[Federal Register Volume 85, Number 55 (Friday, March 20, 2020)]
[Notices]
[Pages 16194-16226]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2020-05807]
[[Page 16193]]
Vol. 85
Friday,
No. 55
March 20, 2020
Part II
Department of Commerce
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National Oceanic and Atmospheric Administration
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Take of Marine Mammals Incidental to Specified Activities; Taking
Marine Mammals Incidental to the Hampton Roads Bridge-Tunnel Expansion
Project, Hampton-Norfolk, Virginia; Notice
Federal Register / Vol. 85 , No. 55 / Friday, March 20, 2020 /
Notices
[[Page 16194]]
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DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
[RTID 0648-XA053]
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; proposed incidental harassment authorization; request
for comments on proposed authorization and possible renewals.
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SUMMARY: NMFS has received a request from the Hampton Roads Connector
Partners (HRCP) for an authorization to take marine mammals incidental
to the pile driving activities associated with the Hampton Roads
Bridge-Tunnel (HRBT) Expansion Project. Pursuant to the Marine Mammal
Protection Act (MMPA), NMFS is requesting comments on its proposal to
issue an incidental harassment authorization (IHA) to incidentally take
marine mammals during the specified activities. NMFS is also requesting
comments on a possible one-year renewal that could be issued under
certain circumstances and if all requirements are met, as described in
Request for Public Comments at the end of this notice. NMFS will
consider public comments prior to making any final decision on the
issuance of the requested MMPA authorization and agency responses will
be summarized in the final notice of our decision.
DATES: Comments and information must be received no later than April
20, 2020.
ADDRESSES: Comments should be addressed to Jolie Harrison, Chief,
Permits and Conservation Division, Office of Protected Resources,
National Marine Fisheries Service. Physical comments should be sent to
1315 East-West Highway, Silver Spring, MD 20910 and electronic comments
should be sent to [email protected].
Instructions: NMFS is not responsible for comments sent by any
other method, to any other address or individual, or received after the
end of the comment period. Comments received electronically, including
all attachments, must not exceed a 25-megabyte file size. Attachments
to electronic comments will be accepted in Microsoft Word or Excel or
Adobe PDF file formats only. All comments received are a part of the
public record and will generally be posted online at https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act without change. All personal identifying
information (e.g., name, address) voluntarily submitted by the
commenter may be publicly accessible. Do not submit confidential
business information or otherwise sensitive or protected information.
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.
National Environmental Policy Act
To comply with the National Environmental Policy Act of 1969 (NEPA;
42 U.S.C. 4321 et seq.) and NOAA Administrative Order (NAO) 216-6A,
NMFS must review our proposed action (i.e., the issuance of an
incidental harassment authorization) with respect to potential impacts
on the human environment.
These actions are consistent with categories of activities
identified in Categorical Exclusion B4 (incidental harassment
authorizations with no anticipated serious injury or mortality) of the
Companion Manual for NOAA Administrative Order 216-6A, which do not
individually or cumulatively have the potential for significant impacts
on the quality of the human environment and for which we have not
identified any extraordinary circumstances that would preclude this
categorical exclusion. Accordingly, NMFS has preliminarily determined
that the issuance of the proposed IHA qualifies to be categorically
excluded from further NEPA review.
We will review all comments submitted in response to this notice
prior to concluding our NEPA process or making a final decision on the
IHA request.
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 proposed 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 Proposed 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
[[Page 16195]]
overall project will widen I-64 for approximately 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 proposed activities below
are part of the overall project (see the applicant for additional
details on the overall project). Only the activities relevelant to the
Incidental Harassment Authorization (IHA) requested by HRCP are
discussed below. This includes the following components:
TBM Platform at the South Island;
Conveyor Trestle at the South Island;
Temporary trestles for jet grouting at the South Island;
Temporary trestle for bridge construction at the North
Shore;
Mooring piles at the South Trestle (located at the South
Island), North Island, and Willoughby Bay; and
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. During
jetting, high-pressure water is sprayed out of the bottom of the pile
to help penetrate dense sand layers and to allow pile driving with
lower hammer impact energies (Caltrans 2015). The pressurized fluid
would be used to temporary loosen soils thus reducing the resistance of
the pile to sinking into the ground. Jetting woul be conducted at the
surface of the seabed but rather at depth once sufficient resistance to
pile driving has been met. Jetting would not be used to remove or
displace surface sediments. The caisson will be driven using a
vibratory hammer and the sediment and sand removed from the caisson
prior to driving the permanent concrete pile. Vibratory hammering is
accounted for takes of marine mammals.
Dates and Duration
The IHA application is requesting take that may occur from the pile
driving and removal activities for one year after issuance. Work could
occur at any point during the year, and will occur during the day. Pile
installation may extend into 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. 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 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.
[[Page 16196]]
[GRAPHIC] [TIFF OMITTED] TN20MR20.000
The North Shore in Hampton contains estuarine intertidal sandy
shore, estuarine intertidal reef, as well as submerged aquatic
vegetation (SAV) in shallow estuarine open water. Along the North
Trestle, there is estuarine open water with depths up to 15 feet below
mean lower low water (MLLW).
The North Island is surrounded by estuarine intertidal sandy shore
and rocky shore. There is a SAV bed to the east of the island.
Estuarine open water depths are primarily less than 15 feet (ft) below
MLLW, but drop to approximately 25 feet below MLLW near the southwest
corner of the island expansion closer to the Hampton Creek Entrance
Channel. The South Island is also surrounded by estuarine intertidal
sandy shore and rocky shore, followed by estuarine open water. The
proposed island expansion is mainly in deep water (15-30 ft below
MLLW), with a pocket of deeper water approximately 35 ft below MLLW to
the west.
The South Trestle is primarily located in estuarine open water with
depths less than 15 ft below MLLW, with the exception of deep water
(15-30 ft below MLLW) near the South Island approach. There is an
estuarine intertidal sandy shore along the South Shore in Norfolk.
Willoughby Bay contains an estuarine intertidal sandy shore, with
emergent and scrub/shrub wetlands along the shores. The bay between the
shores is estuarine open water with depths up to 15 ft below MLLW.
Sediments in the project area are mostly fine and medium sands with
various amounts of coarse sand and gravel, and low organic carbon
content. In the Fort Wool Cove (a cove of the decommissioned island
fortification located approximately 1 mile south of Fort Monroe in the
mouth of Hampton Roads, which sits near Willoughby Beach and Willoughby
Spit, adjacent to the HRBT), sediments are fine and very fine sands
with various amounts of silt and clay. There is no naturally occurring
rocky or cobble bottom present at or adjacent to the project.
Pile installation will occur in waters ranging in depth from less
than 1 meter (m) (3.3 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
[[Page 16197]]
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 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.
A down-the-hole hammer uses both rotary and percussion-type drill
devices. This device consists of a drill bit that drills through rock
using both rotary and pulse impact mechanisms. This breaks up the rock
to allow removal of the fragments and insertion of the pile. The pile
is usually advanced at the same time that drilling occurs. Drill
cuttings are expelled from the top of the pile using compressed air. 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 0.6 mile 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 1.8 miles 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 1.2 miles 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 0.6 mile 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 1.0 mile 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 1.0 mile 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 1.5 miles 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 1.2 miles along I-64.
BILLING CODE 3510-22-P
[[Page 16198]]
[GRAPHIC] [TIFF OMITTED] TN20MR20.001
BILLING CODE 3510-22-C
However, the only the proposed 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:
North Trestle-Bridges (Segment 1b);
Tunnel--North Island and South Island (Segment 2a);
South Trestle-Bridge (Segment 3a); and
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
[[Page 16199]]
be delivered by barge and then transferred to the platform using a
Self- 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 166 ft x 9 ft). 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 154 ft long and will have an
average embedded length of approximately 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[hyphen]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.
Four mooring dolphins will be installed along the shoreline of the
South Island in the areas adjacent to the TBM Platform. Each dolphin
will consist of three 36-inch 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 673 ft x 27 ft). 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 140 ft long and will have an average embedded length of
approximately 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, seven mooring dolphins will be installed along the
outside edge of the Conveyor Trestle. Each dolphin will consist of (3)
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 (< 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 30-40 ft
spans sized to accommodate a 300-ton crane. The main portion of the
work trestle will be approximately 1,130 ft long by 45 ft wide, with
three approximately 80 ft x 30 ft fingers and an additional landing
area approximately 150 ft x 45 ft, for a total overall approximate area
of 1.49 acres.
Seven mooring dolphins will be installed at the southern end and
along the outside edge of the work trestle. Each dolphin will consist
of (3) 24-in steel piles. An additional (13) 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 proposed 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 proposed tunnel alignment and tunnel depth.
Two temporary work trestles will be constructed along either side
of the proposed tunnel alignment to support jet grouting activity. Each
trestle will be approximately 40 ft wide and extend approximately 1,000
ft west of the South Island shoreline, for a total overall approximate
area of 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 25 +/- feet 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
[[Page 16200]]
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
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 concrete pile design during April through June 2020. 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
Number of down- the- Number of Average Approximate Number of Estimated
Pile size/type and Total Embedment piles hole piles vibratory number of piles per total Number of
Project component material number of length down- the- duration vibrated/ duration impact day per number of days of
piles (feet) hole per pile hammered per pile strikes hammer hours of installation
(minutes) (minutes) per pile installation
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North Trestle (Segment 1b)
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North Shore Work Trestle............... 36-inch Steel Pipe....... 194 100 10 120 184 50 40 3 162 65
Moorings............................... 42-inch Steel Pipe....... 36 60 .......... .......... 36 30 ........... 6 18 6
Moorings............................... 24-inch Steel Pipe....... 30 60 .......... .......... 30 30 ........... 6 15 5
Test Pile Program (Load Test Piles).... 54-inch Concrete Cylinder 1 140 .......... .......... 1 .......... 2,100 1 2 1
Pipe.
Test Pile Program (Production Piles)... 54-inch Concrete Cylinder 10 140 .......... .......... 10 .......... 2,100 1 20 10
Pipe.
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North Island (Segment 2a)
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Moorings............................... 42-inch Steel Pipe....... 80 60 .......... .......... 80 30 ........... 6 40 13
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Willoughby Bay (Segment 3c)
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Moorings............................... 42-inch Steel Pipe....... 50 60 .......... .......... 50 30 ........... 6 25 9
Moorings............................... 24-inch Steel Pipe....... 18 60 .......... .......... 18 30 ........... 6 9 3
Moorings (Safe Haven).................. 42-inch Steel Pipe....... 50 60 .......... .......... 50 30 ........... 6 25 9
Test Pile Program (Load Test Piles).... 24-inch or 30-inch 1 140 .......... .......... 1 .......... 2,100 1 2 1
Concrete Square Pipe.
Test Pile Program (Production Piles)... 24-inch or 30-inch 15 140 .......... .......... 15 .......... 2,100 1 30 15
Concrete Square Pipe.
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
South Trestle (Segment 3a)
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Moorings............................... 42-inch Steel Pipe....... 41 60 .......... .......... 41 30 ........... 6 21 7
Moorings............................... 24-inch Steel Pipe....... 18 60 .......... .......... 18 30 ........... 6 9 3
Test Pile Program (Load Test Piles).... 54-inch Concrete Cylinder 2 140 .......... .......... 2 .......... 2,100 1 4 2
Pipe.
Test Pile Program (Production Piles)... 54-inch, Concrete 20 140 .......... .......... 20 .......... 2,100 1 40 20
Cylinder Pipe.
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
South Island (Segment 2a)
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
TBM Platform........................... 36-inch Steel Pipe....... 216 140 108 120 108 60 60 2 216 108
Jet Grouting Trestle................... 36-inch Steel Pipe....... 204 100 20 120 184 50 40 3 170 68
Conveyor Trestle....................... 36-inch Steel Pipe....... 84 100 8 120 76 50 40 3 70 28
--------------------------------------------------------------------------------------------------------------------------------------------------------
Total.............................. ......................... 1,070 ........... .......... .......... .......... .......... ........... .......... ............ ............
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Proposed 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):
North Trestle-Bridges (Segment 1b);
Tunnel--North Island and South Island (Segment 2a);
South Trestle-Bridge (Segment 3a); and
Willoughby Bay Trestle-Bridges (Segment 3c).
Proposed mitigation, monitoring, and reporting measures are
described in detail later in this document (please see Proposed
Mitigation and Monitoring and Reporting section).
Description of Marine Mammals in the Area of Specified Activities
Sections 3 and 4 of the application summarize available information
regarding status and trends, distribution and habitat preferences, and
behavior and life history, of the potentially affected species.
Additional information regarding population trends and threats may be
found in NMFS's Stock Assessment Reports (SARs; https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments) and more general information about these species
(e.g., physical and behavioral descriptions) may be found on NMFS's
website (https://www.fisheries.noaa.gov/find-species).
Table 2 lists all species or stocks for which take is expected and
proposed to be 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
[[Page 16201]]
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 Stock
Assessments (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
--------------------------------------------------------------------------------------------------------------------------------------------------------
ESA/ MMPA status; Stock abundance (CV,
Common name Scientific name Stock Strategic (Y/N) Nmin, most recent PBR Annual M/
\1\ abundance survey) \2\ SI \3\
--------------------------------------------------------------------------------------------------------------------------------------------------------
Order Cetartiodactyla--Cetacea--Superfamily 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........... WNA Coastal, Northern -,-; Y 6,639 (0.41; 4,759; 48 6.1-13.2
Migratory. 2011).
....................... WNA Coastal, Southern -,-; Y 3,751 (0.06; 2,353; 23 0-14.3
Migratory. 2011).
....................... Northern North Carolina -,-; Y 823 (0.06; 782; 2013). 7.8 0.8-18.2
Estuarine System.
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 we have proposed
authorizing it. All species that could potentially occur in the
proposed 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 beyond the
explanation provided here.
Based on sighting data and passive acoustic studies, the North
Atlantic right whale could occur off Virginia year-round (DoN 2009;
Salisbury et al., 2016). They have also been reported seasonally off
Virginia during migrations in the spring, fall, and winter (CeTAP 1981,
1982; Niemeyer et al., 2008; Kahn et al., 2009; McLellan 2011b, 2013;
Mallette et al., 2016a, b, 2017, 2018a; Palka et al., 2017; Cotter
2019). Right whales are known to frequent the coastal waters of the
mouth of the Chesapeake Bay (Knowlton et al., 2002) and the area is a
seasonal management area (1 November-30 April) mandating reduced ship
speeds out to approximately 20 nautical miles for the species; however,
the project area is further inside the bay.
North Atlantic right whales have stranded in Virginia, one each in
2001, 2002, 2004, 2005: Three during winter (February and March) and
one in summer (September) (Costidis et al., 2017, 2019). In January
2018, a dead, entangled North Atlantic right whale was observed
floating over 60 miles offshore of Virginia Beach (Costidis et al.,
2019). All North Atlantic right whale strandings in Virginia waters
have occurred on ocean-facing beaches along Virginia Beach and the
barrier islands seaward of the lower Delmarva Peninsula (Costidis et
al., 2017).
Due to the low occurrence of North Atlantic right whales in the
project area,
[[Page 16202]]
NMFS is not proposing to authorize take of this species.
Fin whales have been sighted off Virginia (Cetacean and Turtle
Assessment Program (CeTAP) 1981, 1982; Swingle et al., 1993; DoN 2009;
Hyrenbach et al., 2012; Barco 2013; Mallette et al., 2016a, b;
Aschettino et al., 2018; Engelhaupt et al., 2017, 2018; Cotter 2019),
and in the Chesapeake Bay (Bailey 1948; CeTAP 1981, 1982; Morgan et
al., 2002; Barco 2013; Aschettino et al., 2018); however, they are not
likely to occur in the project area. Sightings have been documented
around the Chesapeake Bay Bridge Tunnel (CBBT) during the winter months
(CeTAP 1981, 1982; Barco 2013; Aschettino et al., 2018).
Eleven fin whale strandings have occurred off Virginia from 1988 to
2016 mostly during the winter months of February and March, followed by
a few in the spring and summer months (Costidis et al., 2017). Six of
the strandings occurred in the Chesapeake Bay (three on eastern shore;
three on western shore) with the remaining five occurring on the
Atlantic coast (Costidis et al., 2017. Documented strandings near the
project area have occurred: February 2012, a dead fin whale washed
ashore on Oceanview Beach in Norfolk (Swingle et al., 2013); December
2017, a live fin whale stranded on a shoal in Newport News and died at
the site (Swingle et al., 2018); February 2014, a dead fin whale
stranded on a sand bar in Pocomoke Sound near Great Fox Island,
Accomack (Swingle et al., 2015); and, March 2007, a dead fin whale near
Craney Island, in the Elizabeth River, in Norfolk (Barco 2013).
Only stranded fin whales have been documented in the project area;
no free-swimming fin whales have been observed. Due to the low
occurrence of fin whales in the project area, NMFS is not proposing to
authorize take of this species.
Minke whales have been sighted off Virginia (CeTAP 1981, 1982;
Hyrenbach et al. 2012; Barco 2013; Mallette et al., 2016a, b; McLellan
2017; Engelhaupt et al., 2017, 2018; Cotter 2019), near the CBBT
(Aschettino et al., 2018) and in the project area although the
sightings in the project area are known from strandings (Jensen and
Silber 2004; Barco 2013; DoN 2009). In August 1994, a ship strike
incident involved a minke whale in Hampton Roads (Jensen and Silber
2004; Barco 2013). It was reported that the animal was struck offshore
and was carried inshore on the bow of a ship (DoN 2009). Twelve
strandings of minke whales have occurred in Virginia waters from 1988
to 2016 (Costidis et al., 2017). There have been six minke whale
stranding from 2017 through 2020 in Virginia waters.
Because all minke whale occurrences in the project area are due to
strandings, NMFS is not proposing to authorize take of this species.
Cetaceans
Humpback Whale
The humpback whale is found worldwide in all oceans. Humpbacks
occur off southern New England in all four seasons, with peak abundance
in spring and summer. In winter, humpback whales from waters off New
England, Canada, Greenland, Iceland, and Norway migrate to mate and
calve primarily in the West Indies (including the Antilles, the
Dominican Republic, the Virgin Islands and Puerto Rico), where spatial
and genetic mixing among these groups occurs.
Migrating humpback whales utilize the mid-Atlantic as a migration
pathway between calving/mating grounds to the south and feeding grounds
in the north (Hayes et al. 2019), but it may also be an important
winter feeding area for juveniles. Since 1989, observations of juvenile
humpbacks in the mid-Atlantic have been increasing during the winter
months, peaking from January through March (Swingle et al., 1993).
Biologists theorize that non-reproductive animals may be establishing a
winter feeding range in the mid-Atlantic since they are not
participating in reproductive behavior in the Caribbean. Swingle et al.
(1993) identified a shift in distribution of juvenile humpback whales
in the nearshore waters of Virginia, primarily in winter months.
Identified whales using the mid-Atlantic area were found to be
residents of the Gulf of Maine and Atlantic Canada (Gulf of St.
Lawrence and Newfoundland) feeding groups; suggesting a mixing of
different feeding populations in the Mid-Atlantic region.
Humpback whales are the only large cetaceans that are likely to
occur in the project area and could be found there at any time of the
year. The project area is not within normal humpback whale feeding or
migration areas; however, they could occur in the Project area in
relatively small numbers seasonally during migrations (Aschettino et
al., 2017b). Sightings have been reported off Virginia during the fall
and winter (CeTAP 1981, 1982; Swingle et al., 1993; Barco et al., 2002;
McLellan 2011a; Engelhaupt et al., 2014, 2015, 2016, 2017, 2018;
Aschettino et al., 2015, 2016, 2017a, 2018, 2019; Mallette et al.,
2016a, b, 2017, 2018a, b; McAlarney et al., 2017, 2018; Northeast
Fisheries Science Center and Southeast Fisheries Science Center (NEFSC
and SEFSC) 2019) and most recently, the spring (Aschettino et al.,
2019; Cotter, 2019). Humpback whales are known to frequent the coastal
waters of the mouth of the Chesapeake Bay during the winter months
(Aschettino et al,. 2015, 2016, 2017a, b, 2018; Movebank, 2019), and on
the rare occasion, inshore of the CBBT (Perkins and Beamish, 1979;
Aschettino et al., 2017b, 2018; Movebank, 2019). Humpback whales could
use the Chesapeake Bay area year-round based off sighting and stranding
data (DoN, 2009; Aschettino et al., 2015, 2016, 2017a, 2018, 2019).
Baseline occurrence and behavior data for humpback whales in the
Hampton Roads mid-Atlantic region was collected via satellite tags;
these data show site fidelity to the Chesapeake Bay area (Aschettino et
al., 2018, 2019) and movement in and around the project area (Movebank,
2019).
Vessel collisions and entanglements can cause serious injuries to
humpback whales. Thirty-seven humpback whale strandings have occurred
in Virginia from 1988 to 2016 (Costidis et al., 2017). Humpback whale
strandings or entanglements have been recorded in every month of the
year with April having the highest number of strandings (Costidis et
al., 2017). Twenty-seven of the 37 strandings occurred on ocean-facing
beaches; however, some have occurred within the lower Chesapeake Bay
(Barco, 2013; Costidis et al., 2017). Since January 2016, elevated
humpback whale mortalities have occurred along the Atlantic coast from
Maine through Florida. The event has been declared a UME with 117
strandings recorded of which 23 strandings occurred in the waters of
Virginia and seven of which occurred in or near the mouth of the
Chesapeake Bay. Partial or full necropsy examinations have been
conducted on approximately half of the known cases. A portion of the
whales have shown evidence of pre-mortem vessel strike; however, this
finding is not consistent across all of the whales examined so more
research is needed. NOAA is consulting with researchers that are
conducting studies on the humpback whale populations, and these efforts
may provide information on changes in whale distribution and habitat
use that could provide additional insight into how these vessel
interactions occurred. More detailed information is available at:
https://www.fisheries.noaa.gov/national/marine-life-distress/2016-2019-humpback-whale-unusual-mortality-event-along-atlantic-coast. Three
previous UMEs involving humpback whales have occurred since 2000, in
2003, 2005, and 2006.
[[Page 16203]]
Bottlenose Dolphin
The bottlenose dolphin occurs in temperate and tropical oceans
throughout the world, ranging in latitudes from 45[deg] N to 45[deg] S
(Blaylock, 1985). In the western Atlantic Ocean there are two distinct
morphotypes of bottlenose dolphins, an offshore type that occurs along
the edge of the continental shelf as well as an inshore type. The
inshore morphotype can be found along the entire United States coast
from New York to the Gulf of Mexico, and typically occurs in waters
less than 20 m deep (NOAA Fisheries, 2016a). Bottlenose dolphins found
in Virginia are representative primarily of either the northern
migratory coastal stock, southern migratory coastal stock, or the
Northern North Carolina Estuarine System Stock (NNCES).
The northern migratory coastal stock is best defined by its
distribution during warm water months when the stock occupies coastal
waters from the shoreline to approximately the 20-m isobath between
Assateague, Virginia, and Long Island, New York (Garrison et al.,
2017b). The stock migrates in late summer and fall and, during cold
water months (best described by January and February), occupies coastal
waters from approximately Cape Lookout, North Carolina, to the North
Carolina/Virginia border (Garrison et al., 2017b). Historically, common
bottlenose dolphins have been rarely observed during cold water months
in coastal waters north of the North Carolina/Virginia border, and
their northern distribution in winter appears to be limited by water
temperatures. Overlap with the southern migratory coastal stock in
coastal waters of northern North Carolina and Virginia is possible
during spring and fall migratory periods, but the degree of overlap is
unknown and it may vary depending on annual water temperature (Garrison
et al., 2016). When the stock has migrated in cold water months to
coastal waters from just north of Cape Hatteras, North Carolina, to
just south of Cape Lookout, North Carolina, it overlaps spatially with
the Northern North Carolina Estuarine System (NNCES) Stock (Garrison et
al., 2017b).
The southern migratory coastal stock migrates seasonally along the
coast between North Carolina and northern Florida (Garrison et al.,
2017b). During January-March, the southern migratory coastal stock
appears to move as far south as northern Florida. During April-June,
the stock moves back north past Cape Hatteras, North Carolina (Garrison
et al., 2017b), where it overlaps, in coastal waters, with the NNCES
stock (in waters <=1 km from shore). 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.
The NNCES stock is best defined as animals that occupy primarily
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. A community of
NNCES dolphins are likely year-round Bay residents (E. Patterson, NMFS
pers. comm).
Bottlenose dolphins are consistently seen in Virginia waters from
May through October (Barco et al., 1999; Costidis et al., 2017; Cotter,
2019) and are regularly sighted from early spring through late fall
with sightings and stranding events in Virginia waters all months of
the year (Swingle et al., 2010, 2011, 2012, 2013, 2014; DolphinWatch
2019). Sightings have been reported off Virginia and near the project
area during the summer, fall, and winter (CeTAP,, 1981, 1982; Hohn
1997; Torres et al., 2005; NEFSC and SEFSC 2012, 2013, 2016; Barco
2013, 2014; Garrison 2013; DiMatteo 2014; Roberts et al., 2016;
Engelhaupt et al., 2014, 2015, 2016, 2017, 2018; Palka et al., 2017;
Mallette et al., 2016a, b, 2017, 2018a, b; McAlarney et al., 2017,
2018; DolphinWatch 2019).
Harbor Porpoise
The harbor porpoise is typically found in colder waters in the
northern hemisphere. In the western North Atlantic Ocean, harbor
porpoises range from Greenland to as far south as North Carolina (Barco
and Swingle, 2014). They are commonly found in bays, estuaries, and
harbors less than 200 meters deep (NOAA Fisheries, 2017c). Harbor
porpoises in the United States are made up of the Gulf of Maine/Bay of
Fundy stock. Gulf of Maine/Bay of Fundy stock are concentrated in the
Gulf of Maine in the summer, but are widely dispersed from Maine to New
Jersey in the winter. South of New Jersey, harbor porpoises occur at
lower densities. Migrations to and from the Gulf of Maine do not follow
a defined route (NOAA Fisheries, 2016c).
The inland waters of Virginia are considered to be part of the
normal habitat of the harbor porpoise (Polacheck et al., 1995; DoN
2009). Sightings have been reported off Virginia (DoN 2009; Hyrenbach
et al., 2012) and they regularly occur in the Chesapeake Bay (Prescott
and Fiorelli 1980; Polacheck et al., 1995; DoN 2009). A few sightings
have occurred near the HRBT (M. Cotter, HDR Inc., pers. comm. May 2019
as cited in the application). There are documented sightings near the
project area during the spring and winter, although, most of these
sightings are known from stranding data (Polacheck et al., 1995; Cox et
al., 1998; Morgan et al., 2002; Swingle et al., 2007; Barco 2013).
Pinnipeds
Harbor Seal
The harbor seal occurs in arctic and temperate coastal waters
throughout the northern hemisphere, including on both the east and west
coasts of the United States. On the east coast, harbor seals can be
found from the Canadian Arctic down to Georgia (Blaylock, 1985). Harbor
seals occur year-round in Canada and Maine and seasonally (September-
May) from southern New England to New Jersey (NOAA Fisheries, 2016d).
The range of harbor seals appears to be shifting as they are regularly
reported further south than they were historically. In recent years,
they have established haulout sites in the Chesapeake Bay including on
the portal islands of the Chesapeake Bay Bridge Tunnel (CBBT) (Rees et
al., 2016, Jones et al., 2018).
Harbor seals are the most common seal in Virginia (Barco and
Swingle, 2014). Harbor seal presence in Virginia waters is seasonal,
with individuals arriving in January and February (winter) and
extending into April and May (spring) (Costidis et al., 2017). They can
be seen resting on the rocks around the portal islands of the CBBT from
December through April. Seal observation surveys conducted at the CBBT
recorded 112 seals during the 2014/2015 season, 184 seals during the
2015/2016 season, 308 seals in the 2016/2017 season and 340 seals
during the 2017/2018 season. Smaller numbers of harbor seals have been
known to occasionally haul out on the rocks near the HRBT (Danielle
Jones, Naval Facilities Engineering Command Atlantic, pers. comm.,
April 2019 as cited in the application) and at Hopewell up the James
River (Blaylock 1985; DoN 2009). Sightings have been reported off
Virginia and near the project area during the winter and spring (Barco,
2013; Rees et al., 2016; Jones et al., 2018; Ampela et al., 2019).
Gray Seal
The gray seal occurs on both coasts of the Northern Atlantic Ocean
and is
[[Page 16204]]
divided into three major populations (NOAA Fisheries, 2016b). The
western north Atlantic stock occurs in eastern Canada and the
northeastern United States, occasionally as far south as North
Carolina. Gray seals inhabit rocky coasts and islands, sandbars, ice
shelves and icebergs (NOAA Fisheries, 2016b). In the United States,
gray seals congregate in the summer to give birth at four established
colonies in Massachusetts and Maine (NOAA Fisheries, 2016b). From
September through May, they disperse and can be abundant as far south
as New Jersey. The range of gray seals appears to be shifting as they
are regularly being reported further south than they were historically
(Rees et al., 2016).
Gray seals are uncommon in Virginia and the Chesapeake Bay. Only 15
gray seal strandings were documented in Virginia from 1988 through 2013
(Barco and Swingle, 2014). They are rarely found resting on the rocks
around the portal islands of the CBBT from December through April
alongside harbor seals. Seal observation surveys conducted at the CBBT
recorded one gray seal in each of the 2014/2015 and 2015/2016 seasons
while no gray seals were reported during the 2016/2017 and 2017/2018
seasons (Rees et al., 2016, Jones et al., 2018). Sightings have been
reported off Virginia and near the project area during the winter and
spring (Barco 2013; Rees et al., 2016; Jones et al., 2018; Ampela et
al., 2019).
Marine Mammal Habitat
No ESA-designated critical habitat overlaps with the project area.
A migratory Biologically Important Area (BIA) for North Atlantic right
whales is found offshore of the mouth of the Chesapeake Bay but does
not overlap with the project area. As previously described, right
whales are rarely observed in the Bay and sound from the proposed in-
water activities are not anticipated to propagate outside of the Bay to
the area associated with the BIA.
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 divided
into functional hearing groups based on directly measured or estimated
hearing ranges on the basis of available behavioral response data,
audiograms derived using auditory evoked potential techniques,
anatomical modeling, and other data. Note that no direct measurements
of hearing ability have been successfully completed for mysticetes
(i.e., low-frequency cetaceans). Subsequently, NMFS (2018) described
generalized hearing ranges for these marine mammal hearing groups.
Generalized hearing ranges were chosen based on the approximately 65
decibel (dB) threshold from the normalized composite audiograms, with
the exception for lower limits for low-frequency cetaceans where the
lower bound was deemed to be biologically implausible and the lower
bound from Southall et al. (2007) retained. Marine mammal hearing
groups and their associated hearing ranges are provided in Table 3.
Table 3--Marine Mammal Hearing Groups
[NMFS, 2018]
------------------------------------------------------------------------
Hearing group Generalized hearing range *
------------------------------------------------------------------------
Low-frequency (LF) cetaceans (baleen 7 Hz to 35 kHz.
whales).
Mid-frequency (MF) cetaceans (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 (3 cetacean and 2 phocid pinniped) have the
reasonable potential to co-occur with the proposed 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
This section includes a summary and discussion of the ways that
components of the specified activity may impact marine mammals and
their habitat. The Estimated Take by Incidental Harassment section
later in this document includes a quantitative analysis of the number
of individuals that are expected to be taken by this activity. The
Negligible Impact Analysis and Determination section considers the
content of this section, the Estimated Take by Incidental Harassment
section, and the Proposed Mitigation section, to draw conclusions
regarding the likely impacts of these activities on the reproductive
success or survivorship of individuals and how those impacts on
individuals are likely to impact marine mammal species or stocks.
Description of Sound Sources
The marine soundscape is comprised of both ambient and
anthropogenic sounds. Ambient sound is defined as the all-encompassing
sound in a given place and is usually a composite of sound from many
sources both near and far. The sound level of an area is defined by the
total acoustical energy being generated by known and unknown sources.
These sources may include physical (e.g., waves, wind, precipitation,
earthquakes, ice, atmospheric sound), biological (e.g., sounds produced
by marine mammals, fish, and invertebrates), and
[[Page 16205]]
anthropogenic sound (e.g., vessels, dredging, aircraft, construction).
The sum of the various natural and anthropogenic sound sources at
any given location and time--which comprise ``ambient'' or
``background'' sound--depends not only on the source levels (as
determined by current weather conditions and levels of biological and
shipping activity) but also on the ability of sound to propagate
through the environment. In turn, sound propagation is dependent on the
spatially and temporally varying properties of the water column and sea
floor, and is frequency-dependent. As a result of the dependence on a
large number of varying factors, ambient sound levels can be expected
to vary widely over both coarse and fine spatial and temporal scales.
Sound levels at a given frequency and location can vary by 10-20 dB
from day to day (Richardson et al. 1995). The result is that, depending
on the source type and its intensity, sound from the specified activity
may be a negligible addition to the local environment or could form a
distinctive signal that may affect marine mammals.
In-water construction activities associated with the project would
include impact pile driving, vibratory pile driving, vibratory pile
removal, and drilling with a DTH hammer. The sounds produced by these
activities fall into one of two general sound types: Impulsive and non-
impulsive. Impulsive sounds (e.g., explosions, gunshots, sonic booms,
impact pile driving) are typically transient, brief (less than 1
second), broadband, and consist of high peak sound pressure with rapid
rise time and rapid decay (ANSI 1986; NIOSH 1998; NMFS 2018). Non-
impulsive sounds (e.g. aircraft, machinery operations such as drilling
or dredging, vibratory pile driving, and active sonar systems) can be
broadband, narrowband or tonal, brief or prolonged (continuous or
intermittent), and typically do not have the high peak sound pressure
with raid rise/decay time that impulsive sounds do (ANSI 1995; NIOSH
1998; NMFS 2018). The distinction between these two sound types is
important because they have differing potential to cause physical
effects, particularly with regard to hearing (e.g., Ward 1997 in
Southall et al. 2007).
Impact hammers operate by repeatedly dropping a heavy piston onto a
pile to drive the pile into the substrate. Sound generated by impact
hammers is characterized by rapid rise times and high peak levels, a
potentially injurious combination (Hastings and Popper 2005). Vibratory
hammers install piles by vibrating them and allowing the weight of the
hammer to push them into the sediment. Vibratory hammers produce
significantly less sound than impact hammers. Peak sound pressure
levels (SPLs) may be 180 dB or greater, but are generally 10 to 20 dB
lower than SPLs generated during impact pile driving of the same-sized
pile (Oestman et al., 2009). Rise time is slower, reducing the
probability and severity of injury, and sound energy is distributed
over a greater amount of time (Nedwell and Edwards, 2002; Carlson et
al., 2005). A DTH hammer is used to place hollow steel piles or casings
by drilling. A DTH hammer is a drill bit that drills through the
bedrock using a pulse mechanism that functions at the bottom of the
hole. This pulsing bit breaks up rock to allow removal of debris and
insertion of the pile. The head extends so that the drilling takes
place below the pile. The pulsing sounds produced by DTH hammers were
previously thought to be continuous. However, the Chesapeake Tunnel
Joint Venture (CTJV) conducted sound source verification (SSV)
monitoring and the most significant finding was that the DTH hammer
created an impulsive sound as the equipment was employed at the
Parallel Thimble Shoal Tunnel Project in Virginia Beach, Virginia
(Denes et al. 2019).
The likely or possible impacts of HRCP's proposed activity on
marine mammals could involve both non-acoustic and acoustic stressors.
Potential non-acoustic stressors could result from the physical
presence of the equipment and personnel; however, any impacts to marine
mammals are expected to primarily be acoustic in nature. Acoustic
stressors include effects of heavy equipment operation during pile
installation.
Acoustic Impacts
The introduction of anthropogenic noise into the aquatic
environment from pile driving is the primary means by which marine
mammals may be harassed from CTJV's specified activity. In general,
animals exposed to natural or anthropogenic sound may experience
physical and psychological effects, ranging in magnitude from none to
severe (Southall et al. 2007). Exposure to in-water construction noise
has the potential to result in auditory threshold shifts and behavioral
reactions (e.g., avoidance, temporary cessation of foraging and
vocalizing, changes in dive behavior) and/or lead to non-observable
physiological responses such an increase in stress hormones
((Richardson et al. 1995; Gordon et al. 2004; Nowacek et al. 2007;
Southall et al. 2007; Gotz et al. 2009). Additional noise in a marine
mammal's habitat can mask acoustic cues used by marine mammals to carry
out daily functions such as communication and predator and prey
detection. The effects of pile driving noise on marine mammals are
dependent on several factors, including, but not limited to, sound type
(e.g., impulsive vs. non-impulsive), the species, age and sex class
(e.g., adult male vs. mom with calf), duration of exposure, the
distance between the pile and the animal, received levels, behavior at
time of exposure, and previous history with exposure (Wartzok et al.
2004; Southall et al. 2007). Here we discuss physical auditory effects
(threshold shifts), followed by behavioral effects and potential
impacts on habitat.
Richardson et al. (1995) described zones of increasing intensity of
effect that might be expected to occur, in relation to distance from a
source and assuming that the signal is within an animal's hearing
range. First is the area within which the acoustic signal would be
audible (potentially perceived) to the animal, but not strong enough to
elicit any overt behavioral or physiological response. The next zone
corresponds with the area where the signal is audible to the animal and
of sufficient intensity to elicit behavioral or physiological
responsiveness. Third is a zone within which, for signals of high
intensity, the received level is sufficient to potentially cause
discomfort or tissue damage to auditory or other systems. Overlaying
these zones to a certain extent is the area within which masking (i.e.,
when a sound interferes with or masks the ability of an animal to
detect a signal of interest that is above the absolute hearing
threshold) may occur; the masking zone may be highly variable in size.
We describe the more severe effects (i.e., permanent hearing
impairment, certain non-auditory physical or physiological effects)
only briefly as we do not expect that there is a reasonable likelihood
that HRCP's activities would result in such effects (see below for
further discussion). NMFS defines a noise-induced threshold shift (TS)
as a change, usually an increase, in the threshold of audibility at a
specified frequency or portion of an individual's hearing range above a
previously established reference level (NMFS 2018). The amount of
threshold shift is customarily expressed in dB. A TS can be permanent
or temporary. As described in NMFS (2018), there are numerous factors
to consider when examining the consequence of TS, including, but not
limited to, the signal
[[Page 16206]]
temporal pattern (e.g., impulsive or non-impulsive), likelihood an
individual would be exposed for a long enough duration or to a high
enough level to induce a TS, the magnitude of the TS, time to recovery
(seconds to minutes or hours to days), the frequency range of the
exposure (i.e., spectral content), the hearing and vocalization
frequency range of the exposed species relative to the signal's
frequency spectrum (i.e., how animal uses sound within the frequency
band of the signal; e.g., Kastelein et al. 2014b), and the overlap
between the animal and the source (e.g., spatial, temporal, and
spectral).
Permanent Threshold Shift (PTS)--NMFS defines PTS as a permanent,
irreversible increase in the threshold of audibility at a specified
frequency or portion of an individual's hearing range above a
previously established reference level (NMFS 2018). Available data from
humans and other terrestrial mammals indicate that a 40 dB threshold
shift approximates PTS onset (see Ward et al., 1958, 1959; Ward, 1960;
Kryter et al., 1966; Miller, 1974; Ahroon et al., 1996; Henderson et
al., 2008). PTS levels for marine mammals are estimates, as with the
exception of a single study unintentionally inducing PTS in a harbor
seal (Kastak et al., 2008), there are no empirical data measuring PTS
in marine mammals largely due to the fact that, for various ethical
reasons, experiments involving anthropogenic noise exposure at levels
inducing PTS are not typically pursued or authorized (NMFS, 2018).
Temporary Threshold Shift (TTS)--A temporary, reversible increase
in the threshold of audibility at a specified frequency or portion of
an individual's hearing range above a previously established reference
level (NMFS 2018). Based on data from cetacean TTS measurements (see
Southall et al., 2007), a TTS of 6 dB is considered the minimum
threshold shift clearly larger than any day-to-day or session-to-
session variation in a subject's normal hearing ability (Schlundt et
al., 2000; Finneran et al., 2000, 2002). As described in Finneran
(2016), marine mammal studies have shown the amount of TTS increases
with cumulative sound exposure level (SELcum) in an accelerating
fashion: At low exposures with lower SELcum, the amount of TTS is
typically small and the growth curves have shallow slopes. At exposures
with higher SELcum, the growth curves become steeper and approach
linear relationships with the noise SEL.
Depending on the degree (elevation of threshold in dB), duration
(i.e., recovery time), and frequency range of TTS, and the context in
which it is experienced, TTS can have effects on marine mammals ranging
from discountable to serious (similar to those discussed in auditory
masking, below). For example, a marine mammal may be able to readily
compensate for a brief, relatively small amount of TTS in a non-
critical frequency range that takes place during a time when the animal
is traveling through the open ocean, where ambient noise is lower and
there are not as many competing sounds present. Alternatively, a larger
amount and longer duration of TTS sustained during time when
communication is critical for successful mother/calf interactions could
have more serious impacts. We note that reduced hearing sensitivity as
a simple function of aging has been observed in marine mammals, as well
as humans and other taxa (Southall et al., 2007), so we can infer that
strategies exist for coping with this condition to some degree, though
likely not without cost.
Currently, TTS data only exist for four species of cetaceans
(bottlenose dolphin, beluga whale (Delphinapterus leucas), harbor
porpoise, and Yangtze finless porpoise (Neophocoena asiaeorientalis))
and five species of pinnipeds exposed to a limited number of sound
sources (i.e., mostly tones and octave-band noise) in laboratory
settings (Finneran, 2015). TTS was not observed in trained spotted
(Phoca largha) and ringed (Pusa hispida) seals exposed to impulsive
noise at levels matching previous predictions of TTS onset (Reichmuth
et al., 2016). In general, harbor seals and harbor porpoises have a
lower TTS onset than other measured pinniped or cetacean species
(Finneran, 2015). Additionally, the existing marine mammal TTS data
come from a limited number of individuals within these species. No data
are available on noise-induced hearing loss for mysticetes. For
summaries of data on TTS in marine mammals or for further discussion of
TTS onset thresholds, please see Southall et al., (2007), Finneran and
Jenkins (2012), Finneran (2015), and Table 5 in NMFS (2018).
Behavioral Harassment--Behavioral disturbance may include a variety
of effects, including subtle changes in behavior (e.g., minor or brief
avoidance of an area or changes in vocalizations), more conspicuous
changes in similar behavioral activities, and more sustained and/or
potentially severe reactions, such as displacement from or abandonment
of high-quality habitat. Disturbance may result in changing durations
of surfacing and dives, number of blows per surfacing, or moving
direction and/or speed; reduced/increased vocal activities; changing/
cessation of certain behavioral activities (such as socializing or
feeding); visible startle response or aggressive behavior (such as
tail/fluke slapping or jaw clapping); avoidance of areas where sound
sources are located. Pinnipeds may increase their haul out time,
possibly to avoid in-water disturbance (Thorson and Reyff, 2006).
Behavioral responses to sound are highly variable and context-specific
and any reactions depend on numerous intrinsic and extrinsic factors
(e.g., species, state of maturity, experience, current activity,
reproductive state, auditory sensitivity, time of day), as well as the
interplay between factors (e.g., Richardson et al. 1995; Wartzok et
al., 2003; Southall et al., 2007; Weilgart 2007; Archer et al., 2010).
Behavioral reactions can vary not only among individuals but also
within an individual, depending on previous experience with a sound
source, context, and numerous other factors (Ellison et al., 2012), and
can vary depending on characteristics associated with the sound source
(e.g., whether it is moving or stationary, number of sources, distance
from the source). In general, pinnipeds seem more tolerant of, or at
least habituate more quickly to, potentially disturbing underwater
sound than do cetaceans, and generally seem to be less responsive to
exposure to industrial sound than most cetaceans. Please see Appendices
B-C of Southall et al. (2007) for a review of studies involving marine
mammal behavioral responses to sound.
Habituation can occur when an animal's response to a stimulus wanes
with repeated exposure, usually in the absence of unpleasant associated
events (Wartzok et al., 2003). Animals are most likely to habituate to
sounds that are predictable and unvarying. It is important to note that
habituation is appropriately considered as a ``progressive reduction in
response to stimuli that are perceived as neither aversive nor
beneficial,'' rather than as, more generally, moderation in response to
human disturbance (Bejder et al., 2009). The opposite process is
sensitization, when an unpleasant experience leads to subsequent
responses, often in the form of avoidance, at a lower level of
exposure.
As noted above, behavioral state may affect the type of response.
For example, animals that are resting may show greater behavioral
change in response to disturbing sound levels than animals that are
highly motivated to remain in an area for feeding (Richardson et al.,
1995; NRC, 2003; Wartzok et al., 2003). Controlled experiments with
captive
[[Page 16207]]
marine mammals have showed pronounced behavioral reactions, including
avoidance of loud sound sources (Ridgway et al., 1997; Finneran et al.,
2003). Observed responses of wild marine mammals to loud pulsed sound
sources (typically seismic airguns or acoustic harassment devices) have
been varied but often consist of avoidance behavior or other behavioral
changes suggesting discomfort (Morton and Symonds 2002; see also
Richardson et al., 1995; Nowacek et al., 2007).
Available studies show wide variation in response to underwater
sound; therefore, it is difficult to predict specifically how any given
sound in a particular instance might affect marine mammals perceiving
the signal. If a marine mammal does react briefly to an underwater
sound by changing its behavior or moving a small distance, the impacts
of the change are unlikely to be significant to the individual, let
alone the stock or population. However, if a sound source displaces
marine mammals from an important feeding or breeding area for a
prolonged period, impacts on individuals and populations could be
significant (e.g., Lusseau and Bejder 2007; Weilgart 2007; NRC 2005).
However, there are broad categories of potential response, which we
describe in greater detail here, that include alteration of dive
behavior, alteration of foraging behavior, effects to breathing,
interference with or alteration of vocalization, avoidance, and flight.
Changes in dive behavior can vary widely, and may consist of
increased or decreased dive times and surface intervals as well as
changes in the rates of ascent and descent during a dive (e.g., Frankel
and Clark 2000; Costa et al., 2003; Ng and Leung 2003; Nowacek et al.,
2004; Goldbogen et al. 2013a,b). Variations in dive behavior may
reflect interruptions in biologically significant activities (e.g.,
foraging) or they may be of little biological significance. The impact
of an alteration to dive behavior resulting from an acoustic exposure
depends on what the animal is doing at the time of the exposure and the
type and magnitude of the response.
Disruption of feeding behavior can be difficult to correlate with
anthropogenic sound exposure, so it is usually inferred by observed
displacement from known foraging areas, the appearance of secondary
indicators (e.g., bubble nets or sediment plumes), or changes in dive
behavior. As for other types of behavioral response, the frequency,
duration, and temporal pattern of signal presentation, as well as
differences in species sensitivity, are likely contributing factors to
differences in response in any given circumstance (e.g., Croll et al.,
2001; Nowacek et al., 2004; Madsen et al., 2006; Yazvenko et al.,
2007). A determination of whether foraging disruptions incur fitness
consequences would require information on or estimates of the energetic
requirements of the affected individuals and the relationship between
prey availability, foraging effort and success, and the life history
stage of the animal.
Variations in respiration naturally vary with different behaviors
and alterations to breathing rate as a function of acoustic exposure
can be expected to co-occur with other behavioral reactions, such as a
flight response or an alteration in diving. However, respiration rates
in and of themselves may be representative of annoyance or an acute
stress response. Various studies have shown that respiration rates may
either be unaffected or could increase, depending on the species and
signal characteristics, again highlighting the importance in
understanding species differences in the tolerance of underwater noise
when determining the potential for impacts resulting from anthropogenic
sound exposure (e.g., Kastelein et al., 2001; 2005b, 2006; Gailey et
al. 2007).
Marine mammals vocalize for different purposes and across multiple
modes, such as whistling, echolocation click production, calling, and
singing. Changes in vocalization behavior in response to anthropogenic
noise can occur for any of these modes and may result from a need to
compete with an increase in background noise or may reflect increased
vigilance or a startle response. For example, in the presence of
potentially masking signals, humpback whales and killer whales have
been observed to increase the length of their songs (Miller et al.,
2000; Fristrup et al., 2003; Foote et al., 2004), while right whales
have been observed to shift the frequency content of their calls upward
while reducing the rate of calling in areas of increased anthropogenic
noise (Parks et al., 2007b). In some cases, animals may cease sound
production during production of aversive signals (Bowles et al., 1994).
Avoidance is the displacement of an individual from an area or
migration path as a result of the presence of a sound or other
stressors, and is one of the most obvious manifestations of disturbance
in marine mammals (Richardson et al., 1995). For example, gray whales
(Eschrictius robustus) are known to change direction--deflecting from
customary migratory paths--in order to avoid noise from seismic surveys
(Malme et al., 1984). Avoidance may be short-term, with animals
returning to the area once the noise has ceased (e.g., Bowles et al.,
1994; Goold 1996; Stone et al., 2000; Morton and Symonds, 2002; Gailey
et al., 2007). Longer-term displacement is possible, however, which may
lead to changes in abundance or distribution patterns of the affected
species in the affected region if habituation to the presence of the
sound does not occur (e.g., Blackwell et al., 2004; Bejder et al.,
2006; Teilmann et al., 2006).
A flight response is a dramatic change in normal movement to a
directed and rapid movement away from the perceived location of a sound
source. The flight response differs from other avoidance responses in
the intensity of the response (e.g., directed movement, rate of
travel). Relatively little information on flight responses of marine
mammals to anthropogenic signals exist, although observations of flight
responses to the presence of predators have occurred (Connor and
Heithaus, 1996). The result of a flight response could range from
brief, temporary exertion and displacement from the area where the
signal provokes flight to, in extreme cases, marine mammal strandings
(Evans and England, 2001). However, it should be noted that response to
a perceived predator does not necessarily invoke flight (Ford and
Reeves, 2008), and whether individuals are solitary or in groups may
influence the response.
Behavioral disturbance can also impact marine mammals in more
subtle ways. Increased vigilance may result in costs related to
diversion of focus and attention (i.e., when a response consists of
increased vigilance, it may come at the cost of decreased attention to
other critical behaviors such as foraging or resting). These effects
have generally not been demonstrated for marine mammals, but studies
involving fish and terrestrial animals have shown that increased
vigilance may substantially reduce feeding rates (e.g., Beauchamp and
Livoreil 1997; Fritz et al., 2002; Purser and Radford 2011). In
addition, chronic disturbance can cause population declines through
reduction of fitness (e.g., decline in body condition) and subsequent
reduction in reproductive success, survival, or both (e.g., Harrington
and Veitch, 1992; Daan et al. 1996; Bradshaw et al., 1998). However,
Ridgway et al. (2006) reported that increased vigilance in bottlenose
dolphins exposed to sound over a five-day period did not cause any
sleep deprivation or stress effects.
Many animals perform vital functions, such as feeding, resting,
traveling, and socializing, on a diel cycle (24-hour
[[Page 16208]]
cycle). Disruption of such functions resulting from reactions to
stressors such as sound exposure are more likely to be significant if
they last more than one diel cycle or recur on subsequent days
(Southall et al., 2007). Consequently, a behavioral response lasting
less than one day and not recurring on subsequent days is not
considered particularly severe unless it could directly affect
reproduction or survival (Southall et al., 2007). Note that there is a
difference between multi-day substantive behavioral reactions and
multi-day anthropogenic activities. For example, just because an
activity lasts for multiple days does not necessarily mean that
individual animals are either exposed to activity-related stressors for
multiple days or, further, exposed in a manner resulting in sustained
multi-day substantive behavioral responses.
Stress responses--An animal's perception of a threat may be
sufficient to trigger stress responses consisting of some combination
of behavioral responses, autonomic nervous system responses,
neuroendocrine responses, or immune responses (e.g., Seyle 1950; Moberg
2000). In many cases, an animal's first and sometimes most economical
(in terms of energetic costs) response is behavioral avoidance of the
potential stressor. Autonomic nervous system responses to stress
typically involve changes in heart rate, blood pressure, and
gastrointestinal activity. These responses have a relatively short
duration and may or may not have a significant long-term effect on an
animal's fitness.
Neuroendocrine stress responses often involve the hypothalamus-
pituitary-adrenal system. Virtually all neuroendocrine functions that
are affected by stress--including immune competence, reproduction,
metabolism, and behavior--are regulated by pituitary hormones. Stress-
induced changes in the secretion of pituitary hormones have been
implicated in failed reproduction, altered metabolism, reduced immune
competence, and behavioral disturbance (e.g., Moberg 1987; Blecha
2000). Increases in the circulation of glucocorticoids are also equated
with stress (Romano et al. 2004).
The primary distinction between stress (which is adaptive and does
not normally place an animal at risk) and distress is the cost of the
response. During a stress response, an animal uses glycogen stores that
can be quickly replenished once the stress is alleviated. In such
circumstances, the cost of the stress response would not pose serious
fitness consequences. However, when an animal does not have sufficient
energy reserves to satisfy the energetic costs of a stress response,
energy resources must be diverted from other functions. This state of
distress will last until the animal replenishes its energetic reserves
sufficient to restore normal function.
Relationships between these physiological mechanisms, animal
behavior, and the costs of stress responses are well-studied through
controlled experiments and for both laboratory and free-ranging animals
(e.g., Holberton et al. 1996; Hood et al. 1998; Jessop et al. 2003;
Krausman et al. 2004; Lankford et al. 2005). Stress responses due to
exposure to anthropogenic sounds or other stressors and their effects
on marine mammals have also been reviewed (Fair and Becker 2000; Romano
et al., 2002b) and, more rarely, studied in wild populations (e.g.,
Romano et al., 2002a). For example, Rolland et al., (2012) found that
noise reduction from reduced ship traffic in the Bay of Fundy was
associated with decreased stress in North Atlantic right whales. These
and other studies lead to a reasonable expectation that some marine
mammals will experience physiological stress responses upon exposure to
acoustic stressors and that it is possible that some of these would be
classified as ``distress.'' In addition, any animal experiencing TTS
would likely also experience stress responses (NRC, 2003).
Masking--Sound can disrupt behavior through masking, or interfering
with, an animal's ability to detect, recognize, or discriminate between
acoustic signals of interest (e.g., those used for intraspecific
communication and social interactions, prey detection, predator
avoidance, navigation) (Richardson et al. 1995). Masking occurs when
the receipt of a sound is interfered with by another coincident sound
at similar frequencies and at similar or higher intensity, and may
occur whether the sound is natural (e.g., snapping shrimp, wind, waves,
precipitation) or anthropogenic (e.g., pile driving, shipping, sonar,
seismic exploration) in origin. The ability of a noise source to mask
biologically important sounds depends on the characteristics of both
the noise source and the signal of interest (e.g., signal-to-noise
ratio, temporal variability, direction), in relation to each other and
to an animal's hearing abilities (e.g., sensitivity, frequency range,
critical ratios, frequency discrimination, directional discrimination,
age or TTS hearing loss), and existing ambient noise and propagation
conditions.
Masking of natural sounds can result when human activities produce
high levels of background sound at frequencies important to marine
mammals. Conversely, if the background level of underwater sound is
high (e.g. on a day with strong wind and high waves), an anthropogenic
sound source would not be detectable as far away as would be possible
under quieter conditions and would itself be masked. Busy ship channels
traverse Thimble Shoal. Commercial vessels including container ships
and cruise ships as well as numerous recreational frequent the area, so
background sound levels near the project area are likely to be
elevated, although to what degree is unknown.
The frequency range of the potentially masking sound is important
in determining any potential behavioral impacts. For example, low-
frequency signals may have less effect on high-frequency echolocation
sounds produced by odontocetes but are more likely to affect detection
of mysticete communication calls and other potentially important
natural sounds such as those produced by surf and some prey species.
The masking of communication signals by anthropogenic noise may be
considered as a reduction in the communication space of animals (e.g.,
Clark et al., 2009) and may result in energetic or other costs as
animals change their vocalization behavior (e.g., Miller et al., 2000;
Foote et al., 2004; Parks et al., 2007b; Di Iorio and Clark 2009; Holt
et al., 2009). Masking can be reduced in situations where the signal
and noise come from different directions (Richardson et al., 1995),
through amplitude modulation of the signal, or through other
compensatory behaviors (Houser and Moore 2014). Masking can be tested
directly in captive species (e.g., Erbe 2008), but in wild populations
it must be either modeled or inferred from evidence of masking
compensation. There are few studies addressing real-world masking
sounds likely to be experienced by marine mammals in the wild (e.g.,
Branstetter et al., 2013).
Masking affects both senders and receivers of acoustic signals and
can potentially have long-term chronic effects on marine mammals at the
population level as well as at the individual level. Low-frequency
ambient sound levels have increased by as much as 20 dB (more than
three times in terms of SPL) in the world's ocean from pre-industrial
periods, with most of the increase from distant commercial shipping
(Hildebrand 2009). All anthropogenic sound sources, but especially
chronic and lower-frequency signals (e.g., from vessel traffic),
[[Page 16209]]
contribute to elevated ambient sound levels, thus intensifying masking.
Underwater Acoustic Effects
Potential Effects of Pile Driving Sound
The effects of sounds from pile driving might include one or more
of the following: Temporary or permanent hearing impairment, non-
auditory physical or physiological effects, behavioral disturbance, and
masking (Richardson et al. 1995; Gordon et al. 2003; Nowacek et al.
2007; Southall et al. 2007). The effects of pile driving on marine
mammals are dependent on several factors, including the type and depth
of the animal; the pile size and type, and the intensity and duration
of the pile driving sound; the substrate; the standoff distance between
the pile and the animal; and the sound propagation properties of the
environment. Impacts to marine mammals from pile driving activities are
expected to result primarily from acoustic pathways. As such, the
degree of effect is intrinsically related to the frequency, received
level, and duration of the sound exposure, which are in turn influenced
by the distance between the animal and the source. The further away
from the source, the less intense the exposure should be. The substrate
and depth of the habitat affect the sound propagation properties of the
environment. In addition, substrates that are soft (e.g., sand) would
absorb or attenuate the sound more readily than hard substrates (e.g.,
rock), which may reflect the acoustic wave. Soft porous substrates
would also likely require less time to drive the pile, and possibly
less forceful equipment, which would ultimately decrease the intensity
of the acoustic source.
In the absence of mitigation, impacts to marine species could be
expected to include physiological and behavioral responses to the
acoustic signature (Viada et al. 2008). Potential effects from
impulsive sound sources like impact pile driving can range in severity
from effects such as behavioral disturbance to temporary or permanent
hearing impairment (Yelverton et al. 1973). Due to the nature of the
pile driving sounds in the project, behavioral disturbance is the most
likely effect from the proposed activity. Marine mammals exposed to
high intensity sound repeatedly or for prolonged periods can experience
hearing threshold shifts. Note that PTS constitutes injury, but TTS
does not (Southall et al. 2007).
Non-Auditory Physiological Effects
Non-auditory physiological effects or injuries that theoretically
might occur in marine mammals exposed to strong underwater sound
include stress, neurological effects, bubble formation, resonance
effects, and other types of organ or tissue damage (Cox et al. 2006;
Southall et al. 2007). Studies examining such effects are limited. In
general, little is known about the potential for pile driving to cause
non-auditory physical effects in marine mammals. Available data suggest
that such effects, if they occur at all, would presumably be limited to
short distances from the sound source and to activities that extend
over a prolonged period. The available data do not allow identification
of a specific exposure level above which non-auditory effects can be
expected (Southall et al. 2007) or any meaningful quantitative
predictions of the numbers (if any) of marine mammals that might be
affected in those ways. We do not expect any non-auditory physiological
effects because of mitigation that prevents animals from approach the
source too closely. Marine mammals that show behavioral avoidance of
pile driving, including some odontocetes and some pinnipeds, are
especially unlikely to incur non-auditory physical effects.
Disturbance Reactions
Responses to continuous sound, such as vibratory pile installation,
have not been documented as well as responses to pulsed sounds. With
both types of pile driving, it is likely that the onset of pile driving
could result in temporary, short term changes in an animal's typical
behavior and/or avoidance of the affected area. These behavioral
changes may include (Richardson et al. 1995): Changing durations of
surfacing and dives, number of blows per surfacing, or moving direction
and/or speed; reduced/increased vocal activities; changing/cessation of
certain behavioral activities (such as socializing or feeding); visible
startle response or aggressive behavior (such as tail/fluke slapping or
jaw clapping); avoidance of areas where sound sources are located; and/
or flight responses (e.g., pinnipeds flushing into water from haul-outs
or rookeries). Pinnipeds may increase their haul out time, possibly to
avoid in-water disturbance (Thorson and Reyff 2006). If a marine mammal
responds to a stimulus by changing its behavior (e.g., through
relatively minor changes in locomotion direction/speed or vocalization
behavior), the response may or may not constitute taking at the
individual level, and is unlikely to affect the stock or the species as
a whole. However, if a sound source displaces marine mammals from an
important feeding or breeding area for a prolonged period, impacts on
animals, and if so potentially on the stock or species, could
potentially be significant (e.g., Lusseau and Bejder 2007; Weilgart
2007).
The biological significance of many of these behavioral
disturbances is difficult to predict, especially if the detected
disturbances appear minor. However, the consequences of behavioral
modification could be expected to be biologically significant if the
change affects growth, survival, or reproduction. Significant
behavioral modifications that could potentially lead to effects on
growth, survival, or reproduction include:
Changes in diving/surfacing patterns (such as those
thought to cause beaked whale stranding due to exposure to military
mid-frequency tactical sonar);
Habitat abandonment due to loss of desirable acoustic
environment; and
Cessation of feeding or social interaction.
The onset of behavioral disturbance from anthropogenic sound
depends on both external factors (characteristics of sound sources and
their paths) and the specific characteristics of the receiving animals
(hearing, motivation, experience, demography) and is difficult to
predict (Southall et al. 2007).
Auditory Masking
Natural and artificial sounds can disrupt behavior by masking. The
frequency range of the potentially masking sound is important in
determining any potential behavioral impacts. Because sound generated
from in-water pile driving is mostly concentrated at low frequency
ranges, it may have less effect on high frequency echolocation sounds
made by porpoises. Any masking event that could possibly rise to Level
B harassment under the MMPA would occur concurrently within the zones
of behavioral harassment already estimated for vibratory and impact
pile driving, and which have already been taken into account in the
exposure analysis.
Airborne Acoustic Effects
Pinnipeds that occur near the project site could be exposed to
airborne sounds associated with pile driving that have the potential to
cause behavioral harassment, depending on their distance from pile
driving activities. Cetaceans are not expected to be exposed to
airborne sounds that would result in
[[Page 16210]]
harassment as defined under the MMPA.
Airborne noise would primarily be an issue for pinnipeds that are
swimming or hauled out near the project site within the range of noise
levels elevated above the acoustic criteria. The known harbor seal
haulouts at CBBT are 9.3 km away from the project area; however,
smaller numbers of harbor seals have been known to occasionally haul
out on the rocks near the HRBT (Danielle Jones, Naval Facilities
Engineering Command Atlantic, pers. comm., April 2019 as cited in the
application).
We recognize that pinnipeds in the water could be exposed to
airborne sound that may result in behavioral harassment when looking
with their heads above water or when hauled out. Most likely, airborne
sound would cause behavioral responses similar to those discussed above
in relation to underwater sound. For instance, anthropogenic sound
could cause hauled out pinnipeds to exhibit changes in their normal
behavior, such as reduction in vocalizations, or cause them to
temporarily abandon the area and move further from the source. Animals
that are hauled out would likely enter the water and be ``taken'' due
to underwater sound above the behavioral harassment thresholds, which
are in all cases larger than those associated with airborne sound.
Thus, the behavioral harassment of these animals would already
accounted for in these estimates of potential take. Therefore, we do
not believe that authorization of incidental take resulting from
airborne sound for pinnipeds is warranted, and airborne sound is not
discussed further here.
Marine Mammal Habitat Effects
The area likely impacted by the project is relatively small
compared to the available habitat for all impacted species and stocks,
and does not include any ESA-designated critical habitat. As previously
mentioned, no BIAs overlap with the project area. The HRCP's proposed
construction activities would not result in permanent negative impacts
to habitats used directly by marine mammals, but could have localized,
temporary impacts on marine mammal habitat including their prey by
increasing underwater SPLs and slightly decreasing water quality.
Increased noise levels may affect acoustic habitat (see masking
discussion above) and adversely affect marine mammal prey in the
vicinity of the project area (see discussion below). During pile
driving, elevated levels of underwater noise would ensonify areas near
the project where both fish and mammals occur and could affect foraging
success.
There are no known foraging hotspots or other ocean bottom
structure of significant biological importance to marine mammals
present in the marine waters of the project area. Therefore, the main
impact issue associated with the proposed activity would be temporarily
elevated sound levels and the associated direct effects on marine
mammals, as discussed previously in this document. The primary
potential acoustic impacts to marine mammal habitat are associated with
elevated sound levels produced by impact, vibratory, and DTH pile
installation in the project area. Physical impacts to the environment
such as construction debris are unlikely.
In-water pile driving would also cause short-term effects on water
quality due to increased turbidity.
In-Water Construction Effects on Potential Foraging Habitat
Pile installation may temporarily increase turbidity resulting from
suspended sediments. Any increases would be temporary, localized, and
minimal. In general, turbidity associated with pile installation is
localized to about a 25-foot (7.6 m) radius around the pile (Everitt et
al., 1980). Large cetaceans are not expected to be close enough to the
project activity areas to experience effects of turbidity, and any
small cetaceans and pinnipeds could avoid localized areas of turbidity.
Therefore, the impact from increased turbidity levels is expected to be
discountable to marine mammals.
Essential Fish Habitat (EFH) for several species or groups of
species overlaps with the project area including: Atlantic herring
(Clupea harengus), King Mackerel (Scomberomorus cavalla), Spanish
mackerel (Scomberomorus maculatus), and black sea bass (Centropristus
striata). Use of soft start procedure and bubble curtains (during
impact pile driving of 36-in steel piles at the Jet Grouting Trestle in
water depths greater than 20 ft) will reduce the impacts of underwater
acoustic noise to fish from pile driving activities. Avoidance by
potential prey (i.e., fish) of the immediate area due to the temporary
loss of this foraging habitat is also possible. The duration of fish
avoidance of this area after pile driving stops is unknown, but a rapid
return to normal recruitment, distribution and behavior is anticipated.
Any behavioral avoidance by fish of the disturbed area would still
leave significantly large areas of fish and marine mammal foraging
habitat in the nearby vicinity.
In-water Construction Effects on Potential Prey (Fish)--
Construction activities would produce continuous (i.e., vibratory pile
driving) and pulsed (i.e. impact driving, DTH) sounds. Fish react to
sounds that are especially strong and/or intermittent low-frequency
sounds. Short duration, sharp sounds can cause overt or subtle changes
in fish behavior and local distribution (summarized in Popper and
Hastings 2009). Hastings and Popper (2005) reviewed several studies
that suggest fish may relocate to avoid certain areas of sound energy.
Additional studies have documented physical and behavioral effects of
pile driving on fish, although several are based on studies in support
of large, multiyear bridge construction projects (e.g., Scholik and Yan
2001, 2002; Popper and Hastings, 2009). Sound pulses at received levels
of 160 dB may cause subtle changes in fish behavior. SPLs of 180 dB may
cause noticeable changes in behavior (Pearson et al., 1992; Skalski et
al., 1992). SPLs of sufficient strength have been known to cause injury
to fish and fish mortality (summarized in Popper et al., 2014).
The most likely impact to fish from pile driving activities at the
project area would be temporary behavioral avoidance of the area. The
duration of fish avoidance of this area after pile driving stops is
unknown, but a rapid return to normal recruitment, distribution and
behavior is anticipated. In general, impacts to marine mammal prey
species are expected to be minor and temporary.
In summary, given the relatively small areas being affected, pile
driving activities associated with the proposed action are not likely
to have a permanent, adverse effect on any fish habitat, or populations
of fish species. Thus, we conclude that impacts of the specified
activity are not likely to have more than short-term adverse effects on
any prey habitat or populations of prey species. Further, any impacts
to marine mammal habitat are not expected to result in significant or
long-term consequences for individual marine mammals, or to contribute
to adverse impacts on their populations.
Estimated Take
This section provides an estimate of the number of incidental takes
proposed for authorization 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
[[Page 16211]]
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 proposed 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 proposed for authorization 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 each 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 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 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 HRCP's proposed activities include the use of continuous,
non-impulsive (vibratory pile driving) and impulsive (impact pile
driving; DTH hammer) sources and therefore, the 120 and 160 dB re 1
[mu]Pa (rms) are applicable.
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. HRCP's proposed
activity includes the use of impulsive (impact pile driving, DTH
drilling) and non-impulsive (vibratory pile driving) sources.
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.
[[Page 16212]]
Note: Peak sound pressure (Lpk) has a reference value of 1 [mu]Pa, and cumulative sound exposure level (LE) has
a reference value of 1[mu]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 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). HRCP has proposed to employ bubble curtains
during impact pile driving of 36-in steel piles at the Jet Grouting
Trestle in water depths greater than 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-inch steel pile................ 168 \a\ City and Borough of
Sitka Department of
Public Works 2017.
36-inch steel pile................ 167 \b\ DoN 2015.
24-inch steel pile................ 161 \c\ 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-inch steel pile.................... 193 183 210 Chesapeake Tunnel Joint
Venture 2018.
36-inch steel pile, attenuated *...... 186 176 203 DoN 2015; Chesapeake
Tunnel Joint Venture
2018.
54-inch concrete cylinder pile........ 176 174 192 MacGillivray et al.,
2007.
30-inch concrete square pile.......... 176 174 192 MacGillivray et al.,
2007.
24-inch 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.
*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, 83 FR 12152, 84 FR 22453, and 84 FR 34134).
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
[[Page 16213]]
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 sound
source levels (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.
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-inch diameter steel pipe
piles with SSLs of 161, 167, and 168 dB rms respectively, the 24- and
36-inch would 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-
inch 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-inch 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-inch steel pipe piles throughout the project area (Table 7).
[[Page 16214]]
[GRAPHIC] [TIFF OMITTED] TN20MR20.001
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
[[Page 16215]]
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 6 sets of 3 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 0, 1, 2, 3, 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]
--------------------------------------------------------------------------------------------------------------------------------------------------------
36-in 42-in steel piles 42-in steel piles
24-in 36-in steel piles 42-in (multiple hammer (multiple hammer
steel piles steel piles (at TBM steel piles event--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 6 2 6 * 6 ** 9
Duration to drive a single pile (min)....................... 30 50 60 30 30 30
Propagation (xLogR)......................................... 15 15 15 15 15 15
Distance of source level measurement (meters)............... 10 10 10 10 10 10
--------------------------------------------------------------------------------------------------------------------------------------------------------
* (3 piles installed simultaneously, 6 piling events)
** (2 piles installed simultaneously, 9 piling events)
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, South Island DTH
Trestle and South Trestle test pile -----------------------------------------------------------------
----------- program North
--------------------------------- TBM Conveyor TBM Shore Jet Conveyor
Platform Trestle Platform Work Grouting Trestle
36-in 24-in 30-in 54-in 36-in 36-in 36-in Trestle Trestle 36-in
steel concrete concrete concrete steel steel steel 36-in 36-in steel
piles square square cylinder piles piles piles steel steel piles
piles piles
--------------------------------------------------------------------------------------------------------------------------------------------------------
Source Level (SEL)........................ 183 166 174 174 183 183 180 180 180 180
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 10 10 10 10 10 10 10 10 10 10
(meters).................................
--------------------------------------------------------------------------------------------------------------------------------------------------------
[[Page 16216]]
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 level at 10 m ---------------------------------------------------------------------------------------
Low- Mid- High- Low- Mid- High-
frequency frequency frequency Phocid frequency frequency frequency Phocid
cetaceans cetaceans cetaceans cetaceans cetaceans cetaceans
--------------------------------------------------------------------------------------------------------------------------------------------------------
Vibratory Pile Driving
--------------------------------------------------------------------------------------------------------------------------------------------------------
24-in steel pile installation (All 161 dB SPL................ 15 2 21 9 <0.01
Locations).
36-in steel pile installation (All 167 dB SPL................ 32 3 47 20 <0.01
Locations).
36-in steel pile installation (TMB 167 dB SPL................ 28 3 41 17 <0.01
Platform).
42-in steel pile installation (All 168 dB SPL................ 42 4 62 26 <0.10
Locations).
--------------------------------------------------------------------------------------------------------------------------------------------------------
Impact Pile for the Jet Grouting Trestle
--------------------------------------------------------------------------------------------------------------------------------------------------------
36-in steel pile installation....... 183 dB SEL................ 243 9 290 130 0.11 <0.01 0.16 <0.10
36-in steel pile installation 176 dB SEL................ 83 3 99 45 0.014 <0.001 0.20 <0.01
(attenuated).
--------------------------------------------------------------------------------------------------------------------------------------------------------
Impact Pile Driving North Trestle
--------------------------------------------------------------------------------------------------------------------------------------------------------
36-in steel pile installation (North 183 dB SEL................ 243 9 290 130 0.19 <0.001 0.26 0.05
Shore Work Trestle).
--------------------------------------------------------------------------------------------------------------------------------------------------------
Impact Pile Driving for North Trestle, Willoughby Bay, and South Trestle Test Pile Program
--------------------------------------------------------------------------------------------------------------------------------------------------------
24-in concrete square pile 166 dB SEL................ 121 5 144 65 0.05 <0.001 0.07 0.01
installation/removal.
30-in concrete square pile 174 dB SEL................ 412 15 490 221 0.53 <0.001 0.75 0.15
installation/removal.
54-in concrete square pile 174 dB SEL................ 412 15 490 221 0.53 <0.001 0.75 0.15
installation/removal.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Impact Pile Driving for South Island
--------------------------------------------------------------------------------------------------------------------------------------------------------
36-in steel pile installation (TBM 183 dB SEL................ 243 9 290 130 0.11 <0.001 0.16 <0.10
Platform).
36-in steel pile installation 183 dB SEL................ 243 9 290 130 0.11 <0.001 0.16 <0.10
(Conveyor Trestle).
--------------------------------------------------------------------------------------------------------------------------------------------------------
DTH Drilling
--------------------------------------------------------------------------------------------------------------------------------------------------------
36-in steel pile installation (TBM 180 dB SEL................ 1,171 42 1,395 627 2.437 <0.01 3.446 0.704
Platform).
36-in steel pile installation (North 180 dB SEL................ 1,534 55 1,827 821 3.615 <0.01 4.790 1.548
Shore Work Trestle).
36-in steel pile installation (Jet 180 dB SEL................ 1,534 55 1,827 821 3.615 <0.01 5.908 1.548
Grouting Trestle).
36-in steel pile installation 180 dB SEL................ 1,534 55 1,827 821 3.615 <0.01 5.908 1.548
(Conveyor Trestle).
--------------------------------------------------------------------------------------------------------------------------------------------------------
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 proposed activities.
[[Page 16217]]
Table 12--Radial Distances (Meters) to Relevant Behavioral Isopleths and Associated Ensonified Areas (Square
Kilometers (km\2\)) Using the Practical Spreading Model
----------------------------------------------------------------------------------------------------------------
Distance to Level B Level B harassment
Location and component Method and pile type 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 = 160 dB)
----------------------------------------------------------------------------------------------------------------
North Shore Work Trestle................ 36-in steel piles......... 215 0.145
TBM Platform............................ 36-in steel piles......... 215 0.087
Jet Grouting Trestle.................... 36-in steel piles......... 215 0.087
Conveyor Trestle........................ 36-in steel piles......... 215 0.087
----------------------------------------------------------------------------------------------------------------
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 117 0.04
piles.
Test Pile Program....................... 30-in concrete square 117 0.04
piles.
Test Pile Program....................... 24-in concrete square 117 0.04
piles.
----------------------------------------------------------------------------------------------------------------
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.
In some cases, particularly during DTH drilling and the test pile
program, 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 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 Proposed Monitoring and Reporting section.
[[Page 16218]]
Table 13--Calculated Distances to Level B Harassment Zones for Multiple
Hammer Additions
------------------------------------------------------------------------
Distance to Level
Combined SSL (dB) B 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. Take by Level A and B harassment is proposed for
authorization.
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 proposed. 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 daily sighting rates of marine mammals 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). Many of the data from the Engelhaupt et al.
(2016) study were collected from the coastal region outside Chesapeake
Bay, where bottlenose dolphin numbers are greater than in the project
area. For this analysis, only bottlenose dolphin sightings located west
of 76[deg]10' (76.16667[deg]) were used, which includes the largest
area that could be ensonified by project-related noise. Sighting rates
(number of dolphins per day) were determined for each of the four
seasons (Table 14). The number of sightings per season ranged from 5 in
spring to 24 in fall; no bottlenose dolphins were sighted in the winter
months. Bottlenose dolphin abundance was highest in the fall, with 24
sightings representing 245 individuals, followed by the spring (n =
156), and summer (n = 115). Therefore, the average daily sighting rate
of bottlenose dolphins across spring, summer, and fall were averaged to
estimate that 20.33 bottlenose dolphins per day potentially could be
exposed to project-related noise (Table 14).
Table 14--Average Daily Sighting Rates of Bottlenose Dolphins Within the
Project Area
------------------------------------------------------------------------
Number of Average number of
Season sightings per dolphins sighted
season per day
------------------------------------------------------------------------
Spring, March-May................. 5 17.33
Summer, June-August............... 14 16.43
Fall, September-November.......... 24 27.22
Winter, December-February......... 0 0.00
Average Dolphins: Spring, ................. 20.33
Summer, and Fall.............
------------------------------------------------------------------------
Source: Engelhaupt et al., 2016.
The number of days of pile installation is estimated to be 312
days. Therefore, the instances of take by Level B harassment proposed
for this activity is 6,343 for bottlenose dolphins (20.33 bottlenose
dolphins per day multiplied by 312 days). 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 CBBT rock
armor and portal islands from November 2014 through May 2018 (Rees et
al., 2016; Jones et al., 2018). The number of harbor seals sighted by
month from 2014 through 2018, in the Chesapeake Bay waters, near the
project area, ranged from 0 to 170 individuals (Table 15). Harbor seals
are not expected to be present in the Chesapeake Bay during the months
of June through October (Table 15 and Table 16).
[[Page 16219]]
Table 15--Summary of Historical Harbor Seal Sightings by Month From 2014 to 2018
--------------------------------------------------------------------------------------------------------------------------------------------------------
Number of individual harbor seals
---------------------------------------------------------------------------------------------------------------------------------------------------------
Monthly
Month 2014 2015 2016 2017 2018 average
--------------------------------------------------------------------------------------------------------------------------------------------------------
January................................................. .............. .............. 33 120 170 107.7
February................................................ .............. 39 80 106 159 96
March................................................... .............. 55 61 41 0 39.3
April................................................... .............. 10 1 3 3 4.3
May..................................................... .............. 3 0 0 0 0.8
-----------------------------------------------------------------------------------------------
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................................................ 1 0 1 0 .............. 0.5
December................................................ 4 9 24 8 .............. 11.3
--------------------------------------------------------------------------------------------------------------------------------------------------------
Source: Rees et al., 2016; Jones et al., 2018.
Note: Seal counts began in November 2014 and were collected for four field seasons (2014/2015, 2015/2016, 2016/2017, and 2017/2018) ending in May 2018.
In January 2015, no surveys were conducted.
Table 16--Average Number of Individual Harbor Seal Sightings Summarized
by Season
------------------------------------------------------------------------
Average number of
Season individuals per
season
------------------------------------------------------------------------
Spring (March-May)................................... 45
Summer (June-August)................................. 0
Fall (September-November)............................ 1
Winter (December-February)........................... 215
Total Harbor Seals Per Year...................... 261
------------------------------------------------------------------------
Note: Data presented is from Table 15.
Using the above data, the total instances of take by Level B
harassment for harbor seals is 261. The largest Level A harassment
isopleth calculated from DTH drilling of 36-in steel pipe piles for
harbor seals is 821 meters (Table 11). The area of this Level A
harassment zone is 1.55 km\2\, which is larger than the area of the
Level B harassment zone (0.015 km\2\). The known harbor seal haulouts
at CBBT are 9.3 km away from the project area; however, smaller numbers
of harbor seals have been known to occasionally haul out on the rocks
near the HRBT (Danielle Jones, Naval Facilities Engineering Command
Atlantic, pers. comm., April 2019 as cited in the application). It is
unlikely that harbor seals using the CBBT haulouts will approach the
project area within 821 m of pile installation and potentially incur
Level A harassment. On approximately 21 percent of the pile driving
days, the calculated Level A harassment zone would exceed the size of
the calculated Level B harassment zone during DTH drilling. To account
for any seals that may haul out on the rocks near HRBT, particularly
during DTH drilling, HRCP requests 55 instances of take by Level A
harassment of harbor seals as part of the 261 total instances of take
requested. If any seals are hauled out on rocks near the HRBT, it is
likely they will enter the water and be taken from Level B harassment
in-water. Therefore, we are not proposing any in-air harassment takes
for harbor seals.
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
17). Gray seals are not expected to be present in the Chesapeake Bay
during the months of June through October (Table 17 and Table 18).
Table 17--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
[[Page 16220]]
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 18--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 17.
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 estimate that nine
instances of take by Level B harassment of gray seals could occur
(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 take by Level A harassment of gray
seals.
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
6 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. The area of this Level A harassment
zone is 5.9 km\2\, which is larger than the area of the Level B
harassment zone (0.015 km\2\). Because of this disparity in sizes of
the calculated zones, and 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
requests a small number of takes by Level A harassment for harbor
porpoises during the project. On approximately 21 percent of the pile
driving days, the calculated Level A harassment zone would exceed the
size of the calculated Level B harassment zone during DTH drilling. It
is anticipated that two harbor porpoises may enter the calculated Level
A harassment zone during this time. Therefore, we propose to authorize
a total of 2 instances of take by Level A harassment.
Table 19 below summarizes the proposed authorized take for all the
species described above as a percentage of stock abundance.
Table 19--Proposed Take by Level A and B Harassment and as a Percentage of Stock Abundance
--------------------------------------------------------------------------------------------------------------------------------------------------------
Total Takes
Species Stock Proposed Level Proposed Level proposed for Percentage of stock
A takes B takes authorization
--------------------------------------------------------------------------------------------------------------------------------------------------------
Humpback whale....................... Gulf of Maine........... 0 12 12 Less than 2 percent.
Harbor porpoise...................... Gulf of Maine/Bay of 2 4 6 Less than 1 percent.
Fundy.
Bottlenose dolphin................... WNA Coastal, Northern 0 3,063 3,063 46.13.
Migratory \a\.
WNA Coastal, Southern 0 3,063 3,063 81.66.
Migratory \a\.
NNCES \a\............... 0 216 216 26.25.
Harbor seal.......................... Western North Atlantic.. 55 206 261 Less than 1 percent.
Gray seal............................ Western North Atlantic.. 0 9 9 Less than 1 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.
[[Page 16221]]
Proposed 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 proposed
IHAs:
Timing Restrictions
All work will be conducted during conditions of good visibility. If
poor environmental conditions restrict full visibility of the shutdown
zone, pile installation would be delayed.
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 shall
cease and vessels shall 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 species which correspond to the Level A harassment
zones (see Table 11). 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 zones for
all pile driving activities where the calculated Level A harassment
zone is less than 10 m as described in Table 11.
If multiple vibratory hammering occurs, 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.
Bubble Curtain
HRCP would 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 shall ensure
100 percent mudline and/or rock bottom contact. No parts of the ring or
other objects shall 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 of all steel piles 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 thirty-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 thirty
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 proposed measures, NMFS has
determined that the proposed 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.
Proposed 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
proposed 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);
[[Page 16222]]
[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 permitted for Level B harassment
take has been permitted 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) or 160 dB rms (for impact pile driving and DTH
drilling). 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 proposed 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 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
shall record all incidents of marine mammal occurrence, regardless of
distance from activity, and shall document any behavioral reactions in
concert with distance from piles being driven/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 thirty 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.
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
[[Page 16223]]
more than 12 hours in a 24-hour period (to reduce PSO fatigue).
Monitoring of pile driving shall be conducted by qualified, NMFS-
approved PSOs, who shall have no other assigned tasks during monitoring
periods. The HRCP shall adhere to the following conditions when
selecting PSOs:
[ssquf] Independent PSOs shall 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 shall be designated. The lead
observer must have prior experience working as a marine mammal observer
during construction; and
[ssquf] The HRCP shall submit PSO CVs for approval by NMFS for all
observers prior to monitoring. The HRCP shall 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 shall report the
incident to the Office of Protected Resources (OPR), NMFS and to the
Greater Atlantic Region New England/Mid-Atlantic Regional Stranding
Coordinator as soon as feasible. 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 shall 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 shall provide a final report within 30 days following resolution
of NMFS' comments on the draft report. Reports shall 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
[[Page 16224]]
incorporated into this analysis via their impacts on the environmental
baseline (e.g., as reflected in the regulatory status of the species,
population size and growth rate where known, ongoing sources of human-
caused mortality, or ambient noise levels).
Pile driving activities associated with the proposed 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 proposed 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 proposed
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 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.
HRCP's proposed 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 proposed 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
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 preliminary 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 (BIAs or ESA-
designated critical habitat); and
The presumed efficacy of the proposed 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 proposed monitoring and
mitigation measures, NMFS preliminarily finds that the total marine
mammal take from the proposed 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
[[Page 16225]]
as the temporal or spatial scale of the activities.
The proposed 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.
Detailed descriptions of the stocks' ranges have been provided in
Description of Marine Mammals in the Area of Specified Activities.
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 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 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 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 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 like
a small resident community of NNCES dolphins 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.). 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 preliminary 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 Bay;
The 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 Bay.
Based on the analysis contained herein of the proposed activity
(including the proposed mitigation and monitoring measures) and the
anticipated take of marine mammals, NMFS preliminarily finds that small
numbers of marine mammals will be taken relative to the population size
of the affected species or stocks.
Unmitigable Adverse Impact Analysis and Determination
There are no relevant subsistence uses of the affected marine
mammal stocks or species implicated by this action. Therefore, NMFS has
determined that the total taking of affected species or stocks would
not have an unmitigable adverse impact on the availability of such
species or stocks for taking for subsistence purposes.
Endangered Species Act (ESA)
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
[[Page 16226]]
mammals are expected or proposed for authorization. Therefore, NMFS has
determined that consultation under section 7 of the ESA is not required
for this action.
Proposed Authorization
As a result of these preliminary determinations, NMFS proposed to
issue 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 from the date of issuance, provided the previously mentioned
mitigation, monitoring, and reporting requirements are incorporated.
Donna S. Wieting,
Director, Office of Protected Resources, National Marine Fisheries
Service.
[FR Doc. 2020-05807 Filed 3-19-20; 8:45 am]
BILLING CODE 3510-22-P