[Federal Register Volume 86, Number 108 (Tuesday, June 8, 2021)]
[Notices]
[Pages 30418-30434]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-11983]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

[RTID 0648-XB146]


Takes of Marine Mammals Incidental to Specified Activities; 
Taking Marine Mammals Incidental to Portsmouth Naval Shipyard Dry Dock 
1 Modification and Expansion

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

ACTION: Notice; issuance of incidental harassment authorization.

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SUMMARY: In accordance with the regulations implementing the Marine 
Mammal Protection Act (MMPA) as amended, notification is hereby given 
that NMFS has issued an IHA to the U.S. Navy (Navy) to incidentally 
harass, by Level B and Level A harassment, marine mammals incidental to 
Portsmouth Naval Shipyard (PNSY) Dry Dock 1 (DD1) modification and 
expansion in Kittery, Maine.

DATES: This authorization is effective from June 2, 2021 through June 
1, 2022.

FOR FURTHER INFORMATION CONTACT: Carter Esch, Office of Protected 
Resources, NMFS, (301) 427-8421. Electronic copies of the application 
and supporting documents, as well as a list of the references cited in 
this document, may be obtained online at: https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act. In case of problems accessing these 
documents, please call the contact listed above.

SUPPLEMENTARY INFORMATION:

Background

    The MMPA prohibits the ``take'' of marine mammals, with certain 
exceptions. Sections 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361 
et seq.) direct the Secretary of Commerce (as delegated to NMFS) to 
allow, upon request, the incidental, but not intentional, taking of 
small numbers of marine mammals by U.S. citizens who engage in a 
specified activity (other than commercial fishing) within a specified 
geographical region if certain findings are made and either regulations 
are

[[Page 30419]]

issued or, if the taking is limited to harassment, a notice of a 
proposed incidental take authorization may be provided to the public 
for review.
    Authorization for incidental takings shall be granted if NMFS finds 
that the taking will have a negligible impact on the species or 
stock(s) and will not have an unmitigable adverse impact on the 
availability of the species or stock(s) for taking for subsistence uses 
(where relevant). Further, NMFS must prescribe the permissible methods 
of taking and other means of effecting the least practicable adverse 
impact on the affected species or stocks and their habitat, paying 
particular attention to rookeries, mating grounds, and areas of similar 
significance, and on the availability of such species or stocks for 
taking for certain subsistence uses (referred to here as 
``mitigation''). Monitoring and reporting of such takings are also 
required. The meaning of key terms such as ``take,'' ``harassment,'' 
and ``negligible impact'' can be found in section 3 of the MMPA (16 
U.S.C. 1362 and the agency's regulations at 50 CFR 216.103.

Summary of Request

    On October 22, 2020, NMFS received a request from the Navy for an 
IHA to take marine mammals incidental to modification and expansion of 
DD1 at PNSY in Kittery, Maine. The Navy submitted revised versions of 
the application on December 30, 2020, and January 19 and February 11, 
2021. The application was deemed adequate and complete on February 19, 
2021. The Navy's request is for take of a small number of harbor 
porpoises, harbor seals, gray seals, harp seals, and hooded seals by 
Level B harassment and Level A harassment for a subset of these 
species. Neither the Navy nor NMFS expects serious injury or mortality 
to result from this activity; therefore, an IHA is appropriate.
    NMFS previously issued three IHAs to the Navy for waterfront 
improvement work, in 2016 (81 FR 85525; November 28, 2016), 2018 (83 FR 
3318; January 24, 2018), 2019 (84 FR 24476, May 28, 2019), and a 
renewal of the 2019 IHA (86 FR 14598; March 17, 2021). As required, the 
applicant provided monitoring reports (available at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities) which confirm that the 
applicant has implemented the required mitigation and monitoring, and 
which also shows that no impacts of a scale or nature not previously 
analyzed or authorized have occurred as a result of the activities 
conducted. This IHA covers the second year of a larger five-year 
project, for which the Navy also intends to request take authorization 
for subsequent dock modification and expansion at the PNSY.

Description of the Specified Activity

    As part of its overall objective to modernize and maximize dry dock 
capabilities for performing current and future missions efficiently and 
with maximum flexibility, the Navy plans to modify and expand DD1 at 
the PNSY by constructing two new dry docking positions capable of 
servicing Virginia class submarines within the super flood basin of the 
dry dock. The in-water portion of the dock modification and expansion, 
which will occur within and at the boundaries of the super flood basin, 
includes: Construction of the west closure wall, construction of 
entrance structure closure walls, and bedrock excavation. Construction 
activities include in-water impact pile driving, vibratory pile driving 
and removal, rock drilling, and underwater blasting. Underwater sounds 
produced by these activities may result in Level B harassment and Level 
A harassment of marine mammal species.
    In-water construction activities are expected to occur between June 
2021 and June 2022, with an estimated total of 29 days for pile driving 
and pile removal, 130 days for drilling of blast charge holes, and 130 
days of blasting for bedrock excavation, for a total of 289 
construction days. Some of these activities will occur on the same day, 
resulting in 159 total construction days over 12 months. However, as a 
conservative measure, construction days are accounted for as 
consecutive rather than concurrent activities in take estimates (see 
Estimated Take section). All in-water construction work will be limited 
to daylight hours, with the exception of pre-dawn (beginning no earlier 
than 3:00 a.m.) drilling of blast charge holes; drilling will not occur 
from sunset to pre-dawn. The daily construction timeframe for blasting 
will begin no sooner than 30 minutes after sunrise to allow for initial 
marine mammal monitoring to take place and will end at least 60 minutes 
before sunset to allow for post-activity monitoring.
    A summary of in-water pile driving activity is provided in Table 1. 
In addition, a total of 1,580, 4.5-inch blast charge holes will be 
drilled at a rate of 12 holes per day over 130 days. The Navy 
anticipates one to two blast events per day, with a maximum of 6 blast 
events per week; a total of 150 blast events will occur over 130 days.

                                                  Table 1--Summary of In-Water Pile Driving Activities
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                  Pile size
             Pile purpose                      Pile type            (inch)       Pile drive method           Total piles         Piles/day    Work days
--------------------------------------------------------------------------------------------------------------------------------------------------------
West closure wall template...........  Steel pipe..............           30  Vibratory..............  13 installed...........            3            5
                                                                                                       13 removed.............            3            5
West closure wall construction.......  Flat-webbed steel sheet.           18  Vibratory..............  160....................           12           13
                                                                              Impact.................
Entrance structure temporary guide     Steel pipe..............           30  Vibratory..............  12.....................            8            2
 dolphin removal.
Entrance structure closure wall        Steel sheet.............           28  Vibratory..............  44.....................           12            4
 construction.
                                                                              Impact.................
                                                                -------------                         --------------------------------------------------
    Total............................  ........................  ...........  .......................  242....................  ...........           29
--------------------------------------------------------------------------------------------------------------------------------------------------------

    Construction activities will occur at the PNSY in Kittery, Maine. 
Please see Figures 1-1 to 1-6 in the Navy's IHA application for 
detailed maps of the project area and super flood basin. A detailed 
description of the planned modification and expansion of DD1 is 
provided in the Federal Register notice for the proposed IHA (86 FR 
18244; April 8, 2021). Since that time, no changes have been made to 
the planned activities. Therefore, a detailed

[[Page 30420]]

description is not provided here. Please refer to that Federal Register 
notice and the original proposed IHA documents referenced therein for a 
detailed description of the specified activity.

Comments and Responses

    A notice of NMFS' proposal to issue an IHA to the Navy was 
published in the Federal Register on April 8, 2021 (86 FR 18244). That 
notice described, in detail, the Navy's activity, the marine mammal 
species that may be affected by the activity, and the anticipated 
effects on marine mammals. During the 30-day public comment period, 
NMFS received comments from the Marine Mammal Commission (Commission). 
For full details of the comments, please see the Commission's letter, 
which is available online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities#active-authorizations. A summary of the Commission's 
recommendations as well as NMFS' responses is below.
    Comment 1: As a result of its belief that NMFS did not provide the 
public with an adequate basis for review of NMFS' proposed action, due 
to what it asserts are errors in the notice of the proposed 
authorization, the Commission recommends that NMFS either deny the 
proposed incidental harassment authorization or publish a revised 
Federal Register notice and draft authorization with another 30-day 
comment period.
    Response: NMFS does not agree with the Commission and does not 
adopt the recommendation. Although the initial Federal Register notice 
and proposed authorization contained certain errors and omissions, 
which have been addressed in this notice and authorization according to 
the Commission's recommendations, the description of the specified 
activity and analysis of potential acoustic impacts on marine mammals 
in the vicinity of the project area in the notice of the proposed 
authorization (86 FR 18422; April 8, 2021) provided sufficient 
information upon which to determine whether or not the activities would 
have a negligible impact on the species or stocks for which take is 
likely to occur, and on which the public had an opportunity to comment. 
The information utilized in take estimation (i.e., source levels, 
thresholds, densities, and number of construction days for each 
specified activity) has largely been retained from the proposed to the 
final authorization, with the exception of revised source levels for 
impact pile driving of an 18-inch flat-webbed sheet pile (which reduced 
the harassment zone sizes and take estimates for gray and harbor 
seals). The Commission noted that the thresholds associated with slight 
lung injury and mortality were incorrectly specified in the notice of 
the proposed IHA. However, the distances to the isopleths for onset of 
and 50 percent probability of gastrointestinal tract injury, and the 
resulting estimate of zero take for harbor porpoises and phocids, 
provided accurate information regarding the potential for this type of 
non-auditory injury. The distances to thresholds associated with 
gastrointestinal injury (harbor porpoises, 26 meters (m); phocids, 26 
m), slight lung injury (harbor porpoises, 48 meters; phocids, 34 m) and 
mortality (harbor porpoises, 21 m; phocids, 18 m) calculated for the 
City of Juneau's Statter Harbor Project (see 84 FR 11066; March 25, 
2019) are similar to each other in magnitude. The distances to slight 
lung injury and mortality thresholds are not expected to be 
substantially different for blasting at PNSY than those calculated for 
Statter Harbor, and would likely be within tens of meters from those 
estimated here for onset of and 50 percent probability of 
gastrointestinal tract injury. All of these zones would be smaller than 
the Level A harassment zones for harbor porpoises and phocids, and 
would be encompassed by the large shutdown zone for blasting at DD1. 
The mitigation requirements for blasting events, including the use of 
stemmed charges, installation of a double bubble curtain across 
openings to the super flood basin in which blasting will occur, and 
implementation of shutdown procedures, are sufficiently protective to 
minimize the potential for non-auditory injury such that the potential 
for non-auditory injury is considered discountable. No mortality is 
anticipated or authorized for these activities. Per the Commission's 
recommendations, additional mitigation and monitoring requirements for 
blasting have been incorporated into the issued authorization.
    The majority of the Commission's comments pertained to errors or 
inconsistencies that have been addressed in this notice and the final 
authorization. NMFS' small numbers finding and negligible impact 
determination were not affected by the changes from the proposed to the 
final authorization; therefore, NMFS is not republishing a notice of 
the proposed authorization.
    Comment 2: The Commission recommends that NMFS return the IHA 
application to the Navy as incomplete and refrain from processing 
future authorization applications until the Commission's perceived 
issues are resolved.
    Response: NMFS appreciates the Commission's concern but will 
consider any future requests for incidental take authorization from the 
Navy according to the requirements of the MMPA.

Changes From the Proposed IHA to the Final IHA

    The following corrections and additions have been incorporated into 
this notice and/or the issued IHA:
     Corrected the reference for the 28-inch Z-shaped sheet 
pile source level (NAVFAC 2020; Table 6);
     Revised source levels for impact pile driving of 18-inch 
flat-webbed sheet piles, as well as all associated acoustic analyses 
and take estimation;
     Included a description of transmission loss modeling, as 
well as the coefficients used to estimate Level B harassment zones for 
construction activities;
     Included the input parameters used to estimate Level A 
harassment zones for pile driving and removal, and blast-charge hole 
drilling (Table 8);
     Corrected distance to the Level B harassment isopleth for 
removal of 30-inch steel pipe piles to 13.6 kilometers (km) from 46 km 
(Table 8);
     Corrected typographical errors specifying ensonified zones 
in Tables 8 and 9;
     Included ranges to peak SPL thresholds for PTS for 
blasting events as a footnote of Table 9;
     Refined identification of the specific activities to which 
take is attributed (Table 11);
     Corrected take estimate for harbor porpoises (reduced from 
6 to 4) to align with the IHA application, and adjusted take estimates 
for impact pile driving of 18-inch flat-webbed sheet piles based on 
revised source levels (Table 11);
     Added additional mitigation requirements for blasting, 
including (1) requiring stemmed charges, (2) restricting blasting to a 
time period at least 30 minutes after sunrise and one hour before 
sunset, (3) requiring monitoring to occur for at least one hour after 
blasting activities cease, (4) requiring that the Navy notify NMFS and 
the Greater Atlantic Regional Stranding Coordinator or local stranding 
network at least 24 hours prior to commencing a blasting event and 
within 24 hours after a blasting event ceases (if occurring on 
consecutive days, the Navy can provide notice of how long blasting is 
scheduled to last and when it has been completed), and (5) requiring 
that the Navy immediately report any injured or dead marine mammal to 
the

[[Page 30421]]

Greater Atlantic Regional Stranding Coordinator or local stranding 
network and follow any instructions provided by the Stranding 
Coordinator or stranding network;
     Clarified the number and potential locations of Protected 
Species Observers (PSOs);
     Clarified that pile driving/removal must only occur during 
daylight hours;
     Clarified in this notice that 10, 18-inch flat-webbed 
piles will be acoustically monitored during vibratory and impact pile 
driving, and 4, 30-inch steel piles will be monitored during vibratory 
pile driving, as was included in the draft IHA;
     Added hydroacoustic monitoring plan, which can be accessed 
at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities#active-authorizations;
     Corrected contact information and requirements for 
reporting a dead or injured marine mammal to provide consistency 
between this notice and the IHA;
     Clarified that the IHA condition 4(e) applies to all 
activities; and

Description of Marine Mammals in the Area of Specified Activities

    Sections 3 and 4 of the application summarize available information 
regarding status and trends, distribution and habitat preferences, and 
behavior and life history, of the potentially affected species. 
Additional information regarding population trends and threats may be 
found in NMFS' Stock Assessment Reports (SARs; https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments) and more general information about these species 
(e.g., physical and behavioral descriptions) may be found on NMFS' 
website: (https://www.fisheries.noaa.gov/find-species).
    Table 2 lists the five marine mammal species, including one 
cetacean and four pinnipeds, with the potential to occur in the area of 
the specified activity and for which take is authorized for this 
action, and summarizes information related to the population or stock, 
including regulatory status under the MMPA and ESA and potential 
biological removal (PBR), where known. For taxonomy, NMFS follows 
Committee on Taxonomy (2020). PBR is defined by the MMPA as the maximum 
number of animals, not including natural mortalities, that may be 
removed from a marine mammal stock while allowing that stock to reach 
or maintain its optimum sustainable population (as described in NMFS' 
SARs). While no mortality is anticipated or authorized here, PBR and 
annual serious injury and mortality from anthropogenic sources are 
included here as gross indicators of the status of the species and 
other threats.
    Marine mammal abundance estimates presented in this document 
represent the total number of individuals that make up a given stock or 
the total number estimated within a particular study or survey area. 
NMFS' stock abundance estimates for most species represent the total 
estimate of individuals within the geographic area, if known, that 
comprises that stock. For some species, this geographic area may extend 
beyond U.S. waters. All managed stocks in this region are assessed in 
NMFS' U.S. Atlantic Marine Mammal SARs. All values presented in Table 2 
are the most recent available at the time of publication and are 
available in the final 2019 SARs (Hayes et al., 2020) and draft 2020 
SARs, available online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/draft-marine-mammal-stock-assessment-reports).

                                         Table 2--Marine Mammals With Potential Presence Within the Project Area
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                                                                                         ESA/MMPA status;    Stock abundance  (CV,
             Common name                  Scientific name               Stock             strategic (Y/N)      Nmin, most recent       PBR     Annual M/
                                                                                                \1\          abundance survey) \2\               SI \3\
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                         Order Cetartiodactyla--Cetacea--Superfamily Odontoceti (toothed whales)
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Family Phocoenidae (porpoises):
    Harbor porpoise.................  Phocoena phocoena......  Gulf of Maine/Bay of     -; N                95,543 (0.31; 74,034;         851        217
                                                                Fundy.                                       2016).
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                         Order Carnivora--Superfamily Pinnipedia
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Family Phocidae (earless seals):
    Harbor seal.....................  Phoca vitulina.........  Western North Atlantic.  -; N                75,834 (0.15, 66,884;       2,006        350
                                                                                                             2012).
    Gray seal.......................  Halichoerus grypus.....  Western North Atlantic.  -; N                27,131 \4\ (0.19;           1,389      4,729
                                                                                                             23,158; 2016).
    Harp seal.......................  Pagophilus               Western North Atlantic.  -; N                Unknown (NA, NA)......        unk    232,422
                                       groenlandicus.
    Hooded seal.....................  Cystophora cristata....  Western North Atlantic.  -; N                Unknown (NA, NA)......        unk      1,680
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\1\ Endangered Species Act (ESA) status: Endangered (E), Threatened (T)/MMPA status: Depleted (D). A dash (-) indicates that the species is not listed
  under the ESA or designated as depleted under the MMPA. Under the MMPA, a strategic stock is one for which the level of direct human-caused mortality
  exceeds PBR or which is determined to be declining and likely to be listed under the ESA within the foreseeable future. Any species or stock listed
  under the ESA is automatically designated under the MMPA as depleted and as a strategic stock.
\2\ NMFS marine mammal stock assessment reports online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessment-reports-region#reports. CV is coefficient of variation; Nmin is the minimum estimate of stock abundance.
\3\ These values, found in NMFS' SARs, represent annual levels of human-caused mortality plus serious injury from all sources combined (e.g., commercial
  fisheries, ship strike). Annual M/SI often cannot be determined precisely and is in some cases presented as a minimum value or range. A CV associated
  with estimated mortality due to commercial fisheries is presented in some cases.
\4\ NMFS stock abundance estimate applies to U.S. population only, actual stock abundance is approximately 451,431. The PBR value presented is in
  relation to the U.S. population, whereas the annual M/SI value is for the entire stock.

    Detailed descriptions of the species likely to be affected by the 
Navy's activities, including brief introductions to the species and 
relevant stocks as well as available information regarding population 
trends and threats, and information regarding local occurrence were 
provided in the notice of the proposed IHA (86 FR 18244; April 8, 
2021). Since that time, NMFS is not aware of any substantive new 
information regarding these species or stocks; therefore, detailed 
descriptions are not provided here. Please refer to that notice for 
descriptions. Please also refer to NMFS' website 
(www.fisheries.noaa.gov/find-species) for generalized species accounts.

Marine Mammal Hearing

    Hearing is the most important sensory modality for marine mammals 
underwater, and exposure to anthropogenic sound can have

[[Page 30422]]

deleterious effects. To appropriately assess the potential effects of 
exposure to sound, it is necessary to understand the frequency ranges 
marine mammals are able to hear. Current data indicate that not all 
marine mammal species have equal hearing capabilities (e.g., Richardson 
et al., 1995; Wartzok and Ketten, 1999; Au and Hastings, 2008). To 
reflect this, Southall et al. (2007) recommended that marine mammals be 
divided into functional hearing groups based on directly measured or 
estimated hearing ranges on the basis of available behavioral response 
data, audiograms derived using auditory evoked potential techniques, 
anatomical modeling, and other data. Note that no direct measurements 
of hearing ability have been successfully completed for mysticetes 
(i.e., low-frequency cetaceans). Subsequently, NMFS (2018) described 
generalized hearing ranges for these marine mammal hearing groups. 
Generalized hearing ranges were chosen based on the approximately 65 
decibel (dB) threshold from the normalized composite audiograms, with 
the exception for lower limits for low-frequency cetaceans where the 
lower bound was deemed to be biologically implausible and the lower 
bound from Southall et al. (2007) retained. Marine mammal hearing 
groups and their associated hearing ranges are provided in Table 3.

                  Table 3--Marine Mammal Hearing Groups
                              [NMFS, 2018]
------------------------------------------------------------------------
            Hearing group                 Generalized hearing range *
------------------------------------------------------------------------
Low-frequency (LF) cetaceans (baleen  7 Hz to 35 kHz.
 whales).
Mid-frequency (MF) cetaceans          150 Hz to 160 kHz.
 (dolphins, toothed whales, beaked
 whales, bottlenose whales).
High-frequency (HF) cetaceans (true   275 Hz to 160 kHz.
 porpoises, Kogia, river dolphins,
 cephalorhynchid, Lagenorhynchus
 cruciger & L. australis).
Phocid pinnipeds (PW) (underwater)    50 Hz to 86 kHz.
 (true seals).
Otariid pinnipeds (OW) (underwater)   60 Hz to 39 kHz.
 (sea lions and fur seals).
------------------------------------------------------------------------
* Represents the generalized hearing range for the entire group as a
  composite (i.e., all species within the group), where individual
  species' hearing ranges are typically not as broad. Generalized
  hearing range chosen based on ~65 dB threshold from normalized
  composite audiogram, with the exception for lower limits for LF
  cetaceans (Southall et al. 2007) and PW pinniped (approximation).

    The pinniped functional hearing group was modified from Southall et 
al. (2007) on the basis of data indicating that phocid species have 
consistently demonstrated an extended frequency range of hearing 
compared to otariids, especially in the higher frequency range 
(Hemil[auml] et al., 2006; Kastelein et al., 2009; Reichmuth and Holt, 
2013).
    For more detail concerning these groups and associated frequency 
ranges, please see NMFS (2018) for a review of available information. 
As mentioned previously, five marine mammal species (one cetacean and 
four pinniped (all phocid) species) have the reasonable potential to 
co-occur with the construction activities. Please refer to Table 2. The 
only cetacean species that may be present, the harbor porpoise, is 
classified as a high-frequency cetacean.

Potential Effects of Specified Activities on Marine Mammals and Their 
Habitat

    The effects of underwater noise from impact pile driving, vibratory 
pile driving and removal, drilling, and blasting activities for the 
Navy's modification and expansion of DD1 have the potential to result 
in Level B harassment (behavioral disturbance, TTS) for marine mammal 
species authorized for take. Level A harassment (injury) in the form of 
PTS may also occur in limited numbers of animals. No other forms of 
Level A harassment would occur, nor would serious injury or mortality. 
The project would not result in permanent impacts to habitats used 
directly by marine mammals, such as haulout sites, but may have 
potential short-term impacts to food sources such as forage fish and 
impacts to the substrate during installation and removal of piles and 
as a result of bedrock removal. The Federal Register notice of the 
proposed IHA (86 FR 18244; April 8, 2021) included a discussion of the 
potential effects to marine mammals and their associated habitat, 
therefore, that information is not repeated here; please refer to the 
notice of proposed IHA for more details.

Estimated Take

    This section provides an estimate of the number of incidental takes 
authorized by the IHA, which informed both NMFS' consideration of 
``small numbers'' and the negligible impact determination.
    Harassment is the only type of take expected to result from these 
activities. Except with respect to certain activities not pertinent 
here, section 3(18) of the MMPA defines ``harassment'' as any act of 
pursuit, torment, or annoyance, which (i) has the potential to injure a 
marine mammal or marine mammal stock in the wild (Level A harassment); 
or (ii) has the potential to disturb a marine mammal or marine mammal 
stock in the wild by causing disruption of behavioral patterns, 
including, but not limited to, migration, breathing, nursing, breeding, 
feeding, or sheltering (Level B harassment).
    Authorized takes would be primarily by Level B behavioral 
harassment, as noise generated from in-water pile driving (vibratory 
and impact), drilling, and blasting has the potential to result in 
disruption of behavioral patterns for individual marine mammals. The 
use of the explosive source (i.e., blasting) for a very short period 
each day has the potential to result in Temporary Threshold Shift 
(TTS), which is another form of Level B harassment. There is also some 
potential for auditory injury (Level A harassment) to result from 
impact pile driving and blasting in the form of Permanent Threshold 
Shift (PTS). The required mitigation and monitoring measures (see 
Mitigation Requirements and Monitoring and Reporting Requirements 
sections) are expected to minimize the severity of such taking to the 
extent practicable.
    The primary relevant mitigation measure to minimize Level A 
harassment is delaying these activities, to the extent practicable, 
when any marine mammal is observed in the Level A harassment zones for 
PTS. While this requirement is expected to minimize take by Level A 
harassment, NMFS is authorizing takes by Level A harassment (in the 
form of PTS) to account for the possibility that marine mammals escape 
observation in the PTS zone and because the shutdown zones (see 
Mitigation Requirements section) are, in most cases, smaller than the 
Level A harassment zones. The distances to thresholds associated with 
the onset of and 50 percent probability of injury to the 
gastrointestinal tract for harbor porpoises (5 meters (m)) and phocids 
(9

[[Page 30423]]

m) are small enough that the mitigation and monitoring measures are 
expected to avoid the potential for such taking. As mentioned 
previously, distances to thresholds for slight lung injury and 
mortality are not modeled here, but are expected to have a similar 
small magnitude and range of values (tens of meters) as those reported 
for the Statter Harbor project (84 FR 11066; March 25, 2019). In 
conjunction with small zone sizes for onset of and 50 percent 
probability of gastrointestinal tract injury and NMFS' expectation that 
zone sizes for slight lung injury will be small, blasting will occur in 
a confined area that allows for effective observation with only one 
entrance to the basin that will be blocked by a bubble curtain during 
blasting events, within a large shutdown zone equivalent to the Level A 
harassment zone for harbor porpoises, all of which make it unlikely 
that these types of non-auditory injuries will occur. Therefore, the 
potential for non-auditory physical injury is considered discountable, 
and any takes by Level A harassment are expected to occur due to PTS.
    As described previously, no mortality is anticipated or authorized 
for these activities. The method by which take is estimated is 
described below.
    Generally speaking, NMFS estimates take by considering: (1) 
Acoustic thresholds above which NMFS believes 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) and the number of days 
of activities. NMFS notes that while these basic factors can contribute 
to a basic calculation to provide an initial prediction of takes, 
additional information that can qualitatively inform take estimates is 
also sometimes available (e.g., previous monitoring results or average 
group size). Below, NMFS describes the factors considered here in more 
detail and presents the authorized take.

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 or experience 
TTS (equated to Level B harassment), or to incur PTS of some degree 
(equated to Level A harassment). Thresholds have also been developed to 
identify the pressure levels above which animals may incur different 
types of tissue damage from exposure to pressure waves from explosive 
detonations.
    Level B Harassment for non-explosive sources--Though significantly 
driven by received level, the onset of behavioral disturbance from 
anthropogenic noise exposure is also informed to varying degrees by 
other factors related to the source (e.g., frequency, predictability, 
duty cycle), the environment (e.g., bathymetry), and the receiving 
animals (hearing, motivation, experience, demography, behavioral 
context) and can be difficult to predict (Southall et al., 2007, 
Ellison et al., 2012). Based on what the available science indicates 
and the practical need to use a threshold based on a factor that is 
both predictable and measurable for most activities, NMFS uses a 
generalized acoustic threshold based on received level to estimate the 
onset of behavioral harassment. NMFS predicts that marine mammals are 
likely to be behaviorally harassed in a manner NMFS considers Level B 
behavioral harassment when exposed to underwater anthropogenic noise 
above received levels of 120 dB re 1 [mu]Pa (rms) for continuous (e.g., 
vibratory pile-driving, drilling) and above 160 dB re 1 [mu]Pa (rms) 
for impulsive and/or intermittent (e.g., impact pile driving) sources.
    The Navy's Portsmouth Naval Shipyard modification and expansion 
project includes the use of continuous, or non-impulsive, (i.e., 
vibratory pile driving and drilling) and impulsive (i.e., impact pile 
driving) sources; therefore, the 120 and 160 dB re 1 [mu]Pa (rms) 
thresholds are appropriate.
    Level A harassment for non-explosive sources--NMFS' Technical 
Guidance for Assessing the Effects of Anthropogenic Sound on Marine 
Mammal Hearing (Version 2.0) (NMFS, 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). 
As noted above, the Navy's planned activity includes the use of 
impulsive and non-impulsive sources.
    These thresholds are provided in Table 4. The references, analysis, 
and methodology used in the development of the thresholds are described 
in NMFS' 2018 Technical Guidance, which may be accessed at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance.

                     Table 4--Thresholds Identifying the Onset of Permanent Threshold Shift
----------------------------------------------------------------------------------------------------------------
                                                    PTS onset acoustic thresholds \*\ (received level)
             Hearing group              ------------------------------------------------------------------------
                                                  Impulsive                         Non-impulsive
----------------------------------------------------------------------------------------------------------------
High-Frequency (HF) Cetaceans..........  Cell 5: Lpk,flat: 202 dB;   Cell 6: LE,HF,24h: 173 dB.
                                          LE,HF,24h: 155 dB.
Phocid Pinnipeds (PW) (Underwater).....  Cell 7: Lpk,flat: 218 dB;   Cell 8: LE,PW,24h: 201 dB.
                                          LE,PW,24h: 185 dB.
----------------------------------------------------------------------------------------------------------------
* Dual metric acoustic thresholds for impulsive sounds: Use whichever results in the largest isopleth for
  calculating PTS onset. If a non-impulsive sound has the potential of exceeding the peak sound pressure level
  thresholds associated with impulsive sounds, these thresholds should also be considered.
Note: Peak sound pressure (Lpk) has a reference value of 1 [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 (HF cetaceans and PW pinnipeds) and that the
  recommended accumulation period is 24 hours. The cumulative sound exposure level thresholds could be exceeded
  in a multitude of ways (i.e., varying exposure levels and durations, duty cycle). When possible, it is
  valuable for action proponents to indicate the conditions under which these acoustic thresholds will be
  exceeded.

    Explosive sources--Based on the best available science, NMFS uses 
the acoustic and pressure thresholds indicated in Table 5 to predict 
the onset of behavioral harassment, PTS, and non-auditory impacts. 
Because of the instantaneous nature of blasting, there is no 
established Level B behavioral harassment threshold associated with

[[Page 30424]]

the activity. A single detonation is not likely to disrupt behavioral 
patterns beyond a brief startle response, therefore, the 160 dB re 1 
[mu]Pa (rms) threshold for behavioral harassment from impulsive 
acoustic sources is not applicable. However, TTS, which (as mentioned 
previously) is a form of Level B harassment take, may occur. The 
behavioral threshold used in analyses for multiple explosive events is 
determined relative to (5 dB less than) the TTS onset threshold (DoN 
2017). The threshold associated with the onset of effect for non-
auditory injury to the gastrointestinal tract (237 dB re 1 [mu]Pa 
(peak)) is used to determine the distances at which there is a one 
percent likelihood of injury occurring, informing mitigation measures 
rather than take estimates (DoN 2017). Take estimates are based on the 
243 dB re 1 [mu]Pa (peak) threshold, the criterion used to predict the 
distances at which there is a 50 percent probability of 
gastrointestinal injury resulting from underwater explosions (DoN 
2017). During the public comment period, the Marine Mammal Commission 
noted that the thresholds for slight lung injury and mortality were 
incorrectly specified in the notice of the proposed IHA. However, the 
distances to isopleths associated with the onset of and 50 percent 
probability of gastrointestinal injury were correctly modeled, 
resulting in very small zone sizes, and the zone sizes for slight lung 
injury and mortality (although not presented here) are expected to be 
commensurate with those modeled for the City of Juneau's Statter Harbor 
project (84 FR 11066; March 25, 2019), given that both projects (1) 
analyze acoustic impacts of confined blasting in drill shafts in 
underwater bedrock within a harbor/basin, (2) utilize the same sound 
exposure level for blasting events, and (3) estimate transmission loss 
by combining spherical spreading with frequency-specific absorption 
loss to the environment. The size of the shutdown zone for blasting, 
relative to these small zones, is sufficiently large to discount the 
potential for this type of injury. The shutdown zone for blasting 
equates to the Level A harassment zone for harbor porpoises, which is a 
0.335 square kilometers (km\2\) arc-shaped area that encompasses the 
super flood basin and extends into the Piscataqua River (show in Figure 
6-5 of the IHA application). This shutdown zone fully encompasses the 
Level A harassment zone for phocids (0.01978 km\2\), and onset of 
(0.000254 km\2\) and 50 percent probability of (0.0008 km\2\) 
gastrointestinal injury zone, Further, the Navy will not begin blasting 
activities until one sheet pile face of the west closure wall is 
installed, thus providing an additional barrier to sound propagating 
into the environment beyond the super flood basin (reducing the maximum 
ensonified zone from 0.418 km\2\ to 0.335 km\2\). In addition, the Navy 
will install a double bubble curtain at the entrance to the super flood 
basin during blasting and drilling activities within the basin, the 
attenuation from which (although not incorporated into the acoustic 
analyses presented here) will further reduce the impact of sound 
produced during these activities. The references, analysis, and 
methodology used in the development of the thresholds are described in 
NMFS 2018 Technical Guidance, which may be accessed at: http://www.nmfs.noaa.gov/pr/acoustics/guidelines.htm.

                                         Table 5--Explosive Acoustic and Pressure Thresholds for Marine Mammals
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                Level B harassment                Level A harassment                     Non-auditory
                                  ----------------------------------------------------------------------------------------------------------------------
              Group                  Behavioral (multiple                                              Gastro-intestinal tract   Gastro-intestinal tract
                                         detonations)               TTS                  PTS              (onset of effect)             (injury)
--------------------------------------------------------------------------------------------------------------------------------------------------------
High-Frequency (HF) Cetaceans....  135 dB SEL.............  140 dB SEL or 196    155 dB SEL or 202    237 dB SPLpk............  243 dB SPLpk
                                                             dB SPLpk.            dB SPLpk.
Phocid Pinnipeds (PW)              165 dB SEL.............  170 dB SEL or 212    185 dB SEL or 218
 (Underwater).                                               dB SPLpk.            dB SPLpk.
--------------------------------------------------------------------------------------------------------------------------------------------------------

Ensonified Area

    The operational and environmental parameters of the activity that 
fed into identifying the area ensonified above the acoustic thresholds, 
which include source levels and transmission loss, are described below.
Source Levels
    The project includes impact pile driving, vibratory pile driving 
and pile removal, drilling, and blasting. Of these, only drilling and 
vibratory pile driving will occur concurrently. When two continuous 
noise sources have overlapping sound fields, there is a potential for 
higher sound levels (and a larger associated ensonified zone) than for 
non-overlapping sources. When drilling and vibratory pile driving co-
occur, the larger of the two shutdown zones will trigger mitigation 
measures.
    Source levels of pile driving activities are based on reviews of 
measurements of the same or similar types and dimensions of piles 
available in the literature. Source levels for impact pile driving of a 
30-inch steel pipe pile are used as a proxy for impact driving of 28-
inch Z-shaped steel sheet piles (NAVFAC, 2020). Similarly, source 
levels for impact pile driving of an 18-inch flat-webbed sheet pile 
were unavailable, so proxy values for installation of a 24-inch Z-
shaped sheet pile are used. In the notice of the proposed IHA, the 
proxy source levels were incorrectly specified. As a result of NMFS' 
review of public comment, the approach to estimating the source levels 
for this pile type was modified by taking the mean of the maximum 
values for each type of sound level in Table 1.6-5 of CALTRANS (2015), 
resulting in the decreased source levels shown in Table 6.
    The source levels in Table 6 are assumed for pile driving and 
drilling underwater noise produced by construction activities.

[[Page 30425]]



                             Table 6--Summary of In-Water Pile Driving Source Levels
                                              [at 10 m from source]
----------------------------------------------------------------------------------------------------------------
                                  Installation/                                   SPLrms, dB  re
           Pile type               extraction      Pile diameter   SPLpk, dB  re    1 [micro]Pa    SEL, dB  re 1
                                     method           (inch)        1 [micro]Pa                   [micro]Pa\2\-s
----------------------------------------------------------------------------------------------------------------
Z-shaped steel sheet \1\ \3\..  Vibratory \2\...              28              NA             167             167
                                Impact \3\......              28             211             196             181
Flat-webbed steel sheet \1\     Vibratory.......              18              NA             163             163
 \4\.
                                Impact..........              18             201             183             172
Steel pipe \2\................  Vibratory.......              30              NA             167             167
Blast holes \5\...............  Drilling........             4.5              NA           166.2           166.2
----------------------------------------------------------------------------------------------------------------
Key: dB = decibels; NA = Not applicable; dB re 1 [mu]Pa = dB referenced to a pressure of 1 micropascal, measures
  underwater SPL. dB re 1 [mu]Pa2-s = dB referenced to a pressure of 1 micropascal squared per second, measures
  underwater SEL.
\1\ = A proxy value for 28-inch sheet piles could not be found for impact and vibratory driving so the proxy for
  a 30-inch steel pipe pile has been used (NAVFAC SW 2020). A proxy value for 18-inch flat-webbed sheet piles
  could not be found for impact and vibratory driving so the proxy for a 24-inch Z-shaped sheet pile has been
  used (CALTRANS 2015).
Sources: DoN 2015 \2\; NAVFAC SW 2020 \3\ CALTRANS 2015 \4\; Denes et al., 2016.\5\

    The proxy source level for drilling of blast-charge holes is 
derived from Denes et al. (2016), which reports sound pressure levels 
measured during rock socket drilling at Kodiak Ferry Terminal in 
Alaska. The size of the blast-charge holes considered here (4.5-inch) 
is much smaller than the size of the drilled holes (24-inch) in Denes 
et al. (2016), making the use of 166.2 dB re 1[micro]Pa conservative.
    There are no data on sound source levels from explosives used under 
circumstances identical to the blasting activity described here (e.g., 
charge composition and weight, bathymetry, substrate composition, and 
the dimensions of holes for stemmed charge placement). Therefore, the 
Navy made approximations by reference to mathematical models that have 
been empirically validated, under roughly comparable circumstances, to 
estimate source levels both in terms of absolute peak sound pressure 
level (SPL in units of dB re 1[micro]Pa) and sound exposure level (SEL 
in units of dB re 1[micro]Pa\2\-s) (Table 7). The peak source level 
calculation of a confined blast follows Cole's (1948) equation and a 
regression curve from the Miami Harbor Deepening Project (Hempen et al. 
2007), using a distance of 2.4 m and a weight of 120 pounds (lbs) for a 
single charge. Based on this approach, the peak source level for the 
project is estimated to be 257 dB re 1 [micro]Pa for a 120 lb charge. 
Following Urick (1983), the Navy estimated the SEL for 30, 120 lb 
charges at 1 m by first calculating the instantaneous pressure 
following the onset of a shock wave, as a relationship between peak 
pressure and time. Blasting operations will involve detonating 120 lb 
up to 30 times in rapid succession, with a split second delay between 
each detonation. Without specific information regarding the layout of 
the charges, the modeling assumes a grid of 2.4 m by 2.4 m charges for 
the majority of the super flood basin, and 1.5 m by 1.8 m for the rows 
closest to Berth 11. Due to time and spatial separation of each single 
charge by a distance of 2.4 m, the accumulation of acoustic energy is 
added sequentially, assuming the transmission loss follows cylindrical 
spreading within the matrix of charges. Using this approach for 
multiple confined charges, the modeled source SEL for 30, 120 lb 
charges at 1 m is estimated to be 227 dB re 1[micro]Pa\2\-s. Please see 
the Navy's IHA application for more details regarding these 
calculations.

                     Table 7--Blasting Source Levels
------------------------------------------------------------------------
                                               SPLpk, (dB   SEL (dB re 1
              Explosive charge                    re 1     [micro]Pa\2\-
                                               [micro]Pa)        s)
------------------------------------------------------------------------
30 x 120 lb charge..........................         257           227
------------------------------------------------------------------------

    These source levels for pile driving, drilling, and blasting are 
used to estimate the Level B harassment zones and calculate the Level A 
harassment zones.
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:

(1) TL = B * log10(R1/R2)

Where,

R1 = the distance of the modeled SPL from the driven pile, and
R2 = the distance from the driven pile of the initial measurement.

    The degree to which underwater sound propagates away from a sound 
source is dependent on a variety of factors, most notably the water 
bathymetry and presence or absence of reflective or absorptive 
conditions including in-water structures and sediments. Spherical 
spreading occurs in a perfectly unobstructed (free-field) environment 
not limited by depth or water surface, resulting in a 6 dB reduction in 
sound level for each doubling of distance from the source 
(20*log[range]). Cylindrical spreading occurs in an environment in 
which sound propagation is bounded by the water surface and sea bottom, 
resulting in a reduction of 3 dB in sound level for each doubling of 
distance from the source (10*log[range]). A practical spreading value 
of 15 is often used under conditions, such as at the Shipyard dock, 
where water increases with depth as the receiver moves away from the 
shoreline, resulting in an expected propagation environment that would 
lie between spherical and cylindrical spreading loss conditions. The 
Level B harassment distances for construction activities are calculated 
using practical spreading (impact and vibratory pile driving, drilling) 
and spherical spreading with absorption (blasting), which includes an 
additional term in the equation that accounts for frequency-specific 
transmission loss to the environment due to absorption, using the 
source levels provided in Tables 6 and 7, respectively.
    Ensonified areas (A) are calculated using the following equation.

(2) A = [pi]R\2\

Where,

R is the harassment distance.

    However, the maximum distance from the source is capped due to 
landmass interception in the surrounding area. For this reason, the 
maximum area that could be ensonified by noise from pile driving and 
drilling is an estimated 0.418 km\2\. Therefore, all harassment zones 
that are larger than 0.418 km\2\ are corrected to this maximum value. 
The

[[Page 30426]]

maximum ensonified area for blasting is smaller (0.335 km\2\) because, 
prior to the removal of bedrock, a portion of the west closure wall 
will be installed, providing an additional boundary between noise 
produced within the super flood basin and the surrounding environment.
Level A Harassment Zones
    When the original NMFS Technical Guidance (2016) was published, in 
recognition of the fact that the ensonified area/volume could be more 
technically challenging to predict because of the duration component in 
the new thresholds, NMFS developed a User Spreadsheet that includes 
tools to help predict a simple isopleth that can be used in conjunction 
with marine mammal density or occurrence to help predict takes. NMFS 
notes that because of some of the assumptions included in the methods 
used for these tools, NMFS anticipates that isopleths produced are 
typically going to be overestimates of some degree, which may result in 
some degree of overestimate of Level A harassment take. However, these 
tools offer the best way to predict appropriate isopleths when more 
sophisticated 3D modeling methods are not available, and NMFS continues 
to develop ways to quantitatively refine these tools, and will 
qualitatively address the output where appropriate. For stationary 
sources such as in-water vibratory and impact pile driving, NMFS User 
Spreadsheet predicts the closest distance at which, if a marine mammal 
remained at that distance the entire duration of the activity, it would 
not incur PTS. Inputs used in the User Spreadsheet (i.e., pile driving 
duration or number of strikes per pile, and the number of piles 
installed or removed per day) used to calculate distances to the Level 
A harassment isopleths for pile driving and drilling are shown in Table 
8.
    For blasting, the calculated distances to Level A harassment 
thresholds are based on a single blast event per day. The Navy plans to 
conduct 150 blast events over 130 days, so on the majority of 
construction days (110) only one blast event will occur. NMFS 
recognizes that if two blasts do occur on a single day, the cumulative 
SEL for the 24-hour timeframe over which blasting occurs would be 
higher than that analyzed here. However, the distances to the Level A 
harassment thresholds in Table 9 do not reflect the attenuating 
influence of the double bubble curtain that will be in place across any 
openings between the super flood basin and the surrounding environment 
during blasting events. If multiple blast events occur within a 24-hour 
period, they will be separated by 4 to 5 hours. It is likely that if 
marine mammals are present in the vicinity of the construction area 
(outside of the shutdown zone) during the first blast event they will 
avoid the area for at least the remainder of day.
    Blasting will occur at multiple locations within the super flood 
basin. The minimum and maximum distances from the blasting locations to 
the center of the entrance to the super flood basin are 37.5 and 160 m, 
respectively. Acoustic modeling is based on the location closest to the 
entrance to the basin; the resulting distances to Level B harassment 
and Level A harassment isopleths are, therefore, a conservative 
estimate of the maximum extent of potential acoustic impact outside of 
the basin. The distance to the Level A harassment isopleth for blasting 
for harbor porpoises (1,007 m) is larger than that for phocids (110 m), 
but the density of harbor porpoises near the construction area is very 
low (see Marine Mammal Occurrence section). Harbor seals and gray seals 
are more common, but the distance to the Level A harassment isopleth 
for phocids is fully encompassed by the shutdown zone.
    The Level A harassment zones are calculated using the same Equation 
(2). For all pile driving/drilling activities, ensonified areas are 
based on distances to the cumulative SEL Level A harassment thresholds 
using the NMFS acoustic guidance (NMFS 2018) because they were larger 
than the values calculated against the SPLpeak criteria. 
Following the approach used for estimating Level B harassment zones, if 
the calculated value is larger than the maximum potential ensonified 
zone, Level A harassment zones are corrected to 0.418 km\2\ for pile 
driving activity and 0.335 km\2\ for blasting activity.
    The calculated distances to Level A harassment and non-auditory 
injury (to the gastrointestinal tract) isopleths, estimated distances 
to Level B harassment isopleths, and associated ensonified areas for 
the marine mammal species likely to be affected by the construction 
activities are provided in Tables 8 and 9.

                                     Table 8--Distances and Areas of Harassment Zones for Pile Driving and Drilling
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                   Level A harassment                Level B harassment
                                                                                     -------------------------------------------------------------------
                                    Pile size, type,   Number of strikes/  Number of        HF cetacean              Phocid
            Activity                    and rate        pile or duration      days   ----------------------------------------------               Area
                                                                                                     Area                   Area    Dist. (m)   (km\2\)
                                                                                      Dist. (m)    (km\2\)    Dist. (m)   (km\2\)
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                        Impulsive
--------------------------------------------------------------------------------------------------------------------------------------------------------
Construct west closure wall.....  18-inch flat-webbed  300...............         13        516        0.258        232      0.068        341      0.126
                                   sheet pile (12
                                   pile/day).
Entrance structure closure walls  28-inch Z-shaped     300...............          4      2,056        0.418        923      0.395      2,512      0.418
                                   sheet pile (12
                                   pile/day).
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                      Non-impulsive
--------------------------------------------------------------------------------------------------------------------------------------------------------
Construct west closure wall.....  18-inch flat-webbed  5 min/pile 60 min/         13       13.7     0.000556        5.6    0.00098      7,356      0.418
                                   sheet pile (12       day.
                                   pile/day).
Install west closure wall         30-inch steel pipe   5 min/pile 15 min/          5       10.1     0.000319        4.1   0.000053     13,594      0.418
 template.                         pile (3 pile/day).   day.
Remove west closure wall          30-inch steel pipe   5 min/pile 15 min/          5       10.1     0.000319        4.1   0.000053     13,594      0.418
 template.                         pile (3 pile/day).   day.
Remove temporary dolphins.......  30-inch steel pipe   5 min/pile 40 min/          2       19.4      0.01068        8.0   0.001996     13,594      0.418
                                   pile (8 pile/day).   day.
Entrance structure closure walls  28-inch Z-shaped     5 min/pile 60 min/          4       25.4   0.00174675       10.4   0.000338     13,594      0.418
                                   sheet pile (12       day.
                                   pile/day).

[[Page 30427]]

 
Bedrock drilling for blast        4.5-inch (1,580      12 hr/day.........        130          7     0.000153        4.3   0.000058     12,023      0.418
 charges.                          holes).
--------------------------------------------------------------------------------------------------------------------------------------------------------
* 0.418 km\2\ is the maximum ensonified area in the project area for pile driving and drilling due to landmass interception of sound propagation.


                                              Table 9--Distances and Areas of Harassment Zones for Blasting
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                 Level A (PTS onset) harassment \1\   Level B (behavioral) harassment          Non-auditory injury
                                                -----------------------------------------------------------------------     (gastrointestinal tract)
                                                                                                                       ---------------------------------
                                                                                                                         Phocid/harbor
                                                  Harbor porpoise  Phocids distance   Harbor porpoise      Phocids          porpoise      Phocid/harbor
  Blasting events and charge     Blasting days    distance to 155  to 185 dB SELcum   distance to 135  distance to 165  distance to 237      porpoise
                                                     dB SELcum      threshold/area       dB SELcum        dB SELcum         dB peak      distance to 243
                                                  threshold/area        of ZOI        threshold/area    threshold/area      pressure         dB peak
                                                      of ZOI                              of ZOI            of ZOI       threshold/area      pressure
                                                                                                                         of ZOI (onset    threshold/area
                                                                                                                           of effect)    of ZOI (injury)
--------------------------------------------------------------------------------------------------------------------------------------------------------
5-30 blasts per event, 120-lb  130 (1-2 events/  1,007 m/0.335     110 m/0.01978     2,131 m/0.335     577 m/0.27636    9 m/0.000254     5 m/0.00008
 charge per blast event, 150    day).             km\2\.            km\2\.            km\2\.            km\2\.           km\2\.           km\2\
 blast events.
--------------------------------------------------------------------------------------------------------------------------------------------------------
* 0.335 km\2\ is the maximum ensonified area for blasting in the project area due to landmass interception of sound propagation.
\1\ Distance to 202 dB SPLpeak threshold for harbor porpoises is 19 m, and to 218 dB SPLpeak threshold for phocids is 3 m.

Marine Mammal Occurrence

    Marine mammal density estimates for the harbor porpoise, harbor 
seal, and gray seal are based on marine mammal monitoring observations 
during 2017 and 2018 (CIANBRO 2018a, b). Density values were calculated 
from visual sightings of all marine mammals divided by the monitoring 
days (total of 154 days) and the total ensonified area in which the 
sightings occurred in the 2017 and 2018 activities (0.8401 km\2\). 
Details used for calculations are provided in Table 10 and described 
below.

      Table 10--Marine Mammal Sightings and Resulting Density in the Vicinity of Portsmouth Naval Shipyard
----------------------------------------------------------------------------------------------------------------
                                                 2017 sighting   2018 sighting                  Density  (animal/
                    Species                        (96 days)       (58 days)    Total sighting      day/km\2\)
----------------------------------------------------------------------------------------------------------------
Harbor porpoise...............................               3               2               5              0.04
Harbor seal...................................             199             122             321              2.48
Gray seal.....................................              24               2              26              0.20
----------------------------------------------------------------------------------------------------------------

    Hooded and harp seals are much rarer than harbor and gray seals in 
the Piscataqua River, and no density information for these two species 
is available. To date, marine mammal monitoring for the Berth 11 
Waterfront Improvements Construction project has not recorded a 
sighting of a hooded or harp seal in the project area (Cianbro 2018ab; 
NAVFAC Mid-Atlantic 2018, 2019b; Navy 2019; Stantec 2020); however, two 
harp seals were observed outside of the timeframe of dedicated marine 
mammal monitoring of Berth 11 pile-driving activities, one on May 12, 
2020 and one on May 14, 2020 (Stantec 2020). The Navy requested 
authorization of take for these two species, given the potential for 
occurrence, and NMFS is acting on that request.

Take Calculation and Estimation

    The approach by which the information provided above is brought 
together to produce a quantitative take estimate is described here.
    For marine mammals with calculated density information (i.e., 
harbor porpoise, harbor seal, and gray seal), in general, estimated 
Level B harassment and Level A harassment take numbers are calculated 
using the following equation:

Estimated take = animal density x ensonified area x operating days (3)

    However, in consideration of the prevalence of seals in the project 
area and in accordance with the approach utilized in IHAs previously 
issued to the Navy for expansion and modification of DD1, NMFS has 
determined that it is appropriate to increase the number of harbor seal 
and gray seal Level B behavioral harassment takes. Harbor seal Level B 
behavioral harassment takes have been adjusted upwards by multiplying 
the average number of harbor seals sighted per day from May through 
December 2020 (721 sightings divided by 150 days of monitoring, or 5 
harbor seals/day) by the number of actual construction days (159), 
resulting in 795 Level B behavioral harassment takes. Gray seal Level B 
harassment takes have been increased utilizing the same approach (47 
sightings divided by 150 days of monitoring, or 0.31 gray seals/day), 
resulting in 50 Level B behavioral harassment takes.
    NMFS authorized one Level B harassment take per month for both 
hooded seals and harp seals for the Berth 11 Waterfront Improvements 
construction project in both 2018 and 2019. Following the same 
approach, the Navy has requested, and NMFS has authorized, one Level B 
harassment take each of hooded seals and harp seals per

[[Page 30428]]

month of construction from January through May, when these species may 
occur in the vicinity of DD1 (total of 5 Level B harassment takes for 
each species).
    The total number of takes authorized is presented in Table 11. Non-
auditory take estimates were zero for all species and are, therefore, 
not included in Table 11.
BILLING CODE 3510-22-P

[[Page 30429]]

[GRAPHIC] [TIFF OMITTED] TN08JN21.017


[[Page 30430]]


BILLING CODE 3510-22-C

Mitigation Requirements

    In order to issue an IHA under Section 101(a)(5)(D) of the MMPA, 
NMFS must set forth the permissible methods of taking pursuant to such 
activity, and other means of effecting the least practicable impact on 
such species or stock and its habitat, paying particular attention to 
rookeries, mating grounds, and areas of similar significance, and on 
the availability of such species or stock for taking for certain 
subsistence uses. NMFS regulations require applicants for incidental 
take authorizations to include information about the availability and 
feasibility (economic and technological) of equipment, methods, and 
manner of conducting such activity or other means of effecting the 
least practicable adverse impact upon the affected species or stocks 
and their habitat (50 CFR 216.104(a)(11)).
    In evaluating how mitigation may or may not be appropriate to 
ensure the least practicable adverse impact on species or stocks and 
their habitat, as well as subsistence uses where applicable, NMFS 
carefully considers two primary factors:
    (1) The manner in which, and the degree to which, the successful 
implementation of the measure(s) is expected to reduce impacts to 
marine mammals, marine mammal species or stocks, and their habitat. 
This considers the nature of the potential adverse impact being 
mitigated (likelihood, scope, range). It further considers the 
likelihood that the measure will be effective if implemented 
(probability of accomplishing the mitigating result if implemented as 
planned), the likelihood of effective implementation (probability 
implemented as planned); and
    (2) The practicability of the measures for applicant 
implementation, which may consider such things as cost, impact on 
operations, and, in the case of a military readiness activity, 
personnel safety, practicality of implementation, and impact on the 
effectiveness of the military readiness activity.
    In addition to the measures described later in this section, the 
Navy will employ the following standard mitigation measures:
     The Navy must employ PSOs, establish monitoring locations, 
and monitor the project area to the maximum extent possible based on 
the required number of PSOs, required monitoring locations, and 
environmental conditions;
     Monitoring must take place from 30 minutes prior to 
initiation of construction activities through 30 minutes post-
completion of pile-driving and drilling, and 60 minutes post-completion 
of blasting events;
     The Navy must conduct a briefing between construction 
supervisors and crews and the marine mammal monitoring team prior to 
the start of construction, and when new personnel join the work, to 
explain responsibilities, communication procedures, marine mammal 
monitoring protocol, and operational procedures;
     For in-water and over-water heavy machinery work, if a 
marine mammal comes within 10 m, operations shall cease and vessels 
shall reduce speed to the minimum level required to maintain steerage 
and safe working conditions;
     With the exception of pre-dawn drilling, work must only 
occur during daylight hours, when visual monitoring of marine mammals 
can be conducted;
     For those marine mammals for which take has not been 
requested, pile driving and removal, drilling, and blasting will shut 
down immediately when the animals are sighted approaching the Level B 
harassment zone;
     If take reaches the authorized limit for an authorized 
species, activity for which take is authorized will be stopped as these 
species approach the Level B harassment zone to avoid additional take;
     Blasting will not begin until at least one sheet pile face 
of the west closure wall has been installed;
     Blasting must only occur in good visibility conditions 
between 30 minutes after sunrise and one hour before sunset;
     Stemming procedures must be used for blasting events; and
     A double bubble curtain will be installed across any 
openings at the entrance of DD1 to mitigate underwater noise impacts 
outside of the super flood basin during pre-dawn drilling of blast-
charge holes and blasting events.
    The following measures will apply to the Navy's mitigation 
requirements:
    Monitoring Harassment Zones--Before the commencement of in-water 
construction activities (i.e., impact pile driving, vibratory pile 
driving and pile removal, drilling, and blasting), Level B harassment 
and Level A harassment zones must be established for purposes of 
monitoring. Monitoring zones enable observers to be aware of and 
communicate the presence of marine mammals in the project area outside 
of the shutdown zone (see below) and thus prepare for a potential cease 
of activity should the animal enter the shutdown zone. All Level B 
harassment monitoring zones for the construction activities are 
equivalent to the maximum ensonified zone, adjusted for landmass 
interception, or 0.418 km\2\. Similarly, harassment monitoring zones 
must be established for the PTS isopleths associated with each 
functional hearing group.
    Shutdown Zones--The Navy will implement shutdown zones for all pile 
driving and removal, drilling, and blasting activities. The purpose of 
a shutdown is to prevent some undesirable outcome, such as auditory 
injury or severe behavioral disturbance of sensitive species, by 
halting the activity. If a marine mammal is observed entering or within 
the respective shutdown zone (Table 12) after a construction activity 
has begun, the PSO will request a temporary cessation of the 
construction activity. On days when multiple activities are occurring 
concurrently, the largest shutdown zone between/among the activities 
will be implemented. The shutdown zone for blasting will be the entire 
region of influence (ROI), equivalent to the maximum ensonified zone 
adjusted for landmass interception (0.335 km\2\). If shutdown zones are 
obscured by fog or poor lighting conditions, pile-driving and blasting 
will not be initiated until the entire shutdown zones are visible.
    Although drilling activities may occur during pre-dawn hours in 
order to maintain the project schedule, the shutdown distance for 
drilling is small (10 m) and will likely be entirely visible for 
monitoring despite visibility limitations during this timeframe. As 
mentioned previously, drilling will not occur between sunset and pre-
dawn hours.
    Shutdown zones typically vary based on the activity type and marine 
mammal hearing group. A summary of the shutdown zones is provided in 
Table 12.

[[Page 30431]]



   Table 12--Shutdown Zones Distances for Construction Activities and
                      Marine Mammal Hearing Groups
------------------------------------------------------------------------
                                          Shutdown distance (m)
   Pile type, size & driving    ----------------------------------------
             method                  HF cetacean            Phocid
------------------------------------------------------------------------
Vibratory drive 30-inch steel    70.................  30
 pipe piles.
Vibratory extraction 30-inch     70.................  30.
 steel pipe piles.
Impact drive 28-inch steel       110................  50.
 sheet piles.
Vibratory drive 28-inch steel    25.................  10.
 sheet piles.
Impact drive 18-inch sheet       110................  50.
 piles.
Vibratory drive 18-inch sheet    15.................  10.
 piles.
Drilling 4.5-inch blast charge   10.................  10.
 holes.
Blasting 120 lb charge.........  Entire ROI \1\.....  Entire ROI.
------------------------------------------------------------------------
\1\ Region of influence (ROI) for blasting is the maximum ensonified
  area (0.335 km\2\).

    Pre-start Clearance Monitoring--Prior to the start of daily in-
water construction activity, or whenever a break in pile driving/
removal or drilling of 30 minutes or longer occurs, PSOs will observe 
the shutdown zones for a period of 30 minutes. The shutdown zone will 
be considered cleared when a marine mammal has not been observed within 
the zone for that 30-minute period. If a marine mammal is observed 
within the shutdown zone, no construction activity, including soft-
start (see below), can proceed until the animal has voluntarily left 
the zone or has not been observed for 15 minutes. When a marine mammal 
for which Level B harassment take is authorized is present in the Level 
B harassment zone, activities may begin. If the entire Level B 
harassment zone is not visible at the start of construction, pile 
driving activities can begin. If work ceases for more than 30 minutes, 
the pre-activity monitoring of the shutdown zones will commence.
    Soft Start--The use of a soft start procedure is believed to 
provide additional protection to marine mammals by warning marine 
mammals or providing them with a chance to leave the area prior to the 
hammer operating at full capacity, and typically involves a requirement 
to initiate sound from the hammer at reduced energy followed by a 
waiting period. The Navy will provide an initial set of strikes from 
the impact hammer at reduced energy, followed by a 30 second waiting 
period, and then two subsequent sets. NMFS notes that it is difficult 
to specify the reduction in energy for any given hammer because of 
variation across drivers and, for impact hammers, the actual number of 
strikes at reduced energy will vary because operating the hammer at 
less than full power results in ``bouncing'' of the hammer as it 
strikes the pile, resulting in multiple ``strikes''. Soft start will be 
implemented at the start of each day's impact pile driving and at any 
time following cessation of impact pile driving for a period of 30 
minutes or longer.
    Based on our evaluation of the required measures, NMFS has 
determined that the prescribed mitigation measures provide the means 
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.

Monitoring and Reporting Requirements

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

Monitoring Requirements

    The Navy shall employ trained PSOs to conduct marine mammal 
monitoring for its PNSY modification and expansion project. The 
purposes of marine mammal monitoring are to implement mitigation 
measures and learn more about impacts to marine mammals from the Navy's 
construction activities.
Protected Species Observer Qualifications
    NMFS-approved PSOs shall meet the following requirements:
    1. Independent observers (i.e., not construction personnel) are 
required;
    2. At least one observer must have prior experience working as an 
observer;
    3. Other observers may substitute education (undergraduate degree 
in biological science or related field) or training for experience;
    4. Where a team of three or more observers are required, one 
observer should be designated as lead observer or monitoring 
coordinator. The lead observer must have prior experience working as an 
observer; and
    5. NMFS will require submission and approval of observer curricula 
vitae (CVs).

[[Page 30432]]

Marine Mammal Monitoring Protocols
    The Navy will monitor all Level B harassment zones and Level A 
harassment zones before, during, and after construction activities. The 
Marine Mammal Monitoring Plan must include the following procedures:
     At least two (2) PSOs shall be posted to monitor marine 
mammals during in-water pile driving and removal, drilling, and 
blasting. Additional PSOs will be required in conditions of low 
visibility (i.e., rain or light fog), for activities producing the 
largest ensonified zones, and/or if marine mammal occurrence is higher 
than expected in the project area;
     PSOs must be stationed at the best possible vantage 
point(s) in order to properly see the entire shutdown zone(s) and zones 
associated with behavioral impact thresholds, which may include the 
following locations: Berth 2, Berth 12, Isle of Shoals Steamship 
Company, Prescott Park, Four Tree Island, Peirce Island, and/or a boat 
or barge within the project limits;
     PSOs must record all observations of marine mammals, 
regardless of distance from the construction activity;
     During all observation periods, PSOs will use high-
magnification (25X), as well as standard handheld (7X) binoculars, and 
the naked eye to search continuously for marine mammals;
     Monitoring distances will be measured with range finders. 
Distances to animals will be based on the best estimate of the PSO, 
relative to known distances to objects in the vicinity of the PSO;
     Pile driving and removal, drilling, and blasting will only 
take place when the shutdown zones are visible and can be adequately 
monitored. If conditions (e.g., fog) prevent the visual detection of 
marine mammals, activities with the potential to result in Level A 
harassment shall not be initiated. If such conditions arise after the 
activity has begun, blasting and impact pile driving or removal will be 
halted but drilling and vibratory pile driving or removal will be 
allowed to continue;
    Information Collection:
    PSOs shall collect the following information during marine mammal 
monitoring:
    [cir] PSO locations during monitoring;
    [cir] Date and time that monitored activity begins and ends for 
each day conducted (monitoring period);
    [cir] Construction activities occurring during each daily 
observation period, including how many and what type of piles driven, 
number of blast holes drilled, and number or blast events;
    [cir] Environmental conditions during monitoring periods (at 
beginning and end of PSO shift and whenever conditions change 
significantly); including Beaufort sea state and any other relevant 
weather conditions, including cloud cover, fog, sun glare, and 
estimated observable distance;
    [cir] For each marine mammal sighting:
     Name of PSO who sighted the animal(s) and PSO location and 
activity at time of sighting;
     Time of sighting;
     Species, numbers, and, if possible, sex and age class of 
marine mammals;
     Description of any observable marine mammal behavior 
patterns, including bearing and direction of travel and distance from 
construction activity;
     Location, distance, and bearing from pile driving, 
drilling, and blasting activities to marine mammals and distance from 
the marine mammals to the observation point;
     Animal's closet point of approach and estimated amount of 
time that the animals remained in the Level B harassment and Level A 
harassment zones; and
     Detailed information about implementation of any 
mitigation (e.g., shutdowns or delays), a description of specific 
actions that ensued, and resulting changes in behavior of the 
animal(s), if any.
     Percentage of time that activities (i.e., drilling) occur 
at night.
Hydroacoustic Monitoring
    The Navy must conduct hydroacoustic monitoring of in-water 
construction activities, including the installation of (10) 28-inch Z-
shaped sheet piles and (10) 18-inch flat-webbed sheet piles for both 
impact and vibratory pile driving, (4) 30-inch steel piles for 
vibratory pile driving, (10) 120 lbs blasting events, and (10) 4.5-inch 
blast-charge hole drilling events. Near-field monitoring will occur at 
10 m from the pile driving hammers and drilling location. During 
blasting, near-field data will be collected using a pressure transducer 
to estimate sounds levels based on received impulse. The far-field 
hydrophone will be placed as far from the acoustic source as is 
practicable, although the distance will limited by DD1's proximity to a 
navigable channel outside of the entrance to the super flood basin. 
Monitoring will only be conducted when concurrent activities are not 
occurring, limiting interference in the recordings from other sources 
of noise in the environment.

Reporting Requirements

    The Navy is required to submit a draft monitoring report (including 
all PSO data sheets and/or raw sighting data) within 90 days after 
completion of the construction work or the expiration of the IHA, 
whichever comes earlier. This report must detail the monitoring 
protocol, summarize the data recorded during monitoring, and estimate 
the number of marine mammals that may have been harassed. The draft 
hydroacoustic monitoring report must be submitted within the same 
timeframe and must contain the informational elements described in the 
hydroacoustic monitoring plan for all acoustically monitored events, 
including: A description of the hydrophones used, hydrophone locations 
(both near- and far-field) and water depths, recording device(s), 
distance from the acoustic source, and sediment type at the recording 
location; type and size of pile being driven, method of pile-driving 
during recording (hammer model and energy), and total driving/removal 
or drilling duration. For impact pile driving, the Navy must also 
report: Number of strikes and strike rate, depth of substrate 
penetrated, pulse duration, and mean, median, and maximum sound levels 
(db re 1 [micro] Pa) (root mean square sound pressure level 
(SPLrms); cumulative sound exposure level 
(SELcum), peak sound pressure level (SPLpeak), 
and single-strike sound exposure level (SELs-s)). For 
vibratory pile driving or removal and drilling, the Navy must also 
report: Median, minimum and maximum sound levels (db re 1 [micro] Pa) 
(SPLrms, SELcum), and the timeframe over which the sound is averaged. 
For blast events, the Navy must also report: Number of blast events per 
day, time between blast events if two are conducted within a 24-hour 
period, total number of charges/delays, maximum net explosive weight 
(NEW) of a single charge and the total NEW of the event, timeframe 
between delays and total timeframe of event, impulse in Pa-sec, 
SPLpeak for each event and SELcum values for the 
entire 24 hours over which blasting occurs. For all activities, 
reported SPLrms values must be based on a time window that 
consists of 90 percent of the acoustic energy. Power spectral density 
plots and one-third octave band spectra must be provided for all 
acoustically monitored construction activities. If, for any reason, the 
total number of events included in the hydroacoustic monitoring plan 
are not monitored within the overall construction timeframe, the Navy 
must report the actual number of events monitored. NMFS will have an 
opportunity to provide comments on the report and, if NMFS has 
comments, the Navy will address the comments and submit a final report 
to NMFS within 30 days.

[[Page 30433]]

    The Navy is required to notify NMFS' Office of Protected Resources 
(OPR) and NMFS' Greater Atlantic Regional Stranding Coordinator or 
local stranding network at least 24 hours prior to commencing blasting 
events as well as within 24 hours after blasting events cease. If 
blasting events occur on consecutive days, the Navy must communicate 
how long the blasting is scheduled to last as well as when it is 
completed. In addition, in the event that personnel involved in the 
construction activities discover an injured or dead marine mammal, the 
Navy must immediately report the incident to NMFS OPR and the Stranding 
Coordinator or local stranding network and follow any instructions 
provided by the Stranding Coordinator or stranding network. If the 
death or injury was clearly caused by the specific activity, the Navy 
must immediately cease the specified activities until NMFS OPR is able 
to review the circumstances of the incident and determine what, if any, 
additional measures are appropriate to ensure compliance with the terms 
of the IHA. The Navy must not resume their activities until notified by 
NMFS OPR. The Navy shall provide NMFS OPR and the Stranding Coordinator 
or local stranding network with the species or description of the 
animal(s), the condition of the animal(s) (including carcass condition, 
if the animal is dead), location, time of first discovery, observed 
behaviors (if alive), and photo or video (if available).
    In the event that the Navy finds an injured or dead marine mammal 
that is not in the construction area, the Navy would report the same 
information as listed above to the Stranding Coordinator or local 
stranding network and NMFS OPR as soon as is operationally feasible.

Negligible Impact Analysis and Determination

    NMFS has defined negligible impact as an impact resulting from the 
specified activity that cannot be reasonably expected to, and is not 
reasonably likely to, adversely affect the species or stock through 
effects on annual rates of recruitment or survival (50 CFR 216.103). A 
negligible impact finding is based on the lack of likely adverse 
effects on annual rates of recruitment or survival (i.e., population-
level effects). An estimate of the number of takes alone is not enough 
information on which to base an impact determination. In addition to 
considering estimates of the number of marine mammals that might be 
``taken'' through harassment, NMFS considers other factors, such as the 
likely nature of any responses (e.g., intensity, duration), the context 
of any responses (e.g., critical reproductive time or location, 
migration), as well as effects on habitat, and the likely effectiveness 
of the mitigation. NMFS also assesses the number, intensity, and 
context of estimated takes by evaluating this information relative to 
population status. Consistent with the 1989 preamble for NMFS' 
implementing regulations (54 FR 40338; September 29, 1989), the impacts 
from other past and ongoing anthropogenic activities are incorporated 
into this analysis via their impacts on the environmental baseline 
(e.g., as reflected in the regulatory status of the species, population 
size and growth rate where known, ongoing sources of human-caused 
mortality, or ambient noise levels).
    Pile driving and removal, drilling, and blasting activities 
associated with the project, as described previously, have the 
potential to disturb or temporarily displace marine mammals. The 
specified activities may result in take, in the form of Level A 
harassment (potential injury; from impact pile driving or blasting) or 
Level B harassment (potential behavioral disturbance or TTS) from 
underwater sounds generated from pile driving (impact and vibratory), 
drilling and blasting. Potential takes could occur if individual marine 
mammals are present in the ensonified zone when pile driving, drilling, 
or blasting activities are occurring.
    To avoid repetition, this introductory discussion of NMFS' analysis 
applies to all of the species listed in Table 2, given that the 
anticipated effects of the Navy's PNSY modification and expansion 
construction project activities on marine mammals are expected to be 
relatively similar in nature. There is no information about the nature 
or severity of the impacts, or the size, status, or structure of any 
species or stock that would lead to a different analysis by species for 
this activity, or else species-specific factors would be identified and 
analyzed.
    Although some individual harbor porpoises and harbor and gray seals 
are estimated to experience Level A harassment in the form of PTS if 
they remain within the impact pile driving Level A harassment zone for 
an entire day, or are present within the Level A harassment zone during 
a blasting event, the degree of injury is expected to be mild and is 
not likely to affect the reproduction or survival of the individual 
animals. It is expected that, if hearing impairments occurs as a result 
of impact pile driving or blasting, the affected animal would lose a 
few dB in its hearing sensitivity, which in most cases is not likely to 
affect its survival and recruitment. Hearing impairment that might 
occur for these individual animals would be limited to the dominant 
frequency of the noise sources, (i.e., in the low-frequency region 
below 2 kHz). Nevertheless, as for all marine mammal species, it is 
anticipated that, in general, these pinnipeds will avoid areas where 
sound levels could cause hearing impairment. Therefore, it is not 
likely that an animal would stay in an area with intense noise that 
could cause severe levels of hearing damage.
    Under the majority of the circumstances, anticipated takes are 
expected to be limited to short-term Level B behavioral harassment or 
TTS. Marine mammals present in the vicinity of the action area and 
taken by Level B harassment would most likely show overt brief 
disturbance (startle reaction) from blasting events and avoidance of 
the area impacted by elevated noise levels during pile driving (and 
removal) and drilling. Given the limited estimated number of predicted 
incidents of Level B harassment and Level A harassment and the limited, 
short-term nature of the responses by the individuals, the impacts of 
the estimated take cannot be reasonably expected to, and are not 
reasonably likely to, rise to the level that they would adversely 
affect the species considered here at the population level, through 
effects on annual rates of recruitment or survival. There are no known 
important habitats, such as rookeries or haulouts, in the vicinity of 
the Navy's PNSY DD1 modification and expansion construction project. 
The project also is not expected to have significant adverse effects on 
affected marine mammals' habitat, including prey, as analyzed in detail 
in the Potential Effects of Specified Activities on Marine Mammals and 
their Habitat section in the Federal Register notice for the proposed 
IHA (86 FR 18244; April 8, 2021).
    In summary and as described above, the following factors primarily 
support our determination that the impacts resulting from this activity 
are not expected to adversely affect the species or stock through 
effects on annual rates of recruitment or survival:
     No mortality is anticipated or authorized;
     Some individual marine mammals might experience a mild 
level of PTS, but the degree of PTS is not expected to affect their 
survival;
     Most adverse effects to marine mammals are likely to be 
temporary behavioral harassment or TTS; and

[[Page 30434]]

     No biologically important area is present in or near the 
construction area.
    Based on the analysis contained herein of the likely effects of the 
specified activity on marine mammals and their habitat, and taking into 
consideration the implementation of the monitoring and mitigation 
measures, NMFS finds that the total marine mammal take from the 
activity will have a negligible impact on all affected marine mammal 
species or stocks.

Small Numbers

    As noted above, only small numbers of incidental take may be 
authorized under section 101(a)(5)(A) and (D) of the MMPA for specified 
activities other than military readiness activities. The MMPA does not 
define small numbers and so, in practice, NMFS compares the number of 
individuals taken to the most appropriate estimation of abundance of 
the relevant species or stock in our determination of whether an 
authorization is limited to small numbers of marine mammals. When the 
predicted number of individuals to be taken is less than one third of 
the species or stock abundance, the take is considered to be of small 
numbers. Additionally, other qualitative factors may be considered in 
the analysis, such as the temporal or spatial scale of the activities.
    NMFS authorizes incidental take of 5 marine mammal stocks. The 
total amount of take authorized is three percent or less for all five 
of these stocks (Table 11).
    Based on the analysis contained herein of the activity (including 
the prescribed mitigation and monitoring measures) and the anticipated 
take of marine mammals, NMFS finds that small numbers of marine mammals 
will be taken relative to the population size of the affected species 
or stocks.

Unmitigable Adverse Impact Analysis and Determination

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

Endangered Species Act (ESA)

    No incidental take of ESA-listed species is authorized or expected 
to result from this activity. Therefore, NMFS has determined that 
formal consultation under section 7 of the ESA is not required for this 
action.

National Environmental Policy Act

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

Authorization

    As a result of these determinations, NMFS has issued an IHA to the 
Navy for the taking of marine mammals incidental to modification and 
expansion of the Portsmouth Naval Shipyard Dry Dock 1 in Kittery, 
Maine, effective for one year from the date of issuance, provided the 
previously mentioned mitigation, monitoring, and reporting requirements 
are incorporated. A copy of the final IHA can be found at https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act.

    Dated: June 3, 2021.
Catherine Marzin,
Acting Director, Office of Protected Resources, National Marine 
Fisheries Service.
[FR Doc. 2021-11983 Filed 6-7-21; 8:45 am]
BILLING CODE 3510-22-P