget Sound (including Hood Canal) during
this time period (Jeffries et al. 2000).
Distribution--The geographic distribution of California sea lions
includes a breeding range from Baja California, Mexico to southern
California. During the summer, California sea lions breed on islands
from the Gulf of California to the Channel Islands and seldom travel
more than about 31 mi (50 km) from the islands (Bonnell et al. 1983).
The primary rookeries are located on the California Channel Islands of
San Miguel, San Nicolas, Santa Barbara, and San Clemente (Le Boeuf and
Bonnell 1980; Bonnell and Dailey 1993). Their distribution shifts to
the northwest in fall and to the southeast during winter and spring,
probably in response to changes in prey availability (Bonnell and Ford
1987).
The non-breeding distribution extends from Baja California north to
Alaska for males, and encompasses the waters of California and Baja
California for females (Reeves et al. 2008; Maniscalco et al. 2004). In
the non-breeding season, an estimated 3,000-5,000 adult and sub-adult
males migrate northward along the coast to central and northern
California, Oregon, Washington, and Vancouver Island from September to
May (Jeffries et al. 2000) and return south the following spring (Mate
1975; Bonnell et al. 1983). Along their migration, they are
occasionally sighted hundreds of miles offshore (Jefferson et al.
1993). Females and juveniles tend to stay closer to the rookeries
(Bonnell et al 1983).
Peak abundance in the Puget Sound is September to May. Although
there are no regular California sea lion haul-outs within the Hood
Canal (Jeffries et al. 2000), they often haul out at several opportune
areas. They are known to utilize man-made structures such as piers,
jetties, offshore buoys, and oil platforms (Riedman 1990). California
sea lions in the Puget Sound sometimes haul out on log booms and Navy
submarines, and are often seen rafted off river mouths (Jeffries et al.
2000; DoN 2001). As many as forty California sea lions have been
observed hauled out at
[[Page 6415]]
NBKB on manmade structures (e.g., submarines, floating security fence,
barges) (Agness and Tannenbaum 2009a; Tannenbaum et al. 2009a; Walters
2009). California sea lions have also been observed swimming in the
Hood Canal in the vicinity of the project area on several occasions and
likely forage in both nearshore marine and inland marine deeper waters
(DoN 2001a).
Behavior and Ecology--California sea lions feed on a wide variety
of prey, including many species of fish and squid (Everitt et al. 1981;
Roffe and Mate 1984; Antonelis et al. 1990; Lowry et al. 1991). In the
Puget Sound region, they feed primarily on fish such as Pacific hake
(Merluccius productus), walleye pollock (Theragra chalcogramma),
Pacific herring (Clupea pallasii), and spiny dogfish (Squalus
acanthias) (Calambokidis and Baird 1994). In some locations where
salmon runs exist, California sea lions also feed on returning adult
and out-migrating juvenile salmonids (London 2006). Sexual maturity
occurs at around four to five years of age for California sea lions
(Heath 2002). California sea lions are gregarious during the breeding
season and social on land during other times.
Acoustics--On land, California sea lions make incessant, raucous
barking sounds; these have most of their energy at less than 2 kHz
(Schusterman et al. 1967). Males vary both the number and rhythm of
their barks depending on the social context; the barks appear to
control the movements and other behavior patterns of nearby
conspecifics (Schusterman 1977). Females produce barks, squeals,
belches, and growls in the frequency range of 0.25-5 kHz, while pups
make bleating sounds at 0.25-6 kHz. California sea lions produce two
types of underwater sounds: Clicks (or short-duration sound pulses) and
barks (Schusterman et al. 1966, 1967; Schusterman and Baillet 1969).
All underwater sounds have most of their energy below 4 kHz
(Schusterman et al. 1967).
The range of maximal hearing sensitivity underwater is between 1-28
kHz (Schusterman et al. 1972). Functional underwater high frequency
hearing limits are between 35-40 kHz, with peak sensitivities from 15-
30 kHz (Schusterman et al. 1972). The California sea lion shows
relatively poor hearing at frequencies below 1 kHz (Kastak and
Schusterman 1998). Peak hearing sensitivities in air are shifted to
lower frequencies; the effective upper hearing limit is approximately
36 kHz (Schusterman 1974). The best range of sound detection is from 2-
16 kHz (Schusterman 1974). Kastak and Schusterman (2002) determined
that hearing sensitivity generally worsens with depth--hearing
thresholds were lower in shallow water, except at the highest frequency
tested (35 kHz), where this trend was reversed. Octave band noise
levels of 65-70 dB above the animal's threshold produced an average
temporary threshold shift (TTS; discussed later in ``Potential Effects
of the Specified Activity on Marine Mammals'') of 4.9 dB in the
California sea lion (Kastak et al. 1999).
Harbor Seal
Species Description--Harbor seals, which are members of the Phocid
family (true seals), inhabit coastal and estuarine waters and shoreline
areas from Baja California, Mexico to western Alaska. For management
purposes, differences in mean pupping date (i.e., birthing) (Temte
1986), movement patterns (Jeffries 1985; Brown 1988), pollutant loads
(Calambokidis et al. 1985) and fishery interactions have led to the
recognition of three separate harbor seal stocks along the west coast
of the continental U.S. (Boveng 1988). The three distinct stocks are:
(1) Inland waters of Washington (including Hood Canal, Puget Sound, and
the Strait of Juan de Fuca out to Cape Flattery), (2) outer coast of
Oregon and Washington, and (3) California (Carretta et al. 2007). The
inland waters of Washington stock is the only stock that is expected to
occur within the project area.
The average weight for adult seals is about 180 lb (82 kg) and
males are slightly larger than females. Male harbor seals weigh up to
245 lb (111 kg) and measure approximately 5 ft (1.5 m) in length. The
basic color of harbor seals' coat is gray and mottled but highly
variable, from dark with light color rings or spots to light with dark
markings (NMFS 2008c).
Population Abundance--Estimated population numbers for the inland
waters of Washington, including the Hood Canal, Puget Sound, and the
Strait of Juan de Fuca out to Cape Flattery, are 14,612 individuals
(Carretta et al. 2007). The minimum population is 12,844 individuals.
The harbor seal is the only species of marine mammal that is
consistently abundant and considered resident in the Hood Canal
(Jeffries et al. 2003). The population of harbor seals in Hood Canal is
a closed population, meaning that they do not have much movement
outside of Hood Canal (London 2006). The abundance of harbor seals in
Hood canal has stabilized, and the population may have reached its
carrying capacity in the mid-1990s with an approximate abundance of
1,000 harbor seals (Jeffries et al. 2003).
Distribution--Harbor seals are coastal species, rarely found more
than 12 mi (20 km) from shore, and frequently occupy bays, estuaries,
and inlets (Baird 2001). Individual seals have been observed several
miles upstream in coastal rivers. Ideal harbor seal habitat includes
haul-out sites, shelter during the breeding periods, and sufficient
food (Bjorge 2002). Haul-out areas can include intertidal and subtidal
rock outcrops, sandbars, sandy beaches, peat banks in salt marshes, and
man-made structures such as log booms, docks, and recreational floats
(Wilson 1978; Prescott 1982; Schneider and Payne 1983; Gilber and
Guldager 1998; Jeffries et al. 2000). Human disturbance can affect
haul-out choice (Harris et al. 2003).
Harbor seals occur throughout Hood Canal and are seen relatively
commonly in the area. They are year-round, non-migratory residents, and
pup (i.e., give birth) in Hood Canal. Surveys in the Hood Canal from
the mid-1970s to 2000 show a fairly stable population between 600-1,200
seals (Jeffries et al. 2003). Harbor seals have been observed swimming
in the waters along NBKB in every month of surveys conducted from 2007-
2010 (Agness and Tannenbaum 2009b; Tannenbaum et al. 2009b). On the
NBKB waterfront, harbor seals have not been observed hauling out in the
intertidal zone, but have been observed hauled-out on man-made
structures such as the floating security fence, buoys, barges, marine
vessels, and logs (Agness and Tannebaum 2009a; Tannenbaum et al.
2009a). The main haul-out locations for harbor seals in Hood Canal are
located on river delta and tidal exposed areas at Quilcene,
Dosewallips, Duckabush, Hamma Hamma, and Skokomish River mouths (see
Figure 4-1 of the Navy's application), with the closest haul-out area
to the project area being ten miles (16 km) southwest of NBKB at
Dosewallips River mouth (London 2006).
Behavior and Ecology--Harbor seals are typically seen in small
groups resting on tidal reefs, boulders, mudflats, man-made structures,
and sandbars. Harbor seals are opportunistic feeders that adjust their
patterns to take advantage of locally and seasonally abundant prey
(Payne and Selzer 1989; Baird 2001; Bj[oslash]rge 2002). The harbor
seal diet consists of fish and invertebrates (Bigg 1981; Roffe and Mate
1984; Orr et al. 2004). Although harbor seals in the Pacific Northwest
are common in inshore and estuarine waters, they primarily feed at sea
(Orr
[[Page 6416]]
et al. 2004) during high tide. Researchers have found that they
complete both shallow and deep dives during hunting depending on the
availability of prey (Tollit et al. 1997). Their diet in Puget Sound
consists of many of the prey resources that are present in the
nearshore and deeper waters of NBKB, including hake, herring and adult
and out-migrating juvenile salmonids. Harbor seals in Hood Canal are
known to feed on returning adult salmon, including ESA-threatened
summer-run chum (Oncorhynchus keta). Over a five-year study of harbor
seal predation in the Hood Canal, the average percent escapement of
summer-run chum consumed was eight percent (London 2006).
Harbor seals mate at sea and females give birth during the spring
and summer, although the pupping season varies by latitude. In coastal
and inland regions of Washington, pups are born from April through
January. Pups are generally born earlier in the coastal areas and later
in the Puget Sound/Hood Canal region (Calambokidis and Jeffries 1991;
Jeffries et al. 2000). Suckling harbor seal pups spend as much as forty
percent of their time in the water (Bowen et al. 1999).
Acoustics--In air, harbor seal males produce a variety of low-
frequency (less than 4 kHz) vocalizations, including snorts, grunts,
and growls. Male harbor seals produce communication sounds in the
frequency range of 100-1,000 Hz (Richardson et al. 1995). Pups make
individually unique calls for mother recognition that contain multiple
harmonics with main energy below 0.35 kHz (Bigg 1981; Thomson and
Richardson 1995). Harbor seals hear nearly as well in air as underwater
and had lower thresholds than California sea lions (Kastak and
Schusterman 1998). Kastak and Schusterman (1998) reported airborne low
frequency (100 Hz) sound detection thresholds at 65.4 dB re 20 [mu]Pa
for harbor seals. In air, they hear frequencies from 0.25-30 kHz and
are most sensitive from 6-16 kHz (Richardson 1995; Terhune and Turnbull
1995; Wolski et al. 2003).
Adult males also produce underwater sounds during the breeding
season that typically range from 0.25-4 kHz (duration range: 0.1 s to
multiple seconds; Hanggi and Schusterman 1994). Hanggi and Schusteman
(1994) found that there is individual variation in the dominant
frequency range of sounds between different males, and Van Parijs et
al. (2003) reported oceanic, regional, population, and site-specific
variation that could be vocal dialects. In water, they hear frequencies
from 1-75 kHz (Southall et al. 2007) and can detect sound levels as
weak as 60-85 dB re 1 [mu]Pa within that band. They are most sensitive
at frequencies below 50 kHz; above 60 kHz sensitivity rapidly
decreases.
Killer Whale
Species Description--Killer whales are members of the Delphinid
family and are the most widely distributed cetacean species in the
world. Killer whales have a distinctive color pattern, with black
dorsal and white ventral portions. They also have a conspicuous white
patch above and behind the eye and a highly variable gray or white
saddle area behind the dorsal fin. The species shows considerable
sexual dimorphism. Adult males develop larger pectoral flippers, dorsal
fins, tail flukes, and girths than females. Male adult killer whales
can reach up to 32 ft (9.8 m) in length and weigh nearly 22,000 lb
(10,000 kg); females reach 28 ft (8.5 m) in length and weigh up to
16,500 lb (7,500 kg).
Based on appearance, feeding habits, vocalizations, social
structure, and distribution and movement patterns there are three types
of populations of killer whales (Wiles 2004; NMFS 2005). The three
distinct forms or types of killer whales recognized in the North
Pacific Ocean are: (1) Resident, (2) Transient, and (3) Offshore. The
resident and transient populations have been divided further into
different subpopulations based mainly on genetic analyses and
distribution; not enough is known about the offshore whales to divide
them into subpopulations (Wiles 2004). Only transient killer whales are
known from the project area.
Transient killer whales occur throughout the eastern North Pacific,
and have primarily been studied in coastal waters. Their geographical
range overlaps that of the resident and offshore killer whales. The
dorsal fin of transient whales tends to be more erect (straighter at
the tip) than those of resident and offshore whales (Ford and Ellis
1999; Ford et al. 2000). Saddle patch pigmentation of transient killer
whales is restricted to two patterns, and never has the large areas of
black pigmentation intruding into the white of the saddle patch that is
seen in resident and offshore types. Transient-type whales are often
found in long-term stable social units that tend to be smaller than
resident social groups (e.g., fewer than ten whales); these social
units do not seem as permanent as matrilines are in resident type
whales. Transient killer whales feed nearly exclusively on marine
mammals (Ford and Ellis 1999), whereas resident whales primarily eat
fish. Offshore whales are presumed to feed primarily on fish, and have
been documented feeding on sharks.
Within the transient type, association data (Ford et al. 1994; Ford
and Ellis 1999; Matkin et al. 1999), acoustic data (Saulitis 1993; Ford
and Ellis 1999) and genetic data (Hoelzel et al. 1998, 2002; Barrett-
Lennard 2000) confirms that three communities of transient whales exist
and represent three discrete populations: (1) Gulf of Alaska, Aleutian
Islands, and Bering Sea transients, (2) AT1 transients (Prince William
Sound, AK; listed as depleted under the MMPA), and (3) West Coast
transients. Among the genetically distinct assemblages of transient
killer whales in the northeastern Pacific, only the West Coast
transient stock, which occurs from southern California to southeastern
Alaska, may occur in the project area.
Population Abundance--The West Coast transient stock is a trans-
boundary stock, with minimum counts for the population of transient
killer whales coming from various photographic datasets. Combining
these counts of cataloged transient whales gives a minimum number of
314 individuals for the West Coast transient stock (Allen and Angliss
2010). However, the number in Washington waters at any one time is
probably fewer than twenty individuals (Wiles 2004).
Distribution--The geographical range of transient killer whales
includes the northeast Pacific, with preference for coastal waters of
southern Alaska and British Columbia (Krahn et al. 2002). Transient
killer whales in the eastern North Pacific spend most of their time
along the outer coast, but visit Hood Canal and the Puget Sound in
search of harbor seals, sea lions, and other prey. Transient occurrence
in inland waters appears to peak during August and September (Morton
1990; Baird and Dill 1995; Ford and Ellis 1999) which is the peak time
for harbor seal pupping, weaning, and post-weaning (Baird and Dill
1995). In 2003 and 2005, small groups of transient killer whales
(eleven and six individuals, respectively) visited Hood Canal to feed
on harbor seals and remained in the area for significant periods of
time (59 and 172 days, respectively) between the months of January and
July.
Behavior and Ecology--Transient killer whales show greater
variability in habitat use, with some groups spending most of their
time foraging in shallow waters close to shore while others hunt almost
entirely in open water (Felleman et al. 1991; Baird and Dill 1995;
Matkin and Saulitis 1997). Transient killer whales feed on marine
mammals and some seabirds, but apparently no fish
[[Page 6417]]
(Morton 1990; Baird and Dill 1996; Ford et al. 1998; Ford and Ellis
1999; Ford et al. 2005). While present in Hood Canal in 2003 and 2005,
transient killer whales preyed on harbor seals in the subtidal zone of
the nearshore marine and inland marine deeper water habitats (London
2006). Other observations of foraging transient killer whales indicate
they prefer to forage on pinnipeds in shallow, protected waters
(Heimlich-Boran 1988; Saulitis et al. 2000). Transient killer whales
travel in small, matrilineal groups, but they typically contain fewer
than ten animals and their social organization generally is more
flexible than that of resident killer whales (Morton 1990, Ford and
Ellis 1999). These differences in social organization probably relate
to differences in foraging (Baird and Whitehead 2000). There is no
information on the reproductive behavior of killer whales in this area.
Acoustics--Killer whales produce a wide variety of clicks and
whistles, but most of their sounds are pulsed, with frequencies ranging
from 0.5-25 kHz (dominant frequency range: 1-6 kHz) (Thomson and
Richardson 1995; Richardson et al. 1995). Source levels of echolocation
signals range between 195-224 dB re 1 [mu]Pa-m peak-to-peak (p-p),
dominant frequencies range from 20-60 kHz, with durations of about 0.1
s (Au et al. 2004). Source levels associated with social sounds have
been calculated to range between 131-168 dB re 1 [mu]Pa-m and vary with
vocalization type (Veirs 2004).
Both behavioral and auditory brainstem response technique indicate
killer whales can hear in a frequency range of 1-100 kHz and are most
sensitive at 20 kHz. This is one of the lowest maximum-sensitivity
frequencies known among toothed whales (Szymanski et al. 1999).
Dall's Porpoise
Species Description--Dall's porpoises are members of the Phocoenid
(porpoise) family and are common in the North Pacific Ocean. They can
reach a maximum length of just under 8 ft (2.4 m) and weigh up to 480
lb (218 kg). Males are slightly larger and thicker than females, which
reach lengths of just under 7 ft (2.1 m) long. The body of Dall's
porpoises is a very dark gray or black in coloration with variable
contrasting white thoracic panels and white `frosting' on the dorsal
fin and tail that distinguish them from other cetacean species. These
markings and colorations vary with geographic region and life stage,
with adults having more distinct patterns.
Based on NMFS stock assessment reports, Dall's porpoises within the
Pacific U.S. Exclusive Economic Zone are divided into two discrete,
noncontiguous areas: (1) Waters off California, Oregon, and Washington,
and (2) Alaskan waters (Carretta et al. 2008). Only individuals from
the CA/OR/WA stock may occur within the project area.
Population Abundance--The NMFS population estimate, recently
updated in 2008 for the CA/OR/WA stock, is 48,376 (CV = 0.24) which is
based on vessel line transect surveys by Barlow and Forney (2007) and
Forney (2007) (Carretta et al. 2008). The minimum population is
considered to be 39,709. Additional numbers of Dall's porpoises occur
in the inland waters of Washington, but the most recent estimate was
obtained in 1996 (900 animals; CV = 0.40; Calambokidis et al. 1997) and
is not included in the overall estimate of abundance for this stock due
to the need for more up-to-date information.
Distribution--The Dall's porpoise is found from northern Baja
California, Mexico, north to the northern Bering Sea and south to
southern Japan (Jefferson et al. 1993). The species is only common
between 32-62[deg]N in the eastern North Pacific (Morejohn 1979; Houck
and Jefferson 1999). North-south movements in California, Oregon, and
Washington have been suggested. Dall's porpoises shift their
distribution southward during cooler-water periods (Forney and Barlow
1998). Norris and Prescott (1961) reported finding Dall's porpoises in
southern California waters only in the winter, generally when the water
temperature was less than 15 [deg]C (59 [deg]F). Seasonal movements
have also been noted off Oregon and Washington, where higher densities
of Dall's porpoises were sighted offshore in winter and spring and
inshore in summer and fall (Green et al. 1992).
In Washington, they are most abundant in offshore waters. They are
year-round residents in Washington (Green et al. 1992), but their
distribution is highly variable between years, likely due to changes in
oceanographic conditions (Forney and Barlow 1998). Dall's porpoises are
observed throughout the year in the Puget Sound north of Seattle
(Osborne et al. 1998) and are seen occasionally in southern Puget
Sound. Dall's porpoises may also occasionally occur in Hood Canal
(Jeffries 2006, personal communication). Nearshore habitats used by
Dall's porpoises could include the marine habitats found in the inland
marine waters of the Hood Canal. A Dall's porpoise was observed in the
deeper water at NBKB in summer 2008 (Tannenbaum et al. 2009a).
Behavior and Ecology--Dall's porpoises can be opportunistic feeders
but primarily consume schooling forage fish. They are known to eat
squid, crustaceans, and fishes such as blackbelly eelpout (Lycodopsis
pacifica), herring, pollock, hake, and Pacific sandlance (Ammodytes
hexapterus) (Walker et al. 1998). Groups of Dall's porpoises generally
include fewer than ten individuals and are fluid, probably aggregating
for feeding (Jefferson 1990, 1991; Houck and Jefferson 1999). Dall's
porpoises become sexually mature at three and a half to eight years of
age (Houck and Jefferson 1999) and give birth to a single calf after
ten to twelve months. Breeding and calving typically occurs in the
spring and summer (Angell and Balcomb 1982). In the North Pacific,
there is a strong summer calving peak from early June through August
(Ferrero and Walker 1999), and a smaller peak in March (Jefferson
1989). Resident Dall's porpoises breed in Puget Sound from August to
September.
Acoustics--Only short duration pulsed sounds have been recorded for
Dall's porpoises (Houck and Jefferson 1999); this species apparently
does not whistle often (Richardson et al. 1995). Dall's porpoises
produce short duration (50-1,500 [mu]s), high-frequency, narrow band
clicks, with peak energies between 120-160 kHz (Jefferson 1988). There
is no published data on the hearing abilities of this species.
Harbor Porpoise
Species Description--Harbor porpoises belong to the Phocoenid
(porpoise) family and are found extensively along the Pacific U.S.
coast. Harbor porpoises are small, with males reaching average lengths
of approximately 5 ft (1.5 m); Females are slightly larger with an
average length of 5.5 ft (1.7 m). The average adult harbor porpoise
weighs between 135-170 lb (61-77 kg). Harbor porpoises have a dark grey
coloration on their backs, with their belly and throats white. They
have a dark grey chin patch and intermediate shades of grey along their
sides.
Recent preliminary genetic analyses of samples ranging from
Monterey, CA to Vancouver Island, BC indicate that there is small-scale
subdivision within the U.S. portion of this range (Chivers et al.
2002). Although geographic structure exists along an almost continuous
distribution of harbor porpoises from California to Alaska, stock
boundaries are difficult to draw because any rigid line is generally
arbitrary from a biological perspective.
[[Page 6418]]
Nevertheless, based on genetic data and density discontinuities
identified from aerial surveys, NMFS identifies eight stocks in the
Northeast Pacific Ocean. Pacific coast harbor porpoise stocks include:
(1) Monterey Bay, (2) San Francisco-Russian River, (3) northern
California/southern Oregon, (4) Oregon/Washington coastal, (5) inland
Washington, (6) Southeast Alaska, (7) Gulf of Alaska, and (8) Bering
Sea. Only individuals from the Washington Inland Waters stock may occur
in the project area.
Population Abundance--Aerial surveys of the inland waters of
Washington and southern British Columbia were conducted during August
of 2002 and 2003 (J. Laake, unpubl. data). These aerial surveys
included the Strait of Juan de Fuca, San Juan Islands, Gulf Islands,
and Strait of Georgia, which includes waters inhabited by the
Washington Inland Waters stock of harbor porpoises as well as harbor
porpoises from British Columbia. An average of the 2002 and 2003
estimates of abundance in U.S. waters resulted in an uncorrected
abundance of 3,123 (CV = 0.10) harbor porpoises in Washington inland
waters (J. Laake, unpubl. data). When corrected for availability and
perception bias, the estimated abundance for the Washington Inland
Waters stock of harbor porpoise is 10,682 (CV = 0.38) animals (Carretta
et al. 2008). The minimum population estimate is 7,841.
Distribution--Harbor porpoises are generally found in cool
temperate to subarctic waters over the continental shelf in both the
North Atlantic and North Pacific (Read 1999). This species is seldom
found in waters warmer than 17 [deg]C (63 [deg]F; Read 1999) or south
of Point Conception (Hubbs 1960; Barlow and Hanan 1995). Harbor
porpoises can be found year-round primarily in the shallow coastal
waters of harbors, bays, and river mouths (Green et al. 1992). Along
the Pacific coast, harbor porpoises occur from Monterey Bay, California
to the Aleutian Islands and west to Japan (Reeves et al. 2002). Harbor
porpoises are known to occur in Puget Sound year round (Osmek et al.
1996, 1998; Carretta et al. 2007), and may occasionally occur in Hood
Canal (Jeffries 2006, pers. comm.). Harbor porpoise observations in
northern Hood Canal have increased in recent years (Calambokidis 2010,
pers. comm.). A harbor porpoise was seen in deeper water at NBKB during
2010 field observations (SAIC 2010, staff obs.).
Behavior and Ecology--Harbor porpoises are non-social animals
usually seen in small groups of two to five animals. Little is known
about their social behavior. Harbor porpoises can be opportunistic
foragers but primarily consume schooling forage fish (Osmek et al.
1996; Bowen and Siniff 1999; Reeves et al. 2002). Along the coast of
Washington, harbor porpoises primarily feed on herring, market squid
(Loligo opalescens) and eulachon (Thaleichthys pacificus) (Gearin et
al. 1994). Females reach sexual maturity at three to four years of age
and may give birth every year for several years in a row. Calves are
born in late spring (Read 1990; Read and Hohn 1995). Dall's and harbor
porpoises appear to hybridize relatively frequently in the Puget Sound
area (Willis et al. 2004).
Acoustics--Harbor porpoise vocalizations include clicks and pulses
(Ketten 1998), as well as whistle-like signals (Verboom and Kastelein
1995). The dominant frequency range is 110-150 kHz, with source levels
of 135-177 dB re 1 [mu]Pa-m (Ketten 1998). Echolocation signals include
one or two low-frequency components in the 1.4-2.5 kHz range (Verboom
and Kastelein 1995).
A behavioral audiogram of a harbor porpoise indicated the range of
best sensitivity is 8-32 kHz at levels between 45-50 dB re 1 [mu]Pa-m
(Andersen 1970); however, auditory-evoked potential studies showed a
much higher frequency of approximately 125-130 kHz (Bibikov 1992). The
auditory-evoked potential method suggests that the harbor porpoise
actually has two frequency ranges of best sensitivity. More recent
psycho-acoustic studies found the range of best hearing to be 16-140
kHz, with a reduced sensitivity around 64 kHz (Kastelein et al. 2002).
Maximum sensitivity occurs between 100-140 kHz (Kastelein et al. 2002).
Potential Effects of the Specified Activity on Marine Mammals
NMFS has determined that pile driving, as outlined in the project
description, has the potential to result in behavioral harassment of
California sea lions, harbor seals, harbor porpoises, Dall's porpoises,
and killer whales that may be swimming, foraging, or resting in the
project vicinity while pile driving is being conducted. Pile driving
could potentially harass those pinnipeds that are in the water close to
the project site, whether their heads are above or below the surface.
Marine Mammal Hearing
The primary effect on marine mammals anticipated from the specified
activities will result from exposure of animals to underwater sound.
Exposure to sound can affect marine mammal hearing. When considering
the influence of various kinds of sound on the marine environment, it
is necessary to understand that different kinds of marine life are
sensitive to different frequencies of sound. Based on available
behavioral data, audiograms derived using auditory evoked potential
techniques, anatomical modeling, and other data, Southall et al. (2007)
designate functional hearing groups for marine mammals and estimate the
lower and upper frequencies of functional hearing of the groups. The
functional groups and the associated frequencies are indicated below
(though animals are less sensitive to sounds at the outer edge of their
functional range and most sensitive to sounds of frequencies within a
smaller range somewhere in the middle of their functional hearing
range):
Low frequency cetaceans (thirteen species of mysticetes):
Functional hearing is estimated to occur between approximately 7 Hz and
22 kHz;
Mid-frequency cetaceans (32 species of dolphins, six
species of larger toothed whales, and nineteen species of beaked and
bottlenose whales): Functional hearing is estimated to occur between
approximately 150 Hz and 160 kHz;
High frequency cetaceans (six species of true porpoises,
four species of river dolphins, two members of the genus Kogia, and
four dolphin species of the genus Cephalorhynchus): Functional hearing
is estimated to occur between approximately 200 Hz and 180 kHz; and
Pinnipeds in water: Functional hearing is estimated to
occur between approximately 75 Hz and 75 kHz, with the greatest
sensitivity between approximately 700 Hz and 20 kHz.
As mentioned previously in this document, two pinnipeds and three
cetacean species are likely to occur in the proposed project area. Of
the three cetacean species likely to occur in the project area, two are
classified as high frequency cetaceans (Dall's and harbor porpoises)
and one is classified as a mid-frequency cetacean (killer whales)
(Southall et al. 2007).
Underwater Noise Effects
Potential Effects of Pile Driving Noise--The effects of sounds from
pile driving might result in one or more of the following: Temporary or
permanent hearing impairment, non-auditory physical or physiological
effects, behavioral disturbance, and masking (Richardson et al. 1995;
Gordon et al. 2004; Nowacek et al. 2007; Southall et al. 2007). The
effects of pile driving on marine mammals are dependent on several
factors, including the size, type,
[[Page 6419]]
and depth of the animal; the depth, intensity, and duration of the pile
driving sound; the depth of the water column; the substrate of the
habitat; the standoff distance between the pile and the animal; and the
sound propagation properties of the environment. Impacts to marine
mammals from pile driving activities are expected to result primarily
from acoustic pathways. As such, the degree of effect is intrinsically
related to the received level and duration of the sound exposure, which
are in turn influenced by the distance between the animal and the
source. The further away from the source, the less intense the exposure
should be. The substrate and depth of the habitat affect the sound
propagation properties of the environment. Shallow environments are
typically more structurally complex, which leads to rapid sound
attenuation. In addition, substrates that are soft (e.g., sand) will
absorb or attenuate the sound more readily than hard substrates (e.g.,
rock) which may reflect the acoustic wave. Soft porous substrates would
also likely require less time to drive the pile, and possibly less
forceful equipment, which would ultimately decrease the intensity of
the acoustic source.
In the absence of mitigation, impacts to marine species would be
expected to result from physiological and behavioral responses to both
the type and strength of the acoustic signature (Viada et al. 2008).
The type and severity of behavioral impacts are more difficult to
define due to limited studies addressing the behavioral effects of
impulsive sounds on marine mammals. Potential effects from impulsive
sound sources can range in severity, ranging from effects such as
behavioral disturbance, tactile perception, physical discomfort, slight
injury of the internal organs and the auditory system, to mortality
(Yelverton et al. 1973; O'Keefe and Young 1984; DoN 2001b).
Hearing Impairment and Other Physical Effects--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 not recoverable, or
temporary (TTS), in which case the animal's hearing threshold will
recover over time (Southall et al. 2007). Marine mammals depend on
acoustic cues for vital biological functions, (e.g., orientation,
communication, finding prey, avoiding predators); thus, TTS may result
in reduced fitness in survival and reproduction, either permanently or
temporarily. However, this depends on both the frequency and duration
of TTS, as well as the biological context in which it occurs. TTS of
limited duration, occurring in a frequency range that does not coincide
with that used for recognition of important acoustic cues, would have
little to no effect on an animal's fitness. Repeated noise exposure
that leads to TTS could cause PTS. PTS, in the unlikely event that it
occurred, would constitute injury, but TTS is not considered injury
(Southall et al. 2007). It is unlikely that the project would result in
any cases of temporary or especially permanent hearing impairment or
any significant non-auditory physical or physiological effects for
reasons discussed later in this document. Some behavioral disturbance
is expected, but it is likely that this would be localized and short-
term because of the short project duration.
Several aspects of the planned monitoring and mitigation measures
for this project (see the ``Proposed Mitigation'' and ``Proposed
Monitoring and Reporting'' sections later in this document) are
designed to detect marine mammals occurring near the pile driving to
avoid exposing them to sound pulses that might, in theory, cause
hearing impairment. In addition, many cetaceans are likely to show some
avoidance of the area where received levels of pile driving sound are
high enough that hearing impairment could potentially occur. In those
cases, the avoidance responses of the animals themselves will reduce or
(most likely) avoid any possibility of hearing impairment. Non-auditory
physical effects may also occur in marine mammals exposed to strong
underwater pulsed sound. It is especially unlikely that any effects of
these types would occur during the present project given the brief
duration of exposure for any given individual and the planned
monitoring and mitigation measures. The following subsections discuss
in somewhat more detail the possibilities of TTS, PTS, and non-auditory
physical effects.
Temporary Threshold Shift--TTS is the mildest form of hearing
impairment that can occur during exposure to a strong sound (Kryter
1985). While experiencing TTS, the hearing threshold rises, and a sound
must be stronger in order to be heard. In terrestrial mammals, TTS can
last from minutes or hours to days (in cases of strong TTS). For sound
exposures at or somewhat above the TTS threshold, hearing sensitivity
in both terrestrial and marine mammals recovers rapidly after exposure
to the sound ends. Few data on sound levels and durations necessary to
elicit mild TTS have been obtained for marine mammals, and none of the
published data concern TTS elicited by exposure to multiple pulses of
sound. Available data on TTS in marine mammals are summarized in
Southall et al. (2007).
Given the available data, the received level of a single pulse
(with no frequency weighting) might need to be approximately 186 dB re
1 [mu]Pa\2\-s (i.e., 186 dB sound exposure level [SEL] or approximately
221-226 dB pk-pk) in order to produce brief, mild TTS. Exposure to
several strong pulses that each have received levels near 190 dB re 1
[mu]Pa rms (175-180 dB SEL) might result in cumulative exposure of
approximately 186 dB SEL and thus slight TTS in a small odontocete,
assuming the TTS threshold is (to a first approximation) a function of
the total received pulse energy. Levels greater than or equal to 190 dB
re 1 [mu]Pa rms are expected to be restricted to radii no more than 5 m
(16 ft) from the pile driving. For an odontocete closer to the surface,
the maximum radius with greater than or equal to 190 dB re 1 [mu]Pa rms
would be smaller.
The above TTS information for odontocetes is derived from studies
on the bottlenose dolphin (Tursiops truncatus) and beluga whale
(Delphinapterus leucas). There is no published TTS information for
other species of cetaceans. However, preliminary evidence from a harbor
porpoise exposed to pulsed sound suggests that its TTS threshold may
have been lower (Lucke et al. 2009). To avoid the potential for injury,
NMFS has determined that cetaceans should not be exposed to pulsed
underwater noise at received levels exceeding 180 dB re 1 [mu]Pa rms.
As summarized above, data that are now available imply that TTS is
unlikely to occur unless odontocetes are exposed to pile driving pulses
stronger than 180 dB re 1 [mu]Pa rms.
Permanent Threshold Shift--When PTS occurs, there is physical
damage to the sound receptors in the ear. In severe cases, there can be
total or partial deafness, while in other cases the animal has an
impaired ability to hear sounds in specific frequency ranges (Kryter
1985). There is no specific evidence that exposure to pulses of sound
can cause PTS in any marine mammal. However, given the possibility that
mammals close to pile driving activity might incur TTS, there has been
further speculation about the possibility that some individuals
occurring very close to pile driving might incur PTS. Single or
occasional occurrences of mild TTS are not indicative of permanent
auditory damage, but repeated or (in
[[Page 6420]]
some cases) single exposures to a level well above that causing TTS
onset might elicit PTS.
Relationships between TTS and PTS thresholds have not been studied
in marine mammals but are assumed to be similar to those in humans and
other terrestrial mammals. PTS might occur at a received sound level at
least several decibels above that inducing mild TTS if the animal were
exposed to strong sound pulses with rapid rise time. Based on data from
terrestrial mammals, a precautionary assumption is that the PTS
threshold for impulse sounds (such as pile driving pulses as received
close to the source) is at least 6 dB higher than the TTS threshold on
a peak-pressure basis and probably greater than 6 dB (Southall et al.
2007). On an SEL basis, Southall et al. (2007) estimated that received
levels would need to exceed the TTS threshold by at least 15 dB for
there to be risk of PTS. Thus, for cetaceans, Southall et al. (2007)
estimate that the PTS threshold might be an M-weighted SEL (for the
sequence of received pulses) of approximately 198 dB re 1 [mu]Pa\2\-s
(15 dB higher than the TTS threshold for an impulse). Given the higher
level of sound necessary to cause PTS as compared with TTS, it is
considerably less likely that PTS could occur.
Non-auditory Physiological Effects--Non-auditory physiological
effects or injuries that theoretically might occur in marine mammals
exposed to strong underwater sound include stress, neurological
effects, bubble formation, resonance effects, and other types of organ
or tissue damage (Cox et al. 2006; Southall et al. 2007). Studies
examining such effects are limited. In general, little is known about
the potential for pile driving to cause auditory impairment or other
physical effects in marine mammals. Available data suggest that such
effects, if they occur at all, would presumably be limited to short
distances from the sound source and to activities that extend over a
prolonged period. The available data do not allow identification of a
specific exposure level above which non-auditory effects can be
expected (Southall et al. 2007) or any meaningful quantitative
predictions of the numbers (if any) of marine mammals that might be
affected in those ways. Marine mammals that show behavioral avoidance
of pile driving, including some odontocetes and some pinnipeds, are
especially unlikely to incur auditory impairment or non-auditory
physical effects.
Measured source levels from impact pile driving can be as high as
214 dB re 1 [mu]Pa at 1 m (3.3 ft). Although no marine mammals have
been shown to experience TTS or PTS as a result of being exposed to
pile driving activities, captive bottlenose dolphins and beluga whales
exhibited changes in behavior when exposed to strong pulsed sounds
(Finneran et al. 2000, 2002, 2005). The animals tolerated high received
levels of sound before exhibiting aversive behaviors. Experiments on a
beluga whale showed that exposure to a single watergun impulse at a
received level of 207 kPa (30 psi) 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 four minutes of the exposure (Finneran et al.
2002). 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 a prolonged
period of time. Based on the best scientific information available,
these SPLs are far below the thresholds that could cause TTS or the
onset of PTS.
Disturbance Reactions
Disturbance includes a variety of effects, including subtle changes
in behavior, more conspicuous changes in activities, and displacement.
Reactions to sound, if any, depend on species, state of maturity,
experience, current activity, reproductive state, time of day, and many
other factors (Richardson et al. 1995; Wartzok et al. 2004; Southall et
al. 2007; Weilgart 2007). Behavioral responses to sound are highly
variable and context specific. For each potential behavioral change,
the magnitude of the change ultimately determines the severity of the
response. A number of factors may influence an animal's response to
noise, including its previous experience, its auditory sensitivity, its
biological and social status (including age and sex), and its
behavioral state and activity at the time of exposure.
Habituation can occur when an animal's response to a stimulus wanes
with repeated exposure, usually in the absence of unpleasant associated
events (Wartzok et al. 2003/04). Animals are most likely to habituate
to sounds that are predictable and unvarying. The opposite process is
sensitization, when an unpleasant experience leads to subsequent
responses, often in the form of avoidance, at a lower level of
exposure. Behavioral state may affect the type of response as well. For
example, animals that are resting may show greater behavioral change in
response to disturbing noise levels than animals that are highly
motivated to remain in an area for feeding (Richardson et al. 1995; NRC
2003; Wartzok et al. 2003/04).
Controlled experiments with captive marine mammals showed
pronounced behavioral reactions, including avoidance of loud sound
sources (Ridgway et al. 1997; Finneran et al. 2003). Observed responses
of wild marine mammals to loud pulsed sound sources (typically seismic
guns or acoustic harassment devices, but also including pile driving)
have been varied but often consist of avoidance behavior or other
behavioral changes suggesting discomfort (Morton and Symonds 2002;
CALTRANS 2001, 2006; see also Gordon et al. 2004; Wartzok et al. 2003/
04; Nowacek et al. 2007). Responses to continuous noise, such as
vibratory pile installation, have not been documented as well as
responses to pulsed sounds.
With both types of pile driving, it is likely that the onset of
pile driving could result in temporary, short term changes in an
animal's typical behavior and/or avoidance of the affected area. These
behavioral changes may include (Richardson et al. 1995): 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 haul-outs or rookeries). Pinnipeds
may increase their haul-out time, possibly to avoid in-water
disturbance (CALTRANS 2001, 2006). Since pile driving will likely only
occur for a few hours a day, over a short period of time, it is
unlikely to result in permanent displacement. Any potential impacts
from pile driving activities could be experienced by individual marine
mammals, but would not be likely to cause population level impacts, or
affect the long-term fitness of the species.
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
[[Page 6421]]
biologically significant if the change affects growth, survival, or
reproduction. Significant behavioral modifications that could
potentially lead to effects on growth, survival, or reproduction
include:
Drastic changes 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
Cessation of feeding or social interaction.
The onset of behavioral disturbance from anthropogenic noise
depends on both external factors (characteristics of noise sources and
their paths) and the specific characteristics of the receiving animals
(hearing, motivation, experience, demography) and is difficult to
predict (Southall et al. 2007).
Auditory Masking
Natural and artificial sounds can disrupt behavior by masking, or
interfering with, a marine mammal's ability to hear other sounds.
Masking occurs when the receipt of a sound is interfered with by
another coincident sound at similar frequencies and at similar or
higher levels. 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. If the coincident
(masking) sound were man-made, it could be potentially harassing if it
disrupted hearing-related behavior. It is important to distinguish TTS
and PTS, which persist after the sound exposure, from masking, which
occurs during the sound exposure. Because masking (without resulting in
TS) is not associated with abnormal physiological function, it is not
considered a physiological effect, but rather a potential behavioral
effect.
The frequency range of the potentially masking sound is important
in determining any potential behavioral impacts. Because noise
generated from in-water pile driving is mostly concentrated at low
frequency ranges, it may have less effect on high frequency
echolocation sounds made by 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).
Masking has the potential to impact species at population,
community, or even ecosystem levels, as well as at individual levels.
Masking affects both senders and receivers of the signals and can
potentially have long-term chronic effects on marine mammal species and
populations. Recent research suggests that low frequency ambient sound
levels have increased by as much as 20 dB (more than three times in
terms of SPL) in the world's ocean from pre-industrial periods, and
that 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 intensifying masking. However, the
sum of noise from the proposed activities is confined in an area of
inland waters (Hood Canal) that is bounded by landmass; therefore, the
noise generated is not expected to contribute to increased ocean
ambient noise.
The most intense underwater sounds in the proposed action are those
produced by impact pile driving. Given that the energy distribution of
pile driving covers a broad frequency spectrum, sound from these
sources would likely be within the audible range of California sea
lions, harbor seals, transient killer whales, harbor porpoises, and
Dall's porpoises. Impact pile driving activity is relatively short-
term, with rapid pulses occurring for approximately fifteen minutes per
pile. The probability for impact pile driving resulting from this
proposed action masking acoustic signals important to the behavior and
survival of marine mammal species is likely to be negligible. Vibratory
pile driving is also relatively short-term, with rapid oscillations
occurring for approximately one and a half hours per pile. It is
possible that vibratory pile driving resulting from this proposed
action may mask acoustic signals important to the behavior and survival
of marine mammal species, but the short-term duration and limited
affected area would result in a negligible impact from masking. Any
masking event that could possibly rise to Level B harassment under the
MMPA would occur concurrently within the zones of behavioral harassment
already estimated for vibratory and impact pile driving, and which have
already been taken into account in the exposure analysis.
Airborne Noise Effects
Marine mammals that occur in the project area could be exposed to
airborne sounds associated with pile driving that have the potential to
cause harassment, depending on their distance from pile driving
activities. Airborne pile driving noise would have less impact on
cetaceans than pinnipeds because noise from atmospheric sources does
not transmit well underwater (Richardson et al. 1995); thus, airborne
noise would only be an issue for hauled-out pinnipeds in the project
area. Most likely, airborne sound would cause behavioral responses
similar to those discussed above in relation to underwater noise. For
instance, anthropogenic sound could cause hauled-out pinnipeds to
exhibit changes in their normal behavior, such as reduction in
vocalizations, or cause them to temporarily abandon their habitat and
move further from the source. Studies by Blackwell et al. (2004) and
Moulton et al. (2005) indicate a tolerance or lack of response to
unweighted airborne sounds as high as 112 dB peak and 96 dB rms.
Anticipated Effects on Habitat
The proposed activities at NBKB will not result in permanent
impacts to habitats used directly by marine mammals, such as haul-out
sites, but may have potential short-term impacts to food sources such
as forage fish and salmonids. There are no rookeries or major haul-out
sites within 10 km (6.2 mi), foraging hotspots, or other ocean bottom
structure of significant biological importance to marine mammals that
may be present in the marine waters in the vicinity of the project
area. Therefore, the main impact issue associated with the proposed
activity will be temporarily elevated noise levels and the associated
direct effects on marine mammals, as discussed previously in this
document. The most likely impact to marine mammal habitat occurs from
pile driving effects on likely marine mammal prey (i.e., fish) near
NBKB and minor impacts to the immediate substrate during installation
and removal of piles during the pile replacement project.
Pile Driving Effects on Potential Prey (Fish)
Construction activities will produce both pulsed (i.e., impact pile
driving)
[[Page 6422]]
and continuous (i.e., vibratory pile driving) sounds. Fish react to
sounds which are especially strong and/or intermittent low-frequency
sounds. Short duration, sharp sounds can cause overt or subtle changes
in fish behavior and local distribution. Hastings and Popper (2005,
2009) identified several studies that suggest fish may relocate to
avoid certain areas of noise energy. Additional studies have documented
effects of pile driving (or other types of continuous sounds) on fish,
although several are based on studies in support of large, multiyear
bridge construction projects (Scholik and Yan 2001, 2002; Govoni et al.
2003; Hawkins 2005; Hastings 1990, 2007; Popper et al. 2006; Popper and
Hastings 2009). Sound pulses at received levels of 160 dB re 1 [mu]Pa
may cause subtle changes in fish behavior. SPLs of 180 dB may cause
noticeable changes in behavior (Chapman and Hawkins 1969; Pearson et
al. 1992; Skalski et al. 1992). SPLs of sufficient strength have been
known to cause injury to fish and fish mortality (CALTRANS 2001;
Longmuir and Lively 2001). The most likely impact to fish from pile
driving activities at the project area would be temporary behavioral
avoidance of the area. The duration of fish avoidance of this area
after pile driving stops is unknown, but a rapid return to normal
recruitment, distribution and behavior is anticipated. In general,
impacts to marine mammal prey species are expected to be minor and
temporary due to the short timeframe for the pile replacement project.
However, adverse impacts may occur to a few species of rockfish
(bocaccio [Sebastes paucispinis] and yelloweye [S. ruberrimus] and
canary [S. pinniger] rockfish) and salmon (chinook [Oncorhynchus
tshawytscha] and summer run chum) which may still be present in the
project area despite operating in a reduced work window in an attempt
to avoid important fish spawning time periods. Impacts to these species
could result from potential impacts to their eggs and larvae.
Pile Driving Effects on Potential Foraging Habitat
In addition, the area likely impacted by the pile replacement
project is relatively small compared to the available habitat in the
Hood Canal. Avoidance by potential prey (i.e., fish) of the immediate
area due to the temporary loss of this foraging habitat is also
possible. The duration of fish avoidance of this area after pile
driving stops is unknown, but a rapid return to normal recruitment,
distribution and behavior is anticipated. Any behavioral avoidance by
fish of the disturbed area would still leave significantly large areas
of fish and marine mammal foraging habitat in the Hood Canal and nearby
vicinity.
Given the short daily duration of noise associated with individual
pile driving and removal, the short duration of the entire pile
replacement project, and the relatively small areas being affected,
pile driving and removal activities associated with the proposed action
are not likely to have a permanent, adverse effect on any fish habitat,
or populations of fish species. Therefore, pile driving and removal is
not likely to have a permanent, adverse effect on marine mammal
foraging habitat at the project area.
Proposed Mitigation
In order to issue an incidental take authorization (ITA) under
Section 101(a)(5)(D) of the MMPA, NMFS must, where applicable, set
forth the permissible methods of taking pursuant to such activity, and
other means of effecting the least practicable 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 (where relevant).
The modeling results for zones of influence (ZOIs; see ``Estimated
Take by Incidental Harassment'') were used to develop mitigation
measures for pile driving and removal activities at NBKB. The ZOIs
effectively represent the mitigation zone that would be established
around each pile to prevent Level A harassment to marine mammals. While
the ZOIs vary between the different diameter piles and types of
installation or removal methods, the Navy is proposing to establish
mitigation zones for the maximum zone of influence for all pile driving
conducted in support of the pile replacement project. In addition to
the measures described later, the Navy will employ the following
standard mitigation measures:
(a) Conduct briefings between construction supervisors and crews,
marine mammal monitoring team, acoustical monitoring team, and Navy
staff prior to the start of all pile driving activity, and when new
personnel join the work, in order to explain responsibilities,
communication procedures, marine mammal monitoring protocol, and
operational procedures.
(b) Comply with applicable equipment noise standards of the U.S.
Environmental Protection Agency and ensure that all construction
equipment has noise control devices no less effective than those
provided on the original equipment.
(c) For in-water heavy machinery work other than pile driving (if
it exists; e.g., standard barges, tug boats, barge-mounted excavators,
or clamshell equipment used to place or remove material), if a marine
mammal comes within 50 m (164 ft), operations shall cease and vessels
shall reduce speed to the minimum level required to maintain steerage
and safe working conditions.
Shutdown and Buffer Zone
The following measures will apply to the Navy's mitigation through
shutdown and buffer zones:
(a) The Navy will implement a minimum shutdown zone of 50 m (164
ft) radius around all pile driving and removal activity. Shutdown zones
typically include all areas where the underwater SPLs are anticipated
to equal or exceed the Level A (injury) harassment criteria for marine
mammals (180-dB isopleth for cetaceans; 190-dB isopleth for pinnipeds).
In this case, piledriving sounds are expected to attenuate below 180 dB
at distances of 16 m or less, but the 50-m shutdown is intended to
further avoid the risk of direct interaction between marine mammals and
the equipment.
(b) The buffer zone shall include all areas where the underwater
SPLs are anticipated to equal or exceed the 160-dB harassment
isopleths, or where the airborne SPLs are anticipated to equal or
exceed the 100-dB isopleths (for pinnipeds in general) or 90-dB
isopleth (for harbor seals). The radius of this zone will be 501 m
(1,644 ft) at the start of pile driving work, but may be adjusted
according to empirical, site-specific data after the project begins.
The buffer zone distance was set at the largest Level B behavioral
disturbance zone calculated for impact pile driving, which was based on
the calculations for airborne noise for harbor seals. The largest
underwater disturbance threshold (160-dB) was 342 m (1,122 ft). The
size of the 120-dB buffer zone for vibratory pile driving makes
monitoring impracticable (see ``Sound Thresholds''; Tables 5-6; 9).
(c) The shutdown and buffer zones will be monitored throughout the
time required to drive a pile. If a marine mammal is observed entering
the buffer zone, a ``take'' would be recorded and behaviors documented.
However, that pile segment would be completed without cessation, unless
the animal approaches or enters the shutdown zone, at which point all
pile driving activities would be halted.
(d) All buffer and shutdown zones will initially be based on the
distances
[[Page 6423]]
from the source that are predicted for each threshold level. However,
in-situ acoustic monitoring will be utilized to determine the actual
distances to these threshold zones, and the size of the shutdown and
buffer zones will be adjusted accordingly based on received sound
pressure levels.
Visual Monitoring
Impact Installation--Monitoring will be conducted for a minimum 50
m (164 ft) shutdown zone and a 501 m (1,644 ft) buffer zone (Level B
harassment) surrounding each pile for the presence of marine mammals
before, during, and after pile driving activities. The buffer zone was
set at the largest Level B behavioral disturbance zone calculated for
impact pile driving, based on the disturbance calculations for airborne
noise for harbor seals. Monitoring will take place from thirty minutes
prior to initiation through thirty minutes post-completion of pile
driving activities.
Vibratory Installation--Monitoring will be conducted for a minimum
50 m (164 ft) shutdown zone. The 120-dB disturbance criterion predicts
an affected area of 40.3 km\2\ (16 mi\2\). Due to the impracticality of
effectively monitoring such a large area, the Navy intends to monitor a
buffer zone equivalent to the size of the Level B disturbance zone for
impact pile driving (501 m) surrounding each pile for the presence of
marine mammals before, during, and after pile driving activities.
Sightings occurring outside this area will still be recorded and noted
as a take, but detailed observations outside this zone will not be
possible, and it would be impossible for the Navy to account for all
individuals occurring in such a zone with any degree of certainty.
Monitoring will take place from thirty minutes prior to initiation
through thirty minutes post-completion of pile driving activities.
Vibratory and Chipping Removal--Monitoring will be conducted for a
minimum 50 m (164 ft) shutdown zone. As discussed previously, predicted
Level A harassment zones are subsumed by the minimum shutdown zone. As
with vibratory installation, the 120-dB disturbance criterion predicts
affected areas that are impracticable to effectively monitor, and the
Navy intends to monitor a buffer zone equivalent to the size of the
Level B disturbance zone for impact pile driving (501 m) surrounding
each pile for the presence of marine mammals before, during, and after
pile driving activities. Monitoring protocols will be identical to
those discussed for pile installation.
The following additional measures will apply to visual monitoring:
(a) Monitoring will be conducted by qualified observers. A trained
observer will be placed from the best vantage point(s) practicable
(e.g., from a small boat, the pile driving barge, on shore, or any
other suitable location) to monitor for marine mammals and implement
shut-down or delay procedures when applicable by calling for the shut-
down to the hammer operator.
(b) Prior to the start of pile driving activity, the shutdown and
safety zones will be monitored for thirty minutes to ensure that they
are clear of marine mammals. Pile driving or removal will only commence
once observers have declared the shutdown zone clear of marine mammals;
animals will be allowed to remain in the buffer zone (i.e., must leave
of their own volition) and their behavior will be monitored and
documented.
(c) If a marine mammal approaches or enters the shutdown zone
during the course of pile driving or removal operations, pile driving
will be halted and delayed until either the animal has voluntarily left
and been visually confirmed beyond the shutdown zone or thirty minutes
have passed without re-detection of the animal.
Sound Attenuation Devices
Sound attenuation devices will be utilized during all impact pile
driving operations. Impact pile driving is only expected to be required
to proof, or drive the last 10-15 ft (3-4.6 m) of each pile, and any
required proofing will be limited to five days total, no more than one
pile per day, and no more than fifteen minutes per pile. Past
experience has shown that proofing is rarely required at the EHW-1
location. The Navy plans to use a bubble curtain as mitigation for in-
water sound during construction activities. Bubble curtains absorb
sound, attenuate pressure waves, exclude marine life from work areas,
and control the migration of debris, sediments and process fluids.
Acoustic Measurements
Acoustic measurements will be used to empirically verify the
proposed shutdown and buffer zones. For further detail regarding the
Navy's acoustic monitoring plan see ``Proposed Monitoring and
Reporting''.
Timing Restrictions
The Navy has set timing restrictions for pile driving activities to
avoid in-water work when ESA-listed fish populations are most likely to
be present. The in-water work window for avoiding negative impacts to
fish species is July 16-February 15. Further, the Navy has narrowed its
work window to avoid times of year when ESA-listed Steller sea lions
may be present at the project area. Therefore, all pile driving would
only occur between July 16-October 31 of the approved in-water work
window from July 16 through February 15 to minimize the number of fish
exposed to underwater noise and other disturbance, and to avoid times
when Steller sea lions are expected to be present. In consultation with
the USFWS, the Navy has further limited impact pile driving to July 16-
September 30.
Soft Start
The use of a soft-start procedure is believed to provide additional
protection to marine mammals by warning, or providing marine mammals a
chance to leave the area prior to the hammer operating at full
capacity. The pile replacement project will utilize soft-start
techniques (ramp-up and dry fire) recommended by NMFS for impact and
vibratory pile driving. The soft-start requires contractors to initiate
noise from vibratory hammers for fifteen seconds at reduced energy
followed by a one-minute waiting period. This procedure will be
repeated two additional times. For impact driving, contractors will be
required to provide an initial set of three strikes from the impact
hammer at forty percent energy, followed by a one minute waiting
period, then two subsequent three strike sets. No soft-start procedures
exist for pneumatic chipping hammers.
Daylight Construction
Pile driving will only be conducted between two hours post-sunrise
through two hours prior to sunset (civil twilight).
Mitigation Effectiveness
It should be recognized that although marine mammals will be
protected from Level A harassment by the utilization of a bubble
curtain and protected species observers (PSOs) monitoring the near-
field injury zones, mitigation may not be 100 percent effective at all
times in locating marine mammals in the buffer zone. The efficacy of
visual detection depends on several factors including the observer's
ability to detect the animal, the environmental conditions (visibility
and sea state), and monitoring platforms.
All observers utilized for mitigation activities will be
experienced biologists with training in marine mammal detection and
behavior. Due to their specialized training the Navy expects that
visual mitigation will be highly effective. Trained observers have
specific knowledge of marine mammal
[[Page 6424]]
physiology, behavior, and life history, which may improve their ability
to detect individuals or help determine if observed animals are
exhibiting behavioral reactions to construction activities.
The Puget Sound region, including the Hood Canal, only infrequently
experiences winds with velocities in excess of 25 kt (Morris et al.
2008). The typically light winds afforded by the surrounding highlands
coupled with the fetch-limited environment of the Hood Canal result in
relatively calm wind and sea conditions throughout most of the year.
The pile replacement project site has a maximum fetch of 8.4 mi (13.5
km) to the north, and 4.2 mi (6.8 km) to the south, resulting in
maximum wave heights of from 2.85-5.1 ft (0.9-1.6 m) (Beaufort Sea
State (BSS) between two and four), even in extreme conditions (30 kt
winds) (CERC 1984). Visual detection conditions are considered optimal
in BSS conditions of three or less, which align with the conditions
that should be expected for the pile replacement project at NBKB.
Observers will be positioned in locations which provide the best
vantage point(s) for monitoring. This will likely be an elevated
position, providing a better range of viewing angles. Also, the
shutdown and buffer zones have relatively small radii to monitor, which
should improve detectability.
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 effecting the least
practicable 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 by NMFS, NMFS has preliminarily
determined that the proposed mitigation measures provide the means of
effecting the least practicable impact on marine mammal 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 ITA for an activity, Section 101(a)(5)(D) of
the MMPA states that NMFS must, where applicable, 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 ITAs 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 in the proposed action area.
Acoustic Measurements
The Navy will conduct acoustic monitoring for impact driving of
steel piles in order to determine the actual distances to the 190-,
180-, and 160-dB (re 1 [mu]Pa rms) isopleths and to determine the
relative effectiveness of the bubble curtain system at attenuating
noise underwater. The Navy will also conduct acoustic monitoring for
vibratory pile driving and removal, and for removal with a pneumatic
chipping hammer, in order to determine the actual distance to the 120-
dB isopleth for behavioral harassment relative to background levels.
The monitoring plan addresses both underwater and airborne sounds from
the pile replacement project. At a minimum, the methodology will
include:
(1) A stationary hydrophone placed at mid-water depth and 10 m (33
ft) from the source pile to measure the effectiveness of the bubble
curtain system; a weighted tape measure will be used to determine the
depth of the water. The hydrophone will be attached to a nylon cord or
steel chain if current is swift enough, to maintain a constant distance
from the pile. The nylon cord or chain will be attached to a float or
tied to a static line at the surface 10 m from the piles.
(2) All hydrophones will be calibrated at the start of the action
and will be checked at the beginning of each day of monitoring
activity.
(3) For each monitored location, a two-hydrophone setup will be
used, with the first hydrophone at mid-depth and the second hydrophone
at approximately 1 m (3.3 ft) from the bottom in order to evaluate site
specific attenuation and propagation characteristics that may be
present throughout the water column.
(4) In addition to determining the area encompassed by the 190-,
180-, 160-, and 120-db rms isopleths for marine mammals, hydrophones
would also be placed at other distances as appropriate to accurately
capture spreading loss occurring at the EHW-1 project area.
(5) For airborne recordings, a stationary hydrophone will be placed
at 50 ft (15 m) from the source for initial reference recordings.
(6) For airborne measurements, in addition to determining the area
encompassed by the 100 and 90 dB rms isopleths for pinnipeds and harbor
seals, hydrophones will be placed at other distances as appropriate to
accurately capture spreading loss occurring at the EHW-1 project area.
(7) Ambient conditions, both airborne and underwater, would be
measured at the project site in the absence of construction activities
to determine background sound levels. Ambient levels are intended to be
recorded over the frequency range from 10 Hz to 20 kHz. Ambient
conditions will be recorded for one minute every hour of the work day,
for one week of each month of the pile replacement project.
(8) Sound levels associated with soft-start techniques will also be
measured.
(9) Underwater sound pressure levels would be continuously
monitored during the entire duration of each pile being driven. Sound
pressure levels will be monitored in real time. Sound levels will be
measured in Pascals, which are easily converted to decibel units.
(10) Airborne levels would be recorded as unweighted, as well as in
dBA, and the distance to marine mammal thresholds would be measured.
(11) The effectiveness of using a bubble curtain system with a
vibratory hammer will be tested during the driving of two vibratory
piles. The on/off regime described in Table 11 will be utilized during
the pile installation:
Table 11--Schedule for Testing Effectiveness of Sound Attenuation Device
------------------------------------------------------------------------
Sound attenuation device
Pile driving timeframe condition
------------------------------------------------------------------------
Initial 30 s.............................. Off.
Next minute (minimum)..................... On.
Middle of pile driving segment............ Off.
30 s......................................
Next minute (minimum)..................... On.
Final 30 s................................ Off.
------------------------------------------------------------------------
(12) Environmental data will be collected, including, but not
limited to: wind speed and direction, air temperature, humidity,
surface water temperature, water depth, wave height, weather conditions
and other factors
[[Page 6425]]
that could contribute to influencing the airborne and underwater sound
levels (e.g., aircraft, boats).
(13) The chief inspector will supply the acoustics specialist with
the substrate composition, hammer model and size, hammer energy
settings and any changes to those settings during the piles being
monitored, depth of the pile being driven, and blows per foot for the
piles monitored.
(14) Post-analysis of the sound level signals will include
determination of absolute peak overpressure and under pressure levels
recorded for each pile, rms value for each absolute peak pile strike,
rise time, average duration of each pile strike, number of strikes per
pile, SEL of the absolute peak pile strike, mean SEL, and cumulative
SEL (accumulated SEL = single strike SEL + 10*log (number of hammer
strikes) and a frequency spectrum both with and without mitigation,
between 10-20,000 Hz for up to eight successive strikes with similar
sound levels.
Visual Marine Mammal Observations
The Navy will collect sighting data and behavioral responses to
construction for marine mammal species observed in the region of
activity during the period of activity. All observers will be trained
in marine mammal identification and behaviors. NMFS requires that the
observers have no other construction related tasks while conducting
monitoring.
Methods of Monitoring--The Navy will monitor the shutdown zone and
safety (buffer) zone before, during, and after pile driving. Based on
NMFS requirements, the Marine Mammal Monitoring Plan would include the
following procedures for impact pile driving:
(1) MMOs would be located at the best vantage point(s) in order to
properly see the entire shutdown zone and safety zone. This may require
the use of a small boat to monitor certain areas while also monitoring
from one or more land based vantage points.
(2) During all observation periods, observers would use binoculars
and the naked eye to search continuously for marine mammals.
(3) To verify the required monitoring distances, the zones would be
clearly marked with buoys or other suitable aquatic markers.
(4) If the shut down or safety zones are obscured by fog or poor
lighting conditions, pile driving or removal would not be initiated
until all zones are visible.
(5) The shut down and safety zones around the pile will be
monitored for the presence of marine mammals before, during, and after
any pile driving or removal activity.
Pre-Activity Monitoring--The shutdown and buffer zones will be
monitored for thirty minutes prior to initiating the soft start for
pile driving or removal. If marine mammal(s) are present within the
shut down zone prior to pile driving or removal, or during the soft
start, the start of pile driving would be delayed until the animal(s)
leave the shut down zone. Pile driving would resume only after the PSO
has determined, through sighting or by waiting approximately thirty
minutes, that the animal(s) has moved outside the shutdown zone.
During Activity Monitoring--The shutdown and buffer zones will also
be monitored throughout the time required to drive or remove a pile. If
a marine mammal is observed entering the buffer zone, a ``take'' would
be recorded and behaviors documented. However, that pile segment would
be completed without cessation, unless the animal enters or approaches
the shutdown zone, at which point all pile driving activities will be
halted. Pile driving can only resume once the animal has left the
shutdown zone of its own volition or has not been re-sighted for a
period of thirty minutes.
Post-Activity Monitoring--Monitoring of the shutdown and buffer
zones would continue for thirty minutes following the completion of
pile driving.
Data Collection
NMFS requires that the PSOs use NMFS-approved sighting forms. In
addition to the following requirements, the Navy will note in their
behavioral observations whether an animal remains in the project area
following a Level B taking (which would not require cessation of
activity). This information will ideally make it possible to determine
whether individuals are taken (within the same day) by one or more
types of pile driving (i.e., impact and vibratory). NMFS requires that,
at a minimum, the following information be collected on the sighting
forms:
(1) Date and time that pile driving begins or ends;
(2) Construction activities occurring during each observation
period;
(3) Weather parameters identified in the acoustic monitoring (e.g.,
wind, humidity, temperature);
(4) Tide state and water currents;
(5) Visibility;
(6) Species, numbers, and, if possible, sex and age class of marine
mammals;
(7) Marine mammal behavior patterns observed, including bearing and
direction of travel, and if possible, the correlation to sound pressure
levels;
(8) Distance from pile driving activities to marine mammals and
distance from the marine mammals to the observation point;
(9) Locations of all marine mammal observations; and
(10) Other human activity in the area.
Reporting
A draft report would be submitted to NMFS within 45 days of the
completion of acoustic measurements and marine mammal monitoring. The
results would be summarized in graphical form and include summary
statistics and time histories of impact sound values for each pile. A
final report would be prepared and submitted to NMFS within thirty days
following receipt of comments on the draft report from NMFS. At a
minimum, the report shall include:
(1) Size and type of piles;
(2) A detailed description of the SAS or bubble curtain, including
design specifications;
(3) The impact or vibratory hammer force used to drive and extract
the piles;
(4) A description of the monitoring equipment;
(5) The distance between hydrophone(s) and pile;
(6) The depth of the hydrophone(s);
(7) The depth of water in which the pile was driven;
(8) The depth into the substrate that the pile was driven;
(9) The physical characteristics of the bottom substrate into which
the piles were driven;
(10) The ranges and means for peak, rms, and SELs for each pile;
(11) The results of the acoustic measurements, including the
frequency spectrum, peak and rms SPLs, and single-strike and cumulative
SEL with and without the attenuation system;
(12) The results of the airborne noise measurements including dBA
and unweighted levels;
(13) A description of any observable marine mammal behavior in the
immediate area and, if possible, the correlation to underwater sound
levels occurring at that time;
(14) Results, including the detectability of marine mammals,
species and numbers observed, sighting rates and distances, behavioral
reactions within and outside of safety zones; and
(15) A refined take estimate based on the number of marine mammals
observed in the safety and buffer zones. This may be reported as one or
both of the following: a rate of take (number of marine mammals per
hour), or take based on density (number of individuals within the
area).
[[Page 6426]]
Estimated Take by Incidental Harassment
With respect to the activities described 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].
All anticipated takes would be by Level B harassment, involving
temporary changes in behavior. The proposed mitigation and monitoring
measures are expected to minimize the possibility of injurious or
lethal takes such that take by Level A harassment, serious injury or
mortality is considered remote. However, as noted earlier, there is no
specific information demonstrating that injurious or lethal ``takes''
would occur even in the absence of the planned mitigation and
monitoring measures.
If a marine mammal responds to an underwater sound by changing its
behavior or moving a small distance, the response may or may not rise
to the level of ``taking'', or affect the stock or the species as a
whole. However, if a sound source displaces marine mammals from an
important feeding or breeding area for a prolonged period, impacts on
animals or on the stock or species could potentially be significant
(Lusseau and Bejder 2007; Weilgart 2007). Given the many uncertainties
in predicting the quantity and types of impacts of noise on marine
mammals, it is common practice to estimate how many mammals are likely
to be present within a particular distance of a given activity, or
exposed to a particular level of sound. This practice potentially
overestimates the numbers of marine mammals taken. For example, during
the past ten years, killer whales have been observed within the project
area twice. While a pod of killer whales could potentially visit again
during the project timeframe, and thus be ``taken'', it is more likely
that they will not.
The proposed project area is not believed to be particularly
important habitat for marine mammals, nor is it considered an area
frequented by marine mammals, although harbor seals are year-round
residents of Hood Canal. Therefore, behavioral disturbances that could
result from anthropogenic noise associated with the proposed activities
are expected to affect only a small number of marine mammals on an
infrequent basis.
The Navy is requesting authorization for the potential taking of
small numbers of California sea lions, harbor seals, transient killer
whales, Dall's porpoises, and harbor porpoises in the Hood Canal that
may result from pile driving during construction activities associated
with the pile replacement project described previously in this
document. The takes requested are expected to have no more than a minor
effect on individual animals and no effect on the populations of these
species. Any effects experienced by individual marine mammals are
anticipated to be limited to short-term disturbance of normal behavior
or temporary displacement of animals near the source of the noise.
Description of Take Calculation
The take calculations presented here rely on the best data
currently available for marine mammal populations in the Hood Canal, as
discussed in preceding sections. The formula was developed for
calculating take due to impact pile driving and applied to each group-
specific noise impact threshold. The formula is founded on the
following assumptions:
(a) Each species population is at least as large as any previously
documented highest population estimate.
(b) All pilings to be installed would have a noise disturbance
distance equal to the piling that causes the greatest noise disturbance
(i.e., the piling furthest from shore).
(c) Pile driving could potentially occur every day of the in-water
work window. However, it is estimated no more than a few hours of pile
driving will occur per day. An average of two steel piles will be
installed and removed per day or an average of three concrete piles
will be removed per day.
(d) Some degree of mitigation (i.e., sound attenuation system,
etc.) will be utilized, as discussed previously.
(e) An individual can only be taken once per method of installation
during a 24 hr period. The calculation for marine mammal takes is
estimated by:
Take estimate = (n * ZOI) * days of total activity
where:
n = density estimate used for each species/season
ZOI = noise threshold zone of influence (ZOI) impact area; the area
encompassed by all locations where the sound pressure levels equal
or exceed the threshold being evaluated
n * ZOI produces an estimate of the abundance of animals that could
be present in the area for exposure
The ZOI impact area is the estimated range of impact to the noise
criteria. The distances (actual) specified in Tables 5-6 and 9 were
used to calculate ZOI around each pile. All impact pile driving take
calculations were based on the estimated threshold ranges using a
bubble curtain with 10 dB attenuation as a mitigation measure (see
``Underwater Noise from Piledriving''). The ZOI impact area took into
consideration the possible affected area of the Hood Canal from the
pile driving site furthest from shore with attenuation due to land
shadowing from bends in the canal. Because of the close proximity of
some of the piles to the shore, the narrowness of the canal at the
project area, and the maximum fetch, the ZOIs for each threshold are
not necessarily spherical and may be truncated.
While pile driving can occur any day throughout the in-water work
window, only a fraction of that time is actually spent pile driving. On
days when pile driving occurs, it could take place for thirty minutes,
or up to several hours. The contractor estimates that steel pile
installation could occur at a maximum rate of four piles per day;
however, it is more likely that an average of two piles will be
installed and removed per day. The contractor estimates that a maximum
of five concrete piles can be removed per day, with an average of three
being removed per day. For each pile installed, vibratory pile driving
is expected to be no more than one hour. The impact driving portion of
the project is anticipated to take approximately fifteen minutes per
pile, with a maximum of one pile per day, and five piles in total
allowed. All steel piles will be extracted using a vibratory hammer.
Extraction is anticipated to take approximately thirty minutes per
pile. Concrete piles will be removed using a pneumatic chipping hammer
or other similar concrete demolition tool, and it is expected to take
approximately two hours to remove each concrete pile. For steel piles,
this results in a maximum of two hours of pile driving per pile or
potentially four hours per day. For concrete piles, this results in a
maximum of two hours of pneumatic chipping per pile, or potentially six
hours per day.
Therefore, while 108 days of in-water work time is proposed, only a
fraction of the total work time per day will actually be spent pile
driving. An average work day (two hours post-sunrise to two hours prior
to sunset) is approximately eight to nine hours, depending on the
month. While it is anticipated that only four hours of pile driving
would be needed per day for steel piles, or six hours of pneumatic
chipping for concrete piles, to take into
[[Page 6427]]
account deviations from the estimated times for pile installation and
removal the Navy modeled potential impacts as if the entire day could
be spent pile driving.
Based on the proposed action, the total pile driving time from
vibratory pile driving during installation would be approximately
fourteen days (28 piles at an average of two per day). The total pile
driving time from vibratory pile driving during steel pile removal
would be 21 days (42 piles at an average of two per day). The total
pile driving time for utilizing a pneumatic chipping hammer during
concrete pile removal would be 32 days (96 piles at an average of three
per day). Therefore, impacts for installation, steel pile removal, and
concrete pile removal were modeled as if these actions were to occur
throughout the duration of 14, 21, and 32 days, respectively. During
installation, there is the potential for the contractor to need to
utilize an impact hammer to proof a select number of piles, although
past repairs on the EHW-1 pier have never required the use of an impact
pile driver. However, if the use of an impact hammer is required,
impact pile driving will occur on no more than five piles, with only
one pile being impact driven per day. Therefore, impact pile driving
during installation was modeled as occurring for five days.
The exposure assessment methodology is an estimate of the numbers
of individuals exposed to the effects of pile driving activities
exceeding NMFS-established thresholds. Of note in these exposure
estimates, mitigation methods other than the use of a sound attenuation
device (i.e., visual monitoring and the use of shutdown zones) were not
quantified within the assessment and successful implementation of this
mitigation is not reflected in exposure estimates. Results from
acoustic impact exposure assessments should be regarded as conservative
estimates that are strongly influenced by limited biological data.
While the numbers generated from the pile driving exposure calculations
provide conservative overestimates of marine mammal exposures for
consultation with NMFS, the short duration and limited geographic
extent of the pile replacement project would further limit actual
exposures.
California Sea Lion
California sea lions are present in the Hood Canal almost year-
round with the exception of mid-June through August. The Navy conducted
year round waterfront surveys for marine mammals at NBKB in 2008 and
2009 (DoN 2010a). During these surveys, the daily maximum number of
California sea lions hauled out for the months July-October (the
timeframe of the pile replacement project), were 0, 0, 12, and 47 in
2008 and 0, 1, 32, and 44 in 2009, respectively. The monthly average of
the maximum number of California sea lions observed per day was
seventeen individuals. Females are rarely observed north of the
California-Oregon border (NMFS 2008c); therefore only adult and sub-
adult males are expected in the Hood Canal. Breeding rookeries are in
California; therefore pups are not expected to be present in the Hood
Canal.
California sea lions are not likely to be present at the project
site during the entire period of work (i.e., are infrequent visitors
during July-August). However, because the proportion of pile driving
that could occur in a given month is dependent on several factors
(e.g., availability of materials, weather) the Navy assumed that pile
driving operations could occur at any time in the construction window.
Therefore, exposures were calculated using the monthly average of the
maximum number of California sea lions observed per day (seventeen
individuals), divided by the area encompassed by the maximum fetch at
the project site (41.5 km\2\ [16 mi\2\]) and the formula given
previously. Table 12 depicts the number of acoustic harassments that
are estimated from vibratory and impact pile driving and removal, and
pneumatic chipping, both underwater and in-air for each season. The
modeling indicated that zero California sea lions were likely to be
exposed to sound in the 160-dB zone. However, the Navy feels that,
based on the abundance of this species in the waters along NBKB and
including their presence at nearby haul-outs, it is possible that an
individual could pass through this zone in transit to or from a haul-
out. Therefore, the Navy is requesting a behavioral harassment take of
California sea lion by impact pile driving each day of pile driving,
for a total of five takes over the course of the proposed action.
Harbor Seal
Harbor seals are present in the Hood Canal year-round and would be
expected at the project site. Harbor seal numbers increase from January
through April and then decrease from May through August as the harbor
seals move to adjacent bays on the outer coast of Washington for the
pupping season. Harbor seals are the most abundant marine mammal in the
Hood Canal. Jeffries et al. (2003) did a stock assessment of harbor
seals in the Hood Canal in 1999 and counted 711 harbor seals hauled
out. This abundance was adjusted using a correction factor of 1.53 to
account for seals in the water and not counted to provide a population
estimate of 1,088 harbor seals in the Hood Canal. The Navy conducted
boat surveys of the waterfront area in 2008 from July to September
(Agness and Tannenbaum 2009a). Harbor seals were sighted during every
survey and were found in all marine habitats including near and hauled-
out on man-made objects such as piers and buoys. During most of the
year, all age and sex classes (except newborn pups) could occur in the
project area throughout the period of construction activity. From April
through mid-July, female harbor seals haul out on the outer coast of
Washington at pupping sites to give birth. Since there are no known
pupping sites in the vicinity of the project, harbor seal pups are not
expected to be present during pile driving. The main haul-out locations
for harbor seals in Hood Canal are located on river delta and tidal
exposed areas at Quilcene, Dosewallips, Duckabush, Hamma Hamma, and
Skokomish River mouths, with the closest haul-out area to the project
area being 10 mi (16 km) southwest of NBKB at Dosewallips River mouth
(London 2006). Please see Figure 4-1 of the Navy's application for a
map of haul-out locations in relation to the project area.
Research by Huber et al. (2001) indicates that approximately 35
percent of harbor seals are in the water at any one time. Exposures
were calculated using a density derived from the number of harbor seals
that are present in the water at any one time (35 percent of 1,088, or
approximately 381 individuals), divided by the area of the Hood Canal
(291 km\2\ [112 mi\2\]) and the formula presented previously.
While Huber et al.'s (2001) data suggest that harbor seals
typically spend 65 percent of their time hauled out, the Navy's
waterfront surveys found that it is extremely rare for harbor seals to
haul out in the vicinity of the test pile project area. Therefore, the
only population of harbor seals that could potentially be exposed to
airborne sounds are those that are in-water but at the surface. Based
on the diving cycle of tagged harbor seals near the San Juan Islands,
the Navy estimates that seals are on the surface approximately 16.4
percent of their total in-water duration (Suryan and Harvey 1998).
Therefore, by multiplying the percentage of time spent at the surface
(16.4 percent) by the total in-water population of harbor seals at any
one time (approximately 381 individuals), the population of harbor
[[Page 6428]]
seals with the potential to experience airborne impacts (approximately
63 individuals) can be obtained. Airborne exposures were calculated
using a density derived from the maximum number of harbor seals
available at the surface (approximately 63 individuals), divided by the
area of the Hood Canal (291 km\2\) and the formula presented
previously. Table 12 depicts the number of acoustic harassments that
are estimated from vibratory and impact pile driving and removal, and
from pneumatic chipping, both underwater and in-air for each season.
The modeling indicated that zero harbor seals were likely to be exposed
to sound in the 160-dB zone. However, the Navy feels that, based on the
abundance of this species in the waters along NBKB and including their
presence at nearby haul-outs, it is possible that an individual could
pass through this zone in transit to or from a haul-out. Therefore, the
Navy is requesting a behavioral harassment take of harbor seal by
impact pile driving each day of pile driving, for a total of five takes
over the course of the proposed action.
Killer Whales
Transient killer whales are uncommon visitors to Hood Canal.
Transients may be present in the Hood Canal anytime during the year and
traverse as far as the project site. Resident killer whales have not
been observed in Hood Canal, but transient pods (six to eleven
individuals per event) were observed in Hood Canal for lengthy periods
of time (59-172 days) in 2003 (January-March) and 2005 (February-June),
feeding on harbor seals (London 2006).
These whales used the entire expanse of Hood Canal for feeding.
Subsequent aerial surveys suggest that there has not been a sharp
decline in the local seal population from these sustained feeding
events (London 2006). Based on this data, the density for transient
killer whales in the Hood Canal for January to June is 0.038/km\2\
(0.015/mi\2\; eleven individuals divided by the area of the Hood Canal
[291 km\2\]). Since this timeframe overlaps the period in which the
pile replacement project will occur (July-October), this density was
used for all exposure calculations. Exposures were calculated using the
formula presented previously. Table 12 depicts the number of acoustic
harassments that are estimated from vibratory and impact pile driving
for each season. The modeling indicated that zero killer whales were
likely to be exposed to sound in the 160-dB zone. However, while
transient killer whales are rare in the Hood Canal, when these animals
are present they occur in pods, so their density in the project area is
unlikely to be uniform, as was modeled. If they are present during
impact pile driving it is possible that one or more individuals within
a pod could travel through the behavioral harassment zone. Therefore,
the Navy is requesting nine behavioral takes of transient killer
whales--based on the average size of pods seen previously in the Hood
Canal--by impact pile driving over the course of the proposed action.
Dall's Porpoise
Dall's porpoises may be present in the Hood Canal year-round and
could occur as far as the project site. Their use of inland Washington
waters, however, is mostly limited to the Strait of Juan de Fuca. The
Navy conducted boat surveys of the waterfront area in 2008 from July to
September (Agness and Tannenbaum 2009a). During one of the surveys a
Dall's porpoise was sighted in August in the deeper waters off Carlson
Spit.
In the absence of an abundance estimate for the entire Hood Canal,
a seasonal density (warm season only) was derived from the waterfront
survey by the number of individuals seen divided by total number of
kilometers of survey effort (six surveys with approximately 3.9 km\2\
[1.5 mi\2\] of effort each), assuming strip transect surveys. In
absence of any other survey data for the Hood Canal, this density is
assumed to be throughout the project area. Exposures were calculated
using the formula presented previously. Table 12 depicts the number of
acoustic harassments that are estimated from vibratory and impact pile
driving for each season. The modeling indicated that zero Dall's
porpoises were likely to be exposed to sound in the 160-dB zone. Dall's
porpoises are rare in the Hood Canal; only one animal, seen in deep
waters offshore from the base, has been seen in the project area in the
past few years. However, it is possible that additional animals exist
or that this single individual could pass through the behavioral
harassment zone for impulse sounds (160-dB) while transiting along the
waterfront. Therefore, the Navy is requesting a single behavioral
harassment take of a Dall's porpoise by impact pile driving over the
course of the proposed action.
Harbor Porpoise
Harbor porpoises may be present in the Hood Canal year-round;
however, their presence is rare. During waterfront surveys of NBKB over
the past two years (2008-present) only one harbor porpoise has been
seen in 24 surveys.
The Navy conducted boat surveys of the waterfront area from July to
September over the past few years (2008-present) (Agness and Tannenbaum
2009a). During one of the surveys a single harbor porpoise was sighted
in the deeper waters offshore from the waterfront. In the absence of an
abundance estimate for the entire Hood Canal, a seasonal density (warm
season only) was derived from the waterfront survey by the number of
individuals seen divided by total number of kilometers of survey effort
(24 surveys with approximately 3.9 km\2\ [1.5 mi\2\] of effort each),
assuming strip transect surveys. In the absence of any other survey
data for the Hood Canal, this density is assumed to be throughout the
project area. Exposures were calculated using the formula presented
previously; Table 12 depicts the number of acoustic harassments that
are estimated from vibratory and impact pile driving for each season.
The modeling indicated that zero harbor porpoises were likely to be
exposed to sound in the 120-dB zone. However, while harbor porpoises
are rare, one has been sighted in surveys over the last few years in
the deep waters offshore from the base. It is possible this offshore
region is encapsulated within the disturbance zone during vibratory
pile installation and removal due to the large size (40.3 [15.6] and
35.9 km\2\ [13.9 mi\2\], respectively). Therefore, based on the
possibility that this animal could be present in the offshore waters
during every day of construction, the Navy is requesting a single
behavioral take of harbor porpoise by vibratory pile driving each day
of pile driving, for a total of 35 takes over the course of the
proposed action (fourteen during installation and 21 during removal).
The area of disturbance during pneumatic chipping is comparatively
small (0.608 km\2\ [0.23 mi\2\]); thus, the Navy does not feel harbor
porpoises are likely to occur in this area and is not requesting take
for pneumatic chipping.
Potential takes could occur if individuals of these species move
through the area on foraging trips when pile driving or removal is
occurring. Individuals that are taken could exhibit behavioral changes
such as increased swimming speeds, increased surfacing time, or
decreased foraging. Most likely, individuals may move away from the
sound source and be temporarily displaced from the areas of pile
driving or removal. Potential takes by disturbance would have a
negligible short-term effect on individuals and would not result in
population-level impacts.
[[Page 6429]]
Table 12--Number of Potential Warm Season (May-Oct) Exposures of Marine Mammals Within Various Acoustic Threshold Zones
--------------------------------------------------------------------------------------------------------------------------------------------------------
Underwater Airborne
---------------------------------------------------------------- Total (percent
Impact Vibratory Impact & of stock or
Species Density Impact injury disturbance disturbance vibratory population
threshold \1\ threshold (160 threshold (120 disturbance \3\)
dB) dB) threshold \2\
--------------------------------------------------------------------------------------------------------------------------------------------------------
California sea lion..................................... 0.410 0 \*\ 5 553 0 558 (0.2)
Harbor seal............................................. 1.31 0 \*\ 5 1,761 \4\ 0 1,766 (12.1)
Killer whale............................................ 0.038 0 \*\ 9 49 N/A 58 (18.5)
Dall's porpoise......................................... 0.043 0 \*\ 1 70 N/A 71 (0.1)
Harbor porpoise......................................... 0.011 0 0 \*\ 35 N/A 35 (0.3)
-----------------------------------------------------------------------------------------------
Total............................................... .............. 0 20 2,468 0 2,488
--------------------------------------------------------------------------------------------------------------------------------------------------------
\*\ See species descriptions for discussion of these estimates.
\1\ Acoustic injury threshold for impact pile driving is 190 dB for pinnipeds and 180 dB for cetaceans.
\2\ Acoustic disturbance threshold is 100 dB for California sea lions and 90 dB for harbor seals. The airborne exposure calculations assume that 100% of
the in-water densities were available at the surface to be exposed to airborne sound.
\3\ See Table 10 for stock or population numbers.
\4\ Airborne densities were based on the percentage (16.4 percent) of in-water density available at the surface to be exposed (Suryan and Harvey 1998).
During the project timeframe, which occurs entirely in the May to
October warm season, there is the potential for twenty Level B
disturbance takes (160-dB, impulse sound) of various species from
impact pile driving operations, and an additional 2,468 Level B
disturbance takes (120-dB, continuous sound) of various species from
vibratory pile driving, vibratory removal, and pneumatic chipping due
to underwater sound. The following species and numbers of Level B
disturbance takes could occur due to underwater sound as a result of
impact pile driving operations: five California sea lions, five harbor
seals, nine transient killer whales, and one Dall's porpoise. The
following species and numbers of Level B disturbance takes could occur
due to underwater sound as a result of vibratory pile driving
operations: 553 California sea lions, 1,761 harbor seals, 49 transient
killer whales, seventy Dall's porpoises, and 35 harbor porpoises. Due
to their lack of presence within the project area during the timeframe
for the pile replacement project (July 16-Oct 31), no Steller sea lions
would be harassed. Lastly, no species of pinnipeds are expected to be
exposed to airborne sound pressure levels that would cause harassment.
Negligible Impact and Small Numbers Analysis and Preliminary
Determination
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.'' In making a negligible impact determination,
NMFS considers a variety of factors, including but not limited to: (1)
The number of anticipated mortalities; (2) the number and nature of
anticipated injuries; (3) the number, nature, intensity, and duration
of Level B harassment; and (4) the context in which the take occurs.
Pile driving activities associated with the pile replacement
project, as outlined previously, have the potential to disturb or
displace small numbers of marine mammals. Specifically, the proposed
activities may result in take, in the form of Level B harassment
(behavioral disturbance) only, from airborne or underwater sounds
generated from pile driving. Level A harassment is not anticipated
given the methods of installation and measures designed to minimize the
possibility of injury to marine mammals. Specifically, vibratory
hammers will be the primary method of installation, which are not
expected to cause injury to marine mammals due to the relatively low
source levels (less than 190 dB). Pile removal activities, whether
vibratory removal of steel piles or pneumatic chipping of concrete
piles, produce sound levels lower than those produced by vibratory
installation. Also, no impact pile driving will occur without the use
of a noise attenuation system (e.g., bubble curtain), and pile driving
will either not start or be halted if marine mammals approach the
shutdown zone (described previously in this document). Furthermore, the
pile driving activities analyzed are similar to other nearby
construction activities within the Hood Canal, such as test piles
driven in 2005 for the Hood Canal Bridge (SR-104) constructed by the
Washington Department of Transportation, which have taken place with no
reported injuries or mortality to marine mammals.
NMFS has preliminarily determined that the impact of the previously
described pile replacement project may result, at worst, in a temporary
modification in behavior (Level B harassment) of small numbers of
marine mammals. No mortality or injuries are anticipated as a result of
the specified activity, and none are proposed to be authorized.
Additionally, animals in the area are not expected to incur hearing
impairment (i.e., TTS or PTS) or non-auditory physiological effects.
For pinnipeds, the absence of any major rookeries and only a few
isolated haul-out areas near or adjacent to the project site means that
potential takes by disturbance will have an insignificant short-term
effect on individuals and would not result in population-level impacts.
Similarly, for cetacean species the absence of any regular occurrence
adjacent to the project site means that potential takes by disturbance
will have an insignificant short-term effect on individuals and would
not result in population-level impacts. Due to the nature, degree, and
context of behavioral harassment anticipated, the activity is not
expected to impact rates of recruitment or survival. While modeling
indicates that the specified activities could potentially take, by
harassment only, as many as 58 transient killer whales (18.5 percent of
the regional stock), it is extremely unlikely that 58 individual whales
would be exposed to sound associated with the project. Rather, the
estimated 58 takes represents a single group of nine whales that could
potentially be exposed to sound on multiple days, if present. As such,
the possible repeated
[[Page 6430]]
exposure of a small group of individuals does not present the
deleterious effect on the regional stock that is suggested by the
figure of 18.5 percent. This activity is expected to result in a
negligible impact on the affected species or stocks. None of the
species for which take authorization is requested are either ESA-listed
or considered depleted under the MMPA.
For reasons stated previously in this document, the negligible
impact determination is also supported by the likelihood that, given
sufficient ``notice'' through mitigation measures including soft start,
marine mammals are expected to move away from a noise source that is
annoying prior to its becoming potentially injurious, and the
likelihood that marine mammal detection ability by trained observers is
high under the environmental conditions described for Hood Canal,
enabling the implementation of shut-downs to avoid injury, serious
injury, or mortality. As a result, no take by injury or death is
anticipated, and the potential for temporary or permanent hearing
impairment is very low and will be avoided through the incorporation of
the proposed mitigation measures.
While the number of marine mammals potentially incidentally
harassed will depend on the distribution and abundance of marine
mammals in the vicinity of the survey activity, the number of potential
harassment takings is estimated to be small relative to regional stock
or population number, and has been mitigated to the lowest level
practicable through incorporation of the proposed mitigation and
monitoring measures mentioned previously in this document.
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 the proposed pile replacement
project will result in the incidental take of small numbers of marine
mammal, by Level B harassment only, and that the total taking from the
activity will have a negligible impact on the affected species or
stocks.
Impact on Availability of Affected Species or Stock for Taking for
Subsistence Uses
No Tribal subsistence hunts are held in the vicinity of the project
area; thus, temporary behavioral impacts to individual animals would
not affect any subsistence activity. Further, no population or stock
level impacts to marine mammals are anticipated or authorized. As a
result, no impacts to the availability of the species or stock to the
Pacific Northwest treaty Tribes are expected as a result of the
proposed activities. Therefore, no relevant subsistence uses of marine
mammals are implicated by this action.
Endangered Species Act (ESA)
There is one marine mammal species that is listed as endangered
under the ESA with confirmed or possible occurrence in the study area:
the Eastern DPS of the Steller sea lion. However, as described
previously, the pile driving and removal activities associated with the
project will occur from July 16-October 31 only, a time at which
Steller sea lions are not present in the project area. The Navy
conducted an informal consultation with the NWRO under Section 7 of the
ESA; the NWRO concurred that there would be no presence of ESA-listed
marine mammals during the project and that formal consultation was not
required.
National Environmental Policy Act (NEPA)
In December 2010, the Navy prepared a draft EA, which has been
posted on the NMFS Web site (see ADDRESSES) concurrently with the
publication of this proposed IHA and public comments have been
solicited. NMFS will review the draft EA and the public comments
received and subsequently either adopt it or prepare its own NEPA
document before making a determination on the issuance of an IHA.
Proposed Authorization
As a result of these preliminary determinations, NMFS proposes to
authorize the take of marine mammals incidental to the Navy's pile
replacement project, provided the previously mentioned mitigation,
monitoring, and reporting requirements are incorporated.
Dated: January 31, 2011.
James H. Lecky,
Director, Office of Protected Resources, National Marine Fisheries
Service.
[FR Doc. 2011-2530 Filed 2-3-11; 8:45 am]
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