Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to U.S. Navy Construction of the Multifunctional Expansion of Dry Dock 1 at Portsmouth Naval Shipyard, Kittery, Maine, 11860-11889 [2022-04406]

Agencies

• DEPARTMENT OF COMMERCE
• National Oceanic and Atmospheric Administration

[Federal Register Volume 87, Number 41 (Wednesday, March 2, 2022)]
[Notices]
[Pages 11860-11889]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2022-04406]



[[Page 11859]]

Vol. 87

Wednesday,

No. 41

March 2, 2022

Part II





Department of Commerce





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National Oceanic and Atmospheric Administration





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Takes of Marine Mammals Incidental to Specified Activities; Taking 
Marine Mammals Incidental to U.S. Navy Construction of the 
Multifunctional Expansion of Dry Dock 1 at Portsmouth Naval Shipyard, 
Kittery, Maine; Notice

Federal Register / Vol. 87 , No. 41 / Wednesday, March 2, 2022 / 
Notices

[[Page 11860]]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

[RTID 0648-XB652]


Takes of Marine Mammals Incidental to Specified Activities; 
Taking Marine Mammals Incidental to U.S. Navy Construction of the 
Multifunctional Expansion of Dry Dock 1 at Portsmouth Naval Shipyard, 
Kittery, Maine

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

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

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SUMMARY: NMFS has received a request from the U.S. Navy (Navy) for 
authorization to take marine mammals incidental to construction 
activities associated with the multifunctional expansion of Dry Dock 1 
at Portsmouth Naval Shipyard in Kittery, Maine. 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 
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 March 
31, 2022.

ADDRESSES: Comments should be addressed to Jolie Harrison, Chief, 
Permits and Conservation Division, Office of Protected Resources, 
National Marine Fisheries Service. Written comments 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 will 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: Stephanie Egger, 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/permit/incidental-take-authorizations-under-marine-mammal-protection-act. 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 issued or, if the taking is limited to harassment, a notice of a 
proposed incidental take authorization may be 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 such 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 such takings are set forth. The definitions 
of all applicable MMPA statutory terms cited above are included in the 
relevant sections below.

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 (IHA 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 NMFS has 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.
    NMFS 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 September 2, 2021, NMFS received a request from the Navy for an 
IHA to take marine mammals incidental to construction activities 
associated with the multifunctional expansion of Dry Dock 1 project 
(also referred to as P-831) at Portsmouth Naval Shipyard in Kittery, 
Maine. The Navy submitted a revised version of the application on 
December 21, 2021. The application was deemed adequate and complete on 
February 10, 2022. The Navy's request is for take of harbor porpoises, 
harbor seals, gray seals, harp seals, and hooded seals by Level A 
harassment and Level B harassment. Neither the Navy nor NMFS expects 
serious injury or mortality to result from this activity; therefore, an 
IHA is appropriate.
    NMFS previously issued IHAs and renewals to the Navy for waterfront 
improvement work in Portsmouth, in 2017 (81 FR 85525; November 28, 
2016), 2018 (83 FR 3318; January 24, 2018), 2019 (84 FR 24476, May 28, 
2019), a renewal of the 2019 IHA (86 FR 14598; March 17, 2021), and a 
2021 IHA (86 FR 30418; June 8, 2021) As required, the applicant 
provided monitoring reports (available at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities) which confirm that the 
applicant has implemented the required mitigation and monitoring, and 
which also shows that no impacts of a scale or nature not previously 
analyzed or authorized have occurred as a result of the activities 
conducted.
    This proposed IHA would cover 1 year of a larger project for which 
the Navy intends to request a take authorization for subsequent facets 
of the project. The larger overall expansion

[[Page 11861]]

and modification of Dry Dock 1 project involves modification of the 
super flood basin to create two additional dry docking positions (Dry 
Dock 1 North and Dry Dock 1 West) in front of the existing Dry Dock 1 
East. Year 1 construction activities will focus on the preparation of 
the walls and floors of the super flood basin to support the placement 
of the monoliths and the construction of the two dry dock positions. 
The Navy complied with all the requirements (e.g., mitigation, 
monitoring, and reporting) of the previous IHAs they provided for other 
preparatory work related to the Dry Dock 1 project and information 
regarding their monitoring results may be found in the Estimated Take 
section.

Description of Proposed Activity

Overview

    Multifunctional Expansion of Dry Dock 1 (P-381) is one of three 
projects that support the overall expansion and modification of Dry 
Dock 1, located in the western extent of the shipyard. The previous two 
projects, construction of a super flood basin (P-310) and extension of 
portal crane rail and utilities (P-1074) are currently under 
construction. Work associated with P-310 and P-1074 has been and/or is 
being completed under the separate IHAs issued by NMFS. The projects 
have been phased to support Navy mission schedules. P-381 will be 
constructed within the same footprint of the super flood basin over an 
approximated 7-year period. In-water activities are expected to occur 
within the first 5 years, between April 2022 and April 2027. This IHA 
request is for the first year of in-water construction for P-381 
occurring from April 2022 through April 2023. All work beyond year 1 is 
anticipated to be requested in a rulemaking/Letter of Authorization 
(LOA) application submission to NMFS.
    The purpose of the proposed project, Multifunctional Expansion of 
Dry Dock 1 (P-381), is to modify the super flood basin to create two 
additional dry docking positions (Dry Dock 1 North and Dry Dock 1 West) 
in front of the existing Dry Dock 1 East. The super flood basin 
provides the starting point for the P-381 work (see Figure 1-2 of the 
application).
    Year 1 construction activities will focus on the preparation of the 
walls and floors of the super flood basin to support the placement of 
the monoliths and the construction of the two dry dock positions. The 
primary work needed to prepare the super flood basin involves 
structural reinforcement of the existing berths and floor within the 
super flood basin, bedrock removal, and demolition of portions of the 
super flood basin walls. Most of the preparatory work will occur behind 
the existing super flood basin walls that would act as a barrier to 
sound and would contain underwater noise to within a small portion of 
the Piscataqua River (see Figure 1-3 of the application). Construction 
activities that could affect marine mammals are limited to in-water 
pile driving and removal activities, rock hammering, rotary drilling, 
and down-the-hole (DTH) hammering.

Dates and Duration

    The construction activities are anticipated to begin in March 2022 
and proceed to March 2023. In-water construction activities would occur 
for 365 days over a period of approximately 12 consecutive months. All 
in-water work capable of producing noise harmful to marine mammals will 
be limited to daylight hours. Pile driving days are not necessarily 
consecutive and certain activities may occur at the same time, 
decreasing the total number of in-water construction days. The 
contractor could be working in more than one area of the berths at a 
time. It is not possible to predict if and/or how often work will occur 
simultaneously, but it is estimated that overlapping activities would 
permit the work described in Table 1 to be completed within one 
calendar year. Table 1 provides the estimated construction schedule and 
production rates for P-381 Year 1 construction activities. Table 1 
reflects the current pile driving, hammering, and drilling durations 
for activities occurring in Year 1 included in this request for 
incidental take authorization. Vibratory pile driving and extraction is 
assumed to occur during 84 days of Year 1. Impact pile driving will 
occur during 24 days in Year 1. DTH activities would occur for 919 days 
and rotary drilling would occur for 282 days. Rock hammering would 
occur for 252 days. Overlapping activities are estimated to reduce the 
number of construction days by 1,172 days for a total of 365 
construction days.

                                                      Table 1--Pile Driving and Drilling Durations
                                                                 [March 2022-March 2023]
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                                                                                                                                                 Total
              Activity                  Total amount and       Activity component               Method               Daily production rate    production
                                         estimated dates                                                                                         days
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Center Wall--Install Foundation      38 drilled shafts, Mar- Install 102-inch        Rotary Drill...............  1 shaft/day, 1 hour/day...          38
 Support Piles.                       22 to Mar-23.           diameter outer casing.
                                                             Pre-drill 102-inch      Rotary Drill...............  1 shaft/day, 9 hours/day..          38
                                                              diameter socket.
                                                             Remove 102-inch outer   Rotary Drill...............  1 casing/day, 15 minutes/           38
                                                              casing.                                              casing.
                                                             Drill 78-inch diameter  Cluster drill DTH..........  6.5 days/shaft, 10 hours/          247
                                                              shaft.                                               day.
Center Wall--Install Diving Board    18 drilled shafts, Mar- Install 102-inch        Rotary Drill...............  1 shaft/day, 1 hour/day...          18
 Shafts.                              22 to Mar-23.           diameter outer casing.
                                                             Pre-drill 102-inch      Rotary Drill...............  1 shaft/day, 9 hours/day..          18
                                                              diameter socket.
                                                             Remove 102-inch outer   Rotary Drill...............  1 casing/day, 15 minutes/           18
                                                              casing.                                              casing.
                                                             Drill 78-inch diameter  Cluster drill DTH..........  6.5 days/shaft, 10 hours/          117
                                                              shaft.                                               day.
Center Wall--Access Platform         38 drilled shafts, Mar- Install 102-inch        Rotary Drill...............  1 shaft/day, 1 hour/day...          38
 Support.                             22 to Mar-23.           diameter outer casing.
                                                             Pre-drill 102-inch      Rotary Drill...............  1 shaft/day, 9 hours/day..          38
                                                              diameter socket.
                                                             Remove 102-inch outer   Rotary Drill...............  1 casing/day, 15 minutes/           38
                                                              casing.                                              casing.
                                                             Drill 78-inch diameter  Cluster drill DTH..........  3.5 days/shaft, 10 hours/          133
                                                              shaft.                                               day.
Center Wall--Temporary Launching     6 drilled shafts, Mar-  42-inch diameter shaft  Mono-hammer DTH............  1 shaft/day, 10 hours/day.           6
 Piles.                               22 to Apr-22.

[[Page 11862]]

 
Center Wall Tie Downs..............  Install 36 rock         9-inch diameter holes.  Mono-hammer DTH............  2 holes/day, 5 hours/hole.          18
                                      anchors, Mar-22 to
                                      Mar-23.
Center Wall--Access Platform Tie     Install 18 rock         9-inch diameter holes.  Mono-hammer DTH............  2 holes/day, 5 hours/hole.           9
 Downs.                               anchors, Mar-22 to
                                      Mar-23.
Center Wall--Install Tie-In to       16 sheet piles, Mar-22  28-inch wide Z-shaped   Impact with initial          4 piles/day, 5 minutes and         * 4
 Existing West Closure Wall.          to Mar-23\+\.           sheets.                 vibratory set.               300 blows/pile.
Berth 11 End Wall--Install Secant    60 sheet piles, Feb-22  28-inch wide Z-shaped   Impact with initial          8 piles/day, 5 minutes and           8
 Pile Guide Wall.                     to Mar-23.              sheets.                 vibratory set.               300 blows/pile.
Berth 1--Remove Granite Block Quay   610 cy, May-22 to Mar-  Granite block           Hydraulic rock hammering...  2.5 hours/day.............        * 10
 Wall.                                23\+\.                  demolition.
P-310 West Closure Wall--Remove      238 sheet piles, Aug-   18-inch wide flat-      Vibratory extraction.......  4 piles/day, 5 minutes/             60
 Closure Wall.                        22 to Oct-22.           sheets.                                              pile.
P-310 West Closure Wall--Mechanical  985 cy, Nov-22 to Feb-  Excavate bedrock......  Hydraulic rock hammering...  9 hours/day...............          77
 Rock Excavation.                     23.
P-310 West Closure Wall--Mechanical  Drill 500 relief        4-6 inch holes........  Mono-hammer DTH............  25 holes/day, 24 minutes/           20
 Rock Excavation.                     holes, Nov-22 to Feb-                                                        hole.
                                      23.
                                     Drill 46 rock borings   42-inch diameter        Mono-hammer DTH............  2 borings/day, 5 hours/         \1\ 24
                                      (50 cy), May-22 to      casing.                                              boring.
                                      Jun-22.
West closure wall--Berth 11          Drill 28 shafts, Aug-   42-inch diameter        Mono-hammer DTH............  1 shaft/day, 10 hours/day.          28
 Abutment--Install Piles.             22 to Mar-23.           casing.
Berth 11--Remove Shutter Panels....  112 panels, Oct-22 to   Demolish shutter        Hydraulic rock hammering...  5 hours/day...............        * 56
                                      Mar-23\+\.              panels.
Berth 11 Face--Mechanical Rock       3,500 cy, Oct-22 to     Excavate Bedrock......  Hydraulic rock hammering...  12 hours/day..............       * 100
 Removal at Basin Floor.              Mar-23\+\.
                                     Drill 2,201 relief      4-6 inch holes........  Mono-hammer DTH............  27 holes/day, 22.2 minutes/       * 82
                                      holes, Oct-22 to Mar-                                                        hole.
                                      23\+\.
Berth 11 Face--Mechanical Rock at    Drill 365 rock borings  42-inch diameter        Mono-hammer DTH............  2 borings/day, 5 hours/            183
 Abutment.                            (1,220 cy), Jul-22 to   casing.                                              boring.
                                      Jan-23.
Dry Dock 1 North Entrance--Drill     Drill 100 rock          9-inch holes..........  Mono-hammer DTH............  2 holes/day, 2 hours/hole.      \1\ 52
 Tremie Tie Downs.                    anchors, Jan-23 to
                                      Mar-23.
Dry Dock 1 North Entrance--Install   Install 96 sheet        28-inch wide Z-shaped   Impact with initial          8 sheets/day, 5 minutes             12
 Temporary Cofferdam.                 piles, Dec-22 to Mar-   sheets.                 vibratory set.               and 300 blows/pile.
                                      23.
Berth 1--Remove Sheet Piles........  Remove 12 sheet piles,  25-inch wide Z-shaped   Hydraulic rock hammering...  6 hours/day...............         * 3
                                      Mar-23 \+\.             sheets.
Berth 1 Top of Wall--Demolition For  30 lf\+\, Mar-23 \+\..  Mechanical concrete     Hydraulic rock hammering...  10 hours/day..............         * 6
 Waler Installation.                                          demolition.
                                    --------------------------------------------------------------------------------------------------------------------
    Totals.........................  539 shafts/borings,     ......................  ...........................  ..........................      1,537
                                      2,855 holes/
                                      anchors,422 sheet
                                      piles.
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\+\ These activities may continue into subsequent construction years pursuant to a proposed authorization.
* These activities will begin in year 1 of this IHA request and may continue into following construction years pursuant to a proposed authorization.
  Only the number of production days occurring in year 1 are presented.

Specific Geographic Region

    The shipyard is located in the Piscataqua River in Kittery, Maine. 
The Piscataqua River originates at the boundary of Dover, New 
Hampshire, and Eliot, Maine (see Figure 1 below). The river flows in a 
southeasterly direction for 2,093 meters (m) (13 miles (mi)) before 
entering Portsmouth Harbor and emptying into the Atlantic Ocean. The 
lower Piscataqua River is part of the Great Bay Estuary system and 
varies in width and depth. Many large and small islands break up the 
straight-line flow of the river as it continues toward the Atlantic 
Ocean. Seavey Island, the location of the proposed activities, is 
located in the lower Piscataqua River approximately 500 m from its 
southwest bank, 200 m from its north bank, and approximately 4,000 m 
(2.5 mi) from the mouth of the river.
    Water depths in the proposed project area range from 6.4 m (21 feet 
(ft) to 11.9 m (39 ft) at Berths 11, 12, and 13. Water depths in the 
lower Piscataqua River near the proposed project area range from 15 ft 
in the shallowest areas to 69 ft in the deepest areas. The river is 
approximately 914 m (3,300 ft) wide near the proposed project area, 
measured from the Kittery shoreline north of Wattlebury Island to the 
Portsmouth shoreline west of Peirce Island. The furthest direct line of 
sight from the proposed project area would be 1,287 m (0.8 mi) to the 
southeast and 418 m (0.26 mi) to the northwest.
    Much of the shoreline in the proposed project area is composed of 
hard shores (rocky intertidal). In general, rocky intertidal areas 
consist of bedrock that alternates between marine and terrestrial 
habitats, depending on the tide (Department of the Navy 2013). Rocky 
intertidal areas consist of ``bedrock, stones, or boulders that singly 
or in combination cover 75 percent or more of an area that is covered 
less than 30 percent by vegetation'' (Navy 2013).
    The lower Piscataqua River is home to Portsmouth Harbor and is used 
by commercial, recreational, and military vessels. Between 150 and 250 
commercial shipping vessels transit the lower Piscataqua River each 
year (Magnusson et al. June 2012). Commercial fishing vessels are also 
very common in the river year-round, as are recreational vessels, which 
are more common in the warmer summer months. The shipyard is a dynamic 
industrial facility situated on an island with a narrow separation of 
waterways between the installation and the communities of Kittery and 
Portsmouth (see Figure 2). The predominant noise sources from Shipyard 
industrial operations consist of dry dock cranes; passing vessels; and 
industrial equipment (e.g., forklifts, loaders, rigs, vacuums, fans, 
dust collectors, blower

[[Page 11863]]

belts, heating, air conditioning, and ventilation (HVAC) units, water 
pumps, and exhaust tubes and lids). Other components such as 
construction, vessel ground support equipment for maintenance purposes, 
vessel traffic across the Piscataqua River, and vehicle traffic on the 
shipyard's bridges and on local roads in Kittery and Portsmouth produce 
noise, but such noise generally represents a transitory contribution to 
the average noise level environment (Blue Ridge Research and Consulting 
(BRRC) 2015; ESS Group 2015). Ambient sound levels recorded at the 
shipyard are considered typical of a large outdoor industrial facility 
and vary widely in space and time (ESS Group 2015).
BILLING CODE 3510-22-P

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[GRAPHIC] [TIFF OMITTED] TN02MR22.048


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[GRAPHIC] [TIFF OMITTED] TN02MR22.049

BILLING CODE 3510-22-C

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Detailed Description of Specific Activity

    Preparatory work for P-381 in Year 1 as proposed for this IHA can 
be generally grouped into four categories: center wall support and tie-
in, structural reinforcement of super flood basin sidewalls and 
entrance, mechanical bedrock removal, and demolition of super flood 
basin wall components. Each category involves one or more activities 
expected to result in harassment of marine mammals.
    Center wall support and tie-in--The location of the future center 
wall requires reinforcement to allow placement of the large pre-cast 
monolith structures forming the separation between the two new dry 
docking positions. Specifically, the floor of the existing basin must 
be able to provide an adequate foundation for the pre-cast monoliths 
that will make up the dry dock interiors and center wall. The basin 
floor will be reinforced by 38, 84-inch (in) diameter shafts throughout 
the footprint of the center wall that will be filled with concrete to 
create the structural support piles for the center wall. The shafts 
will be installed using a cluster drill consisting of multiple down-
the-hole (DTH) hammers.
    Preparations for the center wall also require the installation of a 
relatively short length of sheet pile wall to create a connection 
between the existing west closure wall and the center wall. In 
construction year 1, 16, 28-in wide, Z-shaped sheet piles would be 
installed for the tie-in on the westerly end of the center wall 
footprint where it will connect to the west closure wall structure. The 
sheet piles will be installed using an initial vibratory set followed 
by driving with impact hammers. The remaining sheet piles will be 
proposed for installation in the following construction years and 
described in the subsequent rulemaking/LOA application.
    Structural reinforcement of super flood basin sidewalls and 
entrance--The existing super flood basin walls must be reinforced to 
allow adjacent bedrock removal and to provide support for the future 
dry dock walls. Bedrock removal is required to establish the deeper 
floor elevations needed for the project. The existing walls must be 
reinforced to prevent undermining during rock removal which could cause 
the walls to collapse.
    Wall reinforcement activities will include the installation of a 
sheet pile guide wall along the Berth 11 end wall. The guide wall will 
support the installation of an adjacent secant pile structural support 
wall that will be installed landside. In construction year 1, 24, 28-
in, Z-shaped sheet piles will be installed for the guide wall. The 
guide wall sheet piles will be placed using an initial vibratory set 
followed by driving with impact hammers. The remaining guide wall sheet 
piles will be proposed for installation in the following construction 
years and described in the subsequent rulemaking/LOA application.
    The conversion of the existing west closure wall to the Dry Dock 1 
North entrance requires reinforcement of the section of the west 
closure wall that will become the new dry dock entrance. The existing 
structure will be reinforced by drilling shafts through its interior 
into the underlying bedrock. The shafts will be filled with concrete to 
create structural piles. This activity will not occur in the water and 
will not create underwater noise impacts. The structure will then be 
surrounded by a temporary cofferdam. In construction Year 1, the 
cofferdam base will be constructed with 24, 28-in wide, Z-shaped sheet 
piles. The sheet piles will be installed using an initial vibratory set 
followed by driving with impact hammers. The remainder of cofferdam 
construction will be proposed in the following construction years and 
described in the subsequent rulemaking/LOA application.
    Additional preparatory work in the west closure wall area involves 
the installation of support tie downs for future tremie concrete work. 
The tie downs require the placement of an estimated 51 rock anchors 
requiring 9-in diameter holes. The rock anchors will be installed using 
a rotary drill.
    Along the northern section of the west closure wall, at its 
junction with Berth 11, reinforcement piles will be installed to 
strengthen the abutment area. The reinforcement piles will be 
constructed by drilling 28, 42-in diameter shafts that will be filled 
with concrete to create a pile wall. The shafts will be constructed 
using a DTH cluster drill.
    Mechanical bedrock removal--Bedrock will be mechanically excavated 
using various methods appropriate for the removal location and as 
needed to avoid damage to adjacent structures. Bedrock removal is 
required in several locations throughout the basin area. Three methods 
of rock removal will be employed that may result in injury or 
harassment of marine mammals:

[ssquf] Bedrock excavation with a hydraulic rock hammer (i.e., hoe ram 
or breaker)
[ssquf] Installation of relief holes (4- to 6-in diameter) using a DTH 
drill
[ssquf] Removal of rock using DTH drilling with 36-in cluster drill

    Two primary areas of mechanical rock removal are scheduled for Year 
1 of the project: The west closure wall footprint and the Berth 11 
face. Both sites require the use of the three methods presented in the 
bulleted list above.
    Preparation of the west closure wall area requires the removal of 
bedrock with a hydraulic hammer along with the DTH drilling 500, 4-6 in 
diameter relief holes and the drilling of 19 rock borings with a 36-in 
diameter DTH cluster drill. Approximately 905 cubic yards (cy) of 
bedrock are anticipated to be removed from the west closure wall area.
    Bedrock removal is also required along the Berth 11 face. Again, 
the rock will be removed with a hydraulic hammer: By drilling 351, 4-6-
in diameter relief holes plus drilling 8 rock borings with 36-in 
diameter DTH cluster drill. Approximately 415 cy of bedrock are 
anticipated to be removed during construction Year 1. The remaining 
bedrock will be proposed for removal in the following construction 
years and described in the rulemaking/subsequent LOA application.
    Demolition of super flood basin wall components--Demolition of 
existing wall structures includes the removal of shutter panels, 
granite quay walls, sheet piles, and concrete making up the super flood 
basin. Demolition of existing wall structures would largely be 
conducted using a rock hammer but some features would be removed by 
torch cutting. Torch cutting would not generate noise that would be 
harmful to marine mammals and therefore not discussed further.
    Portions of the basin west closure wall will be demolished by 
extracting the sheet piles with a vibratory hammer. 238, 18-in wide, 
flat sheet piles will be removed.
    Sections of the existing concrete shutter panels making up the face 
of Berth 11 will be removed with a hydraulic rock hammer. 
Approximately112 panels would be removed in construction Year 1. The 
remaining shutter panels will be proposed for removal in the following 
construction years and described in the rulemaking/subsequent LOA that 
application.
    Berth 1 demolition includes removal of the existing sheet pile wall 
and portions of the underlying granite block quay wall. In construction 
year 1, 12, 25-in wide, Z-shaped sheet piles and approximately 610 cy 
of granite would be removed. The sheet piles and the granite block quay 
wall will be removed with a hydraulic rock hammer with the remaining 
sheet piles and granite blocks proposed for removal in the following 
construction years and described in the subsequent rulemaking/LOA 
application.

[[Page 11867]]

    A section of Berth 1 requires the installation of a waler (steel 
beam) for structural support. To accommodate the waler, about 9.144 m 
(30 linear ft) of concrete wall will be removed using a hydraulic rock 
hammer in construction Year 1 with the remaining concrete wall proposed 
for removal in the following construction years and described in the 
subsequent rulemaking/LOA application.

Overall Noise Producing Activities

    Two types of piles will be installed or removed with pile driving 
equipment during construction Year 1: 28-in wide, Z-shaped sheet piles 
and 18-in wide, flat sheet piles. The installation of 28-in wide, Z-
shaped steel sheets would use a combination of vibratory and impact 
hammers, whereas the removal of 18-in wide, flat sheet piles would use 
only vibratory hammers.
    Pile installation/removal would occur using barge mounted cranes 
equipped with both vibratory and impact hammers. Piles would be 
installed initially using vibratory means and then finished with impact 
hammers, if necessary. Impact hammers would also be used to push 
obstructions out of the way and where sediment conditions do not permit 
the efficient use of vibratory hammers. To the extent practicable, it 
is assumed that the piles installed for this project would be set with 
a vibratory hammer and then finished with an impact hammer in order to 
reach bearing depth or to have the required load-bearing capacity if 
installed using vibratory methods only. Pile removal activities would 
use vibratory hammers exclusively.
    The removal of bedrock and the demolition of concrete shutter 
panels and granite blocks during construction Year 1 would be by 
mechanical means. These features would be demolished using a hydraulic 
rock hammer or hoe ram (a portion of bedrock removal would also use DTH 
mono hammers and cluster drilling).
    Two methods of rock excavation would be used during construction 
Year 1: rotary drill and DTH excavation. DTH excavation using mono-
hammers would be used for bedrock removal, to create shafts for support 
piles and tie downs, and for the excavation of relief holes during 
mechanical bedrock removal. For the largest shafts (greater than 42-in 
in diameter) DTH excavation would use a cluster drill. A cluster drill 
uses multiple mono-hammers within a single bit to efficiently break up 
bedrock and create large diameter holes. Rotary drilling is considered 
an intermittent, non-impulsive noise source, similar to vibratory pile-
driving.

Concurrent Activities

    In order to maintain project schedules, it is likely that multiple 
pieces of equipment would operate at the same time within the basin. 
Given the spatial constraints of the project area, a maximum of five 
pieces of equipment could potentially operate in the project area at a 
single time. Table 2 provides a summary of possible equipment 
combinations that could be used simultaneously over the course of the 
construction year. An analysis of concurrent activities with respect to 
noise generation from multiple sources is provided in the Estimated 
Take section.

            Table 2--Summary of Multiple Equipment Scenarios
------------------------------------------------------------------------
            Quantity                             Equipment
------------------------------------------------------------------------
2...............................  Rotary Drill (2).
2...............................  Cluster Drill (1), Rotary Drill (1).
2...............................  Cluster Drill (2).
3...............................  Cluster Drill (2), Vibratory Hammer
                                   (1).
5...............................  Cluster Drill (2), Vibratory Hammer
                                   (1), Mono-hammer DTH(1), Rotary Drill
                                   (1).
4...............................  Cluster Drill (1), Rock Hammering (1),
                                   Mono-hammer DTH (1), Rotary Drill
                                   (1).
2...............................  Mono-hammer DTH (1), Rock Hammer (1).
3...............................  Mono-hammer DTH (1), Rock Hammer (2).
------------------------------------------------------------------------
Source: 381 Constructors 2021.

    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. 
Additional information regarding population trends and threats may be 
found in NMFS' Stock Assessment Reports (SARs; https://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 with expected potential for occurrence in 
the Piscataqua River in Kittery, Maine, and summarizes information 
related to the population or stock, including regulatory status under 
the MMPA and ESA and potential biological removal (PBR), where known. 
For taxonomy, NMFS follows Committee on Taxonomy (2021). 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 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 for most species 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 Marine Mammal SARs. All values presented in Table 3 
are the most recent available at the time of publication and are 
available in the final 2020 SARs (Hayes et al., 2021) and draft 2021 
SARs, available online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/draft-marine-mammal-stock-assessment-reports.

                                    Table 3--Marine Mammals With Potential Presence Within the Proposed Project Area
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                         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 Cetartiodactyla--Cetacea--Superfamily Odontoceti (toothed whales)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Phocoenidae (porpoises):

[[Page 11868]]

 
    Harbor porpoise.................  Phocoena phocoena......  Gulf of Maine/Bay of     -;N                 95,543 (0.31; 74,034;         851        164
                                                                Fundy.                                       2016).
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                         Order Carnivora--Superfamily 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 \4\ (0.22;           1,389      4,453
                                                                                                             22,785; 2016).
    Harp seal.......................  Pagophilus               Western North Atlantic.  -;N                 7,600,000                 426,000    178,573
                                       groenlandicus.                                                        (unk,7,100.000, 2019).
    Hooded seal.....................  Cystophora cristata....  Western North Atlantic.  -;N                 593,500...............    Unknown      1,680
--------------------------------------------------------------------------------------------------------------------------------------------------------
\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-assessment-reports-region#reports. CV is coefficient of variation; Nmin is the minimum estimate of stock abundance.
\3\ These values, found in NMFS' 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\ This abundance value and the associated PBR value reflect the US population only. Estimated abundance for the entire Western North Atlantic stock,
  including animals in Canada, is 451,600. The annual M/SI estimate is for the entire stock.

    All species that could potentially occur in the proposed action 
area are included in Table 2. More detailed descriptions of marine 
mammals in the PNSY project area are provided below.

Harbor Porpoise

    Harbor porpoises occur from the coastline to deep waters (>1800 m); 
Westgate et al. 1998), although the majority of the population is found 
over the continental shelf (Hayes et al., 2020). In the project area, 
only the Gulf of Maine/Bay of Fundy stock of harbor porpoise may be 
present. This stock is found in U.S. and Canadian Atlantic waters and 
is concentrated in the northern Gulf of Maine and southern Bay of Fundy 
region, generally in waters less than 150 m deep (Waring et al., 2016).
    The Navy has been collecting data on marine mammals in the 
Piscataqua River since 2017 through construction monitoring and non-
construction related monthly surveys (2017-2018). Three harbor 
porpoises were observed travelling quickly through the river channel 
during marine mammal monitoring conducted between April and December 
2017 in support of the Berth 11 Waterfront Improvements Project 
(Cianbro 2018a). Two harbor porpoises were observed during construction 
monitoring that occurred between January 2018 and January 2019 (Cianbro 
2018b; Navy 2019). One harbor porpoise was observed in March 2017 
during non-construction related surveys conducted on 12 days (one per 
month) in 2017, and two harbor porpoises (one in August and one in 
November) were observed in monthly surveys conducted in 2018 (Naval 
Facilities Engineering Systems Command (NAVFAC) Mid-Atlantic 2018, 
2019b). There was one sighting of harbor porpoise during P-310 year 1 
monitoring events (May through December 2020) (NAVFAC 2021). To date, 
no harbor porpoise have been sighted in calendar year 2021 (Stantec 
2021).

Harbor Seal

    The harbor seal is found in all nearshore waters of the North 
Atlantic and North Pacific Oceans and adjoining seas above about 
30[ordm] N (Burns, 2009). In the western North Atlantic, harbor seals 
are distributed from the eastern Canadian Arctic and Greenland south to 
southern New England and New York, and occasionally to the Carolinas 
(Hayes et al., 2020). Haulout and pupping sites are located off 
Manomet, MA and the Isles of Shoals, ME (Waring et al., 2016).
    Harbor seals are the most abundant pinniped in the Piscataqua 
River. The majority of harbor seals occur along the Maine coast with a 
large portion of them hauling out at the Isles of Shoals (see Figure 4-
1 of the application). Pupping season for harbor seals is May to June. 
No harbor seal pups were observed during the surveys (Cianbro 2018a, b) 
as pupping sites are north of the Maine-New Hampshire border (Waring et 
al. 2016). During construction monitoring between the months of April 
and December 2017, 199 harbor seals were observed (Cianbro 2018a) in 
the project area. A total of 249 harbor seals were observed during 
construction monitoring between the months of January 2018 and January 
2019 (Navy 2019). The primary behaviors observed during monitoring were 
milling that occurred almost 60 percent of the time followed by 
swimming and traveling by the proposed project area at 29 percent and 
12 percent, respectively (Cianbro 2018a). A total of 17 and 83 harbor 
seals were observed during the one-day monthly surveys conducted in 
2017 and 2018, respectively (NAVFAC Mid-Atlantic 2018, 2019b). Between 
May and December of 2020 (NAVFAC 2021), 721 harbor seals were sighted 
during construction monitoring (NAVFAC 2021). A total of 302 harbor 
seals have been observed during construction monitoring of the project 
area between January 2021 and November 2021 (Stantec 2021).

Gray Seal

    There are three major populations of gray seals found in the world; 
eastern Canada (western North Atlantic stock), northwestern Europe and 
the Baltic Sea. Gray seals in the project area belong to the western 
North Atlantic stock. The range for this stock is from New Jersey to 
Labrador. Current population trends show that gray seal abundance is 
likely increasing in the U.S. Atlantic Exclusive Economic Zone (EEZ) 
(Hayes et al., 2020). Although the rate of increase is unknown, surveys 
conducted since their arrival in the 1980s indicate a steady increase 
in abundance in both Maine and Massachusetts (Hayes et al., 2018). It 
is believed that recolonization by Canadian gray seals is the source of 
the U.S. population (Hayes et al., 2018).
    There were 24 gray seals observed within the proposed project area 
between the months of April and December 2017 (Cianbro 2018a) and a 
total of 12 observed during the January 2018 to January 2019 
construction monitoring period (Navy 2019). Ten of

[[Page 11869]]

the 12 observation occurred during the winter months. (Navy 2019). The 
primary behavior observed during surveys was milling at just over 60 
percent of the time followed by swimming within and traveling through 
the proposed project area. Gray seals were observed foraging 
approximately 5 percent of the time (Cianbro 2018a). The one-day 
monthly marine mammal surveys during 2017 and 2018 recorded six and 
three sightings, respectively, of gray seal (NAVFAC Mid-Atlantic 2018, 
2019b). A total of 47 gray seals were observed during P-310 Year 1 
monitoring events from May through December 2020 (NAVFAC 2021). Pupping 
season for gray seals is December through February. No gray seal pups 
were observed during the surveys (Cianbro 2018a, b) as pupping sites 
for gray seals (like harbor seals) are north of Maine-New Hampshire 
border (Waring et al. 2016). In 2021, monitoring activities have 
sighted 9 gray seals thus far (Stantec 2021).

Hooded Seal

    Hooded seals are also members of the true seal family (Phocidae) 
and are generally found in deeper waters or on drifting pack ice. The 
world population of hooded seals has been divided into three stocks, 
which coincide with specific breeding areas, as follows: 1) Northwest 
Atlantic, 2) Greenland Sea, and 3) White Sea (Waring et al., 2020). The 
hooded seal is a highly migratory species, and its range can extend 
from the Canadian arctic to Puerto Rico. In U.S. waters, the species 
has an increasing presence in the coastal waters between Maine and 
Florida (Waring et al., 2019). In the U.S., they are considered members 
of the western North Atlantic stock and generally occur in New England 
waters from January through May and further south in the summer and 
fall seasons (Waring et al., 2019).
    Hooded seals are known to occur in the Piscataqua River; however, 
they are not as abundant as the more commonly observed harbor seal. 
Anecdotal sighting information indicates that two hooded seals were 
observed from the Shipyard in August 2009, but no other observations 
have been recorded (Trefry November 20, 2015). Hooded seals were not 
observed during marine mammal monitoring or survey events that took 
place in 2017, 2018, and 2020 (Cianbro 2018a, b; NAVFAC Mid-Atlantic 
2018, 2019b; Navy 2019; NAVFAC 2021). To date no hooded seals have been 
sighted in 2021 (Stantec 2021).

Harp Seal

    The harp seal is a highly migratory species, its range extending 
throughout the Arctic and North Atlantic Oceans. The world's harp seal 
population is separated into three stocks, based on associations with 
specific locations of pagophilic breeding activities: (1) Off eastern 
Canada, (2) on the West Ice off eastern Greenland, and (3) in the White 
Sea off the coast of Russia. The largest stock, which includes two 
herds that breed either off the coast of Newfoundland/Labrador or near 
the Magdelan Islands in the Gulf of St. Lawrence, is equivalent to the 
western North Atlantic stock. Harp seals that occur in the United 
States are considered members of the western North Atlantic stock and 
generally occur in New England waters from January through May (Waring 
et al., 2020).
    Harp seals are known to occur in the Piscataqua River; however, 
they are not as abundant as the more commonly observed harbor seal and 
were last documented in the river in May of 2020 (Stantec 2020). Two 
harp seals were sighted on two separate occasions (on May 12 and May 
14, 2020) during construction monitoring for P-310 (NAVFAC 2021). No 
pile driving was occurring at the time of the sighting. Previous to 
that, the last harp seal sighting was in 2016 (NAVFAC Mid-Atlantic 
2016; NMFS 2016b). Harp seals were not observed during marine mammal 
monitoring or survey events that took place in 2017 and 2018 (Cianbro 
2018a, b; NAVFAC Mid-Atlantic 2018, 2019b; Navy 2019). To date no harp 
seals have been sighted in 2021 (Stantec 2021).

Unusual Mortality Events (UMEs)

    Since July 2018, elevated numbers of harbor seal and gray seal 
mortalities have occurred across Maine, New Hampshire and 
Massachusetts. This event was declared a UME, but it is now considered 
non-active and pending closing. Information on this UME is available 
online at: https://www.fisheries.noaa.gov/new-england-mid-atlantic/marine-life-distress/2018-2020-pinniped-unusual-mortality-event-along.

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. Current data indicate that 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) recommended that marine mammals be divided 
into functional hearing groups based on directly measured or estimated 
hearing ranges on the basis of available behavioral response data, 
audiograms derived using auditory evoked potential techniques, 
anatomical modeling, and other data. 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]
------------------------------------------------------------------------
            Hearing group                 Generalized hearing range *
------------------------------------------------------------------------
Low-frequency (LF) cetaceans (baleen  7 Hz to 35 kHz.
 whales).
Mid-frequency (MF) cetaceans          150 Hz to 160 kHz.
 (dolphins, toothed whales, beaked
 whales, bottlenose whales).
High-frequency (HF) cetaceans (true   275 Hz to 160 kHz.
 porpoises, Kogia, river dolphins,
 cephalorhynchid, Lagenorhynchus
 cruciger & L. australis).
Phocid pinnipeds (PW) (underwater)    50 Hz to 86 kHz.
 (true seals).

[[Page 11870]]

 
Otariid pinnipeds (OW) (underwater)   60 Hz to 39 kHz.
 (sea lions 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. 
Five marine mammal species (one cetacean and four pinniped (all phocid) 
species) have the reasonable potential to co-occur with the proposed 
survey activities. Please refer to Table 3. The only cetacean species 
that may be present, the harbor porpoise, is classified as a high-
frequency cetacean.

Potential Effects of Specified Activities on Marine Mammals and Their 
Habitat

    This section includes a summary and 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 how those 
impacts on individuals are likely to impact marine mammal species or 
stocks.

Description of Sound

    Sound travels in waves, the basic components of which are 
frequency, wavelength, velocity, and amplitude. Frequency is the number 
of pressure waves that pass by a reference point per unit of time and 
is measured in hertz (Hz) or cycles per second. Wavelength is the 
distance between two peaks of a sound wave; lower frequency sounds have 
longer wavelengths than higher frequency sounds. Amplitude is the 
height of the sound pressure wave or the `loudness' of a sound and is 
typically measured using the dB scale. A dB is the ratio between a 
measured pressure (with sound) and a reference pressure (sound at a 
constant pressure, established by scientific standards). It is a 
logarithmic unit that accounts for large variations in amplitude; 
therefore, relatively small changes in dB ratings correspond to large 
changes in sound pressure. When referring to sound pressure levels 
(SPLs) (the sound force per unit area), sound is referenced in the 
context of underwater sound pressure to one microPascal ([mu]Pa). One 
pascal is the pressure resulting from a force of one newton exerted 
over an area of one square meter. The source level (SL) represents the 
sound level at a distance of 1 m from the source (referenced to 1 
[mu]Pa). The received level is the sound level at the listener's 
position. Note that all underwater sound levels in this document are 
referenced to a pressure of 1 [micro]Pa and all airborne sound levels 
in this document are referenced to a pressure of 20 [micro]Pa.
    Root mean square (RMS) is the quadratic mean sound pressure over 
the duration of an impulse. RMS is calculated by squaring all of the 
sound amplitudes, averaging the squares, and then taking the square 
root of the average (Urick 1983). RMS accounts for both positive and 
negative values; squaring the pressures makes all values positive so 
that they may be accounted for in the summation of pressure levels 
(Hastings and Popper 2005). This measurement is often used in the 
context of discussing behavioral effects, in part because behavioral 
effects, which often result from auditory cues, may be better expressed 
through averaged units than by peak pressures.
    When underwater objects vibrate or activity occurs, sound-pressure 
waves are created. These waves alternately compress and decompress the 
water as the sound wave travels. Underwater sound waves radiate in all 
directions away from the source (similar to ripples on the surface of a 
pond), except in cases where the source is directional. The 
compressions and decompressions associated with sound waves are 
detected as changes in pressure by aquatic life and man-made sound 
receptors such as hydrophones.
    Even in the absence of sound from the specified activity, the 
underwater environment is typically loud due to ambient sound. Ambient 
sound is defined as environmental background sound levels lacking a 
single source or point (Richardson et al., 1995), and the sound level 
of a region is defined by the total acoustical energy being generated 
by known and unknown sources. These sources may include physical (e.g., 
waves, earthquakes, ice, atmospheric sound), biological (e.g., sounds 
produced by marine mammals, fish, and invertebrates), and anthropogenic 
sound (e.g., vessels, dredging, aircraft, construction). A number of 
sources contribute to ambient sound, including the following 
(Richardson et al., 1995):
     Wind and waves: The complex interactions between wind and 
water surface, including processes such as breaking waves and wave-
induced bubble oscillations and cavitation, are a main source of 
naturally occurring ambient noise for frequencies between 200 Hz and 50 
kilohertz (kHz) (Mitson 1995). In general, ambient sound levels tend to 
increase with increasing wind speed and wave height. Surf noise becomes 
important near shore, with measurements collected at a distance of 8.5 
km from shore showing an increase of 10 dB in the 100 to 700 Hz band 
during heavy surf conditions;
     Precipitation: Sound from rain and hail impacting the 
water surface can become an important component of total noise at 
frequencies above 500 Hz, and possibly down to 100 Hz during quiet 
times;
     Biological: Marine mammals can contribute significantly to 
ambient noise levels, as can some fish and shrimp. The frequency band 
for biological contributions is from approximately 12 Hz to over 100 
kHz; and
     Anthropogenic: Sources of ambient noise related to human 
activity include transportation (surface vessels and aircraft), 
dredging and construction, oil and gas drilling and production, seismic 
surveys, sonar, explosions, and ocean acoustic studies. Shipping noise 
typically dominates the total ambient

[[Page 11871]]

noise for frequencies between 20 and 300 Hz. In general, the 
frequencies of anthropogenic sounds are below 1 kHz and, if higher 
frequency sound levels are created, they attenuate rapidly (Richardson 
et al., 1995). Sound from identifiable anthropogenic sources other than 
the activity of interest (e.g., a passing vessel) is sometimes termed 
background sound, as opposed to ambient sound.
    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 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 activity may be a negligible addition to the local 
environment or could form a distinctive signal that may affect marine 
mammals.
Description of Sounds Sources
    In-water construction activities associated with the project would 
include impact and vibratory pile installation and removal, rotary 
drilling, DTH, and rock hammering. The sounds produced by these 
activities fall into one of two general sound types: Impulsive and non-
impulsive (defined below). The distinction between these two sound 
types is important because they have differing potential to cause 
physical effects, particularly with regard to hearing (e.g., Ward 1997 
in Southall et al., 2007). Please see Southall et al. (2007) for an in-
depth discussion of these concepts.
    Impulsive sound sources (e.g., explosions, gunshots, sonic booms, 
impact pile driving) produce signals that are brief (typically 
considered to be less than one second), broadband, atonal transients 
(American National Standards Institute standards (ANSI) 1986; Harris 
1998; National Institute for Occupational Safety and Health (NIOSH) 
1998; International Organization for Standardization (ISO) 2003; ANSI 
2005) and occur either as isolated events or repeated in some 
succession. Impulsive sounds are all characterized by a relatively 
rapid rise from ambient pressure to a maximal pressure value followed 
by a rapid decay period that may include a period of diminishing, 
oscillating maximal and minimal pressures, and generally have an 
increased capacity to induce physical injury as compared with sounds 
that lack these features.
    Non-impulsive sounds can be tonal, narrowband, or broadband, brief 
or prolonged, and may be either continuous or non-continuous (ANSI 
1995; NIOSH 1998). Some of these non-impulsive sounds can be transient 
signals of short duration but without the essential properties of 
impulses (e.g., rapid rise time). Examples of non-impulsive sounds 
include those produced by vessels, aircraft, machinery operations such 
as drilling or dredging, vibratory pile driving, and active sonar 
systems. The duration of such sounds, as received at a distance, can be 
greatly extended in a highly reverberant environment.

Acoustic Impacts

    The introduction of anthropogenic noise into the aquatic 
environment from pile driving or drilling is the primary means by which 
marine mammals may be harassed from the Navy's specified activity. 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). In general, exposure to 
pile driving or drilling 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 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 or drilling 
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. mom 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., 2004; 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 decibels (dB). A TS can be 
permanent or 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 an 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; Ahroon et al., 1996; Henderson et 
al., 2008). PTS levels for marine mammals are estimates, as with the 
exception of a single study unintentionally inducing PTS in a harbor 
seal (Kastak et al., 2008), there are no empirical data measuring PTS 
in marine mammals 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

[[Page 11872]]

(Schlundt et al., 2000; Finneran et al., 2000, 2002). As described in 
Finneran (2015), 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 a 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.
    Currently, TTS data only exist for four species of cetaceans 
(bottlenose dolphin (Tursiops truncatus), beluga whale (Delphinapterus 
leucas), harbor porpoise, and Yangtze finless porpoise (Neophocoena 
asiaeorientalis) and five species of pinnipeds exposed to a limited 
number of sound sources (i.e., mostly tones and octave-band noise) in 
laboratory settings (e.g., Finneran 2015). TTS was not observed in 
trained spotted (Phoca largha) and ringed (Pusa hispida) seals exposed 
to impulsive noise at levels matching previous predictions of TTS onset 
(Reichmuth et al., 2016). In general, harbor seals (Kastak et al., 
2005; Kastelein et al., 2012a) and harbor porpoises (Lucke et al., 
2009; Kastelein et al., 2012b) have a lower TTS onset than other 
measured pinniped or cetacean species (Finneran 2015). Additionally, 
the existing marine mammal TTS data come from a limited number of 
individuals within these species. There are no data available on noise-
induced hearing loss for mysticetes. For summaries of data on TTS in 
marine mammals or for further discussion of TTS onset thresholds, 
please see Southall et al. (2007), Finneran and Jenkins (2012) and 
Finneran (2015).
    Behavioral Harassment--Exposure to noise from pile driving and 
removal also has the potential to behaviorally disturb marine mammals. 
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. 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 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).
    Disturbance may result in changing durations of surfacing and 
dives, number of blows per surfacing, or moving direction and/or speed; 
reduced/increased vocal activities; changing/cessation of certain 
behavioral activities (such as socializing or feeding); visible startle 
response or aggressive behavior (such as tail/fluke slapping or jaw 
clapping); avoidance of areas where sound sources are located. 
Pinnipeds may increase their haul out time, possibly to avoid in-water 
disturbance (Thorson and Reyff 2006). 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). 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. Please see Appendices B-C of Southall et 
al., (2007) for a review of studies involving marine mammal behavioral 
responses to sound.
    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). 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.
    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

[[Page 11873]]

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 this project based on observations of 
marine mammals during previous, similar projects in the area.
    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.
    Airborne Acoustic Effects--Although pinnipeds are known to haul-out 
regularly on man-made objects, we believe that incidents of take 
resulting solely from airborne sound are unlikely due to the sheltered 
proximity between the proposed project area and the haulout sites (on 
the opposite side of the island where activities are occuring). There 
is a possibility that an animal could surface in-water, but with head 
out, within the area in which airborne sound exceeds relevant 
thresholds and thereby be exposed to levels of airborne sound that we 
associate with harassment, but any such occurrence would likely be 
accounted for in our estimation of incidental take from underwater 
sound. Therefore, authorization of incidental take resulting from 
airborne sound for pinnipeds is not warranted, and airborne sound is 
not discussed further here. Cetaceans are not expected to be exposed to 
airborne sounds that would result in harassment as defined under the 
MMPA.

Potential Effects on Marine Mammal Habitat

    Water quality--Temporary and localized reduction in water quality 
will occur as a result of in-water construction activities. Most of 
this effect will occur during the installation of piles and bedrock 
removal when bottom sediments are disturbed. The installation of piles 
and bedrock removal an will disturb bottom sediments and may cause a 
temporary increase in suspended sediment in the project area. Using 
available information collected from a project in the Hudson River, 
pile driving activities are anticipated to produce total suspended 
sediment (TSS) concentrations of approximately 5.0 to 10.0 mg/L above 
background levels within approximately 300 feet (91 meters) of the pile 
being driven (Federal Highway Administration (FHWA) 2012). During pile 
extraction, sediment attached to the pile moves vertically through the 
water column until gravitational forces cause it to slough off under 
its own weight. The small resulting sediment plume is expected to 
settle out of the water column within a few hours. Studies of the 
effects of turbid water on fish (marine mammal prey) suggest that 
concentrations of suspended sediment can reach thousands of milligrams 
per liter before an acute toxic reaction is expected (Burton 1993). The 
TSS levels expected for pile driving or removal (5.0 to 10.0 mg/L) are 
below those shown to have adverse effects on fish (580.0 mg/L for the 
most sensitive species, with 1,000.0 mg/L more typical) and benthic 
communities (390.0 mg/L (Environmental Protection Agency 1986)).
    Impacts to water quality from DTH mono-hammers are expected to be 
similar to those described for pile driving. Impacts to water quality 
would be localized and temporary and would have negligible impacts on 
marine mammal habitat. The cluster drill system and rotary drilling of 
shafts would have negligible impacts on water quality from sediment 
resuspension because the system would operate within a casing set into 
the bedrock. The cluster drill would collect excavated material inside 
of the apparatus where it would be lifted to the surface and placed 
onto a barge for subsequent disposal.
    Turbidity within the water column has the potential to reduce the 
level of oxygen in the water and irritate the gills of prey fish 
species in the proposed project area. However, turbidity plumes 
associated with the project would be temporary and localized, and fish 
in the proposed project area would be able to move away from and avoid 
the areas where plumes may occur. Therefore, it is expected that the 
impacts on prey fish species from turbidity, and therefore on marine 
mammals, would be minimal and temporary.
    Overall effects of turbidity and sedimentation are expected to be 
short-term, minor, and localized. Currents are strong in the area and, 
therefore, suspended sediments in the water column should dissipate and 
quickly return to background levels. Following the completion of 
sediment-disturbing activities, the turbidity levels are expected to 
return to normal ambient levels following the end of construction. In 
general, the area likely impacted by the project is relatively small 
compared to the available habitat in Great Bay Estuary.
    Effects on Potential Prey--Sound may affect marine mammals through 
impacts

[[Page 11874]]

on the abundance, behavior, or distribution of prey species (e.g., 
crustaceans, cephalopods, fish, zooplankton). Marine mammal prey varies 
by species, season, and location and, for some, is not well documented. 
Studies regarding the effects of noise on known marine mammal prey are 
described here.
    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 et al., 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, although 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; Cott 
et al., 2012). More commonly, though, the impacts of noise on fish are 
temporary.
    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 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 greatest potential impact to fish during construction would 
occur during impact pile driving, rock hammering, and DTH excavation 
(DTH mono-hammer and cluster drill). However, the duration of impact 
pile driving would be limited to the final stage of installation 
(``proofing'') after the pile has been driven as close as practicable 
to the design depth with a vibratory driver. Vibratory pile driving and 
rock hammering would possibly elicit behavioral reactions from fish 
such as temporary avoidance of the area but is unlikely to cause 
injuries to fish or have persistent effects on local fish populations. 
In addition, it should be noted that the area in question is low-
quality habitat since it is already highly developed and experiences a 
high level of anthropogenic noise from normal shipyard operations and 
other vessel traffic. In general, impacts on marine mammal prey species 
are expected to be minor and temporary.

In-Water Construction Effects on Potential Foraging Habitat

    The proposed activities would not result in permanent impacts to 
habitats used directly by marine mammals. The total seafloor area 
affected by pile installation and removal is a very small area compared 
to the vast foraging area available to marine mammals outside this 
project area. Construction may have temporary impacts on benthic 
invertebrate species, another marine mammal prey source. Direct benthic 
habitat loss would result with the permanent loss of approximately 3.5 
acres (14,164 square m) of benthic habitat from construction of the 
super flood basin. The water surface of Great Bay Estuary extends 
approximately 4.45 square miles (124,000,000 sf) at low tide (Mills No 
date). Therefore, the loss of 152,000 sf would represent approximately 
one-tenth of one percent of the benthic habitat in the estuary at low 
tide. However, the areas to be permanently removed are beneath and 
adjacent to the existing berths along the Shipyard's industrial 
waterfront and are regularly disturbed as part of the construction 
dredging to maintain safe navigational depths at the berths. Further, 
vessel activity at the berths creates minor disturbances of benthic 
habitats (e.g., vessel propeller wakes) during waterfront operations. 
Therefore, impacts of the project are not likely to have adverse 
effects on marine mammal foraging habitat in the proposed project area. 
The impacts will be temporary and highly localized, and no habitat will 
be permanently impacted by construction. Therefore, it is expected that 
impacts on foraging opportunities for marine mammals due to the project 
would be minimal.
    The area impacted by the project is relatively small compared to 
the available habitat just outside the project area, and there are no 
areas of particular importance that would be impacted by this project. 
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. As described in the preceding, the 
potential for the Navy's construction to affect the availability of 
prey to marine mammals or to meaningfully impact the quality of 
physical or acoustic habitat is considered to be insignificant.

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 
determination.
    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, in the 
form of behavioral disturbance, masking, and potential TTS, with a 
smaller amount of Level A harassment in the form of PTS. As described 
previously, no mortality is anticipated or proposed to be authorized

[[Page 11875]]

for this activity. Below we describe how the take is estimated.
    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 
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 take estimate.

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).
    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 (e.g., frequency, predictability, duty cycle), the environment 
(e.g., bathymetry), and the receiving animals (hearing, motivation, 
experience, demography, behavioral context) and can be difficult to 
predict (Southall et al., 2007, Ellison et al., 2012). Based on what 
the available science indicates and the practical need to use a 
threshold based on a factor that is both predictable and measurable for 
most activities, NMFS uses a generalized acoustic threshold based on 
received level to estimate the onset of behavioral harassment. NMFS 
predicts that marine mammals are likely to be behaviorally harassed in 
a manner we consider Level B harassment when exposed to underwater 
anthropogenic noise above received levels of 120 dB re 1 [mu]Pa (RMS) 
for continuous (e.g., vibratory pile-driving, drilling) and above 160 
dB re 1 [mu]Pa (RMS) for impulsive and/or intermittent (e.g., impact 
pile driving, DTH) sources. The Navy's construction includes the use of 
continuous and impulsive sources, and therefore the level of 120 and 
160 dB re 1 [mu]Pa (RMS) is applicable.
    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. The 
technical guidance identifies the received levels, or thresholds, above 
which individual marine mammals are predicted to experience changes in 
their hearing sensitivity for all underwater anthropogenic sound 
sources, and reflects the best available science on the potential for 
noise to affect auditory sensitivity. The technical guidance does this 
by identifying threshholds in the follow manner:
     Dividing sound sources into two groups (i.e., impulsive 
and non-impulsive) based on their potential to affect hearing 
sensitivity;
     Choosing metrics that best address the impacts of noise on 
hearing sensitivity, i.e., sound pressure level (peak SPL) and sound 
exposure level (SEL) (also accounting for duration of exposure); and
     Dividing marine mammals into hearing groups and developing 
auditory weighting functions based on the science supporting the fact 
that not all marine mammals hear and use sound in the same manner.
    These thresholds were developed by compiling and synthesizing the 
best available science and are provided in Table 5 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 https://www.fisheries.noaa.gov/national/marine-mammal-protection.
    As mentioned previously, the Navy's modification and expansion of 
Dry Dock 1 includes the use of impulsive (i.e., impact pile driving, 
DTH) and non-impulsive (i.e., drilling, vibratory pile driving) 
sources.

    Table 5--Thresholds Identifying the Onset of Permanent Threshold Shift for High Frequency Ceteaceans and
                                                    Pinnipeds
----------------------------------------------------------------------------------------------------------------
                                                     PTS onset acoustic thresholds * (received level)
             Hearing group              ------------------------------------------------------------------------
                                                  Impulsive                         Non-impulsive
----------------------------------------------------------------------------------------------------------------
High-Frequency (HF) Cetaceans..........  Cell 5: Lpk,flat: 202 dB;   Cell 6: LE,HF,24h: 173 dB.
                                          LE,HF,24h: 155 dB.
Phocid Pinnipeds (PW) (Underwater).....  Cell 7: Lpk,flat: 218 dB;   Cell 8: LE,PW,24h: 201 dB.
                                          LE,PW,24h: 185 dB.
----------------------------------------------------------------------------------------------------------------
* Dual metric acoustic 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 should also be considered.
Note: Peak sound pressure (Lpk) has a reference value of 1 [mu]Pa, and cumulative sound exposure level (LE) has
  a reference value of 1[mu]Pa\2\s. In this Table, thresholds are abbreviated to reflect American National
  Standards Institute standards (ANSI 2013). However, peak sound pressure is defined by ANSI as incorporating
  frequency weighting, which is not the intent for this Technical Guidance. Hence, the subscript ``flat'' is
  being included to indicate peak sound pressure should be flat weighted or unweighted within the generalized
  hearing range. The subscript associated with cumulative sound exposure level thresholds indicates the
  designated marine mammal auditory weighting function (HF cetaceans and PW pinnipeds) and that the recommended
  accumulation period is 24 hours. The 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 acoustic thresholds will be exceeded.

Ensonified Area

    Here, we describe operational and environmental parameters of the 
activity that will feed into identifying the area ensonified above the 
acoustic thresholds, which include source levels transmission loss 
coefficient.
    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:


[[Page 11876]]


TL = B * log10(R1/R2),

where

B = transmission loss coefficient (assumed to be 15)
R1 = the distance of the modeled SPL from the driven 
pile, and
R2 = the distance from the driven pile of the initial 
measurement.

    This formula neglects loss due to scattering and absorption, which 
is assumed to be zero here. The degree to which underwater sound 
propagates away from a sound source is dependent on a variety of 
factors, most notably the water bathymetry and presence or absence of 
reflective or absorptive conditions, including in-water structures and 
sediments. Spherical spreading occurs in a perfectly unobstructed 
(free-field) environment not limited by depth or water surface, 
resulting in a 6 dB reduction in sound level for each doubling of 
distance from the source (20*log(range)). Cylindrical spreading occurs 
in an environment in which sound propagation is bounded by the water 
surface and sea bottom, resulting in a reduction of 3 dB in sound level 
for each doubling of distance from the source (10*log(range)). 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 is a compromise that is often used under conditions 
where water depth increases as the receiver moves away from the 
shoreline, resulting in an expected propagation environment that would 
lie between spherical and cylindrical spreading loss conditions. 
Practical spreading was used to determine sound propagation for this 
project.
    The intensity of pile driving sounds is greatly influenced by 
factors such as the type of piles, hammers, and the physical 
environment in which the activity takes place. There are sound source 
level (SSL) measurements available for certain pile types and sizes 
from the similar environments from other Navy pile driving projects 
that were evaluated and used as proxy sound source levels to determine 
reasonable sound source levels likely to result from the pile driving 
and removal activities (Table 6). Some of the proxy source levels are 
expected to be more conservative, as the values are from larger pile 
sizes. Acoustic monitoring results and associated monitoring reports 
from past projects conducted at the shipyard and elsewhere were 
reviewed. Projects reviewed were those most similar to the specified 
activity in terms of drilling and rock hammering activities, type and 
size of piles installed, method of pile installation, and substrate 
conditions.

                                      Table 6--Summary of In-Water Pile Driving Source Levels (at 10 m From Source)
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                               Peak  (dB re 1
            Pile type             Installation method       Pile diameter          [mu]Pa)         RMS (dB re 1 [mu]Pa)      SEL (dB re 1 [mu]Pa\2\ sec)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Casing/Socket...................  Rotary Drill.......  102-inch \1\..........              NA  154 m.......................  NA
Shaft...........................  DTH Cluster Drill..  78-inch \2\...........              NA  195.2 (Level A).............  181
                                                                                               167 dB (Level B)............
Casing..........................  DTH mono-hammer....  42-inch \1\...........             194  167.........................  164
Rock anchor.....................  DTH mono-hammer....  9-inch \1\............             172  167.........................  146
Relief hole.....................  DTH mono-hammer....  4 to 6-inch \1\.......             170  167.........................  144
Z-shaped Sheet..................  Impact.............  28-inch \3\...........             211  196.........................  181
                                  Vibratory..........  28-inch \4\...........              NA  167.........................  167
Flat sheet......................  Vibratory..........  18-inch \5\...........              NA  163.........................  163
Bedrock and concrete demolition.  Rock Hammer \6 7\..  NA....................             197  184.........................  175
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Egger 2021a.
\2\ Egger 2021b.
\3\ A proxy value for impact pile driving 28-inch steel sheet piles could not be found so the proxy for a 30-inch steel pipe pile has been used (NAVFAC
  SW 2020 [p. A-4]).
\4\ A proxy value for vibratory pile driving 28-inch steel sheet piles could not be found so a proxy for a 30-inch steel pipe pile has been used (Navy
  2015 [p. 14]).
\5\ NMFS 2019 (p. 24484, Table 5).
\6\ Reyff 2018a.
\7\ Reyff 2018b.
Notes: All SPLs are unattenuated; dB = decibels; NA = Not applicable; single strike SEL are the proxy sources levels presented for impact pile driving
  and were used to calculate distances to PTS.
 dB re 1 [mu]Pa = dB referenced to a pressure of 1 microPascal, measures underwater SPL. dB re 1 [mu]Pa\2\-sec = dB referenced to a pressure of 1
  microPascal squared per second, measures underwater SEL.
 All recordings were made at 10 meters unless noted otherwise.

    With regards to the proxy values summarized in Table 6, very little 
information is available regarding source levels for in-water rotary 
drilling activities. As a conservative measure and to be consistent 
with previously issued IHAs for similar projects in the region (Egger 
2021a; Dazey 2012), a proxy of 154 dB RMS is proposed for all rotary 
drilling activities.
    Rock hammering is analyzed as an impulsive noise source. For 
purposes of this analysis, it is assumed that the hammer would have a 
maximum strike rate of 460 strikes per minute and would operate for a 
maximum duration of 15 minutes before needing to reposition or stop to 
check progress. Therefore, noise impacts for rock hammering activities 
are assessed using the number of blows per 15-minute interval (6,900 
blows) and the number of 15-minute intervals anticipated over the 
course of the day based on the durations provided in Table 2-1 and 
Table 6-5. As with rotary drilling, very little information is 
available regarding source levels associated with nearshore rock 
hammering. Measurements taken for this activity as part of the Tappan 
Zee Bridge replacement project recorded sound levels as follows:

 197 dBpk, 184 dB RMS, 175 dB SEL (Reyff 2108a, 2018b)

    Since no other comparable proxy values were identified in the 
literature, the Navy is proposing to use the same proxy values for rock 
hammering activities associated with P-381.
    The Navy consulted with NMFS to obtain the appropriate proxy values 
for DTH mono-hammers. With regards to DTH mono-hammers, NMFS provided 
proxy values of 170 dBpk, 167 RMS, and 144 dB single strike SEL for 
holes 8-inches in diameter or less (Reyff 2020); 172 dBpk, 167 RMS, and 
146 dB single strike SEL for holes 8- to 18

[[Page 11877]]

inches in diameter (Guan and Miner 2020); and 194 dBpk, 167 RMS, and 
164 dB single strike SEL for holes 24- to 42-inches in diameter (Reyff 
2020, Denes et al 2019 as cited in NMFS 2021a). For the 78-inch DTH 
cluster drill, NMFS provided an RMS value of 195.2 based off of 
regression and extrapolation calculations of existing data. Because of 
the high number of hammers and strikes for this system, cluster drills 
were treated as a continuous sound source for the time component of 
Level A harassment but still used the impulsive thresholds. The Level B 
harassment sound source level at 10 m remained at 167 dB RMS (Heyvaert 
and Reyff, 2021 as cited in NMFS 2021b).
    In conjunction with the NMFS Technical Guidance (2018), in 
recognition of the fact that ensonified area/volume could be more 
technically challenging to predict because of the duration component in 
the new thresholds, NMFS developed a User Spreadsheet that includes 
tools to help predict a simple isopleth that can be used in conjunction 
with marine mammal density or occurrence to help predict takes. We note 
that, because of some of the assumptions included in the methods used 
for these tools, we anticipate that isopleths produced are typically 
going to be overestimates of some degree, which may result in some 
degree of overestimation of Level A harassment take. However, these 
tools offer the best way to predict appropriate isopleths when more 
sophisticated 3D modeling methods are not available, and NMFS continues 
to develop ways to quantitatively refine these tools and will 
qualitatively address the output where appropriate. For stationary 
sources (such as from impact and vibratory pile driving), the NMFS User 
Spreadsheet (2020) predicts the closest distance at which, if a marine 
mammal remained at that distance the whole duration of the activity, it 
would not incur PTS. Inputs used in the User Spreadsheet can be found 
in Appendix A of the Navy's application and the resulting isopleths are 
reported below (Tables 7 and 8).
    Calculated distances to Level A harassment (PTS Onset) and Level B 
harassment thresholds are large, especially for DTH and rock hammering 
activities. However, the full distance of sound propagation would not 
be reached due to the presence of land masses and anthropogenic 
structures that would prevent the noise from reaching nearly the full 
extent of the larger harassment isopleths. Refer to Figure 2 for the 
region of influence, which illustrates that the land masses preclude 
the sound from traveling more than approximately 870 m (3,000 ft) from 
the source, at most.
    Maximum distances are provided for the behavioral thresholds for 
in-water construction activities. Areas encompassed within the 
threshold (harassment zones) were calculated by using a Geographical 
Information System to clip the maximum calculated distances to the 
extent of the region of influence (ROI) (refer to Figure 2 for the 
ROI).
    Table 7 summarizes the calculated maximum distances corresponding 
to the underwater marine mammal harassment zones from impulsive (impact 
pile driving, rock hammering, DTH) and Table 8 for non-impulsive noise 
(vibratory pile driving, rotary drilling, etc.) and the area of the 
harassment zone within the ROI. The distances do not take the land 
masses into consideration, but the ensonified areas do. Neither 
consider the reduction that will be achieved by the required use of a 
bubble curtain and therefore all take estimates are considered 
conservative. Refer to Figures 6-9 through 6-11 of the application for 
the calculated maximum distances corresponding to the underwater marine 
mammal harassment zones from impulsive (impact pile driving, rock 
hammering, DTH) and non-impulsive noise (vibratory pile driving, rotary 
drilling) and the corresponding area of the harassment zone within the 
ROI.

                              Table 7--Calculated Distance and Areas of Level A and Level B Harassment for Impulsive Noise
                                                  [DTH, impact pile driving, hydraulic rock hammering]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                               Level A harassment (PTS onset) *       Level B harassment
                                                                                 Total    ------------------------------------------          *
             Activity                     Purpose          Count and size/     production     High frequency                        --------------------
                                                               duration           days      cetaceans (harbor     Phocid pinnipeds   Harbor porpoise and
                                                                                                porpoise)                                  phocids
--------------------------------------------------------------------------------------------------------------------------------------------------------
DTH Cluster Drill................  Foundation Support    38, 78-inch shafts.          247  84,380.4 m/0.417     37,909.7 m/0.417     13,594 m/0.417
                                    Piles for Center                                        km\2\.               km\2\.               km\2\.
                                    Wall.
DTH Cluster Drill................  Foundation Leveling   18, 78-inch shafts.          117  84,380.4 m/0.417     37,909.7 m/0.417     13,594 m/0.417
                                    Piles for Center                                        km\2\.               km\2\.               km\2\.
                                    Wall.
DTH Cluster Drill................  Center Wall--Access   38, 78-inch shafts.          133  84,380.4 m/0.417     37,909.7 m/0.417     13,594 m/0.417
                                    Support Platform.                                       km\2\.               km\2\.               km\2\.
DTH Mono-hammer..................  Center Wall--         6, 42-inch shafts..            6  3,880.3 m/0.417      1,743.3 m/0417km\2\  13,594 m/0.417
                                    Temporary Launching                                     km\2\.                                    km\2\.
                                    Piles.
DTH Mono-hammer..................  Center Wall Tie-      36, 9-inch holes...           18  244.8 m/0.074 km\2\  110 m/0.0229 km\2\.  13,594 m/0.417
                                    Downs.                                                                                            km\2\.
DTH Mono-hammer..................  Center Wall--Access   18, 9-inch holes...            9  244.8 m/0.0741       110 m/0.0229 km\2\.  13,594 m/0.417
                                    Platform Tie-Downs.                                     km\2\.                                    km\2\.
Impact Pile Driving..............  West Closure Wall     16, ** 28-inch Z-           ** 4  988.2 m/0.4034       444.0 m/0.2012       2,512 m/0.417
                                    Tie-In to Existing    shaped sheets.                    km\2\.               km\2\.               km\2\.
                                    Wall.
Impact Pile Driving..............  Berth 11 End Wall     60, 28-inch Z-                 7  1,568.6 m/0.417      704.7 m/0.365 km\2\  2,512 m/0.417
                                    Secant Pile Guide     shaped sheets.                    km\2\.                                    km\2\.
                                    Wall.
DTH Mono-hammer..................  Relief Holes Under    500, 4-6 inch holes           20  180.1 m/0.0481       80.9 m/0.015 km\2\.  13,594 m/0. 417
                                    West Closure Cell.                                      km\2\.                                    km\2\.
DTH Mono-hammer..................  Mechanical Rock       46, 42-inch casing            24  3,880.3 m/0.417      1,743.3 m/0.417      13,594 m/0.417
                                    Removal Along Face    advancements.                     km\2\.               km\2\.               km\2\.
                                    of Existing
                                    Abutment.
DTH Mono-hammer..................  Install Piles for     28, 42-inch shafts.           28  3,880.3 m/0.417      1,743.3 m/0.417      13,594 m/0.417
                                    Dry Dock 1 North                                        km\2\.               km\2\.               km\2\.
                                    Entrance Abutment.
DTH Mono-hammer..................  Relief Holes Under    2,201, ** 4-6 inch         ** 82  180.1 m/0.0481km\2\  80.9 m/0.015 km\2\.  13,594 m/0.417
                                    West Closure Cell.    holes.                                                                      km\2\.
DTH Mono-hammer..................  Mechanical Rock       365, 42-inch casing          183  3,880.3 m/0.417      1,743.3 m/0.417      13,594 m/0.417
                                    Removal Along Face    advancements.                     km\2\.               km\2\.               km\2\.
                                    of Existing
                                    Abutment.
DTH Mono-hammer..................  Dry Dock 1 Entrance   100, 9-inch holes..           52  132.9 m/0.0303       59.7 m/0.009km\2\..  13,594 m/0.417
                                    Tremie Tie Downs.                                       km\2\.                                    km\2\.

[[Page 11878]]

 
Impact Pile Driving..............  Install Sheet Piles   96, 28-inch Z-                12  1,568.6 m/0.417      704.7 m/0.365km\2\.  2,512 m/0.417
                                    for Dry Dock 1        shaped sheets.                    km\2\.                                    km\2\.
                                    North Entrance and
                                    Temporary Cofferdam.
Hydraulic Rock Hammer............  Removal of Sheetpile  2.5 hours..........        ** 10  5,860.0 m/0.417      2,633 m/0.4174km\2\  398 m/0.165 km\2\.
                                    and Granite Quay                                        km\2\.
                                    Wall (610 cy).
Hydraulic Rock Hammer............  Mechanical Rock       9 hours............           77  13,766 m/0.417       6,184.7 m/0.417      398 m/0.165 km\2\.
                                    Removal (985 cy)                                        km\2\.               km\2\.
                                    Under West Closure
                                    Cell.
Hydraulic Rock Hammer............  Shutter Panel         5 hours............        ** 56  9,303.1 m/0.417      4,179.6 m/0.417      398 m/0.165 km\2\.
                                    Demolition.                                             km\2\.               km\2\.
Hydraulic Rock Hammer............  Mechanical Rock       12 hours...........       ** 100  16,676.3 m/0.417     7,492.2 m/0.417      398 m/0.165 km\2\.
                                    Removal (3,500 cy)                                      km\2\.               km\2\.
                                    Along Face of
                                    Existing Berth 11
                                    at Basin Floor.
Hydraulic Rock Hammer............  P-310 Sheet Pile      12, 25-inch Z-              ** 3  10,505.4 m/0.417     4,719.8 m/0.417      398 m/0.1652 km\2\.
                                    Removal--Berth 1.     shaped sheets, 6                  km\2\.               km\2\.
                                                          hours.
Hydraulic Rock Hammer............  Berth 1 Top of Wall   10 hours...........         ** 6  14,767.7 m/0.417     6,634.7 m/0.417      398 m/0.165km\2\.
                                    Demolition for                                          km\2\.               km\2\.
                                    Waler Install.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Source: Kiewit 2021.
Notes:
* To determine underwater harassment zones, ensonified areas from the source were clipped along the shoreline using Geographical Information Systems
  (GIS).
** These activities will continue into the following construction years and the remaining construction days and activities will be included in a
  subsequent LOA. The construction days and activities represented in this table account ONLY for year 1 activities.
lf = linear feet; N/A = Not Applicable.
Proxy sources used were unattenuated SPLs.


                            Table 8--Calculated Distance and Areas of Level A and Level B Harassment for Non-Impulsive Noise
                                                        [Vibratory pile driving, rotary drilling]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                Level A harassment (PTS onset)        Level B harassment
                                                                                 Total    --------------------------------------------------------------
             Activity                     Purpose           Count and size     production     High frequency
                                                                                  days       cetaceans harbor     Phocid pinnipeds   Harbor porpoise and
                                                                                                 porpoise                                  phocids
--------------------------------------------------------------------------------------------------------------------------------------------------------
Rotary Drill.....................  Center Wall           38, 102-inch                  38  2.1 m/0.000014       1.3 m/0.000005       1,848 m/0.417
                                    Foundation Pile--     Borings.                          km\2\.               km\2\.               km\2\.
                                    Install Outer
                                    Casing.
Rotary Drill.....................  Center Wall           38, 102-inch                  38  8.9 m/0.000248       5.4 m/0.000091       1,848 m/0.417
                                    Foundation Pile--     Borings.                          km\2\.               km\2\.               km\2\.
                                    Pre-Drill Socket.
Rotary Drill.....................  Center Wall           38, 102-inch                  38  0.8 m/0.000002       0.5 m/0.000001       1,848 m/0.417
                                    Foundation Pile--     Borings.                          km\2\.               km\2\.               km\2\.
                                    Remove Outer Casing.
Rotary Drill.....................  Center Wall Leveling  18, 102-inch                  18  2.1 m/0.000014       1.3 m/0.000005       1,848 m/0.417
                                    Piles--Install        Borings.                          km\2\.               km\2\.               km\2\.
                                    Outer Casing.
Rotary Drill.....................  Center Wall Leveling  18, 102-inch                  18  8.9 m/0.000248       5.4 m/0.000091       1,848 m/0.417
                                    Piles--Pre-Drill      Borings.                          km\2\.               km\2\.               km\2\.
                                    Socket.
Rotary Drill.....................  Center Wall Leveling  18, 102-inch                  18  0.8 m/0.000002       0.5 m/0.000001       1,848 m/0.417
                                    Piles--Remove Outer   Borings.                          km\2\.               km\2\.               km\2\.
                                    Casing.
Rotary Drill.....................  Center Wall Access    38, 102-inch                  38  2.1 m/0.000014       1.3 m/0.000005       1,848 m/0.417
                                    Platform Support--    Borings.                          km\2\.               km\2\.               km\2\.
                                    Install Outer
                                    Casing.
Rotary Drill.....................  Center Wall Access    38, 102-inch                  38  8.9 m/0.000248       5.4 m/0.000091       1,848 m/0.417
                                    Platform Support--    Borings.                          km\2\.               km\2\.               km\2\.
                                    Pre-Drill Socket.
Rotary Drill.....................  Center Wall Access    38, 102-inch                  38  0.8 m/0.000002       0.5 m/0.000001       1,848 m/0.417
                                    Platform Support --   Borings.                          km\2\.               km\2\.               km\2\.
                                    Remove Outer Casing.
Vibratory Pile Driving...........  Tie-In to Existing    16, ** 28-inch Z-           ** 4  12.2 m/0.000454      5.0 m/0.000078       13,594 m/0.417
                                    West Closure Wall.    Shaped Sheets.                    km\2\.               km\2\.               km\2\.
Vibratory Pile Driving...........  Berth 11 End Wall     60, 28-inch Z-                 7  19.4 m/0.001041      8.0 m/0.0002 km\2\.  13,594 m/0.417
                                    Secant Pile Guide     Shaped Sheets.                    km\2\.                                    km\2\.
                                    Wall.
Vibratory Extraction.............  Remove P-310 West     238, 18-inch Flat             60  6.6 m/0.000136       2.7 m/0.000023       7,356 m/0.417
                                    Closure Wall.         Sheets.                           km\2\.               km\2\.               km\2\.
Vibratory Pile Driving...........  Install Sheet Piles   96, 28-inch Z-                12  19.4 m/0.001041      8.0 m/0.0002 km\2\.  13,594 m/0.417
                                    for Dry Dock 1        Shaped Sheets.                    km\2\.                                    km\2\.
                                    North Entrance and
                                    Temporary Cofferdam.
--------------------------------------------------------------------------------------------------------------------------------------------------------
** These activities will continue into the following construction years and the remaining construction days and activities will be included in a
  subsequent LOA. The construction days and activities represented in this table account ONLY for year 1 activities.
lf = linear feet; N/A = Not Applicable.
Proxy sources used were unattenuated SPLs.


[[Page 11879]]

Concurrent Activities
    Simultaneous use of pile drivers, hammers, and drills could result 
in increased SPLs and harassment zone sizes given the proximity of the 
component sites and the rules of decibel addition (see Table 9 below). 
Due to the relatively small size of the ROI, the use of a single DTH 
cluster drill or rock hammer would ensonify the entire ROI to the Level 
A harassment thresholds (PTS Onset) (refer to Table 7). Therefore, when 
this equipment is operated in conjunction with other noise generating 
equipment, there would be no change in the size of the harassment zone. 
The entire ROI would remain ensonified to the Level A harassment 
thresholds for the duration of the activity and there would be no Level 
B harassment zone. However, when DTH cluster drills or rock hammers are 
not in use, increased SPLs and harassment zone sizes within the ROI 
could result. Due to the large amount of bedrock excavation required 
for the construction of the multifunctional expansion of Dry Dock 1, 
the only scenario identified in which DTH cluster drills and/or rock 
hammers would not be in operation would be at the beginning of the 
project when two rotary drills could be used simultaneously (refer to 
Table 2).
    According to recent, project specific, guidance provided by NMFS to 
the Navy, when two noise sources have overlapping sound fields, there 
is potential for higher sound levels than for non-overlapping sources 
because the isopleth of one sound source encompasses the sound source 
of another isopleth. In such instances, the sources are considered 
additive and combined using the rules of decibel addition, presented in 
Table 9 below.

         Table 9--Adjustments for Sound Exposure Level Criterion
------------------------------------------------------------------------
                                                       Adjustments to
                               Difference in sound   specifications for
        Source types           level (at specified   Level A harassment
                                     meters)             RMS/SELss*
                                                        calculations
------------------------------------------------------------------------
Non-impulsive, continuous/    0 or 1 dB...........  Add 3 dB to the
 Non-impulsive, continuous                           highest sound level
 OR Impulsive source                                 (at specified
 (multiple strikes per                               meters) AND adjust
 second)/Impulsive source                            number of piles per
 (multiple strikes per                               day to account for
 second.                                             overlap (space and
                                                     time).
                              2 or 3 dB...........  Add 2 dB to the
                                                     highest sound level
                                                     (at specified
                                                     meters) AND adjust
                                                     number of piles per
                                                     day to account for
                                                     overlap (space and
                                                     time).
                              4 to 9 dB...........  Add 1 dB to the
                                                     highest sound level
                                                     (at specified
                                                     meters) AND adjust
                                                     number of piles per
                                                     day to account for
                                                     overlap (space and
                                                     time).
                              10 dB or more         Add 0 dB to the
                                                     highest sound level
                                                     (at specified
                                                     meters) AND adjust
                                                     number of piles per
                                                     day to account for
                                                     overlap (space and
                                                     time).
------------------------------------------------------------------------
* RMS level for vibratory pile driving/rotary hammer and single strike
  SEL (SELss) level for DTH/rock hammer.

    For simultaneous usage of three or more continuous sound sources, 
the three overlapping sources with the highest sound source levels are 
identified. Of the three highest sound source levels, the lower two are 
combined using the above rules, then the combination of the lower two 
is combined with the highest of the three. For example, with 
overlapping isopleths from 24-, 36-, and 42-inch diameter steel pipe 
piles with sound source levels of 161, 167, and 168 dB RMS 
respectively, the 24- and 36-inch would be added together; given that 
167-161 = 6 dB, then 1 dB is added to the highest of the two sound 
source levels (167 dB), for a combined noise level of 168 dB. Next, the 
newly calculated 168 dB is added to the 42-inch steel pile with sound 
source levels of 168 dB. Since 168-168 = 0 dB, 3 dB is added to the 
highest value, or 171 dB in total for the combination of 24-, 36-, and 
42-inch steel pipe piles (NMFS, 2021 unpublished). By using this 
method, a revised proxy source for Level A and Level B analysis was 
determined for the use of two, 102-inch diameter rotary drills. The 
revised proxy value is presented in Table 10 and the resulting 
harassment zones are summarized in Table 11 (depicted in Figure 6-13 in 
the Navy's application).

  Table 10--Revised Proxy Values for Simultaneous Use of Non-Impulsive
                                 Sources
------------------------------------------------------------------------
 
------------------------------------------------------------------------
Equipment                                                   Rotary drill
------------------------------------------------------------------------
                                                  RMS                154
Rotary Drill......................                154                157
------------------------------------------------------------------------


   Table 11--Level A and Level B Harassment Zones Resulting From the Simultaneous Use of Two, 102-in Diameter
                                                  Rotary Drill
----------------------------------------------------------------------------------------------------------------
                                                Level A harassment (PTS Onset)              Level B harassment
                                      --------------------------------------------------------------------------
                                           Harbor porpoise                                 Harbor porpoise and
      Multiple source  scenario           distance to 155 dB    Phocids distance to 185  phocids distance to 120
                                        SELcum threshold/area     dB SELcum threshold/   dB (DTH) threshold/area
                                          of harassment zone    area of harassment zone     of harassment zone
----------------------------------------------------------------------------------------------------------------
2 Rotary Drills......................  23.6 m/0.002 km\2\.....  9.7 m/0.0002 km\2\.....  2,929 m/0.417 km\2\.
----------------------------------------------------------------------------------------------------------------


[[Page 11880]]

Marine Mammal Occurrence and Take Calculation and Estimation

    In this section we provide the information about the presence, 
density, or group dynamics of marine mammals that will inform the take 
calculations. Potential exposures to impact pile and vibratory pile 
driving, rotary drilling, DTH, and rock hammering noise for each 
acoustic threshold were estimated using marine mammal density estimates 
(N) from the Navy Marine Species Density Database (NMSDD) (Navy 2017) 
or from monitoring reports from the Berth 11 Waterfront Improvements 
and P-310 construction projects. Specifically, where monitoring data 
specific to the project area were available, they were used, and the 
NMSDD data were used when there were no monitoring data available. The 
take estimate was determined using the following equation take estimate 
= N * days of activity * area of harassment. The pile type, size, and 
installation method that produce the largest zone of influence (ZOI) 
were used to estimate exposure of marine mammals to noise impacts. We 
describe how the information provided above is brought together to 
produce a quantitative take estimate in the species sections below.
Harbor Porpoise
    Harbor porpoises may be present in the proposed project area during 
spring, summer, and fall, from April to December. Based on density data 
from the Navy Marine Species Density Database, their presence is 
highest in spring, decreases in summer, and slightly increases in fall. 
During previous monitoring of construction projects in the area, three 
harbor porpoise were sighted between April and December of 2017; two 
harbor porpoise were sighted in early August of 2018; and one harbor 
porpoise was sighted in 2020 (Cianbro 2018a, b; Navy 2019; NAVFAC 
2021). Using the 2017 and 2018 data from construction monitoring for 
the Berth 11 Waterfront Improvements project, the density of harbor 
porpoise for the largest harassment zone was determined to be 0.04/
km\2\.
    Estimated take was calculated by density * harassment zone * days 
for each activity (see Table 12). Note that where the Level A 
harassment zone is as large as the Level B harassment zone and fills 
the entire ensonified area, the enumerated takes in the Level A 
harassment column may be in the form of Level A harassment and/or Level 
B harassment.

   Table 12--Calculated Proposed Take by Level A and Level B Harassment of Harbor Porpoise by Project Activity
----------------------------------------------------------------------------------------------------------------
                                                   Level A                                Level B
                                                  harassment   Number of     Take by     harassment    Take by
         Project activity             Density        zone         days       Level A        zone       Level B
                                                   (km\2\)                  harassment    (km\2\)     harassment
----------------------------------------------------------------------------------------------------------------
Center Wall--Install Foundation:           0.04        0.417          247            4        0.417            0
 38 drilled shafts: Cluster drill
 DTH (Drill) 78-inch diameter
 casing...........................
Center Wall--Install Diving Board          0.04        0.417          117            2        0.417            0
 Shafts: 18 drilled shafts:
 Cluster drill DTH (Drill) 78-inch
 diameter socket..................
Center Wall--Access Platform               0.04        0.417          133            2        0.417            0
 Support: 38 drilled shafts:
 Cluster Drill DTH (Drill) 78-inch
 outer casing.....................
Mechanical Rock Excavation,                0.04        0.417           77            1        0.165            0
 Hydraulic rock hammering (985 cy)
Remove Shutter Panels: 112 panels,         0.04        0.417           56            1        0.165            0
 Demolish shutter panels,
 Hydraulic rock hammering.........
Mechanical Rock Removal at Basin           0.04        0.417          100            2        0.165            0
 Floor: Excavate Bedrock,
 Hydraulic rock hammering.........
Mechanical Rock at Abutment: Drill         0.04        0.417          183            3        0.417            0
 365 rock borings (1,220 cy), 42-
 inch diameter casing, Mono-hammer
 DTH..............................
Center Wall--Install Foundation:           0.04      0.00001           38            0        0.417            1
 38 drilled shafts: Rotary Drill
 (Install) 102-inch diameter outer
 casing...........................
Center Wall--Install Foundation:           0.04      0.00001           38            0        0.417            1
 38 drilled shafts: Rotary Drill
 (Pre-drill) 102-inch diameter
 socket,..........................
Center Wall--Install Foundation:           0.04      0.00001           38            0        0.417            1
 38 drilled shafts: Rotary Drill
 (Remove) 102-inch outer casing...
Center Wall--Access Platform               0.04      0.00001           38            0        0.417            1
 Support: 38 drilled shafts:
 Rotary Drill (Install) 102-inch
 diameter outer casing............
Center Wall--Access Platform               0.04      0.00001           38            0        0.417            1
 Support: 38 drilled shafts:
 Rotary Drill (Pre-drill) 102-inch
 diameter socket..................
Center Wall--Access Platform               0.04    0.0000002           38            0        0.417            1
 Support: 38 drilled shafts:
 Rotary Drill (Remove) 102-inch
 outer casing,....................
Remove Wall: 238 sheet piles, 18-          0.04     0.000136           60            0        0.417            1
 inch wide flatwebbed, Vibratory
 Extraction.......................
Mechanical Rock Removal at Basin           0.04     0.048109           82            0        0.417            1
 Floor: Drill 2,201 relief holes,
 4-6 holes, Mono-hammer DTH,......
Drill Tremie Ties Downs: Drill 100         0.04       0.0303           52            0        0.417            1
 rock anchors, 9-inch holes, Mono-
 hammer DTH.......................
                                   -----------------------------------------------------------------------------
    Total Estimated Take..........  ...........  ...........  ...........           15  ...........            9
----------------------------------------------------------------------------------------------------------------

    In summary, we estimate that up to 15 takes in the form of Level A 
harassment and/or Level B harassment could occur during DTH excavation 
(DTH mono-hammer and cluster drill), impact pile driving, and rock 
hammering activities. In addition, DTH mono-hammer excavation could 
result in 2 takes by Level B harassment and vibratory installing/
extracting and rotary drilling activities could result in 7 takes by 
Level B harassment (Table 12).
Harbor Seal
    Harbor seals may be present year-round in the project vicinity, 
with constant densities throughout the year. Harbor seals are the most 
common pinniped in the Piscataqua River near the Shipyard. Harbor seal 
sightings were recorded during monthly surveys conducted in 2017 and 
2018 (NAVFAC Mid-Atlantic 2018, 2019b) as well as during Berth 11 and 
P-310 construction monitoring in 2017, 2018, 2020 and 2021 (Cianbro 
2018a, b; Navy 2019; Stantec 2020, Stantec 2021). Estimated take by 
Level B harassment has been calculated by multiplying the average 
number of harbor seals sighted per day from May 2020 through October 
2021 by the number of actual in-water

[[Page 11881]]

construction days (375 days (159 during P-310 year 1 and 216 during P-
310 year 2). Over the course of this time period, there have been 1,023 
harbor seal observations equating to equating to 3 harbor seal 
sightings per day. Initially, takes were calculated for Level A and 
Level B harassment for harbor seals where the density of animals (2.48 
harbor seals/km\2\, rounded to 3) was multiplied by the harassment zone 
and the number of days per construction activity. However, using that 
method produced take numbers for Level B harassment that were lower 
than the number of harbor seals that has been previously observed in 
the Navy's monitoring reports. Therefore, NMFS is proposing (and the 
Navy agrees), to increase the take by Level B harassment to more 
accurately reflect harbor seal observations in the monitoring reports, 
by using the value of three harbor seals a day multiplied by the total 
number of construction days resulting in 1,125 takes by Level B 
harassment proposed for authorization. Take by Level A harassment of 
1,269 harbor seals is shown in Table 13 below. Note that where the 
Level A harassment zone is as large as the Level B harassment zone and 
fills the entire ensonified area, the enumerated takes in the Level A 
harassment column may be in the form of Level A harassment and/or Level 
B harassment. The proposed takes by Level B harassment were not 
included in Table 13 as they were calculated by a different method.

           Table 13--Calculated Proposed Take by Level A Harassment of Harbor Seal by Project Activity
----------------------------------------------------------------------------------------------------------------
                                                                      Level A
                Project activity                   Harbor seals     harassment    Number of days   Take by Level
                                                      density      zone (km\2\)                    A harassment
----------------------------------------------------------------------------------------------------------------
Center Wall--Install Foundation: 38 drilled                    3           0.417             247             309
 shafts: Cluster drill DTH (Drill) 78-inch
 diameter casing................................
Center Wall--Install Diving Board Shafts: 18                   3           0.417             117             146
 drilled shafts: Cluster drill DTH (Drill) 78-
 inch diameter socket...........................
Center Wall--Access Platform Support: 38 drilled               3           0.417             133             166
 shafts: Cluster Drill DTH (Drill) 78-inch outer
 casing.........................................
Center Wall--Temp Launching Piles: 6 drilled                   3           0.417               6               8
 shafts: 42-inch diameter shaft, Mono-hammer DTH
Center Wall Tie Downs: 36 Rock Anchors                         3           0.023              18               1
 (Install): 9-inch diameter holes, Mono-hammer
 DTH............................................
Center Wall--Access Platform Tie Downs: 18 Rock                3           0.023               9               1
 Anchors (Install): 9-inch diameter holes, Mono-
 hammer DTH.....................................
Center Wall-Install Tie-In to Existing West                    3           0.201               4               2
 Closure Wall: 16 sheet piles: 28-inch wide Z-
 shaped sheets--IMPACT Install..................
Berth 11 End Wall--Install Secant Pile Guide                   3           0.417               7               8
 Wall: 60 sheets piles: 28-inch wide Z-shaped
 sheets--IMPACT Install.........................
Berth 1--Remove Granite Block Quay Wall: 610 cy,               3           0.417              10              13
 Granite block demo, Hydraulic Rock hammering...
P310 West Closure Wall--Mechanical Rock                        3           0.417              77              96
 Excavation: 985 cy, Excavated bedrock,
 Hydraulic rock hammering.......................
P310 West Closure Wall--Mechanical Rock                        3           0.015              20               1
 Excavation: Drill 500 relief holes, 4-6 inch
 holes, Mono-hammer DTH.........................
P310 West Closure Wall--Mechanical Rock                        3           0.417              24              30
 Excavation: Drill 46 rock borings (50 cy), 42-
 inch diameter casing, Mono-hammer DTH..........
West Closure well--Berth 11 Abutment- Install                  3           0.417              28              35
 Piles: Drill 28 shafts, 42-inch diameter
 casing, Mono-hammer DTH........................
Berth 11--Remove Shutter Panels: 112 panels,                   3           0.417              56              70
 Demolish shutter panels, Hydraulic rock
 hammering......................................
Berth 11 Face--Mechanical Rock Removal at Basin                3           0.417             100             125
 Floor: 3,500 cy, Excavate Bedrock, Hydraulic
 rock hammering.................................
Berth 11 Face--Mechanical Rock Removal at Basin                3           0.015              82               4
 Floor: Drill 2,201 relief holes, 4-6 holes,
 Mono-hammer DTH................................
Berth 11 Face--Mechanical Rock at Abutment:                    3           0.417             183             229
 Drill 365 rock borings (1,220 cy), 42-inch
 diameter casing, Mono-hammer DTH...............
Dry Dock 1 North Entrances--Install Temporary                  3           0.365              12              13
 Cofferdam: Install 96 sheet piles, 28-inch wide
 Z-shaped sheets, IMPACT Install................
Berth 1--Remove sheet piles: Remove 12 sheet                   3           0.417               3               4
 piles, 25-inch wide Z-shaped sheets, Hydraulic
 rock hammering.................................
Berth 1 Top of Wall--Demolition for Waler                      3           0.417               6               8
 Installation: 30 lf, Mechanical concrete
 demolition, Hydraulic rock hammering...........
                                                 ---------------------------------------------------------------
    Total Estimated Take........................  ..............  ..............  ..............           1,269
----------------------------------------------------------------------------------------------------------------

Gray Seal
    Gray seals may be present year-round in the project vicinity, with 
constant densities throughout the year. Gray seals are less common in 
the Piscataqua River than the harbor seal. Sightings of gray seals were 
recorded during P-310 construction monitoring in 2020 and 2021 (Stantec 
2020; Stantec 2021). Estimated take by Level B harassment has been 
calculated by multiplying the average number of gray seal observations 
per day from May 2020 through October 2021 (47 during year 1 P-310 
monitoring and 9 during year 2 P-310 monitoring (to date)) over the 
course of 337 monitoring days (Stantec 2020; 2021). Over the course of 
this time period, there have been 56 gray seal observations equating to 
equating to 0.2 gray seal sightings per day. Initially, takes were 
calculated for Level A and Level B harassment for gray seals where

[[Page 11882]]

the density was multiplied by the harassment zone and the number of 
days per construction activity. However, using that method produced 
take numbers for Level B harassment that were fewer than the number of 
gray seals that has been previously observed in the Navy's monitoring 
reports. Therefore, NMFS is proposing (and the Navy agrees), to 
increase the take by Level B harassment to more accurately reflect gray 
seal observations in the monitoring reports, by using the value of 0.2 
gray seals multiplied by the total number of construction days 
resulting in 75 takes by Level B harassment proposed for authorization. 
Initially takes were calculated for Level A and Level B harassment for 
gray seals in a similar manner where takes were determined by 
individual activity. However, NMFS is proposing (and Navy agrees) to 
increase the take by Level B harassment by using the value of 0.2 gray 
seals which were then multiplied by the number of total construction 
days resulting in 75 takes by Level B harassment proposed for 
authorization. Take by Level A harassment of 85 gray seals is shown in 
Table 14 below. Note that where the Level A harassment zone is as large 
as the Level B harassment zone and fills the entire ensonified area, 
the enumerated takes in the Level A harassment column may be in the 
form of Level A harassment and/or Level B harassment. The proposed 
takes by Level B harassment were not included in Table 14 as they were 
calculated by a different method.

            Table 14--Calculated Proposed Take by Level A Harassment of Gray Seal by Project Activity
----------------------------------------------------------------------------------------------------------------
                                                                      Level A
                Project activity                     Gray seal      harassment    Number of days   Take by Level
                                                      density      zone (km\2\)                    A harassment
----------------------------------------------------------------------------------------------------------------
Center Wall--Install Foundation: 38 drilled                  0.2           0.417             247              21
 shafts: Cluster drill DTH (Drill) 78-inch
 diameter casing................................
Center Wall--Install Diving Board Shafts: 18                 0.2           0.417             117              10
 drilled shafts: Cluster drill DTH (Drill) 78-
 inch diameter socket...........................
Center Wall--Access Platform Support: 38 drilled             0.2           0.417             133              11
 shafts: Cluster Drill DTH (Drill) 78-inch outer
 casing.........................................
Center Wall--Temp Launching Piles: 6 drilled                 0.2           0.417               6               1
 shafts: 42-inch diameter shaft, Mono-hammer DTH
Berth 11 End Wall--Install Secant Pile Guide                 0.2           0.417               7               1
 Wall: 60 sheets piles: 28-inch wide Z-shaped
 sheets--IMPACT Install.........................
Berth 1--Remove Granite Block Quay Wall: 610 cy,             0.2           0.417              10               1
 Granite block demo, Hydraulic Rock hammering...
P310 West Closure Wall--Mechanical Rock                      0.2           0.417              77               6
 Excavation: 985 cy, Excavated bedrock,
 Hydraulic rock hammering.......................
P310 West Closure Wall--Mechanical Rock                      0.2           0.417              24               2
 Excavation: Drill 19 rock borings (50 cy), 42-
 inch diameter casing, Mono-hammer DTH..........
West Closure well--Berth 11 Abutment- Install                0.2           0.417              28               2
 Piles: Drill 28 shafts, 42-inch diameter
 casing, Mono-hammer DTH........................
Berth 11--Remove Shutter Panels: 112 panels,                 0.2           0.417              56               5
 Demolish shutter panels, Hydraulic rock
 hammering......................................
Berth 11 Face--Mechanical Rock Removal at Basin              0.2           0.417               3               8
 Floor: 1,020 cy, Excavate Bedrock, Hydraulic
 rock hammering.................................
Berth 11 Face--Mechanical Rock at Abutment:                  0.2           0.417              24              15
 Drill 192 rock borings (610 cy), 42-inch
 diameter casing, Mono-hammer DTH...............
Dry Dock 1 North Entrances--Install Temporary                0.2           0.365              12               1
 Cofferdam: Install 96 sheet piles, 28-inch wide
 Z-shaped sheets, IMPACT Install................
Berth 1 Top of Wall--Demolition for Waler                    0.2           0.417               6               1
 Installation: 30 lf, Mechanical concrete
 demolition, Hydraulic rock hammering...........
                                                 ---------------------------------------------------------------
    Total Estimated Take........................  ..............  ..............  ..............              85
----------------------------------------------------------------------------------------------------------------

Hooded Seal
    Hooded seals may be present in the project vicinity from January 
through May, though their exact seasonal densities are unknown. In 
general, hooded seals are much rarer than the harbor seal and gray seal 
in the Piscataqua River. One take per month from January to May from 
Level B harassment of a hooded seal for the Berth 11 Waterfront 
Improvements Construction project (NMFS 2018b) and for Year 1 
construction activities for Dry Dock 1 (NMFS, 2019) was previously 
authorized. To date, the monitoring for that project and for the 
density surveys have not recorded a sighting of hooded seal in the 
project area (Cianbro 2018a, b; NAVFAC Mid-Atlantic 2018, 2019b; Navy 
2019; Stantec 2020; Stantec 2021). In order to guard against 
unauthorized take, the Navy is requesting and NMFS is proposing one 
take by Level B harassment of hooded seal per month (between the months 
of January and May) resulting in five total takes of Level B 
harassment. No take by Level A harassment is anticipated or proposed 
for authorization.
Harp Seal
    Harp seals may be present in the project vicinity January through 
May. In general, harp seals are much rarer than the harbor seal and 
gray seal in the Piscataqua River. As discussed above for hooded seals, 
one take by Level B harassment during each month of construction for 
the Berth 11 Waterfront Improvements Project (NMFS 2018b) and for year 
1 construction activities for Dry Dock 1 (NMFS, 2019) was previously 
authorized. The monitoring for the Berth 11 Waterfront Improvements 
Construction and P-310 projects did not record any sightings of harp 
seal in the project area (Cianbro 2018a, b; NAVFAC Mid-Atlantic 2018, 
2019b; Navy 2019; Stantec 2020; Stantec 2021). However, it should be 
noted that two harp seals (one on 5/12/2020 and one on 5/14/2020) were 
observed when pile driving activities were not

[[Page 11883]]

occurring (Stantec 2020). In order to guard against unauthorized take, 
the Navy is requesting and NMFS is proposing one take by Level B 
harassment of harp seal per month (between the months of January and 
May) resulting in five total takes of Level B harassment. No take by 
Level A harassment is anticipated or proposed for authorization.
    Table 15 below summarizes the authorized take for all the species 
described above as a percentage of stock abundance.

                      Table 15--Proposed Take Estimates as a Percentage of Stock Abundance
----------------------------------------------------------------------------------------------------------------
                                                 Proposed Level  Proposed Level
           Species               Stock (NEST)     A  harassment   B  harassment          Percent of stock
----------------------------------------------------------------------------------------------------------------
Harbor porpoise..............  Gulf of Maine/                15               9  Less than 1 percent.
                                Bay of Fundy
                                (95,543).
Harbor seal..................  Western North              1,269           1,125  Less than 3 percent.
                                Atlantic
                                (61,336).
Gray seal....................  Western North                 85              75  Less than 1 percent.
                                Atlantic
                                (451,600).
Hooded seal..................  Western North                  0               5  Less than 1 percent.
                                Atlantic
                                (593,500).
Harp seal....................  Western North                  0               5  Less than 1 percent.
                                Atlantic (7.6
                                million).
----------------------------------------------------------------------------------------------------------------

Proposed Mitigation

    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, 
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, we carefully consider 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, impact on 
operations, and, in the case of a military readiness activity, 
personnel safety, practicality of implementation, and impact on the 
effectiveness of the military readiness activity.
    Based on our evaluation of the applicant's proposed measures, as 
well as other measures considered by NMFS, NMFS has preliminarily 
determined that the proposed mitigation measures provide the means 
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.

General

    The Navy shall follow mitigation procedures as described below. In 
general, if poor environmental conditions restrict full visibility of 
the shutdown zone, pile driving activities would be delayed.

Training

    The Navy shall ensure that construction supervisors and crews, the 
monitoring team, and relevant Navy staff are trained and prior to the 
start of construction activity, so that responsibilities, communication 
procedures, monitoring protocols, and operational procedures are 
clearly understood. New personnel joining during the project shall be 
trained prior to commencing work.

Avoiding Direct Physical Interaction

    The Navy shall avoid direct physical interaction with marine 
mammals during construction activity. If a marine mammal comes within 
10 m of such activity, operations shall cease and vessels will reduce 
speed to the minimum level required to maintain steerage and safe 
working conditions, as necessary to avoid direct physical interaction.

Shutdown Zones

    The Navy 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 will vary based on the activity type and marine 
mammal hearing group (Table 16).

               Table 16--Pile Driving Shutdown Zone and Monitoring Zones During Project Activities
----------------------------------------------------------------------------------------------------------------
                                                                    Shutdown zone (m)               Level B
                                                           -----------------------------------   harassment \1\
             P-381 Year 1 activity description                                                  monitoring zone
                                                             Harbor porpoise       Phocids            (m)
----------------------------------------------------------------------------------------------------------------
78-inch cluster drill.....................................            \2\ 200          \2\ 50               ROI.
DTH monohammer--42-inch...................................            \2\ 200          \2\ 50               ROI.
DTH monohammer--9-inch Center wall tie downs..............            \2\ 200          \2\ 50               ROI.
DTH monohammer--9-inch tremie tie-downs...................            \2\ 200          \2\ 50               ROI.
DTH monohammer--4-6-inch (500)............................            \2\ 200          \2\ 50               ROI.
Impact install of sheet piles (16) West Closure Wall Tie-             \2\ 200          \2\ 50               ROI.
 in.......................................................
Impact install of sheet piles (60) Secant pile guide wall;            \2\ 200          \2\ 50               ROI.
 (96) temporary coffer dam................................

[[Page 11884]]

 
Rock hammering--all durations.............................            \2\ 200          \2\ 50               ROI.
Rotary drilling--Install 102-inch casing..................                 10              10               ROI.
Rotary drilling--Predrill 102-inch socket.................                 10              10               ROI.
Rotary drilling--Remove 102-inch casing...................                 10              10               ROI.
Vibratory pile driving (16) 28-inch sheets................                 20              10               ROI.
Vibratory pile driving (60) and (96) 28-inch sheets.......                 20              10               ROI.
Vibratory extraction (238) 28-inch sheets.................                 10              10               ROI.
----------------------------------------------------------------------------------------------------------------
Notes:
\1\ In instances where the harassment zone is larger than the ROI, the entire ROI is indicated as the limit of
  monitoring.
\2\ Reduced Monitoring area distance negotiated with NMFS.
Key: ROI--region of influence.

Soft Start

    The Navy shall use soft start techniques when impact pile driving. 
Soft start requires contractors 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 would 
occur. A soft start will 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. Soft start is not 
required during vibratory pile driving activities.

Bubble Curtain

    A bubble curtain shall be installed across any openings at the 
entrance of super flood basin to attenuate sound for the sound sources 
that encompass the entire ROI. The Navy will record hydroacoustic 
measurements inside and outside of the bubble curtain. Should the 
results of the recordings inside the bubble curtain show that 
thresholds are not being exceeded by the activity occurring, that upon 
review of the data by NMFS, Navy may discontinue use of the bubble 
curtain for those activities that are not actually exceeding 
thresholds.
    Based on our evaluation of the applicant's planned measures, NMFS 
has preliminarily determined that the mitigation measures provide the 
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.

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 in the 
action area. Effective reporting is critical both to compliance as well 
as for 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:
    [ssquf] Occurrence of marine mammal species or stocks in the area 
in which take is anticipated (e.g., presence, abundance, distribution, 
density);
    [ssquf] 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);
    [ssquf] Individual marine mammal responses (behavioral or 
physiological) to acoustic stressors (acute, chronic, or cumulative), 
other stressors, or cumulative impacts from multiple stressors;
    [ssquf] How anticipated responses to stressors impact either: (1) 
Long-term fitness and survival of individual marine mammals; or (2) 
populations, species, or stocks;
    [ssquf] Effects on marine mammal habitat (e.g., marine mammal prey 
species, acoustic habitat, or other important physical components of 
marine mammal habitat); and
    [ssquf] Mitigation and monitoring effectiveness.
    The Navy shall submit a Marine Mammal Monitoring Plan to NMFS for 
approval in advance of the start of construction.

Monitoring Zones

    The Navy shall conduct monitoring to include the area within the 
Level B harassment zones (areas where SPLs are equal to or exceed the 
160 dB RMS threshold for impact driving and the 120 dB RMS threshold 
during vibratory pile driving) (see Table 16 above). These monitoring 
zones provide utility for monitoring conducted for mitigation purposes 
(i.e., shutdown zone monitoring) by establishing monitoring protocols 
for areas adjacent to the shutdown zones. Monitoring of the disturbance 
zones enables observers to be aware of and communicate the presence of 
marine mammals in the project area, but outside the shutdown zone, and 
thus prepare for potential shutdowns of activity.

Visual Monitoring

    Monitoring shall take place from 30 minutes (min) prior to 
initiation of pile driving activity (i.e., pre-start clearance 
monitoring) through 30 min post-completion of pile driving activity. If 
a marine mammal is observed entering or within the shutdown zones, pile 
driving shall be delayed or halted. If pile driving 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 or 15 min have passed 
without re-detection of the animal. Pile driving activity shall be 
halted upon observation of either 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

[[Page 11885]]

met, entering or within the disturbance zone.

Protected Species Observer (PSO) Monitoring Requirements and Locations

    PSOs shall be responsible for monitoring, the shutdown zones, the 
disturbance zones and the pre-clearance zones, as well as effectively 
documenting Level A and B harassment take. As described in more detail 
in the Reporting section below, they shall also (1) document the 
frequency at which marine mammals are present in the project area, (2) 
document behavior and group composition, (3) record all construction 
activities, and (4) document observed reactions (changes in behavior or 
movement) of marine mammals during each sighting. The PSOs shall 
monitor for marine mammals during all in-water pile activities 
associated with the project. The Navy shall monitor the project area to 
the extent possible based on the required number of PSOs, required 
monitoring locations, and environmental conditions. Visual monitoring 
shall be conducted by three PSOs. It is assumed that three PSOs shall 
be located on boats, docks, or piers sufficient to monitor the 
respective ROIs given the abundance of suitable vantage points (see 
Figure 11-1 of the application). The PSOs must record all observations 
of marine mammals, regardless of distance from the pile being driven.
    In addition, PSOs shall work in shifts lasting no longer than 4 hrs 
with at least a 1-hr break between shifts and will not perform duties 
as a PSO for more than 12 hrs in a 24[hyphen]hr period (to reduce PSO 
fatigue).
    Monitoring of pile driving shall be conducted by qualified, PSOs. 
The Navy shall adhere to the following conditions when selecting PSOs:
    [ssquf] PSOs must be independent (i.e., not construction personnel) 
and have no other assigned tasks during monitoring periods;
    [ssquf] At least one PSO must have prior experience performing the 
duties of a PSO during construction activities pursuant to a NMFS-
issued incidental take authorization;
    [ssquf] Other PSOs may substitute other relevant experience, 
education (degree in biological science or related field), or training;
    [ssquf] Where a team of three PSOs are required, a lead observer or 
monitoring coordinator shall be designated. The lead observer must have 
prior experience performing the duties of a PSO during construction 
activity pursuant to a NMFS-issued incidental take authorization; and
    [ssquf] PSOs must be approved by NMFS prior to beginning any 
activity subject to this rule.
    The Navy will ensure that the PSOs have the following additional 
qualifications:
    [ssquf] Visual acuity in both eyes (correction is permissible) 
sufficient for discernment of moving targets at the water's surface 
with ability to estimate target size and distance; use of binoculars 
may be necessary to correctly identify the target;
    [ssquf] Experience and ability to conduct field observations and 
collect data according to assigned protocols;
    [ssquf] Experience or training in the field identification of 
marine mammals, including the identification of behaviors;
    [ssquf] Sufficient training, orientation, or experience with the 
construction operation to provide for personal safety during 
observations;
    [ssquf] 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
    [ssquf] 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.

Hydroacoustic Monitoring

    The Navy shall conduct a sound source verification (SSV) study for 
all pile types and will follow accepted methodological standards to 
achieve their objectives. The Navy shall submit an acoustic monitoring 
plan to NMFS for approval prior to the start of construction. The Navy 
will collect and evaluate acoustic sound record levels for 10 percent 
of the new rotary drilling, DTH excavation (DTH mono-hammer and cluster 
drill), and rock hammering activities conducted as part of P-381 (Table 
15). Hydrophones would be placed at locations 10 m (33 ft) from the 
noise source and, where the potential for Level A harassment exists, at 
a second representative monitoring location at an intermediate distance 
between the cetacean and phocid shutdown zones. For the 10 percent of 
rotary drilling, DTH excavation (DTH mono-hammer and cluster drill), 
and rock hammering events acoustically measured, 100 percent of the 
data will be analyzed.
    At a minimum, the methodology includes:
    [ssquf] For underwater recordings, a stationary hydrophone system 
with the ability to measure SPLs will be placed in accordance with NMFS 
most recent guidance for the collection of source levels.
    [ssquf] Hydroacoustic monitoring will be conducted for 10 percent 
of each different type of activity not previously monitored as part of 
P-310 (Table 15). Monitoring will occur from the same locations 
approved by NMFS for P-310 construction activities. The resulting data 
set will be analyzed to examine and confirm sound pressure levels and 
rates of transmission loss for each separate in-water construction 
activity. With NMFS concurrence, these metrics will be used to 
recalculate the limits of shutdown and Level B (Behavioral) harassment 
zones, and to make corresponding adjustments in marine mammal 
monitoring of these zones for use in the forthcoming rulemaking/LOA 
application. Hydrophones will be placed in the same manner as for P-310 
construction activities. Locations of hydroacoustic recordings will be 
collected via GPS. A depth sounder and/or weighted tape measure will be 
used to determine the depth of the water. The hydrophone will be 
attached to a-weighted nylon cord to maintain a constant depth and 
distance from the pile/drill/hammer location. The nylon cord or chain 
will be attached to a float or tied to a static line.
    [ssquf] Each hydrophone (underwater) will be calibrated at the 
start of each action and will be checked frequently to the applicable 
standards of the hydrophone manufacturer.
    [ssquf] For each monitored location, a single hydrophone will be 
suspended midway in the water column in order to evaluate site-specific 
attenuation and propagation characteristics that may be present 
throughout the water column.
    [ssquf] Environmental data will 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 contribute to influencing the 
airborne and underwater sound levels (e.g., aircraft, boats, etc.).
    [ssquf] The chief inspector will supply the acoustics specialist 
with the substrate composition, hammer/drill model and size, hammer/
drill energy settings, depth of drilling, and boring rates and any 
changes to those settings during the monitoring.
    [ssquf] For acoustically monitored construction activities, data 
from the continuous monitoring locations will be post-processed to 
obtain the following sound measures:

[[Page 11886]]

    [cir] Maximum peak pressure level recorded for all activities, 
expressed in dB re 1 [mu]Pa. This maximum value will originate from the 
phase of drilling/hammering during which drill/hammer energy was also 
at maximum (referred to as Level 4).
    [cir] From all activities occurring during the Level 4 phase these 
additional measures will be made, as appropriate:

[ssquf] Mean, median, minimum, and maximum RMS pressure level in (dB re 
1 [mu]Pa)
[ssquf] mean duration of a pile strike (based on the 90 percent energy 
criterion)
[ssquf] number of hammer strikes
[ssquf] mean, median, minimum, and maximum single strike SEL (dB re 
[mu]Pa\2\ sec)

    [cir] Cumulative SEL as defined by the mean single strike SEL + 
10*log (number of hammer strikes) (dB re [mu]Pa\2\ sec).
    [cir] Median integration time used to calculate SPL RMS.
    [cir] A frequency spectrum (pressure spectral density) (dB re 
[mu]Pa\2\ per Hz) based on the average of up to eight successive 
strikes with similar sound. Spectral resolution will be 1 Hz, and the 
spectrum will cover nominal range from 7 Hz to 20 kHz.
    [cir] Finally, the cumulative SEL will 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 (dB re [mu]Pa\2\ sec).

                                   Table 17--Hydroacoustic Monitoring Summary
----------------------------------------------------------------------------------------------------------------
                                                                                                      Number
               Size                             Count                         Activity               monitored
----------------------------------------------------------------------------------------------------------------
102-inch.........................  94.............................  Rotary Drill................               9
78-inch..........................  94.............................  DTH Cluster Drill...........               9
42-inch..........................  445............................  DTH Mono-hammer.............              10
9-inch...........................  154............................  DTH Mono-hammer.............              10
4 to 6-inch......................  2,701..........................  DTH Mono-hammer.............              10
NA...............................  252 days.......................  Rock Hammering..............              10
----------------------------------------------------------------------------------------------------------------

Marine Mammal Monitoring Reporting

    The Navy shall submit a draft report to NMFS within 90 calendar 
days of the completion of monitoring or 60 calendar days prior to the 
requested issuance of any subsequent IHA for construction activity at 
the same location, whichever comes first. The report will detail the 
monitoring protocol and summarize the data recorded during monitoring. 
The final report must be prepared and submitted within 30 days 
following resolution of any NMFS comments on the draft report. If no 
comments are received from NMFS within 30 days of receipt of the draft 
report, the report shall be considered final. If comments are received, 
a final report addressing NMFS comments must be submitted within 30 
days after receipt of comments. All draft and final marine mammal 
monitoring reports must be submitted to 
[email protected] and [email protected]. The report 
must contain the following informational elements, at minimum, (and be 
included in the Marine Mammal Monitoring Plan), including:
    [ssquf] Dates and times (begin and end) of all marine mammal 
monitoring;
    [ssquf] Construction activities occurring during each daily 
observation period, including:
    [cir] How many and what type of piles were driven and by what 
method (e.g., impact or vibratory); and
    [cir] Total duration of driving time for each pile (vibratory 
driving) and number of strikes for each pile (impact driving);
    [ssquf] PSO locations during marine mammal monitoring;
    [ssquf] 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;
    [ssquf] Upon observation of a marine mammal, the following 
information:
    [cir] PSO who sighted the animal and PSO location and activity at 
time of sighting;
    [cir] Time of sighting;
    [cir] Identification of the animal (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;
    [cir] Distance and bearing of each marine mammal observed to the 
pile being driven for each sighting (if pile driving was occurring at 
time of sighting);
    [cir] Estimated number of animals (minimum/maximum/best);
    [cir] Estimated number of animals by cohort (adults, juveniles, 
neonates, group composition, etc.;
    [cir] Animal's closest point of approach and estimated time spent 
within the harassment zone; and
    [cir] Description of any marine mammal behavioral observations 
(e.g., observed behaviors such as feeding or traveling), including an 
assessment of behavioral responses to the activity (e.g., no response 
or changes in behavioral state such as ceasing feeding, changing 
direction, flushing, or breaching);
    [ssquf] Detailed information about implementation of any mitigation 
(e.g., shutdowns and delays), a description of specific actions that 
ensued, and resulting changes in behavior of the animal, if any; and
    [ssquf] All PSO datasheets and/or raw sightings data.

Reporting of Hydroacoustic Monitoring

    The Navy shall also submit a draft hydroacoustic monitoring report 
to NMFS within 60 workdays of the completion of required monitoring at 
the end of the project. The report will detail the hydroacoustic 
monitoring protocol and summarize the data recorded during monitoring. 
The final report must be prepared and submitted within 30 days 
following resolution of any NMFS comments on the draft report. If no 
comments are received from NMFS within 30 days of receipt of the draft 
report, the report shall be considered final. If comments are received, 
a final report addressing NMFS comments must be submitted within 30 
days after receipt of comments. All draft and final hydroacoustic 
monitoring reports must be submitted to 
[email protected] and [email protected]. The 
hydroacoustic monitoring report will contain the informational elements 
described in the Hydroacoustic Monitoring Plan and, at minimum, will 
include:
    [ssquf] Hydrophone equipment and methods: Recording device, 
sampling

[[Page 11887]]

rate, distance (m) from the pile where recordings were made; depth of 
water and recording device(s);
    [ssquf] 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;
    [ssquf] 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;
    [ssquf] For impact pile driving and/or DTH excavation (DTH mono-
hammer and cluster drill) (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 [micro]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);
    [ssquf] For vibratory driving/removal and/or DTH excavation (DTH 
mono-hammer and cluster drill) (per pile): Duration of driving per 
pile; mean, median, and maximum sound levels (dB re: 1 [micro]Pa): Root 
mean square sound pressure level (SPLrms), cumulative sound exposure 
level (SELcum) (and timeframe over which the sound is averaged); and
    [ssquf] One-third octave band spectrum and power spectral density 
plot.
    [ssquf] General Daily Site Conditions.
    [cir] Date and time of activities.
    [cir] Water conditions (e.g., sea state, tidal state).
    [cir] Weather conditions (e.g., percent cover, visibility).

Reporting of Injured or Dead Marine Mammals

    In the event that personnel involved in the construction activities 
discover an injured or dead marine mammal, the Navy shall report the 
incident to NMFS Office of Protected Resources (OPR) 
([email protected]), NMFS (301-427-8401) and to the 
Greater Atlantic Region New England/Mid-Atlantic Stranding Coordinator 
(866-755-6622) as soon as feasible. If the death or injury was clearly 
caused by the specified activity, the Navy must immediately cease the 
specified activities until NMFS OPR 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 this rule. The Navy 
shal not resume their activities until notified by NMFS. The report 
must include the following information:
    [ssquf] Time, date, and location (latitude/longitude) of the first 
discovery (and updated location information if known and applicable);
    [ssquf] Species identification (if known) or description of the 
animal(s) involved;
    [ssquf] Condition of the animal(s) (including carcass condition if 
the animal is dead);
    [ssquf] Observed behaviors of the animal(s), if alive;
    [ssquf] If available, photographs or video footage of the 
animal(s); and
    [ssquf] General circumstances under which the animal was 
discovered.

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 responses (e.g., intensity, duration), the context 
of any responses (e.g., critical reproductive time or location, 
migration), 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 environmental 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, this introductory discussion of our analyses 
applies to all of 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 in anticipated 
individual responses to activities, impacts of expected take on the 
population due to differences in population status, or impacts on 
habitat, they are described independently in the analysis below.
    Construction activities associated with the project, as outlined 
previously, have the potential to disturb or displace marine mammals. 
Specifically, the specified activities may result in take, in the form 
of Level A and Level B harassment from underwater sounds generated by 
pile driving activities, rotary drilling, rock hammering, and DTH. 
Potential takes could occur if marine mammals are present in zones 
ensonified above the thresholds for Level A and Level B harassment, 
identified above, while activities are underway.
    No serious injury or mortality would be expected even in the 
absence of the proposed mitigation measures. A bubble curtain shall be 
installed across any openings at the entrance of super flood basin to 
attenuate sound for the sound sources that encompass the entire ROI 
(Figure 2). During all impact driving, implementation of soft start 
procedures and monitoring of established shutdown zones will be 
required, significantly reducing the possibility of injury. Given 
sufficient notice through use of soft start (for impact driving), 
marine mammals are expected to move away from an irritating sound 
source prior to it becoming potentially injurious. In addition, PSOs 
will be stationed within the action area whenever pile driving, rotary 
drilling, rock hammering and DTH activities are underway. The Navy 
shall employ the use of three PSOs to ensure all monitoring and 
shutdown zones are properly observed. For hooded and harp seals which 
are a rare species in within the project area, we do not anticipate any 
take by Level A harassment.
    The Navy's proposed activities and associated impacts will occur 
within a limited area. Most of the work will occur behind the existing 
super flood basin walls that would act as a barrier to sound and would 
contain underwater noise to within a small portion of the Piscataqua 
River. Exposures to elevated sound levels produced during pile driving 
activities may cause behavioral disturbance of some individuals, but 
they are expected to be mild and temporary and further minimized by the 
use of a bubble curtain and soft starts. As described previously, the 
mitigation and monitoring measures are expected to further reduce the 
likelihood of injury as well as reduce behavioral disturbances.
    Effects on individuals that are taken by Level B harassment, as 
enumerated in the Estimated Take section, on the basis of reports in 
the literature as well as monitoring from other similar activities, 
will likely be limited to reactions such as increased swimming

[[Page 11888]]

speeds, increased surfacing time, or decreased foraging (if such 
activity were occurring) (e.g., Thorson and Reyff 2006). Most likely, 
individual animals will simply move away from the sound source and be 
temporarily displaced from the area, although even this reaction has 
been observed primarily only in association with impact pile driving. 
The activities analyzed here are similar to numerous other construction 
activities conducted along both Atlantic and Pacific coasts, which have 
taken place with no known long-term adverse consequences from 
behavioral harassment. These reactions and behavioral changes are 
expected to subside quickly when the exposures cease. Level B 
harassment will be minimized through use of mitigation measures 
described herein. including the soft starts and the use of the bubble 
curtain, which was not quantitatively factored into the take estimates.
    Regarding Level A harassment particularly for harbor seals and gray 
seals, monitoring and shutdown protocols, and a bubble curtain 
implemented during DTH excavation (DTH mono-hammer and cluster drill) 
and hydraulic rock hammering would minimize potential for take by Level 
A harassment. For pinnipeds, the calculated Level A harassment likely 
overestimates PTS exposure because: (1) Seals are unlikely to remain in 
the Level A harassment zone underwater long enough to accumulate 
sufficient exposure to noise resulting in PTS, and (2) the estimate 
assumes that new seals are in the Level A harassment zone every day 
during pile driving. Further as discussed above, take by Level A 
harassment would be minimized due to implementation of monitoring, 
shutdown procedures and a bubble curtain. Nonetheless, we have 
considered the potential impacts of these PTS takes occurring in this 
analysis. The degree of PTS that may incur from the Navy's activities 
are not expected to impact marine mammals such that their reproduction 
or survival could be affected. Similarly, data do not suggest that a 
single instance in which an animal accrues PTS (or TTS) and is subject 
to behavioral disturbance would result in impacts to reproduction or 
survival. If PTS were to occur, it would be at a lower level likely to 
accrue to a relatively small portion of the population by being a 
stationary activity in one particular location.
    The project is also not expected to have significant adverse 
effects on any marine mammal habitat. The project activities will not 
modify existing marine mammal habitat since the project will occur 
within the same footprint as existing marine infrastructure. Impacts to 
the immediate substrate are anticipated, but these would be limited to 
minor, temporary suspension of sediments, which could impact water 
quality and visibility for a short amount of time but which would not 
be expected to have any effects on individual marine mammals. The 
nearshore and intertidal habitat where the project will occur is an 
area of consistent vessel traffic from Navy and non-Navy vessels, and 
some local individuals would likely be somewhat habituated to the level 
of activity in the area, further reducing the likelihood of more severe 
impacts. The closest pinniped haulout used by harbor and gray seals is 
2,414 m (1.5 mi) away on the opposite side of the island and not within 
the ensonified area. There are no other biologically important areas 
for marine mammals near the project area.
    In addition, impacts to marine mammal prey species are expected to 
be minor and temporary. Overall, the area impacted by the project is 
very small compared to the available surrounding habitat. The most 
likely impact to prey will be temporary behavioral avoidance of the 
immediate area. During construction activities, it is expected that 
some fish and marine mammals would temporarily leave the area of 
disturbance, thus impacting marine mammals' foraging opportunities in a 
limited portion of the foraging range. But, because of the relatively 
small area of the habitat that may be affected, the impacts to marine 
mammal habitat are not expected to cause significant or long-term 
negative consequences.
    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 the species or stock 
through effects on annual rates of recruitment or survival:
    [ssquf] No mortality is anticipated or proposed for authorization;
    [ssquf] No Level A harassment is anticipated or proposed for 
authorization for hooded seals and harp seals;
    [ssquf] Level A harassment proposed for authorization for harbor 
and gray seals will be minimized with a bubble curtain and shutdown 
zones and is expected to be of a lower degree that would not impact the 
fitness of any animals;
    [ssquf] Anticipated incidents of Level B harassment consist of, at 
worst, temporary modifications in behavior;
    [ssquf] The required mitigation measures (i.e., bubble curtain, 
shutdown zones) are expected to be effective in reducing the effects of 
the specified activity;
    [ssquf] Minimal impacts to marine mammal habitat/prey are expected;
    [ssquf] The action area is located within an active marine shipyard 
area,
    [ssquf] There is one pinniped haulouts in the vicinity of the 
project area, but it is on the opposite side of Seavey Island and not 
within the ensonified area; and
    [ssquf] There are no known biologically important areas in the 
vicinity of the project, 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 
monitoring and mitigation measures, NMFS finds that the total marine 
mammal take from the proposed activity will 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) of the MMPA for specified 
activities other than military readiness activities. The MMPA does not 
define small numbers, 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.
    Take of five of the marine mammal stocks proposed for authorization 
will comprise at most approximately 3 percent or less of the stock 
abundance (Table 16). The number of animals proposed for authorization 
to be taken from these stocks would be considered small relative to the 
relevant stock's abundances even if each estimated take occurred to a 
new individual, which is an unlikely scenario. Based on the analysis 
contained herein of the proposed activity (including the mitigation and 
monitoring measures) and the anticipated take of marine mammals, NMFS 
preliminarily finds that small numbers of marine mammals will 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

[[Page 11889]]

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 (ESA)

    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 the Navy for the taking of marine mammals incidental to 
modification and expansion of the Portsmouth Naval Shipyard Dry Dock 1 
in Kittery, Maine, effective for one year from the date of issuance, 
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/permit/incidental-take-authorizations-under-marine-mammal-protection-act.

Request for Public Comments

    NMFS requests comment on these analyses, the proposed 
authorization, and any other aspect of this Notice of Proposed IHA for 
the proposed issuance of an IHA to the Navy for the taking of marine 
mammals incidental to modification and expansion of the Portsmouth 
Naval Shipyard Dry Dock 1 in Kittery, Maine, effective for one year 
from the date of issuance. NMFS also requests comment on the potential 
for a 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 NMFS' final decision on the request for MMPA 
authorization.
    On a case-by-case basis, NMFS may issue a one-time, 1-year IHA 
renewal with an expedited public comment period (15 days) when: (1) 
Another year of identical or nearly identical activities as described 
in the Specified Activities section is planned or (2) the activities 
would not be completed by the time the IHA expires and a second IHA 
would allow for completion of the activities beyond that described in 
the Dates and Duration section, provided all of the following 
conditions are met:
     A request for renewal is received no later than 60 days 
prior to expiration of the current IHA;
     The request for renewal must include the following:
    (1) An explanation that the activities to be conducted under the 
proposed renewal 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 
because only a subset of the initially analyzed activities remain to be 
completed under the renewal); and
    (2) A preliminary monitoring report showing the results of the 
required 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: February 25, 2022.
Kimberly Damon-Randall,
Director, Office of Protected Resources, National Marine Fisheries 
Service.
[FR Doc. 2022-04406 Filed 3-1-22; 8:45 am]
BILLING CODE 3510-22-P