[Federal Register Volume 85, Number 4 (Tuesday, January 7, 2020)]
[Notices]
[Pages 673-702]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2020-00038]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

RIN 0648-XG907


Takes of Marine Mammals Incidental to Specified Activities; 
Taking Marine Mammals Incidental to Ferry Berth Improvements in Tongass 
Narrows, Alaska

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

ACTION: Notice; issuance of two incidental harassment authorizations.

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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 two consecutive incidental harassment 
authorizations (IHA) to the Alaska Department of Transportation and 
Public Facilities (ADOT&PF) to incidentally harass, by Level A and 
Level B harassment, marine mammals during two years of activity related 
to ferry berth improvements and construction in Tongass Narrows, near 
Ketchikan, AK.

DATES: The Phase 1 Authorization is effective from March 1, 2020 to 
February 28, 2021. The Phase 2 Authorization is effective from March 1, 
2021 to February 28, 2022.

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

SUPPLEMENTARY INFORMATION:

Background

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

[[Page 674]]

(referred to as ``mitigation''); and requirements pertaining to the 
mitigation, monitoring, and reporting of such takings are set forth.

Summary of Request

    On September 11, 2018, NMFS received a request from ADOT&PF for two 
consecutive IHAs to take marine mammals incidental to ferry berth 
improvements and construction in Tongass Narrows, near Ketchikan, 
Alaska. The application was deemed adequate and complete on June 11, 
2019. ADOT&PF's request was for take of a small number of eight species 
of marine mammals, by Level B harassment. Of those eight species, three 
(harbor seal (Phoca vitulina richardii), harbor porpoise (Phocoena 
phocoena), and Dall's porpoise (Phocoenoides dalli)) may also be taken 
by Level A harassment. Neither ADOT&PF nor NMFS expects serious injury 
or mortality to result from this activity and, therefore, IHAs are 
appropriate. The issued IHAs would each cover one year of the two-year 
project.

Description of Specified Activity

Overview

    ADOT&PF is planning to make improvements to existing ferry berths 
and construct new ferry berths on Gravina Island and Revilla Island in 
Tongass Narrows, near Ketchikan in southeast Alaska. These ferry 
facilities provide the only public access between the city of 
Ketchikan, AK on Revillagigedo (Revilla) Island, and the Ketchikan 
International Airport on Gravina Island (see Figure 1-2 in 
application). The project's activities that have the potential to take 
marine mammals, by Level A harassment and Level B harassment, include 
vibratory and impact pile driving, drilling operations for pile 
installation (rock socketing), and vibratory pile removal.
    Planned construction includes the installation of new ferry 
facilities and the renovation of existing structures. The marine 
construction associated with the planned activities will occur during 
two distinct year-long phases, and take associated with these phases 
would be authorized in separate, consecutive IHAs. Phase 1, which 
primarily includes both improvement of existing facilities and 
construction of new facilities on both islands, is planned to occur 
between March 1, 2020 to February 28, 2021, and Phase 2, which includes 
the improvement/refurbishing of existing facilities on both islands, is 
planned to occur from March 1, 2021, to February 28, 2022.
    In September 2019, as the ADOT&PF progressed its plans for the 2020 
construction season in Tongass Narrows, it became clear that 
considerations associated with the contracting strategy for the project 
would likely result in two or three construction sites that could be 
active concurrently during Phase 1. It is not anticipated that more 
than one construction site will be active at any time during Phase 2. 
When the proposed IHAs (84 FR 34134; July 17, 2019) was published, 
concurrent pile driving and removal activities were not expected to 
occur. However, on October 23, 2019, ADOT&PF submitted a memorandum to 
NMFS that outlined the changes to the project including concurrent pile 
driving and removal activities which resulted in revised monitoring 
zones and take estimates. All other information had been previously 
analyzed in the FR Notice for the two Proposed IHAs and remains 
unchanged. The underwater activities that may affect marine mammals, 
including species listed under the Endangered Species Act (ESA), still 
include only vibratory and impact pile installation, vibratory pile 
removal, and drilling of rock sockets. Pile numbers and sizes also 
remain consistent with the information in the proposed IHAs (84 FR 
34134; July 17, 2019).
    Section 101(a)(5)(D) specifies that ``the Secretary shall authorize 
[incidental take by harassment] for periods of not more than 1 year.'' 
In this case, the ADOT&PF knew that it would take two years to complete 
the entire project, and knew which activities would be conducted in 
each of the two years. NMFS had sufficient information to determine 
which species would be affected, the estimated amount and type of take 
that would result from the activities, and the estimated impacts to 
subsistence use from ADOT&PF's activities over each of the two years of 
the project. Thus NMFS determined that the proposed activities met all 
statutory requirements and developed appropriate mitigation, 
monitoring, and reporting requirements for both years. It is therefore 
appropriate for NMFS to issue IHAs for each of the two consecutive 
years of the project.

Dates and Duration

    In-water construction of Phase 1 is scheduled to begin on March 1, 
2020 and continue through February 28, 2021. In-water construction of 
Phase 2 is scheduled to begin on March 1, 2021 and continue through 
February 28, 2022. However, in-water pile installation/removal 
(including drilling) may occur simultaneously at one or more component 
sites during Phase 1 only. Pile installation will occur intermittently 
over the work period, for durations of minutes to hours at a time 
depending on weather, construction and mechanical delays, marine mammal 
shutdowns, and other potential delays and logistical constraints. There 
are approximately 101 days of in-water construction planned for Phase 1 
assuming that two pieces of equipment are used concurrently on 30 
percent of planned driving days. Use of three hammers on some days will 
further reduce the total number of days of pile installation. ADOT&PF 
anticipates that Phase 2 will require 27 days of in-water construction 
and will not include any concurrent pile installation or removal 
activities.

Specific Geographic Region

    The Tongass Narrows project is located within the City of 
Ketchikan, Alaska. Improvements and new construction on Revilla Island 
will occur approximately 2.6 miles north of downtown Ketchikan. A 
detailed description of the area is provided in the proposed IHAs (84 
FR 34134; July 17, 2019) and is not repeated here. Please see that 
document for more information.

Detailed Description of Specific Activity

    As discussed earlier, this project is composed of two consecutive 
phases with take of marine mammals from each phase authorized through 
separate IHAs. When necessary, the description of activity is broken 
down by phase below, but information relevant to both phases is 
presented together. Planned activities with potential to take marine 
mammals include the noise generated by drilling of rock sockets into 
bedrock for steel pipe piles, vibratory removal of steel pipe piles, 
vibratory installation of sheet piles, and vibratory and impact 
installation of steel pipe piles. Each phase of the project will 
include different activities that are described in detail in the 
following sections.
    ADOT&PF has revised its contracting approach and will use multiple 
contractors at different locations during Phase 1. While this change 
may result in up to three construction sites being active during the 
same timeframe during Phase 1, it will not change the construction 
phasing or the amount or extent of activity completed in either Phase 1 
or Phase 2. The potential exists during Phase 1 for pile installation 
or removal to occur at all three locations on the same day and it is 
likely that two or three hammers or a combination of hammers and down-
the-hole (DTH) drills will be used on the same day.

[[Page 675]]

When this occurs, equipment use may be staggered throughout the day, 
and hammer or drill use could occur at times when no other hammer or 
drill is being used. It is also possible that one, two, or three 
hammers, or a combination of up to two DTH drills and an impact or 
vibratory hammer, could coincidentally be in use simultaneously on the 
same or different project components. The likelihood of such an 
occurrence is anticipated to be infrequent and would be for short 
durations on that day. In-water pile installation is an intermittent 
activity, and it is common for installation to start and stop multiple 
times as each pile is adjusted and its progress is measured and 
documented. However, the underwater activities that may affect marine 
mammals, including ESA-listed species, still include only vibratory and 
impact pile installation, vibratory pile removal, and drilling of rock 
sockets. Pile numbers and sizes also remain consistent with the 
information originally provided to NMFS.
Description of In-Water Activities (General to Both Phases)
    Four methods of pile installation are planned. These include use of 
vibratory and impact hammers, DTH drilling of rock sockets, and 
installation of tension anchors at some locations. Most piles will be 
installed vertically (plumb), but some will be installed at an angle 
(battered). Tension anchors will be used to secure some piles to the 
bedrock to withstand uplift forces. Rock sockets will be drilled at 
other locations where overlying sediments are too shallow to adequately 
secure the bottom portion of the pile. Some piles will be seated in 
rock sockets as well as anchored with tension anchors. A vibratory 
hammer will be used to install 44 temporary template piles, no greater 
than 20 inches in diameter, to a depth of 25 feet or less. The total 
duration of vibratory installation and subsequent removal of temporary 
piles will be approximately 22 hours spread over multiple days as shown 
in Table 2, and will take place within the same days as permanent pile 
installation. Installation and removal of temporary piles is therefore 
not anticipated to add to the overall estimated 101 days of pile 
installation and removal for Phase 1 as described in the footnote for 
Table 1.
    The steel sheet piles for the bulkheads are of a Z-shape. Each pile 
is approximately 28 to 30 inches wide, and they interlock together to 
form a continuous wall. These sheet piles will be installed into the 
existing ground at elevations varying from +8 inches to +26 inches mean 
lower low water. Most of this work is expected to be done at lower 
tides so that in-water pile driving work is minimized. However, some 
installation work below the tidal elevations (in water) can be 
expected. The ground where the sheet piles will be installed is 
comprised of existing rubble mound slopes. Some excavation work will be 
needed to temporarily remove the large rocks prior to driving the sheet 
piles.
    Vibratory and Impact Pile-Driving Methods--Installation of steel 
piles through the sediment layer will be done using vibratory or impact 
methods. All piles will be advanced to refusal at bedrock. Where 
sediments are deep and rock socketing or anchoring is not required, the 
final approximately 10 feet of driving will be conducted using an 
impact hammer so that the structural capacity of the pile embedment can 
be verified. Where sediments are shallow, an impact hammer will be used 
to seat the piles into competent bedrock before rock drilling begins. 
The pile installation methods used will depend on sediment depth and 
conditions at each pile location. The sheet pile abutment bulkheads for 
the new Revilla and Gravina ferry berths will be installed using 
vibratory hammer methods. Vibratory and impact pile driving will occur 
during both Phase 1 and Phase 2 of the project (Table 1 and Table 3).
    As shown in Table 1, it is estimated that some piles will require 
50 strikes from the impact hammer and others will require 200 strikes. 
In general, projects on Gravina Island will require approximately 50 
strikes and projects on Revilla Island will require approximately 200 
strikes. These differences are based on sediment characteristics, depth 
to bedrock, and the planned need for further drilling once at bedrock.
    Vibratory Pile Removal--A total of 44 temporary piles will be 
installed and removed during Phase 1 of the project (Table 2), while 12 
piles will be installed and removed during Phase 2 (Table 4). When 
possible, existing piles will be extracted by directly lifting them 
with a crane. A vibratory hammer will be used if necessary to extract 
piles that cannot be directly lifted. Removal of each old pile is 
estimated to require no more than 15 minutes of vibratory hammer use 
for the majority of the piles, but the removal of one 24-inch diameter 
pile may take up to 30 minutes.
    Rock Socket Drilling--Rock sockets are holes drilled into the 
bedrock to advance piles beyond the depth vibratory or impact driving 
methods are able to achieve in softer overlying sediments. The depth of 
the rock socket varies, but 10-15 feet is commonly required. Drilling 
of rock sockets through the bedrock may use both rotary and percussion 
drill mechanisms. Drilling breaks up the rock to allow removal of the 
fragments and insertion of the pile. Drill cuttings are expelled from 
the top of the pile using compressed air. The diameter of the drilled 
rock socket is slightly larger than the pile being driving, and the 
pile is therefore easily advanced in the rock as the hole is drilled. 
It is estimated that drilling rock sockets into the bedrock will take 
about 1-3 hours per pile. Rock sockets will be used in both Phase 1 and 
Phase 2 of the project (Table 1 and 3).
    Tension Anchors--Tension anchors are installed within piles that 
are drilled into the bedrock below the elevation of the pile tip, after 
the pile has been driven through the sediment layer to refusal. A 6- or 
8-inch diameter steel pipe casing is inserted inside the larger 
diameter production pile. A rock drill is inserted into the casing, and 
a 6- to 8-inch-diameter hole is drilled into bedrock with rotary and 
percussion drilling methods. The drilling work is contained within the 
smaller steel pile casing and the larger steel pipe pile. The typical 
depth of the drilled hole varies, but 20-30 feet is common. Rock 
fragments will be removed through the top of the casing with compressed 
air. A steel rod is then grouted into the drilled hole and affixed to 
the top of the pile. The purpose of a rock anchor is to secure the pile 
to the bedrock to withstand uplift forces. Tension anchors will be 
utilized during both Phase 1 and Phase 2 of the project, as shown in 
Table 1 and Table 3.

Phase 1 Project Components

    Each of the four permanent project components in Phase 1 will 
include installation of steel pipe piles that are 18, 24, or 30 inches 
in diameter. Temporary piles installed and removed during Phase 1 to 
support templates for permanent piles will be a maximum of 20 inches in 
diameter. Two of the components (Revilla and Gravina New Ferry Berths) 
will require the installation of steel sheet piles that will comprise 
the bulkhead abutments and are 27.6 or 30.3 inches in width. These 
sheet piles will be installed using vibratory driving at elevations 
varying from +8 inches to +26 inches mean lower low-water. Most of this 
work is expected to be done at lower tides so that in-water pile 
driving work is minimized. However, some installation work below the 
tidal elevations (in water) can be expected. The ground where the sheet 
piles will be installed is comprised of existing rubble mound

[[Page 676]]

slopes. Some excavation work will be needed to temporarily remove the 
large rocks prior to driving the sheet piles.
    The estimated installation and removal rates for Phase 1 are 1.5 
permanent pipe piles per day, 10 permanent sheet piles per day, and 4 
to 6 temporary piles per day. Different types of piles may be installed 
or removed within a day.
    Project components are briefly described below and Table 1 shows 
the number and size of piles broken down by the individual components 
of Phase 1. For additional information on how these piles will be 
configured, and what structures they will make up, please refer to the 
IHA Application.
    Revilla New Ferry Berth and Upland Improvements--The new Revilla 
Island airport shuttle ferry berth will be constructed immediately 
adjacent to the existing Revilla Island Ferry Berth (Figure 1-2 in IHA 
Application). It is the only Phase 1 component that will occur on 
Revilla Island.
    New Gravina Island Shuttle Ferry Berth/Related Terminal 
Improvements--The new Gravina Island airport shuttle ferry berth will 
be constructed immediately adjacent to the existing Gravina Island 
Ferry Berth (Figure 1-2 in IHA Application).
    Gravina Airport Ferry Layup Facility--Improvements to the Gravina 
Island Ferry layup dock facility will occur in the same location as the 
existing layup dock facility (Figure 1-2 in IHA Application). The 
current layup dock is in disrepair and needs to be replaced.
    Gravina Freight Facility--The new Gravina Island heavy freight 
mooring facility will be constructed in the same location as the 
existing barge offload facility (Figure 1-2 in IHA Application). This 
facility will provide improved access to Gravina Island for highway 
loads that cannot be accommodated by the shuttle ferry. Five breasting 
dolphins and one mooring dolphin will be constructed to support barge 
docking and will include pedestrian walkways for access by personnel. 
In addition, two new pile-supported mooring line structures will be 
constructed above the high tide line.

                                Table 1--Pile Details and Estimated Effort Required for Pile Installation During Phase 1
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         Project component                                                                Average
-----------------------------------                                          Average      drilling
                                                  Number of    Number of    vibratory     duration      Impact     Estimated     Average
                                     Number of       rock       tension      duration     for rock   strikes per     total      piles per      Days of
             Pile Type                 piles       sockets      anchors      per pile   sockets per      pile      number of   day (range)  installation
                                                                            (minutes)       pile                     hours
                                                                                         (minutes)
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Revilla New Ferry Berth and Upland
 Improvements:
    24'' Pile Diameter............           65            0           25           30          N/A          200           65    1.5 (1-3)            43
    30'' Pile Diameter............           18            0           14           30          N/A          200           18    1.5 (1-3)            12
    AZ 14-770 Sheet Pile..........           55          N/A          N/A           15          N/A          N/A           14     6 (6-12)             9
New Gravina Island Shuttle Ferry
 Berth/Related Terminal
 Improvements:
    24'' Pile Diameter............           66           52           25           15          120           50          182    1.5 (1-3)            44
    30'' Pile Diameter............            8            4            4           15          180           50            8    1.5 (1-3)             5
    AZ 19-700 Sheet Pile..........         66.6          N/A          N/A           15          N/A          N/A           14     6 (6-12)            12
Gravina Airport Ferry Layup
 Facility:
    18'' Pile Diameter............            3            0            0           15          N/A           50            2    1.5 (1-3)             2
    30'' Pile Diameter............           12           12           10           15          180           50           23    1.5 (1-3)             8
Gravina Freight Facility:
    20'' Pile Diameter............            6            0            6           15          N/A           50            2    1.5 (1-3)             4
    24'' Pile Diameter............            3            3            3           15          120           50            3    1.5 (1-3)             2
    30'' Pile Diameter............            4            2            4           15          180           50           75    1.5 (1-3)             3
                                   ---------------------------------------------------------------------------------------------------------------------
        Phase 1 Total.............          320           73           91  ...........  ...........  ...........  ...........  ...........         * 144
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* This number reflects the number of days that would be required if pile driving only occurred at one location at a time. ADOT&PF expects that multiple
  project components may be constructed simultaneously, reducing the actual number of days of pile driving to 101.


                                     Table 2--Numbers of Temporary Piles To Be Installed and Removed for Each Project Component and Structure During Phase 1
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                                                                  Average vibratory          Average vibratory
        Project component          Number of temporary piles    duration per pile for      duration per pile for      Days of installation         Days of removal            Piles per day
                                                                installation (minutes)       removal (minutes)
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Revilla New Ferry Berth and        12.......................  15.......................  15.......................  2 to 3..................  2 to 3..................  4 to 6.
 Upland Improvements.
New Gravina Island Shuttle Ferry   12.......................  15.......................  15.......................  2 to 3..................  2 to 3..................  4 to 6.
 Berth/Related Terminal
 Improvements.
Gravina Airport Ferry Layup        8........................  15.......................  15.......................  1 to 2..................  0.75 to 2...............  4 to 6.
 Facility.
Gravina Freight Facility.........  12.......................  15.......................  15.......................  2 to 3..................  2 to 3..................  4 to 6.
                                  --------------------------------------------------------------------------------------------------------------------------------------------------------------
    Total........................  44.......................  660 (11 hours)...........  660 (11 hours)...........  7-11....................  7-11.
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Phase 2 Project Components

    The two project components in Phase 2 will include installation of 
steel pipe piles that are 16, 24 and 30 inches in diameter as shown in 
Table 3. Methods for vibratory and impact installation of temporary and 
permanent piles, drilling of rock sockets, and installation of tension 
anchors will be consistent with those described above. The estimated 
installation and removal rate for Phase

[[Page 677]]

2 is between 1.2 to 1.5 pipe piles per day depending on pile size.
    One 24-inch diameter pile will be installed at the existing Revilla 
ferry berth. Fifteen 24-inch diameter piles and eight 30-inch-diameter 
piles will be installed at the existing Gravina ferry berth. A total of 
10 piles will be removed to accommodate upgrades to the existing 
Revilla Island and Gravina Island ferry berths. One 24-inch pile will 
be removed from the floating fender dolphin at the existing Revilla 
ferry berth. The nine 16-inch-diameter piles that support the three 
existing dolphins at the Gravina ferry berth will also be removed. It 
is anticipated that, when possible, existing piles will be extracted by 
directly lifting them with a crane. A vibratory hammer will be used if 
necessary to extract piles that cannot be directly lifted. Installation 
of sheet piles is not planned during Phase 2.
    Revilla Refurbish Existing Ferry Berth Facility--Improvements to 
the existing Revilla Island Ferry Berth will include the following: (1) 
Replace the transfer bridge, (2) replace rubber fender elements and 
fender panels, (3) replace one 24-inch pile on the floating fender 
dolphin, (4) installation of 12 tension anchors and (5) replace the 
bridge float with a concrete or steel float of the same dimensions. 
Construction of the transfer bridge, bridge float, and fender elements 
will occur above water. The only in-water work will be pile 
installation and removal associated with construction of the dolphins. 
No temporary piles will be installed or removed during this component 
of the project.
    Gravina Refurbish Existing Ferry Berth Facility--Improvements to 
the existing Gravina Island Ferry Berth will include the following: (1) 
Replace the transfer bridge, (2) remove the catwalk and dolphins, (3) 
replace the bridge float with a concrete or steel float of the same 
dimensions, (4) construct a floating fender dolphin, and (5) construct 
four new breasting dolphins. Construction of the transfer bridge, 
catwalk, and bridge float will occur above water. The only in-water 
work will be pile installation and removal associated with construction 
of the dolphins. A vibratory hammer will be used to install and remove 
12 temporary template piles, no greater than 20 inches in diameter, to 
a depth of 25 feet or less (Table 4). The total duration of vibratory 
installation and subsequent removal of temporary piles will be 
approximately 6 hours spread over multiple days, and will take place 
within the same days as permanent pile installation. Installation and 
removal of temporary piles is therefore not anticipated to add to the 
overall estimated 27 days of pile installation and removal for Phase 2.

                          Table 3--Pile Details and Estimated Effort Required for Pile Installation and Removal During Phase 2
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         Project component                                                                Average
-----------------------------------                                          Average      drilling
                                                  Number of    Number of    vibratory     duration      Impact     Estimated     Average       Days of
                                     Number of       rock       tension      duration     for rock   strikes per     total      piles per   installation
             Pile Type                 piles       sockets      anchors      per pile   sockets per      pile      number of   day (range)   and removal
                                                                            (minutes)       pile                     hours
                                                                                         (minutes)
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Revilla Refurbish Existing Ferry
 Berth Facility:
    24'' Pile Diameter............            1  ...........  ...........           30  ...........           50            1            1             1
    24'' Pile Diameter (Removal)..            1  ...........  ...........           30  ...........          N/A            1            1             1
Gravina Refurbish Existing Ferry
 Berth Facility:
    24'' Pile Diameter............           15            0  ...........           15  ...........           50           11    1.5 (1-3)            10
    30'' Pile Diameter............            8            3           12           15          180           50            6    1.2 (1-3)             7
    16'' Pile Diameter (Removal)..           12  ...........  ...........           15  ...........  ...........            2    1.5 (1-3)             8
        Phase 2 Total.............          *24            3  ...........  ...........  ...........  ...........  ...........  ...........            27
--------------------------------------------------------------------------------------------------------------------------------------------------------
* (+13 Removal)


                 Table 4--Number of Temporary Piles To Be Installed and Removed for Each Project Component and Structure During Phase 2
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                  Average vibratory    Average vibratory
                                   Number of      duration per pile    duration per pile         Days of
       Project component           temporary      for installation        for removal          installation       Days of removal       Piles per day
                                     piles            (minutes)            (minutes)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Revilla Refurbish Existing                   0  0                     0                    0                    0                    0.
 Ferry Berth Facility.
Gravina Refurbish Existing                  12  15                    15                   2 to 3               2 to 3               4 to 6.
 Ferry Berth Facility.
    Total.....................              12  180 (3 hours) *.....  180 (3 hours)......  2 to 3.............  2 to 3.
--------------------------------------------------------------------------------------------------------------------------------------------------------

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

Comments and Responses

    A notice of NMFS's proposal to issue an IHA to ADOT&PF was 
published in the Federal Register on July 17, 2019 (84 FR 34134). That 
notice described, in detail, ADOT&PF's planned 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 the following comments from the Marine Mammal 
Commission:
    Comment 1: The Commission indicated that NMFS had not included 
tension anchoring when estimating take of marine mammals and also used 
a source level for rock socket drilling that was low compared to a 
report featuring hydroacoustic data collected during anchor 
installation and rock socket

[[Page 678]]

drilling for the White Pass Yukon Route authorization (Reyff and 
Heyvaert 2019).
    Response: There is limited data available regarding sound source 
levels associated with tension anchoring (also known as rock anchor 
drilling) and down-the-hole (DTH) drilling (also known as rock socket 
drilling). Much of the available data are highly variable and feature 
limited sample sizes. The sources also demonstrate characteristics of 
both impulsive and continuous noise sources. These factors influence 
our determination of appropriate Level A harassment and Level B 
harassment isopleths as well as estimated take levels. NMFS' approach 
to assessing potential impacts from tension anchoring or rock socket 
drilling has changed over time as new information becomes available 
regarding potential impacts from tension anchoring or rock socket 
drilling.
    NMFS had assumed that impacts from tension anchoring were 
discountable because the anchoring process does not generate steel-on-
steel drilling noise and because the anchoring noise occurs in 
isolation from the water column. In one instance, NMFS did use JASCO 
sound source verification data from DTH drilling at Kodiak Pier 1. NMFS 
used this to establish a proxy source level of 167.7 dB RMS for rock 
anchor drilling (cited as both Warner and Austin 2016; and Denes et al. 
2016) for the Ketchikan Berth IV Expansion Project IHA (83 FR 37473; 
August 8, 2019). However, rock anchor drilling is different from rock 
socket drilling in that much smaller holes are drilled in the bedrock 
that is well below where rock sockets are drilled. The bedrock is 
overlain with sediments, and will likely attenuate noise production 
from drilling and reduce noise propagation into the water column. 
Additionally, the casing used during drilling is inside the larger 
diameter pile, meaning that there is no steel-on-steel contact, which 
should further reduce noise levels.
    A recent report by Reyff and Heyvaert (2019) recorded a level of 
157 dB RMS for rock anchor drilling near Skagway, AK. The authors noted 
that this report represents a small amount of data, which was highly 
variable, and the conditions at testing sites need to be considered 
before applying the findings to projects at other locations. The 
authors treated rock anchor drilling as a continuous noise and 
calculated that the Level B harassment isopleth was 205 meters. By 
comparison, the calculated distance to the 120 dB rms threshold for 
continuous noise using a source level of 166 dB rms (Denes et al. 2016) 
and 15logR resulted in a Level B harassment zone isopleth of 12,023 
meters. Given the very small Level B harassment zone (205 m) associated 
with measured source level that is 9 dB greater (166 dB vs. 157 dB) 
NMFS has determined that take from rock anchor drilling is 
discountable.
    The Commission further commented that the source value of 166 dB 
RMS used by NMFS for DTH/rock socketing was too low considering that 
Reyff and Heyvaert (2019) reported a value of 179 dB RMS. The value 
used by NMFS was adopted from DTH drilling at Kodiak and represents the 
median from Denes et al. (2016) compared to the average from that study 
(167.7 dB RMS) used for the Ketchikan Berth IV Expansion Project noted 
previously. Additionally, measurements at Kodiak were collected from a 
sample of 8 piles, which constitutes a robust data set while only three 
driving events with highly variable measurements were recorded for rock 
socket drilling by Reyff and Heyvaert (2019). As noted above, the 
calculated distance to the 120 dB rms threshold for continuous noise 
using a source level of 166 dB rms and 15logR resulted in a Level B 
harassment zone isopleth of 12,023 meters for Tongass Narrows. In 
comparison, JASCO calculated the transmission loss coefficient at 
Kodiak as 18.9 with distances of 5,049 meters to the mean and 6,846 
meters to the 90th percentile for the 120 dB threshold. Therefore, the 
sound source level of 166 dB RMS and associated Level B harassment 
isopleth calculated for the Tongass Narrows IHA can be considered 
conservative.
    There is also some uncertainty about whether these sound sources 
should be classified as impulsive or continuous noise sources, since 
they often contain characteristics of both. The classification selected 
would have a significant effect on the size of the resulting Level A 
harassment and Level B harassment zones. Here DTH/rock socketing is 
treated as a continuous noise source because it does not demonstrate 
rapid rise times and decay of sound pressure level that is typical of 
impulsive noises
    For these particular IHAs, NMFS has determined that the potential 
impacts to marine mammals from tension anchoring are discountable. NMFS 
also determined it is appropriate to adopt 166 dB RMS as a proxy for 
DTH/rock socket drilling. NMFS will continue to investigate noise 
characteristics associated with these relatively new pile driving 
technologies. We will also work on the development of guidance that 
could be used by future applicants when submitting applications for 
incidental take authorizations that utilize these methods.
    Comment 2: The Commission recommended that NMFS authorize 
additional take of harbor seals by Level A harassment. Based on Table 1 
of the proposed IHAs, impact pile driving would occur on up to 60 days 
during Phase I and on those days the Level A harassment zones exceed 
100-m shut down zone. Although ADOT&PF would shut down its activities 
if a harbor seal approaches the Level A harassment zones, harbor seals 
could pop up undetected in Level A harassment zones larger than 100 m.
    Response: While seals may appear or enter into the Level A 
harassment zone specified for a given activity, there is only a small 
likelihood that any of those animals would likely remain in the zone 
long enough such that their cumulative exposure could result in 
permanent threshold shift (PTS). Additionally, the anticipated 
effectiveness of the required monitoring and mitigation measures would 
limit the number of seals that experience auditory injury. However, 
NMFS concluded that while take of seals by Level A harassment is 
unlikely, it could occur in limited numbers and, therefore, authorized 
take at a level that reflects this assessment.
    Comment 3: The Commission noted that the Level B harassment takes 
for humpback whales were vastly underestimated based on the method NMFS 
used for other cetaceans for ADOT's proposed authorizations. NMFS used 
the number of months (12) that a species could occur in the area and 
the frequency of occurrence to estimate the numbers of takes for all 
species other than humpback whales. For humpback whales, NMFS divided 
the number of days (144 in the proposed IHA) by the frequency of 
occurrence, which resulted in 82 rather than 204 Level B harassment 
takes of humpback whales for Phase I.
    Response: NMFS frequently calculates authorized take numbers of 
assorted species in different ways. In this case, local anecdotal 
information regarding the presence of humpback whales was presented to 
NMFS in the format of a weekly rate. Take of other species was 
tabulated based on monthly rates. NMFS determined that both methods are 
acceptable and were used appropriately.
    Comment 4: The Commission warned that potential one-year renewals 
of these two authorizations could have unintended consequences. For 
example, if ADOT&PF is unable to complete Phase I activities by March 
2021 and a renewal is necessary, the renewal authorization would 
overlap with the Phase II activities that are to begin in March 2021. 
The Commission asked

[[Page 679]]

whether the Phase II authorization would be reissued for March 2022 to 
March 2023 to eliminate overlap of activities or whether the unfinished 
Phase I activities would occur along with all of the Phase II 
activities as of March 2021. The Commission further recommended that 
NMFS issue a one-year renewal for Phase I activities only if the Phase 
II authorization is delayed until 2022.
    Response: ADOT&PF is planning to employ concurrent driving which 
will decrease the number of driving days from 144 to 101 and expedite 
the completion of Phase 1, reducing the likelihood that a Phase 1 
renewal would be needed.
    The Commission's comment likely reflects concern regarding the 
potential for cumulative impacts or cumulative effects to occur. NMFS 
has determined that the concurrent operation of up to three driving 
devices would result in a negligible impact to affected species. The 
required mitigation and monitoring measures in combination with the 
short duration of any overlapping activities (27 days at most, but 
likely much fewer), would result in potential impacts to marine mammals 
that are both temporary and relatively minor. Further, NMFS does not 
expect that cumulative impacts to marine mammals associated with the 
potential overlap of two IHAs would affect the reproduction or survival 
of any individual marine mammals, let alone annual rates of recruitment 
or survival, either alone or in combination with other past, present, 
or ongoing activities. Additionally, we note two important facts: (1) 
The MMC appears to suggest that if the activities authorized in Phase 1 
overlapped with the activities of Phase 2, then the impacts would 
necessarily be greater--but this is not a justified assumption. While 
some individual(s) could potentially be temporarily exposed to higher 
sound levels in a slightly larger area across a day or several, if that 
happened it would mean that the pile driving would take fewer days to 
complete overall, which could potentially reduce the overall impact to 
the exposed animals; and (2) while it is important to consider 
cumulative impacts in the context of NEPA (which we have), as with any 
two independent IHAs, the small numbers and negligible impact 
determinations are made in the context of the impacts of each of the 
specified activities considered in each of the separate IHAs.
    Comment 5: The Commission recommended that NMFS require all action 
proponents that plan to conduct activities in areas where subsistence 
hunting occurs to contact the relevant Native Alaskan communities and 
entities well in advance of any activities commencing. Additionally, 
NMFS should specify in all related documents announcing proposed 
incidental take authorizations which communities and entities were 
contacted, whether any concerns were conveyed, and whether any 
additional mitigation measures should be implemented. The Commission 
also recommended that NMFS refrain from issuing the authorizations 
until ADOT&PF specifies which Native Alaskan communities and entities 
were contacted, whether any concerns were conveyed, and any additional 
measures that may be required to mitigate any potential conflicts with 
subsistence hunting
    Response: NMFS requires applicants to contact Native Alaskan 
communities if proposed projects are located near subsistence hunting 
areas and likely to affect subsistence resources. However, this project 
does not occur in a known subsistence hunting area. The project area is 
largely developed and features regular marine vessel traffic. ADOT&PF 
plans to provide advance public notice of construction activities to 
reduce construction impacts on local residents, ferry travelers, 
adjacent businesses, and other users of Tongass Narrows and nearby 
areas. This will include notification to local Alaska Native 
communities that may have members who hunt marine mammals for 
subsistence. If any Alaska Native communities express concerns 
regarding project impacts to subsistence hunting of marine mammals, 
further communication with ADOT&PF will take place, including provision 
of any project information, and clarification of any mitigation and 
minimization measures that may reduce potential impacts to marine 
mammals. However, given that NMFS does not anticipate any effects on 
the availability of marine mammals for subsistence uses to result from 
the specified activities because project activities will take place 
within the industrial area of Tongass Narrows immediately adjacent to 
Ketchikan where subsistence activities do not generally occur, there is 
no need to delay issuance of the IHAs.
    Comment 6: The Commission recommended that NMFS publish revised 
proposed authorizations due to the issues described in this Comment 
section prior to the issuance of final authorizations.
    Response: NMFS has consulted with ADOT&PF regarding a number of 
issues brought forth by the Commission. NMFS has addressed all of the 
issues brought forth by the Commission and has determined that the 
publication of revised proposed authorizations is not warranted.
    Comment 7: The Commission recommended that NMFS refrain from using 
the renewal process for ADOT&PF's authorization and limit the IHA 
renewal process to authorizations that are expected to have the lowest 
levels of impacts and require the least complex analysis. The 
Commission also recommended that if NMFS intends to use the renewal 
process frequently or for authorizations that require more complex 
analysis, it should provide the Commission and other reviewers a 30-day 
comment opportunity.
    Response: We appreciate the Commission's input and direct the 
Commission and other readers to our recent response to a similar 
comment, which can be found at 84 FR 52464 (October 2, 2019; 84 FR 
52466).
    Comment 8: The Commission recommended that NMFS authorize the 
incidental taking of marine mammals via a rulemaking rather than 
individual incidental harassment authorizations and authorization 
renewals for activities that are scheduled to last more than one year 
at the outset.
    Response: NMFS and prospective applicants routinely discuss how 
incidental take authorization can be obtained most efficiently in a 
manner that satisfies an applicant's authorization needs. A range of 
factors (e.g. project length, project complexity, planned start date) 
generally dictate whether a rulemaking or IHA would be the most 
appropriate path for a specific scenario. There are likely situations 
where the issuance of more than one IHA is more efficient and 
preferable to a formal rulemaking.
    Comment 9: The Commission recommended that NMFS conduct a more 
thorough review of the applications and Federal Register documents to 
ensure not only accuracy, completeness, and consistency, but also to 
ensure that they are based on best available science, prior to 
submitting them to the Federal Register for public comment.
    Response: NMFS thanks the Commission for its recommendation. NMFS 
makes every effort to review notices thoroughly prior to publication 
and will continue this effort to publish the best possible notice for 
public comment using the best available science.

Changes From the Proposed IHAs to Final IHAs

    As described above, ADOT&PF realized in August 2019 that its 
contracting strategy for this project would likely result in two or 
three

[[Page 680]]

construction sites that could be active at one time during Phase 1, 
although not during Phase 2. The contracting approach does not change 
the construction phasing or the amount or extent of activity completed 
in each phase. The potential for more than one piece of equipment 
(vibratory hammer, impact hammer, and/or DTH drill) to operate within a 
day or simultaneously was not considered in the proposed IHAs published 
on July 17, 2019 (84 FR 34134).
    The extent to which the use of more than one hammer or DTH drill 
could occur within a day or simultaneously is unknown and difficult to 
quantify. Use of more than one hammer for pile installation on the same 
day (whether simultaneous or not) would result in a reduction in the 
total number of days of pile installation by increasing the number of 
piles that can be installed per day. The overall number of days of pile 
installation would decrease with use of two or three pieces of 
equipment. With two pieces of equipment used on 30 percent of 
construction days, the anticipated project duration would be reduced 
from a total of 144 days as described in the proposed IHAs to 101 days 
as described in this document. Take estimates for all species uthorized 
for take, except for Minke whale have been revised and all changes are 
noted in the Estimated Take section. Level B harassment monitoring 
zones have also been established to include concurrent driving 
scenarios. Some of the mitigation and monitoring requirements have also 
been revised as described herein and noted in the Mitigation and the 
Monitoring and Reporting sections. Nonetheless, none of these changes 
affect our negligible impact determinations or small numbers findings 
for any of the affected species or stocks.

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's 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's 
website (https://www.fisheries.noaa.gov/find-species).
    Table 5 lists all species with expected potential for occurrence in 
waters near Ketchikan, Alaska and summarizes information related to the 
species or stock, including regulatory status under the MMPA and ESA 
and potential biological removal (PBR), where known. For taxonomy, we 
follow Committee on Taxonomy (2016). 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's 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's 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's U.S. Alaska SARs (e.g., Muto et al., 2018) except for gray 
whale, which could occur in the project area and is assessed in the 
U.S. Pacific SARs (Carretta et al. 2018). All values presented in Table 
5 are the most recent available at the time of publication and are 
available in the 2018 SARs (Muto et al., 2019, Carretta et al. 2019) 
(available online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/draft-marine-mammal-stock-assessment-reports).

                                              Table 5--Marine Mammals That Could Occur in the Project Area
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                            Stock abundance Nbest,
                                                                                         ESA/ MMPA status;  (CV, Nmin, most recent             Annual M/
             Common name                  Scientific name             MMPA stock          strategic (Y/N)    abundance survey) \2\     PBR       SI \3\
                                                                                                \1\
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                          Order Cetartiodactyla--Cetacea--Superfamily Mysticeti (baleen whales)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Eschrichtiidae:
    Gray Whale......................  Eschrichtius robustus..  Eastern North Pacific..  -, -, N             26,960 (0.05, 25,849,         801        138
                                                                                                             2016).
Family Balaenidae:
    Humpback whale..................  Megaptera novaeangliae.  Central North Pacific..  E, D,Y              10,103 (0.3; 7,890;            83         25
                                                                                                             2006).
    Minke whale.....................  Balaenoptera             Alaska.................  -, N                N.A...................        N.A       N.A.
                                       acutorostrata.
    Fin whale.......................  Balaenoptera physalus..  Northeast Pacific......  E, D, Y             N.A...................        5.1        0.6
--------------------------------------------------------------------------------------------------------------------------------------------------------
                            Order Cetartiodactyla--Cetacea--Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Delphinidae:
    Killer whale....................  Orcinus orca...........  Alaska Resident........  -, N                2,347 (N.A.; 2,347;            24          1
                                                                                                             2012).
                                                               West Coast Transient...  -, N                243 (N.A, 243, 2009)..        2.4          0
                                                               Northern Resident......  -, N                261 (N.A.; 261, 2011..       1.96          0
    Pacific white-sided dolphin.....  Lagenorhynchus           North Pacific..........  -,-; N              26,880 (N.A.; N.A.;          N.A.          0
                                       obliquidens.                                                          1990).
Family Phocoenidae:
    Harbor porpoise.................  Phocoena phocoena......  Southeast Alaska.......  -, Y                975 (0.10; 896; 2012).       8.95         34
    Dall's porpoise.................  Phocoenoides dalli.....  Alaska.................  -, N                83400 (0.097, N.A.,          N.A.         38
                                                                                                             1993).
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                         Order Carnivora--Superfamily Pinnipedia
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Otariidae (eared seals and
 sea lions):
    Steller sea lion................  Eumetopias jubatus.....  Eastern U.S............  -,-, N              41,638 (N.A.; 41,638;       2,498        108
                                                                                                             2015).
Family Phocidae (earless seals):

[[Page 681]]

 
    Harbor seal.....................  Phoca vitulina           Clarence Strait........  -, N                31,634 (N.A.; 29,093;       1,222         41
                                       richardii.                                                            2011).
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Endangered Species Act (ESA) status: Endangered (E), Threatened (T)/MMPA status: Depleted (D). A dash (-) indicates that the species is not listed
  under the ESA or designated as depleted under the MMPA. Under the MMPA, a strategic stock is one for which the level of direct human-caused mortality
  exceeds PBR or which is determined to be declining and likely to be listed under the ESA within the foreseeable future. Any species or stock listed
  under the ESA is automatically designated under the MMPA as depleted and as a strategic stock.
\2\ NMFS marine mammal stock assessment reports online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments assessments. CV is coefficient of variation; Nmin is the minimum estimate of stock abundance. In some cases, CV is not applicable (N.A.).
\3\ These values, found in NMFS's SARs, represent annual levels of human-caused mortality plus serious injury from all sources combined (e.g.,
  commercial fisheries, ship strike). Annual M/SI often cannot be determined precisely and is in some cases presented as a minimum value or range. A CV
  associated with estimated mortality due to commercial fisheries is presented in some cases.

    All species that could potentially occur in the project areas are 
included in Table 5. However, the spatial occurrence of gray whale and 
fin whale is such that take is not expected to occur, and they are not 
discussed further beyond the explanation provided here. Gray whales 
have not been reported by any local experts or recorded in monitoring 
reports and it would be extremely unlikely for a gray whale to enter 
Tongass Narrows or the small portions of Revillagigedo Channel this 
project will impact. Similarly for fin whale, sightings have not been 
reported and it would be unlikely for a fin whale to enter the project 
area as they are generally associated with deeper, offshore waters.
    A detailed description of the species likely to be affected by the 
Tongass Narrows Ferry Terminal Modifications and Improvements project, 
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 
proposed IHAs (84 FR 34134; July 17, 2019). Since that time, we are not 
aware of any changes in the status of these species and stocks; 
therefore, detailed descriptions are not provided here. Please refer to 
that Federal Register document for these descriptions.

Potential Effects of Specified Activities on Marine Mammals and Their 
Habitat

    The effects of underwater noise from ADOT&PF's activities have the 
potential to result in behavioral harassment of marine mammals in the 
vicinity of the action area. The proposed IHAs (84 FR 34134; July 17, 
2019) included a discussion of the effects of anthropogenic noise on 
marine mammals, therefore that information is not repeated here; please 
refer to that Federal Register document for additional information.

Marine Mammal Habitat Effects

    The main impact associated with ADOT&PF's activities would be 
temporarily elevated sound levels and the associated direct effects on 
marine mammals. 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 minor impacts to the immediate substrate during installation 
and removal of piles during the pile driving project. These potential 
effects are discussed in detail in the proposed IHAs (84 FR 34134; July 
17, 2019), therefore that information is not repeated here; please 
refer to that Federal Register document for that information.

Estimated Take

    This section provides an estimate of the number of incidental takes 
that are reasonably expected to occur and, therefore, are authorized 
through these IHAs, which informed both NMFS' consideration of ``small 
numbers'' and the negligible impact determinations.
    Harassment is the only type of take expected to result from these 
activities. Except with respect to certain activities not pertinent 
here, section 3(18) of the MMPA defines ``harassment'' as any act of 
pursuit, torment, or annoyance, which (i) has the potential to injure a 
marine mammal or marine mammal stock in the wild (Level A harassment); 
or (ii) has the potential to disturb a marine mammal or marine mammal 
stock in the wild by causing disruption of behavioral patterns, 
including, but not limited to, migration, breathing, nursing, breeding, 
feeding, or sheltering (Level B harassment).
    Authorized takes would primarily be by Level B harassment, as use 
of the sources (i.e., impact/vibratory pile driving and drilling) has 
the potential to result in disruption of behavioral patterns for 
individual marine mammals and some small amount of temporary threshold 
shift (TTS). There is also some potential for auditory injury (Level A 
harassment) to result, primarily for high frequency species and phocids 
because predicted auditory injury zones are larger than for mid-
frequency species and otariids. Auditory injury is unlikely to occur 
for mid-frequency species and otariids. The required mitigation and 
monitoring measures are expected to minimize the severity of such 
taking to the extent practicable, and result in no take by Level A 
harassment for mysticetes.
    As described previously, no mortality is anticipated or authorized 
for this activity. Below we describe how the take is estimated.
    Generally speaking, we estimate take by considering: (1) Acoustic 
thresholds above which the best available science indicates marine 
mammals will be behaviorally harassed or incur some degree of permanent 
hearing impairment; (2) the area or volume of water that will be 
ensonified above these levels in a day; (3) the density or occurrence 
of marine mammals within these ensonified areas; and (4) and the number 
of days of activities. We note 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). Due to the lack of marine marine mammal 
density data, NMFS relied on local occurrence data and average group 
size to estimate take. Below, we describe the factors considered here 
in more detail and present the calculated take estimates.

Acoustic Thresholds

    Using the best available science, NMFS has developed acoustic 
thresholds that identify the received level of underwater sound above 
which exposed marine mammals would be reasonably expected to be 
behaviorally harassed (equated to Level B

[[Page 682]]

harassment) or to incur PTS of some degree (equated to Level A 
harassment).
    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 we consider Level B 
harassment when exposed to underwater anthropogenic noise above 
received levels of 120 dB re 1 [mu]Pa (rms) (microPascal root mean 
square) for continuous (e.g., vibratory pile-driving, drilling) and 
above received levels of 160 dB re 1 [mu]Pa (rms) for non-explosive 
impulsive (e.g., seismic airguns) or intermittent (e.g., scientific 
sonar) sources. Typically, and especially in cases where PTS is 
predicted, NMFS anticipates that some number of individuals may incur 
TTS. However, it is not necessary to separately quantify those takes, 
as it is very unlikely that an individual marine mammal would be 
exposed at the levels and duration necessary to incur TTS without also 
being exposed to the levels associated with behavioral harassment and, 
therefore, we expect any potential TTS takes to be captured by the 
estimated takes by behavioral harassment.
    Both phases of ADOT&PF's planned activity include the use of 
continuous (vibratory pile driving/removal and drilling) and impulsive 
(impact pile driving) sources and, therefore, both the 120 and 160 dB 
re 1 [mu]Pa (rms) thresholds are applicable.
    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).
    These thresholds are provided in Table 6 below. The references, 
analysis, and methodology used in the development of the thresholds are 
described in NMFS 2018 Technical Guidance, which may be accessed at 
https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance.

                     Table 6--Thresholds Identifying the Onset of Permanent Threshold Shift
----------------------------------------------------------------------------------------------------------------
                                                    PTS onset acoustic thresholds \*\ (received level)
             Hearing group              ------------------------------------------------------------------------
                                                  Impulsive                         Non-impulsive
----------------------------------------------------------------------------------------------------------------
Low-Frequency (LF) Cetaceans...........  Cell 1: Lpk,flat: 219 dB;   Cell 2: LE,LF,24h: 199 dB.
                                          LE,LF,24h: 183 dB.
Mid-Frequency (MF) Cetaceans...........  Cell 3: Lpk,flat: 230 dB;   Cell 4: LE,MF,24h: 198 dB.
                                          LE,MF,24h: 185 dB.
High-Frequency (HF) Cetaceans..........  Cell 5: Lpk,flat: 202 dB;   Cell 6: LE,HF,24h: 173 dB.
                                          LE,HF,24h: 155 dB.
Phocid Pinnipeds (PW) (Underwater).....  Cell 7: Lpk,flat: 218 dB;   Cell 8: LE,PW,24h: 201 dB.
                                          LE,PW,24h: 185 dB.
Otariid Pinnipeds (OW) (Underwater)....  Cell 9: Lpk,flat: 232 dB;   Cell 10: LE,OW,24h: 219 dB.
                                          LE,OW,24h: 203 dB.
----------------------------------------------------------------------------------------------------------------
* Dual metric acoustic thresholds for impulsive sounds: Use whichever results in the largest isopleth for
  calculating PTS onset. If a non-impulsive sound has the potential of exceeding the peak sound pressure level
  thresholds associated with impulsive sounds, these thresholds should also be considered.
Note: Peak sound pressure (Lpk) has a reference value of 1 [mu]Pa, and cumulative sound exposure level (LE) has
  a reference value of 1[micro]Pa\2\s. In this Table, thresholds are abbreviated to reflect American National
  Standards Institute standards (ANSI 2013). However, peak sound pressure is defined by ANSI as incorporating
  frequency weighting, which is not the intent for this Technical Guidance. Hence, the subscript ``flat'' is
  being included to indicate peak sound pressure should be flat weighted or unweighted within the generalized
  hearing range. The subscript associated with cumulative sound exposure level thresholds indicates the
  designated marine mammal auditory weighting function (LF, MF, and HF cetaceans, and PW and OW pinnipeds) and
  that the recommended accumulation period is 24 hours. The cumulative sound exposure level thresholds could be
  exceeded in a multitude of ways (i.e., varying exposure levels and durations, duty cycle). When possible, it
  is valuable for action proponents to indicate the conditions under which these acoustic thresholds will be
  exceeded.

Ensonified Area

    Here, we describe operational and environmental parameters of the 
activity that will feed into identifying the area ensonified above the 
acoustic thresholds, which include source levels and transmission loss 
coefficient.
    The sound field in the project area is the existing background 
noise plus additional construction noise from the project. Marine 
mammals are expected to be affected via sound generated by the primary 
components of the project (i.e., impact pile driving, vibratory pile 
driving, vibratory pile removal, and drilling).
    Vibratory hammers produce constant sound when operating, and 
produce vibrations that liquefy the sediment surrounding the pile, 
allowing it to penetrate to the required seating depth. An impact 
hammer would then generally be used to place the pile at its intended 
depth. The actual durations of each installation method vary depending 
on the type and size of the pile. An impact hammer is a steel device 
that works like a piston, producing a series of independent strikes to 
drive the pile. Impact hammering typically generates the loudest noise 
associated with pile installation.
    In order to calculate distances to the Level A harassment and Level 
B harassment sound thresholds for piles of various sizes being used in 
this project, NMFS used acoustic monitoring data from other locations 
to develop source levels (see Table 7). Note that piles of differing 
sizes have different sound source levels (SSLs).
    Empirical data from recent ADOT&PF sound source verification (SSV) 
studies were used to estimate sound source levels from Ketchikan for 
vibratory and impact driving of 30-inch steel pipe piles and Kodiak for 
drilling (Denes et al. 2016). The source level for rock socket drilling 
was derived from the above mentioned ADOT&PF SSV study at Kodiak, 
Alaska. The reported median source value for drilling was determined to 
be 166 dB rms for all pile types (Denes et al. 2016, Table 72).
    For vibratory driving of 24-inch steel piles, data from a Navy pile 
driving project in the Puget Sound, WA was reviewed (Navy, 2015). From 
this

[[Page 683]]

review, ADOT&PF determined the Navy's suggested source value of 161 dB 
rms was an appropriate proxy source value, and NMFS concurs. Because 
the source value of smaller piles of the same general type (steel in 
this case) are not expected to exceed a larger pile, the same 161 dB 
rms source value was used for 18-inch and 16-inch steel piles. This 
assumption conforms with source values presented in Navy (2015) for a 
project using 16-inch steel piles at Naval Base Kitsap in Bangor, WA.
    For vibratory driving of both 27.6-inch and 30.3-inch sheet piles, 
ADOT&PF used a source level of 160 dB rms. These source levels were 
reported in Caltrans (2015) summary tables for 24-inch steel sheet 
piles, and NMFS concurs that this value was an acceptable proxy.
    Finally, ADOT&PF used source values of 177 dB SEL and 190 dB rms 
for impact driving of 24-inch and 18-inch steel piles. These values 
were determined based on summary values presented in Caltrans (2015) 
for impact driving of 24-inch steel piles. NMFS concurs that the same 
source value was an acceptable proxy for impact driving of 18-inch 
steel piles.

   Table 7--Estimates of Mean Underwater Sound Levels Generated During Vibratory and Impact Pile Installation,
                                      Drilling, and Vibratory Pile Removal
----------------------------------------------------------------------------------------------------------------
 
----------------------------------------------------------------------------------------------------------------
Method and pile type                           Sound source level at 10 meters           Literature source
----------------------------------------------------------------------------------------------------------------
Vibratory Hammer....................                        dB rms
----------------------------------------------------------------------------------------------------------------
30-inch steel piles.................                         162                         Denes et al., 2016,
                                                                                          Table 72.
24-inch steel piles.................                         161                         Navy 2015.
20-inch steel piles.................                         161                         Navy 2015.
18-inch steel piles.................                         161                         Navy 2015.
16-inch steel piles.................                         161                         Navy 2015.
27.6-inch sheet pile................                         160                         Caltrans 2015.
30.3-inch sheet pile................                         160                         Caltrans 2015.
----------------------------------------------------------------------------------------------------------------
Drilling Rock Sockets...............                        dB rms
----------------------------------------------------------------------------------------------------------------
All pile diameters..................                         166                         Denes et al., 2016,
                                                                                          Table 72.
                                     ---------------------------------------------------------------------------
Impact Hammer.......................          dB rms           dB SEL          dB peak
----------------------------------------------------------------------------------------------------------------
30-inch steel piles.................             195              181              209   Denes et al., 2016,
                                                                                          Table 72.
24-inch steel piles.................             190              177              203   Caltrans 2015.
18-inch steel piles.................             190              177              203   Caltrans 2015.
----------------------------------------------------------------------------------------------------------------
Note: It is assumed that noise levels during pile installation and removal are similar. Use of an impact hammer
  will be limited to 5-10 minutes per pile, if necessary. It is assumed that drilling produces the same SSL
  regardless of DTH diameter. SEL = sound exposure level; dB peak = peak sound level; rms = root mean square.

    ADOT&PF plans to employ the simultaneous use of two or more noise 
sources which can create overlapping sound fields that result in 
additive effects of sound from the different hammers under certain 
conditions (NMFS 2018, WSDOT 2019). The combined source levels can be 
calculated using rules of decibel addition described below and shown in 
Table 8. Overlapping sound fields created by use of more than one 
hammer are handled differently for impact and vibratory hammers. The 
use of two impact hammers simultaneously is unlikely to result in the 
two hammers operating in synchrony therefore, the sound pressure levels 
will not be adjusted regardless of the distance between the hammers. In 
this case, each impact hammer will be considered to have its own 
independent harassment zones. Sound from two or more continuous sources 
near the same location results in louder sound levels than from a 
single source. NMFS is treating DTH drilling as a continuous noise 
source for this project and it will be considered a similar noise to 
vibratory hammering. The sound levels from continuous sources cannot be 
added by standard addition because the decibel is measured on a 
logarithmic scale. For example, two sounds of equal level (plus or 
minus 1 dB) combine to raise the sound level by 3 dB. However, if two 
sounds differ by more than 10 dB, there is no combined increase in the 
sound level; the higher output covers any other sound. For marine 
mammal monitoring purposes, if the isopleth from one sound source 
encompasses a second sound source over a free sound field (i.e., no 
landmass separating the sound sources), then the continuous sources are 
considered close enough to be a ``combined sound source'' and their 
sound levels are added (NMFS 2018, WSDOT 2019) to determine the sound 
isopleth. The resulting isopleth is centered on the ``combined 
source,'' which is the geometric centroid of the polygon formed by the 
sound sources.
    For simultaneous use of three or more hammers or DTH drills, the 
three pieces with the highest noise levels must be identified. The same 
rules for decibel addition are then applied to the two lowest source 
levels of the three. The resulting combined source level is then added 
to the third remaining source level using the same rules. For example, 
if two DTH hammers (166 dB rms each) are used simultaneously with 
vibratory installation of a 24-inch pile (161 dB rms), first the two 
lowest levels are added together using the rules of decibel addition: 
166-161 = 5, and therefore 1 dB is added to 166 dB as shown in Table 8, 
resulting in a combined noise level of 167 dB for the two pieces of 
equipment. Then 167 is added to the noise level of the third piece of 
equipment, 166. Since 167-166 is 1, 3 dB are added to 167, resulting in 
a combined noise level for all equipment of 170 dB as shown in Table 8.
    At this stage in project planning, it is difficult to predict when 
or where each of the two or three contractors or construction crews may 
be working, and therefore, is also difficult to predict which 
combinations of activities might occur simultaneously and for how long. 
The Phase 1 sound source levels were calculated for all possible 
combinations of pile installation and removal using two and three 
vibratory hammers and/or two DTH drills and are shown in Tables 9, 10, 
11, and 12. The combined

[[Page 684]]

sound source levels for simultaneous vibratory hammer use, or use of a 
vibratory hammer and DTH drill simultaneously, range from 163 to 170 dB 
rms, depending on the number of piles (two or more) being installed 
simultaneously, pile size and type, and method of installation. These 
source levels were used to establish Level A harassment and Level B 
harassment isopleths. Simultaneous use of three DTH drills was not 
analyzed because it is not anticipated to occur.

            Table 8--Rules for Combining Sound Levels Generated During Pile Installation and Removal
----------------------------------------------------------------------------------------------------------------
                                                                    Level A harassment      Level B harassment
             Hammer types                  Difference in SSL              zones                    zone
----------------------------------------------------------------------------------------------------------------
Vibratory, Impact.....................  Any....................  Use impact zones.......  Use vibratory zone.
Impact, Impact........................  Any....................  Use zones for each pile  Use zone for each pile
                                                                  size and number of       size.
                                                                  strikes.
Vibratory, Vibratory..................  0 or 1 dB..............  Add 3 dB to the higher   Add 3 dB to the higher
                                                                  source level.            source level.
                                        2 or 3 dB..............  Add 2 dB to the higher   Add 2 dB to the higher
                                                                  source level.            source level.
                                        4 to 9 dB..............  Add 1 dB to the higher   Add 1 dB to the higher
                                                                  source level.            source level.
                                        10 dB or more..........  Add 0 dB to the higher   Add 0 dB to the higher
                                                                  source level.            source level.
----------------------------------------------------------------------------------------------------------------
Source: Modified from USDOT 1995, WSDOT 2018, and NMFS 2018.
Note: SSL = sound source level; dB = decibels.

    Simultaneous in-water pile installation and removal will not occur 
during Phase 2 of the Tongass Narrows Project, and therefore this 
possibility was not analyzed. As described in the proposed IHAs, in-
water pile installation and removal on the Revilla Island side of the 
Narrows during Phase 2 will be limited to no more than 2 hours, and, as 
agreed by ADOT&PF, the IHA will require that those 2 hours not coincide 
with in-water pile installation/removal on Gravina Island.
BILLING CODE 3510-22-P

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BILLING CODE 3510-22-C

Level B Harassment Zones

    Transmission loss (TL) is the decrease in acoustic intensity as an 
acoustic pressure wave propagates out from a source. TL parameters vary 
with frequency, temperature, sea conditions, current, source and 
receiver depth, water depth, water chemistry, and bottom composition 
and topography. The general formula for underwater TL is:

TL = B * Log10 (R1/R2),

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

    This formula neglects loss due to scattering and absorption, which 
is assumed to be zero here. The degree to which underwater sound 
propagates away from a sound source is dependent on a variety of 
factors, most notably the water bathymetry and presence or absence of 
reflective or absorptive conditions including in-water structures and 
sediments. Spherical spreading occurs in a perfectly unobstructed 
(free-field) environment not limited by depth or water surface, 
resulting in a 6 dB reduction in sound level for each doubling of 
distance from the source (20*log[range]). Cylindrical spreading occurs 
in an environment in which sound propagation is bounded by the water 
surface and sea bottom, resulting in a reduction of 3 dB in sound level 
for each doubling of distance from the source (10*log[range]). A 
practical spreading value of fifteen is often used under conditions, 
such as at Tongass Narrows, where water generally increases with depth 
as the receiver moves away from pile driving locations, resulting in an 
expected propagation environment that would lie between spherical and 
cylindrical spreading loss conditions.
    Using the practical spreading model, ADOT&PF determined underwater 
noise would fall below the behavioral effects threshold of 120 dB rms 
for marine mammals at a maximum radial distance of 12,023 m for rock 
socket drilling. This distance determines the maximum Level B 
harassment zone for the project. Other activities, including vibratory 
and impact pile driving, will have smaller Level B harassment zones. 
All Level B harassment isopleths are reported in Table 13 and Table 14 
below. It should be noted that based on the geography of Tongass 
Narrows and the surrounding islands, sound will not reach the full 
distance of the Level B harassment isopleth in all directions. 
Generally, due to interaction with land, only a thin slice of the 
possible area is ensonified to the full distance of the Level B 
harassment isopleth.

 Table 13--Calculated Distances to Level B Harassment Isopleths and Ensonified Areas During Pile Installation and Removal of a Single Piece of Equipment
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                            Isopleth--                      Isopleth--                      Isopleth--
                        Pile size                           impact (m)    Impact (km\2\)   vibratory (m)     Vibratory     drilling (m)      Drilling
                                                             (160 dB)                        (120 dB)         (km\2\)        (120 dB)         (km\2\)
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                  Phase 1 Revilla side
--------------------------------------------------------------------------------------------------------------------------------------------------------
24-inch piles...........................................           1,000        0.780348           5,412        3.224297  ..............  ..............
30-inch piles...........................................           2,154        1.504843           6,310        3.584237  ..............  ..............
Sheet pile..............................................  ..............  ..............           4,642        2.856483  ..............  ..............
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                  Phase 1 Gravina side
--------------------------------------------------------------------------------------------------------------------------------------------------------
18-inch.................................................           1,000        1.297393           5,412        9.361061  ..............  ..............
24-inch piles...........................................           1,000        1.297393           5,412        9.361061          12,023       23.618314
30-inch piles...........................................           2,154        3.077801           6,310        11.11939          12,023       23.618314
Sheet pile..............................................  ..............  ..............           4,642        7.712967  ..............  ..............
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                  Phase 2 Revilla side
--------------------------------------------------------------------------------------------------------------------------------------------------------
24-inch.................................................           1,000        0.780348           5,412        3.187212  ..............  ..............
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                  Phase 2 Gravina side
--------------------------------------------------------------------------------------------------------------------------------------------------------
16-inch.................................................  ..............  ..............           5,412         8.03168  ..............  ..............
24-inch piles...........................................           1,000        1.297393           5,412         8.03168  ..............  ..............
30-inch piles...........................................           2,154        3.077801           6,310        9.472484          12,023       23.618314
--------------------------------------------------------------------------------------------------------------------------------------------------------

    The Level B harassment zone distance was determined based on 
calculating the combination of simultaneously installed piles, and 
their resulting combined source level through decibel addition, as 
shown in Table 14. For each combined source level, the Level B 
harassment is consistent, regardless of the combination of equipment. 
Level B harassment zones range from 7,356 meters (vibratory 
installation of two sheet piles or two 24-inch round piles 
simultaneously) to 21,544 meters (drilling for two piles and 
simultaneous vibratory installation of a 30-inch pile).

  Table 14--Level B Harassment Zones for Combinations of Two and Three
        Piles of Different Sizes, Types, and Installation Methods
------------------------------------------------------------------------
                                        Distance to Level B Harassment
         Combined SSL (dB)                    Isopleth (meters)
------------------------------------------------------------------------
                       163                                7,356
                       164                                8,577
                       165                               10,000

[[Page 690]]

 
                       166                               11,659
                       167                               13,594
                       168                               15,849
                       169                               18,478
                       170                               21,544
------------------------------------------------------------------------

    These larger zones are truncated to the southeast by islands, which 
prevent propagation of sound in that direction beyond the confines of 
Tongass Narrows. To the northwest of Tongass Narrows, combined sound 
levels that equal or exceed 167 dB rms extend into Clarence Strait 
before attenuating to sound levels that are presumably below 120 dB 
rms. The maximum size of the ensonified area in Clarence Strait is 21.3 
square kilometers (km\2\), which occurs only when two DTH drills are 
used simultaneously with a vibratory hammer. This value for area is 
used in calculation of exposure estimates for the two species for which 
we have density estimates in Clarence Strait, harbor porpoises and 
Dall's porpoises. This represents the maximum area that could be 
ensonified when multiple pieces of equipment are used, and therefore 
results in a maximum estimate of exposure, because a smaller area is 
ensonified under most equipment combinations.
    In some cases, Level B harassment zones for pile combinations are 
smaller than the Level B harassment zone for DTH drilling with a single 
drill, which is 12,023 meters (Table 14). Only the Level B harassment 
zones for pile combinations equal to or exceeding 167 dB rms extend 
past the 12,023-meter zone analyzed in the proposed IHAs. All 
combinations of two vibratory hammers result in Level B harassment 
zones that are smaller than 12,023 meters in radius (Table 9). To reach 
the 167 dB rms threshold with only vibratory pile installation (no DTH 
drilling), three vibratory hammers would have to simultaneously install 
30-inch piles Table 11). It is possible, but unlikely, that this would 
occur, given that the New Gravina Island Shuttle Ferry Berth/Related 
Terminal Improvements Project includes vibratory installation of only 
eight 30-inch piles for 15 minutes each, or a total of 2 hours of 
vibratory installation; the remaining 66 piles for this project are 24 
inches in diameter.
    ADOT&PF assumes that the 2 hours of simultaneous installation of 
30-inch piles represents 2 days maximum when the Project's Level B 
harassment zone could briefly exceed 12,023 meters. All other 
combinations of three vibratory hammers will have Level B harassment 
zones that are smaller than 12,023 meters in radius and are confined 
within Tongass Narrows, and effects to this area were analyzed in the 
proposed IHAs.
    Combinations of one DTH drill with a vibratory hammer, two DTH 
drills, and two DTH drills with a vibratory hammer also have source 
levels that equal or exceed 167 dB rms (Tables 9, 10, 11, and 12) and 
Level B harassment zones that exceed 12,023 meters (Table 14). No DTH 
drilling will occur during construction on Revilla Island. One or two 
DTH drills could be used for construction of the New Gravina Island 
Shuttle Ferry Berth/Related Terminal Improvements Project and the 
Gravina Freight Facility and Gravina Airport Ferry Layup Facility on 
the same day and/or simultaneously.
    Use of at least one DTH drill simultaneously with a second DTH 
drill or one or two vibratory hammers is the most likely combination of 
multiple pieces of equipment that would result in Level B harassment 
zones that exceed 12,023 meters. It is estimated that construction of 
the New Gravina Island Shuttle Ferry Berth will require the most DTH 
drilling, with an estimated 49 days at a production rate of 1.5 piles 
per day (approximately 180 minutes of DTH drilling per day). On the 
days when DTH drilling occurs, simultaneous use of one or more 
vibratory hammers or a second DTH drill could also occur, resulting in 
a Level B harassment zone that potentially could exceed 12,023 meters 
for a brief period each day.
    In total, the Level B harassment zone could exceed the previously 
analyzed 12,023 meters on up to 51 days (2 days when three 30-inch 
piles are likely to be installed simultaneously plus 49 days when a DTH 
drill could be used in combination with a second DTH drill or vibratory 
hammers, for 51 days total). However, use of multiple pieces of 
equipment, whether simultaneous or on the same day, results in an 
increased production rate as more piles per day are installed. This 
decreases the total number of days of pile installation from 144 to 101 
days (duration of the project) and decreases the number of days when 
the Level B harassment zone size could exceed 12,023 meters.

Level A Harassment Zones

    When the NMFS Technical Guidance (2016) was published, in 
recognition of the fact that ensonified area/volume could be more 
technically challenging to predict because of the duration component in 
the new thresholds, we developed a User Spreadsheet that includes tools 
to help predict a simple isopleth that can be used in conjunction with 
marine mammal density or occurrence to help predict takes. We note that 
because of some of the assumptions included in the methods used for 
these tools, we anticipate that isopleths produced are typically going 
to be overestimates of some degree, which may result in some degree of 
overestimate of take by Level A harassment. 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 
impact/vibratory pile driving or drilling, the NMFS User Spreadsheet 
predicts the closest distance at which, if a marine mammal remained at 
that distance the whole duration of the activity, it would not incur 
PTS. Inputs used in the User Spreadsheet, and the resulting isopleths 
are reported below (Table 15).
    Level A harassment thresholds for impulsive sound sources (impact 
pile driving) are defined for both SELcum and Peak SPL with the 
threshold that results in the largest modeled isopleth for each marine 
mammal hearing group used to establish the Level A harassment isopleth. 
In this project, Level A harassment isopleths based on SELcum were 
always larger than those based on Peak SPL. It should be noted that 
there is a duration component when calculating the Level A harassment 
isopleth based on SELcum, and this duration depends on the number of 
piles that will be driven in a day and strikes per pile. For some 
activities, ADOT&PF plans to drive variable numbers of piles per day 
throughout the project and determine at the beginning of each pile 
driving day, how many piles will be driven that day. Here, this 
flexibility has been accounted for by modeling multiple durations for 
the activity, and determining the relevant isopleths as shown in Table 
17.

[[Page 691]]



                                                         Table 15--Single Pile Driving and Drilling Activity Inputs for User Spreadsheet
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
        Equipment type           Vibratory pile   Vibratory pile  Vibratory pile  Vibratory pile  Vibratory pile  Vibratory pile    Impact pile     Impact pile     Impact pile     Rock socket
-------------------------------     removal           driver          driver          driver          driver          driver       driver  (30-    driver  (24-    driver  (18-      drilling
                               -----------------  (installation    (installation   (installation   (installation   (installation    inch steel      inch steel      inch steel   ---------------
                                                 of sheet piles)    of 30-inch      of 24-inch      of 20-inch      of 18-inch        piles)          piles)          piles)
                                                -----------------  steel piles)    steel piles)    steel piles)    steel piles)  ------------------------------------------------
     Spreadsheet tab used        A.1) Vibratory                  ----------------------------------------------------------------                                                   E.1) Impact
                                  pile driving    A.1) Vibratory  A.1) Vibratory  A.1) Vibratory  A.1) Vibratory  A.1) Vibratory    E.1) Impact     E.1) Impact     E.1) Impact    pile driving
                                                   pile driving    pile driving    pile driving    pile driving    pile driving    pile driving    pile driving    pile driving
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Source Level..................  161 SPL........  160 SPL........  162 SPL.......  161 SPL.......  161 SPL.......  161 SPL.......  181 SEL.......  177 SEL.......  177 SEL.......  166 SPL.
Weighting Factor Adjustment     2.5............  2.5............  2.5...........  2.5...........  2.5...........  2.5...........  2.............  2.............  2.............  2.5.
 (kHz).
(a) Activity duration (hours)   (a) 2.5 24-in    (a) 2.5 (15      (a) 1.5 3 * 30  (a) 1.5 3 * 30  (a) 0.75 3 *    (a) 0.75 3 *    (b) 200 or 50   (b) 200 or 50   (b) 50 (c) 1    (a) 9 or 6.*
 within 24 hours.                pile 30 min/16-  mins * 10).      mins.           mins.           15 mins.        15 mins.        (c) 1 to 3.     (c) 1 to 3.     to 3.
(b) Number of strikes per pile   in 15 min.
(c) Number of piles per day...
Propagation (xLogR)...........  15.............  15.............  15............  15............  15............  15............  15............  15............  15............  15.
Distance of source level        10.............  10.............  10............  10............  10............  10............  10............  10............  10............  10.
 measurement (meters) *.
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
* Duration estimates for rock socket drilling are based on assumption of drilling 3 rock sockets per day. 9 hours would be the estimated duration for drilling related to 30-inch piles, and 6
  hours would be the duration for drilling related to 24- and 18-inch piles.
** For specifics of what number of strikes and number of piles will be used in a given situation, please refer to Table 1 and Table 3.


                           Table 16--Calculated Distances to Level A Harassment Isopleths During Pile Installation and Removal
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                     Piles          Level A harassment isopleth distance  (meters)
                                                                                   installed -----------------------------------------------------------
             Activity                  Pile diameter(s)     Minutes per pile or       or                   Cetaceans                     Pinnipeds
                                                              strikes per pile      removed  -----------------------------------------------------------
                                                                                    per day       LF          MF          HF          PW          OW
--------------------------------------------------------------------------------------------------------------------------------------------------------
Vibratory Installation............  30-inch..............  30 Minutes...........           3          11          <1          15           6          <1
                                    24-inch, 20-inch, 18-  15-30 Minutes........           3           9          <1          13           5          <1
                                     inch.
                                    27.6-inch sheet pile,  15 Minutes...........          12          13           2          18           8           1
                                     30.3-inch sheet pile.
Vibratory Removal.................  24-inch, 16-inch.....  30 Minutes...........           5          13           1          19           8          <1
Drilling Rock Sockets.............  30-inch..............  180 Minutes..........           3          66           6          97          40           3
                                    24-inch, 18-inch.....  120 Minutes..........           3          50           4          74          30           2
Impact Installation...............  30-inch..............  50 Strikes...........           3         208           8         247         111           9
                                                           50 Strikes...........           2         159           6         189          85           7
                                                           50 Strikes...........           1         100           4         119          54           4
                                                           200 Strikes..........           3         523          19         623         280          21
                                                           200 Strikes..........           2         399          15         476         214          16
                                                           200 Strikes..........           1         252           9         300         135          10
Impact Installation...............  24-inch..............  50 Strikes...........           3         113           4         134          61           5
                                                           50 Strikes...........           2          86           3         102          46           4
                                                           50 Strikes...........           1          54           2          65          29           3
                                                           200 Strikes..........           3         283          11         337         152          11
                                                           200 Strikes..........           2         216           8         258         116           9
                                                           200 Strikes..........           1         136           5         162          73           6
Impact Installation...............  18-inch..............  50 Strikes...........           3         113           4         134          61           5
                                                           50 Strikes...........           2          86           3         102          46           4
                                                           50 Strikes...........           1          54           2          65          29           3
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note: A 10-meter shutdown zone will be implemented for all species and activity types to prevent direct injury of marine mammals.

    To keep the analysis simple, ADOT&PF and NMFS analyzed the highest 
source levels for the longest durations of pile installation that could 
occur within a day. For example, if seventeen 30-inch piles were 
installed with a vibratory hammer on a single day, the Level A 
harassment zone for all functional hearing groups would remain smaller 
than 50 meters. Only on the eighteenth 30-inch pile would the isopleth 
for high-frequency cetaceans exceed 50 meters. Similarly, the combined 
source level for vibratory installation of three 30-inch piles is 167 
dB rms (Table 11). The Level A harassment zone for this source level is 
reached when the duration exceeds 155 minutes (2.6 hours). Only after 
470 minutes (7.8 hours) of simultaneous installation of three 30-inch 
piles would the Level A harassment zone reach 100 meters, a production 
rate that is unlikely to be met or exceeded.
    If two DTH drills operated within a day, 5 piles could be installed 
with 115 minutes of DTH drilling for each (575 minutes or 9.5 total 
hours), and the Level A harassment zone for all functional hearing 
groups would remain below 100 meters. Two DTH drills operating 
simultaneously would have a combined source level of 169 dB rms (Table 
9); the Level A harassment zone for this source level is reached when 
the duration exceeds 148 minutes (4.9 hours) of simultaneous use of two 
DTH drills, a production rate that is also unlikely to be met or 
exceeded.

[[Page 692]]



            Table 17--Pile Driving and Drilling Activity Inputs for User Spreadsheet Resulting in Less Than 100-m Level A Harassment Isopleth
--------------------------------------------------------------------------------------------------------------------------------------------------------
          Equipment type             30-inch vibratory maximum    30-inch vibratory, 3 piles     2 DTH drills  (concurrent     DTH drill maximum  (non-
----------------------------------        (non-concurrent          (concurrent installation)           installation)           concurrent installation)
                                           installation)        ----------------------------------------------------------------------------------------
       Spreadsheet Tab Used       ------------------------------
                                    A.1) Vibratory Pile Driving   A.1) Vibratory Pile Driving   A.1) Vibratory Pile Driving  A.1) Vibratory Pile Driving
--------------------------------------------------------------------------------------------------------------------------------------------------------
Source Level.....................  162                           167                           169 SPL                       166 SPL.
Weighting Factor Adjustment (kHz)  2.5                           2.5                           2.5                           2.5.
(a) Activity duration (hours)      (a) 8.5; (b) 17               (a) 7.8; (b) 3                (a) 4.9 (b) 2                 (a) 9.5 (b) 5.
 within 24 hours.
(b) Number of piles per day......
Propagation (xLogR)..............  15                            15                            15                            15.
Distance of source level           10                            10                            10                            10.
 measurement (meters) *.
--------------------------------------------------------------------------------------------------------------------------------------------------------


                 Table 18--Maximum Calculated distances to Level A Harassment Isopleths During Concurrent Pile Installation and Removal
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                          Level A harassment isopleth distance  (meters)
                                                              Time of    -------------------------------------------------------------------------------
                        Activity                           installation                      Cetaceans                               Pinnipeds
                                                              per day    -------------------------------------------------------------------------------
                                                              (hours)           LF              MF              HF              PW              OW
--------------------------------------------------------------------------------------------------------------------------------------------------------
30-inch Vibratory Maximum (non-concurrent installation).             8.5              33               3              49              20               2
2 DTH (concurrent)......................................         \1\ 4.9              67             6.0             100              41               3
30-inch vibratory, 3 piles (concurrent).................         \2\ 7.8              68               6             100              41               3
DTH Maximum (non-concurrent installation)...............         \3\ 9.5              64               6              98              40               3
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Hours of simultaneous installation with 2 DTH drills*.
\2\ Hours of simultaneous installation of 3 30-inch piles**.
\3\ Hours of installation with 2 DTH drills non-concurrent installation (cannot exceed 3 piles or 10 hours per day without being concurrent)

    The scenarios evaluated above and depicted in Table 17 and Table 18 
represent levels of efficiency (production rates) that are unlikely to 
be achieved in the field, and Level A harassment zones for all 
functional hearing groups remained below 100 meters in all cases 
presented above.

Marine Mammal Occurrence and Take Calculation and Estimation

    In this section we provide the information about the presence, 
density, or group dynamics of marine mammals that will inform the take 
calculations. ADOT&PF relied on a synthesis of qualitative information 
from local people, including biologists and the harbormaster, because 
of the lack of small-scale, site-specific species density or abundance 
information for Tongass Narrows and nearby areas. Quantitative 
estimates of exposure were calculated using this qualitative 
information and are therefore not dependent on harassment zone sizes.
    It is important to remember that Level B harassment zone sizes do 
not increase with use of multiple hammers or DTH drills within a day, 
and no additional Level B harassment exposures of marine mammals are 
anticipated to result from use of multiple pieces of equipment within a 
day. As discussed above, no additional exposures are anticipated to 
result from combinations of an impact hammer and a continuous noise 
source (vibratory hammer or DTH drill), because those zones are 
encompassed within the area of ensonification analyzed previously. 
Similarly, no additional exposures are anticipated to result due to 
combinations of impact hammers.
    However, zones sizes that result from a combination of equipment 
that reaches a noise level of 167 dB rms or more (Tables 9, 10, 11, and 
12) extend to the northeast of Tongass Narrows and into Clarence 
Strait, an area that was not considered ensonified under earlier 
construction scenarios analyzed in the proposed IHAs. The revised 
exposures estimates below are based on the simultaneous use of two or 
more vibratory hammers or DTH drills in combinations that exceed 167 dB 
rms.
    ADOT&PF used 51 days as the estimated number of days when the 
12,023-meter Level B harassment zone isopleth could be exceeded and 
exposure or take of marine mammals could occur in Clarence Strait. The 
total number of days of in-water pile installation and removal is now 
estimated at 101 days (instead of 144 days), a reduction of 43 days.
    For most marine mammal species, abundance in Tongass Narrows is 
anticipated to be greater than abundance in Clarence Strait, and the 
reduction in days of ensonification in Tongass Narrows negates the 
increase in area in Clarence Strait. This is especially the case for 
species that have higher abundance in nearshore and shallow waters, and 
less so for species that regularly occur in deeper, more open waters. 
It is anticipated that the ensonified area that extends into Clarence 
Strait will be temporary and intermittent, lasting only for a few 
minutes up to a few hours per day.
Steller Sea Lion
    Steller sea lion abundance in the Tongass Narrows area is not well 
known. No systematic studies of Steller sea lions have been conducted 
in or near the Tongass Narrows area. Steller sea lions are known to 
occur year-round and local residents report observing Steller sea lions 
about once or twice per week (based on communication outlined in 
Section 3 of the IHA application). Abundance appears to increase during 
herring runs (March to May) and salmon runs (July to

[[Page 693]]

September). Group sizes are generally 6 to 10 individuals (Freitag 2017 
as cited in 83 FR 37473) but have been reported to reach 80 animals 
(HDR 2003). Tongass Narrows represents an area of high anthropogenic 
activity that sea lions would normally avoid, but at least three 
seafood processing plants and two fish hatcheries may be attractants to 
these opportunistic scavengers and predators. Sea lions are generally 
unafraid of humans when food sources are available. For these reasons, 
NMFS proposed one group of 10 Steller sea lions may be present in the 
project area each day, but this occurrence rate may as much as double 
(20 Steller sea lions per day) during periods of increased abundance 
associated with the herring and salmon runs (March to May and July to 
September).
    For Phase 1, we anticipate that one large group (10 individuals) 
may be present in the Level B harassment zone once per day. However, as 
discussed above, we anticipate that exposure may be as much as twice 
this rate during March, April, May, July, August, and September, due to 
the increased presence of prey during periods of increased abundance 
(i.e. herring and salmon). Therefore, we expect that two large groups 
(20 individuals) may be present in the Level B harassment zone each day 
during these months (approximately half of Phase 1). We estimate a 
total of 1,515 potential exposures of Steller sea lions (i.e., one 
group of 10 sea lions per day x 50.5 days [or half of Phase 1] + two 
groups of 10 sea lions per day x 50.5 days = 1,515 sea lions) in 
Tongass Narrows.
    Steller sea lions are known to swim across Clarence Strait and to 
use offshore areas with deeper waters, although no estimates of at-sea 
density or abundance in Clarence Strait are available. We estimate that 
a large group of 10 animals may occur in the ensonified portion of 
Clarence Strait each day (one group of 10 sea lions per day x 51 days = 
510 individuals). Therefore, NMFS has authorized the take of 2,025 
individuals (1,515 + 510 = 2,025 individuals) by Level B harassment in 
Tongass Narrows and Clarence Strait. This is a decrease from the 2,160 
takes by Level B harassment proposed to be authorized in the proposed 
IHAs as concurrent driving reduced the number of anticipated driving 
days.
    Take by Level A harassment is not expected for Steller sea lions in 
Phase 1, because of the small Level A harassment zones for otarrids 
(Table 16) and the expected effectiveness of the monitoring and 
mitigation measures discussed below.
    During Phase 2, we anticipate Steller sea lions would be exposed at 
the same rate as during Phase 1. Phase 2 construction is planned to 
occur in the months of April, May and June. Therefore, we expect that 
one large group (10 individuals) may be present in the Level B 
harassment zone once per day for 9 days in June, with an increase to 2 
large groups per day when fish runs occur for 9 days each month in 
April and May. Therefore, NMFS has authorized the take of 450 Steller 
sea lions by Level B harassment (i.e., 1 group of 10 sea lions per day 
x 9 days in June + 2 groups of 10 sea lions per day x 9 days per month 
in both April and May = 450 sea lions) which is the same number of 
takes estimated in the proposed IHAs.
    Take by Level A harassment is not expected for Steller sea lions in 
Phase 2, because of the small Level A harassment zones for otarrids 
(Table 16) and the expected effectiveness of the monitoring and 
mitigation measures discussed below.
Harbor Seal
    Harbor seal densities in the Tongass Narrows area are not well 
known. No systematic studies of harbor seals have been conducted in or 
near Tongass Narrows. They are known to occur year-round with little 
seasonal variation in abundance (Freitag 2017 as cited in 83 FR 37473) 
and local experts estimate that there are about 1 to 3 harbor seals in 
Tongass Narrows every day, in addition to those that congregate near 
the seafood processing plants and fish hatcheries. Based on this 
knowledge, the expected maximum group size in Tongass Narrows is three 
individuals. Harbor seals are known to be curious and may approach 
novel activity. For these reasons we conservatively estimate that up to 
two groups of 3 harbor seals per group could be exposed to project-
related underwater noise each day. Additionally, a smaller number of 
harbor seals could occasionally be present in the Level A harassment 
(PTS) zone and exposed to sound levels for a duration expected to 
result in take by Level A harassment. To account for these uncommon 
instances, ADOT&PF assumed and NMFS agrees that the equivalent of six 
groups of three individuals may be exposed in the Level A harassment 
zone during the whole of Phase 1, and the equivalent of three groups of 
three individuals may be exposed during the whole of Phase 2. Because 
of the nature of take by Level A harassment (small zone size, factoring 
in duration of exposure) and possibility for a marine mammal group to 
be spread over a relatively large area compared to the Level A 
harassment zone, take by Level A harassment will likely not occur to an 
entire group at once. Despite being expected to occur on an individual 
basis, these group size estimates still serve as the basis for take 
estimation for harbor seals.
    During Phase 1, ADOT&PF and NMFS anticipate that two groups of 3 
individuals (6 individuals) could be present in the Level B harassment 
zone once per day, for a total of 606 harbor seals (i.e., 6 individuals 
per day x 101 days = 606 seals) exposed in Tongass Narrows.
    Harbor seals are known to swim across Clarence Strait, although no 
estimates of at-sea density or abundance are available. It is likely 
that harbor seal abundance in Clarence Strait is lower than in Tongass 
Narrows, as harbor seals generally prefer nearshore waters. ADOT&PF and 
NMFS assumed that abundance of harbor seals in Clarence Strait is 5 
individuals per day for a potential exposure of 255 harbor seals (5 
harbor seals per day x 51 days = 255 individuals). Therefore, NMFS has 
authorized the take of 861 individuals by Level B harassment (606 + 255 
= 861 individuals). This represents a slight increase in the number of 
takes estimated and proposed to be authorized in the proposed IHAs 
(846).
    During Phase 1, it is possible, but unlikely, that harbor seals may 
be exposed to sound levels in the Level A harassment zone for a 
duration expected to result in take. As described above NMFS is 
authorizing take by Level A harassment for the equivalent of six groups 
(18 individuals) during Phase 1. This is the same number of takes 
estimated and proposed to be authorized in the proposed IHAs.
    During Phase 2, ADOT&PF and NMFS anticipate that two groups of 3 
individuals could be present in the Level B harassment zone once per 
day for a total of 162 takes of harbor seals by Level B harassment 
(i.e., 6 individuals per day x 27 days = 162 seals). Therefore, NMFS 
has authorized the take of 162 individuals by Level B harassment, which 
is identical to the number estimated in the proposed IHAs.
    During Phase 2, ADOT&PF and NMFS conservatively anticipate that the 
equivalent of three groups of 3 individuals may be present in the Level 
A harassment zone long enough to experience injury without detection by 
Protected Species Observers (PSOs). Therefore, NMFS is authorizing take 
by Level A harassment of 9 harbor seals during Phase 2. This is the 
same number estimated in the proposed IHAs.

[[Page 694]]

Harbor Porpoise
    Harbor porpoises are non-migratory; therefore, our occurrence 
estimates are not dependent on season. Freitag (2017 as cited in 83 FR 
37473) observed harbor porpoises in Tongass Narrows zero to one time 
per month. Harbor porpoises observed in the project vicinity typically 
occur in groups of one to five animals with an estimated maximum group 
size of eight animals (83 FR 37473, August 1, 2018, Solstice 2018). For 
this take estimate, we are considering a group to consist of five 
animals, a value on the high end of the typical group size. Based on 
Freitag (2017), and supported by the reports of knowledgeable locals as 
described in the application, ADOT&PF and NMFS estimated that during 
Phase 1 two groups of 5 harbor porpoises could be exposed to project-
related underwater noise above the Level B harassment threshold each 
month for a total of 90 harbor porpoises (i.e., two groups of 5 per 
month x 9 months = 90 harbor porpoises). Nine months was assumed 
instead of the 12 months used in the proposed IHAs to reflect the 30 
percent reduction in construction duration due to concurrent 
installation.
    Additionally, harbor porpoises may rarely enter the applicable 
Level A harassment zone and be exposed to sound levels for a duration 
expected to result in take by Level A harassment, necessitating 
authorized take by Level A harassment.
    Harbor porpoises are known to swim across Clarence Strait and to 
use other areas of deep, open waters. Dahlheim et al. (2015) estimated 
a density of 0.02 harbor porpoises/km\2\ in an area that encompasses 
Clarence Strait, resulting in an estimate of 22 harbor porpoises (0.02 
harbor porpoises/km\2\ x 21.3 km\2\ x 51 days = 21.7 harbor porpoises, 
rounded up to 22 individuals) that could be potentially exposed to 
project noise resulting in Level B harassment in that area. This 
estimate is likely high, given that the entire 21.3 km\2\ area will 
rarely be ensonified.
    NMFS, therefore, has authorized 112 harbor porpoise takes by Level 
B harassment (90 + 22 = 112 individuals) during Phase 1. In the 
proposed IHAs we had estimated and proposed to authorize 105 takes.
    During Phase 1, we anticipate that 5 individuals (the equivalent of 
one group) may enter the Level A harassment zone undetected, and be 
exposed to sound levels for a duration expected to result in take by 
Level A harassment, approximately once during every 4 months of 
construction, for a total of 15 potential takes by Level A harassment. 
This is the same number estimated and proposed to be authorized in the 
proposed IHAs.
    During Phase 2, NMFS estimates that two groups of harbor porpoises 
may be present in the Level B harassment zone each month. Therefore, 
NMFS has authorized a total of 30 takes by Level B harassment (i.e., 2 
groups of 5 per month x 3 months = 30 harbor porpoises) during Phase 2. 
This is the identical to the number estimated in the proposed IHAs.
    During Phase 2, we anticipate that the equivalent of two groups of 
5 individuals may enter the Level A harassment zone undetected, and be 
exposed to sound levels for a duration expected to result in take by 
Level A harassment, during the 3 months of construction. Therefore, 
NMFS has authorized 10 takes of harbor porpoise by Level A harassment 
which is also the same as the number in the proposed IHAs.
Dall's Porpoise
    Dall's porpoises are expected to only occur in Tongass Narrows a 
few times per year. Their relative rarity is supported by Jefferson et 
al.'s (2019) presentation of historical survey data showing very few 
sightings in the Ketchikan area and conclusion that Dall's porpoise 
generally are rare in narrow waterways, like the Tongass Narrows. 
During Phase 1 in Tongass Narrows, we estimate that 135 Dall's 
porpoises could be present in the Level B harassment zone (i.e., 15 
individuals per month x 9 months of construction = 135 total potential 
exposures).
    This species is more likely to occur in the waters of Clarence 
Strait, however, and the estimate of exposure for this species has 
increased in association with ensonification of that area. Jefferson et 
al. (2019) estimated an average density of 0.19 Dall's porpoises/km\2\ 
in Southeast Alaska, resulting in an estimate of 207 Dall's porpoises 
(0.19 Dall's porpoises/km\2\ x 21.3 km\2\ x 51 days = 207 Dall's 
porpoises) that could be potentially exposed to project noise in that 
area resulting in Level B harassment. NMFS has therefore authorized 342 
takes (135 + 207 = 342) of Dall's porpoise by Level B harassment during 
Phase 1. This is an increase from the 165 takes estimated and proposed 
to be authorized in the proposed IHAs.
    Additionally Dall's porpoises may rarely be present in the 
applicable Level A harassment zone and be exposed to sound levels for a 
duration expected to result in take by Level A harassment. To account 
for this rare circumstance, ADOT&PF assumed and NMFS concurred that the 
equivalent of one group of 15 individuals may be exposed to sound 
levels in the Level A harassment zone for a duration expected to result 
in take during the whole of Phase 1. Therefore, NMFS has authorized 15 
takes by Level A harassment, which is the same number that was 
estimated and proposed to be authorized in the proposed IHAs.
    NMFS has authorized takes during Phase 2 that are identical to what 
was proposed to be authorized in the proposed IHAs. ADOT&PF estimated, 
and NMFS concurs, that 45 Dall's porpoises could be present in the 
Level B harassment zone (i.e., 15 individuals per month x 3 months of 
construction = 45 takes by Level B harassment). ADOT&PF also estimated 
that the equivalent of one group of 15 individuals may be exposed to 
sound levels in the Level A harassment zone for a duration expected to 
result in take, resulting in take by Level A harassment of 15 
individual Dall's porpoises. NMFS concurs with these estimates and has 
authorized take of 45 porpoises by Level B harassment and 15 porpoises 
by Level A harassment. These estimates are the same as those found in 
the proposed IHAs.
Pacific White-Sided Dolphin
    Pacific white-sided dolphins do not generally occur in the shallow, 
inland waterways of Southeast Alaska. There are no records of this 
species occurring in Tongass Narrows, and it is uncommon for 
individuals to occur in the project area. However, historical sightings 
in nearby areas (Dahlheim and Towell 1994; Muto et al. 2018) and recent 
fluctuations in distribution and abundance mean it is possible the 
species could be present. To account for the possibility that this 
species may be present in the project area, NMFS conservatively 
estimated in the proposed IHAs that one large group (92 individuals) of 
dolphins may experience take by Level B harassment in Tongass Narrows 
during each phase of the activity. Pacific white-sided dolphins are 
uncommon in the Clarence Strait area and have not been observed for a 
few years; therefore, there is no change from the original proposed 
numbers of Pacific white-sided dolphins takes.
    NMFS has therefore authorized 92 dolphin takes by Level B 
harassment for both Phase 1 and Phase 2.
    Take by Level A harassment is not expected for Pacific white-sided 
dolphins in Phase 1 or Phase 2 because of the small Level A harassment 
zones for mid-frequency cetaceans and the expected effectiveness of the 
monitoring and mitigation measures discussed below.

[[Page 695]]

Killer Whale
    Killer whales are observed in Tongass Narrows irregularly with 
peaks in abundance between May and July. A previous incidental take 
authorization in the Ketchikan area estimated killer whale occurrence 
in Tongass Narrows at one pod per month (Freitag 2017 as cited in 83 FR 
37473). During Phase 1, ADOT&PF and NMFS estimate that one pod of 12 
individuals may be present and exposed to project-related underwater 
noise at or above the Level B harassment threshold every month except 
between May and July, when two pods of 12 individuals may be present 
and exposed. This methodology was applied to both Tongass Narrows and 
Clarence Strait areas. It is also likely that any animals moving 
through Tongass Narrows would likely be the same animals that use 
Clarence Strait.
    Therefore, NMFS has authorized 144 killer whale takes by Level B 
harassment (12 exposures per month x 6 months + 24 exposures per month 
x 3 months = 144 killer whales). The authorized number of takes is less 
than the 180 takes estimated and proposed to be authorized in the 
proposed IHAs since pile driving activities will now occur over a 
shorter time period.
    During Phase 2, we anticipate that construction would occur in 
April, May, and June. Therefore, NMFS has authorized 60 takes of killer 
whale by Level B harassment (i.e., 12 exposures per month x 1 month 
(April) + 24 exposures per month x 2 months (May, June). There were 96 
takes by Level B harassment estimated in the proposed IHAs. However, 
this figure was incorrect due to a mathematical error. The correct 
number should have been 60 takes.
    Take by Level A harassment is not expected for killer whales in 
either Phase 1 or Phase 2, because of the small Level A harassment 
zones for mid-frequency cetaceans and the expected effectiveness of the 
monitoring and mitigation measures discussed below.
Humpback Whale
    Humpback whales have been observed about once per week, on average, 
in Tongass Narrows according to local reports. Based on the estimated 
occurrence rate of one group of two individuals twice each week and an 
anticipated timeframe of pile driving to occur over the course of 144 
days, NMFS proposed to authorize take of 82 humpback whales in the 
proposed IHAs. NMFS has used this same methodology in the final IHA to 
calculate that 58 (14.4 weeks x 2 groups x 2 animals/week) humpback 
whales could be exposed to project noise in Tongass Narrows over the 
anticipated 101 days of pile installation.
    Local specialists agreed that about four humpback whales could pass 
through or near the ensonified area in Clarence Strait each day. This 
could result in up to 204 additional exposures of humpback whales (4 
humpback whales x 51 days = 204 individuals). Therefore, NMFS has 
authorized take of 262 humpback whales by Level B harassment (204 + 58 
= 262 humpback whales). This represents an increase of the 82 whales 
estimated in the proposed IHAs. Of the 262 humpback whales potentially 
exposed, an estimated 6.1 percent or 16 individuals (262 x 0.061 = 
15.98, rounded up to 16 whales) could be from the ESA-listed Mexico 
Distinct Population Segment (DPS) of humpback whales based on the 
estimated proportion of humpback whales in Southeast Alaska that belong 
to the Mexico DPS (Wade et al. 2016). The proposed IHAs contained an 
estimate of 5 animals from the Mexico DPS.
    For Phase 2, NMFS has authorized a total of 16 total exposures of 
whales in the Level B harassment zone. This is based on the estimated 
occurrence rate of 2 groups of 2 individuals every 7 days and an 
anticipated timeframe of Phase 2 pile driving to occur over the course 
of 27 days (27 days/7 days per week x 2 groups x 2 animals/group = 15.4 
conservatively rounded up to 16). Based on the same estimated 
proportion of humpback whales in Southeast Alaska that belong to the 
ESA-listed Mexico DPS (Wade et al., 2016), there would be an estimated 
take by Level B harassment of one Mexico DPS humpback whale in Phase 2 
(16 x 0.061 = 0.97 rounded up to 1 whale). Therefore, the remaining 15 
whales taken by Level B harassment would be from the Hawaii DPS. In the 
proposed IHAs it was estimated that there would be 1 take from the 
Mexico DPS and a larger number of 16 from the Hawaii DPS due to a 
rounding error.
    Take by Level A harassment is not expected for humpback whales in 
Phase 1 or Phase 2 because of the expected effectiveness of the 
monitoring and mitigation measures and detecting and avoiding take by 
Level A harassment via shutdowns of pile installation equipment.
Minke Whales
    Minke whales may be present in Tongass Narrows and Clarence Strait 
year-round. Their abundance throughout Southeast Alaska is very low, 
and anecdotal reports have not included minke whales near the project 
area. However, minke whales are distributed throughout a wide variety 
of habitats and could occur near the project area. Minke whales are 
generally sighted as individuals (Dahlheim et al. 2009). Based on 
Freitag (2017 as cited in 83 FR 37473) it is estimated that three 
individual minke whales may occur in Tongass Narrows or Clarence Strait 
every 4 months.
    Based on the estimated occurrence rate of three individuals every 
four months, NMFS has authorized 7 takes of minke whale by Level B 
harassment (3 animals in a group x 1 group every 4 months = 7 
individuals in 9 months) during Phase 1. This represents a reduction 
from the 9 takes listed in the proposed IHAs since pile driving will 
occur over fewer months.
    Based on the estimated occurrence rate of three individuals every 4 
months, we have authorized 3 takes of minke whale by Level B harassment 
zone during the 3 month duration of Phase 2. This is a reduction from 
what was published in the proposed IHAs. Due to a mathematical error, 6 
minke whale takes were initially proposed to be authorized.
    Take by Level A harassment is not expected for minke whales in 
Phase 1 or Phase 2, because of the expected effectiveness of the 
monitoring and mitigation measures and detecting and avoiding take by 
Level A harassment via shutdowns of pile installation equipment. 
Additionally, minke whales are expected to be uncommon in the project 
area so they will likely not occur in the Level A harassment zone.

                                         Table 19--Take Estimates as a Percentage of Stock Abundance for Phase 1
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                               Total
                                                                             Estimated       Estimated       estimated                     Instances of
                                                                             number of       number of       exposures         Stock          take as
                  Species                             DPS/stock            exposures to    exposures to    (Level A and      abundance     percentage of
                                                                              Level B         Level A         Level B                       population
                                                                            harassment      harassment      harassment)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Steller sea lion..........................  Eastern DPS.................           2,025               0           2,025          41,638             4.9
Harbor seal...............................  Clarence Strait.............             861              18             879          31,634             2.8

[[Page 696]]

 
Harbor porpoise...........................  Southeast Alaska............             112              15             127          11,146             1.1
Dall's porpoise...........................  Alaska......................             327              15             342          83,400             0.4
Pacific white-sided dolphin...............  North Pacific...............              92               0              92          26,880             0.3
Killer whale..............................  AK Resident.................             144               0             144           2,347         \a\ 6.1
                                               Northern Resident........                                                             261        \a\ 55.2
                                               West Coast Transient.....                                                             243        \a\ 59.3
Humpback whale............................  Hawaii DPS..................             246               0             246          11,398         \b\ 2.2
                                            Mexico DPS..................              16               0              16           3,264         \b\ 0.5
Minke whale...............................  Alaska......................               7               0               7         Unknown             N/A
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note: DPS = distinct population segment.
\a\ These percentages assume all takes come from the same killer whale stock, thus the percentage should be adjusted down if multiple stocks are
  actually affected.
\b\ Assumes that 6.1 percent of humpback whales exposed are members of the Mexico DPS (Wade et al. 2016).


                                         Table 20--Take Estimates as a Percentage of Stock Abundance for Phase 2
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                               Total
                                                                             Estimated       Estimated       estimated                     Instances of
                                                                             number of       number of       exposures         Stock          take as
                  Species                             DPS/stock            exposures to    exposures to    (Level A and      abundance     percentage of
                                                                              Level B         Level A         Level B                       population
                                                                            harassment      harassment      harassment)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Steller sea lion..........................  Eastern DPS.................             450               0             450          41,638             1.1
Harbor seal...............................  Clarence Strait.............             162               9             171          31,634             0.5
Harbor porpoise...........................  Southeast Alaska............              30              10              40          11,146             0.4
Dall's porpoise...........................  Alaska......................              45              15              60          83,400            <0.1
Pacific white-sided dolphin...............  North Pacific...............              92               0              92          26,880             0.3
Killer whale..............................  Alaska resident.............  ..............  ..............  ..............           2,347         \a\ 2.5
                                               Northern Resident........              60               0              60             261        \a\ 22.9
                                               West Coast Transient.....  ..............  ..............  ..............             243        \a\ 24.6
Humpback whale............................  Hawaii DPS..................              15               0              15          11,398         \b\ 0.1
                                            Mexico DPS..................               1               0               1           3,264        \b\ <0.1
Minke whale...............................  Alaska......................               3               0               3         Unknown             N/A
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note: DPS = distinct population segment.
\a\ These percentages assume all takes come from the same killer whale stock, thus the percentage should be adjusted down if multiple stocks are
  actually impacted.
\b\ Assumes that 6.1 percent of humpback whales exposed are members of the Mexico DPS (Wade et al. 2016).

Mitigation

    In order to issue an IHA under Section 101(a)(5)(D) of the MMPA, 
NMFS must set forth the permissible methods of taking pursuant to the 
activity, and other means of effecting the least practicable impact on 
the species or stocks and their habitat, paying particular attention to 
rookeries, mating grounds, and areas of similar significance, and on 
the availability of the species or stocks for taking for 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 the activity and 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, we 
carefully consider two primary factors:
    (1) The manner in which, and the degree to which, the successful 
implementation of the measure(s) is expected to reduce impacts to 
marine mammals, marine mammal species or stocks, and their habitat. 
This considers the nature of the potential adverse impact being 
mitigated (likelihood, scope, range). It further considers the 
likelihood that the measure will be effective if implemented 
(probability of accomplishing the mitigating result if implemented as 
planned), the likelihood of effective implementation (probability 
implemented as planned), and;
    (2) the practicability of the measures for applicant 
implementation, which may consider such things as cost, impact on 
operations, and, in the case of a military readiness activity, 
personnel safety, practicality of implementation, and impact on the 
effectiveness of the military readiness activity.
    In addition to the measures described later in this section, 
ADOT&PF must employ the following standard mitigation measures:
     Conduct briefings between construction supervisors and 
crews and the marine mammal monitoring team prior to the start of all 
pile driving activity, and when new personnel join the work, to explain 
responsibilities, communication procedures, marine mammal monitoring 
protocol, and operational procedures;
     For in-water heavy machinery work other than pile driving/
removal and drilling (e.g., standard barges, tug boats), 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. This type of work could include the following 
activities: (1) Movement of the barge to the pile location; or (2) 
positioning of the pile on the substrate via a crane (i.e., stabbing 
the pile);
     Work may only occur during daylight hours, when visual 
monitoring of marine mammals can be conducted;
     For any marine mammal species for which take by Level B 
harassment has not been requested or authorized, in-

[[Page 697]]

water pile installation/removal and drilling will shut down immediately 
when the animals are sighted;
     In the event that more than one contractor is working at 
the same time, they will maintain radio or cellular coordination in 
order to coordinate pile installation and removal and provide adequate 
monitoring by protected species observers; and
     If take by Level B harassment reaches the authorized limit 
for an authorized species, pile installation will be stopped as these 
species approach the Level B harassment zone to avoid additional take 
of them.

The following specific mitigation measures will also apply to ADOT&PF's 
in-water construction activities:
    Establishment of Shutdown Zone for Level A Harassment--For all pile 
driving/removal and drilling activities, ADOT&PF will establish a 
shutdown zone. The purpose of a shutdown zone is generally to define an 
area within which shutdown of activity would occur upon sighting of a 
marine mammal (or in anticipation of an animal entering the defined 
area). Shutdown zones will vary based on the activity type, marine 
mammal hearing group, and in the case of impact pile driving, 
additional details about the activity including the expected number of 
pile strikes required, size of the pile, and number of piles to be 
driven during that day (See Table 21). Here, shutdown zones are 
generally larger than the calculated Level A harassment isopleths shown 
in Table 16 and Table 18. The largest shutdown zones are generally for 
low frequency and high frequency cetaceans as shown in Table 21. The 
placement of PSOs during all pile driving, pile removal, and drilling 
activities (described in detail in the Monitoring and Reporting 
Section) will ensure that the entire shutdown zone is visible during 
pile installation.
    The shutdown zones shown in Table 21 apply when a single piece of 
equipment is in use. In addition, ADOT&PF will implement a shutdown 
zone of 100 meters for each vibratory hammer on days when it is 
anticipated that multiple vibratory hammers will be used. The ADOT&PF 
will also implement a shutdown zone of 100 meters for each DTH drill on 
days when it is anticipated that two DTH drills will be used. Since 
conservative Level A harassment isopleths calculated for various 
concurrent driving combinations (Table 18) do not exceed 100 meters, 
there is no take by Level A harassment associated with simultaneous use 
of multiple devices.

                                           Table 21--Shutdown Zones During Use of a Single Piece of Equipment
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                            Piles                           Shutdown distances  (m)
                                                              Minutes per  pile or      installed or       Level B    ----------------------------------
             Activity                Pile size  (inches)        strikes per  pile       removed  per     harassment
                                                                                             day        isopleth  (m)    LF     MF     HF     PW     OW
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                    30...................  30 min....................               3           6,310                  50
Vibratory Installation............  24, 18...............  30 min....................               3           5,420
                                    27.6 sheet pile, 30.3  15 min....................              10           4,650
                                     sheet pile.
Vibratory Removal.................  24, 16...............  30 min....................               5           5,420
--------------------------------------------------------------------------------------------------------------------------------------------------------
Drilling Rock Sockets.............  30...................  180 min...................               3          12,030     70     50     60       50
                                                                                                                             --------------
                                    24, 18...............  120 min...................               3                     60       50
 
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                    30...................  50 strikes................               3           2,160    250     50    250    150     50
                                                                                                    2                    200           200    100
                                                                                                    1                    100           150    100
                                                           200 strikes...............               3                    550           650    300
                                                                                                    2                    400           500    250
                                                                                                    1                    300           300    150
Impact Installation...............  24...................  50 strikes................               3           1,000    150           150    100
                                                                                                    2                    100           150     50
                                                                                                    1                    100           100     50
                                                           200 strikes...............               3                    300           350    200
                                                                                                    2                    250           300    150
                                                                                                    1                    150           200    100
                                    18...................  50 strikes................               3                    150           150    100
                                                                                                    2                    100           150     50
                                                                                                    1                    100           100     50
--------------------------------------------------------------------------------------------------------------------------------------------------------

    Establishment of Monitoring Zones for Level B Harassment--ADOT&PF 
will establish monitoring zones, based on the Level B harassment zones 
which are areas where SPLs are equal to or exceed the 160 dB rms 
threshold for impact driving and the 120 dB rms threshold during 
vibratory driving, vibratory removal, and drilling. Monitoring zones 
provide utility for observing marine mammals by establishing monitoring 
protocols for areas adjacent to the shutdown zones. Monitoring zones 
enable observers to be aware of and communicate the presence of marine 
mammals in the project area outside the shutdown zone and thus prepare 
for a potential cease of activity should the animal enter the shutdown 
zone. The isopleths for the Level B harassment zones are depicted in 
Tables 13 and 14. On days and at times when a single piece of pile 
installation or removal equipment will be used, the Level B harassment 
zone as shown in Table 13 for each pile will be monitored and 
implemented according to pile size, type, and installation method as 
outlined. The largest Level B harassment zone for both Phase 1 and 
Phase 2 extends to a radius of 12,023 meters in at least one direction 
up or down Tongass Narrows when a single piece of driving equipment is 
being utilized, making it impracticable for the PSOs to consistently 
view the entire harassment area. Due to this, takes by Level B 
harassment will be recorded and extrapolated based upon the number of 
observed takes and the percentage of the Level B harassment zone that 
was not visible.

[[Page 698]]

    When two or more pieces of equipment are used simultaneously, and 
the noise they produce is not continuous or is a combination of 
continuous and impulsive, Table 21 will be followed to define the Level 
A harassment and Level B harassment monitoring zones for each piece of 
equipment.
    On days when multiple pieces of equipment that produce continuous 
noise are used simultaneously, source levels will be determined as 
shown in Table 9, Table 10, Table 11, and Table 12. The calculated 
source level will be used to determine the Level B harassment 
monitoring zones in accordance with values depicted in Table 14.
    Soft Start--The use of a soft-start procedure provides additional 
protection to marine mammals by providing warning and/or giving marine 
mammals a chance to leave the area prior to the hammer operating at 
full capacity. For impact pile driving, contractors will be required to 
provide an initial set of strikes from the hammer at reduced percent 
energy, each strike followed by no less than a 30-second waiting 
period. This procedure will be conducted a total of three times before 
impact pile driving begins. Soft Start is not required during vibratory 
pile driving and removal activities. If a marine mammal is present 
within the Level A harassment zone, soft start will be delayed until 
the animal leaves the Level A harassment zone. Soft start will begin 
only after the PSO has determined, through sighting, that the animal 
has moved outside the Level A harassment zone. If a marine mammal is 
present in the Level B harassment zone, soft start may begin and a take 
by Level B harassment will be recorded. Soft start up may occur when 
these species are in the Level B harassment zone, whether they enter 
the Level B harassment zone from the Level A harassment zone or from 
outside the project area.
    Pre-Activity Monitoring--Prior to the start of daily in-water 
construction activity, or whenever a break in pile driving of 30 
minutes or longer occurs, the PSO will observe the shutdown and 
monitoring zones for a period of 30 minutes. The shutdown zone will be 
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, a soft-start cannot proceed until the animal has left 
the zone or has not been observed for 15 minutes. If the Level B 
harassment zone has been observed for 30 minutes and marine mammals are 
not present within the zone, soft start procedures can commence and 
work can continue even if visibility becomes impaired within the Level 
B harassment zone. When a marine mammal permitted for take by Level B 
harassment is present in the Level B harassment zone, piling activities 
may begin and take by Level B harassment will be recorded. As stated 
above, if the entire Level B harassment zone is not visible at the 
start of construction, piling or drilling activities can begin. If work 
ceases for more than 30 minutes, the pre-activity monitoring of both 
the Level B harassment and shutdown zone will commence.
    Timing Restrictions--ADOT&PF plans to implement the Essential Fish 
Habitat (EFH) Conservation Recommendations developed by NMFS. These 
include a no in-water work timing window for three project components, 
Revilla New Ferry Berth and Upland Improvements, Gravina Airport Ferry 
Layup Facility, and Revilla Refurbish Existing Ferry Berth Facility, 
with no in-water work occurring between March 1 and June 15. 
Implementation of this timing window will likely reduce exposure/take 
of marine mammals to levels below what has been predicted, because some 
project locations will be able to install piles when other locations 
may not.
    During Phase 2 in-water pile installation and removal on the 
Revilla Island side of the Narrows will be limited to no more than 2 
hours that shall not coincide with in-water pile installation/removal 
activities on Gravina Island.
    Based on our evaluation of the applicant's required measures NMFS 
has determined that the mitigation measures provide the means of 
effecting the least practicable impact on the affected species or 
stocks and their habitat, paying particular attention to rookeries, 
mating grounds, and areas of similar significance.

Monitoring and Reporting

    In order to issue an IHA for an activity, Section 101(a)(5)(D) of 
the MMPA states that NMFS must set forth requirements pertaining to the 
monitoring and reporting of such taking. The MMPA implementing 
regulations at 50 CFR 216.104(a)(13) indicate that requests for 
authorizations must include the suggested means of accomplishing the 
necessary monitoring and reporting that will result in increased 
knowledge of the species and of the level of taking or impacts on 
populations of marine mammals that are expected to be present in the 
planned project 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).
     Mitigation and monitoring effectiveness.

Visual Monitoring

    Monitoring would be conducted 30 minutes before, during, and 30 
minutes after pile driving/removal and drilling activities. In 
addition, observers shall record all incidents of marine mammal 
occurrence, regardless of distance from activity, and shall document 
any behavioral reactions in concert with distance from piles being 
driven or removed. Pile driving activities include the time to install 
or remove a single pile or series of piles, as long as the time elapsed 
between uses of the pile driving equipment is no more than thirty 
minutes.
    There will be at least one PSO present at or near each construction 
site during in-water pile installation and removal so that all Level A 
harassment zones and shutdown zones are monitored by a dedicated PSO at 
all times. PSOs will not perform duties for more than 12 hours in a 24-
hour period. PSOs would be land-based observers, positioned at the best 
practical vantage points. At least one other PSO for each active 
worksite will begin at the central

[[Page 699]]

worksite and travel along the Tongass Narrows until they have reached 
the edges of the monitoring zones, based on the Level B harassment 
zones. These PSOs will then monitor the edges of the monitoring zone 
and as much as possible of the rest of the monitoring zone, looking for 
animals entering the Level B harassment zone. If waters exceed a sea 
state that restricts the PSO's ability to make observations within the 
Level A harassment zones (e.g., excessive wind or fog), pile 
installation and removal must cease. Pile driving must not be re-
initiated until the entire relevant Level A harassment zones are 
visible.
    When combinations of one DTH drill with a vibratory hammer, two DTH 
drills, or two DTH drills with a vibratory hammer are used 
simultaneously, creating a Level B harassment zone that is greater than 
12,023 meters in radius, one additional PSO (at least two total) will 
be stationed at the northernmost land-based location at the entrance to 
Tongass Narrows. One PSO will focus on Tongass Narrows, specifically 
watching for marine mammals that could approach or enter Tongass 
Narrows and the project area. The second PSO will look out into 
Clarence Strait, watching for marine mammals that could swim through 
the ensonified area. This monitoring requirement for concurrent driving 
scenarios was not included in the proposed IHAs. No additional PSOs 
will be required at the southern-most monitoring location because the 
Level B harassment zones are truncated to the southeast by islands, 
which prevent propagation of sound in that direction beyond the 
confines of Tongass Narrows. Takes by Level B harassment will be 
recorded by PSOs and extrapolated based upon the number of observed 
takes and the percentage of the Level B harassment zone that was not 
visible.
    With this configuration, PSOs can have a full view of the Level A 
harassment zone and awareness of as much of the Level B harassment zone 
as possible. This monitoring will provide information on marine mammal 
occurrence within Tongass Narrows and how these marine mammals are 
impacted by pile installation and removal.
    As part of monitoring, PSOs will scan the waters using binoculars, 
and/or spotting scopes, and will use a handheld GPS or range-finder 
device to verify the distance to each sighting from the project site. 
All PSOs will be trained in marine mammal identification and behaviors 
and are required to have no other project-related tasks while 
conducting monitoring. In addition, monitoring will be conducted by 
qualified observers, who will be placed at the best vantage point(s) 
practicable to monitor for marine mammals and implement shutdown/delay 
procedures when applicable by calling for the shutdown to the hammer 
operator. Each construction Contractor managing an active construction 
site and on-going in-water pile installation or removal will provide 
qualified, independent PSOs for their specific contract. The ADOT&PF 
environmental coordinator for the project will implement coordination 
between or among the PSO contractors. It will be a required component 
of their contracts that PSOs coordinate, collaborate, and otherwise 
work together to ensure compliance with project permits and 
authorizations. Qualified observers are trained and/or experienced 
professionals, with the following minimum qualifications:
     Visual acuity in both eyes (correction is permissible) 
sufficient for discernment of moving targets at the water's surface 
with ability to estimate target size and distance; use of binoculars 
may be necessary to correctly identify the target;
     Independent observers (i.e., not construction personnel);
     Observers must have their CVs/resumes submitted to and 
approved by NMFS;
     Advanced education in biological science or related field 
(i.e., undergraduate degree or higher). Observers may substitute 
experience or training for education;
     Experience and ability to conduct field observations and 
collect data according to assigned protocols (this may include academic 
experience);
     At least one observer must have prior experience working 
as an observer;
     Experience or training in the field identification of 
marine mammals, including the identification of behaviors;
     Sufficient training, orientation, or experience with the 
construction operation to provide for personal safety during 
observations;
     Writing skills sufficient to prepare a report of 
observations including but not limited to the number and species of 
marine mammals observed; dates and times when in-water construction 
activities were conducted; dates and times when in-water construction 
activities were suspended to avoid potential incidental injury from 
construction sound of marine mammals observed within a defined shutdown 
zone; and marine mammal behavior; and
     Ability to communicate orally, by radio or in person, with 
project personnel to provide real-time information on marine mammals 
observed in the area as necessary.

Reporting

    NMFS has issued two distinct and consecutive IHAs for these 
activities. In recognition of the value of marine mammal monitoring in 
understanding the impacts of ADOT&PF's activity, NMFS is requiring that 
ADOT&PF submit a preliminary marine mammal monitoring report for Phase 
1 of the project (2020 through 2021) at least 4 months prior to the 
effective date of the second IHA and initiation of Phase 2. This 
preliminary report must contain all items that would be included in the 
draft final report, listed below under ``Reporting''. This will allow 
NMFS to assess the impact of the activities relative to the analysis 
presented here, and modify the IHA for Phase 2 if the preliminary 
monitoring report shows unforeseen impacts on marine mammals in the 
area. If needed, NMFS will publish an amended proposed IHA, describing 
any changes but referencing the original IHA for Phase 2, and include 
an opportunity for the public to comment on the amended authorization.
    In addition to the preliminary monitoring report discussed above, 
separate draft marine mammal monitoring reports must be submitted to 
NMFS within 90 days after the completion of both Phase 1 and Phase 2 
pile driving, pile removal, and drilling activities. These reports will 
include an overall description of work completed, a narrative regarding 
marine mammal sightings, and associated PSO data sheets. Specifically, 
the reports must include:
     Date and time that monitored activity begins and ends;
     Construction activities occurring during each observation 
period;
     Weather parameters (e.g., percent cover, visibility);
     Water conditions (e.g., sea state, tide state);
     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 
pile driving activity;
     Distance from pile driving activities to marine mammals 
and distance from the marine mammals to the observation point;
     Locations of all marine mammal observations;
     An estimate of total take based on proportion of the 
monitoring zone that was observed; and

[[Page 700]]

     Other human activity in the area.
    If no comments are received from NMFS within 30 days, that phase's 
draft final report will constitute the final report. If comments are 
received, a final report for the given phase addressing NMFS comments 
must be submitted within 30 days after receipt of comments.
    In the event that personnel involved in the construction activities 
discover an injured or dead marine mammal, ADOT&PF shall report the 
incident to the Office of Protected Resources (OPR), NMFS and to the 
Alaska Regional Stranding Coordinator as soon as feasible. The report 
must include the following information:
     Time, date, and location (latitude/longitude) of the first 
discovery (and updated location information if known and applicable);
     Species identification (if known) or description of the 
animal(s) involved;
     Condition of the animal(s) (including carcass condition if 
the animal is dead);
     Observed behaviors of the animal(s), if alive;
     If available, photographs or video footage of the 
animal(s); and
     General circumstances under which the animal was 
discovered.

Negligible Impact Analyses and Determinations

    NMFS has defined negligible impact as an impact resulting from the 
specified activity that cannot be reasonably expected to, and is not 
reasonably likely to, adversely affect the species or stock through 
effects on annual rates of recruitment or survival (50 CFR 216.103). A 
negligible impact finding is based on the lack of likely adverse 
effects on annual rates of recruitment or survival (i.e., population-
level effects). An estimate of the number of takes alone is not enough 
information on which to base an impact determination. In addition to 
considering estimates of the number of marine mammals that might be 
``taken'' through harassment, NMFS considers other factors, such as the 
likely nature of any responses (e.g., intensity, duration), the context 
of any responses (e.g., critical reproductive time or location, 
migration), as well as effects on habitat, and the likely effectiveness 
of the mitigation. We also assess the number, intensity, and context of 
estimated takes by evaluating this information relative to population 
status. Consistent with the 1989 preamble for NMFS's implementing 
regulations (54 FR 40338; September 29, 1989), the impacts from other 
past and ongoing anthropogenic activities are incorporated into this 
analysis via their impacts on the environmental baseline (e.g., as 
reflected in the regulatory status of the species, population size and 
growth rate where known, ongoing sources of human-caused mortality, or 
ambient noise levels).
    To avoid repetition, our analysis applies to all species listed in 
Table 5 for which take could occur (i.e., not including gray whales and 
fin whales, for which take was found to be unlikely), given that NMFS 
expects the anticipated effects of the planned pile driving/removal and 
drilling to be similar in nature. Where there are meaningful 
differences between species or stocks, or groups of species, in 
anticipated individual responses to activities, impact of expected take 
on the population due to differences in population status, or impacts 
on habitat, NMFS has identified species-specific factors to inform the 
analysis. Additionally, the planned activity for both Phase 1 and Phase 
2 is similar in nature, so the impacts are expected to be similar and 
are analyzed as such, unless otherwise noted.
    NMFS does not anticipate that serious injury or mortality would 
occur as a result of ADOT&PF's planned activity. As stated in the 
mitigation section, shutdown zones that equal or exceed Level A 
harassment isopleths shown in Table 21 will be implemented. Take by 
Level A harassment is authorized for some species (harbor seals, harbor 
porpoises, and Dall's porpoises) to account for the slight possibility 
that these species escape observation by the PSOs within the shutdown 
zone. Further, any take by Level A harassment is expected to arise 
from, at most, a small degree of PTS because animals would need to be 
exposed to higher levels and/or longer duration than are expected to 
occur here in order to incur any more than a small degree of PTS. 
Additionally, and as noted previously, some subset of the individuals 
that are behaviorally harassed could also simultaneously incur some 
small degree of TTS for a short duration of time. Because of the small 
degree anticipated, though, any PTS or TTS potentially incurred here 
would not be expected to adversely impact individual fitness, let alone 
annual rates of recruitment or survival.
    Behavioral responses of marine mammals to pile driving, pile 
removal, and drilling at the sites in Tongass Narrows are expected to 
be mild, short term, and temporary. Marine mammals within the Level B 
harassment zone may not show any visual cues they are disturbed by 
activities or they could become alert, avoid the area, leave the area, 
or display other mild responses that are not observable such as changes 
in vocalization patterns. Given that pile driving, pile removal, and 
drilling would occur for only a portion of the project's two years and 
often on nonconsecutive days (101 days in Phase 1, or 27 days in Phase 
2), any harassment occurring during either phase would be temporary. 
Additionally, many of the species present in Tongass Narrows or 
Clarence Strait would only be present temporarily based on seasonal 
patterns or during transit between other habitats. These temporarily 
present species would be exposed to even smaller periods of noise-
generating activity, further decreasing the impacts.
    In addition, for all species except humpback whales, there are no 
known Biologically Important Areas (BIAs) near the project zone that 
would be impacted by ADOT&PF's planned activities. For humpback whales, 
the whole of Southeast Alaska is a seasonal BIA from spring through 
late fall (Ferguson et al., 2015), however, Tongass Narrows and 
Clarence Strait are not important portions of this habitat due to 
development and human presence. Tongass Narrows is also a small 
passageway and represents a very small portion of the total available 
habitat. There is no ESA-designated critical habitat for humpback 
whales.
    More generally, there are no known calving or rookery grounds 
within the project area, but anecdotal evidence from local experts 
shows that marine mammals are more prevalent in Tongass Narrows and 
Clarence Strait during spring and summer associated with feeding on 
aggregations of fish, meaning the area may play a role in foraging. 
Because ADOT&PF's activities, especially in Phase 1, could occur during 
any season, takes may occur during important feeding times. However, 
the project area represents a small portion of available foraging 
habitat and impacts on marine mammal feeding for all species, including 
humpback whales, should be minimal.
    Any impacts on marine mammal prey that would occur during ADOT&PF's 
planned activity would have at most short-term effects on foraging of 
individual marine mammals, and likely no effect on the populations of 
marine mammals as a whole. Indirect effects on marine mammal prey 
during the construction are expected to be minor, and these effects are 
unlikely to cause substantial effects on marine mammals at the 
individual level, with no expected effect on annual rates of 
recruitment or survival.

[[Page 701]]

    In summary and as described above, the following factors primarily 
support our determination that the impacts resulting from this 
activity, for both Phase 1 and Phase 2, are not expected to adversely 
affect the species or stocks through effects on annual rates of 
recruitment or survival:
     No serious injury or mortality is anticipated or 
authorized;
     ADOT&PF will implement mitigation measures including soft-
starts for impact pile driving and shutdown zones that exceed Level A 
harassment zones for most authorized species, which will help minimize 
the numbers of marine mammals exposed to injurious levels of sound, and 
to ensure that take by Level A harassment is at most a small degree of 
PTS;
     Level B harassment takes are not of a duration or 
intensity expected to result in impacts on reproduction or survival. 
Also, the only known area of specific biological importance covers a 
broad area of southeast Alaska for humpback whales, and the project 
area is a very small portion of that BIA. No other known areas of 
particular biological importance to any of the affected species or 
stocks are impacted by the activity; and
     The project area represents a very small portion of the 
available foraging area for all marine mammal species and anticipated 
habitat impacts are minor.
    Phase 1--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 required 
monitoring and mitigation measures, NMFS finds that the total marine 
mammal take from ADOT&PF's planned Phase 1 activities will have a 
negligible impact on all affected marine mammal species or stocks.
    Phase 2--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 required 
monitoring and mitigation measures, NMFS finds that the total marine 
mammal take from ADOT&PF's planned Phase 2 activities will have a 
negligible impact on all affected marine mammal species or stocks.

Small Numbers

    Only small numbers of incidental take may be authorized under 
Sections 101(a)(5)(A) and (D) of the MMPA for specified activities 
other than military readiness activities. The MMPA does not define 
small numbers and so, in practice, where estimated numbers are 
available, NMFS compares the number of individuals that may be 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. Additionally, other qualitative 
factors may be considered in the analysis, such as the temporal or 
spatial scale of the activities.
    Table 19 and Table 20, in the Marine Mammal Occurrence and Take 
Calculation and Estimation section, present the number of instances 
that animals could be exposed to received noise levels that may result 
in take by Level A harassment or Level B harassment for both Phase 1 
and Phase 2 of ADOT&PF's planned activities. The percentage of stock 
taken by harassment and is calculated by dividing the authorized number 
of takes by the best available stock population estimate. Our analysis 
of ADOT&PF's planned Phase 1 activity shows that for all but two of the 
three killer whale stocks mentioned above, less than seven percent of 
the best population estimates of each affected stock could be taken. 
Analysis of Phase 2 showed authorized takes represent less than 25 
percent of all stocks, which NMFS considers ``small numbers.'' There 
are two stocks, Northern Resident killer whales and West Coast 
Transient killer whales, for which the estimated percentage of stock 
taken in Phase 1 appears high when compared to other stocks and species 
(Table 19). However, when other qualitative factors are used to inform 
an assessment of the likely number of individual marine mammals taken, 
the resulting numbers are appropriately considered small. Initial 
analysis (which assumes that all takes could accrue to any of the three 
stocks, and is very unlikely) of the West Coast Transient stock shows 
that in Phase 1, when instances of take (not individuals taken) are 
compared to the stock abundance, 59.3 percent of the stock could 
experience take. For the Northern Resident stock, the initial analysis 
shows that when instances of take (not individuals taken) are compared 
to the stock abundance, 55.2 percent of the stock could experience 
take. While these numbers appear high, the extensive ranges of both 
stocks compared to ADOT&PF's project area mean that realistically there 
will be multiple takes of a smaller number of individuals from these 
stocks, resulting in no more than a third of the individuals of any of 
these stocks being taken. The Northern Resident stock's range stretches 
from Washington State into southeast Alaska and the stock is frequently 
observed along British Columbia, Canada (Muto et al. 2018). The West 
Coast transient stock occurs in California, Oregon, Washington, British 
Columbia, and southeastern Alaska. In both cases, ADOT&PF is only 
impacting a small portion of the total range, and this impact is 
intermittent.
    Further, the above percentages are based on analyzing the entire 
estimated take of killer whales as if it would occur to a single killer 
whale stock, which is extremely unlikely to occur, instead of 
apportioned among the three stocks that could occur in the area. 
Realistically, the take will be spread in some way among the stocks 
expected to be in the area (i.e., 100 percent of the take cannot occur 
to each of the three stocks), further reducing the percentage of takes 
anticipated to come from any single stock. For example, if we assumed 
that the take were equally apportioned across the three stocks, the 
predicted percentages are both reduced to below one third of the 
population. When this is considered in combination with large ranges of 
the two stocks noted above, it is entirely unlikely that more than one 
third of the Northern Resident or West Coast Transient killer whale 
stocks would be taken in Phase 1 of the project.
    For both Phase 1 and Phase 2, there was one stock, minke whale, 
where the lack of an accepted stock abundance value prevented us from 
calculating an expected percentage of the population that would be 
affected. The most relevant estimate of partial stock abundance is 
1,233 minke whales for a portion of the Gulf of Alaska (Zerbini et al., 
2006). Given the estimated 7 authorized takes by Level B harassment for 
the stock in Phase 1, comparison to the best estimate of stock 
abundance shows less than 1 percent of the stock is expected to be 
impacted. A similar analysis of Phase 2, with 3 takes of minke whale by 
Level B harassment authorized, in comparison to the best estimate of 
stock abundance shows less than 1 percent of the stock is expected to 
be impacted. Additionally, the range of the Alaska stock of minke 
whales is extensive, stretching from the Canadian Pacific coast to the 
Chukchi Sea, and ADOT&PF's project area impacts a small portion of this 
range. Therefore, the numbers of minke whales authorized to be taken 
are small relative to estimated survey abundance even if each estimated 
taking occurred to a new individual.
    Phase 1--Based on the analysis contained herein of the planned 
activity (including the required mitigation and monitoring measures) 
and the anticipated take of marine mammals for

[[Page 702]]

Phase 1 of ADOT&PF's activity, NMFS finds that small numbers of marine 
mammals will be taken relative to the population size of the affected 
species or stocks in Phase 1 of the project.
    Phase 2--Based on the analysis contained herein of the planned 
activity (including the mitigation and monitoring measures) and the 
anticipated take of marine mammals for Phase 2 of ADOT&PF's activity, 
NMFS finds that small numbers of marine mammals will be taken relative 
to the population size of the affected species or stocks in Phase 2 of 
the project.

Unmitigable Adverse Impact Analysis and Determination

    In order to issue an IHA, NMFS must find that the specified 
activity will not have an ``unmitigable adverse impact'' on the 
subsistence uses of the affected marine mammal species or stocks by 
Alaskan Natives. NMFS has defined ``unmitigable adverse impact'' in 50 
CFR 216.103 as an impact resulting from the specified activity: (1) 
That is likely to reduce the availability of the species to a level 
insufficient for a harvest to meet subsistence needs by: (i) Causing 
the marine mammals to abandon or avoid hunting areas; (ii) Directly 
displacing subsistence users; or (iii) Placing physical barriers 
between the marine mammals and the subsistence hunters; and (2) That 
cannot be sufficiently mitigated by other measures to increase the 
availability of marine mammals to allow subsistence needs to be met.
    Harbor seals are the marine mammal species most regularly harvested 
for subsistence by households in Ketchikan and Saxman (A community a 
few miles south of Ketchikan, on the Tongass Narrows). Eighty harbor 
seals were harvested by Ketchikan residents in 2007, which ranked 
fourth among all communities in Alaska that year for harvest of harbor 
seals. Thirteen harbor seals were harvested by Saxman residents in 
2007. In 2008, two Steller sea lions were harvested by Ketchikan-based 
subsistence hunters, but this is the only record of sea lion harvest by 
residents of either Ketchikan or Saxman. In 2012, the community of 
Ketchikan had an estimated subsistence take of 22 harbor seals and 0 
Steller sea lion (Wolf et al., 2013). This is the most recent data 
available. Hunting usually occurs in October and November (ADF&G 2009), 
but there are also records of relatively high harvest in May (Wolfe et 
al., 2013). The Alaska Department of Fish and Game (ADF&G) has not 
recorded harvest of cetaceans from either community (ADF&G 2018). All 
project activities will take place within the industrial area of 
Tongass Narrows immediately adjacent to Ketchikan where subsistence 
activities do not generally occur. The project also will not have an 
adverse impact on the availability of marine mammals for subsistence 
use at locations farther away, where these construction activities are 
not expected to take place. Some minor, short-term harassment of the 
harbor seals could occur, but any effects on subsistence harvest 
activities in the region will be minimal, and not have an adverse 
impact.
    Phase 1--Based on the effects and location of the specified 
activity, and the mitigation and monitoring measures, NMFS has 
determined that there will not be an unmitigable adverse impact on 
subsistence uses from Phase 1 of ADOT&PF's planned activities.
    Phase 2--Based on the effects and location of the specified 
activity, and the mitigation and monitoring measures, NMFS has 
determined that there will not be an unmitigable adverse impact on 
subsistence uses from Phase 2 of ADOT&PF's planned activities.

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 action (i.e., the issuance of incidental 
harassment authorizations) with respect to potential impacts on the 
human environment.
    This action is consistent with categories of activities identified 
in Categorical Exclusion B4 (incidental harassment authorizations with 
no anticipated serious injury or mortality) of the Companion Manual for 
NOAA Administrative Order 216-6A, which do not individually or 
cumulatively have the potential for significant impacts on the quality 
of the human environment and for which we have not identified any 
extraordinary circumstances that would preclude this categorical 
exclusion. Accordingly, NMFS has determined that the issuance of the 
IHAs qualify to be categorically excluded from further NEPA review.

Endangered Species Act (ESA)

    Section 7(a)(2) of the Endangered Species Act of 1973 (ESA: 16 
U.S.C. 1531 et seq.) requires that each Federal agency insure that any 
action it authorizes, funds, or carries out is not likely to jeopardize 
the continued existence of any endangered or threatened species or 
result in the destruction or adverse modification of designated 
critical habitat. To ensure ESA compliance for the issuance of IHAs, 
NMFS' Office of Protected Resources consults internally, in this case 
with NMFS' Alaska Regional Office, whenever we propose to authorize 
take for endangered or threatened species.
    NMFS is authorizing take of the Central North Pacific stock of 
humpback whales, of which a portion belong to the Mexico DPS of 
humpback whales, which are listed under the ESA.
    The action agency are the Federal Highway Administration (FHA) and 
the NMFS Office of Protected Resources Permits and Conservation 
Division. On February 6, 2019, NMFS completed consultation with ADOT&PF 
for Tongass Narrows Project and issued a Biological Opinion with the 
FHA as an action agency. Reinitiation of formal consultation was 
required to add NMFS Permits and Conservation Division as an action 
agency and to analyze changes to the action that were not considered in 
the February 2019 opinion (PCTS# AKR-2018-9806/ECO# AKRO-2018-01287). 
The original opinion considered the effects of only one project 
component being constructed at a time and did not analyze potential 
effects of concurrent pile driving which may cause effects to the 
listed species that were not considered in the original opinion; 
therefore, reinitiation of formal consultation was required.
    NMFS' Alaska Region issued a revised Biological Opinion to NMFS' 
Office of Protected Resources on December 19, 2019 which concluded that 
issuance of IHAs to ADOT&PF is not likely to jeopardize the continued 
existence of Mexico DPS humpback whales.

Authorizations

    NMFS has issued two separate, consecutive IHAs to ADOT&PF for 
incidental take resulting from pile ferry berth improvements and 
construction activities in Tongass Narrows, Alaska in 2020 through 2021 
(Phase 1) and 2021 through 2022 (Phase 2), including the previously 
discussed mitigation, monitoring, and reporting requirements that have 
been incorporated.

    Dated: December 20, 2019.
Donna S. Wieting,
Director, Office of Protected Resources, National Marine Fisheries 
Service.
[FR Doc. 2020-00038 Filed 1-6-20; 8:45 am]
 BILLING CODE 3510-22-P