[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
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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.
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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
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* (+13 Removal)
Table 4--Number of Temporary Piles To Be Installed and Removed for Each Project Component and Structure During Phase 2
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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)
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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.
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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