[Federal Register Volume 87, Number 211 (Wednesday, November 2, 2022)]
[Notices]
[Pages 66133-66161]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2022-23775]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

[RTID 0648-XC247]


Takes of Marine Mammals Incidental to Specified Activities; 
Taking Marine Mammals Incidental to Relocation of National Oceanic and 
Atmospheric Administration Research Vessels at Naval Station Newport, 
Rhode Island

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

ACTION: Notice; proposed incidental harassment authorization; request 
for comments on proposed authorization and possible renewal.

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SUMMARY: NMFS has received a request from the U.S. Navy on behalf of 
NOAA Office of Marine and Aviation Operations (OMAO) for authorization 
to take marine mammals incidental to construction activities associated 
with the relocation of NOAA research vessels at Naval Station Newport 
in Rhode Island. Pursuant to the Marine Mammal Protection Act (MMPA), 
NMFS is requesting comments on its proposal to issue an incidental 
harassment authorization (IHA) to incidentally take marine mammals 
during the specified activities. NMFS is also requesting comments on a 
possible one-time, 1-year renewal that could be issued under certain 
circumstances and if all requirements are met, as described in Request 
for Public Comments at the end of this notice. NMFS will consider 
public comments prior to making any final decision on the issuance of 
the requested MMPA authorization and agency responses will be 
summarized in the final notice of our decision.

DATES: Comments and information must be received no later than December 
2, 2022.

ADDRESSES: Comments should be addressed to Jolie Harrison, Chief, 
Permits and Conservation Division, Office of Protected Resources, 
National Marine Fisheries Service and should be submitted via email to 
[email protected].
    Instructions: NMFS is not responsible for comments sent by any 
other method, to any other address or individual, or received after the 
end of the comment period. Comments, including all attachments, must 
not exceed a 25-megabyte file size. All comments received are a part of 
the public record and would generally be posted online at 
www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act 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.

FOR FURTHER INFORMATION CONTACT: Jessica Taylor, Office of Protected 
Resources, NMFS, (301) 427-8401. Electronic copies of the application 
and supporting documents, as well as a list of the references cited in 
this document, may be obtained online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities. In case of problems 
accessing these documents, please call the contact listed above.

SUPPLEMENTARY INFORMATION:

Background

    The MMPA prohibits the ``take'' of marine mammals, with certain 
exceptions. Sections 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361 
et seq.) direct the Secretary of Commerce (as delegated to NMFS) 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 proposed or, if the taking is limited to harassment, a notice of a 
proposed incidental harassment 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) and will not have an unmitigable adverse impact on the 
availability of the species or stock(s) for taking for subsistence uses 
(where relevant). Further, NMFS must prescribe the permissible methods 
of taking and other ``means of effecting the least practicable adverse 
impact'' on the affected species or stocks and their habitat, paying 
particular attention to rookeries, mating grounds, and areas of similar 
significance, and on the availability of the species or stocks for 
taking for certain subsistence uses (referred to in shorthand as 
``mitigation''); and requirements pertaining to the mitigation, 
monitoring and reporting of the takings are set forth. The definitions 
of all applicable MMPA statutory terms cited above are included in the 
relevant sections below.

[[Page 66134]]

National Environmental Policy Act

    To comply with the National Environmental Policy Act of 1969 (NEPA; 
42 U.S.C. 4321 et seq.) and NOAA Administrative Order (NAO) 216-6A, 
NMFS must review our proposed action (i.e., the issuance of an IHA) 
with respect to potential impacts on the human environment.
    This action is consistent with categories of activities identified 
in Categorical Exclusion B4 (IHAs with no anticipated serious injury or 
mortality) of the Companion Manual for NOAA Administrative Order 216-
6A, which do not individually or cumulatively have the potential for 
significant impacts on the quality of the human environment and for 
which we have not identified any extraordinary circumstances that would 
preclude this categorical exclusion. Accordingly, NMFS has 
preliminarily determined that the issuance of the proposed IHA 
qualifies to be categorically excluded from further NEPA review. We 
will review all comments submitted in response to this notice prior to 
concluding our NEPA process or making a final decision on the IHA 
request.

Summary of Request

    On May 6, 2022, NMFS received a request from the U.S. Navy on 
behalf of OMAO for an IHA to take marine mammals incidental to 
construction activities associated with the relocation of NOAA research 
vessels to the Naval Station Newport in Rhode Island. NMFS reviewed the 
Navy's application and the Navy provided a revised application on July 
14, 2022. The application was deemed adequate and complete on October 
5, 2022. OMAO's request is for take of 7 species of marine mammals, by 
Level B harassment and, for a subset of these species, Level A 
harassment. Neither OMAO nor NMFS expect serious injury or mortality to 
result from this activity and, therefore, an IHA is appropriate. OMAO 
plans to commence in-water construction activities on February 1, 2024 
yet has requested the IHA in advance due to OMAO's NEPA requirements.

Description of Proposed Activity

Overview

    OMAO proposes to establish adequate pier, shore side, and support 
facilities for four NOAA research vessels in Coddington Cove at Naval 
Station (NAVSTA) Newport in Newport, Rhode Island. As part of the 
proposed activity, a new pier, trestle, small boat floating dock, and 
bulkhead would be constructed in Coddington Cove in order to meet NOAA 
docking/berthing requirements for these four vessels. These 
construction activities would involve the use of impact and vibratory 
pile driving, vibratory pile extraction, rotary drilling, and down-the-
hole (DTH) mono-hammer excavation events, which have the potential to 
take marine mammals, by Level A and Level B harassment. The project 
would also include shore side administrative, warehouse, and other 
support facilities.
    Currently two of the four Rhode Island NOAA research vessels are 
located at Pier 2 at NAVSTA Newport; however, Pier 2 does not provide 
adequate docking and berthing for these vessels to meet NOAA 
requirements. The two other NOAA Atlantic Fleet vessels are located in 
New Hampshire, Virginia, South Carolina, or Mississippi. As many of the 
NOAA research cruises are conducted in the northeast, relocating four 
vessels to the project area provides logistical advantages and 
operational efficiencies.
    Coddington Cove, which opens to Narragansett Bay, covers an area of 
approximately 395 acres (1.6 square kilometers) and is located near the 
southeast corner of NAVSTA Newport. Construction activities would last 
for approximately 1 year from February 1, 2024 to January 31, 2025 of 
which in-water work would take place over 343 non-consecutive days.

Dates and Duration

    In-water construction activities are estimated to occur over 343 
non-consecutive days from February 1, 2024 to January 31, 2025. OMAO 
anticipates that all work would be limited to daylight hours. Specific 
construction activities may occur concurrently over a period of 
approximately 138 days. Table 1 provides a summary of proposed 
scenarios in which equipment may be used concurrently.

                                Table 1--Summary of Multiple Equipment Scenarios
----------------------------------------------------------------------------------------------------------------
              Structure                           Activity                      Equipment and quantity
----------------------------------------------------------------------------------------------------------------
Bulkhead.............................  Template installation (16-     Vibratory Hammer (2).
                                        inch steel) and steel pipe    Vibratory Hammer (1), Impact Hammer (1).
                                        pile installation (18-inch).
                                                                      Vibratory Hammer (2), DTH Mono-hammer (1).
----------------------------------------------------------------------------------------------------------------
Bulkhead and Trestle.................  Template extraction from       Vibratory Hammer (3).
                                        Bulkhead (16-inch steel),     Vibratory Hammer (1), Impact Hammer (1),
                                        Install sheet piles Bulkhead   Rotary Drill (1).
                                        (Z26-700), Install steel
                                        pipe piles at Trestle (18-
                                        inch).
                                                                      Vibratory Hammer (2), Impact Hammer (1),
                                                                       Rotary Drill (1).
----------------------------------------------------------------------------------------------------------------
Pier.................................  Template Install (16-inch      Vibratory Hammer (2).
                                        steel) and Install steel      Vibratory Hammer (1), Impact Hammer (1)
                                        pipe piles (30-inch) at Pier.
                                                                      Vibratory Hammer (1), Impact Hammer (1),
                                                                       Rotary Drill (1).
----------------------------------------------------------------------------------------------------------------
Pier fender piles, gangway, and        Install pipe piles (16-inch)   Vibratory Hammer (2)
 floating dock.                         at Pier and install steel     Vibratory Hammer (1), Impact Hammer (1).
                                        pipe piles at Small Boat
                                        Floating Dock (18-Inch).

[[Page 66135]]

 
                                       Template Extraction from Pier  Vibratory Hammer (2), Impact Hammer (1).
                                        (16-inch steel) and install   Vibratory Hammer (1), Impact Hammer (1).
                                        shafts (36-inch) at Small
                                        Boat Floating Dock.
                                                                      Vibratory (2), DTH Mono-hammer (1).
----------------------------------------------------------------------------------------------------------------

Specific Geographic Region

    NAVSTA Newport encompasses 1,399 acres (5.66 (square kilometers) 
km\2\) extending 6-7 miles (9.7-11.3 kilometers (km)) along the western 
shore of Aquidneck Island in the towns of Portsmouth and Middletown, 
Rhode Island and the city of Newport, Rhode Island. The base footprint 
also includes the northern third of Gould Island in the town of 
Jamestown, Rhode Island. The base is located in the southern part of 
the state where Narragansett Bay adjoins the Atlantic Ocean. Figure 1 
shows the site of where the proposed action would occur in Coddington 
Cove.
    Coddington Cove covers an area of approximately 395 acres (1.6 
km\2\) and is partially protected by Coddington Point to the south and 
a breakwater to the north. The northwest section of the cove opens to 
Narragansett Bay. Water depths in the proposed project area of 
Coddington Cove are less than 34 ft (10.4 m) mean lower low water. The 
proposed project area experiences semi-diurnal tides, an average water 
temperature of 36-68 [deg]F (2.2-20 [deg]C), and salinity of 31 parts 
per thousand. Narragansett Bay is approximately 22 nautical miles (nm) 
(40 km) long and 7 nm (16 km) wide. Narragansett Bay's most prominent 
bathymetric feature is a submarine valley that runs between Conanicut 
and Aquidneck Islands to Rhode Island Sound, and defines the East 
Passage of Narragansett Bay. The shipping channel in the East Passage 
serves as the primary shipping channel for the rest of Narragansett Bay 
and is generally 100 ft (30.5 m) deep. The shipping channel from the 
lower East Passage splits just south of Gould Island with the western 
shipping channel heading to Quonset Point and the eastern shipping 
channel heading to Providence and Fall River (Navy, 2008). Vessel noise 
from commercial shipping and recreational activities contribute to the 
ambient underwater soundscape in the proposed project area. Based upon 
underwater noise data collected at the Naval Undersea Warfare Center 
(NUWC) and the shallow depth of nearshore water, the ambient underwater 
noise in the proposed project area is expected to be approximately 120 
dB RMS.
BILLING CODE 3510-22-P

[[Page 66136]]

[GRAPHIC] [TIFF OMITTED] TN02NO22.000

BILLING CODE 3510-22-C
Figure 1. Proposed NAVSTA Project Area

Detailed Description of the Specified Activity

    The proposed activity would establish adequate pier, shore side, 
and support facilities to support the relocation of four NOAA Atlantic 
Fleet research vessels at NAVSTA Newport, RI. This includes the 
construction of a new pier, trestle, small boat floating dock, 
bulkhead, and shore side facilities in Coddington Cove for which the 
in-water schedule is shown in Table 2. Upland construction at the Pier 
landing and parking facilities near Building 11 (Figure 1) would not 
involve any in-water work and is not expected to result in any takes of 
marine mammals; these activities are therefore not further discussed.

                                                        Table 2--Proposed In-Water Work Schedule
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                      Minutes to
                                                                                                                        drive/     Number of
                                 Construction      Pile type and                     Method of pile       Daily        extract/     impact       Total
           Facility                 period         diameter (in)   Number of piles      driving/     production rate    drill a    strikes/   production
                                                                                       extraction                       single       pile      days \1\
                                                                                                                         pile
--------------------------------------------------------------------------------------------------------------------------------------------------------
Abandoned guide piles along    February 2024...  12'' steel......  3..............  Vibratory        3 piles/day....          30         N/A           1
 bulkhead.                                                                           extraction.
Floating dock demolition.....  February 2024...  12'' timber.....  4..............  Vibratory        4 piles/day....          30         N/A           1
                                                                                     extraction.
Bulkhead Construction........  February-April    18'' steel......  115............  Vibratory/       8 piles/day....          30       1,000          15
                                2024.                                                impact.

[[Page 66137]]

 
                                                                   12.............  DTH Mono-hammer  1 hole/day.....         300          13          12
                                                                                     \2\ \3\.
                                                 Steel sheet pile  230 (115 pairs)  Vibratory......  8 pairs/day....          30         N/A          15
                                                  Z26-700, 18''
                                                  deep.
                                                 16 template       60 (4x 15        Vibratory        4 piles/day....          30         N/A          30
                                                  steel pile.       moves).          installation/
                                                                                     extraction.
Trestle......................  April-June 2024   18'' steel pipe   36.............  Vibratory/       2 piles/day....          30       1,500          18
                                *.                pile.                              impact.
bents 1-18...................                                      4..............  Rotary drilling  1 hole/day.....         300         N/A           4
                                                                                     \4\.
                                                 16'' template     72 (4x 18        Vibratory        4 piles/day....          30         N/A          36
                                                  steel pipe pile.  moves).          installation/
                                                                                     extraction.
Trestle......................  June 2024.......  30'' steel pipe   2..............  Vibratory/       2 piles/day....          45       2,000           1
                                                  pile.                              impact.
bent 19......................                    16'' template     4 (4x 1 moves).  Vibratory        4 piles/day....          30         N/A           2
                                                  steel pipe pile.                   installation/
                                                                                     extraction.
Pier.........................  June-December     30'' steel pipe   120............  Vibratory/       4 piles/day....          45       2,000          30
                                2024 **.          pile.                              impact.
                                                                   12.............  Rotary drilling  1 hole/day.....         300         N/A          12
                                                                                     \4\.
                                                 16'' template     120 (4x 30       Vibratory        4 piles/day....          30         N/A          60
                                                  steel pipe pile.  moves).          installation/
                                                                                     extraction.
Fender Piles.................  September 2024-   16'' steel pipe   201............  Vibratory......  4 piles/day....          20         N/A          50
                                January 2025 **.  pile.
                                                 16'' template     96 (4x 24        Vibratory        4 piles/day....          30         N/A          48
                                                  steel pipe pile.  moves).          installation/
                                                                                     extraction.
Gangway support piles for      January 2025 **.  18'' steel pipe   4..............  Vibratory/       2 piles/day....          30       1,000           2
 small boat floating dock.                        piles.                             impact.
Small floating dock..........  January 2025 **.  36'' steel        2..............  Vibratory/       1 pile/day.....          60       1,000           2
                                                  casing shaft                       impact.
                                                  with rock
                                                  socket (guide
                                                  pile).
                                                                   2..............  DTH Mono-hammer  1 hole/day.....         300  13 strikes/          2
                                                                                     \2\ \3\ \5\.                                     second
                                                 16'' template     4 (4x 1 moves).  Vibratory        4 piles/day....          30         N/A           2
                                                  steel pipe pile.                   installation/
                                                                                     extraction.
--------------------------------------------------------------------------------------------------------------------------------------------------------
* Pile installation at Bulkhead and Trestle may be concurrent.
** Pile installation of Fender piles, Gangway, and Floating Dock may be concurrent.
\1\ Total production days for template piles includes the time to install and the time to extract the piles.
\2\ ``Down-the-hole'' (DTH) mono-hammer excavation may be used to clear boulders and other hard driving conditions for pipe piling at the bulkhead. DTH
  mono-hammer would only be used when obstructions or refusal (hard driving) occurs that prevents the pile from being advanced to the required tip
  elevation using vibratory/impact driving. The DTH mono-hammer is placed inside of the steel pipe pile and operates at the bottom of the hole to clear
  through rock obstructions, hammer does not ``drive'' the pile but rather cleans the pile and removes obstructions such that the piles may be installed
  to ``minimum'' tip elevation.
\3\ DTH mono-hammer uses both impulsive (strikes/second) and continuous methods (minutes).
\4\ Rotary drilling may be used to clear boulders/obstructions for trestle and pier. Core barrel would be lowered through the pile and advanced using
  rotary methods to clear the obstruction. After the obstruction is cleared, the piling would be advanced to the required tip elevation using impact
  driving methods.
\5\ DTH mono-hammer would be used to create a rock socket at each of the 36-inch shafts for the floating dock.

    Pier and Trestle: A new pile supported concrete pier would be 
constructed approximately 450 ft (137.1 m) north of the existing T-pier 
in Coddington Cover (Figure 1). The new pier would be approximately 62 
ft (18.9 m) wide and and 587 ft (178.9 m) long, encompassing an area of 
36,400 square ft (ft\2\, 3,381.6 m\2\). Structural support piles for 
the new pier would consist of 120 30'' steel pipe piles. These piles 
would be driven by vibratory and impact hammers to a depth required to 
achieve bearing capacity. A rotary drill may be used to clear any 
obstructions, such as glacial boulders. Fender piles would be installed 
and consist of 201 16'' diameter steel pipe piles.
    In order to access the pier, a 28 ft (8.5 m) wide by 525 ft (160 m) 
long pile-supported trestle would be constructed. The trestle would 
cover an area of approximately 14,200 ft\2\ (1,319.2 m\2\) over the 
water. The entrance to the trestle would be located upland and span 
over two existing bulkheads, a sheet pile bulkhead, and a new bulkhead 
connected to the pier. Structural support piles for the trestle 
concrete deck would include 36 18'' steel pipe piles and 2 30'' steel 
pipe piles. The piles would be driven by impact and vibratory hammers 
to depths required to achieve bearing capacity. If construction crews 
encounter obstructions, such as glacial boulders, a rotary drill may be 
used.
    Trestle and pier piles would be installed using a template that 
would be secured by 4 16'' steel pipe piles. Once the pier or trestle 
piles are installed in the template, the template would be removed and 
relocated to the next section of the pier/trestle construction. The 
template piles would be installed and removed by vibratory installation 
and extraction. Use of the template would require the driving and 
removal of the template piles approximately 19 times for the trestle 
and 30 times for the pier, for a total of 196 installation/extraction 
moves of the pipe piles.
    Small Boat Floating Dock: A small boat floating dock would be 
constructed northwest of the pier and trestle structure. The dock would 
be approximately 20 ft (6.1 m) wide by 66 ft (20.1 m) long, and provide 
berthing on two sides. The floating system would consist of a single 
heavy duty 20 ft (6.1 m) by 66 ft (20.1 m) concrete float of 
approximately 1,300 ft\2\ (120.8 m\2\) and two 5.5 ft (1.7 m) wide by 
80 ft (24.3 m) long gangway segments of approximately 440 ft\2\ (40.9 
m\2\) each. The gangway would be supported by 4 18'' steel pipe piles. 
These piles would be driven by vibratory installation followed by 
impact installation to achieve bearing capacity. Two 36'' steel pipe 
guide piles would provide lateral support to the floating dock. The 
guide piles would be rock socketed into the bedrock. Shafts would be 
installed using vibratory and impact driving methods, then set into 
rock socket anchors and filled with concrete. DTH excavation using a 
mono-hammer would be used to

[[Page 66138]]

create the rock sockets. Additionally, an abandoned dock currently 
exists at the proposed site of the floating dock. Demolition of the 
abandoned dock involving the vibratory extraction of 3 12'' steel pipe 
piles and 4 12'' timber piles would take place before the small boat 
floating dock would be installed.
    Bulkhead: In order to reinforce and stabilize an existing 
deteriorating bulkhead, a new bulkhead of approximately 728 ft (221.9 
m) in length would be constructed near the proposed new pier location. 
A combination of approximately 115 18'' steel pipe piles and 230 steel 
Z-shaped sheet piles (55'' long and 8'' deep) would be installed along 
the face of the existing bulkhead using vibratory and impact driving. 
If obstructions, such as solid bedrock, boulders, or debris are 
encountered, pile installation may require the use of DTH mono-hammer 
excavation to break up rock or moving the obstruction aside using 
mechanical means. Piles would be installed using a template that would 
be secured by 4 16'' steel pipe piles. The use of the template would 
require the vibratory driving and extraction of the 4 template piles 
approximately 15 times for a total of 60 installation/extraction moves 
of the pipe template piles.
    Pile installation and removal would occur using barge-mounted 
cranes and land-based cranes equipped with vibratory and impact 
hammers. Piles would initially be installed using vibratory methods, 
then finished with impact hammers as necessary. Impact hammers would 
also be used where obstructions or sediment conditions do not permit 
the efficient use of vibratory hammers. Rotary drilling may be used to 
clear obstructions during pile driving. DTH mono-hammer excavation 
combines the use of rotary drilling and percussive hammering to 
fracture rock. This method may also be used to clear obstructions in 
addition to set piles in rock sockets. Piles would be driven using a 
vibratory pile driver whenever possible in order to reduce impacts.
    Proposed mitigation, monitoring, and reporting measures are 
described in detail later in this document (please see Proposed 
Mitigation and Proposed Monitoring and Reporting).

Description of Marine Mammals in the Area of Specified Activities

    Sections 3 and 4 of the application summarize available information 
regarding status and trends, distribution and habitat preferences, and 
behavior and life history of the potentially affected species. NMFS 
fully considered all of this information, and we refer the reader to 
these descriptions, incorporated here by reference, instead of 
reprinting the information. Additional information regarding population 
trends and threats may be found in NMFS' Stock Assessment Reports 
(SARs; www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments) and more general information about these 
species (e.g., physical and behavioral descriptions) may be found on 
NMFS' website (https://www.fisheries.noaa.gov/find-species).
    Table 3 lists all species or stocks for which take is expected and 
proposed to be authorized for these activities, and summarizes 
information related to the population or stock, including regulatory 
status under the MMPA and Endangered Species Act (ESA) and potential 
biological removal (PBR), where known. PBR is defined by the MMPA as 
the maximum number of animals, not including natural mortalities, that 
may be removed from a marine mammal stock while allowing that stock to 
reach or maintain its optimum sustainable population (as described in 
NMFS' SARs). While no serious injury or mortality is anticipated or 
authorized here, PBR and annual serious injury and mortality from 
anthropogenic sources are included here as gross indicators of the 
status of the species and other threats.
    Marine mammal abundance estimates presented in this document 
represent the total number of individuals that make up a given stock or 
the total number estimated within a particular study or survey area. 
NMFS' stock abundance estimates represent the total estimate of 
individuals within the geographic area, if known, that comprises that 
stock. For some species, this geographic area may extend beyond U.S. 
waters. All managed stocks in this region are assessed in NMFS' U.S. 
Atlantic and Gulf of Mexico SARs (e.g., Hayes et al., 2022). All values 
presented in Table 3 are the most recent available at the time of 
publication (available online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/draft-marine-mammal-stock-assessment-reports).

                                     Table 3--Marine Mammal Species \4\ Likely Impacted by the Specified Activities
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                         ESA/ MMPA status;   Stock abundance (CV,
             Common name                  Scientific name               Stock             strategic (Y/N)      Nmin, most recent       PBR     Annual M/
                                                                                                \1\          abundance survey) \2\               SI \3\
--------------------------------------------------------------------------------------------------------------------------------------------------------
                              Order Artiodactyla--Infraorder Cetacea--Odontoceti (toothed whales, dolphins, and porpoises)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Delphinidae:
    Atlantic white-sided dolphins...  Lagenorhynchus acutus..  Western North Atlantic.  -, -, N             93,233 (0.71, 54,443,         544         27
                                                                                                             2016).
    Common dolphins.................  Delphinus delphis......  Western North Atlantic.  -, -, N             172,974 (0.21,              1,452        390
                                                                                                             145,216, 2016).
Family Phocoenidae (porpoises):
    Harbor Porpoise.................  Phocoena phocoena......  Gulf of Maine/Bay of     -, -, N             95,543 (0.31, 74,034,         851        164
                                                                Fundy.                                       2016).
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                               Order Carnivora--Pinnipedia
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Phocidae (earless seals):
    Harbor Seal.....................  Phoca vitulina.........  Western North Atlantic.  -, -, N             61,336 (0.08, 57,637,       1,729        339
                                                                                                             2018).
    Gray Seal.......................  Halichoerus grypus.....  Western North Atlantic.  -, -, N             27,300 (0.22, 22,785,       1,389      4,453
                                                                                                             2016).
    Harp Seal.......................  Pagophilus               Western North Atlantic.  -, -, N             7.6 M (UNK, 7.1, 2019)    426,000    178,573
                                       groenlandicus.

[[Page 66139]]

 
    Hooded Seal.....................  Cystophora cristata....  Western North Atlantic.  -, -, N             593,500 (UNK, UNK,            UNK      1,680
                                                                                                             2005).
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Endangered Species Act (ESA) status: Endangered (E), Threatened (T)/MMPA status: Depleted (D). A dash (-) indicates that the species is not listed
  under the ESA or designated as depleted under the MMPA. Under the MMPA, a strategic stock is one for which the level of direct human-caused mortality
  exceeds PBR or which is determined to be declining and likely to be listed under the ESA within the foreseeable future. Any species or stock listed
  under the ESA is automatically designated under the MMPA as depleted and as a strategic stock.
\2\ NMFS marine mammal stock assessment reports online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments/ assessments/. CV is coefficient of variation; Nmin is the minimum estimate of stock abundance.
\3\ These values, found in NMFS's SARs, represent annual levels of human-caused mortality plus serious injury from all sources combined (e.g.,
  commercial fisheries, ship strike). Annual M/SI often cannot be determined precisely and is in some cases presented as a minimum value or range. A CV
  associated with estimated mortality due to commercial fisheries is presented in some cases.
\4\ Information on the classification of marine mammal species can be found on the web page for The Society for Marine Mammalogy's Committee on Taxonomy
  (https://marinemammalscience.org/science-and-publications/list-marine-mammal-species-subspecies/; Committee on Taxonomy (2022)).

    As indicated above, all seven species (with seven managed stocks) 
in Table 3 temporally and spatially co-occur with the activity to the 
degree that take is reasonably likely to occur. While several species 
of whales have been documented seasonally in New England waters, the 
spatial occurrence of these species is such that take is not expected 
to occur, and they are not discussed further beyond the explanation 
provided here. The humpback (Megaptera novaeangliae), fin (Balaenoptera 
physalus), sei (Balaenoptera borealis), sperm (Physeter macrocephalus) 
and North Atlantic right whales (Eubaleana glacialis) occur seasonally 
in the Atlantic Ocean, offshore of Rhode Island. However, due to the 
depths of Narragansett Bay and near shore location of the project area, 
these marine mammals are unlikely to occur in the project area. 
Therefore, OMAO did not request, and NMFS is not proposing to authorize 
takes of these species.

Atlantic White-Sided Dolphin

    Atlantic white-sided dolphins occur in the temperate waters of the 
North Atlantic and specifically off the coast of North Carolina to 
Maine in U.S. waters (Hayes et al., 2022). The Gulf of Maine population 
of white-sided dolphin primarily occurs in continental shelf waters 
from Hudson Canyon to Georges Bank, and in the Gulf of Maine and lower 
Bay of Fundy. From January to May, this population occurs in low 
numbers from Georges Bank to Jeffreys Ledge (off New Hampshire) with 
even lower numbers south of Georges Bank. They are most common from 
June through September from Georges Bank to lower Bay of Fundy, with 
densities declining from October through December (Payne and Heinemann, 
1990; Hayes et al., 2022).
    Since stranding recordings for the Atlantic white-sided dolphin 
began in Rhode Island in the late 1960s, this species has become the 
third most frequently recorded small cetacean. There are occasional 
unconfirmed opportunistic reports of white-sided dolphins in 
Narragansett Bay, typically in fall and winter. Atlantic white-sided 
dolphins in Rhode Island inhabit the continental shelf, with a slight 
tendency to occur in shallower water in the spring when they are most 
common (approximately 64 percent of records). Seasonal occurrence of 
Atlantic white-sided dolphins decreases significantly following spring 
with 21 percent of records in summer, 10 percent in winter, and 7.6 
percent in fall (Kenny and Vigness-Raposa, 2010).
    Mass strandings of up to 100 animals or more is common for this 
species. In an analysis of stranded marine mammals in Cape Cod and 
southeastern Massachusetts, Bogomolni et al. (2010) found that 69 
percent of stranded white-sided dolphins were involved in mass 
stranding events with no significant cause determined, and 21 percent 
were classified as disease-related. Impacts from contaminants and 
pesticides, as well as climate-related changes, pose the greatest 
threats for Atlantic white-sided dolphins.

Common Dolphin

    The common dolphin is one of the most widely distributed species of 
cetaceans, found world-wide in temperate and subtropical seas. In the 
North Atlantic, they are common along the shoreline of Massachusetts 
and at sea sightings have been concentrated over the continental shelf 
between the 100-meter (m) and 2000-m isobaths over prominent underwater 
topography and east to the mid-Atlantic Ridge. The common dolphin 
occurs from Cape Hatteras northeast to Georges Bank from mid-January to 
May and in the Gulf of Maine from mid-summer to autumn (Hayes et al., 
2022).
    Strandings occur year-round. In the stranding record for Rhode 
Island, common dolphins are the second most frequently stranded 
cetacean (exceeded only by harbor porpoises) and the most common 
delphinid. There were 23 strandings in Rhode Island between 1972 and 
2005 (Kenny and Vigness-Raposa, 2010). A short-beaked common dolphin 
was most recently recorded in Narragansett Bay in October of 2016 
(Hayes et al., 2022). There are no recent records of common dolphins 
far up rivers, however such occurrences would only show up in the 
stranding database if the stranding network responded, and there is no 
centralized clearinghouse for opportunistic sightings of that type. In 
Rhode Island, there are occasional opportunistic reports of common 
dolphins in Narragansett Bay up as far as the Providence River, usually 
in winter. The greatest threats for common dolphins include impacts 
from contaminants, anthropogenic sound, and climate change (Hayes et 
al., 2022).

Harbor Porpoise

    Harbor porpoises occur in northern temperate and subarctic coastal 
and offshore waters in both the Atlantic and Pacific Oceans. In the 
western North Atlantic, harbor porpoises occur in the northern Gulf of 
Maine and southern Bay of Fundy region in waters generally less than 
150 m deep, primarily during the summer (July to September). During 
fall (October to December) and spring (April to June), harbor porpoises 
are widely dispersed between New Jersey and Maine. Lower densities of 
harbor porpoise occur during the winter (January to March) in waters 
off New York to New Brunswick, Canada (Hayes et al., 2022).
    Harbor porpoises are the most stranded cetacean in Rhode Island. 
Their occurrence is strongly seasonal and the highest occurrence is in 
spring at approximately 70 percent of all

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records. Harbor porpoises may occur in Narragansett Bay during the 
winter, but reports are second- and third-hand anecdotal reports 
(Kenny, 2013). As harbor porpoises spend a significant amount of time 
in nearshore areas, harbor porpoises are vulnerable to contaminants, 
ship traffic, and physical habitat modifications in addition to fishery 
bycatch and sources of anthropogenic underwater noise (Hall et al., 
2006; Todd et al., 2015; Oakley et al., 2017; Hayes et al., 2022).

Harbor Seal

    Harbor seals occur in all nearshore waters of the North Atlantic 
and North Pacific Oceans and adjoining seas above approximately 
30[deg]N (Burns, 2009). They are year-round residents in the coastal 
waters of eastern Canada and Maine (Katona et al., 1993), occurring 
seasonally from southern New England to New Jersey from September 
through late May (Schneider and Payne, 1983; Schroeder, 2000; Rees et 
al., 2016, Toth et al., 2018). Harbor seals' northern movement occurs 
prior to pupping season that takes place from May through June along 
the Maine coast. In autumn to early winter, harbor seals move southward 
from the Bay of Fundy to southern New England and mid-Atlantic waters 
(Rosenfeld et al., 1988; Whitman and Payne, 1990; Jacobs and Terhune, 
2000; Hayes et al., 2022). Overall, there are five recognized 
subspecies of harbor seal, two of which occur in the Atlantic Ocean. 
The western Atlantic harbor seal is the subspecies likely to occur in 
the proposed project area. There is some uncertainly about the overall 
population stock structure of harbor seals in the western North 
Atlantic Ocean. However, it is theorized that harbor seals along the 
eastern U.S. and Canada are all from a single population (Temte et al., 
1991; Anderson and Olsen, 2010).
    Harbor seals are regularly observed around all coastal areas 
throughout Rhode Island, and occasionally well inland up bays, rivers, 
and streams. In general, rough estimates indicate that approximately 
100,000 harbor seals occur in New England waters (DeAngelis, 2020). 
Seals are very difficult to detect during surveys, since they tend to 
be solitary and the usual sighting cue is only the seal's head above 
the surface. Available data on harbor seals in New England are strongly 
dominated by stranding records, which comprise 446 of 507 total records 
for harbor seals (88 percent) (Kenny and Vigness-Raposa, 2010). Of the 
available records, 52.5 percent are in spring, 31.2 percent in winter, 
9.5 percent in summer, and 6.9 percent in fall. In Rhode Island, there 
are no records offshore of the 90-meter isobath. Based upon seasonal 
monitoring in Rhode Island, seals begin to arrive in Narragansett Bay 
in September, with numbers slowly increasing in March before dropping 
off sharply in April. By May, seals have left the Bay (DeAngelis, 
2020).
    Seasonal nearshore marine mammal surveys were conducted at NAVSTA 
Newport between May 2016 and February 2017. The surveys were conducted 
along the western shoreline of Coasters Harbor Island northward to 
Coggeshall Point and eastward to include Gould Island. The only species 
that was sighted during the survey was harbor seal. During the spring 
survey of 2016, one live harbor seal was sighted on May 12 and one 
harbor seal carcass was observed and reported to the Mystic Aquarium 
Stranding Network (Moll, et al., 2016, 2017; Navy, 2017b). A group of 
three harbor seals was sighted on February 1 2017, during the winter 
survey.
    In Rhode Island waters, harbor seals prefer to haul out on isolated 
intertidal rock ledges and outcrops. Numerous Naval Station employees 
have reported seals hauled out on an intertidal rock ledge named ``The 
Sisters,'' which is north-northwest of Coddington Point and 
approximately 3,500 ft (1,066.8 m) from the proposed project area (see 
Figure 4-1 of the application) (NUWC Division, 2011). This haulout site 
has been studied by the NUWC Division Newport since 2011 and has 
demonstrated a steady increase in use during winter months when harbor 
seals are present in the Bay. Harbor seals are rarely observed at ``The 
Sisters'' haulout in the early fall (September-October) but sighted in 
consistent numbers in mid-November (0-10 animals), and are regularly 
observed with a gradual increase of more than 20 animals until numbers 
peak in the upper 40s during March, typically at low tide. The number 
of harbor seals begin to drop off in April and by mid-May, they are not 
observed hauled out at all (DeAngelis, 2020). Haulout spaces at ``The 
Sisters'' haulout site is primarily influenced by tide level, swell, 
and wind direction (Moll et al., 2017; DeAngelis, 2020).
    In addition to ``The Sisters'' haul out, there are 22 haulout sites 
in Narragansett Bay (see Figure 4-1 in the application). During a 1 day 
Narragansett Bay-wide count in 2018, there were at least 423 seals 
observed and all 22 haulout sites were represented. Preliminary results 
from the Bay-wide count for 2019 recorded 572 harbor seals, which also 
included counts from Block Island (DeAngelis, 2020).

Gray Seal

    Gray seals within U.S. waters are from the western North Atlantic 
stock and are expected to be part of the eastern Canadian population. 
The western North Atlantic stock is centered in Canadian waters, 
including the Gulf of St. Lawrence and the Atlantic coasts of Nova 
Scotia, Newfoundland, and Labrador, Canada, and the northeast U.S. 
continental shelf (Hayes et al., 2022). In U.S. waters, year-round 
breeding of approximately 400 animals has been documented on areas of 
outer Cape Cod and Muskeget Island in Massachusetts.
    Gray seal occurrences in Rhode Island are mostly represented by 
stranding records--155 of 193 total records (80 percent). Gray seal 
records in the region are primarily from the spring (approximately 87 
percent), with much smaller numbers in all other seasons. Kenney and 
Vigness-Raposa (2010) found strandings to be broadly distributed along 
ocean-facing beaches in Long Island and Rhode Island, with a few spring 
records in Connecticut. Habitat use by gray seals in Rhode Island is 
poorly understood. They are seen mainly when stranded or hauled out, 
and are infrequently observed at sea. There are very few observations 
of gray seals in Rhode Island other than strandings. The annual numbers 
of gray seal strandings in the Rhode Island study area since 1993 have 
fluctuated markedly, from a low of 1 in 1999 to a high of 24 in 2011 
(Kenney, 2020). The very strong seasonality of gray seal occurrence in 
Rhode Island between March and June is linked to the timing of pupping 
in January and February. Most stranded individuals encountered in Rhode 
Island area appear to be post-weaning juveniles and starved or starving 
juveniles (Nawojchik, 2002; Kenney, 2005). Annual informal surveys 
conducted since 1994 observed a small number of gray seals in 
Narragansett Bay in 2016, although the majority of seals observed were 
harbor seals (ecoRI News, 2016).

Harp Seal

    The harp seal is a highly migratory species, and its range can 
extend from the Canadian Arctic to New Jersey (Sergeant, 1965; Stenson 
and Sjare, 1997; Hayes et al., 2021). Harp seals are classified into 
three stocks, which coincide with specific pupping sites on pack ice. 
These pupping sites are as follows: (1) Eastern Canada, including the 
areas off the coast of Newfoundland and Labrador and the area near the

[[Page 66141]]

Magdalen Islands in the Gulf of St. Lawrence; (2) the West Ice off 
eastern Greenland, and (3) the ice in the White Sea off the coast of 
Russia ((Lavigne and Kovacs, 1988; Bonner, 1990; Hayes et al., 2021). 
In U.S. waters, the species has an increasing presence in the coastal 
waters between Maine and New Jersey with a general presence from 
January through May (Hayes et al., 2021).
    Harp seals in Rhode Island are known almost exclusively from 
strandings (approximately 98 percent). Strandings are widespread on 
ocean-facing beaches throughout Long Island and Rhode Island and the 
records occur almost entirely during spring (approximately 68 percent) 
and winter (approximately 30 percent). Harp seals are nearly absent in 
summer and fall. Harp seals also make occasional appearances well 
inland up rivers (Kenny and Vigness-Raposa, 2010). During late winter 
of 2020, a healthy harp seal was observed hauled out and resting near 
``The Sisters'' haulout site (DeAngelis, 2020).

Hooded Seal

    The hooded seal is a highly migratory species, and its range can 
extend from the Canadian Arctic to as far south as Puerto Rico 
(Mignucci-Giannoni and Odell, 2001; Hayes et al., 2019). In U.S. 
waters, the species has an increasing presence in the coastal waters 
between Maine and Florida. Hooded seals in the U.S. are considered 
members of the western North Atlantic stock and generally occur in New 
England waters from January through May and further south off the 
southeast U.S. coast and in the Caribbean in the summer and fall 
seasons (McAlpine et al., 1999; Harris et al., 2001; and Mignucci-
Giannoni and Odell, 2001; Hayes et al., 2019).
    Hooded seal occurrences in Rhode Island are predominately from 
stranding records (approximately 99 percent). They are rare in summer 
and fall but most common in the area during spring and winter (45 
percent and 36 percent of all records, respectively) (Kenney, 2005; 
Kenny and Vigness-Raposa, 2010). Hooded seal strandings are broadly 
distributed across ocean-facing beaches in Rhode Island and they 
occasionally occur well up rivers, but less often than harp seals. 
Hooded seals have been recorded in Narragansett Bay but are considered 
occasional visitors and are expected to be the least encountered seal 
species in the Bay (RICRMC, 2010).

Marine Mammal Hearing

    Hearing is the most important sensory modality for marine mammals 
underwater, and exposure to anthropogenic sound can have deleterious 
effects. To appropriately assess the potential effects of exposure to 
sound, it is necessary to understand the frequency ranges marine 
mammals are able to hear. Not all marine mammal species have equal 
hearing capabilities (e.g., Richardson et al., 1995; Wartzok and 
Ketten, 1999; Au and Hastings, 2008). To reflect this, Southall et al. 
(2007, 2019) recommended that marine mammals be divided into hearing 
groups based on directly measured (behavioral or auditory evoked 
potential techniques) or estimated hearing ranges (behavioral response 
data, anatomical modeling, etc.). Note that no direct measurements of 
hearing ability have been successfully completed for mysticetes (i.e., 
low-frequency cetaceans). Subsequently, NMFS (2018) described 
generalized hearing ranges for these marine mammal hearing groups. 
Generalized hearing ranges were chosen based on the approximately 65 
decibel (dB) threshold from the normalized composite audiograms, with 
the exception for lower limits for low-frequency cetaceans where the 
lower bound was deemed to be biologically implausible and the lower 
bound from Southall et al. (2007) retained. Marine mammal hearing 
groups and their associated hearing ranges are provided in Table 4.

                  Table 4--Marine Mammal Hearing Groups
                              [NMFS, 2018]
------------------------------------------------------------------------
                                                    Generalized hearing
                  Hearing group                           range *
------------------------------------------------------------------------
Low-frequency (LF) cetaceans (baleen whales)....  7 Hz to 35 kHz.
Mid-frequency (MF) cetaceans (dolphins, toothed   150 Hz to 160 kHz.
 whales, beaked whales, bottlenose whales).
High-frequency (HF) cetaceans (true porpoises,    275 Hz to 160 kHz.
 Kogia, river dolphins, Cephalorhynchid,
 Lagenorhynchus cruciger & L. australis).
Phocid pinnipeds (PW) (underwater) (true seals).  50 Hz to 86 kHz.
Otariid pinnipeds (OW) (underwater) (sea lions    60 Hz to 39 kHz.
 and fur seals).
------------------------------------------------------------------------
* Represents the generalized hearing range for the entire group as a
  composite (i.e., all species within the group), where individual
  species' hearing ranges are typically not as broad. Generalized
  hearing range chosen based on ~65 dB threshold from normalized
  composite audiogram, with the exception for lower limits for LF
  cetaceans (Southall et al., 2007) and PW pinniped (approximation).

    The pinniped functional hearing group was modified from Southall et 
al. (2007) on the basis of data indicating that phocid species have 
consistently demonstrated an extended frequency range of hearing 
compared to otariids, especially in the higher frequency range 
(Hemil[auml] et al., 2006; Kastelein et al., 2009; Reichmuth and Holt, 
2013).
    For more detail concerning these groups and associated frequency 
ranges, please see NMFS (2018) for a review of available information.

Potential Effects of Specified Activities on Marine Mammals and Their 
Habitat

    This section provides a discussion of the ways that components of 
the specified activity may impact marine mammals and their habitat. The 
Estimated Take section later in this document includes a quantitative 
analysis of the number of individuals that are expected to be taken by 
this activity. The Negligible Impact Analysis and Determination section 
considers the content of this section, the Estimated Take section, and 
the Proposed Mitigation section, to draw conclusions regarding the 
likely impacts of these activities on the reproductive success or 
survivorship of individuals and whether those impacts are reasonably 
expected to, or reasonably likely to, adversely affect the species or 
stock through effect on annual rates of recruitment or survival.
    Acoustic effects on marine mammals during the specified activities 
can occur from vibratory and impact pile driving as well as rotary 
drilling and DTH mono-hammer events. The effects of underwater noise 
from OMAO's proposed activities have the potential to result in Level A 
and Level B harassment of marine mammals in the proposed action area.

Description of Sound Sources

    The marine soundscape is comprised of both ambient and 
anthropogenic sounds. Ambient sound is defined as the all-encompassing 
sound in a given

[[Page 66142]]

place and is usually a composite of sound from many sources both near 
and far (ANSI 1995). The sound level of an area is defined by the total 
acoustical energy being generated by known and unknown sources. These 
sources may include physical (e.g., waves, wind, precipitation, 
earthquakes, ice, atmospheric sound), biological (e.g., sounds produced 
by marine mammals, fish, and invertebrates), and anthropogenic sound 
(e.g., vessels, dredging, aircraft, construction).
    The sum of the various natural and anthropogenic sound sources at 
any given location and time--which comprise ``ambient'' or 
``background'' sound--depends not only on the source levels (as 
determined by current weather conditions and levels of biological and 
shipping activity) but also on the ability of sound to propagate 
through the environment. In turn, sound propagation is dependent on the 
spatially and temporally varying properties of the water column and sea 
floor, and is frequency-dependent. As a result of the dependence on a 
large number of varying factors, ambient sound levels can be expected 
to vary widely over both coarse and fine spatial and temporal scales. 
Sound levels at a given frequency and location can vary by 10-20 
decibels (dB) from day to day (Richardson et al., 1995). The result is 
that, depending on the source type and its intensity, sound from the 
specified activities may be a negligible addition to the local 
environment or could form a distinctive signal that may affect marine 
mammals.
    In-water construction activities associated with the project would 
include impact and vibratory pile driving, vibratory removal, and 
rotary drilling and DTH mono-hammer excavation events. The sounds 
produced by these activities fall into one of two general sound types: 
impulsive and non-impulsive. Impulsive sounds (e.g., explosions, sonic 
booms, impact pile driving) are typically transient, brief (less than 1 
second), broadband, and consist of high peak sound pressure with rapid 
rise time and rapid decay (ANSI, 1986; NIOSH, 1998; NMFS, 2018). Non-
impulsive sounds (e.g., machinery operations such as drilling or 
dredging, vibratory pile driving, underwater chainsaws, and active 
sonar systems) can be broadband, narrowband or tonal, brief or 
prolonged (continuous or intermittent), and typically do not have the 
high peak sound pressure with raid rise/decay time that impulsive 
sounds do (ANSI 1995; NIOSH 1998; NMFS 2018). DTH mono-hammer 
excavation includes the use of rotary drilling (non-impulsive sound 
source) and percussive hammering (impulsive sound source). The 
distinction between impulsive and non-impulsive sound sources 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).
    Three types of hammers would be used on this project, impact, 
vibratory and DTH mono-hammer. Impact hammers operate by repeatedly 
dropping and/or pushing a heavy piston onto a pile to drive the pile 
into the substrate. Sound generated by impact hammers is considered 
impulsive. Vibratory hammers install piles by vibrating them and 
allowing the weight of the hammer to push them into the sediment. 
Vibratory hammers produce non-impulsive, continuous sounds. Vibratory 
hammering generally produces sounds pressure levels (SPLs) 10 to 20 dB 
lower than impact pile driving of the same-sized pile (Oestman et al., 
2009). Rise time is slower, reducing the probability and severity of 
injury, and sound energy is distributed over a greater amount of time 
(Nedwell and Edwards, 2002; Carlson et al., 2005).
    DTH systems, involving both mono-hammers and cluster-hammers, and 
rotary drills will also be used during the proposed construction. In 
rotary drilling, the drill bit rotates on the rock while the drill rig 
applies pressure. The bit rotates and grinds continuously to fracture 
the rock and create a hole. Rotary drilling is considered an 
intermittent, non-impulsive noise source. A DTH hammer is essentially a 
drill bit that drills through the bedrock using a rotating function 
like a normal drill, in concert with a hammering mechanism operated by 
a pneumatic (or sometimes hydraulic) component integrated into to the 
DTH hammer to increase speed of progress through the substrate (i.e., 
it is similar to a ``hammer drill'' hand tool). Rock socketing involves 
using DTH equipment to create a hole in the bedrock inside which the 
pile is placed to give it lateral and longitudinal strength. The sounds 
produced by the DTH methods contain both a continuous, non-impulsive 
component from the drilling action and an impulsive component from the 
hammering effect. Therefore, we treat DTH systems as both impulsive and 
continuous, non-impulsive sound source types simultaneously.
    The likely or possible impacts of OMAO's proposed activities on 
marine mammals could be generated from both non-acoustic and acoustic 
stressors. Potential non-acoustic stressors include the physical 
presence of the equipment, vessels, and personnel; however, we expect 
that any animals that approach the project site(s) close enough to be 
harassed due to the presence of equipment or personnel would be within 
the Level A or Level B harassment zones from pile driving/removal and 
would already be subject to harassment from the in-water activities. 
Therefore, any impacts to marine mammals are expected to primarily be 
acoustic in nature. Acoustic stressors include heavy equipment 
operation during pile installation and removal (i.e., impact and 
vibratory pile driving and removal, rotary drilling, and DTH mono-
hammer excavation).

Acoustic Impacts

    The introduction of anthropogenic noise into the aquatic 
environment from pile driving and removal equipment is the primary 
means by which marine mammals may be harassed from OMAO's specified 
activities. In general, animals exposed to natural or anthropogenic 
sound may experience physical and psychological effects, ranging in 
magnitude from none to severe (Southall et al., 2007). Generally, 
exposure to pile driving and removal and other construction noise has 
the potential to result in auditory threshold shifts and behavioral 
reactions (e.g., avoidance, temporary cessation of foraging and 
vocalizing, changes in dive behavior). Exposure to anthropogenic noise 
can also lead to non-observable physiological responses such as an 
increase in stress hormones. Additional noise in a marine mammal's 
habitat can mask acoustic cues used by marine mammals to carry out 
daily functions such as communication and predator and prey detection. 
The effects of pile driving and demolition noise on marine mammals are 
dependent on several factors, including, but not limited to, sound type 
(e.g., impulsive vs. non-impulsive), the species, age and sex class 
(e.g., adult male vs. mother with calf), duration of exposure, the 
distance between the pile and the animal, received levels, behavior at 
time of exposure, and previous history with exposure (Wartzok et al., 
2003; Southall et al., 2007). Here we discuss physical auditory effects 
(threshold shifts) followed by behavioral effects and potential impacts 
on habitat.
    NMFS defines a noise-induced threshold shift (TS) as a change, 
usually an increase, in the threshold of audibility at a specified 
frequency or portion of an individual's hearing range above a 
previously established reference level (NMFS, 2018). The amount of 
threshold shift is customarily expressed in dB. A TS can be permanent 
or

[[Page 66143]]

temporary. As described in NMFS (2018), there are numerous factors to 
consider when examining the consequence of TS, including, but not 
limited to, the signal temporal pattern (e.g., impulsive or non-
impulsive), likelihood an individual would be exposed for a long enough 
duration or to a high enough level to induce a TS, the magnitude of the 
TS, time to recovery (seconds to minutes or hours to days), the 
frequency range of the exposure (i.e., spectral content), the hearing 
and vocalization frequency range of the exposed species relative to the 
signal's frequency spectrum (i.e., how animal uses sound within the 
frequency band of the signal; e.g., Kastelein et al., 2014), and the 
overlap between the animal and the source (e.g., spatial, temporal, and 
spectral).
    Permanent Threshold Shift (PTS)--NMFS defines PTS as a permanent, 
irreversible increase in the threshold of audibility at a specified 
frequency or portion of an individual's hearing range above a 
previously established reference level (NMFS, 2018). Available data 
from humans and other terrestrial mammals indicate that a 40 dB 
threshold shift approximates PTS onset (see Ward et al., 1958, 1959; 
Ward, 1960; Kryter et al., 1966; Miller, 1974; Henderson et al., 2008). 
PTS levels for marine mammals are estimates, because there are limited 
empirical data measuring PTS in marine mammals (e.g., Kastak et al., 
2008), largely due to the fact that, for various ethical reasons, 
experiments involving anthropogenic noise exposure at levels inducing 
PTS are not typically pursued or authorized (NMFS, 2018).
    Temporary Threshold Shift (TTS)--TTS is a temporary, reversible 
increase in the threshold of audibility at a specified frequency or 
portion of an individual's hearing range above a previously established 
reference level (NMFS, 2018). Based on data from cetacean TTS 
measurements (see Southall et al., 2007), a TTS of 6 dB is considered 
the minimum threshold shift clearly larger than any day-to-day or 
session-to-session variation in a subject's normal hearing ability 
(Schlundt et al., 2000; Finneran et al., 2000, 2002). As described in 
Finneran (2016), marine mammal studies have shown the amount of TTS 
increases with cumulative sound exposure level (SELcum) in 
an accelerating fashion: At low exposures with lower SELcum, 
the amount of TTS is typically small and the growth curves have shallow 
slopes. At exposures with higher SELcum, the growth curves 
become steeper and approach linear relationships with the noise SEL.
    Depending on the degree (elevation of threshold in dB), duration 
(i.e., recovery time), and frequency range of TTS, and the context in 
which it is experienced, TTS can have effects on marine mammals ranging 
from discountable to serious (similar to those discussed in Auditory 
Masking, below). For example, a marine mammal may be able to readily 
compensate for a brief, relatively small amount of TTS in a non-
critical frequency range that takes place during a time when the animal 
is traveling through the open ocean, where ambient noise is lower and 
there are not as many competing sounds present. Alternatively, a larger 
amount and longer duration of TTS sustained during time when 
communication is critical for successful mother/calf interactions could 
have more serious impacts. We note that reduced hearing sensitivity as 
a simple function of aging has been observed in marine mammals, as well 
as humans and other taxa (Southall et al., 2007), so we can infer that 
strategies exist for coping with this condition to some degree, though 
likely not without cost.
    Many studies have examined noise-induced hearing loss in marine 
mammals (see Finneran (2015) and Southall et al. (2019) for summaries). 
For cetaceans, published data on the onset of TTS are limited to the 
captive bottlenose dolphin (Tursiops truncatus), beluga whale 
(Delphinapterus leucas), harbor porpoise, and Yangtze finless porpoise 
(Neophocoena asiaeorientalis), and for pinnipeds in water, measurements 
of TTS are limited to harbor seals, elephant seals (Mirounga 
angustirostris), and California sea lions (Zalophus californianus). 
These studies examine hearing thresholds measured in marine mammals 
before and after exposure to intense sounds. The difference between the 
pre-exposure and post-exposure thresholds can be used to determine the 
amount of threshold shift at various post-exposure times. The amount 
and onset of TTS depends on the exposure frequency. Sounds at low 
frequencies, well below the region of best sensitivity, are less 
hazardous than those at higher frequencies, near the region of best 
sensitivity (Finneran and Schlundt, 2013). At low frequencies, onset-
TTS exposure levels are higher compared to those in the region of best 
sensitivity (i.e., a low frequency noise would need to be louder to 
cause TTS onset when TTS exposure level is higher), as shown for harbor 
porpoises and harbor seals (Kastelein et al., 2019a, 2019b, 2020a, 
2020b). In addition, TTS can accumulate across multiple exposures, but 
the resulting TTS will be less than the TTS from a single, continuous 
exposure with the same SEL (Finneran et al., 2010; Kastelein et al., 
2014; Kastelein et al., 2015a; Mooney et al., 2009). This means that 
TTS predictions based on the total, cumulative SEL will overestimate 
the amount of TTS from intermittent exposures such as sonars and 
impulsive sources. Nachtigall et al. (2018) and Finneran (2018) 
describe the measurements of hearing sensitivity of multiple odontocete 
species (bottlenose dolphin, harbor porpoise, beluga, and false killer 
whale (Pseudorca crassidens)) when a relatively loud sound was preceded 
by a warning sound. These captive animals were shown to reduce hearing 
sensitivity when warned of an impending intense sound. Based on these 
experimental observations of captive animals, the authors suggest that 
wild animals may dampen their hearing during prolonged exposures or if 
conditioned to anticipate intense sounds. Another study showed that 
echolocating animals (including odontocetes) might have anatomical 
specializations that might allow for conditioned hearing reduction and 
filtering of low-frequency ambient noise, including increased stiffness 
and control of middle ear structures and placement of inner ear 
structures (Ketten et al., 2021). Data available on noise-induced 
hearing loss for mysticetes are currently lacking (NMFS, 2018).
    Activities for this project include impact and vibratory pile 
driving, vibratory pile removal, rotary drilling, and DTH mono-hammer 
excavation. There would likely be pauses in activities producing the 
sound during each day. Given these pauses and the fact that many marine 
mammals are likely moving through the project areas and not remaining 
for extended periods of time, the potential for threshold shift 
declines.
    Behavioral harassment--Exposure to noise from pile driving and 
removal also has the potential to behaviorally disturb marine mammals. 
Behavioral responses to sound are highly variable and context-specific 
and any reactions depend on numerous intrinsic and extrinsic factors 
(e.g., species, state of maturity, experience, current activity, 
reproductive state, auditory sensitivity, time of day), as well as the 
interplay between factors (e.g., Richardson et al., 1995; Wartzok et 
al., 2003; Southall et al., 2007; Weilgart, 2007; Archer et al., 2010; 
Southall et al., 2021). If a marine mammal does react briefly to an 
underwater sound by changing its behavior or moving a small distance, 
the impacts of the change are unlikely to be

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significant to the individual, let alone the stock or population. 
However, if a sound source displaces marine mammals from an important 
feeding or breeding area for a prolonged period, impacts on individuals 
and populations could be significant (e.g., Lusseau and Bejder, 2007; 
Weilgart, 2007; NRC, 2005).
    The following subsections provide examples of behavioral responses 
that provide an idea of the variability in behavioral responses that 
would be expected given the differential sensitivities of marine mammal 
species to sound and the wide range of potential acoustic sources to 
which a marine mammal may be exposed. Behavioral responses that could 
occur for a given sound exposure should be determined from the 
literature that is available for each species, or extrapolated from 
closely related species when no information exists, along with 
contextual factors. Available studies show wide variation in response 
to underwater sound; therefore, it is difficult to predict specifically 
how any given sound in a particular instance might affect marine 
mammals perceiving the signal. There are broad categories of potential 
response, which we describe in greater detail here, that include 
alteration of dive behavior, alteration of foraging behavior, effects 
to respiration, interference with or alteration of vocalization, 
avoidance, and flight.
    Pinnipeds may increase their haul out time, possibly to avoid in-
water disturbance (Thorson and Reyff, 2006). Behavioral reactions can 
vary not only among individuals but also within an individual, 
depending on previous experience with a sound source, context, and 
numerous other factors (Ellison et al., 2012), and can vary depending 
on characteristics associated with the sound source (e.g., whether it 
is moving or stationary, number of sources, distance from the source). 
In general, pinnipeds seem more tolerant of, or at least habituate more 
quickly to, potentially disturbing underwater sound than do cetaceans, 
and generally seem to be less responsive to exposure to industrial 
sound than most cetaceans.
    Alteration of Dive Behavior--Changes in dive behavior can vary 
widely, and may consist of increased or decreased dive times and 
surface intervals as well as changes in the rates of ascent and descent 
during a dive (e.g., Frankel and Clark, 2000; Costa et al., 2003; Ng 
and Leung, 2003; Nowacek et al., 2004; Goldbogen et al., 2013). Seals 
exposed to non-impulsive sources with a received sound pressure level 
within the range of calculated exposures (142-193 dB re 1 [mu]Pa), have 
been shown to change their behavior by modifying diving activity and 
avoidance of the sound source (G[ouml]tz et al., 2010; Kvadsheim et 
al., 2010). Variations in dive behavior may reflect interruptions in 
biologically significant activities (e.g., foraging) or they may be of 
little biological significance. The impact of an alteration to dive 
behavior resulting from an acoustic exposure depends on what the animal 
is doing at the time of the exposure and the type and magnitude of the 
response.
    Alteration of Feeding Behavior--Disruption of feeding behavior can 
be difficult to correlate with anthropogenic sound exposure, so it is 
usually inferred by observed displacement from known foraging areas, 
the appearance of secondary indicators (e.g., bubble nets or sediment 
plumes), or changes in dive behavior. As for other types of behavioral 
response, the frequency, duration, and temporal pattern of signal 
presentation, as well as differences in species sensitivity, are likely 
contributing factors to differences in response in any given 
circumstance (e.g., Croll et al., 2001; Nowacek et al.; 2004; Madsen et 
al., 2006; Yazvenko et al., 2007; Melc[oacute]n et al., 2012). In 
addition, behavioral state of the animal plays a role in the type and 
severity of a behavioral response, such as disruption to foraging 
(e.g., Silve et al., 2016; Wensveen et al., 2017). A determination of 
whether foraging disruptions incur fitness consequences would require 
information on or estimates of the energetic requirements of the 
affected individuals and the relationship between prey availability, 
foraging effort and success, and the life history stage of the animal. 
Goldbogen et al. (2013) indicate that disruption of feeding and 
displacement could impact individual fitness and health. However, for 
this to be true, we would have to assume that an individual could not 
compensate for this lost feeding opportunity by either immediately 
feeding at another location, by feeding shortly after cessation of 
acoustic exposure, or by feeding at a later time. There is no 
indication this is the case, particularly since unconsumed prey would 
likely still be available in the environment in most cases following 
the cessation of acoustic exposure. Information on or estimates of the 
energetic requirements of the individuals and the relationship between 
prey availability, foraging effort and success, and the life history 
stage of the animal will help better inform a determination of whether 
foraging disruptions incur fitness consequences.
    Respiration--Respiration naturally varies with different behaviors, 
and variations in respiration rate as a function of acoustic exposure 
can be expected to co-occur with other behavioral reactions, such as a 
flight response or an alteration in diving. However, respiration rates 
in and of themselves may be representative of annoyance or an acute 
stress response. Studies with captive harbor porpoises showed increased 
respiration rates upon introduction of acoustic alarms (Kastelein et 
al., 2001; Kastelein et al., 2006a) and emissions for underwater data 
transmission (Kastelein et al., 2005). Various studies also have shown 
that species and signal characteristics are important factors in 
whether respiration rates are unaffected or change, again highlighting 
the importance in understanding species differences in the tolerance of 
underwater noise when determining the potential for impacts resulting 
from anthropogenic sound exposure (e.g., Kastelein et al., 2005, 2006, 
2018; Gailey et al., 2007; Isojunno et al., 2018).
    Vocalization--Marine mammals vocalize for different purposes and 
across multiple modes, such as whistling, echolocation click 
production, calling, and singing. Changes in vocalization behavior in 
response to anthropogenic noise can occur for any of these modes and 
may result from a need to compete with an increase in background noise 
or may reflect increased vigilance or a startle response. For example, 
in the presence of potentially masking signals, humpback whales and 
killer whales (Orcinus orca) have been observed to increase the length 
of their songs (Miller et al., 2000; Fristrup et al., 2003; Foote et 
al., 2004), while right whales have been observed to shift the 
frequency content of their calls upward while reducing the rate of 
calling in areas of increased anthropogenic noise (Parks et al., 2007; 
Rolland et al., 2012). Killer whales off the northwestern coast of the 
United States have been observed to increase the duration of primary 
calls once a threshold in observing vessel density (e.g., whale 
watching) was reached, which has been suggested as a response to 
increased masking noise produced by the vessels (Foote et al., 2004; 
NOAA, 2014). In some cases, however, animals may cease or alter sound 
production in response to underwater sound (e.g., Bowles et al., 1994; 
Castellote et al., 2012; Cerchio et al., 2014). Studies also 
demonstrate that even low levels of noise received far from the noise 
source can induce changes in vocalization and/or

[[Page 66145]]

behavioral responses (Blackwell et al., 2013, 2015).
    Avoidance--Avoidance is the displacement of an individual from an 
area or migration path as a result of the presence of a sound or other 
stressors, and is one of the most obvious manifestations of disturbance 
in marine mammals (Richardson et al., 1995). Avoidance is qualitatively 
different from the flight response, but also differs in the magnitude 
of the response (i.e., directed movement, rate of travel, etc.). Often 
avoidance is temporary, and animals return to the area once the noise 
has ceased. Acute avoidance responses have been observed in captive 
porpoises and pinnipeds exposed to a number of different sound sources 
(Kastelein et al., 2001; Finneran et al., 2003; Kastelein et al., 
2006a; Kastelein et al., 2006b; Kastelein et al., 2015b; Kastelein et 
al., 2015c; Kastelein et al., 2018). Short-term avoidance of seismic 
surveys, low frequency emissions, and acoustic deterrents have also 
been noted in wild populations of odontocetes (Bowles et al., 1994; 
Goold, 1996; Goold and Fish, 1998; Morton and Symonds, 2002; Hiley et 
al., 2021) and to some extent in mysticetes (Malme et al., 1984; 
McCauley et al., 2000; Gailey et al., 2007). Longer-term displacement 
is possible, however, which may lead to changes in abundance or 
distribution patterns of the affected species in the affected region if 
habituation to the presence of the sound does not occur (e.g., 
Blackwell et al., 2004; Bejder et al., 2006; Teilmann et al., 2006).
    Forney et al. (2017) described the potential effects of noise on 
marine mammal populations with high site fidelity, including 
displacement and auditory masking. In cases of Western gray whales 
(Eschrichtius robustus) (Weller et al., 2006) and beaked whales 
(Ziphius cavirostris), anthropogenic effects in areas where they are 
resident or exhibit site fidelity could cause severe biological 
consequences, in part because displacement may adversely affect 
foraging rates, reproduction, or health, while an overriding instinct 
to remain in the area could lead to more severe acute effects. 
Avoidance of overlap between disturbing noise and areas and/or times of 
particular importance for sensitive species may be critical to avoiding 
population-level impacts because (particularly for animals with high 
site fidelity) there may be a strong motivation to remain in the area 
despite negative impacts.
    Flight Response--A flight response is a dramatic change in normal 
movement to a directed and rapid movement away from the perceived 
location of a sound source. The flight response differs from other 
avoidance responses in the intensity of the response (e.g., directed 
movement, rate of travel). Relatively little information on flight 
responses of marine mammals to anthropogenic signals exist, although 
observations of flight responses to the presence of predators have 
occurred (Connor and Heithaus, 1996). The result of a flight response 
could range from brief, temporary exertion and displacement from the 
area where the signal provokes flight to, in extreme cases, marine 
mammal strandings (Evans and England, 2001). There are limited data on 
flight response for marine mammals in water; however, there are 
examples of this response in species on land. For instance, the 
probability of flight responses in Dall's sheep Ovis dalli dalli (Frid, 
2003), hauled out ringed seals (Phoca hispida) (Born et al., 1999), 
Pacific brant (Branta bernicla nigricans), and Canada geese (B. 
canadensis) increased as a helicopter or fixed-wing aircraft more 
directly approached groups of these animals (Ward et al., 1999). 
However, it should be noted that response to a perceived predator does 
not necessarily invoke flight (Ford and Reeves, 2008), and whether 
individuals are solitary or in groups may influence the response.
    Behavioral disturbance can also impact marine mammals in more 
subtle ways. Increased vigilance may result in costs related to 
diversion of focus and attention (i.e., when a response consists of 
increased vigilance, it may come at the cost of decreased attention to 
other critical behaviors such as foraging or resting). These effects 
have generally not been observed in marine mammals, but studies 
involving fish and terrestrial animals have shown that increased 
vigilance may substantially reduce feeding rates and efficiency (e.g., 
Beauchamp and Livoreil, 1997; Fritz et al., 2002; Purser and Radford, 
2011). In addition, chronic disturbance can cause population declines 
through reduction of fitness (e.g., decline in body condition) and 
subsequent reduction in reproductive success, survival, or both (e.g., 
Harrington and Veitch, 1992; Daan et al., 1996; Bradshaw et al., 1998).
    Many animals perform vital functions, such as feeding, resting, 
traveling, and socializing, on a diel cycle (24-hour cycle). Disruption 
of such functions resulting from reactions to stressors such as sound 
exposure are more likely to be significant if they last more than one 
diel cycle or recur on subsequent days (Southall et al., 2007). 
Consequently, a behavioral response lasting less than one day and not 
recurring on subsequent days is not considered particularly severe 
unless it could directly affect reproduction or survival (Southall et 
al., 2007). Note that there is a difference between multi-day 
substantive behavioral reactions and multi-day anthropogenic 
activities. For example, just because an activity lasts for multiple 
days does not necessarily mean that individual animals are either 
exposed to activity-related stressors for multiple days or, further, 
exposed in a manner resulting in sustained multi-day substantive 
behavioral responses.
    Many of the contextual factors resulting from the behavioral 
response studies (e.g., close approaches by multiple vessels or 
tagging) would not occur during the proposed action. In 2016, the 
Alaska Department of Transportation and Public Facilities (ADOT&PF) 
documented observations of marine mammals during construction 
activities (i.e., pile driving) at the Kodiak Ferry Dock (see 80 FR 
60636, October 7, 2015). In the marine mammal monitoring report for 
that project (ABR, 2016), 1,281 Steller sea lions were observed within 
the Level B disturbance zone during pile driving or drilling (i.e., 
documented as Level B harassment take). Of these, 19 individuals 
demonstrated an alert behavior, 7 were fleeing, and 19 swam away from 
the project site. All other animals (98 percent) were engaged in 
activities such as milling, foraging, or fighting and did not change 
their behavior. Three harbor seals were observed within the disturbance 
zone during pile driving activities; none of them displayed disturbance 
behaviors. Fifteen killer whales and three harbor porpoise were also 
observed within the Level B harassment zone during pile driving. The 
killer whales were travelling or milling while all harbor porpoises 
were travelling. No signs of disturbance were noted for either of these 
species. The proposed action involves impact and vibratory pile 
driving, vibratory pile removal, rotary drilling, and DTH mono-hammer 
excavation. Given the similarities in activities and habitat (e.g., 
cool-temperate waters, industrialized area), we expect similar 
behavioral responses from the same and similar species affected by 
OMAO's proposed action. That is, disturbance, if any, is likely to be 
temporary and localized (e.g., small area movements).
    To assess the strength of behavioral changes and responses to 
external sounds and SPLs associated with changes in behavior, Southall 
et al., (2007) developed and utilized a severity scale, which is a 10 
point scale ranging from no effect (labeled 0), effects not likely to 
influence vital rates (low; labeled from 1 to 3), effects that could 
affect vital rates (moderate; labeled 4 to

[[Page 66146]]

6), to effects that were thought likely to influence vital rates (high; 
labeled 7 to 9). Southall et al., (2021) updated the severity scale by 
integrating behavioral context (i.e., survival, reproduction, and 
foraging) into severity assessment. For non-impulsive sounds (i.e., 
similar to the sources used during the proposed action), data suggest 
that exposures of pinnipeds to sources between 90 and 140 dB re 1 
[mu]Pa do not elicit strong behavioral responses; no data were 
available for exposures at higher received levels for Southall et al., 
(2007) to include in the severity scale analysis. Reactions of harbor 
seals were the only available data for which the responses could be 
ranked on the severity scale. For reactions that were recorded, the 
majority (17 of 18 individuals/groups) were ranked on the severity 
scale as a 4 (defined as moderate change in movement, brief shift in 
group distribution, or moderate change in vocal behavior) or lower; the 
remaining response was ranked as a 6 (defined as minor or moderate 
avoidance of the sound source).
    Habituation--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). Animals are most 
likely to habituate to sounds that are predictable and unvarying. It is 
important to note that habituation is appropriately considered as a 
``progressive reduction in response to stimuli that are perceived as 
neither aversive nor beneficial,'' rather than as, more generally, 
moderation in response to human disturbance (Bejder et al., 2009). 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. As noted, behavioral state may affect the type of 
response. For example, animals that are resting may show greater 
behavioral change in response to disturbing sound levels than animals 
that are highly motivated to remain in an area for feeding (Richardson 
et al., 1995; NRC, 2003; Wartzok et al., 2003). Controlled experiments 
with captive marine mammals have 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 impulsive sound sources (typically seismic airguns or acoustic 
harassment devices) have been varied but often consist of avoidance 
behavior or other behavioral changes suggesting discomfort (Morton and 
Symonds, 2002; see also Richardson et al., 1995; Nowacek et al., 2007).
    Stress responses--An animal's perception of a threat may be 
sufficient to trigger stress responses consisting of some combination 
of behavioral responses, autonomic nervous system responses, 
neuroendocrine responses, or immune responses (e.g., Seyle, 1950; 
Moberg, 2000). In many cases, an animal's first and sometimes most 
economical (in terms of energetic costs) response is behavioral 
avoidance of the potential stressor. Autonomic nervous system responses 
to stress typically involve changes in heart rate, blood pressure, and 
gastrointestinal activity. These responses have a relatively short 
duration and may or may not have a significant long-term effect on an 
animal's fitness.
    Neuroendocrine stress responses often involve the hypothalamus-
pituitary-adrenal system. Virtually all neuroendocrine functions that 
are affected by stress--including immune competence, reproduction, 
metabolism, and behavior--are regulated by pituitary hormones. Stress-
induced changes in the secretion of pituitary hormones have been 
implicated in failed reproduction, altered metabolism, reduced immune 
competence, and behavioral disturbance (e.g., Moberg, 1987; Blecha, 
2000). Increases in the circulation of glucocorticoids are also equated 
with stress (Romano et al., 2004).
    The primary distinction between stress (which is adaptive and does 
not normally place an animal at risk) and ``distress'' is the cost of 
the response. During a stress response, an animal uses glycogen stores 
that can be quickly replenished once the stress is alleviated. In such 
circumstances, the cost of the stress response would not pose serious 
fitness consequences. However, when an animal does not have sufficient 
energy reserves to satisfy the energetic costs of a stress response, 
energy resources must be diverted from other functions. This state of 
distress will last until the animal replenishes its energetic reserves 
sufficient to restore normal function.
    Relationships between these physiological mechanisms, animal 
behavior, and the costs of stress responses are well-studied through 
controlled experiments and for both laboratory and free-ranging animals 
(e.g., Holberton et al., 1996; Hood et al., 1998; Jessop et al., 2003; 
Krausman et al., 2004; Lankford et al., 2005). Stress responses due to 
exposure to anthropogenic sounds or other stressors and their effects 
on marine mammals have also been reviewed (Fair and Becker 2000; Romano 
et al., 2002b) and, more rarely, studied in wild populations (e.g., 
Romano et al., 2002a). For example, Rolland et al. (2012) found that 
noise reduction from reduced ship traffic in the Bay of Fundy was 
associated with decreased stress in North Atlantic right whales. These 
and other studies lead to a reasonable expectation that some marine 
mammals will experience physiological stress responses upon exposure to 
acoustic stressors and that it is possible that some of these would be 
classified as ``distress.'' In addition, any animal experiencing TTS 
would likely also experience stress responses (NRC, 2003), however 
distress is an unlikely result of these projects based on observations 
of marine mammals during previous, similar projects.
    Auditory Masking--Sound can disrupt behavior through masking, or 
interfering with, an animal's ability to detect, recognize, or 
discriminate between acoustic signals of interest (e.g., those used for 
intraspecific communication and social interactions, prey detection, 
predator avoidance, navigation) (Richardson et al., 1995). Masking 
occurs when the receipt of a sound is interfered with by another 
coincident sound at similar frequencies and at similar or higher 
intensity, and may occur whether the sound is natural (e.g., snapping 
shrimp, wind, waves, precipitation) or anthropogenic (e.g., pile 
driving, shipping, sonar, seismic exploration) in origin. The ability 
of a noise source to mask biologically important sounds depends on the 
characteristics of both the noise source and the signal of interest 
(e.g., signal-to-noise ratio, temporal variability, direction), in 
relation to each other and to an animal's hearing abilities (e.g., 
sensitivity, frequency range, critical ratios, frequency 
discrimination, directional discrimination, age or TTS hearing loss), 
and existing ambient noise and propagation conditions. Masking of 
natural sounds can result when human activities produce high levels of 
background sound at frequencies important to marine mammals. 
Conversely, if the background level of underwater sound is high (e.g., 
on a day with strong wind and high waves), an anthropogenic sound 
source would not be detectable as far away as would be possible under 
quieter conditions and would itself be masked. Narragansett Bay 
supports cargo vessel traffic as well as numerous recreational and 
fishing vessels, and background sound levels in the proposed project 
area are already elevated.
    Airborne Acoustic Effects--Pinnipeds that occur near the project 
site could be

[[Page 66147]]

exposed to airborne sounds associated with pile driving and removal 
that have the potential to cause behavioral harassment, depending on 
their distance from pile driving activities. Cetaceans are not expected 
to be exposed to airborne sounds that would result in harassment as 
defined under the MMPA.
    Airborne noise would primarily be an issue for pinnipeds that are 
swimming or hauled out near the project site within the range of noise 
levels elevated above the acoustic criteria. We recognize that 
pinnipeds in the water could be exposed to airborne sound that may 
result in behavioral harassment when looking with their heads above 
water. Most likely, airborne sound would cause behavioral responses 
similar to those discussed above in relation to underwater sound. 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 the area and move 
further from the source. However, these animals would likely previously 
have been `taken' because of exposure to underwater sound above the 
behavioral harassment thresholds, which are generally larger than those 
associated with airborne sound. Thus, the behavioral harassment of 
these animals is already accounted for in these estimates of potential 
take. Therefore, we do not believe that authorization of incidental 
take resulting from airborne sound for pinnipeds is warranted, and 
airborne sound is not discussed further.

Marine Mammal Habitat Effects

    OMAO's proposed construction activities could have localized, 
temporary impacts on marine mammal habitat, including prey, by 
increasing in-water sound pressure levels and slightly decreasing water 
quality. Increased noise levels may affect acoustic habitat (see 
masking discussion above) and adversely affect marine mammal prey in 
the vicinity of the project areas (see discussion below). Elevated 
levels of underwater noise would ensonify the project areas where both 
fishes and mammals occur and could affect foraging success. 
Additionally, marine mammals may avoid the area during construction; 
however, displacement due to noise is expected to be temporary and is 
not expected to result in long-term effects to the individuals or 
populations.
    A temporary and localized increase in turbidity near the seafloor 
would occur in the immediate area surrounding the area where piles are 
installed or removed. In general, turbidity associated with pile 
installation is localized to about a 25-ft (7.6 m) radius around the 
pile (Everitt et al., 1980). Turbidity and sedimentation effects are 
expected to be short-term, minor, and localized. Re-suspended sediments 
in Coddington Cove are expected to remain in Coddington Cove due to the 
circular nature of the currents with ambient conditions returning a few 
hours after completion of construction. Cetaceans are not expected to 
be close enough to the pile driving areas to experience effects of 
turbidity, and any pinnipeds could avoid localized areas of turbidity. 
Therefore, we expect the impact from increased turbidity levels to be 
discountable to marine mammals and do not discuss it further.

In-Water Construction Effects on Potential Foraging Habitat

    The area likely impacted by the project is relatively small 
compared to the available habitat in Narragansett Bay. In addition, the 
area is highly influenced by anthropogenic activities and habitat in 
this area has been previously disturbed by as a part of offshore 
remediation activities. The total seafloor area affected by pile 
installation and removal is a small area compared to the vast amount of 
habitat available to marine mammals in the area. All marine mammal 
species using habitat near the proposed project area are primarily 
transiting the area. There are no known foraging or haulout areas 
within one half mile of the proposed project area. Furthermore, pile 
driving and removal at the project site would not obstruct long-term 
movements or migration of marine mammals.
    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 and marine mammal 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 or marine mammals of the disturbed area would still leave 
significantly large areas of fish and marine mammal foraging habitat in 
the nearby vicinity.

Effects on Potential Prey

    Sound may affect marine mammals through impacts on the abundance, 
behavior, or distribution of prey species (e.g., fish). Marine mammal 
prey varies by species, season, and location. Here, we describe studies 
regarding the effects of noise on known marine mammal prey.
    Fish utilize the soundscape and components of sound in their 
environment to perform important functions such as foraging, predator 
avoidance, mating, and spawning (e.g., Zelick and Mann, 1999; Fay, 
2009). Depending on their hearing anatomy and peripheral sensory 
structures, which vary among species, fishes hear sounds using pressure 
and particle motion sensitivity capabilities and detect the motion of 
surrounding water (Fay et al., 2008). The potential effects of noise on 
fishes depends on the overlapping frequency range, distance from the 
sound source, water depth of exposure, and species-specific hearing 
sensitivity, anatomy, and physiology. Key impacts to fishes may include 
behavioral responses, hearing damage, barotrauma (pressure-related 
injuries), and mortality.
    Fish react to sounds which are especially strong and/or 
intermittent low-frequency sounds, and behavioral responses such as 
flight or avoidance are the most likely effects. Short duration, sharp 
sounds can cause overt or subtle changes in fish behavior and local 
distribution. The reaction of fish to noise depends on the 
physiological state of the fish, past exposures, motivation (e.g., 
feeding, spawning, migration), and other environmental factors. 
Hastings and Popper (2005) identified several studies that suggest fish 
may relocate to avoid certain areas of sound energy. Additional studies 
have documented effects of pile driving on fish; several are based on 
studies in support of large, multiyear bridge construction projects 
(e.g., Scholik and Yan, 2001, 2002; Popper and Hastings, 2009). Several 
studies have demonstrated that impulse sounds might affect the 
distribution and behavior of some fishes, potentially impacting 
foraging opportunities or increasing energetic costs (e.g., Fewtrell 
and McCauley, 2012; Pearson et al., 1992; Skalski et al., 1992; 
Santulli et al., 1999; Paxton et al., 2017). However, some studies have 
shown no or slight reaction to impulse sounds (e.g., Pena et al., 2013; 
Wardle et al., 2001; Jorgenson and Gyselman, 2009).
    SPLs of sufficient strength have been known to cause injury to fish 
and fish mortality. However, in most fish species, hair cells in the 
ear continuously regenerate and loss of auditory function likely is 
restored when damaged cells are replaced with new cells. Halvorsen et 
al. (2012a) showed that a TTS of 4-6 dB was recoverable within 24 hours 
for one species. Impacts would be most severe when the individual fish 
is close to the source and when the duration of exposure is long. 
Injury caused by

[[Page 66148]]

barotrauma can range from slight to severe and can cause death, and is 
most likely for fish with swim bladders. Barotrauma injuries have been 
documented during controlled exposure to impact pile driving (Halvorsen 
et al., 2012b; Casper et al., 2013).
    The most likely impact to fishes from pile driving and removal and 
construction 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.
    Construction activities have the potential to have adverse impacts 
on forage fish in the project area in the form of increased turbidity. 
Forage fish form a significant prey base for many marine mammal species 
that occur in the project area. Increased turbidity is expected to 
occur in the immediate vicinity (on the order of 10 ft (3 m) or less) 
of construction activities. Turbidity within the water column has the 
potential to reduce the level of oxygen in the water and irritate the 
gills of prey fish in the proposed project area. However, fish in the 
proposed project area would be able to move away from and avoid the 
areas where increase turbidity may occur. Given the limited area 
affected and ability of fish to move to other areas, any effects on 
forage fish are expected to be minor or negligible.
    In summary, given the short daily duration of sound associated with 
individual pile driving and removal events and the relatively small 
areas being affected, pile driving and removal activities associated 
with the proposed actions are not likely to have a permanent, adverse 
effect on any fish habitat, or populations of fish species. Any 
behavioral avoidance by fish of the disturbed area would still leave 
significantly large areas of fish and marine mammal foraging habitat in 
the nearby vicinity. Thus, we conclude that impacts of the specified 
activities are not likely to have more than short-term adverse effects 
on any prey habitat or populations of prey species. Further, any 
impacts to marine mammal habitat are not expected to result in 
significant or long-term consequences for individual marine mammals, or 
to contribute to adverse impacts on their populations.

Estimated Take

    This section provides an estimate of the number of incidental takes 
proposed for authorization through this IHA, which will inform both 
NMFS' consideration of ``small numbers'' and the negligible impact 
determinations.
    Harassment is the only type of take expected to result from these 
activities. Except with respect to certain activities not pertinent 
here, section 3(18) of 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).
    Authorized takes would primarily be by Level B harassment, as use 
of the acoustic sources (i.e., pile driving and removal, DTH, and 
rotary drilling) has the potential to result in disruption of 
behavioral patterns for individual marine mammals. There is also some 
potential for auditory injury (Level A harassment) to result, primarily 
for high frequency species and phocids because predicted auditory 
injury zones are larger than for mid-frequency species. Auditory injury 
is unlikely to occur for mid-frequency species. The proposed mitigation 
and monitoring measures are expected to minimize the severity of the 
taking to the extent practicable.
    As described previously, no serious injury or mortality is 
anticipated or proposed to be authorized for this activity. Below we 
describe how the proposed take numbers are estimated.
    For acoustic impacts, generally speaking, we estimate take by 
considering: (1) acoustic thresholds above which NMFS believes the best 
available science indicates marine mammals will be behaviorally 
harassed or incur some degree of permanent hearing impairment; (2) the 
area or volume of water that will be ensonified above these levels in a 
day; (3) the density or occurrence of marine mammals within these 
ensonified areas; and, (4) the number of days of activities. We note 
that while these factors can contribute to a basic calculation to 
provide an initial prediction of potential takes, additional 
information that can qualitatively inform take estimates is also 
sometimes available (e.g., previous monitoring results or average group 
size). Below, we describe the factors considered here in more detail 
and present the proposed take estimates.

Acoustic Thresholds

    NMFS recommends the use of acoustic thresholds that identify the 
received level of underwater sound above which exposed marine mammals 
would be reasonably expected to be behaviorally harassed (equated to 
Level B harassment) or to incur PTS of some degree (equated to Level A 
harassment). Thresholds have also been developed identifying the 
received level of in-air sound above which exposed pinnipeds would 
likely be behaviorally harassed.
    Level B Harassment--Though significantly driven by received level, 
the onset of behavioral disturbance from anthropogenic noise exposure 
is also informed to varying degrees by other factors related to the 
source or exposure context (e.g., frequency, predictability, duty 
cycle, duration of the exposure, signal-to-noise ratio, distance to the 
source), the environment (e.g., bathymetry, other noises in the area, 
predators in the area), and the receiving animals (hearing, motivation, 
experience, demography, life stage, depth) and can be difficult to 
predict (e.g., Southall et al., 2007, 2021, Ellison et al., 2012). 
Based on what the available science indicates and the practical need to 
use a threshold based on a metric that is both predictable and 
measurable for most activities, NMFS typically uses a generalized 
acoustic threshold based on received level to estimate the onset of 
behavioral harassment. NMFS generally predicts that marine mammals are 
likely to be behaviorally harassed in a manner considered to be Level B 
harassment when exposed to underwater anthropogenic noise above root-
mean-squared pressure received levels (RMS SPL) of 120 dB (referenced 
to 1 micropascal (re 1 [mu]Pa)) for continuous (e.g., vibratory pile-
driving, drilling) and above RMS SPL 160 dB re 1 [mu]Pa for non-
explosive impulsive (e.g., seismic airguns) or intermittent (e.g., 
scientific sonar) sources. Generally speaking, Level B harassment take 
estimates based on these behavioral harassment thresholds are expected 
to include any likely takes by TTS as, in most cases, the likelihood of 
TTS occurs at distances from the source less than those at which 
behavioral harassment is likely. TTS of a sufficient degree can 
manifest as behavioral harassment, as reduced hearing sensitivity and 
the potential reduced opportunities to detect important signals 
(conspecific communication, predators, prey) may result in changes in 
behavior patterns that would not otherwise occur.
    OMAO's proposed activities includes the use of continuous 
(vibratory hammer/rotary drill/DTH mono-hammer) and impulsive (impact 
hammer/DTH mono-hammer) sources, and therefore the RMS SPL thresholds 
of 120 and 160 dB re 1 [mu]Pa are applicable.

[[Page 66149]]

    Level A Harassment--NMFS' Technical Guidance for Assessing the 
Effects of Anthropogenic Sound on Marine Mammal Hearing (Version 2.0) 
(Technical Guidance, 2018) identifies dual criteria to assess auditory 
injury (Level A harassment) to five different marine mammal groups 
(based on hearing sensitivity) as a result of exposure to noise from 
two different types of sources (impulsive or non-impulsive). OMAO's 
proposed activity includes the use of impulsive (impact hammer/DTH 
mono-hammer) and non-impulsive (vibratory hammer/rotary drill/DTH mono-
hammer) sources.
    These thresholds are provided in the table below. The references, 
analysis, and methodology used in the development of the thresholds are 
described in NMFS' 2018 Technical Guidance, which may be accessed at: 
www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance.

                     Table 5--Thresholds Identifying the Onset of Permanent Threshold Shift
----------------------------------------------------------------------------------------------------------------
                                                         PTS onset thresholds * (received level)
             Hearing group              ------------------------------------------------------------------------
                                                  Impulsive                         Non-impulsive
----------------------------------------------------------------------------------------------------------------
Low-Frequency (LF) Cetaceans...........  Cell 1: Lp,0-pk,flat: 219   Cell 2: LE,p,LF,24h: 199 dB.
                                          dB; LE,p,LF,24h: 183 dB.
Mid-Frequency (MF) Cetaceans...........  Cell 3: Lp,0-pk,flat: 230   Cell 4: LE,p,MF,24h: 198 dB.
                                          dB; LE,p,MF,24h: 185 dB.
High-Frequency (HF) Cetaceans..........  Cell 5: Lp,0-pk,flat: 202   Cell 6: LE,p,HF,24h: 173 dB.
                                          dB; LE,p,HF,24h: 155 dB.
Phocid Pinnipeds (PW) (Underwater).....  Cell 7: Lp,0-pk.flat: 218   Cell 8: LE,p,PW,24h: 201 dB.
                                          dB; LE,p,PW,24h: 185 dB.
Otariid Pinnipeds (OW) (Underwater)....  Cell 9: Lp,0-pk,flat: 232   Cell 10: LE,p,OW,24h: 219 dB.
                                          dB; LE,p,OW,24h: 203 dB.
----------------------------------------------------------------------------------------------------------------
* Dual metric thresholds for impulsive sounds: Use whichever results in the largest isopleth for calculating PTS
  onset. If a non-impulsive sound has the potential of exceeding the peak sound pressure level thresholds
  associated with impulsive sounds, these thresholds are recommended for consideration.
Note: Peak sound pressure level (Lp,0-pk) has a reference value of 1 [mu]Pa, and weighted cumulative sound
  exposure level (LE,p) has a reference value of 1[mu]Pa\2\s. In this Table, thresholds are abbreviated to be
  more reflective of International Organization for Standardization standards (ISO 2017). The subscript ``flat''
  is being included to indicate peak sound pressure are flat weighted or unweighted within the generalized
  hearing range of marine mammals (i.e., 7 Hz to 160 kHz). The subscript associated with cumulative sound
  exposure level thresholds indicates the designated marine mammal auditory weighting function (LF, MF, and HF
  cetaceans, and PW and OW pinnipeds) and that the recommended accumulation period is 24 hours. The weighted
  cumulative sound exposure level thresholds could be exceeded in a multitude of ways (i.e., varying exposure
  levels and durations, duty cycle). When possible, it is valuable for action proponents to indicate the
  conditions under which these thresholds will be exceeded.

Ensonified Area

    Here, we describe operational and environmental parameters of the 
activity that are used in estimating the area ensonified above the 
acoustic thresholds, including source levels and transmission loss 
coefficient.
    The sound field in the project area is the existing background 
noise plus additional construction noise from the proposed project. 
Marine mammals are expected to be affected via sound generated by the 
primary components of the project (i.e., impact pile driving, vibratory 
pile driving, vibratory pile removal, rotary drilling, and DTH).
    The intensity of underwater sound is greatly influenced by factors 
such as the size and type of piles, type of driver or drill, and the 
physical environment in which the activity takes place. In order to 
calculate distances to the Level A harassment and Level B harassment 
thresholds for the methods and piles being used in this project, NMFS 
used representative source levels (Table 6) from acoustic monitoring at 
other locations.

                                                     Table 6--Source Levels for Proposed Activities
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                  SEL (dB re 1
             Method                         Pile type             Pile diameter   Peak (dB re 1   RMS (dB re 1    [mu]Pa 2-sec          Reference
                                                                                     [mu]Pa)         [mu]Pa)          sec)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Vibratory Extraction............  Steel pipe \1\...............            12''             171             155             155  Caltrans 2020, Table
                                                                                                                                  1.2-1d.
                                  Timber.......................            12''              NA             152              NA  NMFS 2021a, Table 4.
Vibratory Installation..........  Steel pipe...................            18''              NA         162 \2\             162  NAVFAC Mid-Atlantic
                                                                                                                                  2019, Table 6-4.
                                  Sheet pile...................     Z26-700 \3\              NA             156              NA  NMFS 2019, p.37846.
                                  Steel pipe...................            30''              NA             167             167  Navy 2015, p.14.
                                  Casing/shaft for steel pipe..            36''              NA             175             175  NAVFAC Mid-Atlantic
                                                                                                                                  2019, Table 6-4.
DTH Mono-hammer.................  Steel pipe...................            18''             172             167             146  Egger, 2021; Guan and
                                                                                                                                  Miner 2020; Heyvaert
                                                                                                                                  and Reyff, 2021.
                                  Casing/shaft for steel pipe..        36'' \4\             194             167             164  Reyff and Heyvaert
                                                                                                                                  2019; Reyff 2020; and
                                                                                                                                  Denes et al. 2019.
Rotary Drilling.................  Steel pipe...................   18'' and 30''              NA             154              NA  Dazey et al. 2012.
Impact Install..................  Steel pipe \5\...............            18''             208             187             176  Caltrans 2020, Table
                                                                                                                                  1.2-1a.
                                  Steel pipe...................            30''             211             196             181  NAVFAC Southwest 2020,
                                                                                                                                  p.A-4.
Vibratory Installation/           Steel pipe...................            16''              NA             162             162  NAVFAC Mid-Atlantic
 Extraction.                                                                                                                      2019, Table 6-4.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ 13-inch steel pipe used as proxy because data were not available for vibratory install/extract of 12-inch steel pipe.
\2\ Although conservative, this 162 dB RMS is consistent with source level value used for 18-inch steel pipe in for Dry Dock 1 at Portsmouth Naval
  Shipyard (84 FR 13252, April 4, 2019).
\3\ 30-inch steel pipe pile used as the proxy source for vibratory driving of steel sheet piles because data were not available for Z26-700 (Navy 2015
  [p. 14]).
\4\ Guidance from NMFS states: For each metric, select the highest SL provided among these listed references (Reyff and Heyvaert, 2019); (Reyff J.,
  2020); (Denes et al., 2019).
\5\ Impact install of 20-inch steel pipe used as proxy because data were not available for 18-inch.

[[Page 66150]]

 
Notes: All SPLs are unattenuated; dB = decibels; NA = Not applicable/Not available; RMS = root mean square; SEL = sound exposure level; Caltrans =
  California Department of Transportation; NAVFAC = Naval Facilities Engineering Systems Command; dB re 1 [mu]Pa = dB referenced to a pressure of 1
  microPascal, measures underwater SPL. dB re 1 [mu]Pa2-sec = dB referenced to a pressure of 1 microPascal squared per second, measures underwater SEL.
Single strike SEL are the proxy source levels presented for impact pile driving and were used to calculate distances to PTS. All data referenced at 10
  meters.

    NMFS recommends treating DTH systems as both impulsive and 
continuous, non-impulsive sound source types simultaneously. Thus, 
impulsive thresholds are used to evaluate Level A harassment, and 
continuous thresholds are used to evaluate Level B harassment. With 
regards to DTH mono-hammers, NMFS recommends proxy levels for Level A 
harassment based on available data regarding DTH systems of similar 
sized piles and holes (Denes et al., 2019; Guan and Miner, 2020; Reyff 
and Heyvaert, 2019; Reyff, 2020; Heyvaert and Reyff, 2021) (Table 1 
includes number of piles and duration; Table 6 includes sound pressure 
levels for each pile type). At the time of the Navy's application 
submission, NMFS recommended that the RMS sound pressure level at 10 m 
should be 167 dB when evaluating Level B harassment (Heyvaert and 
Reyff, 2021 as cited in NMFS 2021b) for all DTH pile/hole sizes. 
However, since that time, NMFS has received additional clarifying 
information regarding DTH data presented in Reyff and Heyvaert (2019) 
and Reyff (2020) that allows for different RMS sound pressure levels at 
10 m to be recommended for piles/holes of varying diameters. Therefore, 
NMFS proposes to use the following proxy RMS sound pressure levels at 
10 m to evaluate Level B harassment from this sound source in this 
analysis (Table 6): 167 dB RMS for the 18-inch steel pipe piles 
(Heyvaert and Reyff, 2021) and 174 dB RMS for the 36 inch steel shafts 
(Reyff and Heyvaert, 2019; Reyff, 2020).

Level B Harassment Zones

    Transmission loss (TL) 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 general formula for underwater TL is:

TL = B * log10 (R1/R2),

Where:

TL = transmission loss in dB
B = transmission loss coefficient; for practical spreading equals 15
R1 = the distance of the modeled SPL from the driven 
pile, and
R2 = the distance from the driven pile of the initial 
measurement.

    The recommended TL coefficient for most nearshore environments is 
the practical spreading value of 15. This value results in an expected 
propagation environment that would lie between spherical and 
cylindrical spreading loss conditions, known as practical spreading. As 
is common practice in coastal waters, here we assume practical 
spreading (4.5 dB reduction in sound level for each doubling of 
distance). Practical spreading was used to determine sound propagation 
for this project.
    The TL model described above was used to calculate the expected 
noise propagation from vibratory pile driving/extracting, impact pile 
driving, rotary drilling, and DTH mono-hammer excavation using 
representative source levels to estimate the harassment zones or area 
exceeding the noise criteria. Utilizing the described practical 
spreading model, NMFS calculated the Level B isopleths shown in Tables 
7 and 8. The largest calculated Level B isopleth, with the exception of 
concurrent activities, discussed below, is 46,416 m for the vibratory 
installation of the 36'' steel casing/shaft guide piles with rock 
socket to build the small boat floating dock; however, this distance is 
truncated by shoreline in all directions, so sound would not reach the 
full distance of the calculated Level B harassment isopleth. This 
activity would generate a maximum ensonified area of 3.31 km\2\ (Table 
8).

Level A Harassment Zones

    The ensonified area associated with Level A harassment is 
technically more challenging to predict due to the need to account for 
a duration component. Therefore, NMFS developed an optional User 
Spreadsheet tool to accompany the Technical Guidance that can be used 
to relatively simply predict an isopleth distance for use in 
conjunction with marine mammal density or occurrence to help predict 
potential takes. We note that because of some of the assumptions 
included in the methods underlying this optional tool, we anticipate 
that the resulting isopleth estimates are typically going to be 
overestimates of some degree, which may result in an overestimate of 
potential take by Level A harassment. However, this optional tool 
offers the best way to estimate isopleth distances when more 
sophisticated modeling methods are not available or practical. For 
stationary sources such as pile driving, the optional User Spreadsheet 
tool predicts the distance at which, if a marine mammal remained at 
that distance for the duration of the activity, it would be expected to 
incur PTS. Inputs used in the optional User Spreadsheet tool are 
reported in Tables 1 (number piles/day and duration to drive a single 
pile) and 6 (source levels/distance to source levels). The resulting 
estimated isopleths are reported below in Tables 7 and 8. The largest 
Level A isopleth would be generated by the impact driving of the 30'' 
steel pipe pile at the proposed pier for high-frequency cetaceans 
(3,500.3 m; Table 7). This activity would have a maximum ensonified 
area of 6.49 km\2\ (Table 7). Excluding concurrent activities, 
described below, the largest calculated Level B isopleth would be 
generated by the vibratory installation of the 36'' steel casing/shaft 
guide piles at the proposed small boat floating dock (46,416 m; Table 
8), though as noted above, this distance would be truncated by 
shoreline in all directions, so sound would not reach the full distance 
of the calculated Level B harassment isopleth. This activity would have 
a maximum ensonified area of 3.31 km\2\ (Table 8).

[[Page 66151]]



                         Table 7--Maximum Distances to Level A Harassment and Level B Harassment Thresholds for Impulsive Sound
                                                           [Impact Hammer and DTH Mono-Hammer]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                  Level A (PTS onset) harassment              Level B
                                                                                         ------------------------------------------------  (behavioral)
                                                                                                                                            harassment
                                                                                              Maximum         Maximum         Maximum    ---------------
                                                                                            distance to     distance to     distance to       Maximum
                                                                                           185 dB SELcum   155 dB SELcum   185 dB SELcum   distance 160
              Structure                   Pile size and type             Activity          threshold(m)/   threshold(m)/   threshold(m)/    dB RMS SPL
                                                                                              area of         area of         area of      (120 dB DTH)
                                                                                            harassment      harassment      harassment    threshold (m)/
                                                                                           zone (km\2\)    zone (km\2\)    zone (km\2\)       area of
                                                                                                                                            harassment
                                                                                                                                           zone (km\2\)
                                                                                             MF cetacean     HF cetacean          Phocid      All Marine
                                                                                                                                                 Mammals
--------------------------------------------------------------------------------------------------------------------------------------------------------
Bulkhead construction (Combination     18'' steel pipe.........  Impact Install.........     48.5/0.0037    1,624.7/0.66      729.9/0.21        631/0.16
 Pipe/Z-pile).
                                                                 DTH Mono-Hammer........    4.6/0.000033     154.2/0.028     69.3/0.0075     13,594/3.31
Trestle (Bents 1-18).................  18'' steel pipe.........  Impact Install.........     25.2/0.0020      844.9/1.21      379.6/0.38        631/0.82
Trestle (Bent 19)....................  30'' steel pipe.........  Impact Install.........      65.8/0.014    2,205.0/3.72      990.7/1.47      2,512/4.44
Pier.................................  30'' steel pipe.........  Impact Install.........     104.5/0.034    3,500.3/6.49    1,572.6/2.50      2,512/4.44
Gangway support piles (small boat      18'' steel pipe.........  Impact Install.........    19.3/0.00058      644.8/0.17     289.7/0.049        631/0.16
 floating dock).
 Small Boat Floating Dock              36'' Steel Casing/Shaft   Impact Install.........      35.5/0.002    1,189.5/0.45      534.4/0.12      3,415/2.14
                                        with Rock Socket (Guide
                                        Pile).
                                                                 DTH Mono-Hammer........       73/0.0084    2,444.5/1.21    1,098.2/0.42     13,594/3.31
--------------------------------------------------------------------------------------------------------------------------------------------------------
Notes: dB = decibel; DTH = down-the-hole; dB RMS SPL = decibel root mean square sound pressure. level; dB SELcum = cumulative sound exposure level; m =
  meter; PTS = Permanent Threshold Shift; km\2\ = square kilometer.


                            Table 8--Maximum Distances to Level A Harassment and Level B Harassment Thresholds for Continuous
                                                             [Vibratory Hammer/Rotary Drill]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                  Level A (PTS onset) harassment              Level B
                                                                                         ------------------------------------------------  (behavioral)
                                                                                                                                            harassment
                                                                                              Maximum         Maximum         Maximum    ---------------
                                                                                            distance to     distance to     distance to       Maximum
                                                                                           198 dB SELcum   173 dB SELcum   201 dB SELcum   distance 120
              Structure                   Pile size and type             Activity          threshold(m)/   threshold(m)/   threshold(m)/    dB RMS SPL
                                                                                              area of         area of         area of      (120 dB DTH)
                                                                                            harassment      harassment      harassment    threshold (m)/
                                                                                           zone (km\2\)    zone (km\2\)    zone (km\2\)       area of
                                                                                                                                            harassment
                                                                                                                                           zone (km\2\)
                                                                                             MF cetacean     HF cetacean          Phocid      All Marine
                                                                                                                                                 Mammals
--------------------------------------------------------------------------------------------------------------------------------------------------------
Abandoned guide piles along bulkhead.  12'' steel pipe.........  Vibratory Extract......           0.3/0    5.3/0.000044    2.2/0.000008      2,514/1.26
Floating dock demolition (Timber       12'' timber.............  Vibratory Extract......           0.2/0      4/0.000025    1.7/0.000005      1,359/0.53
 Guide Piles).
Bulkhead construction (Combination     18'' steel pipe.........  Vibratory Install......    1.8/0.000005     29.7/0.0014    12.2/0.00023      6,310/3.31
 Pipe/Z-pile).
                                       Steel sheet Z26-700.....  Vibratory Install......    0.7/0.000001    11.8/0.00022    4.9/0.000038      2,512/1.26
                                       16'' steel pipe template  Vibratory Install/         1.1/0.000002    18.7/0.00055    7.7/0.000093      6,310/3.31
                                        piles.                    Extract.
Trestle (Bents 1-18).................  18'' steel pipe.........  Vibratory Install......    0.7/0.000002    11.8/0.00044    4.8/0.000072      6,310/8.53
                                       18'' steel pipe hole....  Rotary Drill...........           0.0/0    0.6/0.000001    0.4/0.000001      1,848/2.98
                                       16'' steel pipe template  Vibratory Install/         1.1/0.000004     18.7/0.0011     7.7/0.00019      6,310/8.53
                                        piles.                    Extract.
Trestle (Bent 19)....................  30'' steel pipe.........  Vibratory Install......    2.0/0.000013     33.2/0.0034    13.7/0.00059     13,594/8.53
                                       16'' steel pipe template  Vibratory Install/         1.1/0.000004     18.7/0.0011     7.7/0.00019      6,310/8.53
                                        piles.                    Extract.
Pier.................................  30'' steel pipe.........  Vibratory Install......    3.2/0.000032     52.8/0.0087     21.7/0.0015     13,594/8.53
                                       30'' hole...............  Rotary Drill...........           0.0/0    0.6/0.000001    0.4/0.000001      1,848/2.98
                                       16'' steel pipe template  Vibratory Install/         1.1/0.000004     18.7/0.0011     7.7/0.00019      6,310/8.53
                                        piles.                    Extract.
Fender Piles.........................  16'' steel pipe.........  Vibratory Install......    0.9/0.000003    14.3/0.00064     5.9/0.00011      6,310/8.53
                                       16'' steel pipe template  Vibratory Install/         1.1/0.000004     18.7/0.0011     7.7/0.00019      6,310/8.53
                                        piles.                    Extract.
Gangway support piles (small boat      18'' steel pipe.........  Vibratory Install......    0.7/0.000001    11.8/0.00022    4.8/0.000036      6,310/3.31
 floating dock).
Small Boat Floating Dock.............  36'' Steel Casing/Shaft   Vibratory Install......    5.2/0.000042      86.6/0.012      35.6/0.002     46,416/3.31
                                        Guide Piles with Rock
                                        Socket.
                                       16'' steel pipe template  Vibratory Install/         1.1/0.000002    18.7/0.00055    7.7/0.000093      6,310/3.31
                                        piles.                    Extract.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Notes: dB = decibel; dB RMS SPL = decibel root mean square sound pressure level; dB SELcum = cumulative sound exposure level; m = meter; PTS = Permanent
  Threshold Shift; km\2\ = square kilometer.

Concurrent Activities

    Simultaneous use of two or three impact, vibratory, or DTH hammers, 
or rotary drills, could occur (potential combinations described in 
Table 1) and may result in increased sound source levels and harassment 
zone sizes, given the proximity of the structure sites and the rules of 
decibel addition (Table 9).
    NMFS (2018b) handles overlapping sound fields created by the use of 
more

[[Page 66152]]

than one hammer differently for impulsive (impact hammer and Level A 
harassment zones for drilling with a DTH hammer) and continuous sound 
sources (vibratory hammer, rotary drill, and Level B harassment zones 
for drilling with a DTH hammer (Table 9) and differently for impulsive 
sources with rapid impulse rates of multiple strikes per second (DTH) 
and slow impulse rates (impact hammering) (NMFS 2021). It is unlikely 
that the two impact hammers will strike at the same instant, and 
therefore, the SPLs will not be adjusted regardless of the distance 
between impact hammers. In this case, each impact hammer will be 
considered to have its own independent Level A harassment and Level B 
harassment zones.
    When two DTH hammers operate simultaneously their continuous sound 
components overlap completely in time. When the Level B isopleth of one 
DTH sound source encompasses the isopleth of another DTH sound source, 
the sources are considered additive and combined using the rules for 
combining sound source levels generated during pile installation, 
described in Table 9.

               Table 9--Rules for Combining Sound Source Levels Generated During Pile Installation
----------------------------------------------------------------------------------------------------------------
            Hammer types                   Difference in SSL           Level A zones           Level B zones
----------------------------------------------------------------------------------------------------------------
Vibratory, Impact...................  Any.......................  Use impact zones......  Use largest zone.
Impact, Impact......................  Any.......................  Use zones for each      Use zone for each pile
                                                                   pile size and number    size.
                                                                   of strikes.
Vibratory, Vibratory Rotary drill,    0 or 1 dB.................  Add 3 dB to the higher  Add 3 dB to the higher
 or DTH, DTH.                                                      source level.           source level.
                                      2 or 3 dB.................  Add 2 dB to the higher  Add 2 dB to the higher
                                                                   source level.           source level.
                                      4 to 9 dB.................  Add 1 dB to the higher  Add 1 dB to the higher
                                                                   source level.           source level.
                                      10 dB or more.............  Add 0 dB to the higher  Add 0 dB to the higher
                                                                   source level.           source level.
----------------------------------------------------------------------------------------------------------------
Note: The method is based on a method created by Washington State Department of Transportation (WSDOT 2020) and
  has been updated and modified by NMFS.

    When two continuous noise sources have overlapping sound fields, 
there is potential for higher sound levels than for non-overlapping 
sources. When two or more continuous noise sources are used 
simultaneously, and the isopleth of one sound source encompasses the 
isopleth of another sound source, the sources are considered additive 
and source levels are combined using the rules of decibel addition 
(Table 9; NMFS 2021c).
    For simultaneous use of three or more continuous sound sources, 
NMFS first identifies the three overlapping sources with the highest 
sound source level. Then, using the rules for combining sound source 
levels generated during pile installation (Table 9), NMFS determines 
the difference between the lower two source levels, and adds the 
appropriate number of decibels to the higher source level of the two. 
Then, NMFS calculates the difference between the newly calculated 
source level and the highest source level of the three identified in 
the first step, and again, adds the appropriate number of decibels to 
the highest source level of the three.
    For example, with overlapping isopleths from 24'', 36'', and 42'' 
diameter steel pipe piles with sound source levels of 161, 167, and 168 
dB RMS respectively, NMFS would first calculate the difference between 
the 24'' and 36'' source levels (167 dB-161 dB = 6 dB. Then, given that 
the difference is 6 dB, as described in Table 9, NMFS would then add 1 
dB to the highest of the two sound source levels (167 dB), for a 
combined noise level of 168 dB. Next, NMFS calculates the difference 
between the newly calculated 168 dB and the sound source level of the 
42'' steel pile (168 dB). Since 168 dB-168 dB = 0 dB, 3 dB is added to 
the highest value (168 dB + 3 dB = 171 dB). Therefore, for the 
combination of 24'', 36'', and 42'' steel pipe piles, zones would be 
calculated using a combined sound source level of 171 dB.
    If an impact hammer and a vibratory hammer are used concurrently, 
the largest Level B harassment zone generated by either hammer would 
apply, and the Level A harassment zone generated by the impact hammer 
would apply. Simultaneous use of two or more impact hammers does not 
require source level additions as it is unlikely that two hammers would 
strike at the same exact instant. Thus, sound source levels are not 
adjusted regardless of distance, and the zones for each individual 
activity apply.
    For activity combinations that do require sound source level 
adjustment, Table 10 shows the revised proxy source levels for 
concurrent activities based upon the rules for combining sound source 
levels generated during pile installation, described in Table 9. 
Resulting Level A harassment and Level B harassment zones for 
concurrent activities are summarized in Table 11. The maximum Level A 
harassment isopleth would be 2,444.5 m for high-frequency cetaceans 
generated by concurrent use of two vibratory pile drivers and DTH mono-
hammer during installation of 36'' shafts for the small boat floating 
dock (Table 11). The maximum Level B harassment isopleth would be 
54,117 m for the concurrent use of DTH mono-hammer and two vibratory 
pile drivers for installation of 36'' shafts for the small boat 
floating dock (Table 11).

  Table 10--Proxy Values for Simultaneous Use of Non-Impulsive Sources
------------------------------------------------------------------------
          Structure                 Activity and proxy         New proxy
------------------------------------------------------------------------
Bulkhead....................  Vibratory Install 16-inch       165 dB RMS
                               steel pipe piles--162 dB RMS.
                              Vibratory Install 18-inch
                               steel pipe piles--162 dB RMS.
                              Vibratory Install 18-inch       168 dB RMS
                               steel pipe piles--162 dB.
                              DTH Install 18-inch steel pipe
                               piles--167 dB.
------------------------------------------------------------------------

[[Page 66153]]

 
Bulkhead and Trestle........  Vibratory Install/extract 16-   166 dB RMS
                               inch steel pipe piles--162 dB
                               RMS.
                              Vibratory Install Z26-700
                               sheet piles--156 dB RMS.
                              Vibratory Install 18-inch
                               steel pipe piles--162 dB RMS.
                              Vibratory Install/extract 16-   163 dB RMS
                               inch steel pipe piles--162 dB
                               RMS.
                              Vibratory Install Z26-700
                               sheet piles--156 dB RMS.
                              Rotary Drill 18-inch steel
                               pipe piles--154 dB RMS.
------------------------------------------------------------------------
Pier........................  Vibratory Install/extract 16-   168 dB RMS
                               inch steel pipe piles--162 dB
                               RMS.
                              Vibratory Install 30-inch
                               steel pipe piles--167 dB RMS.
                              Vibratory Install/extract 16-   163 dB RMS
                               inch steel pipe piles--162 dB
                               RMS.
                              Rotary Drill 30-inch steel
                               pipe piles--154 dB RMS.
------------------------------------------------------------------------
Pier Fender Piles and Small   Vibratory Install/extract 16-   165 dB RMS
 Boat Floating Dock.           inch steel pipe piles--162 dB
                               RMS.
                              Vibratory Install 18-inch
                               steel pipe piles--162 dB RMS.
                              Vibratory Install/extract 16-   175 dB RMs
                               inch steel pipe piles--162 dB
                               RMS.
                              Vibratory Install 36-inch
                               steel pipe piles--175 dB RMS.
                              Vibratory Install 36-inch       176 dB
                               steel casing--175 dB.
                              DTH Install 36-inch steel
                               casing--167 dB.
------------------------------------------------------------------------


                           Table 11--Maximum Distances to Level A and Level B Harassment Thresholds for Concurrent Activities
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                              Level A (PTS onset) harassment                 Level B
                                                                                  ------------------------------------------------------   (behavioral)
                                                                                                                                            harassment
                                                                                   Maximum distance  Maximum distance  Maximum distance ----------------
                                                                                     to continuous     to continuous     to continuous       Maximum
                                                                        Total       198 dB SELcum;    173 dB SELcum;    201 dB SELcum;   distance 120 dB
          Structure             Pile sizes and       Activity        production       DTH 185 dB        DTH 155 dB        DTH 185 dB         RMS SPL
                                     type                               days            SELcum            SELcum            SELcum        threshold (m)/
                                                                                    thresholds (m)/   thresholds (m)/   thresholds (m)/      area of
                                                                                        area of           Area of           area of      harassment zone
                                                                                    harassment zone   harassment zone   harassment zone      (km\2\)
                                                                                        (km\2\)           (km\2\)           (km\2\)      (continuous and
                                                                                                                                               DTH)
                                                                                   MF cetacean.....  HF cetacean.....  Phocid..........
--------------------------------------------------------------------------------------------------------------------------------------------------------
Bulkhead.....................  Install of 16-    Install/Extract               15  3.7/0.000021....  61.6/0.0060.....  25.3/0.001......  10,000/3.31
                                inch and 18-      using two
                                inch steel pipe   Vibratory Pile
                                piles.            Drivers.
--------------------------------------------------------------------------------------------------------------------------------------------------------
                               Install of 18-    Install using                 12  Vibratory: 1.8/   Vibratory: 29.7/  Vibratory: 12.2/  15,848.93/3.31
                                inch steel pile.  two Vibratory                     0.000005 DTH:     0.0014 DTH:       0.00023 DTH:
                                                  Pile Drivers                      4.6/0.000033.     154.2/0.028.      69.3/0.0075.
                                                  and DTH mono-
                                                  hammer.
Bulkhead and Trestle.........  Install of 16-    Install/Extract               15  4.1/0.000026....  68.3/0.0073.....  28.1/0.0012.....  10,000/3.31
                                inch and 18-      using three
                                inch steel pipe   Vibratory Pile
                                and Z26-700       Drivers.
                                steel sheet
                                piles.
                                                 Install/Extract               14  2.9/0.000013....  47.8/0.0036.....  19.7/0.00061....  7,356/3.31
                                                  using two
                                                  Vibratory Pile
                                                  Drivers and a
                                                  Rotary Drill.
Pier.........................  Install of 16-    Install/Extract               30  5.9/0.00011.....  97.6/0.030......  40.1/0.0050.....  15,849/8.53
                                and 30-inch       using two
                                steel pipe.       Vibratory Pile
                                                  Drivers.
                                                 Install/Extract               27  2.0/0.0031......  33.1/0.0034.....  13.6/0.00058....  7,356/8.53
                                                  using a
                                                  vibratory pile
                                                  driver and
                                                  rotary drill.
Pier Fender Piles and Gangway  Install of 16-    Install/Extract               17  2.3/0.000017....  38.8/0.0047.....  16.0/0.0008.....  10,000/8.53
 Support for Small Boat         and 18-inch       using two
 Floating Dock.                 steel pipe.       Vibratory Pile
                                                  Drivers.
                               Install of 16-    Install using                 20  9.6/0.00029.....  159.5/0.080.....  65.6/0.013......  46,416/8.53
                                inch steel pipe   two Vibratory
                                and 36-inch       Pile Drivers.
                                shafts.

[[Page 66154]]

 
                               Install of 36-    Install using                  2  Vibratory: 5.2/   Vibratory: 86.6/  Vibratory: 35.6/  DTH: 54,117/
                                inch shafts.      two Vibratory                     0.000042 DTH:     0.012 DTH:        0.002 DTH:        8.53
                                                  Pile Drivers                      73/0.0084.        2,444.5/1.21.     1,098.2/0.42.
                                                  and DTH mono-
                                                  hammer.
--------------------------------------------------------------------------------------------------------------------------------------------------------
dB RMS SPL = decibel root mean square sound pressure level; dB SELcum = cumulative sound exposure level; m = meter; PTS = Permanent Threshold Shift;
  km\2\ = square kilometer.

    The Level B harassment zones in Table 11 were calculated based upon 
the adjusted source levels for simultaneous construction activities 
(Table 10). OMAO has not proposed any scenarios for concurrent work in 
which the Level A harassment isopleths would need to be adjusted from 
that calculated for single sources. Regarding implications for Level A 
harassment zones when multiple vibratory hammers, or vibratory hammers 
and rotary drills, are operating concurrently, given the small size of 
the estimated Level A harassment isopleths for all hearing groups 
during vibratory pile driving, the zones of any two hammers or hammer 
and drill are not expected to overlap. Therefore, compounding effects 
of multiple vibratory hammers operating concurrently are not 
anticipated, and NMFS has treated each source independently.
    Regarding implications for Level A harassment zones when vibratory 
hammers are operating concurrently with a DTH hammer, combining 
isopleths for these sources is difficult for a variety of reasons. 
First, vibratory pile driving relies upon non-impulsive PTS thresholds, 
while DTH hammers use impulsive thresholds. Second, vibratory pile 
driving accounts for the duration to drive a pile, while DTH account 
for strikes per pile. Thus, it is difficult to measure sound on the 
same scale and combine isopleths from these impulsive and non-
impulsive, continuous sources. Therefore, NMFS has treated each source 
independently at this time.
    Regarding implications for impact hammers used in combination with 
a vibratory hammer or DTH hammer, the likelihood of these multiple 
sources' isopleths completely overlapping in time is slim primarily 
because impact pile driving is intermittent. Furthermore, non-
impulsive, continuous sources rely upon non-impulsive TTS/PTS 
thresholds, while impact pile driving uses impulsive thresholds, making 
it difficult to calculate isopleths that may overlap from impact 
driving and the simultaneous action of a non-impulsive continuous 
source or one with multiple strikes per second. Thus, with such slim 
potential for multiple different sources' isopleths to overlap in space 
and time, specifications should be entered as ``normal'' into the User 
Spreadsheet for each individual source separately.

Marine Mammal Occurrence

    In this section we provide information about the occurrence of 
marine mammals, including density or other relevant information that 
will inform the take calculations. Potential exposures to construction 
noise for each acoustic threshold were estimated using marine mammal 
density estimates (N) from the Navy Marine Species Density Database 
(NMSDD) (Navy, 2017a). OMAO evaluated data reflecting monthly densities 
of each species to determine minimum, maximum, and average annual 
densities within Narragansett Bay. Table 12 summarizes the average 
annual densities of species that may be impacted by the proposed 
construction activities, with the exception of harbor seals as the 
density value for this species in the table represents the maximum 
density value for seals.

    Table 12--Average Densities by Species Used in Exposure Analysis
------------------------------------------------------------------------
                                                        Average density
                                                        in project area
                       Species                            (species per
                                                             km\2\)
------------------------------------------------------------------------
Atlantic White-sided Dolphin.........................              0.003
Common Dolphin.......................................              0.011
Harbor Porpoise......................................              0.012
Harbor Seal..........................................              0.623
Gray Seal............................................              0.131
Harp Seal............................................               0.05
Hooded Seal..........................................              0.001
------------------------------------------------------------------------

    The NMSDD models reflect densities for seals as a guild due to 
difficulty in distinguishing these species at sea. Harbor seal is 
expected to be the most common pinniped in Narragansett Bay with year-
round occurrence (Kenney and Vigness-Raposa, 2010). Therefore, OMAO 
used the maximum density for the seal guild for harbor seal. Gray seals 
are the second most common seal to be observed in Rhode Island waters 
and, based on stranding records, are commonly observed during the 
spring to early summer and occasionally observed during other months of 
the year (Kenney, 2020). Therefore, the average density for the seal 
guild was used for gray seal occurrence in Narragansett Bay. Minimum 
densities for the seal guild were used for harp seal and hooded seals 
as they are considered occasional visitors in Narragansett Bay

[[Page 66155]]

but are rare in comparison to harbor and gray seals (Kenney, 2015). 
NMFS has carefully reviewed and concurs with the use of these densities 
proposed by OMAO.

Take Estimation

    Here we describe how the information provided above is synthesized 
to produce a quantitative estimate of the take that is reasonably 
likely to occur and proposed for authorization.
    For each species, OMAO multiplied the average annual density by the 
largest ensonified area (Tables 7, 8, 11) and the maximum days of 
activity (Tables 7, 8, 11) (take estimate = N x ensonified area x days 
of pile driving) in order to calculate estimated take by Level A 
harassment and Level B harassment. OMAO used the pile type, size, and 
construction method that produce the largest isopleth to estimate 
exposure of marine mammals to noise impacts. The exposure estimate was 
rounded to the nearest whole number at the end of the calculation. 
Table 13 shows the total estimated number of takes for each species by 
Level A harassment and Level B harassment for individual and concurrent 
activities as well as estimated take as a percent of stock abundance. 
Estimated take by activity type for individual and concurrent equipment 
use for each species is shown in Tables 6-12 through 6-17 in the 
application. OMAO is requesting take by Level A harassment of 4 species 
(harbor porpoise, harbor seal, gray seal, and harp seal) incidental to 
construction activities using one equipment type. In addition, OMAO is 
requesting one take of harbor seals by Level A harassment during 
concurrent use of a DTH mono-hammer and two vibratory hammers for 
installation of 36'' shafts for the small boat floating dock.
    To account for group size, OMAO conservatively increased the 
estimated take by Level B harassment from 9 to 16 Atlantic white-sided 
dolphins, as the calculated take was less than the documented average 
group size (NUWC, 2017). NMFS agrees with this approach, and is 
proposing to authorize 16 takes by Level B harassment of Atlantic 
white-sided dolphins. The species density for the hooded seal was too 
low to result in any calculated estimated takes. In order to be 
conservative, OMAO requested, and NMFS is proposing to authorize, 1 
take by Level B harassment of hooded seals for each month of 
construction activity when this species may occur in the project area. 
Hooded seals may occur in the project area from January through May 
which is a total of 5 months. Therefore, OMAO is requesting, and NMFS 
is proposing to authorize, 5 takes by Level B harassment of hooded 
seals for individual construction activities and 5 takes by Level B 
harassment of hooded seals for concurrent construction activities for a 
total of 10 takes by Level B harassment of hooded seals.

                  Table 13--Total Estimated Take by Level A harassment and Level B Harassment for Individual and Concurrent Activities
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                               Individual activities           Concurrent activities
                                                         ----------------------------------------------------------------      Total
                         Species                              Level A         Level B         Level A         Level B        requested      % of stock
                                                            harassment      harassment      harassment      harassment         take
--------------------------------------------------------------------------------------------------------------------------------------------------------
Atlantic white-sided dolphin............................               0               6               0               3          16 \1\             0.2
Short-beaked common dolphin.............................               0              26               0              13              39             0.2
Harbor Porpoise.........................................               2              27               0              13              42           0.044
Harbor Seal.............................................              55           1,478               1             589           2,123            3.46
Gray Seal...............................................              11             312               0             125             448            1.64
Harp Seal...............................................               4             117               0              47             168           0.002
Hooded Seal.............................................               0           \2\ 5               0           \2\ 5              10           0.002
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Requested take has been increased to mean group size (NUWC, 2017). Mean group size was not used for those take estimates that exceeded the mean
  group size.
\2\ OMAO is conservatively requesting 1 take by Level B harassment of hooded seal per month of construction when this species may occur in the project
  area (January through May).

Proposed Mitigation

    In order to issue an IHA under section 101(a)(5)(D) of the MMPA, 
NMFS must set forth the permissible methods of taking pursuant to the 
activity, and other means of effecting the least practicable impact on 
the species or stock and its habitat, paying particular attention to 
rookeries, mating grounds, and areas of similar significance, and on 
the availability of the species or stock for taking for certain 
subsistence uses (latter not applicable for this action). NMFS 
regulations require applicants for incidental take authorizations to 
include information about the availability and feasibility (economic 
and technological) of equipment, methods, and manner of conducting the 
activity or other means of effecting the least practicable adverse 
impact upon the affected species or stocks, and their habitat (50 CFR 
216.104(a)(11)).
    In evaluating how mitigation may or may not be appropriate to 
ensure the least practicable adverse impact on species or stocks and 
their habitat, as well as subsistence uses where applicable, NMFS 
considers two primary factors:
    (1) The manner in which, and the degree to which, the successful 
implementation of the measure(s) is expected to reduce impacts to 
marine mammals, marine mammal species or stocks, and their habitat. 
This considers the nature of the potential adverse impact being 
mitigated (likelihood, scope, range). It further considers the 
likelihood that the measure will be effective if implemented 
(probability of accomplishing the mitigating result if implemented as 
planned), the likelihood of effective implementation (probability 
implemented as planned), and;
    (2) The practicability of the measures for applicant 
implementation, which may consider such things as cost and impact on 
operations.
    NMFS proposes the following mitigation measures be implemented for 
OMAO's pile installation and removal activities.

Shutdown Zones

    OMAO will establish shutdown zones for all pile driving activities. 
The purpose of a shutdown zone is generally to define an area within 
which shutdown of the activity would occur upon sighting of a marine 
mammal (or in anticipation of an animal entering the defined area). 
Shutdown zones would be based upon the Level A harassment zone for each 
pile size/type and driving method, as shown in Table 14. If the

[[Page 66156]]

Level A harassment zone is too large to monitor, the shutdown zone 
would be limited to a radial distance of 200 m from the acoustic source 
(86 FR 71162, December 15, 2021; 87 FR 19886, April 6, 2022). For 
example, the largest Level A harassment zone for high-frequency 
cetaceans extends approximately 2,444,5 m from the source during DTH 
mono-hammer excavation while installing the 36-in steel shafts for the 
small boat floating dock (Table 7). OMAO plans to maintain maximum 
shutdown zone of 200 m for that activity, consistent with prior 
projects in the area (87 FR 11860, March 2, 2022).
    A minimum shutdown zone of 10 m would be applied for all in-water 
construction activities if the Level A harassment zone is less than 10 
m (i.e., vibratory pile driving, drilling). The 10 m shutdown zone 
would also serve to protect marine mammals from collisions with project 
vessels during pile driving and other construction activities, such as 
barge positioning or drilling. If an activity is delayed or halted due 
to the presence of a marine mammal, the activity may not commence or 
resume until either the animal has voluntarily exited and been visually 
confirmed beyond the shutdown zone indicated in Table 14 or 15 minutes 
have passed without re-detection of the animal. Construction activities 
must be halted upon observation of a species for which incidental take 
is not authorized or a species for which incidental take has been 
authorized but the authorized number of takes has been met entering or 
within the harassment zone.
    If a marine mammal enters the Level B harassment zone, in-water 
work would proceed and PSOs would document the marine mammal's presence 
and behavior.

                        Table 14--Shutdown Zones and Level B Harassment Zones by Activity
----------------------------------------------------------------------------------------------------------------
                                                                  Shutdown zone (m)          Level B harassment
                                                          --------------------------------        zone (m)
          Pile type/size                Driving method                                    ----------------------
                                                              Cetaceans       Pinnipeds      All marine mammals
----------------------------------------------------------------------------------------------------------------
12'' steel pipe...................  Vibratory extraction.              10              10  2,600.
12'' timber.......................  Vibratory extraction.              15              10  3,500.
16'' steel pipe...................  Vibratory install/                 20              10  6,400.
                                     extract.
18'' steel pipe...................  Impact install.......         \1\ 200         \1\ 200  640.
                                    Vibratory install....              30              15  6,400.
                                    DTH Mono-hammer......         \1\ 200         \1\ 200  Maximum harassment
                                                                                            zone.\2\
                                    Rotary drilling 18''               10              10  1,900.
                                     holes.
Z26-700 steel sheets..............  Vibratory install....              15              10  2,600.
30'' steel pipe...................  Impact install.......         \1\ 200         \1\ 200  2,600.
                                    Vibratory install....              55              25  Maximum harassment
                                                                                            zone.\2\
30'' steel pipe...................  Rotary drilling......              10              10  1,900.
36'' steel pipe...................  Impact install.......         \1\ 200         \1\ 200  3,400.
                                    Vibratory install....              90              40  Maximum harassment
                                                                                            zone \2\
36'' shafts.......................  DTH Mono-hammer......         \1\ 200         \1\ 200  Maximum harassment
                                                                                            zone.\2\
----------------------------------------------------------------------------------------------------------------
\1\ Distance to shutdown zone distances implemented for other similar projects in the region (NAVFAC, 2019).
\2\ Harassment zone would be truncated due to the presence of intersecting land masses and would encompass a
  maximum area of 3.31 km\2\.

Protected Species Observers

    The placement of protected species observers (PSOs) during all 
construction activities (described in the Proposed Monitoring and 
Reporting section) would ensure that the entire shutdown zone is 
visible. Should environmental conditions deteriorate such that the 
entire shutdown zone would not be visible (e.g., fog, heavy rain), pile 
driving would be delayed until the PSO is confident marine mammals 
within the shutdown zone could be detected.

Monitoring for Level A Harassment and Level B Harassment

    PSOs would monitor the full shutdown zones and the remaining Level 
A harassment and the Level B harassment zones to the extent 
practicable. Monitoring zones provide utility for observing by 
establishing monitoring protocols for areas adjacent to the shutdown 
zones. Monitoring zones enable observers to be aware of and communicate 
the presence of marine mammals in the project areas outside the 
shutdown zones and thus prepare for a potential cessation of activity 
should the animal enter the shutdown zone.

Pre-Activity Monitoring

    Prior to the start of daily in-water construction activity, or 
whenever a break in pile driving of 30 minutes or longer occurs, PSOs 
would observe the shutdown, Level A harassment, and Level B harassment 
for a period of 30 minutes. Pile driving may commence following 30 
minutes of observation when the determination is made that the shutdown 
zones are clear of marine mammals. If a marine mammal is observed 
within the shutdown zones listed in Table 14, construction activity 
would be delayed until the animal has voluntarily exited and been 
visually confirmed beyond the shutdown zone indicated in Table 14 or 
has not been observed for 15 minutes. When a marine mammal for which 
Level B harassment take is authorized is present in the Level B 
harassment zone, activities would begin and Level B harassment take 
would be recorded. A determination that the shutdown zone is clear must 
be made during a period of good visibility (i.e., the entire shutdown 
zone and surrounding waters are visible). If the shutdown zone is 
obscured by fog or poor lighting conditions, in-water construction 
activity would not be initiated until the entire shutdown zone is 
visible.

Soft-Start

    Soft-start procedures are used to provide additional protection to 
marine mammals by providing warning and/or giving marine mammals a 
chance to leave the area prior to the hammer operating at full 
capacity. For impact pile driving, contractors would be required to 
provide an initial set of three strikes from the hammer at reduced 
energy, followed by a 30-second waiting period, then two subsequent 
reduced-energy strike sets. Soft start would be implemented at the 
start of each day's impact pile driving and at any time following 
cessation of impact pile driving for a period of 30 minutes or longer.
    Based on our evaluation of the applicant's proposed measures, NMFS 
has preliminarily determined that the

[[Page 66157]]

proposed mitigation measures provide the means of effecting the least 
practicable impact on the affected species or stocks and their habitat, 
paying particular attention to rookeries, mating grounds, and areas of 
similar significance.

Proposed Monitoring and Reporting

    In order to issue an IHA for an activity, section 101(a)(5)(D) of 
the MMPA states that NMFS must set forth requirements pertaining to the 
monitoring and reporting of such taking. The MMPA implementing 
regulations at 50 CFR 216.104(a)(13) indicate that requests for 
authorizations 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 while 
conducting the activities. Effective reporting is critical both to 
compliance as well as ensuring that the most value is obtained from the 
required monitoring.
    Monitoring and reporting requirements prescribed by NMFS should 
contribute to improved understanding of one or more of the following:
     Occurrence of marine mammal species or stocks in the area 
in which take is anticipated (e.g., presence, abundance, distribution, 
density);
     Nature, scope, or context of likely marine mammal exposure 
to potential stressors/impacts (individual or cumulative, acute or 
chronic), through better understanding of: (1) action or environment 
(e.g., source characterization, propagation, ambient noise); (2) 
affected species (e.g., life history, dive patterns); (3) co-occurrence 
of marine mammal species with the action; or (4) biological or 
behavioral context of exposure (e.g., age, calving or feeding areas);
     Individual marine mammal responses (behavioral or 
physiological) to acoustic stressors (acute, chronic, or cumulative), 
other stressors, or cumulative impacts from multiple stressors;
     How anticipated responses to stressors impact either: (1) 
long-term fitness and survival of individual marine mammals; or (2) 
populations, species, or stocks;
     Effects on marine mammal habitat (e.g., marine mammal prey 
species, acoustic habitat, or other important physical components of 
marine mammal habitat); and,
     Mitigation and monitoring effectiveness.

Visual Monitoring

    Marine mammal monitoring during in-water construction activities 
would be conducted by PSOs meeting NMFS' standards and in a manner 
consistent with the following:
     Independent PSOs (i.e., employees of the entity conducting 
construction activities may not serve as PSOs) who have no other 
assigned tasks during monitoring periods would be used;
     At least one PSO would have prior experience performing 
the duties of a PSO during construction activity pursuant to a NMFS-
issued incidental take authorization;
     Other PSOs may substitute education (degree in biological 
science or related field) or training for experience; and
     Where a team of three or more PSOs is required, a lead 
observer or monitoring coordinator would be designated. The lead 
observer would be required to have prior experience working as a marine 
mammal observer during construction.
    PSOs would have the following additional qualifications:
     Ability to conduct field observations and collect data 
according to assigned protocols;
     Experience or training in the field identification of 
marine mammals, including the identification of behaviors;
     Sufficient training, orientation, or experience with the 
construction operation to provide for personal safety during 
observations;
     Writing skills sufficient to prepare a report of 
observations including but not limited to the number and species of 
marine mammals observed; dates and times when in-water construction 
activities were conducted; dates, times, and reason for implementation 
of mitigation (or why mitigation was not implemented when required); 
and marine mammal behavior; and
     Ability to communicate orally, by radio or in person, with 
project personnel to provide real-time information on marine mammals 
observed in the area as necessary.
    Visual monitoring would be conducted by a minimum of two trained 
PSOs positioned at suitable vantage points. Any activity for which the 
Level B harassment isopleth would exceed 1,900 meters would require a 
minimum of three PSOs to effectively monitor the entire Level B 
harassment zone. PSOs would likely be located on Gould Island South, 
Gould Island Pier, Coddington Point, Bishop Rock, Breakwater, or Taylor 
Point as shown in Figure 11-1 in the application. All PSOs would have 
access to high-quality binoculars, range finders to monitor distances, 
and a compass to record bearing to animals as well as radios or cells 
phones for maintaining contact with work crews.
    Monitoring would be conducted 30 minutes before, during, and 30 
minutes after all in water construction activities. In addition, PSOs 
would record all incidents of marine mammal occurrence, regardless of 
distance from activity, and would document any behavioral reactions in 
concert with distance from piles being driven or removed. Pile driving 
activities include the time to install or remove a single pile or 
series of piles, as long as the time elapsed between uses of the pile 
driving equipment is no more than 30 minutes.
    OMAO and the Navy shall conduct briefings between construction 
supervisors and crews, PSOs, OMAO and Navy staff prior to the start of 
all pile driving activities and when new personnel join the work. These 
briefings would explain responsibilities, communication procedures, 
marine mammal monitoring protocol, and operational procedures.

Hydro-Acoustic Monitoring

    OMAO would implement in situ acoustic monitoring efforts to measure 
SPLs from in-water construction activities by collecting and evaluating 
acoustic sound recording levels during activities. Stationary 
hydrophones would be placed 33 ft (10 m) from the noise source, in 
accordance with NMFS' most recent guidance for the collection of source 
levels. If there is the potential for Level A harassment, a second 
monitoring location would be set up at an intermediate distance between 
cetacean/phocid shutdown zones and Level A harassment zones. 
Hydrophones would be deployed with a static line from a stationary 
vessel. Locations of hydro-acoustic recordings would be collected via 
GPS. A depth sounder and/or weighted tape measure would be used to 
determine the depth of the water. The hydrophone would be attached to a 
weighted nylon cord or chain to maintain a constant depth and distance 
from the pile area. The nylon cord or chain would be attached to a 
float or tied to a static line.
    Each hydrophone would be calibrated at the start of each action and 
would be checked frequently to the applicable standards of the 
hydrophone manufacturer. Environmental data would be collected, 
including but not limited to, the following: wind speed and direction, 
air temperature, humidity, surface water temperature, water depth, wave 
height, weather conditions, and other factors that could

[[Page 66158]]

contribute to influencing the airborne and underwater sound levels 
(e.g., aircraft, boats, etc.). The chief inspector would supply the 
acoustics specialist with the substrate composition, hammer or drill 
model and size, hammer or drill energy settings and any changes to 
those settings during the piles being monitored, depth of the pile 
being driven or shaft excavated, and blows per foot for the piles 
monitored. For acoustically monitored piles and shafts, data from the 
monitoring locations would be post-processed to obtain the following 
sound measures:
     Maximum peak pressure level recorded for all the strikes 
associated with each pile or shaft, expressed in dB re 1 [mu]Pa. For 
pile driving and DTH mono-hammer excavation, this maximum value would 
originate from the phase of pile driving/drilling during which hammer/
drill energy was also at maximum (referred to as Level 4);
     From all the strikes associated with each pile occurring 
during the Level 4 phase these additional measures would be made:
    (1) mean, median, minimum, and maximum RMS pressure level in [dB re 
1 [mu]Pa];
    (2) mean duration of a pile strike (based on the 90 percent energy 
criterion);
    (3) number of hammer strikes;
    (4) mean, median, minimum, and maximum single strike SEL in [dB re 
[mu]Pa2 s];
     Cumulative SEL as defined by the mean single strike SEL + 
10*log10 (number of hammer strikes) in [dB re [mu]Pa2 s];
     Median integration time used to calculate SPL RMS;
     A frequency spectrum (pressure spectral density) in [dB re 
[mu]Pa2 per Hertz {Hz{time} ] based on the average of up to eight 
successive strikes with similar sound. Spectral resolution would be 1 
Hz, and the spectrum would cover nominal range from 7 Hz to 20 kHz;
     Finally, the cumulative SEL would be computed from all the 
strikes associated with each pile occurring during all phases, i.e., 
soft-start, Level 1 to Level 4. This measure is defined as the sum of 
all single strike SEL values. The sum is taken of the antilog, with 
log10 taken of result to express in [dB re [mu]Pa2 s].
    Hydro-acoustic monitoring would be conducted for at least 10% and 
up to 10 of each different pile type for each method of installation as 
shown in Table 13-1 in the application All acoustic data would be 
analyzed after the project period for pile driving, rotary drilling, 
and DTH mono-hammer excavation events to confirm SPLs and rate of 
transmission loss for each construction activity.

Reporting

    OMAO would submit a draft marine mammal monitoring report to NMFS 
within 90 days after the completion of pile driving activities, or 60 
days prior to a requested date of issuance of any future IHAs for the 
project, or other projects at the same location, whichever comes first. 
The marine mammal monitoring report would include an overall 
description of work completed, a narrative regarding marine mammal 
sightings, and associated PSO data sheets. Specifically, the report 
would include:
     Dates and times (begin and end) of all marine mammal 
monitoring;
     Construction activities occurring during each daily 
observation period, including:
    (1) The number and type of piles that were driven and the method 
(e.g., impact, vibratory, down-the-hole, etc.);
    (2) Total duration of time for each pile (vibratory driving) number 
of strikes for each pile (impact driving); and
    (3) For down-the-hole drilling, duration of operation for both 
impulsive and non-pulse components.
     PSO locations during marine mammal monitoring; and
     Environmental conditions during monitoring periods (at 
beginning and end of PSO shift and whenever conditions change 
significantly), including Beaufort sea state and any other relevant 
weather conditions including cloud cover, fog, sun glare, and overall 
visibility to the horizon, and estimated observable distance.
    For each observation of a marine mammal, the following would be 
reported:
     Name of PSO who sighted the animal(s) and PSO location and 
activity at time of sighting;
     Time of sighting;
     Identification of the animal(s) (e.g., genus/species, 
lowest possible taxonomic level, or unidentified), PSO confidence in 
identification, and the composition of the group if there is a mix of 
species;
     Distance and location of each observed marine mammal 
relative to the pile being driven or hole being drilled for each 
sighting;
     Estimated number of animals (min/max/best estimate);
     Estimated number of animals by cohort (adults, juveniles, 
neonates, group composition, etc.);
     Animal's closest point of approach and amount of time 
spent in harassment zone;
     Description of any marine mammal behavioral observations 
(e.g., observed behaviors such as feeding or traveling), including an 
assessment of behavioral responses thought to have resulted from the 
activity (e.g., no response or changes in behavioral state such as 
ceasing feeding, changing direction, flushing, or breaching);
     Number of marine mammals detected within the harassment 
zones, by species; and
     Detailed information about implementation of any 
mitigation (e.g., shutdowns and delays), a description of specified 
actions that ensued, and resulting changes in behavior of the 
animal(s), if any.
    If no comments are received from NMFS within 30 days, the draft 
report would constitute the final reports. If comments are received, a 
final report addressing NMFS' comments would be required to be 
submitted within 30 days after receipt of comments. All PSO datasheets 
and/or raw sighting data would be submitted with the draft marine 
mammal report.
    In the event that personnel involved in the construction activities 
discover an injured or dead marine mammal, OMAO would report the 
incident to the Office of Protected Resources (OPR) 
([email protected]ov), NMFS and to the Northeast Region 
(GARFO) regional stranding coordinator as soon as feasible. If the 
death or injury was clearly caused by the specified activity, OMAO 
would immediately cease the specified activities until NMFS is able to 
review the circumstances of the incident and determine what, if any, 
additional measures are appropriate to ensure compliance with the terms 
of the IHAs. OMAO would not resume their activities until notified by 
NMFS.
    The report would include the following information:
    1. Time, date, and location (latitude/longitude) of the first 
discovery (and updated location information if known and applicable);
    2. Species identification (if known) or description of the 
animal(s) involved;
    3. Condition of the animal(s) (including carcass condition if the 
animal is dead);
    4. Observed behaviors of the animal(s), if alive;
    5. If available, photographs or video footage of the animal(s); and
    6. General circumstances under which the animal was discovered.
    OMAO would also provide a hydro-acoustic monitoring report based 
upon hydro-acoustic monitoring conducted during construction 
activities. The hydro-acoustic monitoring report would include:

[[Page 66159]]

     Hydrophone equipment and methods: recording device, 
sampling rate, distance (meter) from the pile where recordings were 
made; depth of water and recording device(s);
     Type and size of pile being driven, substrate type, method 
of driving during recordings (e.g., hammer model and energy), and total 
pile driving duration;
     Whether a sound attenuation device is used and, if so, a 
detailed description of the device used and the duration of its use per 
pile;
     For impact pile driving and/or DTH mono-hammer excavation 
(per pile): Number of strikes and strike rate; depth of substrate to 
penetrate; pulse duration and mean, median, and maximum sound levels 
(dB re: 1 [mu]Pa): root mean square sound pressure level 
(SPLrms); cumulative sound exposure level 
(SELcum), peak sound pressure level (SPLpeak), 
and single-strike sound exposure level (SELs-s);
     For vibratory driving/removal and/or DTH mono-hammer 
excavation (per pile): Duration of driving per pile; mean, median, and 
maximum sound levels (dB re: 1 [mu]Pa): root mean square sound pressure 
level (SPLrms), cumulative sound exposure level 
(SELcum) (and timeframe over which the sound is averaged);
     One-third octave band spectrum and power spectral density 
plot; and
     General daily site conditions, including date and time of 
activities, water conditions (e.g., sea state, tidal state), and 
weather conditions (e.g., percent cover, visibility.

Negligible Impact Analysis and Determination

    NMFS has defined negligible impact 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 (50 CFR 216.103). A 
negligible impact finding is based on the lack of likely adverse 
effects on annual rates of recruitment or survival (i.e., population-
level effects). An estimate of the number of takes alone is not enough 
information on which to base an impact determination. In addition to 
considering estimates of the number of marine mammals that might be 
``taken'' through harassment, NMFS considers other factors, such as the 
likely nature of any impacts or responses (e.g., intensity, duration), 
the context of any impacts or responses (e.g., critical reproductive 
time or location, foraging impacts affecting energetics), as well as 
effects on habitat, and the likely effectiveness of the mitigation. We 
also assess the number, intensity, and context of estimated takes by 
evaluating this information relative to population status. Consistent 
with the 1989 preamble for NMFS' implementing regulations (54 FR 40338, 
September 29, 1989), the impacts from other past and ongoing 
anthropogenic activities are incorporated into this analysis via their 
impacts on the baseline (e.g., as reflected in the regulatory status of 
the species, population size and growth rate where known, ongoing 
sources of human-caused mortality, or ambient noise levels).
    To avoid repetition, the majority of our analysis applies to all 
the species listed in Table 3, given that many of the anticipated 
effects of this project on different marine mammal stocks are expected 
to be relatively similar in nature. Where there are meaningful 
differences between species or stocks, or groups of species, in 
anticipated individual responses to activities, impact of expected take 
on the population due to differences in population status, or impacts 
on habitat, they are described independently in the analysis below.
    Pile driving activities associated with the OMAO vessel relocation 
project have the potential to disturb or displace marine mammals. 
Specifically, the project activities may result in take, in the form of 
Level B harassment, and for harbor porpoise, harbor seal, gray seal, 
and harp seal, Level A harassment, from underwater sounds generated 
from pile driving and removal, DTH, and rotary drilling. Potential 
takes could occur if individuals are present in zones ensonified above 
the thresholds for Level B harassment, identified above, when these 
activities are underway.
    No serious injury or mortality would be expected, even in the 
absence of required mitigation measures, given the nature of the 
activities. Further, no take by Level A harassment is anticipated for 
Atlantic white-sided dolphins, short-beaked common dolphins, and harp 
seals due to the application of planned mitigation measures, such as 
shutdown zones that encompass the Level A harassment zones for these 
species. The potential for harassment would be minimized through the 
construction method and the implementation of the planned mitigation 
measures (see Proposed Mitigation section).
    Take by Level A harassment is proposed for 4 species (harbor 
porpoise, harbor seal, gray seal, and harp seal) as the Level A 
harassment zones exceed the size of the shutdown zones for specific 
construction scenarios. Therefore, there is the possibility that an 
animal could enter a Level A harassment zone without being detected, 
and remain within that zone for a duration long enough to incur PTS. 
Any take by Level A harassment is expected to arise from, at most, a 
small degree of PTS (i.e., minor degradation of hearing capabilities 
within regions of hearing that align most completely with the energy 
produced by impact pile driving such as the low-frequency region below 
2 kHz), not severe hearing impairment or impairment within the ranges 
of greatest hearing sensitivity. Animals would need to be exposed to 
higher levels and/or longer duration than are expected to occur here in 
order to incur any more than a small degree of PTS.
    Further, the amount of take proposed for authorization by Level A 
harassment is very low for all marine mammal stocks and species. For 
three species, Atlantic white-sided dolphin, short-beaked common 
dolphin, and harp seal, NMFS anticipates and proposes to authorize no 
Level A harassment take over the duration of OMAO's planned activities; 
for the other four stocks, NMFS proposes to authorize no more than 56 
takes by Level A harassment for any stock. If hearing impairment 
occurs, it is most likely that the affected animal would lose only a 
few decibels in its hearing sensitivity. Due to the small degree 
anticipated, any PTS potential incurred would not be expected to affect 
the reproductive success or survival of any individuals, much less 
result in adverse impacts on the species or stock.
    Additionally, some subset of the individuals that are behaviorally 
harassed could also simultaneously incur some small degree of TTS for a 
short duration of time. However, since the hearing sensitivity of 
individuals that incur TTS is expected to recover completely within 
minutes to hours, it is unlikely that the brief hearing impairment 
would affect the individual's long-term ability to forage and 
communicate with conspecifics, and would therefore not likely impact 
reproduction or survival of any individual marine mammal, let alone 
adversely affect rates of recruitment or survival of the species or 
stock.
    As described above, NMFS expects that marine mammals would likely 
move away from an aversive stimulus, especially at levels that would be 
expected to result in PTS, given sufficient notice through use of soft 
start. OMAO would also shut down pile driving activities if marine 
mammals enter the shutdown zones (see Table 14) further minimizing the 
likelihood and degree of PTS that would be incurred.
    Effects on individuals that are taken by Level B harassment in the 
form of

[[Page 66160]]

behavioral disruption, on the basis of reports in the literature as 
well as monitoring from other similar activities, would likely be 
limited to reactions such as avoidance, increased swimming speeds, 
increased surfacing time, or decreased foraging (if such activity were 
occurring) (e.g., Thorson and Reyff 2006). Most likely, individuals 
would simply move away from the sound source and temporarily avoid the 
area where pile driving is occurring. If sound produced by project 
activities is sufficiently disturbing, animals are likely to simply 
avoid the area while the activities are occurring. We expect that any 
avoidance of the project areas by marine mammals would be temporary in 
nature and that any marine mammals that avoid the project areas during 
construction would not be permanently displaced. Short-term avoidance 
of the project areas and energetic impacts of interrupted foraging or 
other important behaviors is unlikely to affect the reproduction or 
survival of individual marine mammals, and the effects of behavioral 
disturbance on individuals is not likely to accrue in a manner that 
would affect the rates of recruitment or survival of any affected 
stock.
    Since June 2022, an Unusual Mortality Event (UME) has been declared 
for Northeast pinnipeds in which elevated numbers of sick and dead 
harbor seals and gray seals have been documented along the southern and 
central coast of Maine (NOAA Fisheries, 2022). As of October 18, 2022, 
the date of writing of this notice, 22 grays seals and 230 harbor seals 
have stranded. However, we do not expect takes that may be authorized 
under this rule to exacerbate or compound upon these ongoing UMEs. As 
noted previously, no injury, serious injury, or mortality is expected 
or will be authorized, and takes of harbor seal and gray seal will be 
reduced to the level of least practicable adverse impact through the 
incorporation of the required mitigation measures. For the WNA stock of 
gray seal, the estimated U.S. stock abundance is 27,300 animals 
(estimated 424,300 animals in the Canadian portion of the stock). Given 
that only 448 takes may be authorized for this stock, we do not expect 
this authorization to exacerbate or compound upon the ongoing UME. For 
the WNA stock of harbor seals, the estimated abundance is 61,336 
individuals. The estimated M/SI for this stock (339) is well below the 
PBR (1,729) (Hayes et al., 2020). As such, the takes of harbor seal 
that may be authorized are not expected to exacerbate or compound upon 
the ongoing UME.
    The project is also not expected to have significant adverse 
effects on affected marine mammals' habitats. No ESA-designated 
critical habitat or biologically important areas (BIAs) are located 
within the project area. The project activities would not modify 
existing marine mammal habitat for a significant amount of time. The 
activities may cause a low level of turbidity in the water column and 
some fish may leave the area of disturbance, thus temporarily impacting 
marine mammals' foraging opportunities in a limited portion of the 
foraging range; but, because of the short duration of the activities 
and the relatively small area of the habitat that may be affected (with 
no known particular importance to marine mammals), the impacts to 
marine mammal habitat are not expected to cause significant or long-
term negative consequences. Seasonal nearshore marine mammal surveys 
were conducted at NAVSTA Newport from May 2016 to February 2017, and 
several harbor seal haul outs were identified in Narragansett Bay, but 
no pupping was observed.
    For all species and stocks, take would occur within a limited, 
relatively confined area (Coddington Cove) of the stock's range. Given 
the availability of suitable habitat nearby, any displacement of marine 
mammals from the project areas is not expected to affect marine 
mammals' fitness, survival, and reproduction due to the limited 
geographic area that would be affected in comparison to the much larger 
habitat for marine mammals within Narragansett Bay and outside the bay 
along the Rhode Island coasts. Level A harassment and Level B 
harassment would be reduced to the level of least practicable adverse 
impact to the marine mammal species or stocks and their habitat through 
use of mitigation measures described herein.
    Some individual marine mammals in the project area, such as harbor 
seals, may be present and be subject to repeated exposure to sound from 
pile driving activities on multiple days. However, pile driving and 
extraction is not expected to occur on every day, and these individuals 
would likely return to normal behavior during gaps in pile driving 
activity within each day of construction and in between work days. As 
discussed above, there is similar transit and haulout habitat available 
for marine mammals within and outside of the Narragansett Bay along the 
Rhode Island coast, outside of the project area, where individuals 
could temporarily relocate during construction activities to reduce 
exposure to elevated sound levels from the project. Therefore, any 
behavioral effects of repeated or long duration exposures are not 
expected to negatively affect survival or reproductive success of any 
individuals. Thus, even repeated Level B harassment of some small 
subset of an overall stock is unlikely to result in any effects on 
rates of reproduction and survival of the stock.
    In summary and as described above, the following factors primarily 
support our preliminary determination that the impacts resulting from 
this activity are not expected to adversely affect any of the species 
or stocks through effects on annual rates of recruitment or survival:
     No serious injury or mortality is anticipated or proposed 
for authorization;
     No Level A harassment of Atlantic white-sided dolphins, 
short-beaked common dolphins, or harp seals is proposed;
     The small Level A harassment takes of harbor porpoises, 
harbor seals, gray seals, and hooded seals proposed for authorization 
are expected to be of a small degree;
     The intensity of anticipated takes by Level B harassment 
is relatively low for all stocks. Level B harassment would be primarily 
in the form of behavioral disturbance, resulting in avoidance of the 
project areas around where impact or vibratory pile driving is 
occurring, with some low-level TTS that may limit the detection of 
acoustic cues for relatively brief amounts of time in relatively 
confined footprints of the activities;
     Nearby areas of similar habitat value (e.g., transit and 
haulout habitats) within and outside of Narragansett Bay are available 
for marine mammals that may temporarily vacate the project area during 
construction activities;
     The specified activity and associated ensonifed areas do 
not include habitat areas known to be of special significance (BIAs or 
ESA-designated critical habitat);
     Effects on species that serve as prey for marine mammals 
from the activities are expected to be short-term and, therefore, any 
associated impacts on marine mammal feeding are not expected to result 
in significant or long-term consequences for individuals, or to accrue 
to adverse impacts on their populations;
     The ensonified areas are very small relative to the 
overall habitat ranges of all species and stocks, and would not 
adversely affect ESA-designated critical habitat for any species or any 
areas of known biological importance;

[[Page 66161]]

     The lack of anticipated significant or long-term negative 
effects to marine mammal habitat; and
     The efficacy of the mitigation measures in reducing the 
effects of the specified activities on all species and stocks.
    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 proposed monitoring and 
mitigation measures, NMFS preliminarily finds that the total marine 
mammal take from the proposed activity would have a negligible impact 
on all affected marine mammal species or stocks.

Small Numbers

    As noted above, only small numbers of incidental take may be 
authorized under sections 101(a)(5)(A) and (D) of the MMPA for 
specified activities other than military readiness activities. The MMPA 
does not define small numbers and so, in practice, where estimated 
numbers are available, NMFS compares the number of individuals taken to 
the most appropriate estimation of abundance of the relevant species or 
stock in our determination of whether an authorization is limited to 
small numbers of marine mammals. When the predicted number of 
individuals to be taken is fewer than one-third of the species or stock 
abundance, the take is considered to be of small numbers. Additionally, 
other qualitative factors may be considered in the analysis, such as 
the temporal or spatial scale of the activities.
    The instances of take NMFS proposes to authorize is below one-third 
of the estimated stock abundance for all impacted stocks (Table 13). 
(In fact, take of individuals is less than 4% of the abundance for all 
affected stocks.) The number of animals that we expect to authorize to 
be taken would be considered small relative to the relevant stocks or 
populations, even if each estimated take occurred to a new individual. 
Furthermore, these takes are likely to only occur within a small 
portion of the each stock's range and the likelihood that each take 
would occur to a new individual is low.
    Based on the analysis contained herein of the proposed activity 
(including the proposed mitigation and monitoring measures) and the 
anticipated take of marine mammals, NMFS preliminarily finds that small 
numbers of marine mammals would be taken relative to the population 
size of the affected species or stocks.

Unmitigable Adverse Impact Analysis and Determination

    There are no relevant subsistence uses of the affected marine 
mammal stocks or species implicated by this action. Therefore, NMFS has 
determined that the total taking of affected species or stocks would 
not have an unmitigable adverse impact on the availability of such 
species or stocks for taking for subsistence purposes.

Endangered Species Act

    Section 7(a)(2) of the Endangered Species Act of 1973 (ESA; 16 
U.S.C. 1531 et seq.) requires that each Federal agency insure that any 
action it authorizes, funds, or carries out is not likely to jeopardize 
the continued existence of any endangered or threatened species or 
result in the destruction or adverse modification of designated 
critical habitat. To ensure ESA compliance for the issuance of IHAs, 
NMFS consults internally whenever we propose to authorize take for 
endangered or threatened species.
    No incidental take of ESA-listed species is proposed for 
authorization or expected to result from this activity. Therefore, NMFS 
has determined that formal consultation under section 7 of the ESA is 
not required for this action.

Proposed Authorization

    As a result of these preliminary determinations, NMFS proposes to 
issue an IHA to OMAO for conducting pile driving activities incidental 
to the NOAA vessel relocation project at Naval Station Newport, RI from 
February 1, 2024 to January 31, 2025, provided the previously mentioned 
mitigation, monitoring, and reporting requirements are incorporated. A 
draft of the proposed IHA can be found at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities.

Request for Public Comments

    We request comment on our analyses, the proposed authorization, and 
any other aspect of this notice of proposed IHA for the proposed pile 
driving activities. We also request comment on the potential renewal of 
this proposed IHA as described in the paragraph below. Please include 
with your comments any supporting data or literature citations to help 
inform decisions on the request for this IHA or a subsequent renewal 
IHA.
    On a case-by-case basis, NMFS may issue a one-time, one-year 
renewal IHA following notice to the public providing an additional 15 
days for public comments when (1) up to another year of identical or 
nearly identical activities as described in the Description of Proposed 
Activities section of this notice is planned or (2) the activities as 
described in the Description of Proposed Activities section of this 
notice would not be completed by the time the IHA expires and a renewal 
would allow for completion of the activities beyond that described in 
the Dates and Duration section of this notice, provided all of the 
following conditions are met:
     A request for renewal is received no later than 60 days 
prior to the needed renewal IHA effective date (recognizing that the 
renewal IHA expiration date cannot extend beyond one year from 
expiration of the initial IHA).
     The request for renewal must include the following:
    (1) An explanation that the activities to be conducted under the 
requested renewal IHA are identical to the activities analyzed under 
the initial IHA, are a subset of the activities, or include changes so 
minor (e.g., reduction in pile size) that the changes do not affect the 
previous analyses, mitigation and monitoring requirements, or take 
estimates (with the exception of reducing the type or amount of take).
    (2) A preliminary monitoring report showing the results of the 
required monitoring to date and an explanation showing that the 
monitoring results do not indicate impacts of a scale or nature not 
previously analyzed or authorized.
    Upon review of the request for renewal, the status of the affected 
species or stocks, and any other pertinent information, NMFS determines 
that there are no more than minor changes in the activities, the 
mitigation and monitoring measures will remain the same and 
appropriate, and the findings in the initial IHA remain valid.

    Dated: October 27, 2022.
Kimberly Damon-Randall,
Director, Office of Protected Resources, National Marine Fisheries 
Service.
[FR Doc. 2022-23775 Filed 11-1-22; 8:45 am]
BILLING CODE 3510-22-P