[Federal Register Volume 88, Number 11 (Wednesday, January 18, 2023)]
[Proposed Rules]
[Pages 3146-3195]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2023-00332]



[[Page 3145]]

Vol. 88

Wednesday,

No. 11

January 18, 2023

Part III





Department of Commerce





-----------------------------------------------------------------------





National Oceanic and Atmospheric Administration





-----------------------------------------------------------------------





50 CFR Part 217





Taking and Importing Marine Mammals; Taking Marine Mammals Incidental 
to U.S. Navy Construction at Portsmouth Naval Shipyard, Kittery, Maine; 
Proposed Rule

  Federal Register / Vol. 88, No. 11 / Wednesday, January 18, 2023 / 
Proposed Rules  

[[Page 3146]]


-----------------------------------------------------------------------

DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

50 CFR Part 217

[Docket No. 230104-0003]
RIN 0648-BL78


Taking and Importing Marine Mammals; Taking Marine Mammals 
Incidental to U.S. Navy Construction at Portsmouth Naval Shipyard, 
Kittery, Maine

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

ACTION: Proposed rule; request for comments.

-----------------------------------------------------------------------

SUMMARY: NMFS has received a request from the U.S. Navy (Navy) for 
authorization to take marine mammals incidental to construction at the 
Portsmouth Naval Shipyard in Kittery, Maine, over the course of five 
years (2023-2028). Pursuant to the Marine Mammal Protection Act (MMPA), 
NMFS is proposing regulations to govern that take and requests comments 
on the proposed regulations. NMFS responses to comments will be 
included in the notice of the final decision.

DATES: Comments and information must be received no later than February 
17, 2023.

ADDRESSES: A copy of the Navy's application and any supporting 
documents, as well as a list of the references cited in this document, 
may be obtained online at: https://www.fisheries.noaa.gov/action/incidental-take-authorization-us-navy-construction-portsmouth-naval-shipyard-kittery-maine-0. In case of problems accessing these 
documents, please call the contact listed below.
    Submit all electronic public comments via the Federal e-Rulemaking 
Portal. Go to www.regulations.gov and enter NOAA-NMFS-2022-0133 in the 
Search box. Click on the ``Comment'' icon, complete the required 
fields, and enter or attach your comments.
    Instructions: Comments sent by any other method, to any other 
address or individual, or received after the end of the comment period, 
may not be considered by NMFS. All comments received are a part of the 
public record and will generally be posted for public viewing on 
www.regulations.gov without change. All personal identifying 
information (e.g., name, address), confidential business information, 
or otherwise sensitive information submitted voluntarily by the sender 
will be publicly accessible. NMFS will accept anonymous comments (enter 
``N/A'' in the required fields if you wish to remain anonymous). 
Attachments to electronic comments will be accepted in Microsoft Word, 
Excel, or Adobe PDF file formats only.

FOR FURTHER INFORMATION CONTACT: Reny Tyson Moore, Office of Protected 
Resources, NMFS, [email protected], (301) 427-8401.

SUPPLEMENTARY INFORMATION: 

Purpose and Need for Regulatory Action

    We received an application from the Navy requesting 5-year 
regulations and authorization to take multiple species of marine 
mammals. This proposed rule would establish a framework under the 
authority of the MMPA (16 U.S.C. 1361 et seq.) to allow for the 
authorization of take by Level A and Level B harassment of marine 
mammals incidental to the Navy's construction activities related to the 
multifunctional expansion and modification of Dry Dock 1 at the 
Portsmouth Naval Shipyard in Kittery, Maine. Please see ``Background'' 
below for definitions of harassment.

Legal Authority for the Proposed Action

    Section 101(a)(5)(A) of the MMPA (16 U.S.C. 1371(a)(5)(A)) directs 
the Secretary of Commerce to allow, upon request, the incidental, but 
not intentional, taking of small numbers of marine mammals by U.S. 
citizens who engage in a specified activity (other than commercial 
fishing) within a specified geographical region for up to 5 years if, 
after notice and public comment, the agency makes certain findings and 
issues regulations that set forth permissible methods of taking 
pursuant to that activity and other means of effecting the ``least 
practicable adverse impact'' on the affected species or stocks and 
their habitat (see the discussion below in the Proposed Mitigation 
section), as well as monitoring and reporting requirements. Section 
101(a)(5)(A) of the MMPA and the implementing regulations at 50 CFR 
part 216, subpart I provide the legal basis for issuing this proposed 
rule containing 5-year regulations, and for any subsequent Letters of 
Authorization (LOAs). As directed by this legal authority, this 
proposed rule contains mitigation, monitoring, and reporting 
requirements.

Summary of Major Provisions Within the Proposed Rule

    Following is a summary of the major provisions of this proposed 
rule regarding the Navy's construction activities. These measures 
include:
     Required monitoring of the in-water construction areas to 
detect the presence of marine mammals before beginning in-water 
construction activities;
     Shutdown of in-water construction activities under certain 
circumstances to avoid injury of marine mammals;
     Soft start for impact pile driving to allow marine mammals 
the opportunity to leave the area prior to beginning impact pile 
driving at full power; and
     Implementation of a bubble curtain during rock hammering 
and down-the-hole (DTH) cluster drilling to reduce underwater noise 
impacts.

Background

    The MMPA prohibits the ``take'' of marine mammals, with certain 
exceptions. Sections 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361 
et seq.) direct the Secretary of Commerce (as delegated to NMFS) to 
allow, upon request, the incidental, but not intentional, taking of 
small numbers of marine mammals by U.S. citizens who engage in a 
specified activity (other than commercial fishing) within a specified 
geographical region if certain findings are made and either regulations 
are proposed or, if the taking is limited to harassment, a notice of a 
proposed incidental take authorization is provided to the public for 
review.
    Authorization for incidental takings shall be granted if NMFS finds 
that the taking will have a negligible impact on the species or 
stock(s) and will not have an unmitigable adverse impact on the 
availability of the species or stock(s) for taking for subsistence uses 
(where relevant). Further, NMFS must prescribe the permissible methods 
of taking and other ``means of effecting the least practicable adverse 
impact'' on the affected species or stocks and their habitat, paying 
particular attention to rookeries, mating grounds, and areas of similar 
significance, and on the availability of the species or stocks for 
taking for certain subsistence uses (referred to in shorthand as 
``mitigation''); and requirements pertaining to the mitigation, 
monitoring and reporting of the takings are set forth. The definitions 
of all applicable MMPA statutory terms cited above are included in the 
relevant sections below.

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 the proposed action (i.e., the promulgation of 
regulations and subsequent issuance

[[Page 3147]]

of LOAs) with respect to potential impacts on the human environment.
    This action is consistent with categories of activities identified 
in Categorical Exclusion B4 (incidental take authorizations with no 
anticipated serious injury or mortality) of the Companion Manual for 
NOAA Administrative Order 216-6A, which do not individually or 
cumulatively have the potential for significant impacts on the quality 
of the human environment and for which we have not identified any 
extraordinary circumstances that would preclude this categorical 
exclusion. Accordingly, NMFS has preliminarily determined that the 
proposed action qualifies to be categorically excluded from further 
review under NEPA.
    Information in the Navy's application and this document 
collectively provide the environmental information related to the 
proposed issuance of these regulations and subsequent incidental take 
authorization for public review and comment. We will review all 
comments submitted in response to this document prior to concluding our 
review process under NEPA and making a final decision on the request 
for an incidental take authorization.

Summary of Request

    On May 9, 2022, NMFS received a request from the Navy for 
authorization to take marine mammals incidental to construction 
activities related to the multifunctional expansion and modification of 
Dry Dock 1 at Portsmouth Naval Shipyard in Kittery, Maine. We provided 
comments on the application, and the Navy submitted revised versions 
and responses to our comments on July 5, 2022, August 15, 2022, August 
19, 2022, and August 25, 2022, with the latter version deemed adequate 
and complete. On September 1, 2022, we published a notice of receipt of 
the Navy's application in the Federal Register (87 FR 53731), 
requesting comments and information related to the request. During the 
30-day comment period, we received two supportive letters from private 
citizens.
    On October 19 and 25, 2022, NMFS was notified by the Navy of 
project modifications and shifting Fleet submarine schedules that 
required the resequencing of certain activities associated with the 
construction at Dry Dock 1 in order to accommodate the modifications 
and meet the new vessel docking demands. On October 31, 2022, the Navy 
submitted an addendum to its application describing these changes. The 
requested regulations would be valid for 5 years, from April 1, 2023 
through March 31, 2028. The Navy's request is to be authorized to take 
five species by Level A and Level B harassment. Neither the Navy nor 
NMFS expect serious injury or mortality to result from this activity.
    NMFS previously issued five IHAs to the Navy for waterfront 
improvement work at the Portsmouth Naval Shipyard: in 2016 (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 in 2022 (87 FR 19886; April 6, 2022). The most 
recent IHA (87 FR 19886) provided authorization to take marine mammals 
during the first year of the construction project described in this 
notice. 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.

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 Portsmouth Naval Shipyard. 
The two additional projects, construction of a super flood basin (P-
310) and extension of portal crane rail and utilities (P-1074), are 
currently under construction. In-water work associated with these 
projects was completed under the aforementioned 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 approximate 7-year period, during which 5 years of in-
water work would occur. An IHA was issued by NMFS for the first year of 
P-381 construction activities between April 1, 2022 and March 31, 2023 
(87 FR 19866; April 6, 2022). This request is associated with the 
remaining 4 years of P-381 in-water construction activities planned to 
occur from April 1, 2023 through March 31, 2028, as well as for 
additional in-water construction activities associated with the removal 
of emergency repair components of the super flood basin that will occur 
during the proposed period of effectiveness for the proposed 
regulations. Although the in-water construction described in this 
proposed rule is anticipated to be completed by December 2026, 
unanticipated schedule delays could result in the Navy conducting 
construction activity over the full 5 years.
    The purpose of the proposed project (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 Navy's specified activity also includes emergency repairs of the P-
310 super flood basin. Construction activities will include the 
excavation and/or installation of 1,118 holes, 198 shafts, and 580 
sheet piles via impact and vibratory pile driving, hydraulic rock 
hammering, rotary drilling, and mono and cluster DTH. The construction 
activities are expected to require approximately 2,498 days if the 
activities are considered independently over the 5-year period. 
However, the actual construction duration is expected to be within four 
years as many of the construction activities will occur concurrently. 
Harbor porpoises (Phocoena phocoena), harbor seals (Phoca vitulina), 
gray seals (Halichoerus grypus), and harp seals (Pagophilus 
groenlandicus) have been observed in the proposed action area. In 
addition, hooded seals (Cystophora cristata) could occur in the 
proposed action area.

Dates and Duration

    The in-water construction activities associated with this proposed 
rule are anticipated to begin in April 2023 and proceed to December 
2026 (4 years); however, the request for incidental take authorization 
is for 5 years in the event of unexpected scheduled delays. In-water 
construction activities would occur consecutively over a 4-year period. 
The Navy plans to conduct all in-water work activities with expected 
potential for incidental harassment of marine mammals during daylight 
hours.
    Table 1 provides the estimated schedule and production rates for P-
381 construction activities. Many of the activities included in Table 1 
would span across multiple construction years and/or would occur 
concurrently. Because of mission requirements and operational schedules 
at the dry docking positions and berths, this schedule is subject to 
change. In-water construction activities for P-381 would occur 
consecutively over a 4-year period. Note, for the purposes of this 
analysis, the proposed construction years are identified as years 2 
through 5; Year 1 of the Navy's construction activities is currently 
ongoing in association with a previously issued IHA (87 FR 19886; April 
6, 2022). Vibratory pile driving

[[Page 3148]]

and extraction is assumed to occur for 141 days. Impact pile driving 
would occur for 34 days. DTH excavation (mono-hammer and cluster drill) 
would occur for 1,446 days. Rotary drilling would occur for 238 days 
(assuming that casings and sockets for cluster drills would be set, 
excavated, and removed in a single day). Rock hammering would occur for 
277 days. Note that pile driving days are not necessarily consecutive, 
and certain activities may occur at the same time, decreasing the total 
number of actual in-water construction days. The contractor could be 
working in more than one area of the berths at a time.

                                    Table 1--In-Water Construction Activities
----------------------------------------------------------------------------------------------------------------
                                    Total amount
                                   and  estimated                                                        Total
  Activity ID        Activity          dates           Activity          Method           Daily       production
                                   (construction      component                      production rate     days
                                      years *)
----------------------------------------------------------------------------------------------------------------
A1 \1\.........  Center Wall--    Drill 18 shafts  Install 102-     Rotary drill...  1 shaft/day,1        \4\ 18
                  Install          Apr 23 \3\ to    inch diameter                     hour/day.
                  Foundation       Aug 23 (2).      outer casing.
                  Support Piles.
A2 \1\.........                                    Pre-drill 102-   Rotary drill...  1 shaft/day, 9       \4\ 18
                                                    inch diameter                     hours/day.
                                                    socket.
A3 \1\.........                                    Remove 102-inch  Rotary drill...  1 casing/day,15      \4\ 18
                                                    outer casing.                     minutes/casing.
A4 \1\.........                                    Drill 78-inch    Cluster drill    6.5 days/shaft,     \4\ 117
                                                    diameter shaft.  DTH.             10 hours/day.
R \1\..........  Dry Dock 1       Install 48       28-inch wide Z-  Impact with      8 sheets/day, 5       \4\ 6
                  North            sheet piles      shaped sheets.   initial          minutes and
                  Entrance--Inst   Apr 23 \3\ to                     vibratory set.   300 blows/pile.
                  all Temporary    May 23 (2).
                  Cofferdam.
1..............  Berth 11--       Remove 112       Concrete         Hydraulic rock   5 hours/day....      \4\ 56
                  Remove Shutter   panels Apr 23    shutter panels.  hammering.
                  Panels.          \3\ to May 23
                                   (2).
2..............  Berth 1--        Remove 168       25-inch-wide Z-  Vibratory        4 piles/day....      \4\ 42
                  Remove Sheet     sheet piles      shaped.          extraction.
                  Piles.           Apr 23 \3\ to
                                   Jun 24 (2, 3).
3..............  Berth 1--Remove  2,800 cubic      Removal of       Hydraulic rock   2.5 hours/day..      \4\ 47
                  Granite Block    yards (cy) Apr   granite blocks.  hammering.
                  Quay Wall.       23 \3\ to Jun
                                   24 (2, 3).
4..............  Berth 1--Top of  320 linear feet  Mechanical       Hydraulic rock   10 hours/day...      \4\ 74
                  Wall Removal     (lf) Apr 23      concrete         hammering.
                  for Waler        \3\ to Jun 24    removal.
                  Installation.    (2, 3).
5..............  Berth 1--        Install 28       28-inch-wide Z-  Impact with      4 piles/day, 5        \4\ 8
                  Install          sheet piles      shaped.          initial          minutes/pile
                  southeast        Apr 23 to Jul                     vibratory set.   and 300 blows/
                  corner Support   23 (2).                                            pile.
                  of Excavation
                  (SOE).
6..............  Berth 11--       700 cy Apr 23    Excavate         Hydraulic rock   12 hours/day...     \34\ 60
                  Mechanical       \3\ to Aug 23    Bedrock.         hammering.
                  Rock Removal     (2).
                  at Basin Floor.
7..............  Berth 11 Face--  Drill 924        4-6 inch         DTH mono-hammer  27 holes/day,        \4\ 35
                  Mechanical       relief holes     diameter holes.                   22 min/hole.
                  Rock Removal     Apr 23 \3\ to
                  at Basin Floor.  Aug 23 (2).
8..............  Install          Install 14       28-inch-wide Z-  Impact with      4 piles/day, 5            4
                  Temporary        sheet piles      shaped.          initial          minutes/pile
                  Cofferdam        Apr 23 to Jun                     vibratory set.   and 300 blows/
                  Extension.       23 (2).                                            pile.
9a.............  Gantry Crane     Drill 16 shafts  Set 102-inch     Rotary drill...  1 shaft/day, 1           16
                  Support Piles    Apr 23 to Aug    diameter                          hours/day.
                  at Berth 1       23 (2).          casing.
                  West.
9b.............                                    Pre-drill 102-   Rotary drill...  1 shaft/day, 9           16
                                                    inch rock                         hours/day.
                                                    socket.
9c.............                                    Remove 102-      Rotary drill...  1 casing/day             16
                                                    inch casing.                      15, minutes/
                                                                                      casing.
9d.............                                    72-inch          Cluster drill    5 days/shaft,            80
                                                    diameter         DTH.             10 hours/day.
                                                    shafts.
10 \2\.........  Berth 1--        300 cy Apr 23    Excavate         Hydraulic rock   13 cy/day 12         \5\ 25
                  Mechanical       \3\ to Sep 23    Bedrock.         hammering.       hours/day.
                  Rock Removal     (2).
                  at Basin Floor.
11.............  Dry Dock 1       Drill 50 rock    9-inch diameter  DTH mono-hammer  2 holes/day, 5       \4\ 25
                  North            anchors Apr 23   holes.                            hours/hole.
                  Entrance--Dril   \3\ to Oct 23
                  l Tremie Tie     (2).
                  Downs.
12.............  Center Wall--    Install 15       28-inch wide Z-  Impact with      4 piles/day 5             4
                  Install Tie-In   sheet piles      shaped.          initial          minutes/pile
                  to Existing      Apr 23 to Dec                     vibratory set.   and 300 blows/
                  West Closure     23 (2).                                            pile.
                  Wall.
13a............  Dry Dock 1       Drill 20 shafts  Set 102-inch     Rotary drill...  1 shaft/day, 1           20
                  North--Tempora   May 23 to Nov    diameter                          hours/day.
                  ry Work          24 (2, 3).       casing.
                  Trestle Piles.
13b............                                    Pre-drill 102-   Rotary drill...  1 shaft/day, 9           20
                                                    inch rock                         hours/day.
                                                    socket.
13c............                                    Remove 102-      Rotary drill...  1 casing/day,            20
                                                    inch casing.                      15 minutes/
                                                                                      casing.
13d............                                    84-inch          Cluster drill    3.5 days/shaft,          70
                                                    diameter         DTH.             10 hours/day.
                                                    shafts.
14.............  Dry Dock 1       Remove 20 piles  84-inch          Rotary drill...  1 day/pile, 15           20
                  North--Remove    May 23 to Nov    diameter drill                    minutes/pile.
                  Temporary Work   24 (2, 3).       piles.
                  Trestle Piles.
15a............  Dry Dock 1       Drill 18 shafts  Set 84-inch      Rotary drill...  1 shaft/day, 1           18
                  North--Install   May 23 to Nov    casing.                           hours/day.
                  Leveling Piles   24 (2, 3).
                  (Diving Board
                  Shafts).
15b............                                    Pre-drill 84-    Rotary drill...  1 shaft/day, 9           18
                                                    inch rock                         hours/day.
                                                    socket.
15c............                                    Remove 84-inch   Rotary drill...  1 casing/day,            18
                                                    casing.                           15 minutes/
                                                                                      casing.

[[Page 3149]]

 
15d............                                    78-inch          Cluster drill    7.5 days/shaft,         135
                                                    diameter shaft.  DTH.             10 hours/day.
16a............  Wall Support     Drill 20 shafts  Set 102-inch     Rotary drill...  1 shaft/day, 1           20
                  Shafts for Dry   Jun 23 to Nov    diameter                          hours/day.
                  Dock 1 North     24 (2, 3).       casing.
                  (Berth 11 Face
                  and Head Wall).
16b............                                    Pre-drill 102-   Rotary drill...  1 shaft/day, 9           20
                                                    inch rock                         hours/day.
                                                    socket.
16c............                                    Remove 102-inch  Rotary drill...  1 casing/day,            20
                                                    casing.                           15 minutes/
                                                                                      casing.
16d............                                    Drill 78-inch    Cluster drill    7.5 days/shaft,         150
                                                    diameter shaft.  DTH.             10 hours/day.
17a............  Foundation       Drill 23 shafts  Set 126-inch     Rotary drill...  1 shaft/day, 1           23
                  (Floor) Shafts   Jun 23 to Nov    diameter                          hours/day.
                  for Dry Dock 1   24 (Const.       Casing.
                  North            years 2, 3).
                  (Foundation
                  Support Piles).
17b............                                    Pre-drill 126-   Rotary drill...  1 shaft/day, 9           23
                                                    inch rock                         hours/day.
                                                    socket.
17c............                                    Remove 126-inch  Rotary drill...  1 casing/day,            23
                                                    casing.                           60 minutes/
                                                                                      casing.
17d............                                    Drill 108-inch   Cluster drill    8.5 days/shaft,         196
                                                    diameter         DTH.             10 hours/day.
                                                    shafts.
18.............  Berth 11 End     Remove 60 sheet  28-inch wide Z-  Vibratory        8 piles/day, 5       \5\ 10
                  Wall--Remove     piles Jul 23     shaped.          extraction.      minutes/pile.
                  Temporary        to Aug 23 (2,
                  Guide Wall.      3).
19.............  Remove Berth 1   Remove 28 sheet  28-inch-wide Z-  Vibratory        8 piles/day, 5        \4\ 5
                  southeast        piles Jul 23     shaped.          extraction.      minutes/pile.
                  corner SOE.      to Sep 23 (2).
20 \2\.........  Removal of       Remove 108       28-inch-wide Z-  Vibratory        6 piles/day, 5           18
                  Berth 1          sheet piles      shaped.          extraction.      minutes/pile.
                  Emergency        Apr 23 \3\ to
                  Repair Sheet     Jul 23 (2).
                  Piles.
21 \2\.........  Removal of       500 cy Apr 23    Mechanical       Hydraulic rock   4 hours/day....          15
                  Berth 1          \3\ to Aug 23    concrete         hammering.
                  Emergency        (2).             removal.
                  Repair Tremie
                  Concrete.
22.............  Center Wall      Install 72 rock  9-inch diameter  DTH mono-        2 holes/day, 5           36
                  Foundation--Dr   anchors Aug 23   holes.           hammer.          hours/hole.
                  ill in           to May 24 (2,
                  Monolith Tie     3).
                  Downs.
23.............  Center Wall--    Remove 16 sheet  28-inch-wide Z-  Vibratory        8 piles/day, 5        \5\ 3
                  Remove Tie-In    piles \6\ Aug    shaped.          extraction.      minutes/pile.
                  to Existing      23 to Aug 24
                  West Closure     (2, 3).
                  Wall (Dry Dock
                  1 North) \4\.
24.............  Center Wall      Install 23       28-inch wide Z-  Impact with      2 piles/day, 5           12
                  East--Sheet      sheet piles      shaped.          initial          minutes/pile
                  Pile Tie-In to   Aug 23 to Oct                     vibratory set.   and 300 blows/
                  Existing Wall.   24 (2, 3).                                         pile.
25.............  Remove Tie-In    Remove 15 sheet  28-inch wide Z-  Vibratory        8 piles/day, 5        \5\ 3
                  to West          pile Dec 23 to   shaped.          extraction.      minutes/pile.
                  Closure Wall     Dec 24 (2, 3).
                  (Dry Dock 1
                  West).
26.............  Remove Center    Remove 23 sheet  28-inch wide Z-  Vibratory        8 piles/day, 5       \5\ 12
                  Wall East--      piles Dec 23     shaped.          extraction.      minutes/pile.
                  Sheet Pile Tie-  to Dec 24 (2,
                  In to Existing   3).
                  Wall (Dry Dock
                  1 West).
27.............  Dry Dock 1       Remove 96 sheet  28-inch wide Z-  Vibratory        8 piles/day, 5           12
                  North            piles Jan 24     shaped.          extraction.      minutes/pile.
                  Entrance--Remo   to Sep 24
                  ve Temporary     (Const. years
                  Cofferdam.       2, 3).
28.............  Remove           Remove 14 sheet  28-inch wide Z-  Vibratory        8 piles/day, 5            2
                  Temporary        piles Jan 24     shaped.          extraction.      minutes/pile.
                  Cofferdam        to Sep 24 (2,
                  Extension.       3).
29a............  Dry Dock 1       Drill 20 shafts  Set 102-inch     Rotary drill...  1 shaft/day, 1           20
                  West--Install    Apr 24 to Feb    diameter                          hours/day.
                  Temporary Work   26 (3, 4).       casing.
                  Trestle Piles.
29b............                                    Pre-drill 102-   Rotary drill...  1 shaft/day, 9           20
                                                    inch rock                         hours/day.
                                                    socket.
29c............                                    Remove 102-inch  Rotary drill...  1 casing/day,            20
                                                    casing.                           15 minutes/
                                                                                      casing.
29d............                                    84-inch          Cluster drill    3.5 days/shaft,          70
                                                    diameter         DTH.             10 hours/day.
                                                    shafts.
30.............  Dry Dock 1       Remove 20 piles  84-inch          Rotary drill...  1 day/pile, 15           20
                  West--Remove     Apr 24 to Feb    diameter piles.                   minutes/pile.
                  Temporary Work   26 (3, 4).
                  Trestle Piles.
31a............  Wall Support     Drill 22 shafts  Set 102-inch     Rotary drill...  1 shaft/day, 1           22
                  Shafts for Dry   Jun 24 to Feb    diameter                          hours/day.
                  Dock 1 West      26 (3, 4).       casing.
                  (Berth 1 Face).
31b............                                    Pre-drill 102-   Rotary drill...  1 shaft/day, 9           22
                                                    inch rock                         hours/day.
                                                    socket.
31c............                                    Remove 102-inch  Rotary drill...  1 casing/day,            22
                                                    casing.                           15 minutes/
                                                                                      casing.
31d............                                    78-inch          Cluster drill    7.5 days/shaft,         165
                                                    diameter shaft.  DTH.             10 hours/day.

[[Page 3150]]

 
32a............  Foundation       Drill 23 shafts  Set 126-inch     Rotary drill...  1 shaft/day, 1           23
                  (Floor) Shafts   Jun 24 to Feb    casing.                           hours/day.
                  for Dry Dock 1   26 (3, 4).
                  West
                  (Foundation
                  Support Piles).
32b............                                    Pre-drill 126-   Rotary drill...  1 shaft/day, 9           23
                                                    inch rock                         hours/day.
                                                    socket.
32c............                                    Remove 126-      Rotary drill...  1 casing/day,            23
                                                    inch casing.                      15 minutes/
                                                                                      casing.
32d............                                    Drill 108-inch   Cluster drill    8.5 days/shaft,         196
                                                    diameter shaft.  DTH.             10 hours/day.
33a............  Dry Dock 1       Drill 18 shafts  Set 84-inch      Rotary Drill...  1 shaft/day, 1           18
                  West--Install    Jun 24 to Feb    casing.                           hours/day.
                  Leveling Piles   26 (3, 4).
                  (Diving Board
                  Shafts).
33b............                                    Pre-drill 84-    Rotary drill...  1 shaft/day, 9           18
                                                    inch rock                         hours/day.
                                                    socket.
33c............                                    Remove 84-inch   Rotary drill...  1 casing/day,            18
                                                    casing.                           15 minutes/
                                                                                      casing.
33d............                                    Drill 78-inch    Cluster drill    7.5 days/shaft,         135
                                                    diameter shaft.  DTH.             10 hours/day.
34.............  Dry Dock 1       Install 36 rock  9-inch diameter  DTH mono-hammer  2 holes/day, 5           18
                  North--Tie       anchors Jul 24   holes.                            hours/hole.
                  Downs.           to Jul 25 (3,
                                   4).
35.............  Dry Dock 1       Install 36 rock  9-inch diameter  DTH mono-hammer  2 holes/day, 5           18
                  West--Install    anchors Dec 25   hole.                             hours/hole.
                  Tie Downs.       to Dec 26 (4,
                                   5).
----------------------------------------------------------------------------------------------------------------
Total excavated holes/drilled     1,118/198/580..  ...............  ...............  ...............       2,498
 shafts/sheet piles.
----------------------------------------------------------------------------------------------------------------
* Note, for the purposes of this analysis, the proposed construction years are identified as years 2 through 5;
  potential marine mammal takes incidental to Year 1 of the Navy's construction activities were authorized under
  a previously issued IHA (87 FR 19886; April 6, 2022).
\1\ These activities were not included in the original application made available for public review during the
  Notice of Receipt comment period (NOR; 87 FR 53731), but have been added due to changes needed in the proposed
  construction schedule.
\2\ These activities were included in the original application, but the amount of activity proposed has been
  modified due to changes needed in the proposed construction schedule.
\3\ These activities began in construction year 1.
\4\ These activities began in year 1. Only the number of production days occurring in construction years 2
  through 6 are presented.
\5\ Additional production days are included to account for equipment repositioning.
\6\ Sheet piles were installed in construction year 1.

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 (Figure 1). 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, 1640 feet 
(ft) from its southwest bank, 200 m (656 ft) from its north bank, and 
approximately 4 kilometers (km) (2.5 mi) from the mouth of the river.
    Water depths in the proposed project area range from 6.4 m (21 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 4.6 m (15 
ft) in the shallowest areas to 21 m (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.
    The nearshore environment of the Shipyard is characterized by a mix 
of hard bottom, gravel, soft sediments, rock outcrops, and rocky 
shoreline associated with fast tidal currents near the installation. 
The nearshore areas surrounding Seavey Island are predominately hard 
bottom (65 percent of benthic habitat) and gravel (26 percent) habitat, 
with only 9 percent soft bottom sediments within the surveyed area 
around Seavey Island (Tetra Tech, 2016). 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. 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'' (Federal Geographic Data 
Committee, 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., 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 (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 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

[[Page 3151]]

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
[GRAPHIC] [TIFF OMITTED] TP18JA23.000


[[Page 3152]]


[GRAPHIC] [TIFF OMITTED] TP18JA23.001

BILLING CODE 3510-22-C

[[Page 3153]]

Detailed Description of the Specified Activity

    The Navy's proposed P-381 project would 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. 
Several steps are required to convert the super flood basin to a dry 
dock with two positions fully capable of supporting the maintenance of 
submarines while maintaining access to the existing interior dry dock 
(Dry Dock 1 East). The dry dock positions (including the center wall) 
will be constructed using large precast segments (referred to as 
monoliths) that require both sidewall and base support. The monoliths 
will be manufactured offsite and transported to the construction site. 
Segments will be floated and/or lifted into place to create the center 
wall, followed by Dry Dock 1 North, and finally Dry Dock 1 West. Once 
the monoliths are set and grouted in place, the respective dry docks 
can be dewatered allowing the remaining interior construction to be 
performed in dry conditions.
    P-381 years 2 through 5 (i.e., the time period of the Navy's 
specified activity for this proposed rule) construction activities will 
complete bedrock removal and 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. Most of the in-water 
construction 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. However, the west 
closure wall will be removed in order to install the Dry Dock 1 North 
entrance structure and caisson. In addition, the caissons may not 
always be in place throughout in-water construction. As such, the 
analyses presented herein conservatively assume the west closure wall, 
as well as the future caissons, would not be present throughout in-
water construction activities.
    The Navy's request also considers emergency repairs of the P-310 
super flood basin. During P-310 super flood testing in January 2022, 
excessive exfiltration (i.e., transport of material outside of the 
basin) was observed along Berths 1 and 2 and between the west closure 
wall and super flood basin entrance structure. Emergency structural 
repairs were required to reduce excessive transport of material through 
the berths and west closure wall/entrance structure and prevent further 
damage. As a result, 216 28-inch Z-shaped sheet piles were installed 
along the Berth 1 face. After installation, these sheet piles were cut 
off approximately 10 ft above the mudline and concrete was tremie 
placed behind them to plug any gaps in the existing structure that 
contributed to the exfiltration. The removal of these 216 Berth 1 
emergency repair piles and excess tremie concrete (approximately 382 
cubic meters, 500 cubic yards (cy)) will be completed during this LOA 
period and are accounted for in the Navy's request. Similarly, 10 28-
inch wide, Z-shaped sheet piles were installed between the super flood 
basin entrance structure and the west closure wall, cut off 
approximately 3 m (10 ft) above the mudline, and had concrete tremie 
placed behind them. These 10 sheet piles will be removed during the P-
381 year 1 IHA period (covered under the IHA issued by NMFS for the 
first year of P-381 construction activities; 87 FR 19866; April 6, 
2022).
    Several additional preparatory activities (e.g., torch cutting, 
dredging, etc) will not create noise expected to result in harassment 
of marine mammals. Noise created during dredging of sediment and 
demolition debris (e.g., bedrock, granite blocks, concrete) is unlikely 
to exceed that generated by other normal shipyard activities and is not 
expected to result in incidental take of marine mammals. Activities 
such as grouting (i.e., pouring of concrete) and torch cutting are not 
noisy by design and would not result in incidental take of marine 
mammals. These activities are not addressed in the analyses of noise 
producing actions in the Navy's request, and are not considered by NMFS 
in our analysis, but are included in the work descriptions to clarify 
the construction progression.

P-381 In-Water Construction Activities

    The proposed work remaining for P-381 can be generally grouped into 
five categories for ease of explanation: temporary structures, 
mechanical bedrock removal, continued demolition of super flood basin 
wall components, center wall tie-downs, and dry dock foundation and 
gantry crane support. Each category involves one or more activities 
expected to generate noise that could result in injury or harassment of 
marine mammals. Some of these activities are a continuation of work 
started in year 1, which were covered under a separate IHA issued by 
NMFS on April 6, 2022 (87 FR 19886).
    Temporary Structures--Several temporary structures would be 
installed and removed to facilitate the construction of the dry docks. 
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 
west closure wall structure will be surrounded by a temporary 
cofferdam. The cofferdam will be constructed with 48 28-inch wide, Z-
shaped sheet piles. The sheet piles will be installed using an initial 
vibratory set followed by driving with impact hammers to refusal.
    The temporary guide wall along the Berth 11 end wall installed 
during year 1 (60 28-inch wide, Z-shaped sheet piles) would be removed 
with a vibratory hammer. An extension to the temporary cofferdam around 
the Dry Dock 1 entrance structure installed during P-381 year 1 would 
also be constructed. The extension would consist of 14 28-inch wide, Z-
shaped sheet piles. The extension and the cofferdam (96 28-inch wide, 
Z-shaped sheet piles) would be removed in 2024 using a vibratory 
hammer.
    A temporary work trestle would be constructed to support the 
excavation of large shafts within the individual dry docking positions. 
The trestle would be installed in Dry Dock 1 North first and then 
relocated to Dry Dock 1 West. The trestle system would be supported by 
4 84-inch steel pipe piles and would be relocated five times within 
each dry dock. As a result, the piles would be installed and removed 20 
times in Dry Dock 1 North and 20 times in Dry Dock 1 West. The piles 
would be installed with a cluster drill consisting of multiple DTH 
hammers and removed with a rotary drill. Before the cluster drill would 
be deployed, a 102-inch casing would be set into bedrock and a 5-ft 
(1.5-m) deep rock socket would be excavated with a rotary drill (see 
Figure 1-4 in the Navy's application). The socket would be filled with 
concrete and a second, 84-inch casing would be installed inside the 
larger casing and set in the concrete. No drilling would be required to 
install the second casing. The outer casing would then be removed with 
a rotary drill. The 84-inch diameter cluster drill would operate 
independently inside the second casing to excavate the shaft. Once the 
shaft is drilled the inner casing would be removed by torch cutting.
    A temporary tie-in consisting of 15 28-inch wide, Z-shaped sheet 
piles would be installed between the center wall foundation and the 
west closure wall at Dry Dock 1 West. Twenty-three 28-inch wide, Z-
shaped sheet piles would also be installed on the easterly end of Dry 
Dock 1 west to provide a

[[Page 3154]]

similar temporary tie-in to the center wall foundation near the 
entrance to Dry Dock 1 east. The sheet piles would be installed using 
an initial vibratory set followed by driving with impact hammers. These 
tie-ins would be removed using a vibratory hammer along with the Dry 
Dock 1 North tie-in to the west closure wall (16 28-inch wide, Z-shaped 
sheet piles) that was installed under the P-381 year 1 IHA (87 FR 
19886).
    To support excavation activities along Berth 1, 28 28-inch wide, Z-
shaped sheet piles would be installed at the southeast corner of the 
berth using a combination of vibratory and impact hammers. These piles 
would be removed using a vibratory hammer.
    Mechanical Bedrock Removal--Mechanical removal of bedrock would be 
completed by the end of 2023 using various methods appropriate for the 
removal location and as needed to avoid damage to adjacent structures. 
Bedrock removal would occur along the Berth 11 face and abutment and 
along Berth 1.
    Bedrock would be removed by breaking it up with a hydraulic hammer 
(i.e., hoe ram or breaker). To protect adjacent structures during 
mechanical bedrock removal, 924 4-6-inch diameter relief holes would be 
drilled using a DTH mono-hammer. A total of approximately 918 cubic 
meters (1,200 cy) of bedrock are anticipated to be removed.
    Demolition of Super Flood Basin Wall Components--Demolition of 
existing wall components would include the removal of shutter panels, 
granite quay walls, sheet piles, and concrete making up the super flood 
basin. Demolition of existing wall structures would be conducted using 
a rock hammer. Specifically, the remaining sections of the existing 
concrete shutter panels making up the face of Berth 11 (112 panels), 
portions of the granite block quay wall (2,141 cm, 2,800 cy) at Berth 
1, and the remaining existing sheet pile wall at Berth 1 (168 25-inch 
wide, Z-shaped sheet piles) would be removed.
    The installation of a structural support waler (steel beam) at 
Berth 1 would also be completed. To complete the installation of the 
waler, about 98 m (320 linear ft) of concrete wall would be demolished 
using a hydraulic rock hammer.
    Center Wall Tie-downs--Additional work in the center wall area 
would involve the installation of support tie downs for future tremie 
concrete work. The tie downs require the placement of a total of 194 
rock anchors requiring 9-inch diameter holes. The rock anchors would be 
installed using a DTH mono-hammer.
    Dry Dock and Gantry Crane Support--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 excavating 18 78-inch 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 excavated using a cluster drill consisting of 
multiple DTH mono-hammers. Before the cluster drill is deployed, a 102-
inch diameter casing would be set into bedrock and a 5 foot deep rock 
socket would be excavated using a 102-inch diameter rotary drill (see 
Figure 1-4 of the Navy's application). The rock socket would be filled 
with concrete and a second, 78-inch diameter casing would be installed 
inside the 102-inch casing and set in the concrete. No drilling is 
required to install the second casing. The 102-inch diameter outer 
casing would then be removed with a rotary drill.
    The future Dry Dock 1 North and Dry Dock 1 West require significant 
structural reinforcement to provide an adequate foundation for the 
installation of the large pre-cast monolith structures forming the dry 
dock interior. Reinforcement of the individual dry dock foundations and 
walls would begin first at Dry Dock 1 North and, once completed, 
continue at Dry Dock 1 West. Twenty 78-inch diameter shafts would be 
excavated along the Berth 11 face and head wall to support the walls of 
Dry Dock 1 North. Along the floor of Dry Dock 1 North, 23 108-inch 
diameter shafts would be excavated for the installation of the 
foundation support piles and 18 78-inch diameter shafts would be 
excavated for the installation of leveling piles (i.e., diving board 
shafts).
    The dry dock foundation and wall support pile and leveling pile 
shafts would be filled with concrete to create the support piles for 
the dry dock walls and floors. The shafts would be excavated using a 
cluster drill consisting of multiple DTH hammers in the same manner as 
previously described for the temporary work trestle piles. Once the 
wall and foundation support piles and leveling piles for Dry Dock 1 
North have been installed, foundation and wall support piles and 
leveling piles would be installed for Dry Dock 1 West. Twenty-two 78-
inch diameter shafts would be excavated along the Berth 1 face to 
support the walls of Dry Dock 1 West. Twenty-three 108-inch diameter 
shafts would be excavated along the floor of Dry Dock 1 West for the 
installation of foundation support piles and 18 78-inch shafts would be 
excavated for the installation of leveling piles (i.e., diving board 
shafts). The casing sizes and rotary drill sizes proposed for each 
shaft are specified in Table 1.
    The large concrete monolithic sections used to create the dry docks 
and the center wall separation would be placed using a gantry crane. 
The gantry crane system would be structurally supported by the 
installation of 16 72-inch diameter shafts installed along the western 
extent of the Berth 1 face. The shafts would be installed using a DTH 
cluster drill as described for the temporary work trestle piles. The 
casing sizes and rotary drill sizes proposed for the gantry crane 
support shafts are specified in Table 1.

P-310 Emergency Repairs

    Testing of the super flood basin on January 5, 2022 resulted in 
excess exfiltration through Berths 1 and 2, prompting the need for 
emergency repairs along Berth 1 as well as between the super flood 
basin entrance structure and the west closure wall. Emergency repairs 
consisted of the installation of sheet piles and the tremie pouring of 
concrete to fill in gaps along the structure walls and floor. 
Installation of emergency repairs at Berth 1 and the installation and 
removal of emergency repairs at the west closure wall and entrance 
structure occurred before the period described in the Navy's LOA 
application. Only the removal of Berth 1 emergency repair components 
would occur during the requested LOA period.
    The removal of the 216 28-inch wide, Z-shaped sheet piles along the 
Berth 1 face would be completed through direct pulling via barge-
mounted crane or by vibratory hammer. Specific methods will be 
determined by the contractor based on resistance to extraction from the 
seabed. Direct pulling via crane is not anticipated to generate harmful 
levels of underwater sound. If required, the use of the vibratory 
hammer to extract the installed sheet piles would be limited to an 
initial effort to break the sheets loose, allowing them to be directly 
pulled out. As a conservative measure, vibratory extraction of these 
sheet piles is assumed for all analyses.
    The removal of 765 cubic meters (1,000 cy) of tremie concrete is 
anticipated to require use of a hydraulic rock hammer to break up 
material into smaller pieces. Smaller pieces would

[[Page 3155]]

then be retrieved via excavator bucket for offsite disposal. The Navy 
estimates daily active use of the rock hammer for the removal of 
concrete from emergency repairs to be 4 hours per day.

Means and Methods for Noise Producing Activities

    Only 28-inch wide, Z-shaped sheet piles would be installed or 
removed with pile-driving equipment during P-381 construction. The 
installation of 28-inch wide, Z-shaped steel sheet 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. Pile removal activities would 
use cranes and vibratory hammers exclusively.
    The removal of bedrock and concrete and the demolition of concrete 
shutter panels at Berth 11 and granite blocks and sheet piles at Berth 
1 during P-381 construction would be by mechanical means. These 
features would be demolished using a hydraulic rock hammer (i.e., hoe 
ram). The type/size of rock hammers used would be determined by the 
contractor selected to perform the work.
    Two methods of rock excavation would be used during P-381 
construction; DTH excavation and rotary drilling. During P-381 
construction, rotary drilling would be used to set the casings and pre-
drill rock sockets for DTH cluster drills. DTH excavation using mono-
hammers would be used to create shafts for rock anchors and tie downs 
and for the excavation of relief holes during mechanical bedrock 
removal. For the largest shafts (greater than 42-inches 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 (see Figure 1-5 in the Navy's application).

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. No 
ancillary activities are anticipated during the construction period 
that would require unimpeded access to the super flood basin. 
Therefore, it is anticipated that there would be space available within 
the project area for additional construction equipment. A maximum of 13 
pieces of equipment could potentially operate in the project area at a 
single time. While this is an unlikely scenario, it could occur for a 
very brief period. Construction equipment would be staged along the 
perimeter of the super flood basin (Berth 11, Berth 1 and head wall) as 
well on multiple barges within the super flood basin. Table 2 provides 
a summary of possible equipment combinations that could be used 
simultaneously over the course of the proposed construction period.

                                Table 2--Summary of Multiple Equipment Scenarios
----------------------------------------------------------------------------------------------------------------
                  Year                      Quantity                            Equipment
----------------------------------------------------------------------------------------------------------------
2023...................................               5  Rock Hammer (2), Vibratory Hammer (2), Impact Hammer
                                                          (1).
                                                      5  Rock Hammer (2), Vibratory Hammer (1), Impact Hammer
                                                          (1), DTH Mono-hammer (1).
                                                      5  Rock Hammer (1), Vibratory Hammer (1), Impact Hammer
                                                          (1), DTH Mono-hammer (1), Rotary Drill (1).
                                                      5  Rock Hammer (1), Vibratory Hammer (1), DTH Mono-hammer
                                                          (1), Cluster Drill (2).
                                                      5  Cluster Drill (2), Vibratory Hammer (1), Mono-hammer
                                                          DTH (1), Rotary Drill (1).
                                                      5  Rock Hammer (1), Impact Hammer (1), DTH Mono-hammer
                                                          (1), Cluster Drill (2).
                                                      6  Rock Hammer (2), DTH Mono-hammer (2), Cluster Drill
                                                          (1), Rotary Drill (1).
                                                      6  Rock Hammer (2), Vibratory Hammer (1), DTH Mono-hammer
                                                          (1), Rotary Drill (2).
                                                      8  Rock Hammer (2), Vibratory Hammer (2), DTH Mono-hammer
                                                          (2), Cluster Drill (2).
                                                     10  Rock Hammer (3), Vibratory Hammer (2), Impact hammer
                                                          (1), DTH Mono-hammer (2), Cluster Drill (2).
                                                     13  Rock Hammer (5), Cluster Drill (2), Vibratory Hammer
                                                          (2), Impact Hammer (1), Mono-hammer DTH (3).
2024...................................               8  Rock Hammer (2), Vibratory Hammer (2), DTH Mono-hammer
                                                          (2), Cluster Drill (2).
                                                      5  Cluster Drill (2), DTH mono-hammer (1), Vibratory
                                                          hammer (1), Impact Hammer (1).
                                                      3  Cluster Drill (2), DTH mono-hammer (1).
                                                      3  Cluster Drill (1), Rotary Drill (1), DTH mono-hammer
                                                          (1).
                                                      3  Rotary Drill (2), DTH mono-hammer (1).
2025...................................               3  Cluster Drill (2), DTH mono-hammer (1).
                                                      3  Cluster Drill (1), Rotary Drill (1), DTH mono-hammer
                                                          (1).
                                                      3  Rotary Drill (2), DTH mono-hammer (1).
                                                      2  Rotary Drill (2).
                                                      2  Cluster Drill (2).
----------------------------------------------------------------------------------------------------------------
Source: 381 Constructors, 2022.

    Proposed mitigation, monitoring, and reporting measures are 
described in detail later in this document (please see Proposed 
Mitigation and Proposed Monitoring and Reporting).

Description of Marine Mammals in the Area of Specified Activities

    Sections 3 and 4 of the application summarize available information 
regarding status and trends, distribution and habitat preferences, and 
behavior and life history of the potentially affected species. NMFS 
fully considered all of this information, and we refer the reader to 
these descriptions, incorporated in this preamble by reference, instead 
of reprinting the information. Additional information regarding 
population trends and threats may be found in NMFS' Stock Assessment 
Reports (SARs; www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments) and more general 
information about these species (e.g., physical and behavioral 
descriptions) may be found on NMFS' website (https://www.fisheries.noaa.gov/find-species).
    Table 3 lists all species or stocks for which take is expected and 
proposed to be authorized for this activity, and summarizes information 
related to the population or stock, including regulatory status under 
the MMPA and Endangered Species Act (ESA) and potential biological 
removal (PBR), where known. PBR is defined by the MMPA as the maximum 
number of animals, not including natural mortalities, that may be 
removed from a marine mammal stock while allowing that stock to reach 
or maintain its optimum sustainable population (as

[[Page 3156]]

described in NMFS' SARs). While no serious injury or mortality is 
expected to occur, PBR and annual serious injury and mortality from 
anthropogenic sources are included here as gross indicators of the 
status of the species or stocks 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 stocks managed under the MMPA in this region 
are assessed in NMFS' U.S. Atlantic and Gulf of Mexico SARs. All values 
presented in Table 3 are the most recent available at the time of 
publication (including from the 2021 SARs) and are available online at: 
www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments).

                                              Table 3--Species Likely Impacted by the Specified Activities
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                               Stock  abundance
                                                                                         ESA/MMPA status;     Nbest,  (CV, Nmin,               Annual M/
             Common name                  Scientific name             MMPA stock          strategic (Y/N)   most recent  abundance     PBR       SI \3\
                                                                                                \1\               survey) \2\
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                 Order Cetartiodactyla--Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Phocoenidae (porpoises):
    Harbor Porpoise.................  Phocoena phocoena......  Gulf of Maine/Bay of     -; N                95,543 (0.31; 74,034;         851        164
                                                                Fundy.                                       2016).
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                         Order Carnivora--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-assessments assessments. CV is coefficient of variation; Nmin is the minimum estimate of stock abundance. In some cases, CV is not applicable (N.A.).
\3\ These values, found in NMFS's SARs, represent annual levels of human-caused mortality plus serious injury from all sources combined (e.g.,
  commercial fisheries, ship strike). Annual M/SI often cannot be determined precisely and is in some cases presented as a minimum value or range. A CV
  associated with estimated mortality due to commercial fisheries is presented in some cases.
\4\ 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.

    As indicated above, all five species (with five managed stocks) in 
Table 3 temporally and spatially co-occur with the activity to the 
degree that take is reasonably likely to occur.

Harbor Porpoise

    Harbor porpoises occur from the coastline to deep waters (>1,800 m, 
5906 ft); Westgate et al., 1998), although the majority of the 
population is found over the continental shelf (Hayes et al., 2022). 
Based on genetic analysis, it is assumed that harbor porpoises in U.S. 
and Canadian waters are divided into four populations, as follows: (1) 
Gulf of St. Lawrence; (2) Newfoundland; (3) Greenland; and (4) Gulf of 
Maine/Bay of Fundy (Hayes et al., 2022). For management purposes in 
U.S. waters, harbor porpoises have been divided into ten stocks along 
both the East and West Coasts. 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 (492 ft) deep (Hayes et al., 2022).
    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, 2018). Two harbor porpoises were observed during construction 
monitoring that occurred between January 2018 and January 2019 
(Cianbro, 2018; 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 a harbor porpoise during P-310 year 1 
monitoring events (May through December 2020) (NAVFAC, 2021). No harbor 
porpoise were sighted in 2021 (NAVFAC, 2022).

Harbor Seal

    Harbor seals are found in all nearshore waters of the North 
Atlantic and North Pacific Oceans and adjoining seas above about 
30[deg] N (Burns, 2009). They can be found year-round in coastal waters 
of eastern Canada and Maine and occur seasonally (September through 
late May) along the coasts of southern New England to Virginia (Ampela 
et al., 2018; Hayes et al., 2022; Jones and Rees, 2020). Overall, there 
are five recognized subspecies of harbor seal, two of which occur in 
the Atlantic Ocean. The western Atlantic harbor seal is the subspecies 
likely to occur in the proposed project area. There is some uncertainty 
about the overall population stock structure of harbor seals in the 
western North Atlantic Ocean. However, it is theorized that harbor 
seals along the eastern U.S. and Canada are all from a single 
population (Temte et al., 1991). Haulout and pupping sites are located

[[Page 3157]]

off Manomet, MA and the Isles of Shoals, ME (Hayes et al., 2022).
    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 Navy's application), which is located approximately 14.5 km (9 
mi) from the project area. There are no major rookeries near the Navy's 
proposed project area. The closest haul-out site is at Hicks Rocks, 
located approximately 2.4 km (1.5 mi) from the proposed project area, 
but it is on the opposite side of Seavey Island and not within the 
project area. Pupping season for harbor seals is May to June. No harbor 
seal pups were observed during recent monitoring events conducted in 
the area (Cianbro, 2018) as pupping sites are north of the Maine-New 
Hampshire border (Hayes et al., 2022). During construction monitoring 
between the months of April and December 2017, there were 199 
observations of harbor seals (Cianbro, 2018) in the project area. A 
total of 249 harbor seals were observed during construction monitoring 
between the months of January 2018 and January 2019 for the same 
project (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, 2018). 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). 
Construction monitoring conducted between May and December of 2020 and 
January through December 2021 as part of P-310 recorded 721 harbor 
seals and 451 harbor seals, respectively (NAVFAC, 2021; 2022).

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., 2022). 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., 2022). It 
is believed that recolonization by Canadian gray seals is the source of 
the U.S. population (Hayes et al., 2022).
    In U.S. waters, gray seals have been observed using an historic 
pupping site on Muskeget Island in Massachusetts since 1988 and on Seal 
and Green Islands in Maine since approximately the mid-1990s. All of 
these sites are more than 180 km (112 mi) from the Shipyard. In 
general, this species can be found year-round in the coastal waters of 
the Gulf of Maine (Hayes et al., 2022).
    During construction monitoring for the waterfront improvements 
project, there were 24 observations of gray seals within the proposed 
project area between the months of April and December 2017 (Cianbro, 
2018) and a total of 12 observed between January 2018 and January 2019 
(Navy, 2019). Ten of the 12 observations 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, 2018). 
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). In 2021, 21 gray seals were sighted during monitoring (NAVFAC, 
2022). No gray seal pups were observed during the surveys (Cianbro, 
2018; Navy, 2019) as pupping sites for gray seals (like harbor seals) 
are known to occur north of Maine-New Hampshire border.

Hooded Seal

    Hooded seals 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 (Hayes et 
al., 2022). 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 (Hayes et al., 2022). 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 (Hayes et al., 2022).
    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, 2020, or 2021 (Cianbro, 2018; NAVFAC Mid-Atlantic 
2018, 2019b; Navy 2019; NAVFAC 2021, 2022).

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 (Hayes 
et al., 2022).
    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. Two harp seals were 
sighted on two separate occasions (on May 12 and May 14, 2020) during 
construction monitoring for P-310 (Stantec, 2020). 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, 2016). Harp 
seals were not observed during marine mammal monitoring or survey 
events that took place in 2017 and 2018 (Cianbro, 2018; NAVFAC Mid-
Atlantic, 2018, 2019b; Navy, 2019). No harp seals were sighted in 2021 
(NAVFAC, 2021, 2022).

Unusual Mortality Events (UMEs)

    Between July 2018 and March 2020 elevated numbers of harbor seal 
and gray seal mortalities occurred across Maine, New Hampshire and 
Massachusetts. This event was declared an Unusual Mortality Event 
(UME). Seals showing clinical signs were observed stranding as far 
south as Virginia, although not in elevated numbers. Therefore the UME 
investigation encompassed all seal strandings from Maine to Virginia. 
Lastly, ice seals (harp and hooded seals) also started stranding with 
clinical

[[Page 3158]]

signs, again not in elevated numbers, and those two seal species were 
added to this UME investigation. 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.
    Since July 2022, a second UME of harbor seals and gray seals in 
this region has been declared after elevated numbers of sick and dead 
individuals were documented along the southern and central coast of 
Maine from Biddeford to Boothbay (including Cumberland, Lincoln, Knox, 
Sagadahoc and York Counties). Information on this UME is available 
online at: https://www.fisheries.noaa.gov/2022-pinniped-unusual-mortality-event-along-maine-coast.

Marine Mammal Hearing

    Hearing is the most important sensory modality for marine mammals 
underwater, and exposure to anthropogenic sound can have deleterious 
effects. To appropriately assess the potential effects of exposure to 
sound, it is necessary to understand the frequency ranges marine 
mammals are able to hear. Not all marine mammal species have equal 
hearing capabilities (e.g., Richardson et al., 1995; Wartzok and 
Ketten, 1999; Au and Hastings, 2008). To reflect this, Southall et al. 
(2007, 2019) recommended that marine mammals be divided into hearing 
groups based on directly measured (behavioral or auditory evoked 
potential techniques) or estimated hearing ranges (behavioral response 
data, anatomical modeling, etc.). Note that no direct measurements of 
hearing ability have been successfully completed for mysticetes (i.e., 
low-frequency cetaceans). Subsequently, NMFS (2018a) 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 (dolphins,      150 Hz to 160 kHz.
 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) (true     50 Hz to 86 kHz.
 seals).
Otariid pinnipeds (OW) (underwater) (sea     60 Hz to 39 kHz.
 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 (2018a) for a review of available information.

Potential Effects of Specified Activities on Marine Mammals and Their 
Habitat

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

Description of Sound Sources

    This section contains a brief technical background on sound, on the 
characteristics of certain sound types, and on metrics used in this 
proposal inasmuch as the information is relevant to the specified 
activity and to a discussion of the potential effects of the specified 
activity on marine mammals found later in this document. For general 
information on sound and its interaction with the marine environment, 
please see, e.g., Au and Hastings (2008); Richardson et al. (1995); 
Urick (1983).
    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 or corresponding points of a sound wave 
(length of one cycle). Higher frequency sounds have shorter wavelengths 
than lower frequency sounds, and typically attenuate (decrease) more 
rapidly, except in certain cases in shallower water. Amplitude is the 
height of the sound pressure wave or the ``loudness'' of a sound and is 
typically described using the relative unit of the dB. A sound pressure 
level (SPL) in dB is described as the ratio between a measured pressure 
and a reference pressure (for underwater sound, this is 1 microPascal 
([mu]Pa)), and is a logarithmic unit that accounts for large variations 
in amplitude; therefore, a relatively small change in dB corresponds to 
large changes in sound pressure. The source level represents the SPL 
referenced at a distance of 1 m from the source (referenced to 1 
[mu]Pa), while the received level is the SPL at

[[Page 3159]]

the listener's position (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.
    Sound exposure level (SEL; represented as dB referenced to 1 
micropascal squared per second (re 1 [mu]Pa2-s)) represents the total 
energy in a stated frequency band over a stated time interval or event, 
and considers both intensity and duration of exposure. The per-pulse 
SEL is calculated over the time window containing the entire pulse 
(i.e., 100 percent of the acoustic energy). SEL is a cumulative metric; 
it can be accumulated over a single pulse, or calculated over periods 
containing multiple pulses. Cumulative SEL (SELcum) represents the 
total energy accumulated by a receiver over a defined time window or 
during an event. Peak sound pressure (also referred to as zero-to-peak 
sound pressure or 0-pk) is the maximum instantaneous sound pressure 
measurable in the water at a specified distance from the source, and is 
represented in the same units as the RMS sound pressure.
    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 a 
manner similar to ripples on the surface of a pond and may be either 
directed in a beam or beams or may radiate in all directions 
(omnidirectional sources), as is the case for sound produced by the 
construction activities considered here. 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, which is 
defined as the all-encompassing sound in a given place and is usually a 
composite of sound from many sources both near and far (American 
National Standards Institute standards (ANSI), 1995). 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., 
wind and waves, earthquakes, ice, atmospheric sound), biological (e.g., 
sounds produced by marine mammals, fish, and invertebrates), and 
anthropogenic (e.g., vessels, dredging, construction) sound. A number 
of sources contribute to ambient sound, including wind and waves, which 
are a main source of naturally occurring ambient sound 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. Precipitation can become an important component of total 
sound at frequencies above 500 Hz, and possibly down to 100 Hz during 
quiet times. Marine mammals can contribute significantly to ambient 
sound levels, as can some fish and snapping shrimp. The frequency band 
for biological contributions is from approximately 12 Hz to over 100 
kHz. Sources of ambient sound related to human activity include 
transportation (surface vessels), dredging and construction, oil and 
gas drilling and production, geophysical surveys, sonar, and 
explosions. Vessel noise typically dominates the total ambient sound 
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.
    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. 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 belts, heating, air 
conditioning, and ventilation 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, 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). Thirteen underwater acoustic recordings 
were logged in 2017 with sensors placed in depths of 4.5 m (15 ft) 
within the security fencing area of the Shipyard Berth 11. Recordings 
ranged from 140 dB to 161.3 dB peak SPL and from 128.2 dB to 133.8 dB 
RMS SPL. Conditions at which the recordings were made were with little 
wind and near peak tidal flow. A mean SPL of 131 dB RMS was evenly 
distributed within the security fencing area and is consistent with 
observations made at other locations near the Shipyard and documented 
background sound levels in estuarine or tidal locations (Hydrosonic 
LLC, 2017). Due to the close proximity to the Shipyard that 
measurements were recorded, ambient underwater noise levels further 
into the navigation channel are likely to be lower.
    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.
    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

[[Page 3160]]

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 
(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.
    Impact and vibratory hammers would be used on this project. Impact 
hammers operate by repeatedly dropping and/or pushing a heavy piston 
onto a pile to drive the pile into the substrate. Sound generated by 
impact hammers is characterized by rapid rise times and high peak 
levels, a potentially injurious combination (Hastings and Popper, 
2005). Vibratory hammers install piles by vibrating them and allowing 
the weight of the hammer to push them into the sediment. Vibratory 
hammers produce significantly less sound than impact hammers. Peak SPLs 
may be 180 dB or greater, but are generally 10 to 20 dB lower than SPLs 
generated during impact pile driving of the same-sized pile (Oestman et 
al., 2009). Rise time is slower, reducing the probability and severity 
of injury, and sound energy is distributed over a greater amount of 
time (Nedwell and Edwards, 2002; Carlson et al., 2005). Vibratory pile 
drivers will be used to the greatest extent possible during the Navy's 
proposed construction activities to minimize high SPLs associated with 
impact pile driving.
    Hydraulic rock hammers (i.e., hoe rams) will be used for removal 
and demolition purposes. These tools are impact devices designed to 
break rock or concrete. A rock hammer operates by using a chisel-like 
hammer to rapidly strike an exposed surface to break it up into smaller 
pieces that will be removed by a clamshell dredge or bucket excavator, 
as appropriate. Few data exist regarding the underwater sounds produced 
by rock hammers. Data reported by Escude (2012), however, suggest that 
the sounds produced by hoe rams are comparable to impact hammers. 
Therefore, for the purposes of this analysis, it is assumed that 
hydraulic rock hammers act as an impulsive source characterized by 
rapid rise times and high peak levels.
    DTH systems, involving both mono-hammers and cluster-hammers, and 
rotary drills will also be used during the proposed construction. In 
rotary drilling, the drill bit rotates on the rock while the drill rig 
applies pressure. The bit rotates and grinds continuously to fracture 
the rock and create a hole. Rotary drilling is considered a non-
impulsive noise source, similar to vibratory pile driving. A DTH hammer 
is essentially a drill bit that drills through the bedrock using a 
rotating function like a normal drill, in concert with a hammering 
mechanism operated by a pneumatic (or sometimes hydraulic) component 
integrated into to the DTH hammer to increase speed of progress through 
the substrate (i.e., it is similar to a ``hammer drill'' hand tool). 
Rock socketing involves using DTH equipment to create a hole in the 
bedrock inside which the pile is placed to give it lateral and 
longitudinal strength. The sounds produced by the DTH methods contain 
both a continuous non-impulsive component from the drilling action and 
an impulsive component from the hammering effect. Therefore, we treat 
DTH systems as both impulsive and continuous, non-impulsive sound 
source types simultaneously.
    The likely or possible impacts of the Navy's proposed activities on 
marine mammals could involve both non-acoustic and acoustic stressors. 
Potential non-acoustic stressors could result from the physical 
presence of the equipment and personnel; however, given there are no 
known pinniped haul-out sites in the vicinity of the Shipyard, visual 
and other non-acoustic stressors would be limited, and any impacts to 
marine mammals are expected to primarily be acoustic in nature.

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, 2019). 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, 2018a). The amount of 
threshold shift is customarily expressed in dB. A TS can be permanent 
or temporary. As described in NMFS (2018a), 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.,

[[Page 3161]]

how animal uses sound within the frequency band of the signal; e.g., 
Kastelein et al., 2014), and the overlap between the animal and the 
source (e.g., spatial, temporal, and spectral). When analyzing the 
auditory effects of noise exposure, it is often helpful to broadly 
categorize sound as either impulsive or non-impulsive. When considering 
auditory effects, vibratory pile driving and rotary drilling are 
considered non-impulsive sources while impact pile driving and rock 
hammering are treated as an impulsive source. DTH is considered to have 
both non-impulsive and impulsive components.
    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)--A temporary, reversible increase 
in the threshold of audibility at a specified frequency or portion of 
an individual's hearing range above a previously established reference 
level (NMFS, 2018). Based on data from cetacean TTS measurements (see 
Southall et al. 2007), a TTS of 6 dB is considered the minimum 
threshold shift clearly larger than any day-to-day or session-to-
session variation in a subject's normal hearing ability (Schlundt et 
al., 2000; Finneran et al., 2000, 2002). As described in Finneran 
(2015), marine mammal studies have shown the amount of TTS increases 
with SELcum in an accelerating fashion: at low exposures with lower 
SELcum, the amount of TTS is typically small and the growth curves have 
shallow slopes. At exposures with higher SELcum, the growth curves 
become steeper and approach linear relationships with the noise SEL.
    Depending on the degree (elevation of threshold in dB), duration 
(i.e., recovery time), and frequency range of TTS, and the context in 
which it is experienced, TTS can have effects on marine mammals ranging 
from discountable to serious (similar to those discussed in auditory 
masking, below). For example, a marine mammal may be able to readily 
compensate for a brief, relatively small amount of TTS in a non-
critical frequency range that takes place during a time when the animal 
is traveling through the open ocean, where ambient noise is lower and 
there are not as many competing sounds present. Alternatively, a larger 
amount and longer duration of TTS sustained during time when 
communication is critical for successful mother/calf interactions could 
have more serious impacts. We note that reduced hearing sensitivity as 
a simple function of aging has been observed in marine mammals, as well 
as humans and other taxa (Southall et al., 2007), so we can infer that 
strategies exist for coping with this condition to some degree, though 
likely not without cost.
    Relationships between TTS and PTS thresholds have not been studied 
in marine mammals, and there is no PTS data for cetaceans, but such 
relationships are assumed to be similar to those in humans and other 
terrestrial mammals. PTS typically occurs at exposure levels at least 
several decibels above (a 40-dB threshold shift approximates PTS onset; 
e.g., Kryter et al., 1966; Miller, 1974) that inducing mild TTS (a 6-dB 
threshold shift approximates TTS onset; e.g., Southall et al., 2007). 
Based on data from terrestrial mammals, a precautionary assumption is 
that the PTS thresholds for impulsive sounds (such as impact pile 
driving pulses as received close to the source) are at least 6 dB 
higher than the TTS threshold on a peak-pressure basis and PTS 
cumulative sound exposure level thresholds are 15 to 20 dB higher than 
TTS cumulative sound exposure level thresholds (Southall et al., 2007). 
Given the higher level of sound or longer exposure duration necessary 
to cause PTS as compared with TTS, it is considerably less likely that 
PTS could occur.
    TTS is the mildest form of hearing impairment that can occur during 
exposure to sound (Kryter, 1985). While experiencing TTS, the hearing 
threshold rises, and a sound must be at a higher level in order to be 
heard. In terrestrial and marine mammals, TTS can last from minutes or 
hours to days (in cases of strong TTS). In many cases, hearing 
sensitivity recovers rapidly after exposure to the sound ends. 
Currently, TTS data only exist for four species of cetaceans 
(bottlenose dolphin), 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 (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 and harbor porpoises 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. No data 
are 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), Finneran (2015), and Table 5 in NMFS (2018).
    Behavioral Harassment--Exposure to noise from pile driving and 
drilling also has the potential to behaviorally disturb marine mammals. 
Behavioral disturbance may include a variety of effects, including 
subtle changes in behavior (e.g., minor or brief avoidance of an area 
or changes in vocalizations), more conspicuous changes in similar 
behavioral activities, and more sustained and/or potentially severe 
reactions, such as displacement from or abandonment of high-quality 
habitat. Disturbance may result in changing durations of surfacing and 
dives, changing direction and/or speed; reducing/increasing vocal 
activities; changing/cessation of certain behavioral activities (such 
as socializing or feeding); eliciting a visible startle response or 
aggressive behavior (such as tail/fin 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

[[Page 3162]]

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 and C of 
Southall et al. (2007) and Gomez et al. (2016) for reviews of studies 
involving marine mammal behavioral responses to sound.
    Habituation can occur when an animal's response to a stimulus wanes 
with repeated exposure, usually in the absence of unpleasant associated 
events (Wartzok et al., 2003). Animals are most likely to habituate to 
sounds that are predictable and unvarying. It is important to note that 
habituation is appropriately considered as a ``progressive reduction in 
response to stimuli that are perceived as neither aversive nor 
beneficial,'' rather than as, more generally, moderation in response to 
human disturbance (Bejder et al., 2009). The opposite process is 
sensitization, when an unpleasant experience leads to subsequent 
responses, often in the form of avoidance, at a lower level of 
exposure.
    As noted above, behavioral state may affect the type of response. 
For example, animals that are resting may show greater behavioral 
change in response to disturbing sound levels than animals that are 
highly motivated to remain in an area for feeding (Richardson et al., 
1995; National Research Council (NRC), 2003; Wartzok et al., 2003). 
Controlled experiments with captive marine mammals have showed 
pronounced behavioral reactions, including avoidance of loud sound 
sources (Ridgway et al., 1997; Finneran et al., 2003). Observed 
responses of wild marine mammals to loud pulsed sound sources 
(typically seismic airguns or acoustic harassment devices) have been 
varied but often consist of avoidance behavior or other behavioral 
changes suggesting discomfort (Morton and Symonds, 2002; see also 
Richardson et al., 1995; Nowacek et al., 2007).
    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). However, there are broad categories of potential response, which 
we describe in greater detail here, that include alteration of dive 
behavior, alteration of foraging behavior, effects to breathing, 
interference with or alteration of vocalization, avoidance, and flight.
    Changes in dive behavior can vary widely and may consist of 
increased or decreased dive times and surface intervals as well as 
changes in the rates of ascent and descent during a dive (e.g., Frankel 
and Clark, 2000; Costa et al., 2003; Ng and Leung, 2003; Nowacek et 
al., 2004; Goldbogen et al., 2013a,b). Variations in dive behavior may 
reflect interruptions in biologically significant activities (e.g., 
foraging) or they may be of little biological significance. The impact 
of an alteration to dive behavior resulting from an acoustic exposure 
depends on what the animal is doing at the time of the exposure and the 
type and magnitude of the response.
    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.
    Variations in respiration naturally vary with different behaviors 
and alterations to breathing rate as a function of acoustic exposure 
can be expected to co-occur with other behavioral reactions, such as a 
flight response or an alteration in diving. However, respiration rates 
in and of themselves may be representative of annoyance or an acute 
stress response. Various studies have shown that respiration rates may 
either be unaffected or could increase, depending on the species and 
signal characteristics, again highlighting the importance in 
understanding species differences in the tolerance of underwater noise 
when determining the potential for impacts resulting from anthropogenic 
sound exposure (e.g., Kastelein et al., 2001, 2005, 2006; Gailey et 
al., 2007).
    Marine mammals vocalize for different purposes and across multiple 
modes, such as whistling, echolocation click production, calling, and 
singing. Changes in vocalization behavior in response to anthropogenic 
noise can occur for any of these modes and may result from a need to 
compete with an increase in background noise or may reflect increased 
vigilance or a startle response. For example, in the presence of 
potentially masking signals, humpback whales and killer whales have 
been observed to increase the length of their songs (Miller et al., 
2000; Fristrup et al., 2003; Foote et al., 2004), while right whales 
(Eubalaena glacialis) have been observed to shift the frequency content 
of their calls upward while reducing the rate of calling in areas of 
increased anthropogenic noise (Parks et al., 2007). In some cases, 
animals may cease sound production during production of aversive 
signals (Bowles et al., 1994).
    Avoidance is the displacement of an individual from an area or 
migration path as a result of the presence of a sound or other 
stressors, and is one of the most obvious manifestations of disturbance 
in marine mammals (Richardson et al., 1995). For example, gray whales 
are known to change direction--deflecting from customary migratory 
paths--in order to avoid noise from seismic surveys (Malme et al., 
1984). Avoidance may be short-term, with animals returning to the area 
once the noise has ceased (e.g., Bowles et al., 1994; Goold, 1996; 
Stone et al., 2000; Morton and Symonds, 2002; Gailey et al., 2007). 
Longer-term displacement is possible, however, which may lead to 
changes in abundance or distribution patterns of the affected species 
in the affected region if habituation to the presence of the sound does 
not occur (e.g., Blackwell et al., 2004; Bejder et al., 2006; Teilmann 
et al., 2006).
    A flight response is a dramatic change in normal movement to a 
directed and rapid movement away from the perceived location of a sound 
source. The flight response differs from other avoidance responses in 
the intensity of the response (e.g., directed movement, rate of 
travel). Relatively little information on flight responses of marine 
mammals to anthropogenic signals exist, although observations of flight 
responses to the presence of predators have occurred (Connor and

[[Page 3163]]

Heithaus, 1996, Bowers et al., 2018). The result of a flight response 
could range from brief, temporary exertion and displacement from the 
area where the signal provokes flight to, in extreme cases, marine 
mammal strandings (Evans and England, 2001). However, it should be 
noted that response to a perceived predator does not necessarily invoke 
flight (Ford and Reeves, 2008), and whether individuals are solitary or 
in groups may influence the response.
    Behavioral disturbance can also impact marine mammals in more 
subtle ways. Increased vigilance may result in costs related to 
diversion of focus and attention (i.e., when a response consists of 
increased vigilance, it may come at the cost of decreased attention to 
other critical behaviors such as foraging or resting). These effects 
have generally not been demonstrated for marine mammals, but studies 
involving fish and terrestrial animals have shown that increased 
vigilance may substantially reduce feeding rates (e.g., Beauchamp and 
Livoreil, 1997; Fritz et al., 2002; Purser and Radford, 2011). In 
addition, chronic disturbance can cause population declines through 
reduction of fitness (e.g., decline in body condition) and subsequent 
reduction in reproductive success, survival, or both (e.g., Harrington 
and Veitch, 1992; Daan et al., 1996; Bradshaw et al., 1998). However, 
Ridgway et al. (2006) reported that increased vigilance in bottlenose 
dolphins exposed to sound over a 5-day period did not cause any sleep 
deprivation or stress effects.
    Many animals perform vital functions, such as feeding, resting, 
traveling, and socializing, on a diel cycle (24-hour cycle). Disruption 
of such functions resulting from reactions to stressors such as sound 
exposure are more likely to be significant if they last more than one 
diel cycle or recur on subsequent days (Southall et al., 2007). 
Consequently, a behavioral response lasting less than one day and not 
recurring on subsequent days is not considered particularly severe 
unless it could directly affect reproduction or survival (Southall et 
al., 2007). Note that there is a difference between multi-day 
substantive behavioral reactions and multi-day anthropogenic 
activities. For example, just because an activity lasts for multiple 
days does not necessarily mean that individual animals are either 
exposed to activity-related stressors for multiple days or, further, 
exposed in a manner resulting in sustained multi-day substantive 
behavioral responses.
    Stress responses--An animal's perception of a threat may be 
sufficient to trigger stress responses consisting of some combination 
of behavioral responses, autonomic nervous system responses, 
neuroendocrine responses, or immune responses (e.g., Seyle, 1950; 
Moberg, 2000). In many cases, an animal's first and sometimes most 
economical (in terms of energetic costs) response is behavioral 
avoidance of the potential stressor. Autonomic nervous system responses 
to stress typically involve changes in heart rate, blood pressure, and 
gastrointestinal activity. These responses have a relatively short 
duration and may or may not have a significant long-term effect on an 
animal's fitness.
    Neuroendocrine stress responses often involve the hypothalamus-
pituitary-adrenal system. Virtually all neuroendocrine functions that 
are affected by stress--including immune competence, reproduction, 
metabolism, and behavior--are regulated by pituitary hormones. Stress-
induced changes in the secretion of pituitary hormones have been 
implicated in failed reproduction, altered metabolism, reduced immune 
competence, and behavioral disturbance (e.g., Moberg, 1987; Blecha, 
2000). Increases in the circulation of glucocorticoids are also equated 
with stress (Romano et al., 2004).
    The primary distinction between stress (which is adaptive and does 
not normally place an animal at risk) and ``distress'' is the cost of 
the response. During a stress response, an animal uses glycogen stores 
that can be quickly replenished once the stress is alleviated. In such 
circumstances, the cost of the stress response would not pose serious 
fitness consequences. However, when an animal does not have sufficient 
energy reserves to satisfy the energetic costs of a stress response, 
energy resources must be diverted from other functions. This state of 
distress will last until the animal replenishes its energetic reserves 
sufficient to restore normal function.
    Relationships between these physiological mechanisms, animal 
behavior, and the costs of stress responses are well-studied through 
controlled experiments and for both laboratory and free-ranging animals 
(e.g., Holberton et al., 1996; Hood et al., 1998; Jessop et al., 2003; 
Krausman et al., 2004; Lankford et al., 2005). Stress responses due to 
exposure to anthropogenic sounds or other stressors and their effects 
on marine mammals have also been reviewed (Fair and Becker, 2000; 
Romano et al., 2002b) and, more rarely, studied in wild populations 
(e.g., Romano et al., 2002a). For example, Rolland et al. (2012) found 
that noise reduction from reduced ship traffic in the Bay of Fundy was 
associated with decreased stress in North Atlantic right whales. These 
and other studies lead to a reasonable expectation that some marine 
mammals will experience physiological stress responses upon exposure to 
acoustic stressors and that it is possible that some of these would be 
classified as ``distress.'' In addition, any animal experiencing TTS 
would likely also experience stress responses (NRC, 2003), however 
distress is an unlikely result of this project based on observations of 
marine mammals during previous, similar construction projects.
    Auditory Masking--Since many marine mammals rely on sound to find 
prey, moderate social interactions, and facilitate mating (Tyack, 
2008), noise from anthropogenic sound sources can interfere with these 
functions, but only if the noise spectrum overlaps with the hearing 
sensitivity of the marine mammal (Southall et al., 2007; Clark et al., 
2009; Hatch et al., 2012). Chronic exposure to excessive, though not 
high-intensity, noise could cause masking at particular frequencies for 
marine mammals that utilize sound for vital biological functions (Clark 
et al., 2009). Acoustic masking is when other noises such as from human 
sources interfere 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; Erbe et al., 
2016). Therefore, under certain circumstances, marine mammals whose 
acoustical sensors or environment are being severely masked could also 
be impaired from maximizing their performance fitness in survival and 
reproduction. 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.
    Under certain circumstances, marine mammals experiencing 
significant masking could also be impaired from maximizing their 
performance fitness in survival and reproduction. Therefore, when the 
coincident (masking) sound is man-made, it may be considered harassment 
when disrupting or altering critical behaviors. It is important to 
distinguish TTS and PTS, which persist after the sound exposure, from 
masking, which occurs during the sound

[[Page 3164]]

exposure. Because masking (without resulting in TS) is not associated 
with abnormal physiological function, it is not considered a 
physiological effect, but rather a potential behavioral effect.
    The frequency range of the potentially masking sound is important 
in determining any potential behavioral impacts. For example, low-
frequency signals may have less effect on high-frequency echolocation 
sounds produced by odontocetes but are more likely to affect detection 
of mysticete communication calls and other potentially important 
natural sounds such as those produced by surf and some prey species. 
The masking of communication signals by anthropogenic noise may be 
considered as a reduction in the communication space of animals (e.g., 
Clark et al., 2009) and may result in energetic or other costs as 
animals change their vocalization behavior (e.g., Miller et al., 2000; 
Foote et al., 2004; Parks et al., 2007; Di Iorio and Clark, 2009; Holt 
et al., 2009). Masking can be reduced in situations where the signal 
and noise come from different directions (Richardson et al., 1995), 
through amplitude modulation of the signal, or through other 
compensatory behaviors (Houser and Moore, 2014). Masking can be tested 
directly in captive species (e.g., Erbe, 2008), but in wild populations 
it must be either modeled or inferred from evidence of masking 
compensation. There are few studies addressing real-world masking 
sounds likely to be experienced by marine mammals in the wild (e.g., 
Branstetter et al., 2013).
    Marine mammals in the Piscataqua River are exposed to anthropogenic 
noise which may lead to some habituation, but is also a source of 
masking. Vocalization changes may result from a need to compete with an 
increase in background noise and include increasing the source level, 
modifying the frequency, increasing the call repetition rate of 
vocalizations, or ceasing to vocalize in the presence of increased 
noise (Hotchkin and Parks, 2013).
    Masking is more likely to occur in the presence of broadband, 
relatively continuous noise sources. Energy distribution of pile 
driving covers a broad frequency spectrum, and sound from pile driving 
would be within the audible range of pinnipeds and cetaceans present in 
the proposed action area. While some construction during the Navy's 
activities may mask some acoustic signals that are relevant to the 
daily behavior of marine mammals, the short-term duration and limited 
areas affected make it very unlikely that survival would be affected.
    Airborne Acoustic Effects--Pinnipeds that occur near the project 
site could be exposed to airborne sounds associated with construction 
activities that have the potential to cause behavioral harassment, 
depending on their distance from these activities. Airborne noise would 
primarily be an issue for pinnipeds that are swimming or hauled out 
near the project site within the range of noise levels elevated above 
airborne acoustic criteria. 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 
(e.g., Hicks Rocks located on the opposite side of the island where 
activities are occurring). Cetaceans are not expected to be exposed to 
airborne sounds that would result in harassment as defined under the 
MMPA.
    We recognize that pinnipeds in the water could be exposed to 
airborne sound that may result in behavioral harassment when looking 
with their heads above water. Most likely, airborne sound would cause 
behavioral responses similar to those discussed above in relation to 
underwater sound. For instance, anthropogenic sound could cause hauled-
out pinnipeds to exhibit changes in their normal behavior, such as 
reduction in vocalizations, or cause them to temporarily abandon the 
area and move further from the source. However, these animals would 
previously have been `taken' because of exposure to underwater sound 
above the behavioral harassment thresholds, which are in all cases 
larger than those associated with airborne sound. Thus, the behavioral 
harassment of these animals is already accounted for in these estimates 
of potential take. Therefore, we do not believe that authorization of 
incidental take resulting from airborne sound for pinnipeds is 
warranted, and airborne sound is not discussed further here.

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 and removal of piles and 
bedrock removal when bottom sediments are disturbed. The installation 
and removal of piles and bedrock removal and dredging 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 milligrams per liter (mg/L) above background 
levels within approximately 91 m (300 ft) of the pile being driven 
(Federal Highway Administration, 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.
    TSS concentrations associated with mechanical clamshell bucket 
dredging operations have been shown to range from 105 mg/L in the 
middle of the water column to 445 mg/L near the bottom (210 mg/L, 
depth-averaged) (Army Corps of Engineers, 2001). Furthermore, a study 
by Burton (1993) measured TSS concentrations at distances of 152, 305, 
610, and 1006 m (500, 1,000, 2,000, and 3,300 ft) from dredge sites in 
the Delaware River and were able to detect concentrations between 15 
mg/L and 191 mg/L up to 610 m (2,000 ft) from the dredge site. In 
support of the New York/New Jersey Harbor Deepening Project, the U.S. 
Army Corps of Engineers conducted extensive monitoring of mechanical 
dredge plumes (Army Corps of Engineers, 2015). Independent of bucket

[[Page 3165]]

type or size, plumes dissipated to background levels within 183 m (600 
ft) of the source in the upper water column and 732 m (2,400 ft) in the 
lower water column. Based on these studies, elevated suspended sediment 
concentrations at several hundreds of mg/L above background may be 
present in the immediate vicinity of the bucket, but would settle 
rapidly within a 732 m (2,400 ft) radius of the dredge location. The 
TSS levels expected for mechanical dredging (up to 445.0 mg/L) are 
below those shown to have adverse effect on fish (typically up to 
1,000.0 mg/L; see summary of scientific literature in Burton 1993, 
Wilber and Clarke 2001).
    Effects to turbidity and sedimentation are expected to be short-
term, minor, and localized. Since the currents are so strong in the 
area, following the completion of sediment-disturbing activities, 
suspended sediments in the water column should dissipate and quickly 
return to background levels in all construction scenarios. 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. In general, the area likely impacted by the 
proposed construction activities is relatively small compared to the 
available marine mammal habitat in Great Bay Estuary.
    Potential Effects on Prey--Sound may affect marine mammals through 
impacts 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 and Mann, 1999; Fay, 
2009). Depending on their hearing anatomy and peripheral sensory 
structures, which vary among species, fishes hear sounds using pressure 
and particle motion sensitivity capabilities and detect the motion of 
surrounding water (Fay et al., 2008). The potential effects of noise on 
fishes depends on the overlapping frequency range, distance from the 
sound source, water depth of exposure, and species-specific hearing 
sensitivity, anatomy, and physiology. Key impacts to fishes may include 
behavioral responses, hearing damage, barotrauma (pressure-related 
injuries), and mortality.
    Fish react to sounds that are especially strong and/or intermittent 
low-frequency sounds. Short duration, sharp sounds can cause overt or 
subtle changes in fish behavior and local distribution. The reaction of 
fish to noise depends on the physiological state of the fish, past 
exposures, motivation (e.g., feeding, spawning, migration), and other 
environmental factors. Hastings and Popper (2005) identified several 
studies that suggest fish may relocate to avoid certain areas of sound 
energy. Additional studies have documented effects of pile driving on 
fish; several are based on studies in support of large, multiyear 
bridge construction projects (e.g., Scholik and Yan, 2001, 2002; Popper 
and Hastings, 2009). Several studies have demonstrated that impulse 
sounds might affect the distribution and behavior of some fishes, 
potentially impacting foraging opportunities or increasing energetic 
costs (e.g., Fewtrell and McCauley, 2012; Pearson et al., 1992; Skalski 
et al., 1992; Santulli et al., 1999; Paxton et al., 2017). However, 
some studies have shown no or slight reaction to impulse sounds (e.g., 
Pena et al., 2013; Wardle et al., 2001; Jorgenson and Gyselman, 2009; 
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 (summarized in Popper et al., 2014). 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. In-water construction 
activities would only occur during daylight hours allowing fish to 
forage and transit the project area in the evening. Additionally, the 
Back Channel of the Piscataqua River would be unaffected by 
construction activities and would provide a pathway for unrestricted 
fish movement. 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 would have minimal permanent and temporary 
impacts on benthic invertebrate species, a marine mammal prey source. 
Benthic invertebrates that are commonly prey for marine mammals, such 
as squid species, were not detected during a 2014 benthic survey of the 
proposed project area (CR Environmental, Inc., 2014). The majority of 
direct benthic habitat loss previously occurred with the permanent loss 
of approximately 3.5 acres of benthic habitat from construction of the 
super flood basin (P-310). The water surface of Great Bay Estuary 
extends approximately 4.45 square mi (124,000,000 square ft) at low 
tide (Mills, No date). Therefore, that loss of approximately 152,000 
square ft represented approximately one-tenth of 1 percent of the 
benthic habitat in the estuary at low tide. Additional areas that would 
be permanently removed by the multifunctional expansion of Dry Dock 1 
(P- 381) are either previously impacted by P-310 construction 
activities or 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. 
Further, vessel activity at the berths creates minor disturbances of

[[Page 3166]]

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

Acoustic Thresholds

    NMFS recommends the use of acoustic thresholds that identify the 
received level of underwater sound above which exposed marine mammals 
would be reasonably expected to be behaviorally harassed (equated to 
Level B harassment) or to incur PTS of some degree (equated to Level A 
harassment).
    Level B Harassment--Though significantly driven by received level, 
the onset of behavioral disturbance from anthropogenic noise exposure 
is also informed to varying degrees by other factors related to the 
source or exposure context (e.g., frequency, predictability, duty 
cycle, duration of the exposure, signal-to-noise ratio, distance to the 
source), the environment (e.g., bathymetry, other noises in the area, 
predators in the area), and the receiving animals (hearing, motivation, 
experience, demography, life stage, depth) and can be difficult to 
predict (e.g., Southall et al., 2007, 2021, Ellison et al., 2012). 
Based on what the available science indicates and the practical need to 
use a threshold based on a metric that is both predictable and 
measurable for most activities, NMFS typically uses a generalized 
acoustic threshold based on received level to estimate the onset of 
behavioral harassment. NMFS generally predicts that marine mammals are 
likely to be behaviorally harassed in a manner considered to be Level B 
harassment when exposed to underwater anthropogenic noise above root-
mean-squared pressure received levels (RMS SPL) of 120 dB (referenced 
to 1 micropascal (re 1 [mu]Pa)) for continuous (e.g., vibratory pile-
driving, drilling) and above RMS SPL 160 dB re 1 [mu]Pa for non-
explosive impulsive (e.g., seismic airguns) or intermittent (e.g., 
scientific sonar) sources. Generally speaking, Level B harassment take 
estimates based on these behavioral harassment thresholds are expected 
to include any likely takes by TTS as, in most cases, the likelihood of 
TTS occurs at distances from the source less than those at which 
behavioral harassment is likely. TTS of a sufficient degree can 
manifest as behavioral harassment, as reduced hearing sensitivity and 
the potential reduced opportunities to detect important signals 
(conspecific communication, predators, prey) may result in changes in 
behavior patterns that would not otherwise occur.
    The Navy's proposed activity includes the use of continuous 
(vibratory pile driving/removal, rotary drilling) and intermittent 
(impact pile driving, rock hammering) sources, and therefore the RMS 
SPL thresholds of 120 and 160 dB re 1 [mu]Pa, respectively, are 
applicable. DTH systems have both continuous and intermittent 
components as discussed in the Description of Sound Sources section 
above. When evaluating Level B harassment, NMFS recommends treating DTH 
as a continuous source and applying the RMS SPL thresholds of 120 dB re 
1 [mu]Pa (see NMFS recommended guidance on DTH systems at https://media.fisheries.noaa.gov/2022-11/PUBLIC%20DTH%20Basic%20Guidance_November%202022.pdf; NMFS, 2022).
    Level A Harassment--NMFS' Technical Guidance for Assessing the 
Effects of Anthropogenic Sound on Marine Mammal Hearing (Version 2.0) 
(Technical Guidance, 2018) identifies dual criteria to assess auditory 
injury (Level A harassment) to five different marine mammal groups 
(based on hearing sensitivity) as a result of exposure to noise from 
two different types of sources (impulsive or non-impulsive). The Navy's 
proposed activity includes the use of impulsive (impact pile driving, 
rock hammering, DTH) and non-impulsive (vibratory pile driving/removal, 
rotary drilling, DTH) sources.
    These thresholds are provided in the table below. The references, 
analysis, and methodology used in the development of the thresholds are 
described in NMFS' 2018 Technical Guidance, which may be accessed at: 
www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance.

[[Page 3167]]



                     Table 5--Thresholds Identifying the Onset of Permanent Threshold Shift
----------------------------------------------------------------------------------------------------------------
                                                    PTS onset acoustic thresholds *  (received level)
             Hearing group              ------------------------------------------------------------------------
                                                  Impulsive                         Non-impulsive
----------------------------------------------------------------------------------------------------------------
Low-Frequency (LF) Cetaceans...........  Cell 1: Lpk,flat: 219 dB;   Cell 2: LE,LF,24h: 199 dB.
                                          LE,LF,24h: 183 dB.
Mid-Frequency (MF) Cetaceans...........  Cell 3: Lpk,flat: 230 dB;   Cell 4: LE,MF,24h: 198 dB.
                                          LE,MF,24h: 185 dB.
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.
Otariid Pinnipeds (OW) (Underwater)....  Cell 9: Lpk,flat: 232 dB;   Cell 10: LE,OW,24h: 219 dB.
                                          LE,OW,24h: 203 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 [micro]Pa, and cumulative sound exposure level (LE)
  has a reference value of 1[micro]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 (LF, MF, and HF cetaceans, and PW and OW 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 are used in estimating the area ensonified above the 
acoustic thresholds, including source levels and transmission loss 
coefficient.
    The sound field in the project area is the existing background 
noise plus additional construction noise from the proposed project. 
Marine mammals are expected to be affected via sound generated by the 
primary components of the project (i.e., impact pile driving, vibratory 
pile driving, vibratory pile removal, rotary drilling, rock hammering, 
and DTH).
    Sound Source Levels of Proposed Activities--The intensity of pile 
driving sounds is greatly influenced by factors such as the type of 
piles, hammers, and the physical environment (e.g., sediment type) in 
which the activity takes place. The Navy evaluated sound source level 
(SL) measurements available for certain pile types and sizes from 
similar environments from other Navy pile driving projects, including 
from past projects conducted at the Shipyard, and used them as proxy 
SLs to determine reasonable SLs likely to result from the pile driving 
and drilling activities in their application. 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. Some of the proxy source 
levels proposed by the Navy are expected to be more conservative as 
compared to what may be realized by the actual pile driving to take 
place, as the values are from larger pile sizes. In some instances, for 
reasons described below, NMFS relied on alternative proxy SLs in our 
evaluation of the impacts of the Navy's proposed activities on marine 
mammals (Table 6). Note that the source levels in this Table represent 
the SPL referenced at a distance of 10 m from the source.

                                          Table 6--Summary of Unattenuated In-Water Pile Driving Source Levels
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                           Peak SPL (dB re      RMS SPL (dB re 1        SELss (dB re 1
              Pile type                   Installation method          Pile diameter         1 [micro]Pa)          [micro]Pa)          [micro]Pa\2\ sec)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Casing/Socket........................  Rotary Drill............  126-inch................               NA  154 (169 at 1 m)........                  NA
                                                                 102-inch................               NA  154 (169 at 1 m)........                  NA
                                                                 84-inch.................               NA  154 (169 at 1 m)........                  NA
Shaft................................  DTH Cluster Drill.......  108-inch................               NA  201.6 \5\ (Level A).....                  NA
                                                                                                            174\6\ (Level B)........
                                                                 84-inch.................               NA  196.7 \5\ (Level A).....                  NA
                                                                                                            174 \6\ (Level B).......
                                                                 78-inch.................               NA  195.2 \5\ (Level A).....                 181
                                                                                                            174 \6\ (Level B).......
                                                                 72-inch.................               NA  193.7 \5\ (Level A).....                  NA
                                                                                                            174 \6\ (Level B).......
Rock anchor..........................  DTH mono-hammer.........  9-inch..................              172  167.....................                 146
Relief hole..........................  DTH mono-hammer.........  4 to 6-inch.............              170  156 \6\.................                 144
Z-shaped Sheet.......................  Impact..................  28-inch \1\.............              211  196.....................                 181
                                       Vibratory...............  28-inch \2\.............               NA  167.....................                 167
                                       Vibratory...............  25-inch \3\.............               NA  167.....................                 167
Bedrock and concrete demolition......  Rock Hammer \4\.........  NA......................              197  186 \4\.................             \4\ 171
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ An appropriate proxy value for impact driving 28-inch wide, Z-shaped sheet piles is not available, so a value for 30-inch steel pipe piles was used
  as a proxy value (NAVFAC SW, 2020 [p. A-4]).
\2\ An appropriate proxy value for vibratory pile driving 28-inch wide, Z-shaped sheet piles is not available, so a value for 30-inch steel pipe piles
  was used as a proxy value (Navy, 2015 [p. 14]).
\3\ An appropriate proxy value for vibratory pile driving 25-inch sheet piles is not available, so the value for 28-inch wide, Z-shaped sheet piles was
  used as a proxy.
\4\ Escude, 2012.
\5\ RMS SPL values were derived from regression and extrapolation calculations of existing data by NMFS.
\6\ SPLs vary from those proposed in the Navy's application as the NMFS DTH recommended guidance updated the source level proxy it recommends for some
  DTH systems after the Navy's application was deemed adequate and complete (NMFS, 2022).
Notes: All SPLs are unattenuated and represent the SPL referenced at a distance of 10 m from the source; NA = Not applicable; single strike SEL are the
  proxy source levels for impact pile driving used to calculate distances to PTS; dB re 1 [micro]Pa = decibels (dB) referenced to a pressure of 1
  microPascal, measures underwater SPL.; dB re 1 [micro]Pa\2\-sec = dB referenced to a pressure of 1 microPascal squared per second, measures underwater
  SEL.


[[Page 3168]]

    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, a proxy 
of 154 dB RMS is proposed for all rotary drilling activities (Dazey, 
2012).
    NMFS recommends treating DTH systems as both impulsive and 
continuous, non-impulsive sound source types simultaneously. Thus, 
impulsive thresholds are used to evaluate Level A harassment, and the 
continuous threshold is used to evaluate Level B harassment. The Navy 
consulted with NMFS to obtain the appropriate proxy values for DTH 
mono- and cluster-hammers. With regards to DTH mono-hammers, NMFS 
recommended proxy levels for Level A harassment based on available data 
regarding DTH systems of similar sized piles and holes (Table 6) (Denes 
et al., 2019; Guan and Miner, 2020; Reyff and Heyvaert, 2019; Reyff, 
2020; Heyvaert and Reyff, 2021). No hydroacoustic data exist for 
cluster DTH systems; therefore, NMFS recommends proxy values based off 
of regression and extrapolation calculations of existing data for mono-
hammers until hydroacoustic data on DTH cluster drills be obtained 
(NMFS, 2022). Because of the high number of hammers and strikes for 
this system, DTH cluster drills were treated as a continuous sound 
source for the time component of Level A harassment (i.e., for the 
entire duration DTH cluster drills are operational, they were 
considered to be producing strikes, rather than indicating the number 
of strikes per second, which was unknown), but still used the impulsive 
thresholds.
    At the time of the Navy's application submission, NMFS recommended 
that the RMS SPL at 10 m should be 167 dB when evaluating Level B 
harassment (Heyvaert and Reyff, 2021 as cited in NMFS, 2021b) for all 
DTH pile/hole sizes. However, since that time, NMFS has received 
additional clarifying information regarding DTH data presented in Reyff 
and Heyvaert (2019) and Reyff (2020) that allows for different RMS SPL 
at 10 m to be recommended for piles/holes of varying diameters (NMFS, 
2022). Therefore, NMFS proposes to use the following proxy RMS SPLs at 
10 m to evaluate Level B harassment from this sound source in this 
analysis (Table 6): 156 dB RMS for the 4 to 6 inch mono hammers (Reyff 
and Heyvaert, 2019; Reyff, 2020), 167 dB RMS for the 9 inch mono-
hammers (Heyvaert and Reyff, 2021), and 174 dB RMS for all DTH cluster 
drills greater or equal to 74 inches (Reyff and Heyvaert, 2019; Reyff, 
2020). See Footnote 6 to Table 6.
    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 Tables 1, 7, and 
8. As with rotary drilling, very little information is available 
regarding source levels associated with nearshore rock hammering. In 
previous IHAs related to the Shipyard, NMFS relied on preliminary 
measurements from the Tappan Zee Bridge replacement project (Reyff, 
2018a, 2018b) as well as data from a WSDOT concrete pier demolition 
project (Escude, 2012) to inform proxy SLs for rock hammering. However, 
a few discrepancies in the preliminary data of the Tappan Zee Bridge 
reports have been identified resulting from NMFS' further inspection 
into the report's data. Therefore, NMFS proposes to use the SLs 
reported only from the Escude (2012) concrete pier demolition project 
as proxy values for rock hammering activities associated with P-381 
(Table 6).
    Level B Harassment Zones--Transmission loss (TL) is the decrease in 
acoustic intensity as an acoustic pressure wave propagates out from a 
source. TL parameters vary with frequency, temperature, sea conditions, 
current, source and receiver depth, water depth, water chemistry, and 
bottom composition and topography. The general formula for underwater 
TL is:

TL = B * log10 (R1/R2),

Where:

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. The recommended TL coefficient for most nearshore 
environments is the practical spreading value of 15. This value results 
in an expected propagation environment that would lie between spherical 
and cylindrical spreading loss conditions, which is the most 
appropriate assumption for the Navy's proposed construction activities 
in the absence of specific modelling. All Level B harassment isopleths 
are reported in Tables 7 and 8 considering RMS SLs.
    Level A Harassment Zones--The ensonified area associated with Level 
A harassment is more technically challenging to predict due to the need 
to account for a duration component. Therefore, NMFS developed an 
optional User Spreadsheet tool to accompany the Technical Guidance that 
can be used to relatively simply predict an isopleth distance for use 
in conjunction with marine mammal density or occurrence to help predict 
potential takes. We note that because of some of the assumptions 
included in the methods underlying this optional tool, we anticipate 
that the resulting isopleth estimates are typically going to be 
overestimates of some degree, which may result in an overestimate of 
potential take by Level A harassment. However, this optional tool 
offers the best way to estimate isopleth distances when more 
sophisticated modeling methods are not available or practical. For 
stationary sources (such as from impact and vibratory pile driving, 
drilling, DTH, and rock hammering), the optional User Spreadsheet tool 
predicts the distance at which, if a marine mammal remained at that 
distance for the duration of the activity, it would be expected to 
incur PTS. Inputs used in the User Spreadsheet can be found in Appendix 
A of the Navy's application, Appendix A of the Navy's addendum, and the 
resulting isopleths are reported in Tables 7 and 8.

[[Page 3169]]



                              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 \2\           Level B harassment
                                                                                  Total    -------------------------------------------------------------
  Activity ID    Year \1\/ activity        Purpose          Duration, count,    production     High frequency
                                                           size, and or rate       days      cetaceans (harbor     Phocid pinnipeds       All species
                                                                                                 porpoise)
--------------------------------------------------------------------------------------------------------------------------------------------------------
1.............  2/Hydraulic Rock     Shutter Panel        5 hours/day (20               56  5,034.5 m/0.417417   2,261.9 m/0.417417   541.17 m/0.277858
                 Hammer.              Demolition (112      intervals/day at                  km\2\.               km\2\.               km\2\.
                                      panels).             15 each).
3.............  2-3/Hydraulic Rock   Removal of Granite   2.5 hours/day (10             47  3,171.6 m/0.417417   1,424.9 m/0.417417   541.17 m/0.277858
                 Hammer.              Quay Wall (2,800     intervals/day at                  km\2\.               km\2\.               km\2\.
                                      cy).                 15 min each).
4.............  2-3/Hydraulic Rock   Berth 1 Top of Wall  10 hours/day (40              74  7,991.8 m/0.417417   3,590.5 m/0.417417   541.17 m/0.277858
                 Hammer.              Demolition for       intervals/day at                  km\2\.               km\2\.               km\2\.
                                      Waler Install (320   15 min each).
                                      lf).
6.............  2/Hydraulic Rock     Mechanical Rock      12 hours/day (48              60  9,024.7 m/0.417417   4,054.5 m/0.417417   541.17 m/0.277858
                 Hammer.              Removal (700 cy)     intervals/day at                  km\2\.               km\2\.               km\2\.
                                      at Berth 11 Basin    15 min each).
                                      Floor.
10............  2/Hydraulic Rock     Mechanical Rock      12 hours/day (48              25  9,024.7 m/0.417417   4,054.5 m/0.417417   541.17 m/0.277858
                 Hammer.              Removal (300 cy)     intervals/day at                  km\2\.               km\2\.               km\2\.
                                      at Berth 1 Basin     15 min each).
                                      Floor.
21............  2/Hydraulic Rock     Removal of           4 hours/day (16               15  4,388.6 m/0.417417   1,949.2 m/0.417417   541.17 m/0.277858
                 Hammer.              Emergency Repair     intervals/day at                  km\2\.               km\2\.               km\2\.
                                      Concrete (500 cy)    15 min each).
                                      at Berth 1.
7.............  2/DTH Mono-hammer..  Relief Holes at      924 4-6 inch holes,           35  178.9 m/0.047675     80.4 m/0.014413      2,512 m/0. 417417
                                      Berth 11 Basin       27 holes/day.                     km\2\.               km\2\.               km\2\.
                                      Floor.
11............  2/DTH Mono-hammer..  Dry Dock 1 North     50 9-inch holes, 2            25  244.8 m/0.073751     110 m/0.022912       13,594 m/0.417417
                                      entrance Rock        holes/day.                        km\2\.               km\2\.               km\2\.
                                      Anchors.
22............  2-3/DTH Mono-hammer  Center Wall          72 9-inch holes, 2            36  244.8 m/0.073751     110 m/0.022912       13,594 m/0.417417
                                      Foundation Rock      holes/day.                        km\2\.               km\2\.               km\2\.
                                      Anchors.
34............  3-4 DTH Mono-hammer  Dry Dock 1 North     36 9-inch holes, 2            18  244.8 m/0.073751     110 m/0.022912       13,594 m/0.417417
                                      Rock Anchors.        holes/day.                        km\2\.               km\2\.               km\2\.
35............  4-5/DTH Mono-hammer  Dry Dock 1 West      36 9-inch holes, 2            18  244.8 m/0.073751     110 m/0.022912       13,594 m/0. 417417
                                      Rock Anchors.        holes/day.                        km\2\.               km\2\.               km\2\.
R.............  2/Impact Pile        Dry Dock 1 North     48 28-inch Z-shaped            6  1,568.6 m/0.417417   704.7 m/0.364953     2,512 m/0.417417
                 Driving.             Entrance Temporary   sheets, 8 sheets/                 km\2\.               km\2\.               km\2\.
                                      Cofferdam.           day.
5.............  2/Impact Pile        Berth 1 Support of   28 28-inch Z-shaped            8  988.2 m/0.403411     444.0 m/0.201158     2,512 m/0.417417
                 Driving.             Excavation.          sheets, 4 piles/                  km\2\.               km\2\.               km\2\.
                                                           day.
8.............  2/Impact Pile        Temporary Cofferdam  14 28-inch Z-shaped            4  988.2 m/0.403411     444.0 m/0.201158     2,512 m/0.417417
                 Driving.             Extension.           sheets, 4 piles/                  km\2\.               km\2\.               km\2\.
                                                           day.
12............  2/Impact Pile        Center Wall Tie-in   15 28-inch Z-shaped            4  988.2 m/0.403411     444.0 m/0.201158     2,512 m/0.417417
                 Driving.             to West Closure      sheets, 4 piles/                  km\2\.               km\2\.               km\2\.
                                      Wall.                day.
24............  2-3/Impact Pile      Center Wall East     23 28-inch Z-shaped           12  622.5 m/0.334747     279.7 m/0.090757     2,512 m/0.417417
                 Driving.             Tie-in to Existing   sheets, 2 piles/                  km\2\.               km\2\.               km\2\.
                                      Wall.                day.
A4............  2/DTH Cluster Drill  Dry Dock 1 North     18 78-inch shafts,           117  84,380.4 m/0.417417  37,909.7 m/0.417417  39,811 m/0.417417
                                      Entrance             10 hours/day, 6.5                 km\2\.               km\2\.               km\2\.
                                      Foundation Support   days/shaft.
                                      Piles.
9d............  2/DTH Cluster Drill  Gantry Crane         16 72-inch shafts,            80  67,025.7 m/0.417417  30,112.8 m/0.417417  39,811 m/0.417417
                                      Support Piles.       10 hours/day, 5                   km\2\.               km\2\.               km\2\.
                                                           days/shaft.
13d...........  2-3/DTH Cluster      Dry Dock 1 North     20 84-inch shafts,            70  106,228.6 m/         47,725.5 m/0.417417  39,811 m/0.417417
                 Drill.               Temporary Work       10 hours/day, 3.5                 0.417417 km\2\.      km\2\.               km\2\.
                                      Trestle.             days/shaft.
15d...........  2-3/DTH Cluster      Dry Dock 1 North     18 78-inch shafts,           135  84,380.4 m/0.417417  37,909.7 m/0.417417  39,811 m/0.417417
                 Drill.               Leveling Piles       10 hours/day, 7.5                 km\2\.               km\2\.               km\2\.
                                      (Diving Board        days/shaft.
                                      Shafts).
16d...........  2-3/DTH Cluster      Wall Shafts for Dry  20 78-inch shafts,           150  84,380.4 m/0.417417  37,909.7 m/0.417417  39,811 m/0.417417
                 Drill.               Dock 1 North.        10 hours/day, 7.5                 km\2\.               km\2\.               km\2\.
                                                           days/shaft.
17d...........  2-3/DTH Cluster      Foundation Shafts    23 108-inch shafts,          196  225,376.2 m/         101,255.2 m/         39,811 m/0.417417
                 Drill.               for Dry Dock 1       10 hours/day, 8.5                 0.417417 km\2\.      0.417417 km\2\.      km\2\.
                                      North.               days/shaft.
29d...........  3-4/DTH Cluster      Dry Dock 1 West      20 84-inch shafts,            70  106,228.6 m/         47,725.5 m/0.417417  39,811 m/0.417417
                 Drill.               Temporary Work       10 hours/day, 3.5                 0.417417 km\2\.      km\2\.               km\2\.
                                      Trestle.             days/shaft.
31d...........  3-4/DTH Cluster      Wall Shafts for Dry  22 78-inch shafts,           165  84,380.4 m/0.417417  37,909.7 m/0.417417  39,811 m/0.417417
                 Drill.               Dock 1 West.         10 hours/day, 7.5                 km\2\.               km\2\.               km\2\.
                                                           days/shaft.

[[Page 3170]]

 
32d...........  3-4/DTH Cluster      Foundation Shafts    23 108-inch shafts,          196  225,376.2 m/         101,255.2 m/         39,811 m/0.417417
                 Drill.               for Dry Dock 1       10 hours/day, 8.5                 0.417417 km\2\.      0.417417 km\2\.      km\2\.
                                      West.                days/pile.
33d...........  3-4/DTH Cluster      Dry Dock 1 West      18 78-inch shafts,           135  84,380.4 m/0.417417  37,909.7 m/0.417417  39,811 m/0.417417
                 Drill.               Leveling Piles       10 hours/day, 7.5                 km\2\.               km\2\.               km\2\.
                                      (Diving Board        days/pile.
                                      Shafts).
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Note, for the purposes of this analysis, the proposed construction years are identified as years 2 through 5; takes for marine mammals during Year 1
  of the Navy's construction activities were authorized in a previously issued IHA (87 FR 19886; April 6, 2022).
\2\ To determine underwater harassment zone size, ensonified areas from the source were clipped along the shoreline using Geographical Information
  Systems (GIS).


                            Table 8--Calculated Distance and Areas of Level A and Level B Harassment for Non-Impulsive Noise
                                                 [Rotary drilling and vibratory pile driving/extracting]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                     Level A harassment \2\           Level B harassment
                                                                                  Total    -------------------------------------------------------------
  Activity ID    Year \1\/ activity        Purpose          Duration, count,    production     High frequency
                                                           size, and or rate       days      cetaceans (harbor     Phocid pinnipeds       All species
                                                                                                 porpoise)
--------------------------------------------------------------------------------------------------------------------------------------------------------
R.............  2/Vibratory Pile     Dry Dock 1 North     48 28-inch Z-shaped            6  19.4 m/0.001041      8.0 m/0.0002 km\2\.  13,594 m/0.417417
                 Driving.             Entrance Temporary   sheets, 8 sheets/                 km\2\.                                    km\2\.
                                      Cofferdam.           day.
2.............  2-3/Vibratory        Remove Berth 1       168 25-inch Z-                42  12.2 m/0.000454      5.0 m/0.000078       13,594 m/0.417417
                 Extraction.          Sheet Piles.         shaped sheets, 4                  km\2\.               km\2\.               km\2\.
                                                           piles/day.
5.............  2/Vibratory Pile     Install Berth 1      28 28-inch Z-shaped            8  12.2 m/0.000454      5.0 m/0.000078       13,594 m/0.417417
                 Driving.             Support of           sheets, 4 piles/                  km\2\.               km\2\.               km\2\.
                                      Excavation.          day.
8.............  2/Vibratory Pile     Install Temporary    14 28-inch Z-shaped            4  12.2 m/0.000454      5.0 m/0.000078       13,594 m/0.417417
                 Driving.             Cofferdam            sheets, 4 piles/                  km\2\.               km\2\.               km\2\.
                                      Extension.           day.
12............  2/Vibratory Pile     Center Wall Tie-In   15 28-inch Z-shaped            4  12.2 m/0.000454      5.0 m/0.000078       13,594 m/0.417417
                 Driving.             to Existing West     sheets, 4 piles/                  km\2\.               km\2\.               km\2\.
                                      Closure Wall.        day.
18............  2/Vibratory          Berth 11 End Wall    60 28-inch Z-shaped           10  19.4 m/0.001041      8.0 m/0.0002 km\2\.  13,594 m/0.417417
                 Extraction.          Temporary Guide      sheets, 8 piles/                  km\2\.                                    km\2\.
                                      Wall.                day.
19............  2/Vibratory          Remove Berth 1       28 28-inch Z-shaped            5  19.4 m/0.001041      8.0 m/0.0002 km\2\.  13,594 m/0.417417
                 Extraction.          Support of           sheets, 8 piles/                  km\2\.                                    km\2\.
                                      Excavation.          day.
20............  2/Vibratory          Remove Berth 1       108 28-inch Z-                18  16.0 m/0.000733      6.6 m/0.000136       13,594 m/0.417417
                 Extraction.          Emergency Repairs.   shaped sheets, 6                  km\2\.               km\2\.               km\2\.
                                                           piles/day.
23............  2-3/Vibratory        Dry Dock 1 North-    16 28-inch Z-shaped            3  19.4 m/0.001041      8.0 m/0.0002 km\2\.  13,594 m/0.417417
                 Extraction.          Remove Center Wall   sheets, 8 piles/                  km\2\.                                    km\2\.
                                      Tie-in to West       day.
                                      Closure Wall.
24............  2-3/Vibratory Pile   Center Wall East     23 28-inch Z-shaped           12  7.7 m/0.000185       3.2 m/0.000032       13,594 m/0.417417
                 Driving.             Tie-in to Existing   sheets, 2 piles/                  km\2\.               km\2\.               km\2\.
                                      Wall.                day.
25............  2-3/Vibratory        Dry Dock 1 West      15 28-inch Z-shaped            3  19.4 m/0.001041      8.0 m/0.0002 km\2\.  13,594 m/0.417417
                 Extraction.          Remove Center Wall   sheets, 8 piles/                  km\2\.                                    km\2\.
                                      Tie-in to West       day.
                                      Closure Wall.
26............  2-3/Vibratory        Remove Center Wall   23 28-inch, Z-                12  19.4 m/0.001041      8.0 m/0.0002 km\2\.  13,594 m/0.417417
                 Extraction.          Tie-in to Existing   shaped sheets, 8                  km\2\.                                    km\2\.
                                      Wall.                piles/day.
27............  2-3/Vibratory        Remove Temporary     96 28-inch Z-shaped           12  19.4 m/0.001041      8.0 m/0.0002 km\2\.  13,594 m/0.417417
                 Extraction.          Cofferdam.           sheets, 8 piles/                  km\2\.                                    km\2\.
                                                           day.
28............  2-3/Vibratory        Remove Temporary     14 28-inch Z-shaped            2  19.4 m/0.001041      8.0 m/0.0002 km\2\.  13,594 m/0.417417
                 Extraction.          Cofferdam            sheets, 8 piles/                  km\2\.                                    km\2\.
                                      Extension.           day.
A1............  2/Rotary Drill.....  Dry Dock 1 North     18 102-inch                   18  2.1 m/0.000014       1.3 m/0.000005       1,848 m/0.417417
                                      Entrance             borings, 1 hour/                  km\2\.               km\2\.               km\2\.
                                      Foundation Support   day, 1 casing/day.
                                      Piles--Install
                                      Outer Casing.
A2............  2/Rotary Drill.....  Dry Dock 1 North     18 102-inch                   18  8.9 m/0.000248       5.4 m/0.000091       1,848 m/0.41747
                                      Entrance             borings, 9 hours/                 km\2\.               km\2\.               km\2\.
                                      Foundation Support   day, 1 socket/day.
                                      Piles--Pre-Drill
                                      Socket.

[[Page 3171]]

 
A3............  2/Rotary Drill.....  Dry Dock 1 North     18 102-inch                   18  0.8 m/0.000002       0.5 m/0.000001       1,848 m/0.417417
                                      Entrance             borings, 15                       km\2\.               km\2\.               km\2\.
                                      Foundation Support   minutes/casing, 1
                                      Piles--Remove        casing/day.
                                      Outer Casing.
9a............  2/Rotary Drill.....  Gantry Crane         16 102-inch                   16  2.1 m/0.000014       1.3 m/0.000005       1,848 m/0.417417
                                      Support--Install     borings, 1 hour/                  km\2\.               km\2\.               km\2\.
                                      Outer Casing.        day, 1 casing/day.
9b............  2/Rotary Drill.....  Gantry Crane         16 102-inch                   16  8.9 m/0.000248       5.4 m/0.000091       1,848 m/0.417417
                                      Support--Pre-Drill   borings, 9 hours/                 km\2\.               km\2\.               km\2\.
                                      Socket.              day, 1 socket/day.
9c............  2/Rotary Drill.....  Gantry Crane         16 102-inch                   16  0.8 m/0.000002       0.5 m/0.000001       1,848 m/0.417417
                                      Support--Remove      borings, 15                       km\2\.               km\2\.               km\2\.
                                      Outer Casing.        minutes/casing, 1
                                                           casing/day.
13a...........  2-3/Rotary Drill...  Dry Dock 1 North     20 102-inch                   20  2.1 m/0.000014       1.3 m/0.000005       1,848 m/0.417417
                                      Temporary Work       borings, 1 hour/                  km\2\.               km\2\.               km\2\.
                                      Trestle--Install     day, 1 casing/day.
                                      Outer Casing.
13b...........  2-3/Rotary Drill...  Dry Dock 1 North     20 102-inch                   20  8.9 m/0.000248       5.4 m/0.000091       1,848 m/0.417417
                                      Temporary Work       borings, 9 hours/                 km\2\.               km\2\.               km\2\.
                                      Trestle--Pre-Drill   day, 1 socket/day.
                                      Socket.
13c...........  2-3/Rotary Drill...  Dry Dock 1 North     20 102-inch                   20  0.8 m/0.000002       0.5 m/0.000001       1,848 m/0.417417
                                      Temporary Work       borings, 15                       km\2\.               km\2\.               km\2\.
                                      Trestle--Remove      minutes/casing, 1
                                      Outer Casing.        casing//day.
14............  2-3/Rotary Drill...  Remove Dry Dock 1    20 84-inch borings,           20  0.8 m/0.000002       0.5 m/0.000001       1,848 m/0.417417
                                      North Temporary      15 minutes/casing,                km\2\.               km\2\.               km\2\.
                                      Work Trestle Piles.  1 casing/day.
15a...........  2-3/Rotary Drill...  Dry Dock 1 North     18 84-inch borings,           18  2.1 m/0.000014       1.3 m/0.000005km\2\  1,848 m/0.417417
                                      Leveling Piles--     1 hour/day, 1                     km\2\.                                    km\2\.
                                      Install Outer        casing/day.
                                      Casing.
15b...........  2-3/Rotary Drill...  Dry Dock 1 North     18 84-inch borings,           18  8.9 m/0.000248       5.4 m/0.000091       1,848 m/0.417417
                                      Leveling Piles--     9 hours/day, 1                    km\2\.               km\2\.               km\2\.
                                      Pre-Drill Socket.    socket/day.
15c...........  2-3/Rotary Drill...  Dry Dock 1 North     18 84-inch borings,           18  0.8 m/0.000002       0.5 m/0.000001       1,848 m/0.417417
                                      Leveling Piles--     15 minutes/casing,                km\2\.               km\2\.               km\2\.
                                      Remove Outer         1 casing/day.
                                      Casing.
16a...........  2-3/Rotary Drill...  Dry Dock 1 North     20 102-inch                   20  2.1 m/0.000014       1.3 m/0.000005       1,848 m/0.417417
                                      Wall Shafts--        borings, 1 hour/                  km\2\.               km\2\.               km\2\.
                                      Install Outer        day, 1 casing/day.
                                      Casing.
16b...........  2-3/Rotary Drill...  Dry Dock 1 North     20 102-inch                   20  8.9 m/0.000248       5.4 m/0.000091       1,848 m/0.417417
                                      Wall Shafts--Pre-    borings, 9 hours/                 km\2\.               km\2\.               km\2\.
                                      Drill Socket.        day, 1 socket/day.
16c...........  2-3/Rotary Drill...  Dry Dock 1 North     20 102-inch                   20  0.8 m/0.000002       0.5 m/0.000001       1,848 m/0.417417
                                      Wall Shafts--        borings, 15                       km\2\.               km\2\.               km\2\.
                                      Remove Outer         minutes/casing, 1
                                      Casing.              casing/day.
17a...........  2-3/Rotary Drill...  Dry Dock 1 North     23 126-inch                   23  2.1 m/0.000014       1.3 m/0.000005       1,848 m/0.417417
                                      Foundation Shafts--  borings, 1 hour/                  km\2\.               km\2\.               km\2\.
                                      Install Outer        day, 1 casing/day.
                                      Casing.
17b...........  2-3/Rotary Drill...  Dry Dock 1 North     23 126-inch                   23  8.9 m/0.000248       5.4 m/0.000091       1,848 m/0.417417
                                      Foundation Shafts    borings, 9 hours/                 km\2\.               km\2\.               km\2\.
                                      Pre-Drill Sockets.   day, 1 socket/day.
17c...........  2-3/Rotary Drill...  Dry Dock 1 North     23 126-inch                   23  0.8 m/0.000002       0.5 m/0.000001       1,848 m/0.417417
                                      Foundation Shafts--  borings, 15                       km\2\.               km\2\.               km\2\.
                                      Remove Outer         minutes/casing, 1
                                      Casing.              casing/day.
29a...........  3-4/Rotary Drill...  Dry Dock 1 West      20 102-inch                   20  2.1 m/0.000014       1.3 m/0.000005       1,848 m/0.417417
                                      Temporary Work       borings, 1 hour/                  km\2\.               km\2\.               km\2\.
                                      Trestle--Install     day, 1 casing/day.
                                      Outer Casing.
29b...........  3-4/Rotary Drill...  Dry Dock 1 West      20 102-inch                   20  8.9 m/0.000248       5.4 m/0.000091       1,848 m/0.417417
                                      Temporary Work       borings, 9 hours/                 km\2\.               km\2\.               km\2\.
                                      Trestle--Pre-Drill   day, 1 socket/day.
                                      Socket.
29c...........  3-4/Rotary Drill...  Dry Dock 1 West      20 102-inch                   20  0.8 m/0.000002       0.5 m/0.000001       1,848 m/0.417417
                                      Temporary Work       borings, 15                       km\2\.               km\2\.               km\2\.
                                      Trestle--Remove      minutes/casing, 1
                                      Outer Casing.        casing/day.
30............  3-4/Rotary Drill...  Dry Dock 1 West      20 84-inch borings,           20  0.8 m/0.000002       0.5 m/0.000001       1,848 m/0.417417
                                      Remove Temporary     15 minutes/pile, 1                km\2\.               km\2\.               km\2\.
                                      Work Trestle Piles.  pile/day.
31a...........  3-4/Rotary Drill...  Dry Dock 1 West      22 102-inch                   22  2.1 m/0.000014       1.3 m/0.000005       1,848 m/0.417417
                                      Wall Shafts--        borings, 1 hour/                  km\2\.               km\2\.               km\2\.
                                      Install Outer        day, 1 casing/day.
                                      Casing.

[[Page 3172]]

 
31b...........  3-4/Rotary Drill...  Dry Dock 1 West      22 102-inch                   22  8.9 m/0.000248       5.4 m/0.000091       1,848 m/0.417417
                                      Wall Shafts--Pre-    borings, 9 hours/                 km\2\.               km\2\.               km\2\.
                                      Drill Socket.        day, 1 socket/day.
31c...........  3-4/Rotary Drill...  Dry Dock 1 West      22 102-inch                   22  0.8 m/0.000002       0.5 m/0.000001       1,848 m/0.417417
                                      Wall Shafts--        borings, 15                       km\2\.               km\2\.               km\2\.
                                      Remove Outer         minutes/casing, 1
                                      Casing.              casing/day.
32a...........  3-4/Rotary Drill...  Dry Dock 1 West      23 126-inch                   23  2.1 m/0.000014       1.3 m/0.000005       1,848 m/0.417417
                                      Foundation Shafts--  borings, 1 hour/                  km\2\.               km\2\.               km\2\.
                                      Install Outer        day, 1 casing/day.
                                      Casing.
32b...........  3-4/Rotary Drill...  Dry Dock 1 West      23 126-inch                   23  8.9 m/0.000248       5.4 m/0.000091       1,848 m/0.417417
                                      Foundation Shafts    borings, 9 hours/                 km\2\.               km\2\.               km\2\.
                                      Pre-Drill Sockets.   day, 1 socket/day.
32c...........  3-4/Rotary Drill...  Dry Dock 1 West      23 126-inch                   23  0.8 m/0.000002       0.5 m/0.000001       1,848 m/0.417417
                                      Foundation Shafts--  borings, 15                       km\2\.               km\2\.               km\2\.
                                      Remove Outer         minutes/casing, 1
                                      Casing.              casing/day.
33a...........  3-4/Rotary Drill...  Dry Dock 1 North     18 84-inch borings,           18  2.1 m/0.000014       1.3 m/0.000005       1,848 m/0.417417
                                      Leveling Piles--     1 hour/day, 1                     km\2\.               km\2\.               km\2\.
                                      Install Outer        casing/day.
                                      Casing.
33b...........  3-4/Rotary Drill...  Dry Dock 1 West,     18 84-inch borings,           18  8.9 m/0.000248       5.4 m/0.000091       1,848 m/0.417417
                                      Leveling Piles--     9 hours/day, 1                    km\2\.               km\2\.               km\2\.
                                      Pre-Drill Socket.    socket/day.
33c...........  3-4/Rotary Drill...  Dry Dock 1 North     18 84-inch borings,           18  0.8 m/0.000002       0.5 m/0.000001       1,848 m/0.417417
                                      Leveling Piles--     15 minutes/casing,                km\2\.               km\2\.               km\2\.
                                      Remove Outer         1 casing/day.
                                      Casing.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Note, for the purposes of this analysis, the proposed construction years are identified as years 2 through 5; takes for marine mammals during Year 1
  of the Navy's construction activities were authorized in a previously issued IHA (87 FR 19886; April 6, 2022).
\2\ To determine underwater harassment zone size, ensonified areas from the source were clipped along the shoreline using Geographical Information
  Systems (GIS).

    The calculated maximum distances corresponding to the underwater 
marine mammal harassment zones from impulsive (impact pile driving, 
rock hammering, DTH) and non-impulsive (vibratory pile driving, rotary 
drilling) noise and the area of the harassment zone within the region 
of influence (ROI) are summarized in Tables 7 and 8, respectively. 
Sound source locations were chosen to model the greatest possible 
affected areas; typically, these locations would be at the riverward 
end of the super flood basin. The calculated distances do not take the 
land masses into consideration, but the ensonified areas do. Neither 
consider the reduction that would be achieved by the required use of a 
bubble curtain and therefore all take estimates are considered 
conservative. Refer to Figures 6-1 through 6-20 of the Navy's 
application for visual representations of the calculated maximum 
distances corresponding to the underwater marine mammal harassment 
zones from impulsive (impact pile driving, rock hammering, DTH) and 
non-impulsive (vibratory pile driving, rotary drilling) noise and the 
corresponding area of the harassment zone within the ROI.
    Calculated distances to Level A harassment and Level B harassment 
thresholds are large, especially for DTH and rock hammering activities. 
However, in most cases 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 harassment isopleths. Refer to Figure 1-3 in the Navy's 
application for the ROI, which illustrates that the land masses 
preclude the sound from traveling more than approximately 870 m (3,000 
ft) from the source, at most. Areas encompassed within the threshold 
(harassment zones) were calculated by using a Geographical Information 
System (GIS) to clip the maximum calculated distances to the extent of 
the ROI (see Figure 2).
    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 (PTS Onset) harassment 
thresholds (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 substantial amount of rock hammering and DTH excavation 
required for the construction of the multifunctional expansion of Dry 
Dock 1, the only scenarios identified in which cluster drills and/or 
rock hammers would not be in operation would be at the end of the 
project (construction years 3 and 4) when two rotary drills or two 
rotary drills and a DTH mono-hammer (9-inch) could be used 
simultaneously (refer to Table 2).
    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 (NMFS, 2021d; WSDOT, 2020).

[[Page 3173]]



         Table 9--Adjustments for Sound Exposure Level Criterion
------------------------------------------------------------------------
                                                       Adjustments to
                                  Difference in      specifications for
         Source types            sound level  (at    Level A harassment
                                specified meters)       RMS/SELss *
                                                        calculations
------------------------------------------------------------------------
Non-impulsive, continuous/Non-  0 or 1 dB........  Add 3 dB to the
 impulsive, continuous, OR.                         highest sound level
                                                    (at specified
                                                    meters) AND adjust
                                                    number of piles per
                                                    day to account for
                                                    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).
Impulsive source (multiple      4 to 9 dB........  Add 1 dB to the
 strikes per second)/Impulsive  10 dB or more....   highest sound level
 source (multiple strikes per                       (at specified
 second).                                           meters) AND adjust
                                                    number of piles per
                                                    day to account for
                                                    overlap (space and
                                                    time).
                                                   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 SLs are identified. Of 
the three highest SLs, 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, 2021d). By 
using this method, revised proxy SPLs were determined for the use of 
two 102-inch diameter rotary drills and the use of two 108-inch rotary 
drills and one 9-inch DTH mono-hammer. The revised proxy values are 
presented in Table 10 and the resulting harassment zones are summarized 
in Table 11 (visually depicted in Figures 6-21 and 6-22 in the Navy's 
application).

                  Table 10--Revised Proxy Values for Simultaneous Use of Non-Impulsive Sources
----------------------------------------------------------------------------------------------------------------
                       Source A                                         Source B
-------------------------------------------------------------------------------------------------  Revised proxy
                                         RMS SPL  (dB                              RMS SPL  (dB    RMS SPL  (dB
               Equipment                     re 1               Equipment              re 1            re 1
                                          [micro]Pa)                                [micro]Pa)      [micro]Pa)
----------------------------------------------------------------------------------------------------------------
Rotary Drill..........................             154  Rotary Drill............             154             157
Two Rotary Drills.....................             157  DTH Mono-Hammer.........             167             167
----------------------------------------------------------------------------------------------------------------


               Table 11--Level A and Level B Harassment Zones Resulting From Concurrent Activities
----------------------------------------------------------------------------------------------------------------
                                                      Level A harassment                    Level B harassment
                                      --------------------------------------------------------------------------
       Multiple source scenario             High frequency
                                          cetaceans  (harbor        Phocid pinnipeds           All species
                                              porpoise)
----------------------------------------------------------------------------------------------------------------
2 Rotary Drills (9 hrs)..............  23.6 m/0.001514 km\2\..  9.7 m/0.000294 km\2\...  2,929 m/0.417417 km\2\.
2 Rotary Drills (9 hrs) and 1 DTH      74.2 m/0.012773 km\2\..  30.5 m/0.002489 km\2\..  13,594 m/0.417417
 Mono-Hammer (5 hrs).                                                                     km\2\.
----------------------------------------------------------------------------------------------------------------

Marine Mammal Occurrence and Take Estimation

    In this section we provide information about the occurrence of 
marine mammals, including density or other relevant information, that 
will inform the take calculations. We also describe how the information 
provided above is synthesized to produce a quantitative estimate of the 
take that is reasonably likely to occur and proposed for authorization.
    Potential exposures to impact 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. A 10 m shutdown zone designed 
to prevent animal interactions with equipment was subtracted from the 
Level A harassment zone, and the area of the Level A harassment zone 
was subtracted from the Level B harassment zone to avoid double 
counting of takes during these take calculations. Days of construction 
were conservatively based on relatively slow daily production rates. 
The pile type, size, and installation method that produce the largest 
zone of influence were used to estimate exposure of marine mammals to 
noise impacts. In instances where an activity would ensonify the entire 
ROI to the Level A harassment threshold, all potential takes are 
assumed to be by Level A harassment.
    Because some construction activities would occur over more than one 
construction year, the number of takes per year were determined by the 
percent

[[Page 3174]]

duration of each construction activity occurring each year (calculated 
by months). For example, if an activity were to occur for 6 months, 
with 3 months occurring in year 2 and 3 months occurring in year 3, 
then 50 percent of the takes were assigned to year 2 and 50 percent to 
year 3. In instances where only 1 take was calculated but activities 
spanned more than one construction year, one take was requested for 
each construction year. Table 12 summarizes the calculated duration 
percentages for each activity that were used to divide take numbers by 
year.

                                                    Table 12--Division of Takes by Construction Year
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                          Total amount and estimated                                   Year 2 \1\   Year 3 \1\   Year 4 \1\   Year 5 \1\
              Activity ID                           dates                    Activity component         % takes      % takes      % takes      % takes
--------------------------------------------------------------------------------------------------------------------------------------------------------
(A1,2,3,4) Center Wall--Install         Drill 18 shafts, Apr 23 to     Install 102-inch diameter              100            0            0            0
 Foundation Support Piles.               Aug 23.                        outer casing.
                                                                       Pre-drill 102-inch outer               100            0            0            0
                                                                        casing.
                                                                       Remove 102-inch outer casing.          100            0            0            0
                                                                       Drill 79-inch diameter shaft.          100            0            0            0
(R) Dry Dock 1 North Entrance--Install  Install 48 sheet piles, Apr    28-inch wide Z-shaped sheets.          100            0            0            0
 Temporary Cofferdam.                    23 to May 23.
(1) Berth 11--Remove Shutter Panels...  Remove 112 panels, Apr 23 to   Concrete shutter panels......          100            0            0            0
                                         Apr 23.
(2) Berth 1--Remove Sheet Piles.......  Remove 168 sheet piles, Apr    25-inch-wide Z-shaped........           80           20            0            0
                                         23 to Jun 24.
(3) Berth 1--Remove Granite Block Quay  2,800 cy, Apr 23 to Jun 24...  Removal of granite blocks....           80           20            0            0
 Wall.
(4) Berth 1--Top of Wall Removal for    320 lf, Apr 23 to Jun 24.....  Mechanical concrete removal..           80           20            0            0
 Waler Installation.
(5) Berth 1--Install southeast corner   Install 28 sheet piles, Apr    28-inch-wide Z-shaped........          100            0            0            0
 SOE.                                    23 to Jul 23.
(6) Berth 11--Mechanical Rock Removal   700 cy, Apr 23 to Aug 23.....  Excavate Bedrock.............          100            0            0            0
 at Basin Floor.
(7) Berth 11 Face--Mechanical Rock      Drill 924 relief holes, Apr    4-6 inch diameter holes......          100            0            0            0
 Removal at Basin Floor.                 23 to Aug 23.
(8) Temporary Cofferdam Extension.....  Install 14 sheet piles, Apr    28-inch-wide Z-shaped........          100            0            0            0
                                         23 to Jun 23.
(9a, b, c, d) Gantry crane Support      Drill 16 shafts, Apr 23 to     Set 102-inch diameter casing.          100            0            0            0
 Piles at Berth 1 West.                  Aug 23.                       Pre-drill 102-inch rock                100            0            0            0
                                                                        socket.
                                                                       Remove 102-inch casing.......          100            0            0            0
                                                                       72-inch diameter shafts......          100            0            0            0
(10) Berth 1--Mechanical Rock Removal   500 cy, Apr 23 to Sep 23.....  Excavate Bedrock.............          100            0            0            0
 at Basin Floor.
(11) Dry Dock 1 North Entrance--Drill   Drill 50 rock anchors, Apr 23  9-inch diameter holes........          100            0            0            0
 Tremie Tie Downs.                       to Oct 23.
(12) Center Wall--Install Tie-In to     Install 15 sheet piles, Apr    28-inch wide Z-shaped........          100            0            0            0
 Existing West Closure Wall.             23 to Dec 23.
(13a, b, c, d) Dry Dock 1 North--       Drill 20 shafts, May 23 to     Set 102-inch diameter casing.           60           40            0            0
 Temporary Piles.                        Nov 24.                       Pre-drill 102-inch rock                 60           40            0            0
                                                                        socket.
                                                                       Remove 102-inch casing.......           60           40            0            0
                                                                       84-inch diameter shafts......           60           40            0            0
(14) Dry Dock 1 North--Remove           Remove 20 piles, May 23 to     84-inch diameter drill piles.           60           40            0            0
 Temporary Work Trestle Piles.           Nov 24.
(15a, b, c, d) Dry Dock 1 North--       Drill 18 shafts, May 23-Nov    Set 84-inch casing...........           60           40            0            0
 Install Leveling Piles (Diving Board    24.                           Pre-drill 84-inch rock socket           60           40            0            0
 Shafts).                                                              Remove 84-inch casing........           60           40            0            0
                                                                       78-inch diameter shaft.......           60           40            0            0
(16a, b, c, d) Wall Shafts for Dry      Drill 20 shafts, Jun 23 to     Set 102-inch diameter casing.           60           40            0            0
 Dock 1 North.                           Nov 24.                       Pre-drill 102-inch rock                 60           40            0            0
                                                                        socket.
                                                                       Remove 102-inch casing.......           60           40            0            0
                                                                       Drill 78-inch diameter shaft.           60           40            0            0
(17a, b, c, d) Foundation Shafts for    Drill 23 shafts, Jun 23 to     Set 126-inch diameter Casing.           60           40            0            0
 Dry Dock 1 North.                       Nov 24.                       Pre-drill 126-inch rock                 60           40            0            0
                                                                        socket.
                                                                       Remove 126-inch casing.......           60           40            0            0
                                                                       Drill 108-inch diameter                 60           40            0            0
                                                                        shafts.
(18) Berth 11 End Wall--Remove          Remove 60 sheet piles, Jul 23  28-inch wide Z-shaped........          100            0            0            0
 Temporary Guide Wall.                   to Aug 23.
(19) Remove Berth 1 southeast corner    Remove 28 sheet piles, Jul 23  28-inch-wide Z-shaped........          100            0            0            0
 SOE.                                    to Sep 23.
(20) Removal of Berth 1 Emergency       Remove 216 sheet piles, Aug    28-inch-wide Z-shaped........          100            0            0            0
 Repair Sheet Piles.                     23 to Mar 24.
(21) Removal of Berth 1 Emergency       765 cubic meters (1,000 cy),   Mechanical concrete removal..          100            0            0            0
 Repair Tremie Concrete.                 Aug 23 to Mar 24.
(22) Center wall foundation--Drill in   Install 72 rock anchors, Aug   9-inch diameter holes........           80           20            0            0
 monolith Tie Downs.                     23 to May 24.
(23) Center Wall--Remove tie-in to      Remove 16 sheet piles, Aug 23  28-inch-wide Z-shaped........           60           40            0            0
 existing west closure wall (Dry Dock    to Aug 24.
 1 North).
(24) Center wall East--sheet pile tie-  Install 23 sheet piles, Aug    28-inch wide Z-shaped........           50           50            0            0
 in to Existing Wall.                    23 to Oct 24.
(25) Remove tie-in to West Closure      Remove 15 sheet pile, Dec 23   28-inch wide Z-shaped........           30           70            0            0
 Wall (Dry Dock 1 West).                 to Dec 24.

[[Page 3175]]

 
(26) Remove Center wall East--sheet     Remove 23 sheet piles, Dec 23  28-inch wide Z-shaped........           30           70            0            0
 pile tie-in to Existing Wall (Dry       to Dec 24.
 Dock 1 West).
(27) Dry Dock 1 north entrance--Remove  Remove 96 sheet piles, Jan 24  28-inch wide Z-shaped........           33           66            0            0
 Temporary Cofferdam.                    to Sep 24.
(28) Remove Temporary Cofferdam         Remove 14 sheet piles, Jan 24  28-inch wide Z-shaped........           33           66            0            0
 Extension.                              to Sep 24.
(29a, b, c, d) Dry Dock 1 West--        Drill 20 shafts, Apr 24 to     Set 102-inch diameter casing.            0           50           50            0
 Install Temporary Piles.                Feb 26.                       Pre-drill 102-inch rock                  0           50           50            0
                                                                        socket.
                                                                       Remove 102-inch casing.......            0           50           50            0
                                                                       84-inch diameter shafts......            0           50           50            0
(30) Dry Dock 1 West--Remove Temporary  Remove 20 piles, Apr 24 to     84-inch diameter piles.......            0           50           50            0
 Work Trestle Piles.                     Feb 26.
(31a, b, c, d) Wall Shafts for Dry      Drill 22 shafts, Jun 24 to     Set 102-inch diameter casing.            0           50           50            0
 Dock 1 West.                            Feb 26.                       Pre-drill 102-inch rock                  0           50           50            0
                                                                        socket.
                                                                       Remove 102-inch casing.......            0           50           50            0
                                                                       78-inch diameter shaft.......            0           50           50            0
(32a, b, c, d) Foundation Shafts for    Drill 23 shafts, Jun 24 to     Set 126-inch casing..........            0           50           50            0
 Dry Dock 1 West.                        Feb 26.                       Pre-drill 126-inch rock                  0           50           50            0
                                                                        socket.                                 0           50           50            0
                                                                       Remove 126-inch casing.......            0           50           50            0
                                                                       Drill 108-inch diameter shaft
(33a, b, c, d) Dry Dock 1 West--        Drill 18 shafts, Jun 24 to     Set 84-inch casing...........            0           50           50            0
 Install Leveling Piles (Diving Board    Feb 26.                       Pre-drill 84-inch rock socket            0           50           50            0
 Shafts).                                                              Remove 84-inch casing........            0           50           50            0
                                                                       Drill 78-inch diameter shaft.            0           50           50            0
(34) Dry Dock 1 North--Tie Downs......  Install 36 rock anchors, Jul   9-inch diameter holes........            0           70           30            0
                                         24 to Jul 25.
(35) Dry Dock 1 West--Install Tie       Install 36 rock anchors, Dec   9-inch diameter hole.........            0            0           30           70
 Downs.                                  25 to Dec 26.
--------------------------------------------------------------------------------------------------------------------------------------------------------
* Note, for the purposes of this analysis, the proposed construction years are identified as years 2 through 5; takes for marine mammals during Year 1
  of the Navy's construction activities were authorized in a previously issued IHA (87 FR 19886; April 6, 2022).

    We describe how the information provided above is brought together 
to produce a quantitative take estimate in the species sections below. 
A summary of take proposed for authorization is available in Table 16.

Harbor Porpoise

    Harbor porpoises are expected to be present in the proposed project 
area from April to December. Based on density data from the NMSDD, 
their presence is highest in spring, decreases in summer, and slightly 
increases in fall. During construction monitoring in the project area, 
there were three harbor porpoise observations between April and 
December of 2017; two harbor porpoise observations in early August of 
2018; and one harbor porpoise observation in 2020 (Cianbro, 2018; Navy, 
2019; NAVFAC, 2021). There were no harbor porpoise observations in the 
project area in 2021 (NAVFAC, 2022). Given that monitoring data 
specific to the project area are available, the more general NMSDD data 
were not used to determine species density in the project area. 
Instead, the Navy used observation data from the 2017 and 2018 
construction monitoring for the Berth 11 Waterfront Improvements 
Project and determined that the density of harbor porpoise for the 
largest harassment zone was equal to 0.04/km\2\. Estimated take was 
calculated with this density estimate multiplied by the harassment zone 
multiplied by the days for each activity (see Table 13).

[[Page 3176]]



                                                                 Table 13--Estimated Take of Harbor Porpoise by Project Activity
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                Level A        Proposed take by Level A harassment        Level B        Proposed take by Level B harassment
                                                                     Total     harassment ---------------------------------------------  harassment --------------------------------------------
Activity  ID     Year/activity           Purpose        Density   production      zone                                                      zone
                                                                     days       (km\2\)     Total    Year 2   Year 3   Year 4   Year 5    (km\2\)     Total    Year 2   Year 3   Year 4   Year 5
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
A...........  2 Rotary Drill.....  Center Wall--            0.04          18     0.000014        0        0        0        0        0     0.417417        0        0        0        0        0
                                    Install
                                    Foundation
                                    Support Piles.
              2 Rotary Drill.....  Center Wall--            0.04          18     0.000248        0        0        0        0        0     0.417417        0        0        0        0        0
                                    Install
                                    Foundation
                                    Support Piles.
              2 Rotary Drill.....  Center Wall--            0.04          18     0.000002        0        0        0        0        0     0.417417        0        0        0        0        0
                                    Install
                                    Foundation
                                    Support Piles.
              2 DTH Cluster Drill  Center Wall--            0.04         117     0.417417        2        2        0        0        0     0.417417        0        0        0        0        0
                                    Install
                                    Foundation
                                    Support Piles.
R...........  2 Vibratory Pile     Dry Dock 1 North         0.04           6    0.0014041        0        0        0        0        0     0.417417        0        0        0        0        0
               Driving.             Entrance--Install
                                    Temporary
                                    Cofferdam.
              2 Impact Pile        Dry Dock 1 North         0.04           6     0.417417        0        0        0        0        0     0.417417        0        0        0        0        0
               Driving.             Entrance--Install
                                    Temporary
                                    Cofferdam.
1...........  2 Hydraulic Rock     Shutter Panel            0.04          56     0.417417        1        1        0        0        0     0.277858        0        0        0        0        0
               Hammer.              Demolition (112
                                    panels).
2...........  2-3 Vibratory        Remove Berth 1           0.04          42     0.000454        0        0        0        0        0     0.417417    \1\ 2        1        1        0        0
               Extraction.          Sheet Piles.
3...........  2-3 Hydraulic Rock   Removal of Granite       0.04          47     0.417417    \1\ 2        1        1        0        0     0.277858        0        0        0        0        0
               Hammer.              Quay Wall (2,800
                                    cy).
4...........  2-3 Hydraulic Rock   Berth 1 Top of           0.04          74     0.417417    \1\ 2        1        1        0        0     0.277858        0        0        0        0        0
               Hammer.              Wall Demolition
                                    for Waler Install
                                    (320 lf).
5...........  2 Vibratory Pile     Install Berth 1          0.04           8     0.000454        0        0        0        0        0     0.417417        0        0        0        0        0
               Driving.             Support of
                                    Excavation.
              2 Impact Pile        Berth 1 Support of       0.04           8     0.403411        0        0        0        0        0     0.417417        0        0        0        0        0
               Driving.             Excavation.
6...........  2 Hydraulic Rock     Mechanical Rock          0.04          60     0.417417        1        1        0        0        0     0.277858        0        0        0        0        0
               Hammer.              Removal (700 cy)
                                    at Berth 11 Basin
                                    Floor.
7...........  2 DTH Mono- hammer.  Relief Holes at          0.04          35     0.047675        0        0        0        0        0     0.417417        1        1        0        0        0
                                    Berth 11 Basin
                                    Floor.
8...........  2 Vibratory Pile     Install Temporary        0.04           4     0.000454        0        0        0        0        0     0.417417        0        0        0        0        0
               Driving.             Cofferdam
                                    Extension.
              2 Impact Pile        Temporary                0.04           4     0.403411        0        0        0        0        0     0.417417        0        0        0        0        0
               Driving.             Cofferdam
                                    Extension.
9...........  2 Rotary Drill.....  Gantry Crane             0.04          16     0.000014        0        0        0        0        0     0.417417        0        0        0        0        0
                                    Support--Install
                                    Outer Casing.
              2 Rotary Drill.....  Gantry Crane             0.04          16     0.000248        0        0        0        0        0     0.417417        0        0        0        0        0
                                    Support--Pre-
                                    Drill Socket.
              2 Rotary Drill.....  Gantry Crane             0.04          16     0.000002        0        0        0        0        0     0.417417        0        0        0        0        0
                                    Support--Remove
                                    Outer Casing.
              2 DTH Cluster Drill  Gantry Crane             0.04          80     0.417417        1        1        0        0        0     0.417417        0        0        0        0        0
                                    Support Piles.
10..........  2 Hydraulic Rock     Mechanical Rock          0.04          25     0.417417        0        0        0        0        0     0.277858        0        0        0        0        0
               Hammer.              Removal (300 cy)
                                    at Berth 1 Basin
                                    Floor.
11..........  2 DTH Mono-hammer..  Dry Dock 1 North         0.04          25     0.073751        0        0        0        0        0     0.417417        0        0        0        0        0
                                    Entrance Rock
                                    Anchors.
12..........  2 Vibratory Pile     Center Wall Tie-In       0.04           4     0.000454        0        0        0        0        0     0.417417        0        0        0        0        0
               Driving.             to Existing West
                                    Closure Wall.
              2 Impact Pile        Center Wall Tie-in       0.04           4     0.403411        0        0        0        0        0     0.417417        0        0        0        0        0
               Driving.             to West Closure
                                    Wall.
13..........  2-3 Rotary Drill...  Dry Dock 1 North         0.04          20     0.000014        0        0        0        0        0     0.417417        0        0        0        0        0
                                    Temporary Work
                                    Trestle--Install
                                    Outer Casing.
              2-3 Rotary Drill...  Dry Dock 1 North         0.04          20     0.000248        0        0        0        0        0     0.417417        0        0        0        0        0
                                    Temporary Work
                                    Trestle--Pre-
                                    Drill Socket.
              2-3 Rotary Drill...  Dry Dock 1 North         0.04          20     0.000002        0        0        0        0        0     0.417417        0        0        0        0        0
                                    Temporary Work
                                    Trestle--Remove
                                    Outer Casing.
              2-3 DTH Cluster      Dry Dock 1 North         0.04          70     0.417417    \1\ 2        1        1        0        0     0.417417        0        0        0        0        0
               Drill.               Temporary Work
                                    Trestle.

[[Page 3177]]

 
14..........  2-3 Rotary Drill...  Remove Dry Dock 1        0.04          20     0.000002        0        0        0        0        0     0.417417        0        0        0        0        0
                                    North Temporary
                                    Work Trestle
                                    Piles.
15..........  2-3 Rotary Drill...  Dry Dock 1 North         0.04          18     0.000014        0        0        0        0        0     0.417417        0        0        0        0        0
                                    Leveling Piles--
                                    Install Outer
                                    Casing.
              2-3 Rotary Drill...  Dry Dock 1 North         0.04          18     0.000248        0        0        0        0        0     0.417417        0        0        0        0        0
                                    Leveling Piles--
                                    Pre-Drill Socket.
              2-3 Rotary Drill...  Dry Dock 1 North         0.04          18     0.000002        0        0        0        0        0     0.417417        0        0        0        0        0
                                    Leveling Piles--
                                    Remove Outer
                                    Casing.
              2-3 DTH Cluster      Dry Dock 1 North         0.04         135     0.417417        2        1        1        0        0     0.417417        0        0        0        0        0
               Drill.               Leveling Piles
                                    (Diving Board
                                    Shafts).
16..........  2-3 Rotary Drill...  Dry Dock 1 North         0.04          20     0.000014        0        0        0        0        0     0.417417        0        0        0        0        0
                                    Wall Shafts--
                                    Install Outer
                                    Casing.
              2-3 Rotary Drill...  Dry Dock 1 North         0.04          20     0.000248        0        0        0        0        0     0.417417        0        0        0        0        0
                                    Wall Shafts - Pre-
                                    Drill Socket.
              2-3 Rotary Drill...  Dry Dock 1 North         0.04          20     0.000002        0        0        0        0        0     0.417417        0        0        0        0        0
                                    Wall Shafts--
                                    Remove Outer
                                    Casing.
              2-3 DTH Cluster      Wall Shafts for          0.04         150     0.417417        3        2        1        0        0     0.417417        0        0        0        0        0
               Drill.               Dry Dock 1 North.
17..........  2-3 Rotary Drill...  Dry Dock 1 North         0.04          23     0.000014        0        0        0        0        0     0.417417        0        0        0        0        0
                                    Foundation
                                    Shafts--Install
                                    Outer Casing.
              2-3 Rotary Drill...  Dry Dock 1 North         0.04          23     0.000248        0        0        0        0        0     0.417417        0        0        0        0        0
                                    Foundation Shafts
                                    Pre-Drill Sockets.
              2-3 Rotary Drill...  Dry Dock 1 North         0.04          23     0.000002        0        0        0        0        0     0.417417        0        0        0        0        0
                                    Foundation
                                    Shafts--Remove
                                    Outer Casing.
              2-3 DTH Cluster      Foundation Shafts        0.04         196     0.417417        3        2        1        0        0     0.417417        0        0        0        0        0
               Drill.               for Dry Dock 1
                                    North.
18..........  2 Vibratory          Berth 11 End Wall        0.04          10     0.001041        0        0        0        0        0     0.417417        0        0        0        0        0
               Extraction.          Temporary Guide
                                    Wall.
19..........  2 Vibratory          Remove Berth 1           0.04           5     0.001041        0        0        0        0        0     0.417417        0        0        0        0        0
               Extraction.          Support of
                                    Excavation.
20..........  2 Vibratory          Remove Berth 1           0.04          18     0.000733        0        0        0        0        0     0.417417        1        1        0        0        0
               Extraction.          Emergency Repairs.
21..........  2 Hydraulic Rock     Removal of               0.04          15     0.417417        0        0        0        0        0     0.277858        0        0        0        0        0
               Hammer.              Emergency Repair
                                    Concrete (500 cy)
                                    at Berth 1.
22..........  2-3 DTH Mono-hammer  Center Wall              0.04          36     0.073751        0        0        0        0        0     0.417417        0        0        0        0        0
                                    Foundation Rock
                                    Anchors.
23..........  2-3 Vibratory        Dry Dock 1 North-        0.04           3     0.001041        0        0        0        0        0     0.417417        0        0        0        0        0
               Extraction.          Remove Center
                                    Wall Tie-in to
                                    West Closure Wall.
24..........  2-3 Vibratory Pile   Center Wall East         0.04          12     0.000185        0        0        0        0        0     0.417417        0        0        0        0        0
               Driving.             Tie-in to
                                    Existing Wall.
              2-3 Impact Pile      Center Wall East         0.04          12     0.334747        0        0        0        0        0     0.417417        0        0        0        0        0
               Driving.             Tie-in to
                                    Existing Wall.
25..........  2-3 Vibratory        Dry Dock 1 West          0.04           3     0.001041        0        0        0        0        0     0.417417        0        0        0        0        0
               Extraction.          Remove Center
                                    Wall Tie-in to
                                    West Closure Wall.
26..........  2-3 Vibratory        Remove Center Wall       0.04          12     0.001041        0        0        0        0        0     0.417417        0        0        0        0        0
               Extraction.          Tie-in to
                                    Existing Wall.
27..........  2-3 Vibratory        Remove Temporary         0.04          12     0.001041        0        0        0        0        0     0.417417        0        0        0        0        0
               Extraction.          Cofferdam.
28..........  2-3 Vibratory        Remove Temporary         0.04           2     0.001041        0        0        0        0        0     0.417417        0        0        0        0        0
               Extraction.          Cofferdam
                                    Extension.
29..........  3-4 Rotary Drill...  Dry Dock 1 West          0.04          20     0.000014        0        0        0        0        0     0.417417        0        0        0        0        0
                                    Temporary Work
                                    Trestle--Install
                                    Outer Casing.
              3-4 Rotary Drill...  Dry Dock 1 West          0.04          20     0.000248        0        0        0        0        0     0.417417        0        0        0        0        0
                                    Temporary Work
                                    Trestle--Pre-
                                    Drill Socket.
              3-4 Rotary Drill...  Dry Dock 1 West          0.04          20     0.000002        0        0        0        0        0     0.417417        0        0        0        0        0
                                    Temporary Work
                                    Trestle--Remove
                                    Outer Casing.
              3-4 DTH Cluster      Dry Dock 1 West          0.04          70     0.417417    \1\ 2        0        1        1        0     0.417417        0        0        0        0        0
               Drill.               Temporary Work
                                    Trestle.
30..........  3-4 Rotary Drill...  Dry Dock 1 West          0.04          20     0.000002        0        0        0        0        0     0.417417        0        0        0        0        0
                                    Remove Temporary
                                    Work Trestle
                                    Piles.
31..........  3-4 Rotary Drill...  Dry Dock 1 West          0.04          22     0.000014        0        0        0        0        0     0.417417        0        0        0        0        0
                                    Wall Shafts--
                                    Install Outer
                                    Casing.

[[Page 3178]]

 
              3-4 Rotary Drill...  Dry Dock 1 West          0.04          22     0.000248        0        0        0        0        0     0.417417        0        0        0        0        0
                                    Wall Shafts--Pre-
                                    Drill Socket.
              3-4 Rotary Drill...  Dry Dock 1 West          0.04          22     0.000002        0        0        0        0        0     0.417417        0        0        0        0        0
                                    Wall Shafts--
                                    Remove Outer
                                    Casing.
              3-4 DTH Cluster      Wall Shafts for          0.04         165     0.417417        3        0        1        2        0     0.417417        0        0        0        0        0
               Drill.               Dry Dock 1 West.
32..........  3-4 Rotary Drill...  Dry Dock 1 West          0.04          23     0.000014        0        0        0        0        0     0.417417        0        0        0        0        0
                                    Foundation
                                    Shafts--Install
                                    Outer Casing.
              3-4 Rotary Drill...  Dry Dock 1 West          0.04          23     0.000248        0        0        0        0        0     0.417417        0        0        0        0        0
                                    Foundation Shafts
                                    Pre-Drill Sockets.
              3-4 Rotary Drill...  Dry Dock 1 West          0.04          23     0.000002        0        0        0        0        0     0.417417        0        0        0        0        0
                                    Foundation
                                    Shafts--Remove
                                    Outer Casing.
              3-4 DTH Cluster      Foundation Shafts        0.04         196     0.417417        3        0        1        2        0     0.417417        0        0        0        0        0
               Drill.               for Dry Dock 1
                                    West.
33..........  3-4 Rotary Drill...  Dry Dock 1 North         0.04          18     0.000014        0        0        0        0        0     0.417417        0        0        0        0        0
                                    Leveling Piles--
                                    Install Outer
                                    Casing.
              3-4 Rotary Drill...  Dry Dock 1 West          0.04          18     0.000248        0        0        0        0        0     0.417417        0        0        0        0        0
                                    Leveling Piles--
                                    Pre-Drill Socket.
              3-4 Rotary Drill...  Dry Dock 1 North         0.04          18     0.000002        0        0        0        0        0     0.417417        0        0        0        0        0
                                    Leveling Piles--
                                    Remove Outer
                                    Casing.
              3-4 DTH Cluster      Dry Dock 1 West          0.04         135     0.417417        2        0        1        1        0     0.417417        0        0        0        0        0
               Drill.               Leveling Piles
                                    (Diving Board
                                    Shafts).
34..........  3-4 DTH Mono-hammer  Dry Dock 1 North         0.04          18     0.073751        0        0        0        0        0     0.417417        0        0        0        0        0
                                    Rock Anchors.
35..........  4-5 DTH Mono-hammer  Dry Dock 1 West          0.04          18     0.073751        0        0        0        0        0     0.417417        0        0        0        0        0
                                    Rock Anchors.
             -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Total.......  ...................  ..................  .........  ..........  ...........       29       13       10        6        0  ...........        4        3    \2\ 2        0        0
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
* Note, for the purposes of this analysis, the proposed construction years are identified as years 2 through 5; takes for marine mammals during Year 1 of the Navy's construction activities
  were authorized in a previously issued IHA (87 FR 19886; April 6, 2022).
\1\ In instances where only 1 take was calculated but activities spanned more than one construction year, one take was requested by the Navy for each construction year.
\2\ One take by Level B harassment was added to construction year 3 to account for average group size of harbor porpoises (see https://www.fisheries.noaa.gov/species/harbor-
  porpoise#:~:text=The%20harbor%20porpoise%20is%20a,estuaries%2C%20harbors%2C%20and%20fjords).
** No additional takes are expected to result from the simultaneous use of two rotary drills and a DTH mono-hammer in construction years 3 and 4 and the simultaneous use of two rotary drills
  in construction year 4.


[[Page 3179]]

    Although no construction activity is currently planned for the 
final year of the LOA period (construction year 6), potential schedule 
slips may occur as a result of equipment failure, inclement weather, or 
other unforeseen events. However, potential takes that could occur 
during year 6 as a result of delays to activities scheduled for years 
2-5 are accounted for through the analyses for those years, and no 
additional take is proposed for authorization.

Harbor Seal

    Harbor seals may be present year-round in the project vicinity, 
with consistent densities throughout the year. Harbor seals are the 
most common pinniped in the Piscataqua River near the Shipyard. 
Sightings of this species 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, 2018; Navy, 2019; NAVFAC, 2021, 2022), and 
therefore density estimates from these efforts were considered in the 
analysis. Based on observations recorded during the Berth 11 Waterfront 
Improvements (199 observations of harbor seals during year 1 and 249 
observations of harbor seals during year 2 [448 total] over 322 days) 
and P-310 project construction monitoring (721 observations of harbor 
seals during year 1 and 451 observations of harbor seals during year 2 
[1,172 total] over 349 days), harbor seal density was estimated to be 
3.0/km\2\ in the project area (Cianbro, 2018; Navy, 2019; NAVFAC, 2021, 
2022).
    Takes by Level A harassment were calculated for harbor seals where 
the density of animals (3 harbor seals/km\2\) was multiplied by the 
harassment zone and the number of days per construction activity. This 
method was deemed to be inappropriate by the Navy for calculating takes 
by Level B harassment for harbor seals as it produced take numbers that 
were lower than the number of harbor seals that has been previously 
observed in the Navy's monitoring reports. Therefore, the Navy is 
proposing (and NMFS concurs) 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 observed a day 
multiplied by the total number of construction days (i.e., 349 days), 
resulting in 1,047 takes per year by Level B harassment. This method is 
consistent with the methodology used to estimate takes by Level B 
harassment in IHA issued by NMFS for the first year of P-381 
construction activities (87 FR 19866; April 6, 2022).
    Additional takes by Level B harassment may occur during the 
simultaneous use of two rotary drills and a DTH mono-hammer in 
construction years 3 and 4 and the simultaneous use of two rotary 
drills in construction year 4. The simultaneous use of two rotary 
drills would result in 28 additional takes by Level B harassment of 
harbor seals. The simultaneous use of two rotary drills and a DTH mono-
hammer would result in 22 additional takes by Level B harassment of 
harbor seals. Note, the use of cluster drills and rock hammers in 
construction years 2 and 3 result in the entire ROI being ensonified to 
Level A harassment thresholds; therefore, there would be no change to 
the size of the harassment zones from concurrent construction 
activities during these years and thus no need to authorize additional 
takes. To account for concurrent activities in construction years 3 and 
4, the Navy is requesting to add additional takes by Level B harassment 
to their proposed take numbers (22 harbor seal in construction year 3 
and 50 harbor seal in construction year 4). Therefore the Navy requests 
1,047 takes by Level B harassment for harbor seals in construction year 
2, 1,069 takes by Level B harassment for harbor seals in construction 
year 3, 1,097 takes by Level B harassment for harbor seals in 
construction year 4, and 1,047 takes by Level B takes for harbor seals 
in construction year 5 (note the division of takes over the 
construction years is summarized in Table 12).
    Take by Level A harassment of harbor 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 potentially 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, but would be 
authorized as takes by Level A harassment. The proposed takes by Level 
B harassment were not included in Table 14 as they were calculated by a 
different method (i.e., by using the value of three harbor seals 
observed per day multiplied by the total number of construction days; 
i.e., 349 days).

                                    Table 14--Estimated Take by Level A Harassment of Harbor Seal by Project Activity
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                  Level A        Proposed take by Level A harassment
                                                                                      Total      harassment --------------------------------------------
           Activity ID               Year/activity          Purpose       Density   production      zone
                                                                                       days       (km\2\)     Total    Year 2   Year 3   Year 4   Year 5
--------------------------------------------------------------------------------------------------------------------------------------------------------
A...............................  2 Rotary Drill....  Center Wall--             3           18     0.000005        0        0        0        0        0
                                                       Install
                                                       Foundation
                                                       Support Piles.
                                  2 Rotary Drill....  Center Wall--             3           18     0.000091        0        0        0        0        0
                                                       Install
                                                       Foundation
                                                       Support Piles.
                                  2 Rotary Drill....  Center Wall--             3           18     0.000001        0        0        0        0        0
                                                       Install
                                                       Foundation
                                                       Support Piles.
                                  2 DTH Cluster       Center Wall--             3          117     0.417417      147      147        0        0        0
                                   Drill.              Install
                                                       Foundation
                                                       Support Piles.
R...............................  2 Vibratory Pile    Dry Dock 1 North          3            6       0.0002        0        0        0        0        0
                                   Driving.            Entrance--Install
                                                       Temporary
                                                       Cofferdam.
                                  2 Impact Pile       Dry Dock 1 North          3            6     0.364953        7        7        0        0        0
                                   Driving.            Entrance--Install
                                                       Temporary
                                                       Cofferdam.
1...............................  2 Hydraulic Rock    Shutter Panel             3           56     0.417417       70       70        0        0        0
                                   Hammer.             Demolition (112
                                                       panels).
2...............................  2-3 Vibratory       Remove Berth 1            3           42     0.000078        0        0        0        0        0
                                   Extraction.         Sheet Piles.
3...............................  2-3 Hydraulic Rock  Removal of Granite        3           47     0.417417       59       47       12        0        0
                                   Hammer.             Quay Wall (2,800
                                                       cy).
4...............................  2-3 Hydraulic Rock  Berth 1 Top of            3           74     0.417417       93       74       19        0        0
                                   Hammer.             Wall Demolition
                                                       for Waler Install
                                                       (320 lf).
5...............................  2 Vibratory Pile    Install Berth 1           3            8     0.000078        0        0        0        0        0
                                   Driving.            Support of
                                                       Excavation.
                                  2 Impact Pile       Berth 1 Support of        3            8     0.201158        5        5        0        0        0
                                   Driving.            Excavation.

[[Page 3180]]

 
6...............................  2 Hydraulic Rock    Mechanical Rock           3           60     0.417417       75       75        0        0        0
                                   Hammer.             Removal (700 cy)
                                                       at Berth 11 Basin
                                                       Floor.
7...............................  2 DTH Mono-hammer.  Relief Holes at           3           35     0.014413        1        1        0        0        0
                                                       Berth 11 Basin
                                                       Floor.
8...............................  2 Vibratory Pile    Install Temporary         3            4     0.000078        0        0        0        0        0
                                   Driving.            Cofferdam
                                                       Extension.
                                  2 Impact Pile       Temporary                 3            4     0.201158        2        2        0        0        0
                                   Driving.            Cofferdam
                                                       Extension.
9...............................  2 Rotary Drill....  Gantry Crane              3           16     0.000005        0        0        0        0        0
                                                       Support--Install
                                                       Outer Casing.
                                  2 Rotary Drill....  Gantry Crane              3           16     0.000091        0        0        0        0        0
                                                       Support--Pre-
                                                       Drill Socket.
                                  2 Rotary Drill....  Gantry Crane              3           16     0.000091        0        0        0        0        0
                                                       Support--Remove
                                                       Outer Casing.
                                  2 DTH Cluster       Gantry Crane              3           80     0.417417      100      100        0        0        0
                                   Drill.              Support Piles.
10..............................  2 Hydraulic Rock    Mechanical Rock           3           25     0.417417       31       31        0        0        0
                                   Hammer.             Removal (300 cy)
                                                       at Berth 1 Basin
                                                       Floor.
11..............................  2 DTH Mono-hammer.  Dry Dock 1 North          3           25     0.022912        2        2        0        0        0
                                                       Entrance Rock
                                                       Anchors.
12..............................  2 Vibratory Pile    Center Wall Tie-in        3            4     0.000078        0        0        0        0        0
                                   Driving.            to Existing West
                                                       Closure Wall.
                                  2 Impact Pile       Center Wall Tie-in        3            4     0.201158        2        2        0        0        0
                                   Driving.            to West Closure
                                                       Wall.
13..............................  2-3 Rotary Drill..  Dry Dock 1 North          3           20     0.000005        0        0        0        0        0
                                                       Temporary Work
                                                       Trestle--Install
                                                       Outer Casing.
                                  2-3 Rotary Drill..  Dry Dock 1 North          3           20     0.000091        0        0        0        0        0
                                                       Temporary Work
                                                       Trestle--Pre-
                                                       Drill Socket.
                                  2-3 Rotary Drill..  Dry Dock 1 North          3           20     0.000001        0        0        0        0        0
                                                       Temporary Work
                                                       Trestle--Remove
                                                       Outer Casing.
                                  2-3 DTH Cluster     Dry Dock 1 North          3           70     0.417417       88       53       35        0        0
                                   Drill.              Temporary Work
                                                       Trestle.
14..............................  2-3 Rotary Drill..  Remove Dry Dock 1         3           20     0.000002        0        0        0        0        0
                                                       North Temporary
                                                       Work Trestle
                                                       Piles.
15..............................  2-3 Rotary Drill..  Dry Dock 1 North          3           18     0.000005        0        0        0        0        0
                                                       Leveling Piles--
                                                       Install Outer
                                                       Casing.
                                  2-3 Rotary Drill..  Dry Dock 1 North          3           18     0.000091        0        0        0        0        0
                                                       Leveling Piles--
                                                       Pre-Drill Socket.
                                  2-3 Rotary Drill..  Dry Dock 1 North          3           18     0.000001        0        0        0        0        0
                                                       Leveling Piles--
                                                       Remove Outer
                                                       Casing.
                                  2-3 DTH Cluster     Dry Dock 1 North          3          135     0.417417      169      101       68        0        0
                                   Drill.              Leveling Piles
                                                       (Diving Board
                                                       Shafts).
16..............................  2-3 Rotary Drill..  Dry Dock 1 North          3           20     0.000005        0        0        0        0        0
                                                       Wall Shafts--
                                                       Install Outer
                                                       Casing.
                                  2-3 Rotary Drill..  Dry Dock 1 North          3           20     0.000091        0        0        0        0        0
                                                       Wall Shafts--Pre-
                                                       Drill Socket.
                                  2-3 Rotary Drill..  Dry Dock 1 North          3           20     0.000001        0        0        0        0        0
                                                       Wall Shafts--
                                                       Remove Outer
                                                       Casing.
                                  2-3 DTH Cluster     Wall Shafts for           3          150     0.417417      188      113       75        0        0
                                   Drill.              Dry Dock 1 North.
17..............................  2-3 Rotary Drill..  Dry Dock 1 North          3           23     0.000005        0        0        0        0        0
                                                       Foundation
                                                       Shafts--Install
                                                       Outer Casing.
                                  2-3 Rotary Drill..  Dry Dock 1 North          3           23     0.000091        0        0        0        0        0
                                                       Foundation
                                                       Shafts--Pre-Drill
                                                       Sockets.
                                  2-3 Rotary Drill..  Dry Dock 1 North          3           23     0.000001        0        0        0        0        0
                                                       Foundation
                                                       Shafts--Remove
                                                       Outer Casing.
                                  2-3 DTH Cluster     Foundation Shafts         3          196     0.417417      245      147       98        0        0
                                   Drill.              for Dry Dock 1
                                                       North.
18..............................  2 Vibratory         Berth 11 End Wall         3           10       0.0002        0        0        0        0        0
                                   Extraction.         Temporary Guide
                                                       Wall.
19..............................  2 Vibratory         Remove Berth 1            3            5       0.0002        0        0        0        0        0
                                   Extraction.         Support of
                                                       Excavation.
20..............................  2 Vibratory         Remove Berth 1            3           18     0.000136        0        0        0        0        0
                                   Extraction.         Emergency Repairs.
21..............................  2 Hydraulic Rock    Removal of                3           15     0.417417       19       19        0        0        0
                                   Hammer.             Emergency Repair
                                                       Concrete (500 cy)
                                                       at Berth 1.
22..............................  2-3 DTH Mono-       Center Wall               3           36     0.022912        2        1        1        0        0
                                   hammer.             Foundation Rock
                                                       Anchors.
23..............................  2-3 Vibratory       Dry Dock 1 North-         3            3       0.0002        0        0        0        0        0
                                   Extraction.         Remove Center
                                                       Wall Tie-in to
                                                       West Closure Wall.
24..............................  2-3 Vibratory Pile  Center Wall East          3           12     0.000032        0        0        0        0        0
                                   Driving.            Tie-in to
                                                       Existing Wall.
                                  2-3 Impact Pile     Center Wall East          3           12     0.090757        3        2        1        0        0
                                   Driving.            Tie-in to
                                                       Existing Wall.
25..............................  2-3 Vibratory       Dry Dock 1 West           3            3       0.0002        0        0        0        0        0
                                   Extraction.         Remove Center
                                                       Wall Tie-in to
                                                       West Closure Wall.
26..............................  2-3 Vibratory       Remove Center Wall        3           12       0.0002        0        0        0        0        0
                                   Extraction.         Tie-in to
                                                       Existing Wall.
27..............................  2-3 Vibratory       Remove Temporary          3           12       0.0002        0        0        0        0        0
                                   Extraction.         Cofferdam.

[[Page 3181]]

 
28..............................  2-3 Vibratory       Remove Temporary          3            2       0.0002        0        0        0        0        0
                                   Extraction.         Cofferdam
                                                       Extension.
29..............................  3-4 Rotary Drill..  Dry Dock 1 West           3           20     0.000005        0        0        0        0        0
                                                       Temporary Work
                                                       Trestle--Install
                                                       Outer Casing.
                                  3-4 Rotary Drill..  Dry Dock 1 West           3           20     0.000091        0        0        0        0        0
                                                       Temporary Work
                                                       Trestle--Pre-
                                                       Drill Socket.
                                  3-4 Rotary Drill..  Dry Dock 1 West           3           20     0.000001        0        0        0        0        0
                                                       Temporary Work
                                                       Trestle--Remove
                                                       Outer Casing.
                                  3-4 DTH Cluster     Dry Dock 1 West           3           70     0.417417       88        0       44       44        0
                                   Drill.              Temporary Work
                                                       Trestle.
30..............................  3-4 Rotary Drill..  Dry Dock 1 West           3           20     0.000002        0        0        0        0        0
                                                       Remove Temporary
                                                       Work Trestle
                                                       Piles.
31..............................  3-4 Rotary Drill..  Dry Dock 1 West           3           22     0.000005        0        0        0        0        0
                                                       Wall Shafts--
                                                       Install Outer
                                                       Casing.
                                  3-4 Rotary Drill..  Dry Dock 1 West           3           22     0.000091        0        0        0        0        0
                                                       Wall Shafts--Pre-
                                                       Drill Socket.
                                  3-4 Rotary Drill..  Dry Dock 1 West           3           22     0.000001        0        0        0        0        0
                                                       Wall Shafts--
                                                       Remove Outer
                                                       Casing.
                                  3-4 DTH Cluster     Wall Shafts for           3          165     0.417417      206        0      103      103        0
                                   Drill.              Dry Dock 1 West.
32..............................  3-4 Rotary Drill..  Dry Dock 1 West           3           23     0.000005        0        0        0        0        0
                                                       Foundation
                                                       Shafts--Install
                                                       Outer Casing.
                                  3-4 Rotary Drill..  Dry Dock 1 West           3           23     0.000091        0        0        0        0        0
                                                       Foundation
                                                       Shafts--Pre-Drill
                                                       Sockets.
                                  3-4 Rotary Drill..  Dry Dock 1 West           3           23     0.000001        0        0        0        0        0
                                                       Foundation
                                                       Shafts--Remove
                                                       Outer Casing.
                                  3-4 DTH Cluster     Foundation Shafts         3          196     0.417417      245        0      122      123        0
                                   Drill.              for Dry Dock 1
                                                       West.
33..............................  3-4 Rotary Drill..  Dry Dock 1 North          3           18     0.000005        0        0        0        0        0
                                                       Leveling Piles--
                                                       Install Outer
                                                       Casing.
                                  3-4 Rotary Drill..  Dry Dock 1 West           3           18     0.000091        0        0        0        0        0
                                                       Leveling Piles--
                                                       Pre-Drill Socket.
                                  3-4 Rotary Drill..  Dry Dock 1 North          3           18     0.000001        0        0        0        0        0
                                                       Leveling Piles--
                                                       Remove Outer
                                                       Casing.
                                  3-4 DTH Cluster     Dry Dock 1 West           3          135     0.417417      169        0       84       85        0
                                   Drill.              Leveling Piles
                                                       (Diving Board
                                                       Shafts).
34..............................  3-4 DTH Mono-       Dry Dock 1 North          3           18     0.022912        1        0        1        0        0
                                   hammer.             Rock Anchors.
35..............................  4-5 DTH Mono-       Dry Dock 1 West           3           18     0.022912        1        0        0        0        1
                                   hammer.             Rock Anchors.
                                                                                                            --------------------------------------------
    Total.......................  ..................  ..................  .......  ...........  ...........    2,018      999      663      355        1
--------------------------------------------------------------------------------------------------------------------------------------------------------
* Note, for the purposes of this analysis, the proposed construction years are identified as years 2 through 5; takes for marine mammals during Year 1
  of the Navy's construction activities were authorized in a previously issued IHA (87 FR 19886; April 6, 2022).

    Although no construction activity is currently planned for the 
final year of the LOA period (construction year 6), potential schedule 
slips may occur as a result of equipment failure, inclement weather, or 
other unforeseen events. However, potential takes that could occur 
during year 6 as a result of delays to activities scheduled for years 
2-5 are accounted for through the analyses for those years, and no 
additional take is proposed for authorization.

Gray Seal

    Gray seals may be present year-round in the project vicinity, with 
consistent densities throughout the year. Gray seals are less common in 
the Piscataqua River than the harbor seal. A total of nine sightings of 
gray seals were recorded during P-310 construction monitoring (NAVFAC, 
2021, 2022). Density estimates of gray seals were based on the Berth 11 
Waterfront Improvements (24 observations of gray seals during year 1 
and 12 observations of gray seals during year 2 [36 total] over 322 
days) and P-310 project construction monitoring (47 observations of 
gray seals during year 1 and 21 observations of gray seals during year 
2 [68 total] over 349 days) and was estimated to be 0.2/km\2\ (Cianbro, 
2018; Navy, 2019; NAVFAC, 2021, 2022). These data were preferred in 
this analysis over the more general density data from the NMSDD.
    Takes by Level A harassment were calculated for gray seals where 
the density of animals (0.2 gray seals/km\2\) was multiplied by the 
harassment zone and the number of days per construction activity. This 
method was deemed to be inappropriate by the Navy for calculating takes 
by Level B harassment for gray seals as it produced take that were 
fewer than the number of gray seals that has been previously observed 
in the Navy's monitoring reports. Therefore, the Navy is proposing (and 
NMFS concurs), 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 a day multiplied by the total number 
of construction days (i.e., 349 days) resulting in 70 takes by Level B 
harassment proposed for authorization per year. This method is 
consistent with the methodology used to estimate takes by Level B 
harassment in IHA issued by NMFS for the first year of P-381 
construction activities (87 FR 19866; April 6, 2022).
    Additional takes by Level B harassment may occur during the 
simultaneous use of two rotary drills and a DTH mono-hammer in 
construction years 3 and 4 and the simultaneous use of two rotary 
drills in construction year 4. The simultaneous use of two rotary 
drills would result in 2 additional Level B takes of gray seals. The 
simultaneous use of two rotary drills and a DTH mono-hammer would 
result in 1 additional Level B take of

[[Page 3182]]

gray seals. Note, the use of cluster drills and rock hammers in 
construction years 2 and 3 result in the entire ROI being ensonified to 
Level A harassment thresholds; therefore, there would be no change to 
the size of the harassment zones from concurrent construction 
activities during these years and thus no need to request additional 
takes. To account for concurrent activities in construction years 3 and 
4, the Navy is requesting additional takes by Level B harassment to 
their proposed take numbers (1 gray seal in construction year 3 and 3 
gray seals in construction year 4). Therefore the Navy requests 70 
takes by Level B takes for gray seals in construction year 2, 71 takes 
by Level B harassment for gray seals in construction year 3, 73 takes 
by Level B harassment for gray seals in construction year 4, and 70 
takes by Level B harassment for gray seals in construction year 5 (note 
the division of takes over the construction years is summarized in 
Table 12).
    Take by Level A harassment of gray seals is shown in Table 15 
below. Note that where the Level A harassment zone is as large as the 
Level B harassment zone and fills the entire potentially 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, but would be 
authorized as takes by Level A harassment. The proposed takes by Level 
B harassment were not included in Table 15 as they were calculated by a 
different method (i.e., by using the value of 0.2 gray seals observed a 
day multiplied by the total number of construction days; i.e., 349 
days).

                                Table 15--Calculated Proposed Take by Level A Harassment of Gray Seal by Project Activity
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                  Level A        Proposed take by Level A harassment
                                                                                      Total      harassment --------------------------------------------
           Activity ID               Year/activity          Purpose       Density   production      zone
                                                                                       days       (km\2\)     Total    Year 2   Year 3   Year 4   Year 5
--------------------------------------------------------------------------------------------------------------------------------------------------------
A...............................  2 Rotary Drill....  Center Wall--           0.2           18     0.000005        0        0        0        0        0
                                                       Install
                                                       Foundation
                                                       Support Piles.
                                  2 Rotary Drill....  Center Wall--           0.2           18     0.000091        0        0        0        0        0
                                                       Install
                                                       Foundation
                                                       Support Piles.
                                  2 Rotary Drill....  Center Wall--           0.2           18     0.000001        0        0        0        0        0
                                                       Install
                                                       Foundation
                                                       Support Piles.
                                  2 DTH Cluster       Center Wall--           0.2          117     0.417417       10       10        0        0        0
                                   Drill.              Install
                                                       Foundation
                                                       Support Piles.
R...............................  2 Vibratory Pile    Dry Dock 1 North        0.2            6       0.0002        0        0        0        0        0
                                   Driving.            Entrance--Install
                                                       Temporary
                                                       Cofferdam.
                                  2 Impact Pile       Dry Dock 1 North        0.2            6     0.364953        0        0        0        0        0
                                   Driving.            Entrance--Install
                                                       Temporary
                                                       Cofferdam.
1...............................  2 Hydraulic Rock    Shutter Panel           0.2           56     0.417417        5        5        0        0        0
                                   Hammer.             Demolition (112
                                                       panels).
2...............................  2-3 Vibratory       Remove Berth 1          0.2           42     0.000078        0        0        0        0        0
                                   Extraction.         Sheet Piles.
3...............................  2-3 Hydraulic Rock  Removal of Granite      0.2           47     0.417417        4        3        1        0        0
                                   Hammer.             Quay Wall (2,800
                                                       cy).
4...............................  2-3 Hydraulic Rock  Berth 1 Top of          0.2           74     0.417417        6        5        1        0        0
                                   Hammer.             Wall Demolition
                                                       for Waler Install
                                                       (320 lf).
5...............................  2 Vibratory Pile    Install Berth 1         0.2            8     0.000078        0        0        0        0        0
                                   Driving.            Support of
                                                       Excavation.
                                  2 Impact Pile       Berth 1 Support of      0.2            8     0.201158        0        0        0        0        0
                                   Driving.            Excavation.
6...............................  2 Hydraulic Rock    Mechanical Rock         0.2           60     0.417417        5        5        0        0        0
                                   Hammer.             Removal (700 cy)
                                                       at Berth 11 Basin
                                                       Floor.
7...............................  2 DTH Mono-hammer.  Relief Holes at         0.2           35     0.014413        0        0        0        0        0
                                                       Berth 11 Basin
                                                       Floor.
8...............................  2 Vibratory Pile    Install Temporary       0.2            4     0.000078        0        0        0        0        0
                                   Driving.            Cofferdam
                                                       Extension.
                                  2 Impact Pile       Temporary               0.2            4     0.201158        0        0        0        0        0
                                   Driving.            Cofferdam
                                                       Extension.
9...............................  2 Rotary Drill....  Gantry Crane            0.2           16     0.000005        0        0        0        0        0
                                                       Support--Install
                                                       Outer Casing.
                                  2 Rotary Drill....  Gantry Crane            0.2           16     0.000091        0        0        0        0        0
                                                       Support--Pre-
                                                       Drill Socket.
                                  2 Rotary Drill....  Gantry Crane            0.2           16     0.000091        0        0        0        0        0
                                                       Support--Remove
                                                       Outer Casing.
                                  2 DTH Cluster       Gantry Crane            0.2           80     0.417417        7        7        0        0        0
                                   Drill.              Support Piles.
10..............................  2 Hydraulic Rock    Mechanical Rock         0.2           25     0.417417        2        2        0        0        0
                                   Hammer.             Removal (300 cy)
                                                       at Berth 1 Basin
                                                       Floor.
11..............................  2 DTH Mono-hammer.  Dry Dock 1 North        0.2           25     0.022912        0        0        0        0        0
                                                       Entrance Rock
                                                       Anchors.
12..............................  2 Vibratory Pile    Center Wall Tie-In      0.2            4     0.000078        0        0        0        0        0
                                   Driving.            to Existing West
                                                       Closure Wall.
                                  2 Impact Pile       Center Wall Tie-in      0.2            4     0.201158        0        0        0        0        0
                                   Driving.            to West Closure
                                                       Wall.
13..............................  2-3 Rotary Drill..  Dry Dock 1 North        0.2           20     0.000005        0        0        0        0        0
                                                       Temporary Work
                                                       Trestle--Install
                                                       Outer Casing.
                                  2-3 Rotary Drill..  Dry Dock 1 North        0.2           20     0.000091        0        0        0        0        0
                                                       Temporary Work
                                                       Trestle--Pre-
                                                       Drill Socket.
                                  2-3 Rotary Drill..  Dry Dock 1 North        0.2           20     0.000001        0        0        0        0        0
                                                       Temporary Work
                                                       Trestle--Remove
                                                       Outer Casing.
                                  2-3 DTH Cluster     Dry Dock 1 North        0.2           70     0.417417        6        4        2        0        0
                                   Drill.              Temporary Work
                                                       Trestle.
14..............................  2-3 Rotary Drill..  Remove Dry Dock 1       0.2           20     0.000002        0        0        0        0        0
                                                       North Temporary
                                                       Work Trestle
                                                       Piles.
15..............................  2-3 Rotary Drill..  Dry Dock 1 North        0.2           18     0.000005        0        0        0        0        0
                                                       Leveling Piles--
                                                       Install Outer
                                                       Casing.

[[Page 3183]]

 
                                  2-3 Rotary Drill..  Dry Dock 1 North        0.2           18     0.000091        0        0        0        0        0
                                                       Leveling Piles--
                                                       Pre-Drill Socket.
                                  2-3 Rotary Drill..  Dry Dock 1 North        0.2           18     0.000001        0        0        0        0        0
                                                       Leveling Piles--
                                                       Remove Outer
                                                       Casing.
                                  2-3 DTH Cluster     Dry Dock 1 North        0.2          135     0.417417       11        7        4        0        0
                                   Drill.              Leveling Piles
                                                       (Diving Board
                                                       Shafts).
16..............................  2-3 Rotary Drill..  Dry Dock 1 North        0.2           20     0.000005        0        0        0        0        0
                                                       Wall Shafts--
                                                       Install Outer
                                                       Casing.
                                  2-3 Rotary Drill..  Dry Dock 1 North        0.2           20     0.000091        0        0        0        0        0
                                                       Wall Shafts--Pre-
                                                       Drill Socket.
                                  2-3 Rotary Drill..  Dry Dock 1 North        0.2           20     0.000001        0        0        0        0        0
                                                       Wall Shafts--
                                                       Remove Outer
                                                       Casing.
                                  2-3 DTH Cluster     Wall Shafts for         0.2          150     0.417417       13        8        5        0        0
                                   Drill.              Dry Dock 1 North.
17..............................  2-3 Rotary Drill..  Dry Dock 1 North        0.2           23     0.000005        0        0        0        0        0
                                                       Foundation
                                                       Shafts--Install
                                                       Outer Casing.
                                  2-3 Rotary Drill..  Dry Dock 1 North        0.2           23     0.000091        0        0        0        0        0
                                                       Foundation
                                                       Shafts--Pre-Drill
                                                       Sockets.
                                  2-3 Rotary Drill..  Dry Dock 1 North        0.2           23     0.000001        0        0        0        0        0
                                                       Foundation
                                                       Shafts--Remove
                                                       Outer Casing.
                                  2-3 DTH Cluster     Foundation Shafts       0.2          196     0.417417       16       10        6        0        0
                                   Drill.              for Dry Dock 1
                                                       North.
18..............................  2 Vibratory         Berth 11 End Wall       0.2           10       0.0002        0        0        0        0        0
                                   Extraction.         Temporary Guide
                                                       Wall.
19..............................  2 Vibratory         Remove Berth 1          0.2            5       0.0002        0        0        0        0        0
                                   Extraction.         Support of
                                                       Excavation.
20..............................  2 Vibratory         Remove Berth 1          0.2           18     0.000136        0        0        0        0        0
                                   Extraction.         Emergency Repairs.
21..............................  2 Hydraulic Rock    Removal of              0.2           15     0.417417        1        1        0        0        0
                                   Hammer.             Emergency Repair
                                                       Concrete (500 cy)
                                                       at Berth 1.
22..............................  2-3 DTH Mono-       Center Wall             0.2           36     0.022912        0        0        0        0        0
                                   hammer.             Foundation Rock
                                                       Anchors.
23..............................  2-3 Vibratory       Dry Dock 1 North-       0.2            3       0.0002        0        0        0        0        0
                                   Extraction.         Remove Center
                                                       Wall Tie-in to
                                                       West Closure Wall.
24..............................  2-3 Vibratory Pile  Center Wall East        0.2           12     0.000032        0        0        0        0        0
                                   Driving.            Tie-in to
                                                       Existing Wall.
                                  2-3 Impact Pile     Center Wall East        0.2           12     0.090757        0        0        0        0        0
                                   Driving.            Tie-in to
                                                       Existing Wall.
25..............................  2-3 Vibratory       Dry Dock 1 West         0.2            3       0.0002        0        0        0        0        0
                                   Extraction.         Remove Center
                                                       Wall Tie-in to
                                                       West Closure Wall.
26..............................  2-3 Vibratory       Remove Center Wall      0.2           12       0.0002        0        0        0        0        0
                                   Extraction.         Tie-in to
                                                       Existing Wall.
27..............................  2-3 Vibratory       Remove Temporary        0.2           12       0.0002        0        0        0        0        0
                                   Extraction.         Cofferdam.
28..............................  2-3 Vibratory       Remove Temporary        0.2            2       0.0002        0        0        0        0        0
                                   Extraction.         Cofferdam
                                                       Extension.
29..............................  3-4 Rotary Drill..  Dry Dock 1 West         0.2           20     0.000005        0        0        0        0        0
                                                       Temporary Work
                                                       Trestle--Install
                                                       Outer Casing.
                                  3-4 Rotary Drill..  Dry Dock 1 West         0.2           20     0.000091        0        0        0        0        0
                                                       Temporary Work
                                                       Trestle--Pre-
                                                       Drill Socket.
                                  3-4 Rotary Drill..  Dry Dock 1 West         0.2           20     0.000001        0        0        0        0        0
                                                       Temporary Work
                                                       Trestle--Remove
                                                       Outer Casing.
                                  3-4 DTH Cluster     Dry Dock 1 West         0.2           70     0.417417        6        0        3        3        0
                                   Drill.              Temporary Work
                                                       Trestle.
30..............................  3-4 Rotary Drill..  Dry Dock 1 West         0.2           20     0.000002        0        0        0        0        0
                                                       Remove Temporary
                                                       Work Trestle
                                                       Piles.
31..............................  3-4 Rotary Drill..  Dry Dock 1 West         0.2           22     0.000005        0        0        0        0        0
                                                       Wall Shafts--
                                                       Install Outer
                                                       Casing.
                                  3-4 Rotary Drill..  Dry Dock 1 West         0.2           22     0.000091        0        0        0        0        0
                                                       Wall Shafts--Pre-
                                                       Drill Socket.
                                  3-4 Rotary Drill..  Dry Dock 1 West         0.2           22     0.000001        0        0        0        0        0
                                                       Wall Shafts--
                                                       Remove Outer
                                                       Casing.
                                  3-4 DTH Cluster     Wall Shafts for         0.2          165     0.417417       14        0        7        7        0
                                   Drill.              Dry Dock 1 West.
32..............................  3-4 Rotary Drill..  Dry Dock 1 West         0.2           23     0.000005        0        0        0        0        0
                                                       Foundation
                                                       Shafts--Install
                                                       Outer Casing.
                                  3-4 Rotary Drill..  Dry Dock 1 West         0.2           23     0.000091        0        0        0        0        0
                                                       Foundation
                                                       Shafts--Pre-Drill
                                                       Sockets.
                                  3-4 Rotary Drill..  Dry Dock 1 West         0.2           23     0.000001        0        0        0        0        0
                                                       Foundation
                                                       Shafts--Remove
                                                       Outer Casing.
                                  3-4 DTH Cluster     Foundation Shafts       0.2          196     0.417417       16        0        8        8        0
                                   Drill.              for Dry Dock 1
                                                       West.
33..............................  3-4 Rotary Drill..  Dry Dock 1 North        0.2           18     0.000005        0        0        0        0        0
                                                       Leveling Piles--
                                                       Install Outer
                                                       Casing.
                                  3-4 Rotary Drill..  Dry Dock 1 West         0.2           18     0.000091        0        0        0        0        0
                                                       Leveling Piles--
                                                       Pre-Drill Socket.
                                  3-4 Rotary Drill..  Dry Dock 1 North        0.2           18     0.000001        0        0        0        0        0
                                                       Leveling Piles--
                                                       Remove Outer
                                                       Casing.

[[Page 3184]]

 
                                  3-4 DTH Cluster     Dry Dock 1 West         0.2          135     0.417417       11        0        6        5        0
                                   Drill.              Leveling Piles
                                                       (Diving Board
                                                       Shafts).
34..............................  3-4 DTH Mono-       Dry Dock 1 North        0.2           18     0.022912        0        0        0        0        0
                                   hammer.             Rock Anchors.
35..............................  4-5 DTH Mono-       Dry Dock 1 West         0.2           18     0.022912        0        0        0        0        0
                                   hammer.             Rock Anchors.
                                                                                                            --------------------------------------------
    Total.......................                                          .......  ...........  ...........      133       67       43       23        0
--------------------------------------------------------------------------------------------------------------------------------------------------------
* Note, for the purposes of this analysis, the proposed construction years are identified as years 2 through 5; takes for marine mammals during Year 1
  of the Navy's construction activities were authorized in a previously issued IHA (87 FR 19886; April 6, 2022).

    Although no construction activity is currently planned for the 
final year of the LOA period (construction year 6), potential schedule 
slips may occur as a result of equipment failure, inclement weather, or 
other unforeseen events. However, potential takes that could occur 
during year 6 as a result of delays to activities scheduled for years 
2-5 are accounted for through the analyses for those years, and no 
additional take is proposed for authorization.

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. NMFS authorized one take by Level B harassment 
per month from January to May of a hooded seal for the Berth 11 
Waterfront Improvements Construction project (NMFS, 2018b) and for P-
310 (Super Flood Basin) (NMFS, 2016; NMFS, 2019; NMFS 2021c). To date, 
the monitoring for those projects and for the density surveys have not 
recorded a sighting of hooded seal in the project area (Cianbro, 2018; 
NAVFAC Mid-Atlantic, 2018, 2019b; Navy 2019; NAVFAC, 2021, 2022). In 
order to guard against the potential for unauthorized take, the Navy is 
again requesting one take by Level B harassment of hooded seal per 
month (between the months of January and May) for each construction 
year. This will result in five takes by Level B harassment per year. 
Given the size of the shutdown zones in relation to the Level A 
harassment isopleths (see the Proposed Mitigation section below), NMFS 
also proposes to authorize five takes by Level A harassment per year to 
safeguard against unauthorized take of hooded seals that may occur 
unnoticed in the Level A harassment zone for sufficient duration to 
incur PTS.

Harp Seal

    In general, harp seals are much rarer than the harbor seal and gray 
seal in the Piscataqua River. Harp seals were not observed during 
marine mammal monitoring or survey events that took place in 2017, 
2018, or 2021 (Cianbro, 2018; NAVFAC Mid-Atlantic, 2018, 2019b; Navy, 
2019; NAVFAC, 2021, 2022); however, two harp seals (n =2) were observed 
in the River in 2020 (Stantec, 2020), and another harp seal was 
observed in 2016 (NAVFAC Mid-Atlantic, 2016; NMFS, 2016). As above for 
hooded seals, the Navy is proposing one take by Level B harassment of 
harp seal per month of construction (between the months of January and 
May) for each construction year as was authorized by NMFS for the Berth 
11 Waterfront Improvements Project (NMFS, 2018b) and for P-310 (Super 
Flood Basin) construction activities (NMFS, 2019, 2021a). Harp seals 
may occur in the area from January through May. Anticipating one Level 
B harassment harp seal take per month for 5 months per year during in-
water construction would guard against potential unauthorized take of 
this species. Given the size of the shutdown zones in relation to the 
Level A harassment isopleths (see the Proposed Mitigation section 
below), NMFS also proposes to authorize five takes by Level A 
harassment per year to safeguard against unauthorized take of harp 
seals that may occur unnoticed in the Level A harassment zone for 
sufficient duration to incur PTS.
    Table 16 below summarizes the authorized take for all the species 
described above as a percentage of stock abundance.

                                          Table 16--Proposed Take Estimates as a Percentage of Stock Abundance
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                             Annual       Annual
                                                                                                            proposed     proposed     Total     Percent
            Construction year                        Species                      Stock (NEST)              Level A      Level B     proposed   of stock
                                                                                                           harassment   harassment     take
--------------------------------------------------------------------------------------------------------------------------------------------------------
2--Apr 2023-Mar 2024.....................  Harbor porpoise............  Gulf of Maine/Bay of Fundy                 13            3         16       0.02
                                                                         (95,543).
                                           Harbor seal................  Western North Atlantic (61,336).          999        1,047      2,046       3.33
                                           Gray seal..................  Western North Atlantic (451,600)           67           70        137       0.03
                                           Harp seal..................  Western North Atlantic (7.6                 5            5         10      <0.01
                                                                         million).
                                           Hooded seal................  Western North Atlantic (593,500)            5            5         10      <0.01
3--Apr 2024-Mar 2025.....................  Harbor porpoise............  Gulf of Maine/Bay of Fundy                 10            2         12       0.01
                                                                         (95,543).
                                           Harbor seal................  Western North Atlantic (61,336).          663        1,069      1,732       2.82
                                           Gray seal..................  Western North Atlantic (451,600)           43           71        114       0.03
                                           Harp seal..................  Western North Atlantic (7.6                 5            5         10      <0.01
                                                                         million).
                                           Hooded seal................  Western North Atlantic (593,500)            5            5         10      <0.01
4--Apr 2025-Mar 2026.....................  Harbor porpoise............  Gulf of Maine/Bay of Fundy                  6            0          6       0.01
                                                                         (95,543).
                                           Harbor seal................  Western North Atlantic (61,336).          355        1,097      1,452       2.37
                                           Gray seal..................  Western North Atlantic (451,600)           23           73         96       0.02

[[Page 3185]]

 
                                           Harp seal..................  Western North Atlantic (7.6                 5            5         10      <0.01
                                                                         million).
                                           Hooded seal................  Western North Atlantic (593,500)            5            5         10      <0.01
5--Apr 2026-Mar 2027.....................  Harbor porpoise............  Gulf of Maine/Bay of Fundy                  0            0          0          0
                                                                         (95,543).
                                           Harbor seal................  Western North Atlantic (61,336).            1        1,047      1,048       1.71
                                           Gray seal..................  Western North Atlantic (451,600)            0           70         70       0.02
                                           Harp seal..................  Western North Atlantic (7.6                 5            5         10      <0.01
                                                                         million).
                                           Hooded seal................  Western North Atlantic (593,500)            5            5         10      <0.01
6--Apr 2027-Mar 2028.....................  Harbor porpoise............  Gulf of Maine/Bay of Fundy                  0            0          0      <0.01
                                                                         (95,543).
                                           Harbor seal................  Western North Atlantic (61,336).            0            0          0      <0.01
                                           Gray seal..................  Western North Atlantic (451,600)            0            0          0      <0.01
                                           Harp seal..................  Western North Atlantic (7.6                 0            0          0      <0.01
                                                                         million).
                                           Hooded seal................  Western North Atlantic (593,500)            0            0          0      <0.01
Total Estimated Proposed Take \1\........  Harbor porpoise............  Gulf of Maine/Bay of Fundy                 29            5         34         NA
                                                                         (95,543).
                                           Harbor seal................  Western North Atlantic (61,336).        2,018        4,260      6,278         NA
                                           Gray seal..................  Western North Atlantic (451,600)          133          284        438         NA
                                           Harp seal..................  Western North Atlantic (7.6                25           25         50         NA
                                                                         million).
                                           Hooded seal................  Western North Atlantic (593,500)           25           25         50         NA
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ The total estimated proposed take does not include take that may occur in year six as a result of schedule delays, as these potential takes are
  already accounted for in previous years.

Proposed Mitigation

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

General

    In-water construction activities must 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 met, entering or within the 
harassment zone. If such circumstances recur, the Navy will consult 
with NMFS concerning the potential need for an additional take 
authorization.

Coordination

    The Navy shall conduct briefings between construction supervisors 
and crews, the marine mammal monitoring team, and Navy staff prior to 
the start of in-water construction activities and when new personnel 
join the work, to ensure that responsibilities, communication 
procedures, marine mammal monitoring protocols, and operational 
procedures are clearly understood.

Soft Start

    The Navy shall use soft start techniques when impact pile driving. 
The objective of a soft start is to provide a warning and/or give 
animals in close proximity to pile-driving a chance to leave the area 
prior to an impact driver operating at full capacity, thereby exposing 
fewer animals to loud underwater and airborne sounds. Soft start 
requires contractors to provide an initial set of strikes from the 
impact hammer at reduced energy, followed by a 30-second waiting 
period, then two subsequent reduced-energy strike sets. Note the number 
of strikes will vary at reduced energy because raising the hammer at 
less than full power and then releasing it results in the hammer 
``bouncing'' as it strikes the pile, resulting in multiple ``strikes.'' 
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 applicable to other 
in-water construction activities.

Bubble Curtain

    During construction of the multifunctional expansion of Dry Dock 1, 
portions of the west closure wall and/or the super flood basin caisson 
gate may not be in place. A bubble curtain would be installed across 
the entrance openings to mitigate underwater noise impacts outside of 
the basin for those activities where Level A harassment thresholds are 
achieved across the entire ROI (i.e., cluster drill and hydraulic rock

[[Page 3186]]

hammering (Table 7)). A bubble curtain similar to the one employed 
during P-310 blasting activities and proposed for use during P-381 year 
1 construction is proposed to be used to minimize potential impacts 
outside of the basin. Hydroacoustic monitoring would be conducted 
inside of the bubble curtain to measure construction generated noise 
levels. Should the results of the recordings inside the bubble curtain 
show that the source levels do not result in the Level A harassment 
thresholds being achieved across the entire ROI by the activity 
occurring, upon review of the data by NMFS, the Navy may discontinue 
use of the bubble curtain for those activities that are not actually 
exceeding thresholds. The bubble curtain must adhere to the following 
restrictions:
     The bubble curtain must distribute air bubbles around 100 
percent of the piling circumference for the full depth of the water 
column;
     The lowest bubble ring must be in contact with the 
substrate for the full circumference of the ring, and the weights 
attached to the bottom ring shall ensure 100 percent substrate contact. 
No parts of the ring or other objects shall prevent full substrate 
contact; and
     Air flow to the bubblers must be balanced around the 
circumference of the pile;

Avoiding Direct Physical Interaction

    During all in-water construction activities, in order to prevent 
injury from physical interaction with construction equipment, a 
shutdown zone of 10 m (33 ft) will be implemented. If a marine mammal 
comes within 10 m (33 ft) of such activity, operations shall cease and 
vessels will reduce speed to the minimum level required to maintain 
steerage and safe working conditions. If human safety is at risk, the 
in-water activity will be allowed to continue until it is safe to stop.

Shutdown Zones

    The Navy shall establish shutdown zones for all in-water 
construction 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 17). The shutdown zone distances 
for rock hammering, impact pile-driving of sheet piles, and DTH 
excavation (200 m (656 ft) for harbor porpoise and 50 m (164 ft) for 
seals) are consistent with those implemented for the same activities 
for P-381 year 1 construction activities (NMFS, 2022a; 87 FR 19886). 
NMFS has preliminarily determined that these shutdown zones represent 
the largest area that can practicably be monitored.

               Table 17--Pile Driving Shutdown Zone and Monitoring Zones During Project Activities
----------------------------------------------------------------------------------------------------------------
                                                                        Shutdown zone (m)
                                                                -------------------------------- Monitoring zone
           LOA year              Activity, size, and component       Harbor                        \1\  (km\2\)
                                                                    porpoise          Seals
----------------------------------------------------------------------------------------------------------------
2.............................  Rock Hammering \2\.............             200              50  ROI.\3\
2.............................  Impact Pile Driving--8 sheet                200              50  ROI.\4\
                                 piles per day.
2.............................  Impact Pile Driving--4 sheet                200              50  ROI.\4\
                                 piles per day.
2/3...........................  Impact Pile Driving--2 sheet                200              50  ROI.\4\
                                 piles per day.
2/3...........................  Vibratory Pile Driving/                      20              10  ROI.\4\
                                 Extraction--8 sheet piles per
                                 day.
2.............................  Vibratory Pile Driving/                      20              10  ROI.\4\
                                 Extraction--6 sheet piles per
                                 day.
2.............................  Vibratory Pile Driving/                      15              10  ROI.\4\
                                 Extraction--4 sheet piles per
                                 day.
2/3...........................  Vibratory Pile Driving/                      10              10  ROI.\4\
                                 Extraction--2 sheet piles per
                                 day.
2.............................  DTH mono-hammer 4-6 inch relief             180              50  ROI.\4\
                                 holes.
2/3/4/5.......................  DTH mono-hammer 9-inch rock                 200              50  ROI.\4\
                                 anchors for tie-downs.
2/3/4.........................  Rotary Drilling--1 hour to set               10              10  ROI.\4\
                                 casings.
2/3/4.........................  Rotary drilling--9 hours to                  10              10  ROI.\4\
                                 drill socket.
2/3/4.........................  Rotary Drilling--15 minutes to               10              10  ROI.\4\
                                 remove casings and.
                                temporary work trestle piles...
2/3/4.........................  Cluster Drilling \2\...........             200              50  ROI.\3\ \4\
----------------------------------------------------------------------------------------------------------------
Notes:
\1\ In instances where the harassment zone is larger than the region of influence (ROI), the entire ROI is
  indicated as the limit of monitoring (see Figure 1-3 in the Navy's application).
\2\ Activities will employ a bubble curtain to reduce underwater noise impacts outside of the basin.
\3\ The entire ROI would be ensonified to the Level A threshold.
\4\ The entire ROI would be ensonified to the Level B threshold.

    The Navy must delay or shutdown in-water construction activities 
should a marine mammal approach or enter the appropriate shutdown zone. 
The Navy may resume activities after one of the following conditions 
have been met: (1) the animal is observed exiting the shutdown zone; 
(2) the animal is thought to have exited the shutdown zone based on a 
determination of its course, speed, and movement relative to the pile 
driving location; or (3) the shutdown zone has been clear from any 
additional sightings for 15 minutes.

Protected Species Observers

    The Navy shall employ at least three protected species observers 
(PSOs) to monitor marine mammal presence in the action area during all 
in-water construction activities. Additional PSOs may be added if 
warranted by site conditions (rough seas, rain) and the level of marine 
mammal activity. All PSOs will be approved by NMFS and the Navy prior 
to starting work as a PSO. PSOs must track marine mammals observed 
anywhere within their visual range relative to in-water construction 
activities, and estimate the amount of time a marine mammal spends 
within the Level A or Level B harassment zones while construction 
activities are underway.
    Monitoring must take place from 30 minutes prior to initiation of 
pile driving or drilling activity (i.e., pre-start clearance 
monitoring) through 30 minutes post-completion of pile driving or 
drilling activity. Pre-start clearance monitoring must be conducted for 
30 minutes to ensure that the shutdown zones indicated in Table 17 are 
clear of

[[Page 3187]]

marine mammals, and pile driving or drilling may commence when 
observers have declared the shutdown zone clear of marine mammals. 
Monitoring must occur throughout the time required to drive/drill a 
pile. If work ceases for more than 30 minutes, the pre-start clearance 
monitoring of the shutdown zones must commence. A determination that 
the shutdown zone is clear must be made during a period of good 
visibility (i.e., the entire shutdown zone and surrounding waters must 
be visible to the naked eye).
    The placement of PSOs during all pile driving and drilling 
activities (described in the Proposed Monitoring and Reporting section) 
must ensure that the entire shutdown zone and Level A harassment zone 
is visible during pile driving and drilling. Should environmental 
conditions deteriorate such that marine mammals within the entire 
shutdown zone or Level A harassment zone would not be visible (e.g., 
fog, heavy rain), in-water construction activities must be delayed 
until the PSO is confident marine mammals within the shutdown zone or 
Level A harassment zone could be detected. However, if work on a pile 
has already begun, work is allowed to continue until that pile is 
installed.
    If an in-water construction activity is delayed or halted due to 
the presence of a marine mammal, the activity may not commence or 
resume until either the animal has voluntarily exited and been visually 
confirmed beyond the shutdown zone indicated in Table 17 or 15 minutes 
have passed without re-detection of the animal. If in-water 
construction activities cease for more than 30 minutes, the pre-
activity monitoring of the shutdown zone must commence.
    Based on our evaluation of the applicant's proposed measures, NMFS 
has preliminarily determined that the proposed mitigation measures 
provide the means of effecting the least practicable impact on the 
affected species or stocks and their habitat, paying particular 
attention to rookeries, mating grounds, and areas of similar 
significance.

Proposed Monitoring and Reporting

    In order to issue an LOA for an activity, section 101(a)(5)(A) of 
the MMPA states that NMFS must set forth requirements pertaining to the 
monitoring and reporting of such taking. The MMPA implementing 
regulations at 50 CFR 216.104(a)(13) indicate that requests for 
authorizations must include the suggested means of accomplishing the 
necessary monitoring and reporting that will result in increased 
knowledge of the species and of the level of taking or impacts on 
populations of marine mammals that are expected to be present while 
conducting the activities. Effective reporting is critical both to 
compliance as well as ensuring that the most value is obtained from the 
required monitoring.
    Under the MMPA implementing regulations, monitoring and reporting 
requirements prescribed by NMFS should contribute to improved 
understanding of one or more of the following:
     Occurrence of marine mammal species or stocks in the area 
in which take is anticipated (e.g., presence, abundance, distribution, 
density);
     Nature, scope, or context of likely marine mammal exposure 
to potential stressors/impacts (individual or cumulative, acute or 
chronic), through better understanding of: (1) action or environment 
(e.g., source characterization, propagation, ambient noise); (2) 
affected species (e.g., life history, dive patterns); (3) co-occurrence 
of marine mammal species with the activity; or (4) biological or 
behavioral context of exposure (e.g., age, calving or feeding areas);
     Individual marine mammal responses (behavioral or 
physiological) to acoustic stressors (acute, chronic, or cumulative), 
other stressors, or cumulative impacts from multiple stressors;
     How anticipated responses to stressors impact either: (1) 
long-term fitness and survival of individual marine mammals; or (2) 
populations, species, or stocks;
     Effects on marine mammal habitat (e.g., marine mammal prey 
species, acoustic habitat, or other important physical components of 
marine mammal habitat); and,
     Mitigation and monitoring effectiveness.
    The Navy shall submit a Marine Mammal Monitoring Plan to NMFS for 
approval in advance of the start of the construction covered by this 
proposed rule. The plan will incorporate all monitoring and mitigation 
measures and reporting requirements of the incidental take regulations.

Monitoring Zones

    The Navy shall conduct monitoring to include the entire ROI, which 
includes 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 
hydraulic rock hammering, and the 120 dB RMS threshold during vibratory 
pile driving, rotary drilling, and DTH) (see Table 7 and 8). 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 these 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.

Protected Species Observer (PSO) Monitoring Requirements and Locations

    PSOs shall be responsible for monitoring the shutdown zones, the 
monitoring zones and the pre-clearance zones, as well as effectively 
documenting takes by Level A and B harassment. 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 construction 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 Navy's application). The PSOs must record all 
observations of marine mammals, regardless of distance from the in-
water construction activity.
    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 in-water construction activities 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

[[Page 3188]]

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 proposed 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 
effort to measure SPLs from in-water construction activities not 
previously monitored as part of P-310 or as part of P-381 year 1 
construction. The Navy will collect and evaluate acoustic sound record 
levels for the rock excavation (rotary drilling or DTH excavation) 
activities conducted up to a maximum limit of 10 piles/holes. One 
hydrophone would be placed at locations 10 m (33 ft) from the noise 
source and a second hydrophone would be placed at a representative 
monitoring location at an intermediate distance between the cetacean 
and phocid shutdown zones. These locations would be adhered to as 
practicable given safety considerations and levels of activity in the 
basin. For the 10 rock excavation (rotary drilling or DTH excavation) 
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 (NMFS, 
2012).
    [ssquf] Hydroacoustic monitoring will be conducted for each type of 
activity not previously monitored under P-310 or the P-381 year 1 IHA 
up to a maximum limit of 10 piles/holes (Table 18). 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 TL for each separate in-
water construction activity. With NMFS concurrence, these measurements 
may be used to recalculate the limits of shutdown and Level A and Level 
B harassment zones, as appropriate. Hydrophones will be placed in the 
same manner as for P-310 construction activities. Locations of 
hydroacoustic recordings will be collected via global positioning 
system. 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 or chain 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.

                                   Table 18--Hydroacoustic Monitoring Summary
----------------------------------------------------------------------------------------------------------------
                                          Number  installed/       Method of install/
         Pile type/shaft size                  removed                  removal              Number monitored
----------------------------------------------------------------------------------------------------------------
126-inch shaft.......................                      138  Rotary Drill...........                       10
84-inch shaft........................                      148  Rotary Drill...........                       10
108-inch shaft.......................                       46  DTH Cluster Drill......                       10
84-inch shaft........................                       40  DTH Cluster Drill......                       10
72-inch shaft........................                       16  DTH Cluster Drill......                       10
----------------------------------------------------------------------------------------------------------------

    [ssquf] Each hydrophone 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:
    [cir] Maximum peak sound 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 sound 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] Median integration time used to calculate SPL RMS (for 
vibration monitoring, the time period selected is 1-second intervals. 
For impulsive

[[Page 3189]]

monitoring, the time period is 90% of the energy pulse duration).
    [cir] A frequency spectrum (power spectral density) (dB re 
[mu]Pa\2\ per Hz) based on allstrikes 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).

Maine Mammal Monitoring Reporting

    The Navy shall submit annual draft reports to NMFS for each 
construction year within 90 calendar days of the completion of marine 
mammal monitoring as well as a draft 5-year comprehensive summary 
report at the end of the project. The report(s) will detail the 
monitoring protocol and summarize the data recorded during monitoring. 
Annual reports will also include results from acoustic monitoring (see 
below). Final annual report(s) (each portion of the project and 
comprehensive) must be prepared and submitted to NMFS within 30 days 
following resolution of any NMFS comments on the draft reports. 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.
    A draft five-year comprehensive summary report shall be submitted 
to NMFS 90 days after the expiration of the regulations. The draft 
report would synthesize the data recorded during hydroacoustic and 
marine mammal monitoring. NMFS would provide comments within 30 days 
after receiving this draft report, and the Navy would address the 
comments and submit revisions within 30 days of receipt. If no comment 
is received from NMFS within 30 days, the draft report would be 
considered as final.
    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/shafts were driven and by 
what method (e.g., impact, vibratory, rotary drilling, rock hammering, 
mono- or cluster-DTH); and
    [cir] Total duration of driving time for each pile/hole (vibratory 
driving, rotary drilling) and number of strikes for each pile/hole 
(impact driving, hydraulic rock hammering); and
    [cir] For DTH excavation, the duration of operation for both 
impulsive and non-pulse components, as well as the strike rate.
    [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 relative 
to the in-water construction activity for each sighting (if the in-
water construction 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 each 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] Number of marine mammals detected within the harassment 
zones, by species;
    [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.
    The draft and final reports must also contain the informational 
elements described in the Hydroacoustic Monitoring Plan which, at 
minimum, must include:
    [ssquf] Hydrophone equipment and methods: recording device, 
sampling 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);
    [ssquf] One-third octave band spectrum and power spectral density 
plot; and
    [ssquf] General Daily Site Conditions
    [cir] Date and time of activities;
    [cir] Water conditions (e.g., sea state, tidal state); and
    [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. The incident 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;

[[Page 3190]]

    [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.
    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 proposed rule. The Navy shall not 
resume their activities until notified by NMFS that they can continue.

Negligible Impact Analysis and Determination

    NMFS has defined negligible impact as an impact resulting from the 
specified activity that cannot be reasonably expected to, and is not 
reasonably likely to, adversely affect the species or stock through 
effects on annual rates of recruitment or survival (50 CFR 216.103). A 
negligible impact finding is based on the lack of likely adverse 
effects on annual rates of recruitment or survival (i.e., population-
level effects). An estimate of the number of takes alone is not enough 
information on which to base an impact determination. In addition to 
considering estimates of the number of marine mammals that might be 
``taken'' through harassment, NMFS considers other factors, such as the 
likely nature of any impacts or responses (e.g., intensity, duration), 
the context of any impacts or responses (e.g., critical reproductive 
time or location, foraging impacts affecting energetics), as well as 
effects on habitat, and the likely effectiveness of the mitigation. We 
also assess the number, intensity, and context of estimated takes by 
evaluating this information relative to population status. Consistent 
with the 1989 preamble for NMFS' implementing regulations (54 FR 40338; 
September 29, 1989), the impacts from other past and ongoing 
anthropogenic activities are incorporated into this analysis via their 
impacts on the baseline (e.g., as reflected in the regulatory status of 
the species, population size and growth rate where known, ongoing 
sources of human-caused mortality, or ambient noise levels).
    To avoid repetition, this introductory discussion of our analysis 
applies to all the species listed in Table 3, given that many of the 
anticipated effects of this project on different marine mammal stocks 
are expected to be relatively similar in nature. Where there are 
meaningful differences between species or stocks, or groups of species, 
in anticipated individual responses to activities, impact of expected 
take on the population due to differences in population status, or 
impacts on habitat, they are described independently in the analysis 
below.
    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.
    The Navy's proposed activities and associated impacts will occur 
within a limited, confined area of the stocks' range. 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. The implementation of a soft 
start and a bubble curtain during some activities, along with other 
mitigation and monitoring measures already described, are expected to 
minimize the effects of the expected takes on the affected individuals. 
In addition, NMFS does not anticipate that serious injury or mortality 
will occur as a result of the Navy's planned activity given the nature 
of the activity, even in the absence of required mitigation.
    Exposures to elevated sound levels produced during pile driving and 
drilling may cause behavioral disturbance of some individuals. 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 speeds, increased 
surfacing time, or decreased foraging (if such activity were occurring) 
(e.g., Thorson and Reyff, 2006). Marine mammals within the Level B 
harassment zones may not show any visual cues they are disturbed by 
activities or they could become alert, avoid the area, leave the area, 
or display other mild responses that are not observable such as changes 
in vocalization patterns or increased haul out time (Thorson and Reyff, 
2006). Data from recent observations of harbor seals in the project 
area support the assumption that may behavioral responses to the 
proposed construction monitoring may be mild in nature (Navy, 2022). 
The Navy has observed 116 harbor seals in the project since January 20, 
2022. This includes observations at the conclusion of P-310 
construction (January to February 2022) and the start of P-381 
construction (May 2022 through October 16, 2022). Forty-eight of these 
observations occurred during periods with active construction, and the 
most common behavior recorded (n=28; 58.3 percent) was no response. The 
other common behaviors noted for these observations were swimming or 
milling (n=18; 37.5 percent), with notably lower observations of 
retreat/flush behaviors (n=1, 2.1 percent) (Navy, 2022).
    Additionally, some of the species present in the region will only 
be present temporarily based on seasonal patterns or during transit 
between other habitats. These temporarily present species will be 
exposed to even smaller periods of noise-generating activity, further 
decreasing the impacts. 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. The intensity of Level B harassment events 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. The Navy will use 
at least three PSOs stationed strategically to increase detectability 
of marine mammals during in-water construction activities and removal, 
enabling a high rate of success in implementation of shutdowns to avoid 
or minimize injury for most species. Further, given the absence of any 
major rookeries and only one isolated pinniped haul-out site at Hicks 
Rocks approximately 2.4 km (1.5 mi) from the proposed project area, we 
assume that potential takes by Level B harassment would have a 
negligible short-term effect on individuals and would not result in 
population-level impacts.
    Due to the levels and durations of likely exposure, animals that 
experience PTS will likely only receive slight PTS,

[[Page 3191]]

i.e., minor degradation of hearing capabilities within regions of 
hearing that align most completely with the frequency range of the 
energy produced by Navy's proposed in-water construction activities 
(i.e., the low-frequency region below 2 kHz), not severe hearing 
impairment or impairment in the reigns of greatest hearing sensitivity. 
If hearing impairment does occur, it is most likely that the affected 
animal will lose a few dBs in its hearing sensitivity, which in most 
cases is not likely to meaningfully affect its ability to forage and 
communicate with conspecifics. 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 
Hicks Rocks, located approximately 2.4 km (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, and does not 
include habitat of particular importance. 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 any of the species 
or stocks through effects on annual rates of recruitment or survival:
    [ssquf] No serious injury or mortality is anticipated or proposed 
for authorization;
    [ssquf] Level A harassment proposed for authorization 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., soft starts, 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] There is one pinniped haulout in the vicinity of the 
project area (Hicks Rocks), 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 proposed monitoring and 
mitigation measures, NMFS preliminarily 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 previously, only small numbers of incidental take may be 
authorized under sections 101(a)(5)(A) and (D) of the MMPA for 
specified activities other than military readiness activities. The MMPA 
does not define small numbers and so, in practice, where estimated 
numbers are available, NMFS compares the number of individuals taken to 
the most appropriate estimation of abundance of the relevant species or 
stock in our determination of whether an authorization is limited to 
small numbers of marine mammals. When the predicted number of 
individuals to be taken is fewer than one-third of the species or stock 
abundance, the take is considered to be of small numbers. Additionally, 
other qualitative factors may be considered in the analysis, such as 
the temporal or spatial scale of the activities.
    The maximum annual amount of take NMFS proposes to authorize for 
five marine mammal stocks is below one-third of the estimated stock 
abundance for all species (see 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 proposed mitigation and monitoring measures) and the 
anticipated take of marine mammals, NMFS preliminarily finds that small 
numbers of marine mammals would be taken relative to the population 
size of the affected species or stocks.

Unmitigable Adverse Impact Analysis and Determination

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

Adaptive Management

    The regulations governing the take of marine mammals incidental to 
Navy construction activities would contain an adaptive management 
component. The reporting requirements associated with this proposed 
rule are designed to provide NMFS with monitoring data from completed 
projects to allow consideration of whether any changes are appropriate. 
The use of adaptive management allows NMFS to consider new information 
from different sources to determine (with input from the Navy regarding 
practicability) on an annual or biennial basis if mitigation or 
monitoring measures should be modified (including additions or 
deletions). Mitigation measures could be modified if new data suggests 
that such modifications would have a reasonable likelihood of reducing 
adverse effects to marine mammals and if the measures are practicable.
    The following are some of the possible sources of applicable data 
to be considered through the adaptive management process: (1) Results 
from monitoring reports, as required by

[[Page 3192]]

MMPA authorizations; (2) results from general marine mammal and sound 
research; and (3) any information which reveals that marine mammals may 
have been taken in a manner, extent, or number not authorized by these 
regulations or subsequent LOAs.

Endangered Species Act

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

Request for Information

    NMFS requests that interested persons submit comments, information, 
and suggestions concerning the Navy's request and the proposed 
regulations (see ADDRESSES). All comments will be reviewed and 
evaluated as we prepare a final rule and make final determinations on 
whether to issue the requested authorization. This notice of proposed 
rulemaking and supporting documents provide all environmental 
information relating to our proposed action for public review.

Classification

    Pursuant to the procedures established to implement Executive Order 
12866, the Office of Management and Budget has determined that this 
proposed rule is not significant.
    Pursuant to section 605(b) of the Regulatory Flexibility Act (RFA), 
the Chief Counsel for Regulation of the Department of Commerce has 
certified to the Chief Counsel for Advocacy of the Small Business 
Administration that this proposed rule, if adopted, would not have a 
significant economic impact on a substantial number of small entities. 
The Navy is the sole entity that would be subject to the requirements 
in these proposed regulations, and the Navy is not a small governmental 
jurisdiction, small organization, or small business, as defined by the 
RFA. Because of this certification, a regulatory flexibility analysis 
is not required and none has been prepared.
    This proposed rule does not contain a collection-of-information 
requirement subject to the provisions of the Paperwork Reduction Act 
(PRA) because the applicant is a Federal agency.

    Dated: January 5, 2023.
Samuel D. Rauch, III,
Deputy Assistant Administrator for Regulatory Programs, National Marine 
Fisheries Service.

List of Subjects in 50 CFR Part 217

    Administrative practice and procedure, Alaska, Endangered and 
threatened species, Exports, Fish, Fisheries, Fishing, Imports, 
Indians, Labeling, Marine mammals, Oil and gas exploration, Penalties, 
Reporting and recordkeeping requirements, Seafood, Transportation, 
Wildlife.

    For reasons set forth in the preamble, 50 CFR part 217 is proposed 
to be amended as follows:

PART 217--REGULATIONS GOVERNING THE TAKE OF MARINE MAMMALS 
INCIDENTAL TO SPECIFIED ACTIVITIES

0
1. The authority citation for part 217 continues to read as follows:

    Authority:  16 U.S.C. 1361 et seq., unless otherwise noted.

0
2. Add Subpart N to part 217 to read as follows:

Subpart N--Taking and Importing Marine Mammals Incidental to U.S. 
Navy Construction at Portsmouth Naval Shipyard, Kittery, Maine

Sec.
217.130 Specified activity and geographical region.
217.131 Effective dates.
217.132 Permissible methods of taking.
217.133 Prohibitions.
217.134 Mitigation requirements.
217.135 Requirements for monitoring and reporting.
217.136 Letters of Authorization.
217.137 Renewals and modifications of Letters of Authorization.
217.138 [Reserved]
217.139 [Reserved]


Sec.  217.130  Specified activity and geographical region.

    (a) Regulations in this subpart apply only to taking of marine 
mammals by the U.S. Navy (Navy) and those persons it authorizes or 
funds to conduct activities that occurs incidental to construction 
activities related to the multifunctional expansion and modification of 
Dry Dock 1 in the areas outlined in paragraph (b) of this section.
    (b) The taking of marine mammals by the Navy may be authorized in a 
Letter of Authorization (LOA) only if it occurs at Portsmouth Naval 
Shipyard, Kittery, Maine.


Sec.  217.131  Effective dates.

    Regulations in this subpart are effective for a period of five 
years from the date of issuance.


Sec.  217.132  Permissible methods of taking.

    Under an LOA issued pursuant to Sec.  216.106 of this chapter and 
Sec.  217.136, the Holder of the LOA (hereinafter ``Navy'') may 
incidentally, but not intentionally, take marine mammals within the 
area described in Sec.  217.130(b) by harassment associated with 
construction activities related to the multifunctional expansion and 
modification of Dry Dock 1, provided the activity is in compliance with 
all terms, conditions, and requirements of the regulations in this 
subpart and the applicable LOA.


Sec.  217.133  Prohibitions.

    (a) Except for the takings contemplated in Sec.  217.1322 and 
authorized by a LOA issued under Sec.  216.106 of this chapter and 
Sec.  217.136, it is unlawful for any person to do any of the following 
in connection with the activities described in Sec.  217.130:
    (1) Violate, or fail to comply with, the terms, conditions, and 
requirements of this subpart or a LOA issued under Sec.  216.106 of 
this chapter and Sec.  217.136;
    (2) Take any marine mammal not specified in such LOA;
    (3) Take any marine mammal specified in such LOA in any manner 
other than as specified;
    (4) Take a marine mammal specified in such LOA if NMFS determines 
such taking results in more than a negligible impact on the species or 
stocks of such marine mammal; or
    (5) Take a marine mammal specified in such LOA after NMFS 
determines such taking results in an unmitigable adverse impact on the 
species or stock of such marine mammal for taking for subsistence uses.
    (b) [Reserved]


Sec.  217.134  Mitigation requirements.

    (a) When conducting the activities identified in Sec.  217.130(a), 
the mitigation measures contained in this subpart and any LOA issued 
under Sec.  216.106 of this chapter and Sec.  217.136 must be 
implemented. These mitigation measures include:
    (1) A copy of any issued LOA must be in the possession of the Navy, 
its designees, and work crew personnel operating under the authority of 
the issued LOA at all times that activities subject to this LOA are 
being conducted.

[[Page 3193]]

    (2) Should environmental conditions deteriorate such that marine 
mammals within the entire shutdown zone would not be visible (e.g., 
fog, heavy rain, night), the Navy shall delay pile driving and drilling 
until observers are confident marine mammals within the shutdown zone 
could be detected.
    (3) The Navy must ensure that construction supervisors and crews, 
the monitoring team, and relevant Navy staff are trained prior to the 
start of construction activity subject to this rule, so that 
responsibilities, communication procedures, monitoring protocols, and 
operational procedures are clearly understood. New personnel joining 
during the project will be trained prior to commencing work.
    (4) The Navy, construction supervisors and crews, protected species 
observers (observers), and relevant Navy staff must avoid direct 
physical interaction with marine mammals during construction activity. 
If a marine mammal comes within 10 m of such activity, operations will 
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.
    (5) For all pile driving and drilling activities, the Navy must 
implement shutdown zones with radial distances as identified in a LOA 
issued under Sec.  216.106 of this chapter and Sec.  217.136. If a 
marine mammal comes within or approaches the shutdown zone, such 
operations must cease.
    (6) The Navy must monitor the project area to the maximum extent 
possible based on the required number of protected species observers 
(PSOs), required monitoring locations, and environmental conditions as 
described in the NMFS-approved Marine Mammal Monitoring Plan.
    (7) Monitoring must take place from 30 minutes prior to initiation 
of pile driving or drilling activity (i.e., pre-start clearance 
monitoring) through 30 minutes post-completion of pile driving or 
drilling activity. Pre-activity monitoring must be conducted for 30 
minutes to ensure that the shutdown zone is clear of marine mammals, 
and pile driving or drilling may commence when PSOs have declared the 
shutdown zone clear of marine mammals. Monitoring must occur throughout 
the time required to drive/drill a pile. If work ceases for more than 
30 minutes, the pre-activity monitoring of the shutdown zones must 
commence. A determination that the shutdown zone is clear must be made 
during a period of good visibility (i.e., the entire shutdown zone and 
surrounding waters must be visible to the naked eye).
    (8) If a marine mammal enters a shutdown zone, all pile driving or 
drilling activities at that location must be halted. In the event of a 
delay or shutdown of activity resulting from marine mammals in the 
shutdown zone, animals must be allowed to remain in the shutdown zone 
(i.e., must leave of their own volition) and their behavior must be 
monitored and documented. If a marine mammal is observed within the 
shutdown zone, pile driving or drilling activities may not commence or 
resume until at least one of the following conditions has been met:
    (i) The animal has been observed exiting the shutdown zone;
    (ii) The animal is thought to have exited the shutdown zone based 
on a determination of its course, speed, and movement relative to the 
pile driving location; or
    (iii) The shutdown zone has been clear from any additional 
sightings for fifteen minutes.
    (9) The Navy must conduct monitoring to include the entire region 
of influence, which includes the area within the Level A and Level B 
harassment zones with radial distances as identified in a LOA issued 
under Sec.  216.106 of this chapter and Sec.  217.136.
    (10) The Navy must use soft start techniques when impact pile 
driving. Soft start requires contractors to provide an initial set of 
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.
    (11) The Navy must install a bubble curtain across the entrance 
openings during cluster drill and hydraulic rock hammering activities. 
The bubble curtain must adhere to the following restrictions:
    (i) The bubble curtain must distribute air bubbles around 100 
percent of the piling circumference for the full depth of the water 
column;
    (ii) The lowest bubble ring must be in contact with the substrate 
for the full circumference of the ring, and the weights attached to the 
bottom ring shall ensure 100 percent substrate contact. No parts of the 
ring or other objects shall prevent full substrate contact; and
    (iii) Air flow to the bubblers must be balanced around the 
circumference of the pile.
    (iv) The bubble curtain may be discontinued for certain activities 
should the results of hydroacoustic recordings inside the bubble 
curtain show that the source levels from those activities do not result 
in the Level A harassment thresholds being achieved across the entire 
region of influence, upon review of the data by NMFS.
    (12) Pile driving and drilling activity must be halted upon 
observation of either a species entering or within the harassment zone, 
for which incidental take is not authorized, or a species for which 
incidental take has been authorized but the authorized number of takes 
has been met.
    (b) [Reserved]


Sec.  217.135  Requirements for monitoring and reporting.

    (a) The Navy must submit a Marine Mammal Monitoring Plan to NMFS 
for approval in advance of construction. Marine mammal monitoring must 
be conducted in accordance with the conditions in this section and the 
Marine Mammal Monitoring Plan.
    (b) Monitoring must be conducted by qualified PSOs in accordance 
with the following conditions:
    (1) PSOs must be independent (i.e., not construction personnel) and 
have no other assigned tasks during monitoring periods.
    (2) At least one PSO must have prior experience performing the 
duties of a PSO during construction activity pursuant to a NMFS-issued 
incidental take authorization.
    (3) Other PSOs may substitute relevant experience, education 
(degree in biological science or related field), or training for prior 
experience performing the duties of a PSO during construction activity 
pursuant to a NMFS-issued incidental take authorization.
    (4) One PSO must be designated as lead PSO or monitoring 
coordinator. The lead PSO must have prior experience performing the 
duties of a PSO during construction activity pursuant to a NMFS-issued 
incidental take authorization.
    (5) PSOs must be approved by NMFS prior to beginning any activity 
subject to this LOA.
    (c) For all pile driving activities, a minimum of three PSOs must 
be stationed on boats, docks, or piers sufficient to monitor the 
harassment and shutdown zones, and as described in the Marine Mammal 
Monitoring Plan.
    (d) PSOs must record all observations of marine mammals, regardless 
of distance from the pile/hole being driven/drilled, as well as 
additional data indicated in the reporting requirements.

[[Page 3194]]

    (e) The shutdown/monitoring zones may be modified with NMFS' 
approval following NMFS' acceptance of an acoustic monitoring report.
    (f) The Navy must submit a draft monitoring report to NMFS within 
90 work days of the completion of required monitoring for each portion 
of the project as well as a comprehensive summary report at the end of 
the project. The report will detail the monitoring protocol and 
summarize the data recorded during monitoring. Final annual reports 
(each portion of the project and comprehensive) 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 must be considered final. If 
comments are received, a final report addressing NMFS comments must be 
submitted within 30 days after receipt of comments. The reports must at 
minimum contain the informational elements described as follows (as 
well as any additional information described in the Marine Mammal 
Monitoring Plan), including:
    (1) Dates and times (begin and end) of all marine mammal 
monitoring.
    (2) Construction activities occurring during each daily observation 
period, including how many and what type of piles were driven or 
drilled and by what method (i.e., impact, vibratory, rotary drilling, 
rock hammering, mono- or cluster- down-the-hole (DTH)), the total 
duration of driving time for each pile/hole (vibratory driving, rotary 
drilling) and number of strikes for each pile/hole (impact driving, 
hydraulic rock hammering), and for DTH excavation, the duration of 
operation for both impulsive and non-pulse components as well as the 
strike rate.
    (3) Environmental conditions during monitoring periods (at 
beginning and end of observer 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 (if less 
than the harassment zone distance);
    (4) Upon observation of a marine mammal, the following information:
    (i) PSO who sighted the animal and observer location, as well as 
the activity at the time of the sighting;
    (ii) Time of sighting;
    (iii) 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;
    (iv) Distances and bearings of each marine mammal observed in 
relation to the pile being driven or drilled for each sighting (if pile 
driving or drilling was occurring at time of sighting).
    (v) Estimated number of animals (min/max/best);
    (vi) Estimated number of animals by cohort (adults, juveniles, 
neonates, group composition etc.);
    (vii) Animal's closest point of approach and estimated time spent 
within the harassment zone; and
    (viii) 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);
    (ix) Number of marine mammals detected within the harassment zones, 
by species;
    (x) Detailed information about any implementation of any mitigation 
(e.g., shutdowns and delays), a description of specific actions that 
ensued, and resulting changes in the behavior of the animal, if any; 
and
    (xi) All PSO datasheets and/or raw sightings data.
    (g) The Navy must conduct hydroacoustic data collection (sound 
source verification and propagation loss) in accordance with a 
hydroacoustic monitoring plan that must be approved by NMFS in advance 
of construction. This includes measurements from 10 piles/holes during 
the rotary drilling of 126-inch and 84-inch shafts, and DTH cluster 
drilling of 108-inch, 84-inch, and 72-inch shafts. The Navy must report 
the hydroacoustic data collected as required by a LOA issued under 
Sec.  216.106 of this chapter and Sec.  217.136 and as described in the 
Acoustic Monitoring Plan, which at a minimum, must include:
    (1) Hydrophone equipment and methods: recording device, sampling 
rate, distance (m) from the pile where recordings were made; depth of 
water and recording device(s);
    (2) 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;
    (3) 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;
    (4) 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);
    (5) 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);
    (6) One-third octave band spectrum and power spectral density plot; 
and
    (7) General Daily Site Conditions, including the date and time of 
activities, the water conditions (e.g., sea state, tidal state), and 
the weather conditions (e.g., percent cover, visibility).
    (h) All draft and final monitoring reports must be submitted to 
[email protected] and [email protected].
    (i) In the event that personnel involved in the construction 
activities discover an injured or dead marine mammal, the Navy must 
report the incident to NMFS Office of Protected Resources (OPR), and to 
the Greater Atlantic Region New England/Mid-Atlantic Stranding 
Coordinator, 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 and the 
LOA issued under Sec.  216.106 of this chapter and Sec.  217.136. The 
Navy will not resume their activities until notified by NMFS. The 
report must include the following information:
    (1) Time, date, and location (latitude/longitude) of the first 
discovery (and updated location information if known and applicable);
    (2) Species identification (if known) or description of the 
animal(s) involved;
    (3) Condition of the animal(s) (including carcass condition if the 
animal is dead);
    (4) Observed behaviors of the animal(s), if alive;
    (5) If available, photographs or video footage of the animal(s); 
and
    (6) General circumstances under which the animal was discovered.


Sec.  217.136  Letters of Authorization.

    (a) To incidentally take marine mammals pursuant to this subpart, 
the Navy must apply for and obtain an LOA.
    (b) An LOA, unless suspended or revoked, may be effective for a 
period of

[[Page 3195]]

time not to exceed the expiration date of these regulations.
    (c) If an LOA expires prior to the expiration date of these 
regulations, the Navy may apply for and obtain a renewal of the LOA.
    (d) In the event of projected changes to the activity or to 
mitigation and monitoring measures required by an LOA, the Navy must 
apply for and obtain a modification of the LOA as described in Sec.  
217.137.
    (e) The LOA will set forth the following information:
    (1) Permissible methods of incidental taking;
    (2) Means of effecting the least practicable adverse impact (i.e., 
mitigation) on the species, its habitat, and on the availability of the 
species for subsistence uses; and
    (3) Requirements for monitoring and reporting.
    (f) Issuance of the LOA will be based on a determination that the 
level of taking will be consistent with the findings made for the total 
taking allowable under these regulations.
    (g) Notice of issuance or denial of an LOA will be published in the 
Federal Register within 30 days of a determination.


Sec.  217.137  Renewals and modifications of Letters of Authorization.

    (a) An LOA issued under Sec.  216.106 of this chapter and Sec.  
217.136 for the activity identified in Sec.  217.130(a) may be renewed 
or modified upon request by the applicant, provided that:
    (1) The proposed specified activity and mitigation, monitoring, and 
reporting measures, as well as the anticipated impacts, are the same as 
those described and analyzed for these regulations; and
    (2) NMFS determines that the mitigation, monitoring, and reporting 
measures required by the previous LOA under these regulations were 
implemented.
    (b) For LOA modification or renewal requests by the applicant that 
include changes to the activity or the mitigation, monitoring, or 
reporting that do not change the findings made for the regulations or 
result in no more than a minor change in the total estimated number of 
takes (or distribution by species or years), NMFS may publish a notice 
of proposed LOA in the Federal Register, including the associated 
analysis of the change, and solicit public comment before issuing the 
LOA.
    (c) A LOA issued under Sec.  216.106 of this chapter and Sec.  
217.136 for the activity identified in Sec.  217.130(a) may be modified 
by NMFS under the following circumstances:
    (1) NMFS may modify (including augment) the existing mitigation, 
monitoring, or reporting measures (after consulting with Navy regarding 
the practicability of the modifications) if doing so creates a 
reasonable likelihood of more effectively accomplishing the goals of 
the mitigation and monitoring set forth in the preamble for these 
regulations;
    (i) Possible sources of data that could contribute to the decision 
to modify the mitigation, monitoring, or reporting measures in a LOA:
    (A) Results from Navy's monitoring from previous years;
    (B) Results from other marine mammal and/or sound research or 
studies; and
    (C) Any information that reveals marine mammals may have been taken 
in a manner, extent or number not authorized by these regulations or 
subsequent LOAs; and
    (ii) If, through adaptive management, the modifications to the 
mitigation, monitoring, or reporting measures are substantial, NMFS 
will publish a notice of proposed LOA in the Federal Register and 
solicit public comment;
    (2) If NMFS determines that an emergency exists that poses a 
significant risk to the well-being of the species or stocks of marine 
mammals specified in a LOA issued pursuant to Sec.  216.106 of this 
chapter and Sec.  217.136, a LOA may be modified without prior public 
notice or opportunity for public comment. Notification would be 
published in the Federal Register within 30 days of the action.


Sec.  217.138-217.139  [Reserved]

[FR Doc. 2023-00332 Filed 1-17-23; 8:45 am]
BILLING CODE 3510-22-P