[Federal Register Volume 85, Number 154 (Monday, August 10, 2020)]
[Notices]
[Pages 48153-48179]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2020-17344]
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DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
[RTID 0648-XA122]
Take of Marine Mammals Incidental to Specified Activities; Taking
Marine Mammals Incidental to the Hampton Roads Bridge-Tunnel Expansion
Project, Hampton-Norfolk, Virginia
AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and
Atmospheric Administration (NOAA), Commerce.
ACTION: Notice; issuance of an incidental harassment authorization.
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SUMMARY: In accordance with the regulations implementing the Marine
Mammal Protection Act (MMPA) as amended, notification is hereby given
that NMFS has issued an incidental harassment authorization (IHA) to
the Hampton Roads Connector Partners (HRCP) to incidentally harass, by
Level A and Level B harassment, marine mammals during pile driving and
removal activities associated with the Hampton Roads Bridge-Tunnel
(HRBT) Expansion Project, Hampton-Norfolk, Virginia.
DATES: This Authorization is effective for one year from July 10, 2020
to July 9, 2021.
FOR FURTHER INFORMATION CONTACT: Stephanie Egger, 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 may be provided to the public
for review. Under the MMPA, ``take'' is defined as meaning to harass,
hunt, capture, or kill, or attempt to harass, hunt, capture, or kill
any marine mammal.
Authorization for incidental takings shall be granted if NMFS finds
that the taking will have a negligible impact on the species or
stock(s) and will not have an unmitigable adverse impact on the
availability of the species or stock(s) for taking for subsistence uses
(where relevant). Further, NMFS must prescribe the permissible methods
of taking and other ``means of effecting the least practicable adverse
impact'' on the affected species or stocks and their habitat, paying
particular attention to rookeries, mating grounds, and areas of similar
significance, and on the availability of such species or stocks for
taking for certain subsistence uses (referred to in shorthand as
``mitigation''); and requirements pertaining to the mitigation,
monitoring and reporting of such takings are set forth. The definitions
of all applicable MMPA statutory terms cited above are included in the
relevant sections below.
Summary of Request
On September 18, 2019, NMFS received a request from the HRCP for an
IHA to take marine mammals incidental to impact and vibratory pile
driving activities associated with the HRBT, in Hampton and Norfolk,
Virginia for one year from the date of issuance. The application was
deemed adequate and complete on February 4, 2020. The HRCP request is
for take of a small number of five species of marine mammals by Level A
and B harassment. Neither the HRCP nor NMFS expects injury, serious
injury or mortality to result from this activity and, therefore, an IHA
is appropriate. The planned activities are part of a larger project and
the applicant has requested rulemaking and a letter of authorization
for the other components of this project.
Description of Specified Activity
Overview
The HRCP is working with the Virginia Department of Transportation
(VDOT) and Federal and state agencies to advance the design, approvals,
and multi-year construction of the Interstate (I)-64 HRBT Expansion
project. The overall project will widen I-64 for approximately 15.93
kilometer (km) (9.9 miles) along I-64 from Settlers Landing Road in
Hampton, Virginia to the I-64/I-564 interchange in Norfolk, Virginia.
The project will create an eight-lane facility with six consistent use
lanes. The project will include full replacement of the North and South
Trestle Bridges, two new parallel tunnels constructed using a Tunnel
Boring Machine (TBM), expansion of the existing portal islands, and
widening of the Willoughby Bay Trestle Bridges, Bay Avenue Trestle
Bridges, and Oastes Creek Trestle Bridges. Also, upland portions of I-
64 will be widened to accommodate the additional lanes, the Mallory
Street Bridge will be replaced, and the I-64 overpass bridges will be
improved. The planned activities below are part of the overall project
(see the application for additional details on the overall project).
Only the activities relevant to the IHA requested by HRCP are discussed
below. This includes the following components:
[ssquf] TBM Platform at the South Island;
[ssquf] Conveyor Trestle at the South Island;
[ssquf] Temporary trestles for jet grouting at the South Island;
[ssquf] Temporary trestle for bridge construction at the North
Shore;
[ssquf] Mooring piles at the South Trestle (located at the South
Island), North Island, and Willoughby Bay; and
[ssquf] Installation and removal of piles for test pile program.
Pile installation methods will include impact and vibratory
driving, jetting, and drilling with a down-the-hole (DTH) hammer. Pile
removal techniques for temporary piles will include vibratory pile
removal or cutting below the mud line. Installation of steel pipe piles
could be 24-, 36-, or 42-inches (in) in diameter to support temporary
work trestles, platforms, and moorings. Test piles would consist of 30-
in square concrete or 54-in concrete cylinder piles. Only load test
piles will be removed under this IHA. In-water pile installation using
impact and vibratory driving, and drilling with a DTH hammer, and pile
removal using a vibratory hammer, have the potential to harass marine
mammals acoustically and could result in incidental takes of individual
marine mammals. Jetting is not likely to result in take.
Dates and Duration
Work could occur at any point during the year, and will occur
during the day. Pile installation may extend into
[[Page 48154]]
evening or nighttime hours as needed to accommodate pile installation
requirements (e.g., once pile driving begins--a pile will be driven to
design tip elevation). The overall number of anticipated days of pile
installation is 312, based on a 6-day work week for one year. Pile
installation can occur at variable rates, from a few minutes to several
hours per pile. The HRCP anticipate that 1 to 10 piles could be
installed per day. In order to account for inefficiencies and delays,
the HRCP have estimated an average installation rate of six piles per
day for most components.
Specific Geographic Region
The HRBT is located in the waterway of Hampton Roads adjacent to
the existing bridge and island structures of the HRBT in Virginia.
Hampton Roads is located at the confluence of the James River, the
Elizabeth River, the Nansemond River, Willoughby Bay, and the
Chesapeake Bay (Figure 1). Hampton Roads is a wide marine channel that
provides access to the Port of Virginia and several other deep water
anchorages upstream of the project area (VDOT and Federal Highway
Administration (FHWA) 2016). Navigational channels are maintained by
the U. S. Army Corps of Engineers within Hampton Roads to provide
transit to the many ports in the region.
[GRAPHIC] [TIFF OMITTED] TN10AU20.000
Pile installation will occur in waters ranging in depth from less
than 1 meter (m) (3.3 feet (ft)) near the shore to approximately 8 m
(28 ft), depending on the structure and location. The majority of the
piles will be in water depths of 3.6-4.6 m (12-15 ft).
Detailed Description of the Specific Activity
Three methods of pile installation are anticipated and expected to
result in take of marine mammals. These include use of vibratory,
impact, and DTH hammers. More than one installation method will be used
within a day. Most piles will be installed using a combination of
vibratory (ICE 416L or similar) and impact hammers (S35 or similar).
Overall, steel pipe piles at the North Shore Work Trestle, Jet Grouting
Trestle, and TBM Platform would be installed using the vibratory hammer
approximately 80 percent of the time and impact hammer approximately 20
percent of the time, while all mooring piles and steel pipe piles at
Conveyor Trestle would be installed using the
[[Page 48155]]
vibratory hammer approximately 90 percent and the impact hammer
approximately 10 percent of the time. Depending on the location, the
pile will be advanced using vibratory methods and then impact driven to
final tip elevation. Where bearing layer sediments are deep, driving
will be conducted using an impact hammer so that the structural
capacity of the pile embedment can be verified. The pile installation
methods used will depend on sediment depth and conditions at each pile
location. Table 1 provides additional information on the pile driving
operation including estimated pile driving times. The sum of the days
of pile installation is greater than the anticipated number of days
because more than one pile installation method will be used within a
day.
Prior to installing steel pipe piles near shorelines protected with
rock armor and/or rip rap (e.g., South Island shorelines; North Shore
shoreline), it will be necessary to temporarily shift the rock armoring
that protects the shoreline to an adjacent area to allow for the
installation of the piles. The rock armor should only be encountered at
the shoreline and at relatively shallow depths below the mudline. The
rock armor and/or rip rap will be moved and reinstalled near its
original location following the completion of pile installation.
Alternatively, the piles may be installed without moving the rock, by
first drilling through the rock with a DTH hammer (e.g., Berminghammer
BH 80 drill or equivalent) to allow for the installation of the piles.
It is estimated that a down-the-hole hammer will be used for
approximately 1 to 2 hours per pile, when necessary. It is anticipated
that approximately 5 percent of the North Shore Work Trestle piles, 10
percent of the Jet Grouting Trestle piles, 10 percent of the Conveyor
Trestle piles, and 50 percent of the TBM Platform piles may require use
of a down-the-hole hammer (Table 1).
Detailed descriptions of the project components for this IHA
request are explained below.
Project Segments
The project design is divided into five segments (see also Figure
2) as follows:
Segment 1a (Hampton) begins at the northern terminus of
the Project in Hampton and ends at the north end of the north approach
slabs for the north tunnel approach trestles. This segment has two
interchanges and also includes improvements along Mallory Street to
accommodate the bridge replacement over I-64. This segment covers
approximately 1.2 miles along I-64;
Segment 1b (North Trestle-Bridges) includes the new and
replacement north tunnel approach trestles, including any approach
slabs. This segment covers approximately 1 km (0.6 mi) along I-64;
Segment 2a (Tunnel) includes the new bored tunnels, the
tunnel approach structures, buildings, the North Island improvements
for tunnel facilities, and South Island improvements. This segment
covers approximately 2.9 km (1.8 mi) along I-64;
Segment 3a (South Trestle-Bridge) includes the new South
Trestle-Bridge and any bridge elements that interface with the South
Island to the south end of the south abutments at Willoughby Spit. This
segment covers approximately 1.93 km (1.2 mi) along I-64;
Segment 3b (Willoughby Spit) continues from the south end
of the south approach slabs for the south trestle and ends at the north
end of the north approach slabs for the Willoughby Bay trestles. This
segment includes a modified interchange connection to Bayville Street,
and has a truck inspection station for the westbound tunnels. This
segment covers approximately 1 km (0.6 mi) along I-64;
Segment 3c (Willoughby Bay Trestle-Bridges) includes the
entire structures over Willoughby Bay, from the north end of the north
approach slabs on Willoughby Spit to the south end of south approach
slabs near the 4th View Street interchange. This segment covers
approximately 1.6 km (1.0 mi) along I-64;
Segment 3d (4th View Street Interchange) continues from
the Willoughby Trestle-Bridges south, leading to the north end of the
north approach slabs of I-64 bridges over Mason Creek Road along
mainline I-64. This segment covers approximately 1.6 km (1.0 mi) along
I-64;
Segment 4a (Norfolk-Navy) goes from the I-64 north end of
the north approach slabs at Mason Creek Road to the north end of the
north approach slabs at New Gate/Patrol Road. There are three
interchange ramps in this segment: Westbound I-64 exit ramp to Bay
Avenue, eastbound I-64 entrance ramp from Ocean Avenue, and westbound
I-64 entrance ramp from Granby Street. The ramps in this segment are
all on structure. This segment covers approximately 2.4 km (1.5 mi)
along I-64; and
Segment 5a (I-564 Interchange) starts from the north end
of the north approach slab of the New Gate/Patrol Road Bridge to the
southern Project Limit. This segment runs along the Navy property and
includes an entrance ramp from Patrol Road, access ramps to and from
the existing I-64 Express Lanes, ramps to and from I-564, and an
eastbound I-64 entrance ramp from Little Creek Road. This segment
covers approximately 1.93 km (1.2 mi) along I-64.
[[Page 48156]]
[GRAPHIC] [TIFF OMITTED] TN10AU20.001
However, the only planned in-water marine construction activities
that have potential to affect marine mammals and result in take would
occur at the following locations in the following segments:
[ssquf] North Trestle-Bridges (Segment 1b);
[ssquf] Tunnel--North Island and South Island (Segment 2a);
[ssquf] South Trestle-Bridge (Segment 3a); and
[ssquf] Willoughby Bay Trestle-Bridges (Segment 3c).
Approximately, 1070 piles (of all sizes) would be installed (only
some removed) under this IHA (Table 1). For 36-in steel piles, 698
piles would be installed. For 42-in steel piles, 257 piles would be
installed. For 24-in piles, 66 piles would be installed. For 54-in
concrete cylinder piles, 33 piles would be installed. For 24-in or 30-
in concrete square piles, 16 piles would be installed. Removal would
only occur for piles as part of the test pile program (Table 1).
Project Components That Are Likely To Result in Take of Marine Mammals
Tunnel Boring Machine (TBM) Platform at the South Island (Segment
2a)--The HRCP is constructing the temporary TBM Platform or ``quay'' at
the South Island to allow for the delivery, unloading, and assembly of
the TBM components from barges to the Island. The large TBM components
will be delivered by barge and then transferred to the platform using a
Self-
[[Page 48157]]
Propelled Modular Transport, crawler crane, sheerleg crane and/or other
suitable equipment. The TBM Platform will also allow barge delivery and
storage of concrete tunnel segments as the boring operation progresses.
The concrete tunnel segments will be offloaded and moved using a
combination of crawler cranes and a gantry crane installed on the TBM
Platform. The tunnel segments will be stored on the platform prior to
delivery to the tunnel shaft for installation.
The TBM Platform is a steel structure founded on (216) 36-in
diameter steel piles, with an overall area of approximately 0.40 acres
(approximately 50.6 m x 2.7 m). The piles will be installed using a
combination of vibratory and impact hammers except along the perimeter
where down-the-hole hammering may be needed to install piles through
the rock armor stone. The piles are 47 m (154 ft) long and will have an
average embedded length of approximately 42.7 m (140 ft). Table 1
provides additional information on the pile driving operation including
estimated pile installation times and number of strikes necessary to
drive a pile to completion.
The superstructure of the platform is set on top of the piles and
consists of transverse and longitudinal beams below a 13/16-in-thick
plate set on top of the beams. Rail beams will be installed on top of
the plate and will support the gantry crane. A concrete slab may be
placed on top of the steel plates or timber trusses.
Dolphins will be installed along the shoreline of the South Island
in the areas adjacent to the TBM Platform. Each dolphin will consist of
36-in steel piles and will be installed with a combination of vibratory
and impact hammers.
Conveyor Trestle at the South Island (Segment 2a)--Tunnel boring
spoils and other related materials will be moved between the South
Island and barges via a conveyor belt and other equipment throughout
tunnel boring. The Conveyor Trestle will also be used for maintenance
and mooring of barges and vessels carrying TBM materials and other
project related materials.
The Conveyor Trestle is a steel structure founded on (84) 36-in
diameter steel piles, with an overall area of approximately 0.42 acres
(approximately 205 m x 8 m). The piles will be installed using a
combination of vibratory (International Construction Equipment (ICE)
416L or similar) and impact hammers (S35 or similar). The piles are
approximately 42.7 m (140 ft) long and will have an average embedded
length of approximately 30.5 m (100 ft). Table 1 provides additional
information on the pile driving operation including estimated pile
driving times and number of strikes necessary to drive a pile to
completion.
Additionally, mooring dolphins will be installed along the outside
edge of the Conveyor Trestle. Each dolphin will consist of 36-in steel
piles and will be installed with a combination of vibratory and impact
hammers.
Temporary Trestle for Bridge Construction at the North Shore Work
Trestle (Segment 1b)--The temporary North Shore Work Trestle will
support construction of the permanent eastbound North Trestle Bridge in
the shallow water (<1.2-1.8 m (4-6 ft) MLW) closer to the North Shore,
avoiding the need to dredge or deepen this area (which otherwise would
have been required for barge access) and minimizing potential impacts
to the adjacent submerged aquatic vegetation (SAV). The temporary North
Shore Work Trestle is a steel structure founded on 194 36-in diameter
steel piles with 9-12 m (30-40 ft) spans sized to accommodate a 300-ton
crane. The main portion of the work trestle will be approximately 345 m
long x 14 m wide (1,130 ft long by 45 ft wide), with three
approximately 24.4 m x 9 m (80 ft x 30 ft) fingers and an additional
landing area approximately 45.7 m x 14 m (150 ft x 45 ft), for a total
overall approximate area of 0.006 km\2\ (1.49 acres).
Dolphins will be installed at the southern end and along the
outside edge of the work trestle. Each dolphin will consist of 24-in
steel piles. In addition, 42-in steel pipe piles will be installed
along the outer edge of the work trestle to provide additional single
mooring points for barges and vessels delivering material and accessing
the trestle. The mooring dolphin piles and the single mooring point
piles will be installed using a vibratory hammer.
Moorings at the North Island Expansion (Segment 2a)--Temporary
moorings will be installed along the perimeter of the North Island
Expansion area to support the construction of the Island expansion.
Eighty 42-in steel pipe piles will be installed to provide mooring
points for barges and vessels. The mooring point piles will be
installed using a vibratory hammer.
Temporary Trestles for Jet Grouting at the South Island (Segment
2a)--Unconsolidated soil conditions at the western edge of the South
Island--along the centerline and depth of the planned tunnel
alignment--require ground improvements to allow tunnel boring to
proceed safely and efficiently. Ground improvements will be achieved
using deep injection or jet grouting to stabilize and consolidate the
sediments along the planned tunnel alignment and tunnel depth.
Two temporary work trestles will be constructed along either side
of the planned tunnel alignment to support jet grouting activity. Each
trestle will be approximately 12.2 m (40 ft) wide and extend
approximately 305 m (1,000 ft) west of the South Island shoreline, for
a total overall approximate area of 0.007 km\2\ (1.84 acres). Two
temporary Jet Grouting Trestles will be constructed, each will be
founded on (102) 36-in diameter steel piles (a total of 204 steel
piles) with 7.6 m (25 ft) +/- spans sized to accommodate a 35-ton drill
rig and support equipment.
Moorings at the South Trestle (Segment 3a)--Temporary moorings will
be installed in the area of the South Trestle to support the
construction of temporary work trestles and permanent trestle bridges.
Six mooring dolphins will be installed and each will consist of (3) 24-
in steel piles for a total of (18) 24-in piles. An additional (41) 42-
in steel pipe piles will be installed along what will become the outer
edge of the work trestle to provide additional single mooring points
for barges and vessels delivering material and accessing the trestle.
The mooring dolphin piles and the single mooring point piles will be
installed using a vibratory hammer.
Mooring at Willoughby Bay (Segment 3c)--Temporary moorings will be
installed in Willoughby Bay to support the construction of temporary
work trestles and permanent trestle bridges. Six mooring dolphins will
be installed--each consisting of (3) 24-in steel piles. An additional
(50) 42-in steel pipe piles will be installed along what will become
the outer edge of the work trestle to provide additional single mooring
points for barges and vessels delivering material and accessing the
trestle. The mooring dolphin piles and the single mooring point piles
will be installed using a vibratory hammer. A total of 68 steel pipe
piles will be driven, (50) 42-in piles and (18) 24-in piles.
An additional (50) 42-in steel pipe piles will be installed in
Willoughby Bay to create moorings for additional staging of barges and
safe haven for vessels in the event of severe weather. The moorings
will be configured as (2) 2,000-ft long lines with a 42-in mooring pile
every 24.4 m (80 ft). The piles will be installed using a vibratory
hammer.
Installation and Removal of Piles for Test Pile Program (Segments 1b,
2a, 3a, and 3c)
The HRCP will perform limited pile load testing to confirm
permanent
[[Page 48158]]
concrete pile design at the start of the project. Test piles will be
installed at the North Trestle (1 load test pile, 10 production test
piles), South Trestle (2 load test piles, 20 production test piles) and
at Willoughby Bay (1 load test pile, 15 production test piles)--test
piles will be 30-in square concrete or 54-in concrete cylinder piles
(see Table 1). Test piles will be set using temporary steel templates
designed to support and position the test pile while being driven.
Concrete test piles will be driven using an impact hammer. Test pile
templates will be positioned and held in place using spuds (one at each
corner of the template). The test pile templates and pile load test
frame and supports will be installed using a vibratory hammer and
proofed using an impact hammer to confirm sufficient load capacity.
Test piles will be cut below the mudline and removed. The temporary
test pile templates and load test frame and supports will be removed
using a vibratory hammer.
Table 1--Pile Driving and Removal Associated With the HRBT Project That Are Likely To Result in the Take of Marine Mammals
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Average
down-the- Number of Average Approximate Number of Estimated
Pile size)/ type and Total Embedment Number of hole piles vibratory number of piles per total number Number of
Project component material number of length piles down- duration vibrated/ duration impact day per of hours of days of
piles (feet) the-hole per pile hammered per pile strikes per hammer installation installation
(minutes) (minutes) pile
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North Trestle (Segment 1b)
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North Shore Work Trestle............ 36-in Steel Pipe...... 194 100 10 120 184 50 40 3 162 65
Moorings............................ 42-in Steel Pipe...... 36 60 ........... ........... 36 30 ........... 6 18 6
Moorings............................ 24-in Steel Pipe...... 30 60 ........... ........... 30 30 ........... 6 15 5
Test Pile Program (Load Test Piles). 54-in Concrete 1 140 ........... ........... 1 ........... 2,100 1 2 1
Cylinder Pipe.
Test Pile Program (Production Piles) 54-in Concrete 10 140 ........... ........... 10 ........... 2,100 1 20 10
Cylinder Pipe.
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North Island (Segment 2a)
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Moorings............................ 42-in Steel Pipe...... 80 60 ........... ........... 80 30 ........... 6 40 13
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Willoughby Bay (Segment 3c)
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Moorings............................ 42-in Steel Pipe...... 50 60 ........... ........... 50 30 ........... 6 25 9
Moorings............................ 24-in Steel Pipe...... 18 60 ........... ........... 18 30 ........... 6 9 3
Moorings (Safe Haven)............... 42-in Steel Pipe...... 50 60 ........... ........... 50 30 ........... 6 25 9
Test Pile Program (Load Test Piles). 24-in or 30-in 1 140 ........... ........... 1 ........... 2,100 1 2 1
Concrete Square Pipe.
Test Pile Program (Production Piles) 24-in or 30-in 15 140 ........... ........... 15 ........... 2,100 1 30 15
Concrete Square Pipe.
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South Trestle (Segment 3a)
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Moorings............................ 42-in Steel Pipe...... 41 60 ........... ........... 41 30 ........... 6 21 7
Moorings............................ 24-in Steel Pipe...... 18 60 ........... ........... 18 30 ........... 6 9 3
Test Pile Program (Load Test Piles). 54-in Concrete 2 140 ........... ........... 2 ........... 2,100 1 4 2
Cylinder Pipe.
Test Pile Program (Production Piles) 54-in Concrete 20 140 ........... ........... 20 ........... 2,100 1 40 20
Cylinder Pipe.
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South Island (Segment 2a)
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TBM Platform........................ 36-in Steel Pipe...... 216 140 108 120 108 60 60 2 216 108
Jet Grouting Trestle................ 36-in Steel Pipe...... 204 100 20 120 184 50 40 3 170 68
Conveyor Trestle.................... 36-in Steel Pipe...... 84 100 8 120 76 50 40 3 70 28
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Total........................... ...................... 1,070 ........... ........... ........... ........... ........... ........... ........... ............ ............
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Planned in-water marine construction activities that have potential
to affect marine mammals will occur at the following locations in
Construction Areas 2 and 3 (Figure 2):
[ssquf] North Trestle-Bridges (Segment 1b);
[ssquf] Tunnel--North Island and South Island (Segment 2a);
[ssquf] South Trestle-Bridge (Segment 3a); and
[ssquf] Willoughby Bay Trestle-Bridges (Segment 3c).
Mitigation, monitoring, and reporting measures are described in
detail later in this document (please see Mitigation and Monitoring and
Reporting section).
A detailed description of the planned project is provided in the
Federal Register notice for the proposed IHA (85 FR 16194; March 20,
2020). Since that time, no changes have been made to the planned
construction activities. Therefore, a detailed description is not
provided here. Please refer to that Federal Register notice for the
description of the specific activity.
Comments and Responses
A notice of NMFS's proposal to issue an IHA to HRCP was published
in the Federal Register on March 20, 2020 (85 FR 16194). That notice
described, in detail, the project activity, the marine mammal species
that may be affected by the activity, and the anticipated effects on
marine mammals. During the 30-day public comment period, NMFS received
comments from the Marine Mammal Commission (Commission). The
Commission's letter is available online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities. Please see the letter for
full details of the recommendations and associated rationale.
Comment: The Commission commented that NMFS used incorrect proxy
source levels for impact installation of 30- and 54-in concrete piles
based on MacGillivray et al. (2007) and therefore underestimated the
various Level A and B harassment zones noted in Tables 11 and 12 of the
Federal Register notice of proposed IHA and Tables 2 and 3 in the draft
authorization. The Commission said that NMFS omitted the fact that
source levels for impact installation of 36-in
[[Page 48159]]
concrete piles were used as a proxy for the 30- and 54-in concrete
piles in the Federal Register notice (85 FR 16194; March 20, 2020).
Response: NMFS revised the source levels for 30- and 54-in concrete
piles to 193 dB SPLpeak (peak sound pressure level), 187 dB SPLrms
(sound pressure level, root mean square), and 177 decibels (dB) SEL
(sound exposure level) and therefore revised the Level A and Level B
harassment zones accordingly. However, the source level of 36-in
concrete piles were not used as a proxy for the 30- and 54-in concrete
piles.
Comment: The Commission stated that NMFS incorrectly noted that the
source levels for unattenuated and attenuated impact installation of
36-in piles originated from Chesapeake Tunnel Joint Venture (CTJV;
2018) and Department of the Navy (2015) rather than California
Department of Transportation (Caltrans; 2015) in Table 5 of the Federal
Register notice (85 FR 16194; March 20, 2020).
Response: NMFS recognizes this error and has made the correction in
this notice.
Comment: The Commission commented that NMFS indicated that three or
more hammers could be used simultaneously in the proposed IHA (85 FR
16194; March 20, 2020), but did not specify what the resulting source
levels would be if up to four vibratory hammers were used, what the
Level B harassment zone would be for the combined source level when
four hammers are used, whether multiple hammers of the same type would
be used at a given site, or what the worst-case scenario would be. The
Commission stated that extents of the Level B harassment zones, similar
to Table 3 in the draft authorization, must be specified to ensure the
appropriate zones are used to extrapolate the number of Level B
harassment takes during simultaneous use of vibratory hammers,
particularly since the monitoring zones are much smaller than the Level
B harassment zones.
Response: NMFS did provide the worst-case scenarios for when
multiple vibratory hammers (3) are used for 42-in steel piles. This was
described in Table 7 and 11. Table 11 assumes the max number of 42-in
steel piles that could be driven in a given day by multiple impact
hammers for two scenarios, three piles or two piles driven
simultaneously. It is not anticipated that four hammers would be used
simultaneously so the wording ``or more'' was an error and has been
omitted from the final notice. NMFS did not provide what the resulting
source levels would be for four hammers as the applicant indicated
three would be the maximum used. Therefore, no changes were made in
Table 13 for the calculated distances for Level B harassment in this
notice or Table 3 of the final IHA.
Comment: The Commission recommended using 162 rather than 161 dB re
1 [mu]Pa rms (1 micro Pascal, root mean square) at 10 m for vibratory
installation of 24-in piles and to re-estimate the Level A and B
harassment zones accordingly.
Response: NMFS believes that 161 dB re 1 [mu]Pa rms remains
appropriate for use in this circumstance and does not adopt the
recommendation to re-estimate the Level A and B harassment zones. The
source level is within 2 dB of the Commission's recommended
source level.
Comment: The Commission recommends that NMFS (1) have its experts
in underwater acoustics and bioacoustics review and finalize in the
next month its recommended proxy source levels for impact pile driving
of the various pile types and sizes, (2) compile and analyze the source
level data for vibratory pile driving of the various pile types and
sizes in the near term, and (3) ensure action proponents use consistent
and appropriate proxy source levels in all future rulemakings and
proposed IHA. If a subset of source level data is currently available
(i.e., vibratory pile driving of 24-in steel piles), those data should
be reviewed immediately.
Response: NMFS concurs with this recommendation and has prioritized
this effort. NMFS will conclude the process as soon as possible.
Comment: The Commission recommends that, for all authorizations
involving DTH drilling including HRCP's final IHA and proposed
rulemaking, NMFS use (1) source level data from Denes et al. (2019),
the Level A harassment thresholds for impulsive sources, and the
relevant expected operating parameters to estimate the extents of the
Level A harassment zones and (2) source level data from Denes et al.
(2016) and its Level B harassment threshold of 120-dB re 1 [mu]Pa rms
for continuous sources to estimate the extents of the Level B
harassment zones. If NMFS does not revise the Level B harassment zones
based on a more appropriate proxy source level and the Level B
harassment thresholds for continuous sources, the Commission recommends
that NMFS justify its decision not consider a DTH hammer to be an
impulsive, continuous sound source.
Response: NMFS did use the source level data from Denes et al.
(2019) and its Level A harassment thresholds for impulsive sources, and
the relevant expected operating parameters to estimate the extents of
the Level A harassment zones for DTH drilling in the proposed IHA (85
FR 16194; March 20, 2020). For the calculation of the Level B
harassment zone, NMFS concurs with the recommendation for this IHA and
made the change using the threshold of 120-dB re 1 [mu]Pa rms for
continuous sources to estimate the extents of the Level B harassment
zones using source level data from Denes et al. (2016). However, NMFS
does not agree that using Denes et al., 2019 as a source level is
necessarily appropriate for ``all authorizations'' and will evaluate
the best source level to use based on the operational details of future
projects and the source level data available at that time.
Comment: The Commission commented on the assumptions used by NMFS
regarding the efficacy of bubble curtains and NMFS adoption of a
standard 7 dB source level reduction when bubble curtains are use. The
Commission recommends that NMFS (1) consult with acousticians,
including those at University of Washington, Applied Physics Lab,
regarding the appropriate source level reduction factor to use to
minimize near-field (<100 m) and far-field (>100 m) effects on marine
mammals or (2) use the data NMFS has compiled regarding source level
reductions at 10 m for near-field effects and assume no source level
reduction for far-field effects for all relevant incidental take
authorizations. The Commission has made this recommendation, with
supporting justification and responses to NMFS's previous responses,
since mid-December 2019--NMFS has yet to address it. NMFS has directed
the Commission to NMFS's response from before the Commission made this
specific recommendation and to a Federal Register notice that does not
even pertain to NMFS. The Commission explicitly requests a detailed
response to both parts of this recommendation if NMFS does not follow
or adopt it, as required under section 202(d) of the MMPA.
Response: NMFS disagrees with the Commission regarding this issue,
and does not adopt the recommendation. The Commission has raised this
concern before and NMFS refers readers to our full response, which may
be found in a previous notice of issuance of an IHA (84 FR 64833,
November 25, 2019). NMFS will additionally provide a detailed
explanation of its decision
[[Page 48160]]
within 120 days, as required by section 202(d) of the MMPA.
Comment: The Commission recommends that NMFS require HRCP to (1)
conduct hydroacoustic monitoring (a) during impact installation of 54-
in concrete piles, (b) when multiple vibratory hammers are used
simultaneously and multiple DTH hammers are used simultaneously, (c)
when only one DTH hammer is used, and (d) when 36-in steel piles are
installed both with and without the bubble curtain, (2) ensure that
signal processing is conducted appropriately 28 for DTH drilling, and
(3) adjust the Level A and B harassment zones accordingly.
Response: The Commission states that it is ``apparent'' that HRCP
``should be'' conducting hydroacoustic monitoring, but fails to justify
the necessity of this recommended requirement, and does not address the
practicability of such a requirement. The Commission's recommendation
is based on the fact that source levels for 36-in piles are used as a
proxy for 54-in piles, as well as the following assertions: (1) Source
levels for DTH drilling have yet to be analyzed appropriately and (2)
the presumed 7-dB source level reduction associated with use of a
bubble curtain has yet to be proven. In addition, the Commission states
that the extents of the Level B harassment zones ``have not been
substantiated.'' NMFS disagrees with these points and does not adopt
the recommendation. It is common practice to use the best available
proxy data when data are not available for a particular pile type or
size and, while additional data may be useful, the use of a proxy does
not alone justify a requirement to conduct hydroacoustic monitoring.
Moreover, the Commission's assumption that source levels are
underestimated does not ultimately lead to a conclusion that the
evaluation of potential effects is similarly underestimated, given the
simple and conservative assumptions made in relation to expected
transmission loss. The source levels for DTH drilling are provided
through a hydroacoustic monitoring study for a similar project at a
nearby location. The Commission does not further explain its reasoning
on this point. The assumed 7-dB source level reduction attributed to
use of the bubble curtain was developed as a generic standard through
review of a large amount of data relating to use of bubble curtains
and, therefore, the Commission's suggestion that this reduction ``has
yet to be proven'' is incorrect. Further, the suggestion to conduct
this type of testing is inconsistent with the Commission's own
insistence that no reduction should be applied in any circumstances.
Finally, the suggestion that the size of the Level B harassment zones
has ``yet to be substantiated'' is nonsensical, as the project has yet
to begin, and is inconsistent with typical practice. The vast majority
of projects proceed with assumptions regarding zone size, and the
Commission does not adequately explain why the cost and logistical
considerations associated with hydroacoustic monitoring are warranted
in this case to ``substantiate'' the zone sizes.
The Commission points out that the HRCP plans to conduct more than
5 years of activities. This IHA only pertains to one year of those
activities. The applicant has requested a rulemaking/Letter of
Authorization for another 5 years of work to complete the overall
project. NMFS will consider the potential need for hydroacoustic
monitoring with the applicant as part of the rulemaking/Letter of
Authorization process.
Comment: The Commission noted its understanding that NMFS has
formed an internal committee to address perceived issues with
estimating Level A harassment zone sizes and is consulting with
external acousticians and modelers as well. In the absence of relevant
recovery time data for marine mammals, the Commission continues to
believe that animat modeling that considers various operational and
animal scenarios should be used to inform the appropriate accumulation
time and could be incorporated into NMFS's user spreadsheet that
currently estimates the Level A harassment zones. The Commission
recommends that NMFS continue to make this issue a priority to resolve
in the near future and consider incorporating animat modeling into its
user spreadsheet.
Response: NMFS concurs with this recommendation and has prioritized
the issue.
Comment: The Commission recommends that NMFS increase the number of
takes from 261 to at least 3,588 takes of harbor seals, equating to at
least 753 Level A harassment and 2,835 Level B harassment takes of
harbor seals.
Response: NMFS disagrees with the Commission's recommendation and
does not adopt it. In the proposed IHA, NMFS proposed 55 takes by Level
A harassment and 206 takes by Level B harassment. During the comment
period, NMFS informally discussed with the Commission increasing harbor
seals takes using 8 seals/day multiplied by 156 days for a total of
1,248 takes. The Commission did not indicate any opposition to this new
estimate. That said, NMFS has determined that it will use the average
5-year daily count of 13.6 seals (Jones et al., 2020) in its take
estimate to be more conservative than the proposed IHA as fully
described in the Estimated Take section.
Comment: The Commission recommends that NMFS use the Chesapeake Bay
density of 1.38 dolphins/square kilometer (km\2\) from Engelhaupt et
al. (2016) and (1) the Level B harassment ensonified area of 131.4
km\2\ west of the HRBT and 312 days of activities, (2) the Level B
harassment ensonified area of 221.46 km\2\ for vibratory installation
of 42-in steel piles at the South Trestle and 7 days of activities, (3)
the Level B harassment ensonified area associated of 27.65 km\2\ for
vibratory installation of 24-in steel piles at the South Trestle and 3
days of activities, and (4) the Level B harassment ensonified area
associated of 0.87 km\2\ for impact installation of 54-in concrete
piles at the South Trestle and 22 days of activities to increase the
numbers of Level B harassment takes of bottlenose dolphins from 6,343
to 58,856.
Response: NMFS has accepted the Commission's recommendation and
will use the dolphin density of 1.38 dolphins/km\2\ from Engelhaupt et
al. (2016) to estimate take of bottlenose dolphins as described in the
Estimated Take section. However, NMFS notes the Commission's statement
that the use of bottlenose dolphin data in the notice of proposed IHA
``appears to be an attempt to reduce the number of takes rather than an
effort to use the best available data.'' The Commission's statement is
both inappropriate and incorrect, and NMFS strongly objects to the
Commission's attempt to interpret intent.
Comment: The Commission recommends that NMFS ensure HRCP keeps a
running tally of the total takes, based on observed and extrapolated
takes, for Level A and B harassment.
Response: We agree that HRCP must ensure they do not exceed
authorized takes, but do not concur with the recommendation. NMFS is
not responsible for ensuring that HRCP does not operate in violation of
an issued IHA.
Comment: The Commission recommends that NMFS require HRCP to use at
least (1) one protected species observer (PSO) to monitor the shut-down
zones for each hammer that is in use at each site, (2) one PSO to
monitor the Level B harassment zones during vibratory installation of
piles at Willoughby Bay and to be located near the entrance of the Bay
to observe
[[Page 48161]]
animals entering and exiting the Level B harassment zone, (3) one PSO
to monitor the Level A and B harassment zones during impact
installation of 30- and 54-in piles at North and South Trestle, (4)
three PSOs to monitor the Level B harassment zones during vibratory
pile driving of 24-in piles at South Trestle, one PSO on the Hampton
side and one on the Norfolk side of Chesapeake Bay to the east of HRBT
and one PSO on the Hampton side to the west of HRBT, (5) four PSOs to
monitor the Level B harassment zones during vibratory pile driving of
42-in piles at South Trestle, one on the Hampton side and one on the
Norfolk side of Chesapeake Bay to the east of HRBT and one on the
Hampton side and one on the Norfolk side to the west of HRBT, and (6)
four PSOs to monitor the Level B harassment zones during vibratory pile
driving and/or DTH drilling of 36- and 42-in piles and during
simultaneous use of multiple hammers at North Trestle, North Island,
and South Island, two on the Hampton side and two on the Norfolk side
to the west of HRBT.
Response: NMFS appreciates the Commission's recommendations for PSO
locations. As previously described in the proposed IHA, monitoring
locations will provide an unobstructed view of all water within the
shutdown zone and as much of the Level B harassment zone as possible
for pile driving activities. However, after further discussion with the
applicant, HRCP will station between one and four PSOs at locations
offering the best available views of the Level A and Level B monitoring
zones during in-water pile driving at the North Trestle, North Island,
South Trestle, and South Island. When and where able, as determined by
the PSO or Lead PSO when multiple observers are required, Level A and
Level B harassment zones may be monitored for multiple pile driving
locations by the same individual PSO. HRCP will be required to station
between one and two PSOs at locations offering the best available views
of the Level A and Level B monitoring zones during in-water pile
driving at Willoughby Bay.
Comment: The Commission recommends that NMFS include in (1) section
3 of the final authorization the requirement that HRCP conduct pile-
driving activities during daylight hours only and (2) section 4 of the
final authorization the requirement that, if the entire shut-down
zone(s) is not visible due to fog or heavy rain, HRCP delay or cease
pile-driving and -removal activities until the zone(s) is visible.
Response: NMFS does not concur and does not adopt the
recommendation. The work is anticipated to be conducted during daylight
hours. However, if work needs to extend into the night, work may only
be conducted under conditions where there is full visibility of the
shutdown zone or where stopping ongoing work would otherwise create an
unsafe work condition. In addition, the IHA requires that work must be
conducted during conditions of good visibility. If poor environmental
conditions restrict full visibility of the shutdown zone, pile
installation must be delayed. Poor visibility implies a condition that
would occur under fog or heavy rain.
Comment: The Commission recommends that NMFS include in all draft
and final IHA the explicit requirements to cease activities if a marine
mammal is injured or killed during the specified activities until NMFS
reviews the circumstances involving any injury or death that is likely
attributable to the activities and determines what additional measures
are necessary to minimize additional injuries or deaths.
Response: NMFS concurs with the Commission's recommendation as it
relates to this IHA and has added the referenced language to the
Monitoring and Reporting section of this notice and the Reporting
section of the issued IHA. We will continue to evaluate inclusion of
this language in future IHAs.
Comment: The Commission reiterates programmatic recommendations
regarding NMFS' potential use of the renewal mechanism for one-year
IHAs.
Response: NMFS does not agree with the Commission and, therefore,
does not adopt the Commission's recommendation. NMFS will provide a
detailed explanation of its decision within 120 days, as required by
section 202(d) of the MMPA.
Comment: The Commission recommends that NMFS (1) publish a revised
proposed authorization for public comment, (2) consult with HRCP
regarding the numerous issues raised in this letter and direct the
applicant to revise its letter of authorization application
accordingly, and (3) refrain from publishing for public comment
proposed IHAs and proposed rules based on underlying applications that
contain omissions, errors, and inconsistencies and instead return such
applications to action proponents as incomplete.
Response: NMFS does not agree with the Commission and does not
adopt the recommendation. NMFS disagrees that the information presented
in association with the proposed IHA was insufficient to facilitate
public review and comment, as the Commission states. What the
Commission claims are ``omissions, errors, and inconsistencies'' are,
for the most part, differences of opinion on how available data should
be applied to our analysis and, in each case, we have presented reasons
why we disagree with specific recommendations. If we did agree that
there actually was an error or that the Commission's logic is more
appropriate to implement, we have made the recommended changes. We note
many of the recommendations by the Commission are detail-oriented and,
in NMFS' view, do not provide additional conservation value or
meaningfully influence any of the analyses underlying the necessary
findings. NMFS strongly disagrees with the Commission's suggestion that
NMFS' negligible impact and least practicable adverse impact
determinations may be invalid, and we note that the Commission does not
provide any information supporting this comment, whether NMFS retained
the take numbers and mitigation requirements from the proposed IHA or
adopted those recommended by the Commission. Overall, there are no
substantial changes or new information that would lead us to reach any
other conclusions regarding the impact to marine mammals. For these
reasons, NMFS is not republishing a notice of proposed IHA.
Changes From the Proposed IHA to the Final IHA
Changes were made to the source level for 30- and 54-in concrete
piles during impact pile driving. Therefore, Level A and Level B
harassment zones were recalculated and corrected in Tables 11 and 12
and in the final authorization. The Level B harassment zone was also
recalculated for DTH drilling for 36-in piles, reflecting use of the
continuous noise, 120-dB threshold. Appropriate corrections were made
to Table 12 and in the final authorization. Changes to the estimated
take numbers for harbor seals and bottlenose dolphins were made, as
recommended by the Commission. For mitigation and monitoring,
clarification of the timing of the work as well as PSO locations were
also made.
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://
[[Page 48162]]
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 2 lists all species or stocks for which take is expected and
authorized for this action, and summarizes information related to the
population or stock, including regulatory status under the MMPA and ESA
and potential biological removal (PBR), where known. For taxonomy, we
follow Committee on Taxonomy (2019). 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 United States Atlantic and Gulf of Mexico Marine Mammal SARs.
All values presented in Table 2 are the most recent available at the
time of publication and are available in the draft 2019 SARs (https://www.fisheries.noaa.gov/national/marine-mammal-protection/draft-marine-mammal-stock-assessment-reports).
Table 2--Marine Mammal Species Likely To Occur Near the Project Area
--------------------------------------------------------------------------------------------------------------------------------------------------------
Stock abundance (CV,
Common name Scientific name Stock ESA/MMPA status; Nmin, most recent PBR Annual M/
strategic (Y/N) \1\ abundance survey) \2\ SI \3\
--------------------------------------------------------------------------------------------------------------------------------------------------------
Order Cetartiodactyla--Cetacea--Superfamily Mysticeti (baleen whales)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Balaenopteridae (rorquals):
Humpback whale \4\.............. Megaptera novaeangliae. Gulf of Maine......... -,-; N 896 (.42; 896; 2012).. 14.6 9.7
--------------------------------------------------------------------------------------------------------------------------------------------------------
Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Delphinidae:
Bottlenose dolphin.............. Tursiops spp........... Western North Atlantic -,-; Y 6,639 (0.41; 4,759; 48 6.1-13.2
(WNA) Coastal, 2011).
Northern Migratory.
WNA Coastal, Southern -,-; Y 3,751 (0.06; 2,353; 23 0-14.3
Migratory. 2011).
Northern North -,-; Y 823 (0.06; 782; 2013). 7.8 0.8-18.2
Carolina Estuarine
System (NNCES).
Family Phocoenidae (porpoises):
Harbor porpoise................. Phocoena phocoena...... Gulf of Maine/Bay of -, -; N 79,833 (0.32; 61,415; 706 256
Fundy. 2011).
--------------------------------------------------------------------------------------------------------------------------------------------------------
Order Carnivora--Superfamily Pinnipedia
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Phocidae (earless seals):
Harbor seal..................... Phoca vitulina......... WNA................... -; N 75,834 (0.1; 66,884, 2,006 345
2012).
Gray seal....................... Halichoerus grypus..... WNA................... -; N 27,131 (0.19, 23,158, 1,359 5,688
2016).
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Endangered Species Act (ESA) status: Endangered (E), Threatened (T)/MMPA status: Depleted (D). A dash (-) indicates that the species is not listed
under the ESA or designated as depleted under the MMPA. Under the MMPA, a strategic stock is one for which the level of direct human-caused mortality
exceeds PBR or which is determined to be declining and likely to be listed under the ESA within the foreseeable future. Any species or stock listed
under the ESA is automatically designated under the MMPA as depleted and as a strategic stock.
\2\ NMFS marine mammal stock assessment reports online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessment-reports. CV is coefficient of variation; Nmin is the minimum estimate of stock abundance. In some cases, CV is not applicable.
\3\ These values, found in NMFS's SARs, represent annual levels of human-caused mortality plus serious injury from all sources combined (e.g.,
commercial fisheries, ship strike). Annual M/SI often cannot be determined precisely and is in some cases presented as a minimum value or range. A CV
associated with estimated mortality due to commercial fisheries is presented in some cases.
\4\ 2018 U.S. Atlantic SAR for the Gulf of Maine feeding population lists a current abundance estimate of 896 individuals. However, we note that the
estimate is defined on the basis of feeding location alone (i.e., Gulf of Maine) and is therefore likely an underestimate.
As indicated above, all five species (with seven managed stocks) in
Table 2, temporally and spatially co-occur with the activity to the
degree that take is reasonably likely to occur, and therefore
authorized. All species that could potentially occur in the planned
project area are included in Table 3-1 of the application. While North
Atlantic right whales (Eubalaena glacialis), minke whales (Balaenoptera
acutorostrata acutorostrata), and fin whales (Balaenoptera physalus)
have been documented in the area, the temporal and/or spatial
occurrence of these whales is such that take is not expected to occur,
and they are not discussed further. Detailed descriptions of marine
mammals in the project area were provided in the Federal Register
notice for the proposed IHA (85 FR 16194; March 20, 2020).
Marine Mammal Hearing
Hearing is the most important sensory modality for marine mammals
underwater, and exposure to anthropogenic sound can have deleterious
effects. To appropriately assess the potential effects of exposure to
sound, it is necessary to understand the frequency ranges marine
mammals are able to hear. Current data indicate that not all marine
mammal species have equal hearing capabilities (e.g., Richardson et
al., 1995; Wartzok and Ketten, 1999; Au and Hastings, 2008). To reflect
this, Southall et al. (2007) recommended that marine mammals be
[[Page 48163]]
divided into functional hearing groups based on directly measured or
estimated hearing ranges on the basis of available behavioral response
data, audiograms derived using auditory evoked potential techniques,
anatomical modeling, and other data. Note that no direct measurements
of hearing ability have been successfully completed for mysticetes
(i.e., low-frequency cetaceans). Subsequently, NMFS (2018) described
generalized hearing ranges for these marine mammal hearing groups.
Generalized hearing ranges were chosen based on the approximately 65 dB
threshold from the normalized composite audiograms, with the exception
for lower limits for low-frequency cetaceans where the lower bound was
deemed to be biologically implausible and the lower bound from Southall
et al. (2007) retained. Marine mammal hearing groups and their
associated hearing ranges are provided in Table 3.
Table 3--Marine Mammal Hearing Groups
[NMFS, 2018]
------------------------------------------------------------------------
Hearing group Generalized hearing range *
------------------------------------------------------------------------
Low-frequency (LF) cetaceans (baleen 7 Hz to 35 kHz.
whales).
Mid-frequency (MF) cetaceans (dolphins, 150 Hz to 160 kHz.
toothed whales, beaked whales, bottlenose
whales).
High-frequency (HF) cetaceans (true 275 Hz to 160 kHz.
porpoises, Kogia, river dolphins,
cephalorhynchid, Lagenorhynchus cruciger &
L. australis).
Phocid pinnipeds (PW) (underwater) (true 50 Hz to 86 kHz.
seals).
Otariid pinnipeds (OW) (underwater) (sea 60 Hz to 39 kHz.
lions and fur seals).
------------------------------------------------------------------------
* Represents the generalized hearing range for the entire group as a
composite (i.e., all species within the group), where individual
species' hearing ranges are typically not as broad. Generalized
hearing range chosen based on ~65 dB threshold from normalized
composite audiogram, with the exception for lower limits for LF
cetaceans (Southall et al. 2007) and PW pinniped (approximation).
The pinniped functional hearing group was modified from Southall et
al. (2007) on the basis of data indicating that phocid species have
consistently demonstrated an extended frequency range of hearing
compared to otariids, especially in the higher frequency range
(Hemil[auml] et al., 2006; Kastelein et al., 2009; Reichmuth and Holt,
2013).
For more detail concerning these groups and associated frequency
ranges, please see NMFS (2018) for a review of available information.
Five marine mammal species (three cetacean and two phocid pinniped)
have the reasonable potential to co-occur with the planned survey
activities. Please refer to Table 2. Of the cetacean species that may
be present, one is classified as low-frequency (humpback whale), one is
classified as mid-frequency (bottlenose dolphin) and one is classified
as high-frequency (harbor porpoise).
Potential Effects of Specified Activities on Marine Mammals and Their
Habitat
The effects from underwater noise from the planned pile driving and
removal activities have the potential to result in Level A and Level B
harassment of marine mammals in the vicinity of the project area. The
Federal Register notice for the proposed IHA (85 FR 16194; March 20,
2020) included a discussion of the effects of anthropogenic noise on
marine mammals and their habitat, therefore that information is not
repeated here; please refer to that Federal Register notice (85 FR
16194; March 20, 2020) for that information.
Estimated Take
This section provides an estimate of the number of incidental takes
authorized through this IHA, which will inform 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).
Take of marine mammals incidental to HRCP's pile driving and
removal activities could occur by Level A and Level B harassment, as
pile driving has the potential to result in disruption of behavioral
patterns for individual marine mammals. The planned mitigation and
monitoring measures are expected to minimize the severity of such
taking to the extent practicable. 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 NMFS believes the best available science
indicates marine mammals will be behaviorally harassed or incur some
degree of permanent hearing impairment; (2) the area or volume of water
that will be ensonified above these levels in a day; (3) the density or
occurrence of marine mammals within these ensonified areas; and, (4)
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). Below, we describe the
factors considered here in more detail and present the authorized take
estimates for the IHA.
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 harassment) or to incur
permanent threshold shift (PTS) of some degree (equated to Level A
harassment).
Level B Harassment--Though significantly driven by received level,
the onset of behavioral disturbance from anthropogenic noise exposure
is also informed to varying degrees by other factors related to the
source (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
[[Page 48164]]
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) for continuous (e.g., vibratory pile-driving,
drilling) and above 160 dB re 1 [mu]Pa (rms) for non-explosive
impulsive (e.g., impact pile driving seismic airguns) or intermittent
(e.g., scientific sonar) sources. The planned activities include the
use of continuous, non-impulsive (vibratory pile driving) and impulsive
(impact pile driving) sources and therefore, the 120 and 160 dB re 1
[mu]Pa (rms) are applicable. The DTH hammer is considered a continuous
noise source for purposes of evaluating potential behavioral impacts.
Level A Harassment--NMFS' Technical Guidance for Assessing the
Effects of Anthropogenic Sound on Marine Mammal Hearing (Version 2.0)
(Technical Guidance, 2018) identifies dual criteria to assess auditory
injury (Level A harassment) to five different marine mammal groups
(based on hearing sensitivity) as a result of exposure to noise. The
technical guidance identifies the received levels, or thresholds, above
which individual marine mammals are predicted to experience changes in
their hearing sensitivity for all underwater anthropogenic sound
sources, and reflects the best available science on the potential for
noise to affect auditory sensitivity by:
[ssquf] Dividing sound sources into two groups (i.e., impulsive and
non- impulsive) based on their potential to affect hearing sensitivity;
[ssquf] Choosing metrics that best address the impacts of noise on
hearing sensitivity, i.e., sound pressure level (peak SPL) and sound
exposure level (SEL) (also accounts for duration of exposure); and
[ssquf] Dividing marine mammals into hearing groups and developing
auditory weighting functions based on the science supporting that not
all marine mammals hear and use sound in the same manner.
These thresholds were developed by compiling and synthesizing the
best available science, and are provided in Table 4 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-technicalguidance. The planned
activity includes the use of impulsive (impact pile driving) and non-
impulsive (vibratory pile driving) sources. The DTH hammer is
considered an impulsive noise source for purposes of evaluating
potential auditory impacts.
Table 4--Thresholds Identifying the Onset of Permanent Threshold Shift
----------------------------------------------------------------------------------------------------------------
PTS onset acoustic thresholds * (received level)
Hearing group ------------------------------------------------------------------------
Impulsive Non-impulsive
----------------------------------------------------------------------------------------------------------------
Low-Frequency (LF) Cetaceans........... Cell 1: Lpk,flat: 219 dB; Cell 2: LE,LF,24h: 199 dB.
LE,LF,24h: 183 dB.
Mid-Frequency (MF) Cetaceans........... Cell 3: Lpk,flat: 230 dB; Cell 4: LE,MF,24h: 198 dB.
LE,MF,24h: 185 dB.
High-Frequency (HF) Cetaceans.......... Cell 5: Lpk,flat: 202 dB; Cell 6: LE,HF,24h: 173 dB.
LE,HF,24h: 155 dB.
Phocid Pinnipeds (PW) (Underwater)..... Cell 7: Lpk,flat: 218 dB; Cell 8: LE,PW,24h: 201 dB.
LE,PW,24h: 185 dB.
Otariid Pinnipeds (OW) (Underwater).... Cell 9: Lpk,flat: 232 dB; Cell 10: LE,OW,24h: 219 dB.
LE,OW,24h: 203 dB.
----------------------------------------------------------------------------------------------------------------
* Dual metric acoustic thresholds for impulsive sounds: Use whichever results in the largest isopleth for
calculating PTS onset. If a non-impulsive sound has the potential of exceeding the peak sound pressure level
thresholds associated with impulsive sounds, these thresholds should also be considered.
Note: Peak sound pressure (Lpk) has a reference value of 1 [micro]Pa, and cumulative sound exposure level (LE)
has a reference value of 1[micro]Pa\2\s. In this Table, thresholds are abbreviated to reflect American
National Standards Institute standards (ANSI 2013). However, peak sound pressure is defined by ANSI as
incorporating frequency weighting, which is not the intent for this Technical Guidance. Hence, the subscript
``flat'' is being included to indicate peak sound pressure should be flat weighted or unweighted within the
generalized hearing range. The subscript associated with cumulative sound exposure level thresholds indicates
the designated marine mammal auditory weighting function (LF, MF, and HF cetaceans, and PW and OW pinnipeds)
and that the recommended accumulation period is 24 hours. The cumulative sound exposure level thresholds could
be exceeded in a multitude of ways (i.e., varying exposure levels and durations, duty cycle). When possible,
it is valuable for action proponents to indicate the conditions under which these acoustic thresholds will be
exceeded.
Ensonified Area
Here, we describe operational and environmental parameters of the
activity that will feed into identifying the area ensonified above the
acoustic thresholds, which include source levels and transmission loss
coefficient.
Sound Propagation
Transmission loss (TL) is the decrease in acoustic intensity as an
acoustic pressure wave propagates out from a source. TL parameters vary
with frequency, temperature, sea conditions, current, source and
receiver depth, water depth, water chemistry, and bottom composition
and topography. The general formula for underwater TL is:
TL = B * log10(R1/R2),
Where:
B = transmission loss coefficient (assumed to be 15)
R1 = the distance of the modeled SPL from the driven
pile, and
R2 = the distance from the driven pile of the initial
measurement.
This formula neglects loss due to scattering and absorption, which
is assumed to be zero here. The degree to which underwater sound
propagates away from a sound source is dependent on a variety of
factors, most notably the water bathymetry and presence or absence of
reflective or absorptive conditions including in-water structures and
sediments. 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)). As is
common practice in coastal waters, here we assume practical spreading
loss (4.5 dB reduction in sound level for each doubling of distance).
Practical spreading is a compromise that is often
[[Page 48165]]
used under conditions where water depth increases as the receiver moves
away from the shoreline, resulting in an expected propagation
environment that would lie between spherical and cylindrical spreading
loss conditions.
Sound Source Levels
The intensity of pile driving sounds is greatly influenced by
factors such as the type of piles, hammers, and the physical
environment in which the activity takes place. There are source level
measurements available for certain pile types and sizes from the
similar environments recorded from underwater pile driving projects
(e.g., Caltrans 2015) that were used to determine reasonable sound
source levels likely result from the HRCP's pile driving and removal
activities (Table 5). Bubble curtains will be used during impact pile
driving of 36-in steel piles at the Jet Grouting Trestle in water
depths greater than 6 m (20 ft). Therefore, a 7dB reduction of the
sound source level will be implemented (Table 5).
Table 5--Predicted Sound Source Levels for All Pile Types
----------------------------------------------------------------------------------------------------------------
Method and pile type Sound source level at 10 meters
--------------------------------------------------------------------------------------- Source
Vibratory hammer dB rms
----------------------------------------------------------------------------------------------------------------
42-in steel pile...................... \a\ 168 City and Borough of
Sitka Department of
Public Works 2017.
36-in steel pile...................... \b\ 167 DoN 2015.
24-in steel pile...................... \c\161 DoN 2015.
----------------------------------------------------------------------------------------------------------------
Down-the-hole hammer dB rms dB SEL dB peak
----------------------------------------------------------------------------------------------------------------
All pile sizes...................... 180 164 190 Denes et al., 2019.
----------------------------------------------------------------------------------------------------------------
Impact hammer dB rms dB SEL dB peak
----------------------------------------------------------------------------------------------------------------
36-in steel pile.................... 193 183 210 Caltrans, 2015.
36-in steel pile, attenuated *...... 186 176 203 Caltrans, 2015.
54-in concrete cylinder pile........ 187 177 193 MacGillivray et al.,
2007.
30-in concrete square pile.......... 187 177 193 MacGillivray et al.,
2007.
24-in concrete square pile.......... 176 166 188 Caltrans, 2015.
----------------------------------------------------------------------------------------------------------------
SEL = sound exposure level; dB peak = peak sound level; rms = root mean square; DoN = Department of the Navy.
* Sound source levels (SSLs) are a 7 dB reduction for the usage of a bubble curtain.
\a\ The SPL rms value of 168 dB is within 2 dB of Caltrans (2015) at 170 dB rms for 42-in piles.
\b\ The SPL rms value of 167 is within 3 dB of Caltrans (2015) at 170 dB rms; however, the DoN (2015)
incorporates a larger dataset and is better suited to this project.
\c\ There is no Caltrans (2015) data available for this pile size. Caltrans is 155 dB rms for 12-in pipe pile or
170 dB rms for 36-in steel piles. The value of 161 dB rms has been also used in previous IHAs (e.g., 82 FR
31400, July 6, 2017; 83 FR 12152, March 20, 2018; 84 FR 22453, May 17, 2019; and 84 FR 34134, July 17, 2019).
During pile driving installation activities, there may be times
when multiple construction sites are active and hammers are used
simultaneously. For impact hammering, it is unlikely that the two
hammers would strike at the same exact instant, and therefore, the
sound source levels will not be adjusted regardless of the distance
between the hammers. For this reason, multiple impact hammering is not
discussed further. For simultaneous vibratory hammering, 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. When two continuous noise sources, such as vibratory hammers,
have overlapping sound fields, there is potential for higher sound
levels than for non-overlapping sources. When two or more vibratory
hammers are used simultaneously, and the sound field of one source
encompasses the sound field of another source, the sources are
considered additive and combined using the following rules (see Table
6): For addition of two simultaneous vibratory hammers, the difference
between the two SSLs is calculated, and if that difference is between 0
and 1 dB, 3 dB are added to the higher SSL; if difference is between 2
or 3 dB, 2 dB are added to the highest SSL; if the difference is
between 4 to 9 dB, 1 dB is added to the highest SSL; and with
differences of 10 or more decibels, there is no addition.
Table 6--Rules for Combining Sound Levels Generated During Pile Installation
----------------------------------------------------------------------------------------------------------------
Hammer types Difference in SSL Level A zones Level B zones
----------------------------------------------------------------------------------------------------------------
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 2018b.
Note: dB = decibels; SSL = sound source level.
[[Page 48166]]
For simultaneous usage of three or more continuous sound sources,
such as vibratory hammers, the three overlapping sources with the
highest SSLs are identified. Of the three highest SSLs, the lower two
are combined using the above rules, then the combination of the lower
two is combined with the highest of the three. For example, with
overlapping isopleths from 24-, 36-, and 42-in diameter steel pipe
piles with SSLs of 161, 167, and 168 dB rms respectively, the 24- and
36-inwould be added together; given that 167-161 = 6 dB, then 1 dB is
added to the highest of the two SSLs (167 dB), for a combined noise
level of 168 dB. Next, the newly calculated 168 dB is added to the 42-
in steel pile with SSL of 168 dB. Since 168-168 = 0 dB, 3 dB is added
to the highest value, or 171 dB in total for the combination of 24-,
36-, and 42-in steel pipe piles (NMFS 2018b; WSDOT 2018). As described
in Table 6, decibel addition calculations were carried out for all
possible combinations of vibratory installation of 24-, 36- and 42-in
steel pipe piles throughout the project area (Table 7).
[GRAPHIC] [TIFF OMITTED] TN10AU20.002
Level A Harassment
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 Level A harassment take. However, these tools offer the
best way to predict appropriate isopleths when more sophisticated 3D
modeling methods are not available, and NMFS continues to develop ways
to quantitatively refine these tools, and will qualitatively address
the output where appropriate. For stationary sources (such as from
vibratory pile driving), 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 incur PTS. Inputs used in the
User Spreadsheet (Tables 8 through 10), and the resulting isopleths are
reported below (Table 11).
In the chance that multiple vibratory hammers would be operated
simultaneously, to simplify implementation of Level A harassment zones,
the worst-case theoretical scenarios were calculated for the longest
anticipated duration of the largest pile size (42-in steel pile) that
could be installed within a day (see Table 8). However, it would be
unlikely that six sets of three piles could be installed in synchrony,
but more likely that installations of piles would overlap by a few
minutes at the beginning or end, throughout the day, so that during a
12-hour construction shift, there would be periods of time when zero,
one, two, three, or more hammers would be working.
Table 8--NMFS Technical Guidance (2018) User Spreadsheet Input To Calculate PTS Isopleths for Vibratory Pile Driving for All Locations
[User spreadsheet input--vibratory pile driving spreadsheet tab A.1 vibratory pile driving used]
--------------------------------------------------------------------------------------------------------------------------------------------------------
42-in steel piles 42-in steel piles
24-in steel 36-in steel 36-in steel 42-in steel (multiple hammer event-- (multiple hammer
piles piles piles (at TBM piles 3 hammers event--2 hammers
platform) simultaneously) simultaneously)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Source Level (RMS SPL)............... 161 167 167 168 173..................... 171.
Weighting Factor Adjustment (kHz).... 2.5 2.5 2.5 2.5 2.5..................... 2.5.
Number of piles within 24-hr period.. 6 3 2 6 6....................... 9.
(3 piles installed (2 piles installed
simultaneously, 6 simultaneously, 9
piling events). piling events).
Duration to drive a single pile (min) 30 50 60 30 30...................... 30.
Propagation (xLogR).................. 15 15 15 15 15...................... 15.
[[Page 48167]]
Distance of source level measurement 10 10 10 10 10...................... 10.
(meters).
--------------------------------------------------------------------------------------------------------------------------------------------------------
Table 9--NMFS Technical Guidance (2018) User Spreadsheet Input To
Calculate PTS Isopleths for Impact Pile Driving for the Jet Grouting
Trestle With and Without a Bubble Curtain
[User spreadsheet input--impact pile driving spreadsheet tab E.1-2
impact pile driving used for jet grouting trestle]
------------------------------------------------------------------------
36-in steel
36-in steel piles
piles (attenuated)
------------------------------------------------------------------------
Source Level (SEL)...................... 183 * 176
Weighting Factor Adjustment (kHz)....... 2 2
Number of piles within 24-hr period..... 3 3
Number of strikes per pile.............. 40 40
Propagation (xLogR)..................... 15 15
Distance of source level measurement 10 10
(meters)+..............................
------------------------------------------------------------------------
* The attenuated piles account for a 7dB reduction from the use of a
bubble curtain.
Table 10--NMFS Technical Guidance (2018) User Spreadsheet Input To Calculate PTS Isopleths for Impact Pile Driving and DTH Drilling
[User spreadsheet input--impact pile driving spreadsheet tab E.1-2 impact pile driving]
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
North North trestle, willoughby bay, and South island DTH
trestle south trestle test pile program -----------------------------------------------------------------------------
---------------------------------------------------- North shore Jet
TBM Conveyor TBM work grouting Conveyor
36-in steel 24-in 30-in 54-in platform trestle 36- platform trestle 36- trestle 36- trestle 36-
piles concrete concrete concrete 36-in steel in steel 36-in steel in steel in steel in steel
square square cylinder piles piles piles piles piles piles
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Source Level (SEL)............................................ 183 166 177 177 183 183 164 164 164 164
Weighting Factor Adjustment (kHz)............................. 2 2 2 2 2 2 2 2 2 2
Number of piles within 24-hr period........................... 3 1 1 1 2 3 2 3 3 3
Number of strikes per pile.................................... 40 2,100 2,100 2,100 60 40 50,400 50,400 50,400 50,400
Propagation (xLogR)........................................... 15 15 15 15 15 15 15 15 15 15
Distance of source level measurement (meters)+................ 10 10 10 10 10 10 10 10 10 10
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Table 11--Level A Harassment Isopleths for Both Vibratory and Impact Pile Driving
--------------------------------------------------------------------------------------------------------------------------------------------------------
User spreadsheet output PTS isopleths (meters) PTS isopleths (km\2\)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Level A harassment Level A harassment
-------------------------------------------------------------------------------------------------------
Pile type/activity Sound source Low- Mid- High- Low- Mid- High-
level at 10 m frequency frequency frequency Phocid frequency frequency frequency Phocid
cetaceans cetaceans cetaceans cetaceans cetaceans cetaceans
--------------------------------------------------------------------------------------------------------------------------------------------------------
Vibratory Pile Driving
--------------------------------------------------------------------------------------------------------------------------------------------------------
24-in steel pile installation 161 dB SPL...... 15 2 21 9 <0.01
(All Locations).
---------------------------------------------------
36-in steel pile installation 167 dB SPL...... 32 3 47 20 <0.01
(All Locations).
---------------------------------------------------
36-in steel pile installation 167 dB SPL...... 28 3 41 17 <0.01
(TMB Platform).
---------------------------------------------------
42-in steel pile installation 168 dB SPL...... 42 4 62 26 <0.10
(All Locations).
--------------------------------------------------------------------------------------------------------------------------------------------------------
Impact Pile for the Jet Grouting Trestle
--------------------------------------------------------------------------------------------------------------------------------------------------------
36-in steel pile installation. 183 dB SEL/193 243 9 290 130 0.11 <0.01 0.16 <0.10
SPL.
36-in steel pile installation 176 dB SEL/186 83 3 99 45 0.014 <0.001 0.20 <0.01
(attenuated). SPL.
--------------------------------------------------------------------------------------------------------------------------------------------------------
[[Page 48168]]
Impact Pile Driving North Trestle
--------------------------------------------------------------------------------------------------------------------------------------------------------
36-in steel pile installation 183 dB SEL/193 243 9 290 130 0.19 <0.001 0.26 0.05
(North Shore Work Trestle). SPL.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Impact Pile Driving for North Trestle, Willoughby Bay, and South Trestle Test Pile Program
--------------------------------------------------------------------------------------------------------------------------------------------------------
24-in concrete square pile 166 dB SEL/190 121 5 144 65 0.05 <0.001 0.07 0.01
installation/removal. SPL.
30-in concrete square pile 177 dB SEL/187 652 23.2 776.6 348.9 1.335 0.002 1.8947 0.3824
installation/removal. SPL.
54-in concrete square pile 177 dB SEL/187 652 23.2 776.6 348.9 1.335 0.002 1.8947 0.3824
installation/removal. SPL.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Impact Pile Driving for South Island
--------------------------------------------------------------------------------------------------------------------------------------------------------
36-in steel pile installation 183 dB SEL/193 243 9 290 130 0.11 <0.001 0.16 <0.10
(TBM Platform). SPL.
36-in steel pile installation 183 dB SEL/193 243 9 290 130 0.11 <0.001 0.16 <0.10
(Conveyor Trestle). SPL.
--------------------------------------------------------------------------------------------------------------------------------------------------------
DTH Drilling
--------------------------------------------------------------------------------------------------------------------------------------------------------
36-in steel pile installation 164 SEL/180 dB 1,171 42 1,395 627 2.437 <0.01 3.446 0.704
(TBM Platform). SPL.
36-in steel pile installation 164 SEL/180 dB 1,534 55 1,827 821 3.615 <0.01 4.790 1.548
(North Shore Work Trestle). SPL.
36-in steel pile installation 164 SEL/180 dB 1,534 55 1,827 821 3.615 <0.01 5.908 1.548
(Jet Grouting Trestle). SPL.
36-in steel pile installation 164 SEL/180 dB 1,534 55 1,827 821 3.615 <0.01 5.908 1.548
(Conveyor Trestle). SPL.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Multiple Hammers--Vibratory Pile Driving (if occurs) *
--------------------------------------------------------------------------------------------------------------------------------------------------------
42-in steel pile installation 173 dB SPL...... 89.6 7.9 132.5 54.5 0.025 0.0001 0.055 0.009
(assumes 3 piles installed
simultaneously, 6 piling
events * 30 minutes each
event in a 24-hr period).
42-in steel pile installation 171 dB SPL...... 86.4 7.7 127.8 52.5 0.023 0.0001 0.051 0.009
(assumes 2 piles installed
simultaneously, 9 piling
events * 30 minutes each
event in a 24-hr period).
--------------------------------------------------------------------------------------------------------------------------------------------------------
* SPLs were calculated by decibel addition as presented in Table 6 using the largest pile size (42-in steel piles) and possible combinations of two and
three multiple hammer events. Please note: smaller piles may also have multiple hammer events; however, their SPLs would be smaller than the 42-in
steel pipe pile scenarios so they are not presented here. The HRCP will be using the largest Level A isopleths calculated regardless of pile size
during multiple hammering events.
For multiple hammering of 42-in steel pipe piles with a vibratory
hammer on a single day, the calculated Level A harassment isopleth for
the functional hearing groups would remain smaller than 100 m except
for high-frequency cetaceans (i.e., harbor porpoise). The Level A
harassment isopleth for harbor porpoises would be 132.5 m and 127.8 m
for the two scenarios (Table 11). It is unlikely that a harbor porpoise
could accumulate enough sound from the installation of multiple piles
in multiple locations for the duration required to meet these Level A
harassment thresholds. Additionally, other combinations of pile sizes
under multiple hammering with a vibratory hammer would result in Level
A harassment thresholds smaller than 100 m. To be precautionary, a
shutdown zone of 100 m would be implemented for all species for each
vibratory hammer on days when it is anticipated that multiple vibratory
hammers will be used regardless of pile size.
Level B Harassment
Utilizing the practical spreading loss model, underwater noise will
fall below the behavioral effects threshold of 120 and 160 dB rms for
marine mammals at the distances shown in Table 12 for vibratory and
impact pile driving, respectively. Table 12 below provides all Level B
harassment radial distances (m) and their corresponding areas (km\2\)
during HRCP's planned activities.
[[Page 48169]]
Table 12--Radial Distances (meters) to Relevant Behavioral Isopleths and Associated Ensonified Areas (km\2\)
Using the Practical Spreading Model
----------------------------------------------------------------------------------------------------------------
Distance to
level B Level B
Location and component Method and pile type harassment harassment
zone (m) zone (km\2\)
----------------------------------------------------------------------------------------------------------------
Vibratory Hammer (Level B Isopleth = 120 dB)
North Trestle
----------------------------------------------------------------------------------------------------------------
Moorings...................................... 42-in steel piles............... 15,849 96.781
North Shore Work Trestle...................... 36-in steel piles............... 13,594 85.525
Moorings...................................... 24-in steel piles............... 5,412 25.335
----------------------------------------------------------------------------------------------------------------
North Island
----------------------------------------------------------------------------------------------------------------
Moorings...................................... 42-in steel piles............... 15,849 100.937
----------------------------------------------------------------------------------------------------------------
South Island
----------------------------------------------------------------------------------------------------------------
TBM Platform.................................. 36-in steel piles............... 13,594 81.799
Conveyor Trestle.............................. 36-in steel piles............... 13,594 81.799
Jet Grouting Trestle.......................... 36-in steel piles............... 13,594 81.799
----------------------------------------------------------------------------------------------------------------
South Trestle
----------------------------------------------------------------------------------------------------------------
Moorings...................................... 42-in steel piles............... 15,849 305.343
Moorings...................................... 24-in steel piles............... 5,412 55.874
----------------------------------------------------------------------------------------------------------------
Willoughby Bay
----------------------------------------------------------------------------------------------------------------
Moorings...................................... 42-in steel piles............... 15,849 5.517
Moorings...................................... 24-in steel piles............... 5,412 5.517
----------------------------------------------------------------------------------------------------------------
Down-the-Hole Hammer (Level B Isopleth = 120 dB)
----------------------------------------------------------------------------------------------------------------
North Shore Work Trestle...................... 36-in steel piles............... 11,659 427.044
TBM Platform.................................. 36-in steel piles............... 11,659 427.044
Jet Grouting Trestle.......................... 36-in steel piles............... 11,659 427.044
Conveyor Trestle.............................. 36-in steel piles............... 11,659 427.044
----------------------------------------------------------------------------------------------------------------
Impact Hammer (Level B Isopleth = 160 dB)
North Trestle
----------------------------------------------------------------------------------------------------------------
North Shore Work Trestle...................... 36-in steel piles............... 1,585 3.806
----------------------------------------------------------------------------------------------------------------
South Island
----------------------------------------------------------------------------------------------------------------
TBM Platform.................................. 36-in steel piles............... 1,585 0.087
Conveyor Trestle.............................. 36-in steel piles............... 1,585 0.087
Jet Grouting Trestle with Bubble Curtain...... 36-in steel piles............... * 541 * 0.012
----------------------------------------------------------------------------------------------------------------
North Trestle, South Trestle, Willoughby Bay
----------------------------------------------------------------------------------------------------------------
Test Pile Program............................. 54-in concrete cylinder piles... 631 1.2509
Test Pile Program............................. 30-in concrete square piles..... 631 1.2509
Test Pile Program............................. 24-in concrete square piles..... 117 0.04
----------------------------------------------------------------------------------------------------------------
dB = decibels; km\2\ = square kilometers; TBM = Tunnel Boring Machine.
* Values smaller than other 36-in steel piles due to usage of a bubble curtain, resulting in a 7 dB reduction in
dB rms, dB peak, and dB SEL.
For the test pile program, in some cases, the calculated Level A
harassment isopleths are larger than the Level B harassment zones. This
has occurred due to the conservative assumptions going into calculation
of the Level A harassment isopleths. Animals will most likely respond
behaviorally before they are injured, especially at greater distances
and unlikely to accumulate noise levels over a certain period of time
that would likely lead to PTS.
When multiple vibratory hammers are used simultaneously, the
calculated Level B harassment zones (Table 13) would be larger than the
Level B harassment zones reported in above in Table 12 depending on the
combination of sound sources due to decibel addition of multiple
vibratory hammers as discussed earlier (see Table 7). Table 13 shows
the calculated distances to the Level B harassment zone for decibel
levels resulting from the simultaneous installation of piles with
multiple vibratory hammers using the data provided in Table 7. However,
the actual monitoring zones applied during multiple vibratory hammer
use are discussed in the Monitoring and Reporting section.
[[Page 48170]]
Table 13--Calculated Distances to Level B Harassment Zones for Multiple
Hammer Additions
------------------------------------------------------------------------
Distance to
level B
Combined SSL (dB) harassment
zone (m)
------------------------------------------------------------------------
163..................................................... 7,356
164..................................................... 8,577
165..................................................... 10,000
166..................................................... 11,659
167..................................................... 13,594
168..................................................... 15,849
169..................................................... 18,478
170..................................................... 21,544
171..................................................... 25,119
172..................................................... 29,286
173..................................................... 34,145
------------------------------------------------------------------------
Note: dB = decibels; SSL = sound source level.
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. Potential exposures to impact and vibratory pile driving
and removal for each acoustic threshold were estimated using local
observational data. Authorized take by Level A and B harassment is also
described.
Humpback Whales
Humpback whales are more rare in the project area and density data
for this species within the project vicinity are not available.
Humpback whale sighting data collected by the U.S. Navy near Naval
Station Norfolk and Virginia Beach from 2012 to 2015 (Engelhaupt et al.
2014, 2015, 2016) and in the mid-Atlantic (including the Chesapeake
Bay) from 2015 to 2018 (Aschettino et al. 2015, 2016, 2017a, 2018) did
not produce large enough sample sizes to calculate densities, or survey
data were not collected during systematic line-transect surveys.
Humpback whale densities have been calculated for populations off the
coast of New Jersey, resulting in a density estimate of 0.000130
animals per square kilometer or one humpback whale within the area on
any given day of the year (Whitt et al., 2015), which may be similar to
the density of whales in the project area. Aschettino et al. (2018)
observed and tracked two individual humpback whales in the Hampton
Roads area of the project area (Movebank, 2019). The HRCP is estimating
up to two whales may be exposed to project-related noise every two
months. Pile installation/removal is expected to occur over a 12-month
period; therefore, a total of 12 instances of take by Level B
harassment of humpback whales is authorized. Due to the low occurrence
of humpback whales and because large whales are easier to sight from a
distance, we do not anticipate or propose take of humpback whales by
Level A harassment.
Bottlenose Dolphin
The expected number of bottlenose dolphins in the project area was
estimated using inshore seasonal densities provided in Engelhaupt et
al. (2016) from vessel line-transect surveys near Naval Station Norfolk
and adjacent areas near Virginia Beach, Virginia, from August 2012
through August 2015 (Engelhaupt et al., 2016). NMFS used the density of
1.38 dolphins/km\2\ and (1) the Level B harassment ensonified area of
131.4 km\2\ west of the HRBT multiplied by 312 days of activities, plus
(2) the Level B harassment ensonified area of 221.46 km\2\ for
vibratory installation of 42-in steel piles at the South Trestle
multiplied by 7 days of activities, plus (3) the Level B harassment
ensonified area associated of 27.65 km\2\ for vibratory installation of
24-in steel piles at the South Trestle multiplied by 3 days of
activities, and plus (4) the Level B harassment ensonified area
associated of 0.87 km\2\ for impact installation of 54-in concrete
piles at the South Trestle multiplied 22 days of activities to increase
the numbers of Level B harassment takes of bottlenose dolphins from
6,343 to 58,856. (Table 14).
Table 14--Authorized Bottlenose Dolphin Take
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
24-in 54-in 42-in
Level B piles: piles: piles:
harassment Dolphin Days 24-in level B Dolphin Days 54-in level B Dolphin Days 42-in level B Dolphin
Total project days west of the density pile harassment density pile harassment density pile harassment density
HRBT (km2) (animals/ driving at South (animals/ driving at South (animals/ driving at South (animals/
km2) Trestle km2) Trestle km2) Trestle km2)
(km2) (km2) (km2)
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
312.............................................. 131.4 1.38 3 27.65 1.38 22 0.87 1.38 7 221.46 1.38
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
56,575.584 114.471
26.4132
2,139.3036
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Total Authorized Takes of Bottlenose Dolphin 58,855.77 (rounded to 58,856).
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Source: Engelhaupt et al., 2016.
Because the Level A harassment zones are relatively small (a 55-m
isopleth is the largest during DTH drilling of 36-in piles) and we
believe the PSO will be able to effectively monitor the Level A
harassment zones, we do not anticipate take by Level A harassment of
bottlenose dolphins.
Harbor Seals
The expected number of harbor seals in the project area was
estimated using systematic, land- and vessel-based survey data for in-
water and hauled-out seals collected by the U.S. Navy at the Chesapeake
Bay Bridge Tunnel (CBBT) rock armor and portal islands from 2014
through 2019 (Jones et al., 2020). The average daily seal count from
the 2014 through 2019 field seasons ranged from 8 to 23 for an average
of 13.6 harbor seals across all the field seasons (Table 15).
Table 15--Harbor Seal Counts at Chesapeake Bay Bridge Tunnel
----------------------------------------------------------------------------------------------------------------
``In season'' Total seal Average daily Max daily
Field season survey days count seal count seal count
----------------------------------------------------------------------------------------------------------------
2014-2015....................................... 11 113 10 33
2015-2016....................................... 14 187 13 39
2016-2017....................................... 22 308 14 40
2017-2018....................................... 15 340 23 45
[[Page 48171]]
2018-2019....................................... 10 82 8 17
---------------------------------------------------------------
Average..................................... .............. .............. 13.6 34.8
----------------------------------------------------------------------------------------------------------------
Source: Jones et al., 2020.
NMFS estimated take using the average daily seal count over five
field seasons (2014-2019) (Jones et al., 2020). This average count is
13.6 seals (rounded up to 14 seals). Fourteen seals/day multiplied by
156 days (number of days of activities when the seals are present,
December to May) equals 2,184 takes. The takes by Level A harassment
were calculated from approximately 21 percent of the pile-driving days
during DTH drilling when the Level A harassment zone is fairly large
(821 m) for a total of 459 takes. Therefore, 1,725 takes by Level B
harassment and 459 takes by Level A harassment are being authorized for
this IHA.
Gray Seals
The expected number of gray seals in the project area was estimated
using systematic, land- and vessel-based survey data for in-water and
hauled out seals collected by the U.S. Navy at the CBBT rock armor and
portal islands from 2014 through 2018 (Rees et al., 2016; Jones et al.,
2018). Seasonal numbers of gray seals in the Chesapeake Bay waters in
the vicinity of the project area in previous years have been low (Table
16). Gray seals are not expected to be present in the Chesapeake Bay
during the months of June through October (Table 16 and Table 17).
Table 16--Summary of Historical Gray Seal Sightings by Month From 2014 to 2018
----------------------------------------------------------------------------------------------------------------
Number of individual gray seals
-----------------------------------------------------------------------------------------------------------------
Monthly
Month 2014 2015 2016 2017 2018 average
----------------------------------------------------------------------------------------------------------------
January........................... ........... 0 0 0 0 0
February.......................... ........... 1 1 0 1 0.8
March............................. ........... 0 0 0 0 0
April............................. ........... 0 0 0 0 0
May............................... ........... 0 0 0 0 0
-----------------------------------------------------------------
June.............................. Seals not expected to be present. 0
-----------------------------------------------------------------
July.............................. Seals not expected to be present. 0
-----------------------------------------------------------------
August............................ Seals not expected to be present. 0
-----------------------------------------------------------------
September......................... Seals not expected to be present. 0
-----------------------------------------------------------------
October........................... Seals not expected to be present. 0
-----------------------------------------------------------------
November.......................... 0 0 0 0 ........... 0
December.......................... 0 0 0 0 ........... 0
----------------------------------------------------------------------------------------------------------------
Source: Rees et al., 2016; Jones et al., 2018.
Table 17--Average Number of Individual Gray Seal Sightings Summarized by
Season
------------------------------------------------------------------------
Average
number of
Season individuals
per season
------------------------------------------------------------------------
Spring (March-May)...................................... 0
Summer (June-August).................................... 0
Fall (September-November)............................... 0
Winter (December-February).............................. 1
------------------------------------------------------------------------
Note: Data generated from Table 16.
Gray seals are expected to be very uncommon in the project area.
The historical data indicate that approximately one gray seal has been
seen per year. To be conservative, HRCP requests three instances of
take by Level B harassment of gray seals during each winter month
(December through February). Therefore, HRCP estimated and NMFS is
authorizing nine instances of take by Level B harassment of gray seals
(three gray seals per month multiple by three months = nine gray
seals). Because of the unlikely to low occurrence of gray seals in the
project area, we do not anticipate and are not authorizing take by
Level A harassment of gray seals.
[[Page 48172]]
Harbor Porpoise
Harbor porpoises are known to occur in the coastal waters near
Virginia Beach (Hayes et al. 2019), and although they have been
reported on rare occasions in the Chesapeake Bay, closer to Norfolk,
they are rarely seen in the project area. Density data for this species
within the Project vicinity do not exist or were not calculated because
sample sizes were too small to produce reliable estimates of density.
Harbor porpoise sighting data collected by the U.S. Navy near Naval
Station Norfolk and Virginia Beach from 2012 to 2015 (Engelhaupt et
al., 2014; 2015; 2016) did not produce enough sightings to calculate
densities. One group of two harbor porpoises was seen during spring
2015 (Engelhaupt et al., 2016). Based on this data, it estimated that
one group of two harbor porpoises could be exposed to project-related
in-water noise each month during the spring (March-May) for a total of
six instances of take by Level B harassment (i.e., one group of two
individuals per month multiplied by three months = six harbor
porpoises).
The largest calculated Level A harassment isopleth for high
frequency cetaceans (i.e., harbor porpoises) extends 1,827 m during DTH
drilling of 36-in steel pipe piles. Because harbor porpoises are
relatively difficult to observe, it is possible they may occur within
the calculated Level A harassment zone without detection. As such, HRCP
requested a small number of takes by Level A harassment for harbor
porpoises during the project. Therefore, we authorize a total of two
instances of take by Level A harassment, the number requested by HRCP.
Table 18 below summarizes the authorized take for all the species
described above as a percentage of stock abundance.
Table 18--Authorized Take by Level A and B Harassment and as a Percentage of Stock Abundance
----------------------------------------------------------------------------------------------------------------
Authorized Authorized
level A level B Total takes Percentage of
Species Stock harassment harassment authorization stock
takes takes
----------------------------------------------------------------------------------------------------------------
Humpback whale............... Gulf of Maine... 0 12 12 Less than 2
percent.
Harbor porpoise.............. Gulf of Maine/ 2 4 6 Less than 1
Bay of Fundy. percent.
Bottlenose dolphin........... WNA Coastal, 0 29,320 29,320 Less than 33. *
Northern
Migratory \a\.
WNA Coastal, 0 29,320 29,320 Less than 33. *
Southern
Migratory \a\.
NNCES \a\....... 0 216 216 26.25.
Harbor seal.................. Western North 459 1,725 2,184 Less than 1
Atlantic. percent.
Gray seal.................... Western North 0 9 9 Less than 1
Atlantic. percent.
----------------------------------------------------------------------------------------------------------------
\a\ Take estimates are weighted based on calculated percentages of population for each distinct stock, assuming
animals present would follow same probability of presence in project area.
* Assumes multiple repeated takes of same individuals from small portion of each stock as well as repeated takes
of Chesapeake Bay resident population (size unknown).
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 such
activity, and other means of effecting the least practicable impact on
such species or stock and its habitat, paying particular attention to
rookeries, mating grounds, and areas of similar significance, and on
the availability of such species or stock for taking for certain
subsistence uses (latter not applicable for this action). NMFS
regulations require applicants for incidental take authorizations to
include information about the availability and feasibility (economic
and technological) of equipment, methods, and manner of conducting such
activity or other means of effecting the least practicable adverse
impact upon the affected species or stocks and their habitat (50 CFR
216.104(a)(11)).
In evaluating how mitigation may or may not be appropriate to
ensure the least practicable adverse impact on species or stocks and
their habitat, as well as subsistence uses where applicable, 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
proposed), the likelihood of effective implementation (probability
implemented as proposed), 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.
The following mitigation measures are included in the IHA:
Timing Restrictions
HRCP would conduct work during daylight hours, and if poor
environmental conditions restrict full visibility of the shutdown zone,
pile installation must be delayed. However, work may extend into the
night as necessary under conditions where there is full visibility of
the shutdown zone or where stopping ongoing work would otherwise create
an unsafe work condition.
Shutdown Zone for In-Water Heavy Machinery Work
For in-water heavy machinery work other than pile driving, if a
marine mammal comes within 10 m of such operations, operations will
cease and vessels will reduce speed to the minimum level required to
maintain steerage and safe working conditions.
Shutdown Zones
For all pile driving activities, HRCP will establish shutdown zones
for a marine mammal (see Table 19 below). The purpose of a shutdown
zone is generally to define an area within which shutdown of the
activity would occur upon sighting of a marine mammal (or in
anticipation of an animal entering the defined area). HRCP will
maintain a minimum 10 m shutdown zone for all pile driving activities
where the
[[Page 48173]]
calculated PTS Isopleth is less than 10 m as described in Table 11.
If multiple vibratory hammering occurs, a shutdown zone of 100 m
will be implemented for all species for each vibratory hammer on days
when it is anticipated that multiple vibratory hammers will be used
regardless of pile size.
During DTH drilling, a shutdown zone of 100 m for harbor seals will
be implemented to reduce unnecessary shutdowns.
Table 19--Shutdown Zones
----------------------------------------------------------------------------------------------------------------
Level a harassment shutdown zone (m)
---------------------------------------------------------------
Pile type/activity Sound source Low- Mid- High-
level at 10 m frequency frequency frequency Phocid
cetaceans cetaceans cetaceans
----------------------------------------------------------------------------------------------------------------
Vibratory Pile Driving
----------------------------------------------------------------------------------------------------------------
24-in steel pile installation 161 dB SPL...... 15 10 21 10
(All Locations).
36-in steel pile installation 167 dB SPL...... 32 10 47 20
(All Locations).
36-in steel pile installation 167 dB SPL...... 28 10 41 17
(TMB Platform).
42-in steel pile installation 168 dB SPL...... 42 10 62 26
(All Locations).
----------------------------------------------------------------------------------------------------------------
Impact Pile for the Jet Grouting Trestle
----------------------------------------------------------------------------------------------------------------
36-in steel pile installation. 183 dB SEL/193 243 10 290 130
SPL.
36-in steel pile installation 176 dB SEL/186 83 10 99 45
(attenuated). SPL.
----------------------------------------------------------------------------------------------------------------
Impact Pile Driving North Trestle
----------------------------------------------------------------------------------------------------------------
36-in steel pile installation 183 dB SEL/193 243 10 290 130
(North Shore Work Trestle). SPL.
----------------------------------------------------------------------------------------------------------------
Impact Pile Driving for North Trestle, Willoughby Bay, and South Trestle Test Pile Program
----------------------------------------------------------------------------------------------------------------
24-in concrete square pile 166 dB SEL/190 121 10 144 65
installation/removal. SPL.
30-in concrete square pile 177 dB SEL/187 652 24 777 349
installation/removal. SPL.
54-in concrete square pile 177 dB SEL/187 652 24 777 349
installation/removal. SPL.
----------------------------------------------------------------------------------------------------------------
Impact Pile Driving for South Island
----------------------------------------------------------------------------------------------------------------
36-in steel pile installation 183 dB SEL/193 243 10 290 130
(TBM Platform). SPL.
36-in steel pile installation 183 dB SEL/193 243 10 290 130
(Conveyor Trestle). SPL.
----------------------------------------------------------------------------------------------------------------
DTH Drilling
----------------------------------------------------------------------------------------------------------------
36-in steel pile installation 164SEL/180 dB 1,171 42 1,395 100
(TBM Platform). SPL.
36-in steel pile installation 164 SEL/180 dB 1,534 55 1,827 100
(North Shore Work Trestle). SPL.
36-in steel pile installation 164 SEL/180 dB 1,534 55 1,827 100
(Jet Grouting Trestle). SPL.
36-in steel pile installation 164 SEL/180 dB 1,534 55 1,827 100
(Conveyor Trestle). SPL.
----------------------------------------------------------------------------------------------------------------
Multiple Hammers--Vibratory Pile Driving (if occurs) *
----------------------------------------------------------------------------------------------------------------
42-in steel pile installation 173 dB SPL...... 100 100 100 100
(assumes 3 piles installed
simultaneously, 6 piling
events * 30 minutes each
event in a 24-hr period).
42-in steel pile installation 171 dB SPL...... 100 100 100 100
(assumes 2 piles installed
simultaneously, 9 piling
events * 30 minutes each
event in a 24-hr period).
----------------------------------------------------------------------------------------------------------------
* These zones are applicable for any multiple hammer events of any pile size where sound fields overlap.
[[Page 48174]]
Bubble Curtain
HRCP will use an air bubble curtain system during impact pile
driving of 36-in steel pipe piles for the Jet Grouting Trestle. Bubble
curtains would meet the following requirements:
The bubble curtain must distribute air bubbles around 100 percent
of the piling perimeter for the full depth of the water column. The
lowest bubble ring must be in contact with the mudline and/or rock
bottom for the full circumference of the ring, and the weights attached
to the bottom ring will ensure 100 percent mudline and/or rock bottom
contact. No parts of the ring or other objects will prevent full
mudline and/or rock bottom contact. The bubble curtain must be operated
such that there is proper (equal) balancing of air flow to all
bubblers. HRCP would employ the bubble curtain during impact pile
driving in water depths greater than 6 m (20 ft) at the Jet Grouting
Trestle.
Soft Start
HRCP would use soft start techniques when impact pile driving. Soft
start requires contractors to provide an initial set of strikes at
reduced energy, followed by a 30-second waiting period, then two
subsequent reduced energy strike sets. A soft start would be
implemented at the start of each day's impact pile driving and at any
time following cessation of impact pile driving for a period of 30
minutes or longer.
Non-Authorized Take Prohibited
If a species enters or approaches the Level B harassment zone and
that species is either not authorized for take or its authorized takes
are met, pile driving and removal activities must shut down immediately
using delay and shutdown procedures. Activities must not resume until
the animal has been confirmed to have left the area or an observation
time period of 15 minutes has elapsed.
Based on our evaluation of the HRCP's planned measures, NMFS has
determined that the mitigation measures provide the means 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
action area. Effective reporting is critical both to compliance as well
as ensuring that the most value is obtained from the required
monitoring.
Monitoring and reporting requirements prescribed by NMFS should
contribute to improved understanding of one or more of the following:
[ssquf] Occurrence of marine mammal species or stocks in the area
in which take is anticipated (e.g., presence, abundance, distribution,
density);
[ssquf] 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);
[ssquf] Individual marine mammal responses (behavioral or
physiological) to acoustic stressors (acute, chronic, or cumulative),
other stressors, or cumulative impacts from multiple stressors;
[ssquf] How anticipated responses to stressors impact either: (1)
Long-term fitness and survival of individual marine mammals; or (2)
populations, species, or stocks;
[ssquf] Effects on marine mammal habitat (e.g., marine mammal prey
species, acoustic habitat, or other important physical components of
marine mammal habitat); and
[ssquf] Mitigation and monitoring effectiveness.
Pre-Activity Monitoring
Prior to the start of daily in-water construction activity, or
whenever a break in pile driving of 30 min or longer occurs, PSOs will
observe the shutdown and monitoring zones for a period of 30 min. The
shutdown zone will be cleared when a marine mammal has not been
observed within the zone for that 30-min period. If a marine mammal is
observed within the shutdown zone, pile driving activities will not
begin until the animal has left the shutdown zone or has not been
observed for 15 min. If the Level B harassment zone (i.e., the
monitoring zone) has been observed for 30 min and no marine mammals
(for which take has not been authorized) are present within the zone,
work can continue even if visibility becomes impaired within the
monitoring zone. When a marine mammal for which Level B harassment take
has been authorized is present in the monitoring zone, piling
activities may begin and Level B harassment take will be recorded.
Monitoring Zones
The HRCP will establish monitoring zones for Level B harassment as
presented in Table 12. The monitoring zones for this project are areas
where SPLs are equal to or exceed 120 dB rms (for vibratory pile
driving/removal and DTH drilling) or 160 dB rms (for impact pile
driving). These zones provide utility for monitoring conducted for
mitigation purposes (i.e., shutdown zone monitoring) by establishing
monitoring protocols for areas adjacent to the shutdown zones.
Monitoring of the Level B harassment zones enables observers to be
aware of and communicate the presence of marine mammals in the project
area, and thus prepare for potential shutdowns of activity. The HRCP
will also be gathering information to help better understand the
impacts of their planned activities on species and their behavioral
responses. If the entire Level B harassment zone is not visible, Level
B harassment takes will be extrapolated based upon the number of
observed takes and the percentage of the Level B harassment zone that
is not visible.
Multiple Hammer Level B Harassment Zones
Due to the likelihood of multiple active construction sites across
the project area, it is possible that multiple vibratory hammers with
overlapping sound fields may be in operation simultaneously during
certain times throughout the duration of the project. As described in
the Estimated Take section, the decibel addition of continuous noise
sources results in much larger zone sizes than a single vibratory
hammer. Decibel addition is not a consideration when sound fields do
not overlap. Willoughby Bay is largely surrounded by land, and sound
will be prevented from propagating to other project construction sites
(see Figure 1-1 and Figure 6-1 of the application). Therefore,
Willoughby Bay will be treated as an independent site with its own
sound isopleths and observer requirements when construction is taking
place within the bay. Willoughby Bay is relatively small
[[Page 48175]]
and will be monitored from the construction site by a single observer.
Additionally, the South Trestle is the only site where the sound
will propagate into Chesapeake Bay (see Figure 6-1 of the application).
Sound from other construction sites will not overlap with South Trestle
and will not propagate into Chesapeake Bay. Therefore, the South
Trestle also will be treated as an independent site with its own sound
isopleths and observer requirements when construction is taking place.
When the South Trestle site is active, an observer will be positioned
on land to view as much of the Level B harassment zone as possible. If
the entire Level B harassment zone is not visible, Level B harassment
takes will be extrapolated based upon the number of observed takes and
the percentage of the Level B harassment zone that is not visible.
If two or more vibratory hammers at the other three project sites
(North Trestle, North Shore, South Island) are installing piles, there
is potential for the sound fields to overlap when installation occurs
simultaneously. If two piles that are 36-in or larger in diameter are
simultaneously installed with vibratory hammers, the Level B Harassment
zone can extend up to a 25 km radius to the southwest (see Figure 6-1,
171 dB isopleth of the application). However, the Level B harassment
zones resulting from simultaneous use of multiple vibratory hammers are
truncated in nearly all directions by the mainland and islands, which
prevent propagation of sound beyond the confines of a core area (see
Figure 11-1 (area outlined in red) of the application). The largest
ensonified radii extend to the south into the James and Nansemond
rivers, areas where marine mammal abundance is anticipated to be low
and approaching zero. Therefore, HRCP will monitor a core area, called
the Core Monitoring Area, during times when two or more vibratory
hammers are simultaneously active at the other three project
construction sites (North Trestle, North Shore, South Island). The Core
Monitoring Area would encompass the area between the two bridge/
tunnels, with observers positioned at key areas to monitor the
geographic area between the bridges (see Figure 11-1 (area outlined in
red) of the application). Depending on placement, the observers will be
able to view west/southwest towards Batten Bay and the mouth of the
Nansemond River. Marine mammals transiting the area will be located and
identified as they move in and out of the Chesapeake Bay.
Visual Monitoring
Monitoring would be conducted 30 minutes before, during, and 30
minutes after all pile driving/removal activities. In addition, PSOs
will record all incidents of marine mammal occurrence, regardless of
distance from activity, and will document any behavioral reactions in
concert with distance from piles being driven/removed. Pile driving/
removal activities include the time to install, 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 30 minutes.
Monitoring will be conducted by PSOs from land. The number of PSOs
will vary from one or more, depending on the type of pile driving,
method of pile driving and size of pile, all of which determines the
size of the harassment zones. Monitoring locations will be selected to
provide an unobstructed view of all water within the shutdown zone and
as much of the Level B harassment zone as possible for pile driving
activities. Monitoring locations may vary based on construction
activity and location of piles or equipment. HRCP will station between
one and four PSOs at locations offering the best available views of the
Level A and Level B monitoring zones during in-water pile driving at
the North Trestle, North Island, South Trestle, and South Island. When
and where able, as determined by the PSO or Lead PSO when multiple
observers are required, Level A and Level B harassment zones may be
monitored for multiple pile driving locations by the same individual
PSO. HRCP will be required to station between one and two PSOs at
locations offering the best available views of the Level A and Level B
monitoring zones during in-water pile driving at Willoughby Bay. If any
entire Level B monitoring zone is not visible, pile driving activities
may continue, and the number of individual animals within the Level B
zone will be estimated and recorded. Estimated numbers of individuals
will be extrapolated by dividing the number of observed individuals by
the percentage of the monitoring zone that was visible.
In addition, PSOs will work in shifts lasting no longer than 4
hours with at least a 1-hour break between shifts, and will not perform
duties as a PSO for more than 12 hours in a 24[hyphen]hour period (to
reduce PSO fatigue).
Monitoring of pile driving will be conducted by qualified, NMFS-
approved PSOs, who will have no other assigned tasks during monitoring
periods. The HRCP will adhere to the following conditions when
selecting PSOs:
[ssquf] Independent PSOs will be used (i.e., not construction
personnel);
[ssquf] At least one PSO must have prior experience working as a
marine mammal observer during construction activities;
[ssquf] Other PSOs may substitute education (degree in biological
science or related field) or training for experience;
[ssquf] Where a team of three or more PSOs are required, a lead
observer or monitoring coordinator will be designated. The lead
observer must have prior experience working as a marine mammal observer
during construction; and
[ssquf] The HRCP will submit PSO curriculum vitaes for approval by
NMFS for all observers prior to monitoring.
The HRCP will ensure that the PSOs have the following additional
qualifications:
[ssquf] Visual acuity in both eyes (correction is permissible)
sufficient for discernment of moving targets at the water's surface
with ability to estimate target size and distance; use of binoculars
may be necessary to correctly identify the target;
[ssquf] Experience and ability to conduct field observations and
collect data according to assigned protocols;
[ssquf] Experience or training in the field identification of
marine mammals, including the identification of behaviors;
[ssquf] Sufficient training, orientation, or experience with the
construction operation to provide for personal safety during
observations;
[ssquf] Writing skills sufficient to prepare a report of
observations including but not limited to the number and species of
marine mammals observed; dates and times when in-water construction
activities were conducted; dates, times, and reason for implementation
of mitigation (or why mitigation was not implemented when required);
and marine mammal behavior;
[ssquf] Ability to communicate orally, by radio or in person, with
project personnel to provide real-time information on marine mammals
observed in the area as necessary; and
[ssquf] Sufficient training, orientation, or experience with the
construction operations to provide for personal safety during
observations.
Reporting of Injured or Dead Marine Mammals
In the event that personnel involved in the construction activities
discover an injured or dead marine mammal, HRCP will report the
incident to the
[[Page 48176]]
Office of Protected Resources (OPR), NMFS and to the Greater Atlantic
Region New England/Mid-Atlantic Regional Stranding Coordinator as soon
as feasible. If the death or injury was clearly caused by the specified
activity, the HRCP must immediately cease the specified activities
until NMFS is able to review the circumstances of the incident and
determine what, if any, additional measures are appropriate to ensure
compliance with the terms of the IHA. HRCP must not resume their
activities until notified by NMFS.
The report must include the following information:
[ssquf] Time, date, and location (latitude/longitude) of the first
discovery (and updated location information if known and applicable);
[ssquf] Species identification (if known) or description of the
animal(s) involved;
[ssquf] Condition of the animal(s) (including carcass condition if
the animal is dead);
[ssquf] Observed behaviors of the animal(s), if alive;
[ssquf] If available, photographs or video footage of the
animal(s); and
[ssquf] General circumstances under which the animal was
discovered.
Final Report
The HRCP will submit a draft report to NMFS no later than 90 days
following the end of construction activities or 60 days prior to the
issuance of any subsequent IHA for the project. PSO datasheets/raw
sightings data would be required to be submitted with the reports. The
HRCP will provide a final report within 30 days following resolution of
NMFS' comments on the draft report. Reports will contain, at minimum,
the following:
[ssquf] Dates and times (begin and end) of all marine mammal
monitoring;
[ssquf] Construction activities occurring during each daily
observation period, including how many and what type of piles were
driven or removed and by what method (i.e., impact or vibratory);
[ssquf] Weather parameters and water conditions during each
monitoring period (e.g., wind speed, percent cover, visibility, sea
state);
[ssquf] The number of marine mammals observed, by species, relative
to the pile location and if pile driving or removal was occurring at
time of sighting;
[ssquf] Age and sex class, if possible, of all marine mammals
observed;
[ssquf] PSO locations during marine mammal monitoring;
[ssquf] Distances and bearings of each marine mammal observed to
the pile being driven or removed for each sighting (if pile driving or
removal was occurring at time of sighting);
[ssquf] Description of any marine mammal behavior patterns during
observation, including direction of travel and estimated time spent
within the Level A and Level B harassment zones while the source was
active;
[ssquf] Number of individuals of each species (differentiated by
month as appropriate) detected within the monitoring zone, and
estimates of number of marine mammals taken, by species (a correction
factor may be applied to total take numbers, as appropriate);
[ssquf] Detailed information about any implementation of any
mitigation triggered (e.g., shutdowns and delays), a description of
specific actions that ensued, and resulting behavior of the animal, if
any;
[ssquf] Description of attempts to distinguish between the number
of individual animals taken and the number of incidences of take, such
as ability to track groups or individuals;
[ssquf] An extrapolation of the estimated takes by Level B
harassment based on the number of observed exposures within the Level B
harassment zone and the percentage of the Level B harassment zone that
was not visible; and
[ssquf] Submit all PSO datasheets and/or raw sighting data (in a
separate file from the Final Report referenced immediately above).
Negligible Impact Analysis and Determination
NMFS has defined negligible impact as an impact resulting from the
specified activity that cannot be reasonably expected to, and is not
reasonably likely to, adversely affect the species or stock through
effects on annual rates of recruitment or survival (50 CFR 216.103). A
negligible impact finding is based on the lack of likely adverse
effects on annual rates of recruitment or survival (i.e., population-
level effects). An estimate of the number of takes alone is not enough
information on which to base an impact determination. In addition to
considering estimates of the number of marine mammals that might be
``taken'' through harassment, NMFS considers other factors, such as the
likely nature of any responses (e.g., intensity, duration), the context
of any responses (e.g., critical reproductive time or location,
migration), as well as effects on habitat, and the likely effectiveness
of the mitigation. 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). Of note, is the significant increase of takes by
Level B harassment for bottlenose dolphins compared with what was
evaluated in the notice of proposed IHA. Despite the increase in take
numbers, our determination remains the same. There could be multiple
takes of individual animals but without any long-term adverse effects.
Take by Level B harassment of bottlenose dolphins will be minimized
through use of mitigation measures.
Pile driving activities associated with the planned HRCP project,
as outlined previously, have the potential to disturb or displace
marine mammals. The specified activities may result in take, in the
form of Level B harassment (behavioral disturbance) or Level A
harassment (auditory injury), incidental to underwater sounds generated
from pile driving. Potential takes could occur if individuals are
present in the ensonified zone when pile driving occurs. Level A
harassment is only anticipated and authorized for harbor porpoises and
harbor seals.
No serious injury or mortality is anticipated given the nature of
the activities and measures designed to minimize the possibility of
injury to marine mammals. The potential for these outcomes is minimized
through the construction method and the implementation of the
mitigation measures. When impact pile driving is used, implementation
of bubble curtains (during 36-in steel piles at the Jet Grouting
Trestle in water depths greater than 6 m (20 ft)), soft start and
shutdown zones significantly reduce the possibility of injury. Given
sufficient notice through use of soft starts (for impact driving),
marine mammals are expected to move away from a sound source that is
annoying prior to it becoming potentially injurious.
HRCP will use qualified PSOs stationed strategically to increase
detectability of marine mammals, enabling a high rate of success in
implementation of shutdowns to avoid injury for most species. PSOs will
be stationed to provide a relatively clear view of the shutdown zones
and monitoring zones. These factors will limit exposure of animals to
noise levels that could result in injury.
[[Page 48177]]
HRCP's planned pile driving activities are highly localized. Only a
relatively small portion of the Chesapeake Bay may be affected.
Localized noise exposures produced by project activities may cause
short-term behavioral modifications in affected cetaceans and
pinnipeds. Moreover, the mitigation and monitoring measures are
expected to further reduce the likelihood of injury as well as reduce
behavioral disturbances.
Effects on individuals that are taken by Level B harassment, on the
basis of reports in the literature as well as monitoring from other
similar activities, will likely be limited to reactions such as
increased swimming speeds, increased surfacing time, or decreased
foraging (if such activity were occurring) (e.g., Thorson and Reyff
2006). Individual animals, even if taken multiple times, will most
likely move away from the sound source and be temporarily displaced
from the areas of pile driving, although even this reaction has been
observed primarily only in association with impact pile driving. The
pile driving activities analyzed here are similar to, or less impactful
than, numerous other construction activities conducted along both
Atlantic and Pacific coasts, which have taken place with no known long-
term adverse consequences from behavioral harassment. Furthermore, many
projects similar to this one are also believed to result in multiple
takes of individual animals without any documented long-term adverse
effects. Level B harassment will be minimized through use of mitigation
measures described herein and, if sound produced by project activities
is sufficiently disturbing, animals are likely to simply avoid the area
while the activity is occurring.
In addition to the expected effects resulting from authorized Level
B harassment, we anticipate that small numbers of harbor porpoises and
some harbor seals may enter the Level A harassment zones undetected,
particularly during times of DTH drilling when the Level A harassment
zones are large. It is unlikely that the animals would remain in the
area long enough for PTS to occur. If any animals did experience PTS,
it would likely only receive slight PTS, i.e. minor degradation of
hearing capabilities within regions of hearing that align most
completely with the energy produced by pile driving (i.e., the low-
frequency region below 2 kHz), not severe hearing impairment or
impairment in the regions of greatest hearing sensitivity. If hearing
impairment occurs, it is most likely that the affected animal's
threshold would increase by a few dBs, which is not likely to
meaningfully affect its ability to forage and communicate with
conspecifics. As described above, we expect that marine mammals would
be likely to move away from a sound source that represents an aversive
stimulus, especially at levels that would be expected to result in PTS,
given sufficient notice through use of soft start.
The project is not expected to have significant adverse effects on
marine mammal habitat. No important feeding and/or reproductive areas
for marine mammals are known to be near the project area. Project
activities would not permanently modify existing marine mammal habitat.
The activities may cause some fish to leave the area of disturbance,
thus temporarily impacting marine mammal foraging opportunities in a
limited portion of the foraging range. However, because of the
relatively small area of the habitat that may be affected, the impacts
to marine mammal habitat are not expected to cause significant or long-
term negative consequences.
In summary and as described above, the following factors primarily
support our determination that the impacts resulting from this activity
are not expected to adversely affect the species or stock through
effects on annual rates of recruitment or survival:
No mortality is anticipated or authorized;
Limited Level A harassment exposures (harbor porpoises and
harbor seals) are anticipated;
The anticipated incidents of Level B harassment consist
of, at worst, temporary modifications in behavior that would not result
in fitness impacts to individuals;
The specified activity and associated ensonifed areas are
very small relative to the overall habitat ranges of all species and
does not include habitat areas of special significance (Biologically
Important Areas or ESA-designated critical habitat); and
The presumed efficacy of the mitigation measures in
reducing the effects of the specified activity.
Based on the analysis contained herein of the likely effects of the
specified activity on marine mammals and their habitat, and taking into
consideration the implementation of the monitoring and mitigation
measures, NMFS finds that the total marine mammal take from the
activity will have a negligible impact on all affected marine mammal
species or stocks.
Small Numbers
As noted above, only small numbers of incidental take may be
authorized under sections 101(a)(5)(A) and (D) of the MMPA for
specified activities other than military readiness activities. The MMPA
does not define small numbers and so, in practice, where estimated
numbers are available, NMFS compares the number of individuals taken to
the most appropriate estimation of abundance of the relevant species or
stock in our determination of whether an authorization is limited to
small numbers of marine mammals. Additionally, other qualitative
factors may be considered in the analysis, such as the temporal or
spatial scale of the activities.
The authorized take of four of the five marine mammal species/
stocks comprises less than one-third of the best available stock
abundance, with the exception of the bottlenose dolphin stocks. There
are three bottlenose dolphin stocks that could occur in the project
area. Therefore, the estimated dolphin takes by Level B harassment
would likely be portioned among the western North Atlantic northern
migratory coastal stock, western North Atlantic southern migratory
coastal stock, and NNCES stock. Based on the stocks' respective
occurrence in the area, NMFS estimated that there would be 216 takes
from the NNCES stock, with the remaining takes evenly split between the
northern and southern migratory coastal stocks. Based on consideration
of various factors described below, we have determined the numbers of
individuals taken would likely comprise less than one-third of the best
available population abundance estimate of either coastal migratory
stock.
Both the northern migratory coastal and southern migratory coastal
stocks have expansive ranges and they are the only dolphin stocks
thought to make broad-scale, seasonal migrations in coastal waters of
the western North Atlantic. Given the large ranges associated with
these two stocks it is unlikely that large segments of either stock
would approach the project area and enter into the Chesapeake Bay. The
majority of both stocks are likely to be found widely dispersed across
their respective habitat ranges and unlikely to be concentrated in or
near the Chesapeake Bay.
Furthermore, the Chesapeake Bay and nearby offshore waters
represent the boundaries of the ranges of each of the two coastal
stocks during migration. The northern migratory coastal stock is found
during warm water months from
[[Page 48178]]
coastal Virginia, including the Chesapeake Bay and Long Island, New
York. The stock migrates south in late summer and fall. During cold
water months dolphins may be found in coastal waters from Cape Lookout,
North Carolina, to the North Carolina/Virginia. During January-March,
the southern migratory coastal stock appears to move as far south as
northern Florida. From April to June, the stock moves back north to
North Carolina. During the warm water months of July-August, the stock
is presumed to occupy coastal waters north of Cape Lookout, North
Carolina, to Assateague, Virginia, including the Chesapeake Bay. There
is likely some overlap between the northern and southern migratory
stocks during spring and fall migrations, but the extent of overlap is
unknown.
The Chesapeake Bay and waters offshore of the mouth are located on
the periphery of the migratory ranges of both coastal stocks (although
during different seasons). Additionally, each of the migratory coastal
stocks are likely to be located in the vicinity of the Chesapeake Bay
for relatively short timeframes. Given the limited number of animals
from each migratory coastal stock likely to be found at the seasonal
migratory boundaries of their respective ranges, in combination with
the short time periods (~two months) animals might remain at these
boundaries, it is reasonable to assume that takes are likely to occur
only within some small portion of either of the migratory coastal
stocks.
Both migratory coastal stocks likely overlap with the NNCES stock
at various times during their seasonal migrations. The NNCES stock is
defined as animals that primarily occupy waters of the Pamlico Sound
estuarine system (which also includes Core, Roanoke, and Albemarle
sounds, and the Neuse River) during warm water months (July-August).
Members of this stock also use coastal waters (<=1 km from shore) of
North Carolina from Beaufort north to Virginia Beach, Virginia,
including the lower Chesapeake Bay. Comparison of dolphin photo-
identification data confirmed that limited numbers of individual
dolphins observed in Roanoke Sound have also been sighted in the
Chesapeake Bay (Young, 2018). Like the migratory coastal dolphin
stocks, the NNCES stock covers a large range. The spatial extent of
most small and resident bottlenose dolphin populations is on the order
of 500 km\2\, while the NNCES stock occupies over 8,000 km\2\
(LeBrecque et al., 2015). Given this large range, it is again unlikely
that a preponderance of animals from the NNCES stock would depart the
North Carolina estuarine system and travel to the northern extent of
the stock's range. However, recent evidence suggests that there is
likely a small resident community of NNCES dolphins of indeterminate
size that inhabits the Chesapeake Bay year-round (E. Patterson, NMFS,
pers. comm.).
Many of the dolphin observations in the Bay are likely repeated
sightings of the same individuals. The Potomac-Chesapeake Dolphin
Project has observed over 1,200 unique animals since observations began
in 2015. Re-sightings of the same individual can be highly variable.
Some dolphins are observed once per year, while others are highly
regular with greater than 10 sightings per year (J. Mann, Potomac-
Chesapeake Dolphin Project, pers. comm.). Similarly, using available
photo-identification data, Engelhaupt et al. (2016) determined that
specific individuals were often observed in close proximity to their
original sighting locations and were observed multiple times in the
same season or same year. Ninety-one percent of re-sighted individuals
(100 of 110) in the study area were recorded less than 30 km from the
initial sighting location. Multiple sightings of the same individual
would considerably reduce the number of individual animals that are
taken by Level B harassment. Furthermore, the existence of a resident
dolphin population in the Bay would increase the percentage of dolphin
takes that are actually re-sightings of the same individuals.
In summary and as described above, the following factors primarily
support our determination regarding the incidental take of small
numbers of the affected stocks of bottlenose dolphin:
Potential bottlenose dolphin takes in the project area are
likely to be allocated among three distinct stocks;
Bottlenose dolphin stocks in the project area have
extensive ranges and it would be unlikely to find a high percentage of
any one stock concentrated in a relatively small area such as the
project area or the Chesapeake Bay;
The Chesapeake Bay represents the migratory boundary for
each of the specified dolphin stocks and it would be unlikely to find a
high percentage of any stock concentrated at such boundaries; and
Many of the takes would likely be repeats of the same
animals and likely from a resident population of the Chesapeake Bay.
Based on the analysis contained herein of the planned activity
(including the mitigation and monitoring measures) and the anticipated
take of marine mammals, NMFS finds that small numbers of marine mammals
will be taken relative to the population size of the affected species
or stocks.
Unmitigable Adverse Impact Analysis and Determination
There are no relevant subsistence uses of the affected marine
mammal stocks or species implicated by this action. Therefore, NMFS has
determined that the total taking of affected species or stocks would
not have an unmitigable adverse impact on the availability of such
species or stocks for taking for subsistence purposes.
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 evaluate our proposed action (i.e., the promulgation of
regulations and subsequent issuance of incidental take authorization)
and alternatives with respect to potential impacts on the human
environment. This action is consistent with categories of activities
identified in Categorical Exclusion B4 of the Companion Manual for NAO
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 determined that
the action qualified 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. No incidental take of ESA-listed marine mammals are
expected or authorized. Therefore, NMFS determined that consultation
under section 7 of the ESA was not required for this action.
Authorization
As a result of these determinations, NMFS has issued an IHA to the
HRCP for pile driving activities associated with the HRBT Expansion
Project in Hampton-Norfolk, Virginia for a period of one year provided
the previously mentioned mitigation, monitoring, and reporting
requirements are incorporated.
[[Page 48179]]
Dated: August 4, 2020.
Donna S. Wieting,
Director, Office of Protected Resources, National Marine Fisheries
Service.
[FR Doc. 2020-17344 Filed 8-7-20; 8:45 am]
BILLING CODE 3510-22-P