Proposed Rule2023-00332
Taking and Importing Marine Mammals; Taking Marine Mammals Incidental to U.S. Navy Construction at Portsmouth Naval Shipyard, Kittery, Maine
Primary source
Metadata and text below are from the Federal Register, a public-domain U.S. government work. Always verify the official published version before relying on it for any legal matter.
Published
January 18, 2023
Issuing agencies
Commerce DepartmentNational Oceanic and Atmospheric Administration
Abstract
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.
Full Text
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<title>Federal Register, Volume 88 Issue 11 (Wednesday, January 18, 2023)</title>
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[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 [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2023-00332]
[[Page 3145]]
Vol. 88
Wednesday,
No. 11
January 18, 2023
Part III
Department of Commerce
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National Oceanic and Atmospheric Administration
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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]]
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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.
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SUMMARY: NMFS has received a request from the U.S. Navy (Navy) for
authorization to take marine mammals incidental to construction 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: <a href="https://www.fisheries.noaa.gov/action/incidental-take-authorization-us-navy-construction-portsmouth-naval-shipyard-kittery-maine-0">https://www.fisheries.noaa.gov/action/incidental-take-authorization-us-navy-construction-portsmouth-naval-shipyard-kittery-maine-0</a>. 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 <a href="http://www.regulations.gov">www.regulations.gov</a> 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
<a href="http://www.regulations.gov">www.regulations.gov</a> 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, <a href="/cdn-cgi/l/email-protection#dd94898df3a9a4aeb2b3f3b0b2b2afb89db3b2bcbcf3bab2ab"><span class="__cf_email__" data-cfemail="6d24393d4319141e0203430002021f082d03020c0c430a021b">[email protected]</span></a>, (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:
<bullet> Required monitoring of the in-water construction areas to
detect the presence of marine mammals before beginning in-water
construction activities;
<bullet> Shutdown of in-water construction activities under certain
circumstances to avoid injury of marine mammals;
<bullet> 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
<bullet> 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: <a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities">https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities</a>)
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
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[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; <a href="http://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments">www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments</a>) and more general
information about these species (e.g., physical and behavioral
descriptions) may be found on NMFS' website (<a href="https://www.fisheries.noaa.gov/find-species">https://www.fisheries.noaa.gov/find-species</a>).
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:
<a href="http://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments">www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments</a>).
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: <a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments">https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments</a> 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: <a href="https://www.fisheries.noaa.gov/new-england-mid-atlantic/marine-life-distress/2018-2020-pinniped-unusual-mortality-event-along">https://www.fisheries.noaa.gov/new-england-mid-atlantic/marine-life-distress/2018-2020-pinniped-unusual-mortality-event-along</a>.
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: <a href="https://www.fisheries.noaa.gov/2022-pinniped-unusual-mortality-event-along-maine-coast">https://www.fisheries.noaa.gov/2022-pinniped-unusual-mortality-event-along-maine-coast</a>.
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
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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
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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
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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
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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 <a href="https://media.fisheries.noaa.gov/2022-11/PUBLIC%20DTH%20Basic%20Guidance_November%202022.pdf">https://media.fisheries.noaa.gov/2022-11/PUBLIC%20DTH%20Basic%20Guidance_November%202022.pdf</a>; 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:
<a href="http://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance">www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance</a>.
[[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]
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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)
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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.
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\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
[…truncated; see source link]Indexed from Federal Register on January 18, 2023.
This is legal information, not legal advice. Laws vary by jurisdiction and change frequently. Always verify current law with official sources and consult a licensed attorney in your jurisdiction for advice on your specific situation.