Takes of Marine Mammals Incidental to Specified Activities; Manette Bridge Replacement in Bremerton, Washington, 13502-13514 [2010-6248]

Agencies

• DEPARTMENT OF COMMERCE
• National Oceanic and Atmospheric Administration

[Federal Register Volume 75, Number 54 (Monday, March 22, 2010)]
[Notices]
[Pages 13502-13514]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2010-6248]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

RIN 0648-XU03


Takes of Marine Mammals Incidental to Specified Activities; 
Manette Bridge Replacement in Bremerton, Washington

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 Washington State 
Department of Transportation (WSDOT) for an Incidental Harassment 
Authorization (IHA) to take marine mammals, by harassment, incidental 
to construction and demolition activities related to the replacement of 
the Manette Bridge in Bremerton, Washington. Pursuant to the Marine 
Mammal Protection Act (MMPA), NMFS is requesting comments on its 
proposal to issue an IHA to WSDOT to incidentally harass, by Level B 
Harassment only, three species of marine mammals during the specified 
activity.

DATES:  Comments and information must be received no later than April 
21, 2010.

ADDRESSES:  Comments on the application should be addressed to Michael 
Payne, Chief, Permits, Conservation and Education Division, Office of 
Protected Resources, National Marine Fisheries Service, 1315 East-West 
Highway, Silver Spring, MD 20910-3225. The mailbox address for 
providing email comments is 0648-XU03@noaa.gov. 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 https://www.nmfs.noaa.gov/pr/permits/incidental.htm without change. All Personal Identifying Information 
(for example, name, address, etc.) voluntarily submitted by the 
commenter may be publicly accessible. Do not submit Confidential 
Business Information or otherwise sensitive or protected information.
    A copy of the 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: https://www.nmfs.noaa.gov/pr/permits/incidental.htm. Documents cited in this 
notice may also be viewed, by appointment, during regular business 
hours, at the aforementioned address.

FOR FURTHER INFORMATION CONTACT:  Shane Guan, Office of Protected 
Resources, NMFS, (301) 713-2289, ext 137.

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 United States can apply for an authorization 
to incidentally take small numbers of marine mammals by harassment. 
Section 101(a)(5)(D) establishes a 45-

[[Page 13503]]

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 24, 2009, from WSDOT for 
the taking, by harassment, of marine mammals incidental to construction 
and demolition work related to the Manette Bridge replacement in 
Bremerton, Washington, starting in early June 2010.
    The Manette Bridge is located within the Puget Sound of Washington 
State, at the outlet to the Port Washington Narrows. The Port 
Washington Narrows provides the only outlet from Dyes Inlet to Sinclair 
Inlet, and connection to the greater Puget Sound. The Manette Bridge is 
determined to be a functionally obsolete and structurally deficient 
bridge that requires replacement, and the WSDOT is planning to have it 
replaced. The proposed bridge replacement work includes the following 
activities:
     Construction of temporary work trestles, which involves 
steel pile installation using both vibratory and impact driving 
methods;
     Construction of new bridge piers, which involves 
excavation of benthic material;
     Barge anchoring and usage;
     Removal of existing bridge; and
     Removal of temporary work platforms.
    Since marine mammal species and stocks in the proposed action area 
could be affected by the proposed bridge replacement activities, the 
WSDOT is seeking an IHA that would allow the incidental, but not 
intentional, take of marine mammals by Level B behavioral harassment 
during the construction of the new Manette Bridge and removal of the 
existing bridge. The WSDOT states that small numbers of three species 
of marine mammals could potentially be taken by pile driving or other 
construction activities associated with the bridge replacement work. 
However, with the proposed mitigation and monitoring measures, the 
numbers and levels of marine mammal takes would be reduced to the least 
amount practicable.

Description of the Specific Activity

    The Manette Bridge was originally built in 1930. The bridge was 
constructed with five steel truss main spans on six concrete piers, 
elements which are still part of today's bridge. A 1949 contract 
replaced the original wooden deck and timber trusses in the outer spans 
with concrete and steel. The primary areas of structural deficiencies 
are in the concrete piers and the structural steel trusses, which are 
nearing 80 years old. The concrete in the foundations is in varying 
states of deterioration. Testing and analysis of concrete taken from 
the main piers by WSDOT from 1976 through 2003 determined that 
deterioration in the concrete has resulted from a process called Alkali 
Silica Reaction (ASR).
    ASR causes deterioration of mortars and concretes due to the 
swelling of gel formed by the reaction of alkali in cement-based 
materials with reactive silica in aggregates in the presence of water. 
The swelling of the gel generates tensile stresses in the specimen 
resulting in expansion and cracks. There is no known way to mitigate 
and fully address the ASR problem in the concrete foundations of the 
six piers supporting the steel truss spans.
    Overall, the WSDOT determined that the substructure components of 
the existing Manette Bridge are in poor condition at the main piers 
(built in 1930) and in satisfactory condition at the approach piers 
(built in 1949). Columns and pier walls at the main spans exhibit 
leaching cracks, rust stains, delaminations, soft concrete, and 
formwork holes. Exposed rebar is visible above and below the tidal 
zone, however mass marine growth prevents an exact detailing of this 
exposure.
    The foundation is exposed at all piers in varying degrees. Main 
Piers 2 and 3 are in the worst condition with the original footing and 
seals now indeterminate from each other. At the corners, corroded 
remnants of rebar are visible where the footings have been rounded to 
an approximate 4-ft (1.22-m) radius. Several cofferdams have been 
constructed around the different piers to shore up soft concrete. Some 
undermining is occurring at these piers due to local scour conditions.
    Contract repairs to the main concrete piers were completed in 1949 
(Piers 4 and 6) and 1991 (Pier 5) and 1996 (Piers 4 and 6). These 
repairs attempted to encase the deteriorating concrete in the concrete 
foundations but were not effective since the core concrete with ASR 
continues to deteriorate.
    In 1993, the WSDOT Bridge Engineer identified that the bridge 
superstructure (trusses and deck) could be rehabilitated to provide 20 
or more years of additional service life. The cost to totally 
rehabilitate this bridge by: encasing and repairing all the concrete 
main piers; replacing corroded steel including rivets and connections; 
repainting the entire bridge and replacing the bridge deck could exceed 
50-75% of the replacement costs. However, there are no practical means 
to restore or prevent further deterioration in the column and footing 
concrete. The condition of the reinforcing steel in the highly 
fractured substructure concrete is an added unknown. As a result of 
this assessment, the WSDOT determined that replacement of the bridge is 
warranted and necessary.
    The proposed bridge replacement project would replace the 
structurally deficient and functionally obsolete Manette Bridge in the 
City of Bremerton with a new concrete bridge. The new Manette Bridge 
would be built parallel to, and immediately south of, the existing 
bridge with roadway connections to existing city street intersections 
on each end of the bridge. Construction of the project is proposed to 
begin in 2010 and continue for approximately 3 years.
    The project would occur in three main phases. Construction sequence 
plan sheets are included in Appendix A of the WSDOT IHA application. 
First, the new bridge piers and central portion of the new bridge will 
be constructed. Second, the outermost spans of the existing bridge will 
be removed and the new bridge's outermost spans and abutments will be 
built. This work includes the completion of stormwater facilities for 
the new bridge. Finally, the remaining portions of the existing bridge 
will be demolished and removed. The construction elements associated 
with these phases are summarized below.
    The construction of the new bridge would require the construction 
of new piers and demolition of existing piers, all of which include 
work below the mean lower low water (MLLW) mark. An estimated 3,900 
cubic yards of concrete would be placed below the MLLW mark for the new 
bridge piers. Temporary work trestles would be built in Port Washington 
Narrows as part of this project to support both the construction of the 
new bridge and demolition of the existing bridge. This

[[Page 13504]]

also would include work below the MLLW mark. Barges would be used to 
transport and stage equipment and materials. They would be tethered 
with mooring lines and temporarily anchored buoys.
    The footprint of the proposed approaches and abutments is primarily 
located within the existing bridge footprint. However, an additional 
0.75 acre of land would be temporarily disturbed during construction 
and 0.15 acre of land would be permanently converted to roadway.
    Work trestle construction would include pile driving and falsework 
bents. Conceptual work/demolition trestle plan sheets are included in 
Appendix B and D of the WSDOT IHA application.
    The proposed project would construct 1.789 acre of new impervious 
surface (bridge and approaches) and would remove 1.133 acres of 
existing impervious surface, with a net increase of 0.656 acre. Runoff 
from the proposed project would be treated via the City of Bremerton 
stormwater facilities. In addition to treating the runoff from the new 
bridge, the stormwater system would treat runoff from an additional 
0.81 acre of existing impervious surface, the stormwater from which is 
currently discharged untreated into Sinclair Inlet.
    The following is a description of the sequence of anticipated work 
activities associated with the Manette Bridge replacement project.

1. Construction of Work Trestles and Falsework Towers

    Separate work trestles would be constructed for the new bridge 
construction and existing bridge removal processes. The south trestles 
for access to the new bridge site would be constructed prior to the 
installation of the north trestles for bridge removal. The work 
trestles and associated falsework towers would be supported on steel 
pilings with diameters of 24 to 36 in. (0.61 to 0.91 m). The 
construction of the work trestles is estimated to take up to 9 months. 
The work trestles and falsework towers would be in place throughout the 
project duration, approximately 3 years.
    The trestles would be located a few feet above the high water mark, 
with the exact height determined by the contractor and work site 
conditions. The trestles would be supported by steel girders attached 
to the piles and the deck would be composed of timbers. The new bridge 
construction work trestle would be supported by up to 360 piles and 
could cover an area of up to 40,000 ft\2\ (3,716 m\2\). The bridge 
removal work trestle will be supported by up to 170 piles and could 
cover an area of up to 15,900 ft\2\ (1,477 m\2\). Up to 12 additional 
piles may be used for project related moorage.
    All piles would be installed using a vibratory hammer unless an 
impact hammer is needed to drive a pile through consolidated material 
or meet bearing. Currently, pile driving is scheduled to occur July 1 
to August 20, 2010, and October 6, 2010, to January 31, 2011, with an 
estimated 45 minutes per pile and 410 total hours of pile driving using 
a vibratory hammer. Pile driving activities would occur daily two hours 
after sunrise to two hours before sunset between April 1 and September 
15, 2010. No pile driving will occur during nighttime hours.
    Pile driving activities generate intense sound underwater, which 
could potentially impact marine mammal species in the project vicinity. 
For pile driving using an impact hammer, the driver consists of a heavy 
hydraulic hammer that falls by gravity to drive down the piling. 
Intense impulsive sounds with rapid rise time are generated with each 
hammer strike. Although each impulse is short (lasts for dozens of 
milliseconds), the sound pressure levels (SPLs) are extremely high and 
could exceed 200 dB re 1 microPa (peak) at 1 m. The source SPLs of 
impact pile driving depend on the size of the hammer, diameter of the 
piles to be driven, and substrate. For the impact hammer that would be 
used in the Manette Bridge replacement activities, the WSDOT used the 
data from the recent Washington State Ferries impact pile driving 
projects and showed that the source SPLs could be as high as 214 dB re 
1 microPa (peak) at 1 m. Noises generated from impact pile driving are 
broadband (contains a wide spectrum of frequency) but major energy is 
concentrated between 200 1,000 Hz with less energy at higher 
frequencies.
    Unlike pile driving using impact hammers, vibratory pile driving is 
achieved by means of a variable eccentric vibrator attached to the head 
of the pile. The installation process begins by placing a choker around 
the pile and lifting it into vertical position with the crane. The pile 
would then be lowered into position and set in place at the mudline. 
The pile would be held steady while the vibratory hammer installs the 
pile to the required tip elevation. Measured noise levels for similar 
projects conducted by the California Department of Transportation 
(CALTRANS) and WSDOT show that source levels are around 180-195 dB re 1 
microPa (peak) at 1 m. Since underwater SPLs are expressed in terms of 
decibel in reference to acoustic pressure of 1 microPa, the 19 dB 
difference between the source levels from impact pile driving (214 dB 
re 1 microPa) and vibratory pile driving (195 dB re 1 microPa) 
translates into more than three times the difference in acoustic 
pressure. Therefore, vibratory pile driving is much ``quieter'' than 
impact pile driving. However, because the transient sound produced by 
vibratory pile driving has a longer duration than impact pile driving 
pulses, it is arguable that a single batch of vibratory pile driving 
noise could contain more acoustic energy than a single impact hammer 
pulse in terms of sound exposure levels (SEL).

2. Barge Anchoring and Usage

    Barges would be used extensively throughout the project duration to 
provide access to work areas, support machinery, deliver and stage 
materials, and as a collection surface for spoils, construction debris, 
and materials from demolition. The actual number and dimensions of 
barges to be used would be determined by the contractor and work site 
conditions. However, it is estimated that up to 6 barges would be used 
at one time. A typical barge dimension is approximately 290 ft (88.4 m) 
in length and 50 ft (15.2 m) in width. Typical barge draft is 4 to 8 ft 
(1.22 to 2.44 m) and typical freeboard is 3 to 6 ft (0.91 to 1.83 m). 
Barges would be used throughout the construction period, approximately 
3 years.
    During working hours, barges would be attached to mooring lines, 
the work trestles, or to other portions of the project area, depending 
on the construction and access needs. Up to 6 temporary buoys may be 
installed to moor barges during non-working hours. These buoys would be 
attached to one or more anchors, which may need to be driven, or 
excavated, due to hard ground and strong currents in the project area. 
If the contractor chooses to deploy a dynamic barge positioning system, 
it is expected that the hours the system is in use would coincide 
closely with pile driving activities.
    Noise produced from a moored barge is not likely to be significant 
enough to affect marine mammals. However, if a dynamic positioning (DP) 
system is applied to stabilize the barge, sound generated by the DP 
system could be strong enough to adversely affect marine mammals in the 
vicinity. The intensity of the DP system would depend on the size of 
the vessel and the system output, nevertheless, its loudness is not 
likely to surpass that from vibratory pile driving at the same 
distances.

[[Page 13505]]

3. Construction of New Piers

    Eight piers would support the new bridge, six in-water and two 
upland. The existing bridge has 13 piers, nine in-water and three 
upland. The total footprint of the piers would be 1,416 ft\2\ (131.6 
m\2\). The footprint of the nine in-water piers supporting the existing 
bridge is 8,726 ft\2\ (810.7 m\2\).
    Piers 1 and 8 are the bridge abutments and are located well above 
the mean high water line (MHW). Piers 2 through 7 are located below the 
MLLW line. The construction of the in-water piers (2 through 7) would 
take up to 18 months. The construction of the abutment piers (1 and 8) 
would occur during the bridge closure period (targeted duration of 3 
months). The construction of each would include excavation of up to 3 
shafts to support each pier, concrete pouring of each shaft, and 
construction of piers on top of new shafts.
    Shaft casings would be installed and the shafts will be excavated 
using equipment positioned on the work trestles or barges.
    To create a drilled shaft, a steel casing approximately 6 to 10 ft 
(1.8 to 3 m) in diameter is driven into the substrate using a vibratory 
hammer, and the material inside the casing is excavated using an auger 
or a clamshell dredge. During excavation a premixed bentonite or 
synthetic polymer slurry is sometimes added to stabilize the walls of 
the shaft. Spoils from shaft excavation would be placed in a large 
steel containment box located on a barge or on the work trestle for 
offsite transport. During the drilling, polymer slurry is typically 
placed into the hole to keep side walls of the shaft from caving.
    After completion of the excavation, a steel reinforcing cage is 
placed into the hole to specified elevations. Concrete is then pumped 
into the hole using a tremie tube placed at the bottom of the 
excavation. As concrete is placed the tremie tube is raised but is 
maintained within the concrete. As the concrete is pumped into the 
hole, the slurry is displaced upward and removed from the top concrete 
using a vacuum hose. The slurry is pumped from the hole into large 
tanks located on the work trestle or on a barge, which is either 
recycled for use in the next shaft or transported off site. This 
procedure would be used on all shafts at each pier.
    After shafts are completed, pre-cast concrete, stay-in-place forms 
would be stacked on top of the shafts up to the crossbeam elevation. A 
steel reinforcing cage would be placed inside the concrete forms and 
the columns would be filled with concrete. A pre-cast concrete 
crossbeam or a cast-in-place crossbeam, or some combination of both 
would be constructed on top of the columns. Girders would be fabricated 
off site and would be shipped to the site on barges. The girders would 
then be placed on the piers and falsework towers between piers 2 and 7.
    After completion of the girder placement and casting of diaphragms 
connecting the girders, post-tensioning strands would be placed into 
ducts cast in the girders. The post-tensioning strands will then be 
stressed. The roadway deck would then be formed and cast between piers 
2 and 7.
    Noise levels and characteristics generated by coastal construction 
work related to excavation and drilling are not well studied. Studies 
on construction of offshore oil industry facilities in the Arctic 
provide some insights on the noise levels and characteristics from 
marine dredging. Dredging and drilling noises are broadband with most 
of their energy concentrated in the lower range of the frequency 
spectrum, between 20 1,000 Hz. Nevertheless, these noises are expected 
to be much lower than those from vibratory pile driving at source 
locations.

4. Installation of Girders and Decking

    Girders and decking would be installed using the work trestles, 
falsework towers, and cranes deployed on work barges. The roadway deck 
would be made of concrete and would be poured in place. This work is 
expected to take 3 to 4 months. Noises from this session of work are 
similar to those mentioned above.

5. Reconfiguration of Abutments and Roadway Approaches

    The existing bridge abutments would be removed, along with the 
associated retaining walls. New retaining walls and abutments would be 
constructed. These activities, and associated construction access would 
require the temporary disturbance of 0.75 acre of land, of which 0.15 
acre are vegetated and permanent removal of 0.15 acre of vegetation. 
This work, all in upland areas, includes 2000 cubic yards of fill. Once 
the abutments are complete, the new bridge approach roadways will be 
constructed. Disturbed areas on the east shore of the Port Washington 
Narrows would be restored with a mix of native trees and shrubs 
including marine riparian vegetation and shoreline enhancement. Noises 
from this session of work are similar to those mentioned above 
associated with pier construction.

6. Demolition of Existing Bridge

    The demolition of the existing bridge would occur in phases over a 
period of 18 months. After the central portion of the new bridge is 
constructed, the outermost spans and abutments of the existing bridge 
would be demolished. Once the new abutments and outer spans are 
constructed, the demolition of the remainder of the existing bridge 
will proceed. Conceptual demolition plan sheets are included in 
Appendix D of the WSDOT IHA application.
    The bridge structure above the water line would be cut into 
manageable sections, using conventional concrete and metal cutting 
tools, or a wire saw, and placed on barges for transport to approved 
waste or recycling sites. The portions of the piers below the water 
line would be cut into pieces using a wire saw. All slurry from wire 
cutting operations above the water line would be contained and removed. 
All slurry from wire cutting operations below the water line would be 
dispersed by the current. Piers would be cut off at the ground level 
except for one, Pier 4. Pier 4 was built up to encapsulate original 
creosote treated timbers. Complete removal of the pier is not feasible 
and if it is cut at the ground level, many creosote treated timbers may 
be exposed. To minimize the risk of contamination, Pier 4 would be cut 
two feet above ground level.
    No information is available regarding noises generated from bridge 
structure cutting. However, since the cutting for bridge structures 
would be done above the water line, noise transmitted into the water 
via the structure is not expected to be significant.

7. Removal of Falsework Towers and Work Trestles

    Once the demolition of the existing bridge is complete, the 
falsework towers and work trestles would be removed. Decking and 
girders would be placed on barges for transportation off-site. Piles 
would be removed using vibratory hammers, based on barges. The removal 
of the falsework towers and work trestles is expected to occur over 4 
to 6 months.
    Vibratory extraction is a common method for removing steel piling. 
The pile is unseated from the sediments by engaging the hammer and 
slowly lifting up on the hammer with the aid of the crane. Once 
unseated, the crane would continue to raise the hammer and pull the 
pile from the sediment. When the pile is released from the sediment, 
the vibratory hammer is disengaged and the pile is pulled from the 
water and placed on a barge for transfer upland.

[[Page 13506]]

    Noise levels and characteristics from pile extraction using a 
vibratory hammer are not well studied, however, the intensity of the 
noise is expected to be higher than the intensity of noise from pile 
installation using the same vibratory hammer.
    The Manette Bridge Replacement project is scheduled to begin in 
June 2010 and continue for up to three years. No in-water activities 
will be planned between March 1 and June 14 in water bellow the 
ordinary high water line.

Description of Marine Mammals in the Area of the Specified Activity

    Six marine mammal species/stocks occur in the area where the 
proposed Manette Bridge replacement work is planned. These six species/
stocks are: Pacific harbor seal (Phoca vitulina richardsi), California 
sea lion (Zalophus californianus), Steller sea lion (Eumetopias 
ubatus), transient and Southern Resident killer whales (Orcinus orca), 
and gray whale (Eschrichtius robustus). All these marine mammals have 
been observed in southern Puget Sound during certain periods of the 
year and may occur in Sinclair Inlet, Port Washington Narrows and Dyes 
Inlet, although direct observation in the vicinity of the Manette 
Bridge may not be documented. General information on these marine 
mammal species can be found in Caretta et al. (2007), which is 
available at the following URL: https://www.nmfs.noaa.gov/pr/pdfs/sars/po2008.pdf. Refer to that document for information on these species.
    To further gather information on the occurrence of these marine 
mammal species in the vicinity of the proposed project area, the WSDOT 
contracted ten surveys between the months of July 2006 and January 
2007. This time period was chosen for sampling because it represents 
the time period when most in-water work activities would occur. Two 
pinniped species and zero cetaceans were observed. Thirty four harbor 
seals, one California sea lion and one unidentified pinniped, likely a 
California sea lion, were observed over the six month period. In 
general, cetacean observations are infrequent in the Puget Sound 
(Calambokidis and Baird 1994, Jefferies 2007). During ten surveys for 
marine mammals in Sinclair Inlet and Port Washington Narrows between 
July 2006 and January 2007, no cetaceans were observed. No marine 
mammals were observed during two of the ten surveys. Detailed results 
of the surveys are provided in a final report, which is included in 
Appendix E of the WSDOT IHA application.
    Additional information on these species, particularly in relation 
to their occurrence in the proposed project area, is provided below.

1. Harbor Seal

    Three distinct harbor seal stocks occur along the west coast of the 
continental U.S., the Washington inland waters stock, Oregon/Washington 
coastal stock, and California stock (Caretta et al. 2009). The 
Washington inland waters stock of the Pacific harbor seal is 
distributed in inland waters including Hood Canal, Puget Sound, and the 
Strait of Juan de Fuca out to Cape Flattery (Caretta et al. 2007), and 
is expected to occur in the proposed project area.
    Harbor seal is the most common pinniped and the only marine mammal 
species that breeds in the inland marine waters of Washington 
(Calambokidis and Baird 1994). Pupping and molting typically occurs 
between April and August.
    Individual harbor seals are frequently observed in the Port 
Washington Narrows, Sinclair Inlet and Dyes Inlet. Harbor seals were 
observed during eight of ten surveys between July 2006 and January 
2007. No more than six individuals were observed during any one survey 
period. There are no documented harbor seal haul-out areas within 3 
miles (4.8 km) of the Manette Bridge. One harbor seal haul-out 
estimated at less than 100 animals is documented in Dyes Inlet west of 
the Manette Bridge. These animals must pass through the Port Washington 
Narrows to gain access to Sinclair Inlet and the greater Puget Sound 
basin.
    In 1999, Jefferies et al. (2003) recorded a mean count of 9,550 
harbor seals in Washington's inland marine waters. The estimated 
population for this stock is approximately 14,612 harbor seals with a 
correction factor to account for animals in the water which were missed 
during the aerial surveys (Calambokidis and Baird 1994; Carretta et al. 
2009). From 1991 to 1996, counts of harbor seals in Washington State 
have increased at an annual rate of 10% (Jefferies et al. 1997). Harbor 
seals are not considered to be ``depleted'' under the MMPA or listed as 
``threatened'' or ``endangered'' under the Endangered Species Act 
(ESA).

2. California Sea Lion

    California sea lions occur throughout the Pacific Rim and are 
separated into three subspecies, of which only one occurs in western 
North America (Caretta et al. 2009). The subspecies is further 
separated into three stocks, the United States (US) stock, the Western 
Baja California stock and the Gulf of California stock (Caretta et al. 
2009).
    The U.S. stock of California sea lion is expected to occur in the 
vicinity of the proposed project area. They breed in California and 
southern Oregon between May and July, but not in Washington. Pupping 
occurs on the breeding ground, typically one month prior to mating. Sea 
lions are typically observed in Washington between August and April, 
after they have dispersed from breeding colonies.
    There are no documented California sea lion haul outs within 3 
miles (4.8 km) of the Manette Bridge. Two California sea lion haul-outs 
estimated at less than 10 animals are documented on bouys in Rich 
Passage approximately 4 miles (6.4 km) to the east. Individuals are 
infrequently observed in the Port Washington Narrows, Sinclair Inlet 
and Dyes Inlet. One California sea lion was observed during one of ten 
surveys between July 2006 and January 2007. An unidentified pinniped 
was also recorded during one survey and is believed to be a California 
sea lion, although positive identification was not possible.
    Population estimates are calculated by conducting pup counts. 
Because California sea lions do not breed in Washington, accurate 
estimates of the non-breeding population in Washington do not exist. 
Estimates from the 1980s suggest the population size was just under 
3,000 by the mid-1980s (Bigg 1985; Gearin et al. 1986). In the 1990s, 
the number of sea lions in Washington appears to have either stabilized 
or decreased (Gearin et al. 1988; Calambokidis and Baird 1994). The 
entire population of the US stock of California sea lion is estimated 
to be approximately 238,000 (Carretta et al. 2009). The California sea 
lions are not considered to be ``depleted'' under the MMPA or listed as 
``threatened'' or ``endangered'' under the ESA.

3. Steller Sea Lion

    Steller sea lion occur along the north Pacific Rim with the 
population center in the Gulf of Alaska and the Aleutian Island chain. 
This species is separated into two stocks, the eastern and western 
stocks. The Eastern stock ranges from southeast Alaska south to 
California (Loughlin et al. 1984). The Eastern stock breeds in Alaska, 
British Columbia, Oregon and California, but does not have breeding 
rookeries in Washington. Breeding typically occurs from May to July. 
Pupping occurs within days of returning to the breeding colony.
    Individuals, especially adult males and juveniles, disperse widely 
and travel great distances outside of the

[[Page 13507]]

breeding season, including waters off and within Washington State. 
Individual Steller sea lions typically return to breeding grounds in 
May, although in 2007 and 2008 two to six individual Steller sea lions 
remained all summer near Nisqually (southern Puget Sound near Olympia) 
on the Toliva Shoals and Nisqually buoys. There was also one Steller 
sea lion observed at Point Defiance (near Tacoma, Washington) in July 
2008. Furthermore, reports of Steller sea lions on the North Vashon, 
Manchester and Bainbridge Island bouys increased in winter 2007 - 2008 
and spring 2008 although there are no estimates of individual numbers 
for these reports (WSDOT, 2009). According to Jefferies (2008) there 
are also records from the 1990's of 200 - 300 Steller sea lions using 
Navy floats at the Fox Island Acoustic Range. The majority of Steller 
sea lions are observed in the north Puget Sound and Strait of Juan de 
Fuca, although Steller sea lions are regularly observed at three 
haulout sites in central and southern Puget Sound. The nearest site, 
Shilshole Bay, is on the east side of the Puget Sound, adjacent to the 
city of Seattle approximately 12 miles (19.3 km) from the Manette 
Bridge.
    Population estimates are calculated by conducting pup counts. 
Because Steller sea lions do not breed in Washington, accurate 
estimates of the non-breeding population in Washington do not exist. 
Using the most recent 2005 pup counts from aerial surveys across the 
range of the eastern stock, the total population of the eastern stock 
of Steller sea lion is estimated to be between 46,000 and 58,000 
(Pitcher et al. 2007; Angliss and Allen 2009). The eastern stock of 
Steller sea lion is listed as ``threatened'' under the ESA, and is 
designated as a ``depleted'' stock under the MMPA.

4. Gray Whale

    The North Pacific gray whale stock is divided into two distinct 
stocks: the eastern North Pacific and western North Pacific stocks 
(Rice et al. 1984; Angliss and Allen 2009). The eastern North Pacific 
stock ranges from Alaska, where they summer, to Baja California, where 
they migrate to calve in the winter.
    Gray whales occur frequently off the coast of Washington during 
their southerly migration in November and December, and northern 
migration from March through May (Rugh et al. 2001, Rice et al. 1984). 
Gray whales are observed in Washington inland waters regularly between 
the months of January and September, with peaks between March and May. 
The average tenure within Washington inland waters is 47 days and the 
longest stay was 112 days (Cascadia Research Collective, unpub. 
report). Gray whales are reported in Sinclair Inlet, Port Washington 
Narrows or Dyes Inlet during migration. Between 2001 and 2007, gray 
whale sightings were reported during three of the years (Orca Network 
2007). Reports occurred in April 2002, February, March and May 2005, 
and March and April 2007. The May 2005 observation was a stranding 
mortality at the Kitsap Naval Base in Bremerton (Orca Network 2007).
    Systematic counts of the eastern North Pacific gray whales have 
been conducted by shore-based observers during their southbound 
migration along the central California coast. The most recent abundance 
estimate is based on counts made during the 2001-02 seasons. Based on 
the data, the abundance estimate for this stock of gray whale is 18,178 
individuals (Angliss and Allen 2009). The eastern North Pacific gray 
whale was removed from the ESA-list in 1994, due to steady increases in 
population abundance. Therefore, it is not considered ``endangered'' or 
``threatened'' under the ESA.

5. Killer Whale

    Two distinct forms, or ecotypes, of killer whales ``residents'' and 
``transients'' are found in the greater Puget Sound. These two ecotypes 
are different populations of killer whales that vary in morphology, 
ecology, behavior, and genetics. Both ecotypes of killer whales are not 
known to intermix with one another.
    Resident Killer Whales are noticeably different from both transient 
and offshore forms. The dorsal fin is rounded at the tip and falcate 
(curved and tapering). Resident whales have a variety of saddle patch 
pigmentations with five different patterns recognized. They've been 
sighted from California to Alaska. Resident whales primarily eat fish.
    The ``resident'' population that could occur in the proposed 
project area is the Southern Resident killer whale (SRKW). This 
population contains three pods (or stable family-related groups) J pod, 
K pod, and L pod and is considered a stock under the MMPA. Their range 
during the spring, summer, and fall includes the inland waterways of 
Puget Sound, Strait of Juan de Fuca, and Southern Georgia Strait. Their 
occurrence in the coastal waters off Oregon, Washington, Vancouver 
Island, and more recently off the coast of central California in the 
south and off the Queen Charlotte Islands to the north has been 
documented. Little is known about the winter movements and range of the 
Southern Resident stock. Resident killer whales feed exclusively on 
fish such as salmon (Calambokidis and Baird 1994).
    Southern resident killer whale presence is possible but unlikely in 
the proposed project area. They were last seen in the vicinity of the 
proposed project area in 1997. Nineteen members of L pod (subpod L-25) 
arrived on October 21, 1997 and stayed in Dyes Inlet for 30 days (WSDOT 
2009). A fall chum run has been suggested as the reason for the 
extended stay. The only access to Sinclair Inlet is to the north (Agate 
Passage) or south (Rich Passage) of Bainbridge Island.
    The Southern Resident killer whale population is currently 
estimated at about 86 whales (Carretta et al. 2009), a decline from its 
estimated historical level of about 200 during the mid- to late 1800s. 
Beginning in about 1967, the live-capture fishery for oceanarium 
display removed an estimated 47 whales and caused an immediate decline 
in SRKW numbers. The population fell an estimated 30% to about 67 
whales by 1971. By 2003, the population increased to 83 whales. Due to 
its small population size, NMFS listed this segment of the population 
as endangered under the Endangered Species Act (ESA). This population 
is also listed as depleted under the MMPA.
    Transient killer whales occur throughout the eastern North Pacific, 
primarily in coastal waters. Individual transient killer whales have 
been documented as traveling great distances, reflecting a large home 
range. The dorsal fin of transient whales tends to be more erect 
(straighter at the tip) than those of resident whales. Saddle patch 
pigmentation of transient killer whales is restricted to two patterns. 
Pod structure is small (e.g., fewer than 10 whales) and dynamic in 
nature. Transient killer whales feed exclusively on other marine 
mammals such as dolphins, sea lions, and seals.
    The transient killer whale population that could occur in the 
proposed project area is the West Coast transient stock. It is a trans-
boundary stock, which includes killer whales from British Columbia. The 
presence of this killer whale population in the south Puget Sound is 
considered rare. In 2008, there were only two reports of transient orca 
whales in the south Puget Sound. One of these reports occurred in 
January just east of Maury Island and the other report of transients 
occurred in August in the Tacoma narrows (WSDOT 2009).
    Preliminary analysis of photographic data results in a minimum of 
314 killer whales belonging to the West Coast transient stock (Angliss 
and Allen

[[Page 13508]]

2009). This number is also considered the minimum population estimate 
of the population since no correction factor is available to provide a 
best estimate of the population. At present, reliable data on trends in 
population abundance for the West Coast transient stock of killer 
whales are unavailable (Angliss and Allen 2009). This stock of killer 
whale is not designated as ``depleted'' under the MMPA nor is it listed 
under the ESA.

Potential Effects on Marine Mammals and Their Habitat

    Anticipated impacts resulting from the Manette Bridge Replacement 
project include disturbance from increased human presence and marine 
traffic if marine mammals are in the vicinity of the proposed project 
area, Level B harassment by noises generated from the construction work 
such as pile driving and dredging activities, and the effect of the new 
bridge and stormwater system on water quality.

1. Impacts from Anthropogenic Noise

    Marine mammals exposed to high intensity sound repeatedly or for 
prolonged periods can experience hearing threshold shift (TS), which is 
the loss of hearing sensitivity at certain frequency ranges (Kastak et 
al. 1999; Schlundt et al. 2000; Finneran et al. 2002; 2005). TS can be 
permanent (PTS), in which case the loss of hearing sensitivity is 
unrecoverable, or temporary (TTS), in which case the animal's hearing 
threshold will recover over time (Southall et al. 2007). Since marine 
mammals depend on acoustic cues for vital biological functions, such as 
orientation, communication, finding prey, and avoiding predators, 
marine mammals that suffer from PTS or TTS will have reduced fitness in 
survival and reproduction, either permanently or temporarily. Repeated 
noise exposure that leads to TTS could cause PTS.
    Measured source levels from impact pile driving can be as high as 
214 dB re 1 microPa\2\ 1 m. Although no marine mammals have been shown 
to experience TTS or PTS as a result of being exposed to pile driving 
activities, experiments on a bottlenose dolphin (Tursiops truncates) 
and beluga whale (Delphinapterus leucas) showed that exposure to a 
single watergun impulse at a received level of 207 kPa (or 30 psi) 
peak-to-peak (p-p), which is equivalent to 228 dB re 1 microPa (p-p), 
resulted in a 7 and 6 dB TTS in the beluga whale at 0.4 and 30 kHz, 
respectively. Thresholds returned to within 2 dB of the pre-exposure 
level within 4 minutes of the exposure (Finneran et al. 2002). No TTS 
was observed in the bottlenose dolphin. Although the source level of 
pile driving from one hammer strike is expected to be much lower than 
the single watergun impulse cited here, animals being exposed for a 
prolonged period to repeated hammer strikes could received more noise 
exposure in terms of SEL than from the single watergun impulse 
(estimated at 188 dB re 1 microPa\2\-s) in the aforementioned 
experiment (Finneran et al. 2002).
    However, in order for marine mammals to experience TTS or PTS, the 
animals have to be close enough to be exposed to high intensity noise 
levels for prolonged period of time. Current NMFS standards for 
preventing injury from PTS and TTS is to require shutdown or power-down 
of noise sources when a cetacean species is detected within the 
isopleths corresponding to SPL at received levels equal to or higher 
than 180 dB re 1 microPa (rms), or a pinniped species at 190 dB re 1 
microPa (rms). Based on the best scientific information available, 
these SPLs are far below the threshold that could cause TTS or the 
onset of PTS. Certain mitigation measures proposed by the WSDOT, 
discussed below, can effectively prevent the onset of TS in marine 
mammals, by either reducing the source levels (using an air bubble 
curtain system) and by shut-down and power down procedures for pile 
driving.
    In addition, chronic exposure to excessive, though not high-
intensity, noise could cause masking at particular frequencies for 
marine mammals that utilize sound for vital biological functions. 
Masking can interfere with detection of acoustic signals such as 
communication calls, echolocation sounds, and environmental sounds 
important to marine mammals. Therefore, like TS, marine mammals whose 
acoustical sensors or environment are being masked are also impaired 
from maximizing their performance fitness in survival and reproduction.
    Masking occurs at the frequency band which the animals utilize. 
Therefore, since noise generated from the proposed bridge replacement 
activities, such as pile driving, vessel traffic, and dredging, is 
mostly concentrated at low frequency ranges, it may have less effect on 
high frequency echolocation sounds by killer whales. However, lower 
frequency man-made noises are more likely to affect detection of 
communication calls and other potentially important natural sounds such 
as surf and prey noise. It may also affect communication signals when 
they occur near the noise band and thus reduce the communication space 
of animals (e.g., Clark et al. 2009) and cause increased stress levels 
(e.g., Foote et al. 2004; Holt et al. 2009).
    Unlike TS, masking impacts the species at population, community, or 
even ecosystem levels (instead of individual levels caused by TS). 
Masking affects both senders and receivers of the signals and has long-
term chronic effects on marine mammal species and populations. Recent 
science suggests that low frequency ambient sound levels have increased 
by as much as 20 dB (more than 3 times in terms of SPL) in the world's 
ocean from pre-industrial periods, and most of these increases are from 
distant shipping (Hildebrand 2009). All anthropogenic noise sources, 
such as those from vessels traffic, pile driving, and dredging 
activities, contribute to the elevated ambient noise levels, thus 
intensify masking.
    Nevertheless, the sum of noise from the proposed bridge replacement 
is confined in an area of inland waters that is bounded by landmass, 
therefore, the noise generated is not expected to contribute to 
increased ocean ambient noise.
    Finally, exposure of marine mammals to certain sounds could lead to 
behavioral disturbance (Richardson et al. 1995), such as: changing 
durations of surfacing and dives, number of blows per surfacing, or 
moving direction and/or speed; reduced/increased vocal activities, 
changing/cessation of certain behavioral activities (such as 
socializing or feeding); visible startle response or aggressive 
behavior (such as tail/fluke slapping or jaw clapping), avoidance of 
areas where noise sources are located, and/or flight responses (e.g., 
pinnipeds flushing into water from haulouts or rookeries).
    The biological significance of many of these behavioral 
disturbances is difficult to predict, especially if the detected 
disturbances appear minor. However, the consequences of behavioral 
modification could be expected to be biologically significant if the 
change affects growth, survival, and reproduction. Some of these 
significant behavioral modifications include:
     Drastic change in diving/surfacing patterns (such as those 
thought to be causing beaked whale stranding due to exposure to 
military mid-frequency tactical sonar);
     Habitat abandonment due to loss of desirable acoustic 
environment; and
     Cease feeding or social interaction.
    For example, at the Guerreo Negro Lagoon in Baja California, 
Mexico, which is one of the important breeding grounds for Pacific gray 
whales, shipping and dredging associated with a salt works may have 
induced gray

[[Page 13509]]

whales to abandon the area through most of the 1960s (Bryant et al. 
1984). After these activities stopped, the lagoon was reoccupied, first 
by single whales and later by cow-calf pairs.
    The onset of behavioral disturbance from anthropogenic noise 
depends on both external factors (characteristics of noise sources and 
their paths) and the receiving animals (hearing, motivation, 
experience, demography) and is also difficult to predict (Southall et 
al. 2007).
    The proposed project area is not believed to be a prime habitat for 
marine mammals, nor is it considered an area frequented by marine 
mammals. Therefore, behavioral disturbances that could result from 
anthropogenic construction noise associated with bridge replacement are 
expected to affect only a small number of marine mammals on an 
infrequent basis.
    Currently NMFS uses 160 dB re 1 microPa at received level for 
impulse noises (such as impact pile driving) as the onset of marine 
mammal behavioral harassment, and 120 dB re 1 microPa for continued 
noises (vibratory pile driving and dredging).
    As far as airborne noise is concerned, as mentioned before, the 
nearest pinniped haulout (harbor seal) is in Dyes Inlet, which is 
approximately 3 miles (4.8 km) west of the proposed project area. NMFS 
does not expect that airborne noise from pile driving would reach 
harassment levels at this distance.

2. Impacts from Presence of Human Activities

    In addition to noise induced disturbances and harassment, the 
increased human presence and vessel traffic associated with the bridge 
replacement construction is also expected to have adverse impacts to 
marine mammals in the vicinity of the proposed project.
    Some of the expected impacts could result from work trestles and 
barge anchoring. The construction and demolition work trestles would 
cover up to 55,900 square feet (5,193 m\2\) of the Port Washington 
Narrows throughout the construction period, a duration of approximately 
three years, although neither trestle would be in place for that entire 
period. The size of these trestles has been reduced to the greatest 
extent practicable according to WSDOT. The demolition trestle would be 
installed during the in-water work window immediately prior to 
initiation of bridge demolition activities occurring from this trestle 
and both trestles would be removed as soon as practicable following the 
completion of construction and demolition activities. Barge anchoring 
would occur adjacent to the construction and demolition work trestles 
creating a passage the width of the shipping channel between the Port 
Washington Narrows and Sinclair Inlet. Killer whales, if they happen to 
be present in the vicinity of the area, could become confined by 
psychological barriers such as nets or low walls that they can 
physically cross, but for unknown reasons do not. Such was the case in 
1994 in Barnes Lake near Ketchikan, Alaska, when 10 killer whales 
entered following salmon but then refused to leave until human 
intervention chased them out of the lake (Anonymous 1995; Bain 1995). 
In 1997, 19 members of the L pod of the Southern Resident killer whales 
entered Dyes Inlet near Bremerton, Washington, which is approximately 3 
miles (4.8 km) west of the proposed project area and is surrounded by 
urban and residential development, and stayed there for nearly 30 days 
(Wiles 2004; NMFS 2008). The long length of residence of killer whales 
in this area was highly unusual and the reason is unclear, but may have 
been related to food abundance since it was coincidence to a strong run 
of chum salmon into Chico Creek between late October and November, or a 
reluctance by the whales to depart the inlet because of the physical 
presence of a bridge crossing the Port Washington Narrows and 
associated road noise (Wiles 2004; NMFS 2008). The work trestles and 
barges may present a similar situation that would discourage or prevent 
killer whales from exiting Dyes Inlet or Port Washington Narrows and 
returning to more open water if the whales happen to enter the inlet. 
However, as mentioned before, the occurrence of killer whales in the 
vicinity of proposed project area is not frequent.

3. Impacts from Water Quality

    Marine mammals are especially vulnerable to contaminants because 
their apex trophic levels in the ecosystem promote bioaccumulation of 
contaminants. Water quality conditions will generally improve as a 
result of the construction of stormwater treatment facilities 
associated with the project. Currently, stormwater from the existing 
roadway and bridge is discharged, untreated, into the Port Washington 
Narrows. The WSDOT states that post project, all stormwater leaving the 
bridge would receive treatment by the city of Bremerton. Therefore, the 
impact from water quality is expected to be reduced as the result of 
the proposed bridge replacement project.

Proposed Mitigation Measures

    In order to issue an incidental take authorization under Section 
101(a)(5)(D) of the MMPA, NMFS must set forth the permissible methods 
of taking pursuant to such activity, and other means of effecting the 
least practicable adverse impact on such species or stock and its 
habitat, paying particular attention to rookeries, mating grounds, and 
areas of similar significance, and on the availability of such species 
or stock for taking for certain subsistence uses.
    For the proposed Manette Bridge replacement project, the WSDOT 
worked with NMFS and proposed the following mitigation measures to 
minimize the potential impacts to marine mammals in the project 
vicinity as a result of the construction activities.

1. Overall Construction Activities

    The WSDOT states that all its construction is performed in 
accordance with the current WSDOT Standard Specifications for Road, 
Bridge, and Municipal Construction. Special Provisions contained in 
contracts are used in conjunction with, and supersede, any conflicting 
provisions of the Standard Specifications.
    WSDOT activities are subject to state and local permit conditions. 
WSDOT states that it uses the best guidance available (e.g., best 
management practices and conservation measures) to accomplish the 
necessary work while avoiding and minimizing environmental impacts to 
the greatest extent possible.
    The WSDOT contractor is expected to be responsible for the 
preparation of a Spill Prevention, Control, and Countermeasures plan to 
be used for the duration of the project. The plan would be submitted to 
the WSDOT Project Engineer prior to the commencement of any 
construction activities. A copy of the plan with any updates will be 
maintained at the work site by the contractor. A detailed discussion of 
the plan is provided in the WSDOT's IHA application.

2. Equipment Noise Standards

    To mitigate noise levels and, therefore, impacts to marine mammals, 
all the construction equipment would comply with applicable equipment 
noise standards of the U.S. Environmental Protection Agency, and all 
construction equipment will have noise control devices no less 
effective than those provided on the original equipment.

3. Timing Windows

    Timing restrictions are used to avoid construction activities that 
generate relatively intense underwater noises

[[Page 13510]]

(i.e., pile driving, dredging, and dynamic positioning) when ESA-listed 
species are most likely to be present. If an ESA-listed marine mammal 
species is detected in the vicinity of the project area, pile driving 
and dredging operations will be halted and stationing construction 
vessels will turn off dynamic positioning systems. WSDOT states that it 
will comply with all in-water timing restrictions as determined through 
the MMPA take authorization. Pile driving activities would only be 
conducted during daylight hours. If the safety zone (see below) is 
obscured by fog or poor lighting conditions, impact pile driving will 
not be initiated until the entire safety zone is visible. In addition, 
no in-water work would be conducted between March 1 and June 14 in 
water below the ordinary high water line.

4. Establishment of Zones of Safety and Influence

    For impact pile driving, the safety zones are defined as the areas 
where received SPLs from noise source exceed 180 dB re 1 microPa (rms) 
for cetaceans or 190 dB re 1 microPa (rms) for pinnipeds. Repeated and 
prolonged exposure to SPLs above these values may cause TTS to 
cetaceans and pinnipeds, respectively. The radii of the safety zones 
would be determined through empirical measurements of acoustic data. 
Prior to acquiring acoustic data, the safety zones shall be established 
based on the worst-case scenario measured from impact pile driving of 
36-inch (0.91 m) steel pile conducted elsewhere, such as the Anacortes 
or Mukiteo ferry terminals. Acoustic measurements indicate that source 
levels are approximately 201 dB re 1 microPa (rms) at 10 m for both 
pile driving activities for Anacortes and Mukiteo ferry terminal 
constructions when the 36-inch (0.91 m) piles were hammered in 
(Laughlin 2007; Sexton 2007). Approximation of the received levels of 
180 and 190 dB re 1 microPa (rms) by using an acoustic propagation 
spreading model between spherical and cylindrical propagation,
    TL = 15log(RRL/RSL),
    where TL is the transmission loss (in dB), RRL is the distance at 
received levels (either 180 or 190 dB), and RSL is the 
distance (10 m) at source level (201 dB). The results show that the 
distances for received levels 180 and 190 dB re 1 microPa (rms) are 
approximately 251 m and 54 m, respectively. NMFS expects that the 
modeled safety zones are reasonably conservative as the propagation 
model does not take into consideration other transmission loss factors 
such as sound absorption in the water column.
    Once impact pile driving begins, NMFS requires that the contractor 
adjust the size of the safety zones based on actual measurements of 
SPLs at various distances to determine the most conservative (the 
largest) safety zones at which the received levels are 180 and 190 dB 
re 1 microPa (rms).
    Since the source levels for vibratory pile driving are expected to 
be under 180 dB re 1 microPa (rms) at 10 m, no safety zones would be 
established for vibratory pile driving.
    In addition, WSDOT and its contractor shall establish zones of 
influence (ZOIs) at received levels of 160 and 120 dB re 1 microPa 
(rms) for impulse noise (noise from impact pile driving) and non-
impulse noise (such as noise from vibratory pile driving and dynamic 
positioning system), respectively. These SPLs are expected to cause 
Level B behavioral harassment to marine mammals. The model based 
approximation for the distance at 160 dB received level is 5,412 m from 
pile driving based on the most conservative measurements from the 
Anacortes or Mukiteo ferry terminal construction (201 dB re 1 microPa 
(rms) at 10 m; Laughlin 2007; Sexton 2007), using the same spreading 
model discussed above. Once impact pile driving starts, the contractor 
shall conduct empirical acoustic measurements to determine the most 
conservative distance (the largest distance from the pile) where the 
received levels begin to fall below 160 dB re 1 microPa (rms).
    As far as non-pulse noises are concerned, for which the Level B 
behavioral harassment is set at a received level of 120 dB re 1 
microPa, no simple modeling is available to approximate the distance 
(though direct calculation using the spreading model puts the 120 dB 
received level at 100 km, this simple approximation no longer works at 
this long distance due to range-dependent propagation involving complex 
sound propagation behavior that cannot be ignored). NMFS uses the 
empirical underwater acoustic measurements from vibratory pile driving 
of 42 48-inch (1.06 1.22 m) diameter piles at the San Francisco-Oakland 
Bay Bridge construction as a model and expects that the distance at a 
received level of 120 dB is less than 1,900 m from the pile (CALTRANS 
2009). Likewise, WSDOT and its contractor shall conduct empirical 
acoustic measurements to determine the actual distance of 120 dB re 1 
microPa (rms) from the pile.
    All safety and influence zones shall be monitored for marine 
mammals prior to and during construction activities. Please refer to 
the Monitoring and Reporting Measures section for a detailed 
description of monitoring measures.

5. Shutdown Measures

    To prevent marine mammals from exposure to intense sounds that 
could potentially lead to TTS (i.e., received levels above 180 dB and 
190 dB re 1 microPa (rms) for cetaceans and pinnipeds, respectively), 
no impact pile driving shall be initiated when marine mammals are 
detected within these safety zones. In addition, during impact driving, 
when a marine mammal is detected within the respective safety zones or 
is about to enter the safety zones, impact pile driving shall be halted 
and shall not be resumed until the animal is seen to leave the safety 
zone on its own, or 30 minutes has elapsed until the animal is last 
seen.
    WSDOT also agrees that pile driving and dredging activities would 
be suspended when ESA-listed marine mammals (Steller sea lion and 
killer whale) are detected within the zone of behavioral harassment 
(160 dB re 1 microPa for impulse sources and 120 dB re 1 microPa for 
non-impulse sources) and that all vessels' dynamic positioning systems 
would be turned off. Therefore, no take of ESA-listed marine mammal 
species or stocks is expected.

6. ``Soft Start'' Impact Pile Driving or Ramp-up

    Although marine mammals will be protected from Level A harassment 
by establishment of an air-bubble curtain during impact pile driving 
and marine mammal observers monitoring a safety zone, monitoring may 
not be 100 percent effective at all times in locating marine mammals. 
Therefore, WSDOT proposes to use a 'soft-start' technique at the 
beginning of each day's in-water pile driving activities or if pile 
driving has ceased for more than one hour to allow any marine mammal 
that may be in the immediate area to leave before pile driving reaches 
full energy.
    For vibratory pile driving, the soft start requires contractors to 
initiate noise from vibratory hammers for 15 seconds at reduced energy 
followed by a one minute waiting period. The procedure will be repeated 
two additional times. If an impact hammer is used on a pile greater 
than 10 inches in diameter, contractors will be required to provide an 
initial set of three strikes from the impact hammer at 40 percent 
energy, followed by a one minute waiting period, then two subsequent 3-
strike sets. This should expose fewer animals to loud sounds both 
underwater and above water noise. This would also ensure that, although 
not expected, any

[[Page 13511]]

pinnipeds and cetaceans that are missed during safety zone monitoring 
will not be injured.

7. Sound Attenuation Measures

    Specific to pile driving, the following mitigation measures are 
proposed by WSDOT to reduce impacts to marine mammals to the greatest 
extent practicable.
    All steel piles would be installed using a vibratory hammer until 
an impact hammer is needed for bearing or if a pile encounters 
consolidated material. If vibratory installation is not possible due to 
the substrate, an impact pile driver would be used. An air bubble 
curtain(s) will be employed during impact installatio