Take of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to the Hampton Roads Bridge-Tunnel Expansion Project, Hampton-Norfolk, Virginia, 16194-16226 [2020-05807]

Agencies

• DEPARTMENT OF COMMERCE
• National Oceanic and Atmospheric Administration

[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]



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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

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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

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[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

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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
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                           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
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                   North Trestle (Segment 1b)
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
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.
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                    North Island (Segment 2a)
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Moorings...............................  42-inch Steel Pipe.......          80           60  ..........  ..........          80          30  ...........           6           40             13
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                   Willoughby Bay (Segment 3c)
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
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