1588 Federal Register / Vol. 86, No. 5 / Friday, January 8, 2021 / Proposed Rules 

DEPARTMENT OF COMMERCE 

National Oceanic and Atmospheric 

Administration 

50 CFR Part 217 

[Docket No. 201228–0360] 

RIN 0648–BK21 

Taking Marine Mammals Incidental to 

the Hampton Roads Bridge Tunnel 

Expansion Project in Norfolk, Virginia 

AGENCY: National Marine Fisheries 

Service (NMFS), National Oceanic and 

Atmospheric Administration (NOAA), 

Commerce. 

ACTION: Proposed rule; request for 

comments and information. 

SUMMARY: NMFS has received a request 

from the Hampton Roads Connector 

Partners (HRCP) for authorization to 

take small numbers of marine mammals 

incidental to pile driving and removal 

activities at the Hampton Roads Bridge 

Tunnel Expansion Project (HRBT) in 

Norfolk, Virginia over the course of five 

years (2021–2026). Pursuant to the 

Marine Mammal Protection Act 

(MMPA), NMFS is proposing 

regulations to govern that take, and 

requests comments on the proposed 

regulations. 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 February 8, 

2021. 

ADDRESSES: You may submit comments, 

identified by NOAA–NMFS–2020–0164, 

by the following method: 

• Comment submissions: Submit all 

public comments via the Federal 

eRulemaking Portal, Go to 

www.regulations.gov/ 

#!docketDetail;D=NOAA-NMFS-2020- 

0164, click the ‘‘Comment Now!’’ icon, 

complete the required fields, and enter 

or attach your comments. 

Instructions: Comments sent by any 

other method, to any other address or 

individual, or received after the end of 

the comment period, may not be 

considered by NMFS. All comments 

received are a part of the public record 

and will generally be posted for public 

viewing on www.regulations.gov 

without change. All personal identifying 

information (e.g., name, address), 

confidential business information, or 

otherwise sensitive information 

submitted voluntarily by the sender will 

be publicly accessible. NMFS will 

accept anonymous comments (enter ‘‘N/ 

A’’ in the required fields if you wish to 

remain anonymous). Attachments to 

electronic comments will be accepted in 

Microsoft Word, Excel, or Adobe PDF 

file formats only. 

FOR FURTHER INFORMATION CONTACT: 

Robert Pauline, Office of Protected 

Resources, NMFS, (301) 427–8401. 

SUPPLEMENTARY INFORMATION: 

Availability 

A copy of HRCP’s application and any 

supporting documents, as well as a list 

of the references cited in this document, 

may be obtained online at: https://

www.fisheries.noaa.gov/action/ 

incidental-take-authorization-hamptonroads-bridge-tunnel-expansion-projecthampton-0. In case of problems 

accessing these documents, please call 

the contact listed above (see FOR

FURTHER INFORMATION CONTACT). 

Purpose and Need for Regulatory 

Action 

This proposed rule would establish a 

framework under the authority of the 

MMPA (16 U.S.C. 1361 et seq.) to allow 

for the authorization of take of marine 

mammals incidental to construction 

activities including pile installation and 

pile replacement, as part of the (HRBT). 

The HRBT is a major road transport 

infrastructure project conducted by 

HRCP along the existing I–64 highway 

in Virginia, consisting of roadway 

improvements, trestle bridges, and 

bored tunnels crossing the James River 

between Norfolk and Hampton. The 

project will address severe traffic 

congestion at the existing HRBT 

crossing by increasing traffic capacity 

and upgrading lanes. We received an 

application from HRCP requesting fiveyear regulations and authorization to 

take multiple species of marine 

mammals. Take would occur by Level A 

and Level B harassment only incidental 

to impact pile driving, vibratory pile 

driving, vibratory pile removal, jetting, 

and down-the-hole (DTH) pile 

installation. Please see Background 

below for definitions of harassment. 

Legal Authority for the Proposed Action 

Section 101(a)(5)(A) of the MMPA (16 

U.S.C. 1371(a)(5)(A)) directs the 

Secretary of Commerce 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 for up to five years 

if, after notice and public comment, the 

agency makes certain findings and 

issues regulations that set forth 

permissible methods of taking pursuant 

to that activity and other means of 

effecting the ‘‘least practicable adverse 

impact’’ on the affected species or 

stocks and their habitat (see the 

discussion below in the Proposed 

Mitigation section), as well as 

monitoring and reporting requirements. 

Section 101(a)(5)(A) of the MMPA and 

the implementing regulations at 50 CFR 

part 216, subpart I provide the legal 

basis for issuing this proposed rule 

containing five-year regulations, and for 

any subsequent LOAs. As directed by 

this legal authority, this proposed rule 

contains mitigation, monitoring, and 

reporting requirements. 

Summary of Major Provisions Within 

the Proposed Rule 

Following is a summary of the major 

provisions of this proposed rule 

regarding HRCP’s construction 

activities. These measures include: 

• Shutdown of construction activities 

under certain circumstances to avoid 

injury of marine mammals. 

• Required monitoring of the 

construction areas to detect the presence 

of marine mammals before beginning 

construction activities. 

• Soft start for impact pile driving to 

allow marine mammals the opportunity 

to leave the area prior to initiating 

impact pile driving at full power. 

• Use of bubble curtains during 

impact driving of steel piles except 

when water depth is less than 20 feet. 

Background 

Section 101(a)(5)(A) of the MMPA (16 

U.S.C. 1361 et seq.) directs 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, regulations are 

issued, and notice is provided to the 

public. 

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), and if the permissible 

methods of taking and requirements 

pertaining to the mitigation, monitoring 

and reporting of the takings are set forth. 

NMFS has defined ‘‘negligible 

impact’’ in 50 CFR 216.103 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. 


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Except with respect to certain 

activities not pertinent here, the MMPA 

defines ‘‘harassment’’ as: Any act of 

pursuit, torment, or annoyance which (i) 

has the potential to injure a marine 

mammal or marine mammal stock in the 

wild (Level A harassment); or (ii) has 

the potential to disturb a marine 

mammal or marine mammal stock in the 

wild by causing disruption of behavioral 

patterns, including, but not limited to, 

migration, breathing, nursing, breeding, 

feeding, or sheltering (Level B 

harassment). 

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 the 

proposed action (i.e., the promulgation 

of regulations and subsequent issuance 

of an incidental take authorization) with 

respect to potential impacts on the 

human environment. 

This action is consistent with 

categories of activities identified in 

Categorical Exclusion B4 (Incidental 

harassment authorizations (IHAs) 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 

incidental take authorization request. 

Summary of Request 

On November 19, 2019, NMFS 

received an application from HRCP 

requesting authorization for take of 

marine mammals incidental to 

construction activities related to a major 

road transport infrastructure project 

along the existing I–64 highway in 

Virginia, consisting of roadway 

improvements, trestle bridges, and 

bored tunnels crossing Hampton Roads 

between Norfolk and Hampton, 

Virginia. HRCP submitted a revised 

LOA application on June 27, 2020 

which included changes to construction 

methods. We determined the 

application was adequate and complete 

on September 29, 2020. On October 7, 

2020 (85 FR 63256), we published a 

notice of receipt (NOR) of HRCP’s 

application in the Federal Register, 

requesting comments and information 

related to the request for thirty days. No 

comments were received on the NOR. 

HRCP requests authorization to take a 

small number of five species of marine 

mammals by Level A and Level B 

harassment only. Neither HRCP nor 

NMFS expects serious injury or 

mortality to result from this activity. 

The proposed regulations would be 

valid for five years (2021–2026). Note 

that HRCP had previously applied for an 

IHA to cover initial in-water pile driving 

work. NMFS issued the IHA on July 10, 

2020 (85 FR 48153; August 10, 2020). 

Description of Proposed Activity 

HRCP is proposing to conduct 

construction activities associated with 

the HRBT project. This is a major road 

transport infrastructure project along the 

existing I–64 highway in Virginia, 

consisting of roadway improvements, 

trestle bridges, and bored tunnels 

crossing Hampton Roads between 

Norfolk and Hampton. The Project will 

address severe traffic congestion at the 

existing HRBT crossing by increasing 

capacity. The Project will include 

widening I–64 to create an eight-lane 

facility with a consistent six-lanes 

between the I–64/I–664 and I–64/I–564 

Interchange, which could expand to 

eight-lanes during peak travel periods 

with the use of drivable shoulder lanes 

within the Project limits. The Project 

will include the construction of two 

new two-lane tunnels, expansion of the 

existing portal islands, and full 

replacement of the existing North and 

South bridge-trestles. 

The proposed HRBT project would 

include pile installation and pile 

removal. Pile installation methods will 

include impact and vibratory driving, 

jetting, and DTH pile installation. Pile 

removal techniques for temporary piles 

will include vibratory pile removal or 

cutting three feet below the mudline. 

Impact pile installation is projected to 

take place at 3 to 4 locations 

simultaneously and there is the 

potential for as many as 7 pile 

installation locations operating 

concurrently with different hammer 

types. Pile installation and removal can 

occur at variable rates, from a few 

minutes one day to several hours the 

next. HRCP anticipates that between 1 

to 10 piles could be installed per day, 

depending on project scheduling. 

The proposed action may incidentally 

expose marine mammals occurring in 

the vicinity to elevated levels of 

underwater sound, thereby resulting in 

incidental take, by Level A and Level B 

harassment. 

Dates and Duration 

The proposed regulations would be 

valid for a period of five years (2021– 

2026). The specified activities may 

occur at any time during the five-year 

period of validity of the proposed 

regulations. HRCP expects pile driving 

and removal to occur six days per week. 

The overall number of anticipated days 

of pile installation and removal is 312 

each year for years 1–4 and 181 days for 

year 5, based on a 6-day work week. 

Over five years this would result in an 

estimated total of 1,429 days of in-water 

construction work, which may last from 

a few minutes up to several hours per 

day. 

HRCP plans to conduct work during 

daylight hours although pile installation 

and removal 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). In order to maintain pile 

integrity and follow safety precautions, 

pile installation or removal will 

continue after dark only for piles 

already in the process of being installed 

or removed. Installation or removal will 

not commence on new piles after dark. 

Specific Geographic Region 

The proposed project area is located 

in the waterway of Hampton Roads 

adjacent to the existing bridge and 

island structures of the HRBT. Hampton 

Roads is located at the confluence of the 

James River, the Elizabeth River, the 

Nansemond River, Willoughby Bay, and 

the Chesapeake Bay. Navigational 

channels are maintained by the U.S. 

Army Corps of Engineers (USACE) 

within Hampton Roads to provide 

transit to the many ports in the region. 

Maintained navigation channels near 

the project area consist of: 

• Norfolk Harbor Entrance Reach 

(1,000 to 1,400 feet wide and is 

maintained at a depth of 50 feet Mean 

Lower Low Water [MLLW]); 

• Hampton Creek Entrance Channel 

(200 feet wide and is maintained at a 

depth of 12 feet MLLW); 

• Phoebus Channel (150 feet wide 

and is maintained at a depth of 12 feet 

MLLW); and 

• Willoughby Channel (200 feet wide 

and is maintained at a depth of 10 feet 

MLLW). 

Sediments are mostly fine and 

medium sands with various amounts of 

coarse sand and gravel, and low organic 

carbon content. There is no naturally 

occurring rocky or cobble bottom 

present at or adjacent to the project area. 

The North Shore in Hampton contains 

estuarine intertidal sandy shore, 


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estuarine intertidal reef, as well as 

submerged aquatic vegetation (SAV) in 

shallow estuarine open water. The 

North Trestle is located in estuarine 

open water with depths less than 15 feet 

below MLLW. The North Island is 

surrounded by estuarine intertidal 

sandy shore and rocky shore. Estuarine 

open water depths are primarily less 

than 15 feet 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 to 30 feet below MLLW), with 

a pocket of deeper water approximately 

35 feet below MLLW to the west. The 

South Trestle is primarily located in 

estuarine open water with depths less 

than 15 feet below MLLW, with the 

exception of deep water (15 to 30 feet 

below MLLW) near the South Island 

approach. The north shore of 

Willoughby Bay contains estuarine 

intertidal sandy shore with two small 

pockets of estuarine intertidal emergent 

wetlands to the east. The Willoughby 

Bay Trestles are located in estuarine 

open waters with depths of less than 15 

feet below MLLW, with the entire west 

bound trestle in water less than 6.6 feet 

below MLLW. Willoughby Bay contains 

an estuarine intertidal sandy shore and 

consists of estuarine open water with 

depths to 15 feet below MLLW. 

A map of the HRBT Project Area is 

provided in Figure 1 below and Figures 

1–1 and 2–1 in HRCP’s application. 

BILLING CODE 3510–22–P 


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BILLING CODE 3510–22–C 

The proposed 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 and 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 Bridges, and Oastes Creek 

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. 

TABLE 1—HRBT EXPANSION PROJECT DESIGN SEGMENTS

Project design segment number and name Construction area 

Segment 1a (Hampton) ................................................................................................................................................................. Area 1. 

Segment 1b (North Trestle-Bridges) 1 ............................................................................................................................................ Area 2. 

Segment 2a (Tunnel) 1 ................................................................................................................................................................... Area 3. 


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TABLE 1—HRBT EXPANSION PROJECT DESIGN SEGMENTS—Continued 

Project design segment number and name Construction area 

Segment 3a (South Trestle-Bridge) 1 ............................................................................................................................................. Area 2. 

Segment 3b (Willoughby Spit) 1 ..................................................................................................................................................... Area 4. 

Segment 3c (Willoughby Bay Trestle-Bridges) 1 ............................................................................................................................ Area 2. 

Segment 3d (4th View Street Interchange) ................................................................................................................................... Area 4. 

Segment 4a (Norfolk-Navy) ........................................................................................................................................................... Area 4. 

Segment 5a (I–564 Interchange) ................................................................................................................................................... Area 4. 

1 Indicates segment includes in-water construction activities. 

The proposed project design is 

divided into five segments as shown in 

Table 1. However, only the subsegments identified in Table 1 and 

described below would include in-water 

marine construction activities that have 

the potential to affect marine mammals: 

Segment 1b—North Trestle-Bridges 

This segment includes new and 

replacement north tunnel approach 

trestles, This segment is located in 

Construction Area 2 as shown in Figure 

1 above and Figure 1–1 in HRCP’s 

application. 

Temporary Work Trestles for Bridge 

Construction at the North Trestle— 

Several temporary work trestles will 

support construction of the permanent 

eastbound and westbound North 

Trestle-Bridges. The temporary North 

Shore Work Trestle will support 

construction of the permanent 

eastbound North Trestle-Bridge in the 

shallow water (<4 to 6 feet Mean Low 

Water (MLW)) closer to the North Shore, 

avoiding the need to dredge or deepen 

this area. The temporary North Shore 

Work Trestle (194 36-inch steel pipe 

piles) will be installed under the 2020 

IHA (85 FR 48153; August 10, 2020) and 

will be removed using a vibratory 

hammer at the end of the project under 

this LOA (See Table 6). Unless stated 

otherwise, all of the work described 

below will be conducted as part of the 

proposed LOA. 

Additional temporary work trestles 

will support construction of the 

permanent westbound North TrestleBridge in the shallow water near the 

North Island. These work trestles will be 

the same or similar to the North Shore 

Work Trestle, steel structures founded 

on 36-inch diameter steel pipe piles 

with 30 to 40 feet spans sized to 

accommodate a 300-ton crane. 

Approximately 182 36-inch steel piles 

will be installed to support these trestles 

using a combination of vibratory and 

impact hammers except along the 

shoreline where drilling with a DTH 

hammer may be needed to install piles 

through the armor stone. 

Once that portion of the permanent 

eastbound and westbound North 

Trestle-Bridge is complete, the 

temporary pile foundations will be 

removed using a vibratory hammer and 

the work trestle reused for similar 

purposes at a different location on the 

project (e.g., Willoughby Bay Work 

Trestles). 

Jump Trestles for Bridge Construction 

at the North Trestle—Jump Trestles are 

temporary heavy duty platforms used to 

support cranes and other equipment, 

will be used the North Trestle for 

constructing trestle bridges. Jump 

trestles are built with a maximum of 

three spans which are progressively 

removed and reinstalled one span at a 

time, moving forward with the 

construction of the adjacent structure. 

Each span is supported by six (6) 

temporary 36-inch steel pipe piles. The 

steel pipe piles will be installed, 

removed, and reinstalled as the spans 

move forward using a combination of 

vibratory and impact hammers for 

installation except along the shoreline 

where drilling with a DTH hammer may 

be needed to install piles through the 

armor stone and vibratory hammers will 

be used for removal. Approximately 270 

individual pile installations and 270 

removals will be needed to support the 

Jump Trestle movement for construction 

of the permanent westbound North 

Trestle-Bridge. 

Templates and Permanent Piles at the 

North Trestle—Temporary template 

piles will be used to guide installation 

of the permanent concrete piles used to 

support the new North Trestle-Bridge 

(Table 7). The templates will be 

supported by four temporary steel piles 

up to 36-inch in diameter, generally one 

at each corner of the template. A twotier template will be used to account for 

the possible batter of the permanent 

piles. Each template will allow 

installation of multiple permanent 

concrete piles. A vibratory hammer will 

be used to install and remove the 

temporary 36-inch steel piles supporting 

the template. 

Five hundred and sixty-two (562) 

permanent 54-inch concrete cylinder 

piles will be installed using an impact 

hammer and will remain in place at the 

end of construction. Pre-drilling will be 

done in the open without the use of a 

casing. 

The drill, drill steel, and auger would 

be in leads and either attached to the 

pile leads or used independently and 

indexed to the template to resist 

rotation. The auger is anticipated to be 

54-inch in diameter and 10 feet or less 

in height. 

In areas containing rock obstructions, 

a casing will be advanced prior to 

installation of the permanent North 

Trestle piles. The DTH hammer will 

advance a 60-inch (outer diameter) steel 

pipe pile casing before installation of 

the 54-inch concrete cylinder pile. 

Approximately 15 60-inch steel pipe 

casings may be required. The 60-inch 

steel pipe casings will be left in place 

and cut to an appropriate length to 

accommodate final island construction. 

Demolition Trestle at the North 

Trestle—The North Trestle Demolition 

Trestle will consist of a series of jump 

trestles, similar to or the same as that 

used to construct the permanent 

westbound North Trestle-Bridge. The 

jump trestles will be located in the 

shallow water near the North Shore and 

will be installed, removed, and 

reinstalled as demolition of the existing 

structures moves from the shoreline 

towards deeper water. Each jump trestle 

used for demolition will be 45 feet wide 

and approximately 1,200 feet long. Each 

jump trestle span will be supported by 

temporary 36-inch steel pipe piles. 

Approximately 344 individual pile 

installations and 344 removals will be 

needed to support the jump trestle 

movements using a combination of 

vibratory and impact hammers for 

installation except along the shoreline 

where a DTH hammer may be needed to 

install piles through the armor stone 

and vibratory hammers will be used for 

removal. 

Moorings at the North Shore Work 

Trestle—Mooring dolphins that were 

installed under the existing IHA (85 FR 

48153; August 10, 2020) at the southern 

end and along the outside edge of the 

North Shore Work Trestle will be 

removed as part of the LOA. Each 

dolphin consists of three 24-inch steel 

piles (Table 6). An additional thirteen 


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(13) 42-inch steel pipe piles were 

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 24-inch steel pipe piles and 

42-inch steel pipe piles will be removed 

using a vibratory hammer. 

Sheet Piles at the North Shore 

Abutment—Approximately 187 

temporary panels of steel sheet piles 

(AZ–700–19) will be installed using a 

vibratory hammer at the North Shore 

shoreline to support excavation and 

construction of the North Shore 

Abutment. Most of this work is planned 

to be done at lower tides so that inwater work is minimized. However, 

some installation work below the tidal 

elevations (in-water) can be expected. 

Sheet piles will be removed using a 

vibratory hammer. 

Segment 2a—Tunnel 

This segment includes new bored 

tunnels, the tunnel approach structures, 

buildings, the North Island 

improvements for tunnel facilities, and 

South Island improvements. This 

segment is located in Construction Area 

3 as shown in Figure 1. 

Moorings at the North Island 

Expansion—Eighty (80) temporary 

moorings were installed along the 

perimeter of the North Island Expansion 

(North and South) under the existing 

IHA (HRCP 2020). All moorings will be 

removed using a vibratory hammer or 

cut to approximately 3 feet below the 

mudline. 

Hampton Creek Approach Channel 

Marker at the North Island—An existing 

pile-mounted (Aid to Navigation) 

channel marker at the entrance to the 

Hampton Creek Approach Channel will 

be removed and relocated to allow 

expansion of the North Island. It will be 

removed using a vibratory hammer and 

a new permanent pile (36-inch steel 

pile) will be installed using a vibratory 

hammer. 

Steel sheet piles will be installed as 

part of the North Island Expansion and 

at the shoreline of the North Island 

(Attachment 1, Figure 9) to support 

excavation and construction of the 

North Island Abutments and Expansion. 

Approximately 54 panels of sheet pile 

will be installed using a vibratory 

hammer around the perimeter of the 

North Island Expansion to support 

dredge and replacement of native soft 

soils. An additional 122 sheet pile 

panels will be installed around the 

perimeter of the North Island Expansion 

to support construction of the abutment 

and tunnel approach structure. 

Approximately 128 panels of sheet 

pile will be installed at the North Island 

shoreline to support excavation and 

construction of the North Island 

Abutment. Most of this work is expected 

to be done at lower tides so that inwater work is minimized. However, 

some sheet pile installation work below 

the tidal elevations (in-water) can be 

expected. All sheet piles will be 

removed using a vibratory hammer. 

TBM Platform at the South Island— 

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 installation of the TBM platform 

will occur under the existing IHA 

(HRCP 2020). 

The TBM Platform is a steel structure 

erected on 216 36-inch diameter steel 

piles, with an overall area of 

approximately 0.70 acre (approximately 

377 feet x 81 feet). The TBM Platform 

piles will be removed using a vibratory 

hammer or cut to approximately 3 feet 

below the mudline at the conclusion of 

the project. 

Conveyor Trestle at the South 

Island—Tunnel boring spoils and other 

related materials will be moved between 

the South Island and barges via a 

conveyor belt and other equipment 

inside the 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 will be erected on 84 

36-inch diameter steel piles. Installation 

of the Conveyor Trestle will occur under 

the existing IHA (85 FR 48153; August 

10, 2020). At the conclusion of the 

project, the Conveyor Trestle piles will 

be removed using a vibratory hammer or 

cut to approximately 3 feet below the 

mudline. 

Settlement Reduction Piles and Deep 

Foundation Piles at the South Island— 

Existing geotechnical conditions at the 

planned South Island Expansion will 

require additional considerations to 

reduce island settlement and support 

roadway construction. Therefore, 

approximately 394 24-inch steel pipe 

settlement reduction piles and 507 30- 

inch concrete-filled steel pipe deep 

foundation piles will be installed at the 

South Island Expansion to address these 

geotechnical conditions. The settlement 

reduction piles and the deep foundation 

piles will be installed using vibratory 

and impact hammers. Furthermore, the 

use of drilling with a DTH hammer may 

be needed to install the deep foundation 

piles through the armor stone. 

Temporary templates (Table 7) will be 

supported by four temporary steel pipe 

piles up to 36-inch in diameter that will 

be spudded in place and used to align 

the piles during installation. Steel sheet 

piles will be installed to partially 

enclose the deep foundation piles as 

installation progresses north to south 

along the island expansion area. For 

steel pipe piles in water depths greater 

than 20 feet, a bubble curtain will be 

used for pile installation to reduce 

hydroacoustic impacts caused by the 

impact hammer. A portion of the 

settlement reduction piles and deep 

foundation piles will be installed using 

a bubble curtain. See Mitigation for 

additional detail. 

Moorings at the South Island— 

Temporary moorings will be installed 

along the perimeter of the South Island 

Expansion to support the construction 

of the island expansion. Twenty-five 

(25) 42-inch 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 and eventually removed using 

a vibratory hammer. 

Sheet Piles at the South Island 

Expansion and Abutment—Steel sheet 

piles will be installed as part of the 

South Island Expansion and at the 

shoreline of the South Island to support 

excavation and construction of the 

South Island Abutment. Approximately 

152 panels of AZ–700–26 sheet pile will 

be installed around the perimeter of the 

South Island Expansion deep 

foundation piles using a vibratory 

hammer as pile installation progresses 

to support backfilling. 

In addition, approximately 226 panels 

of AZ–700–26 temporary steel sheet pile 

will be installed around the perimeter of 

the South Island Expansion to support 

dredge and replacement of native soft 

soils. Temporary steel sheet piles will 

be installed using a vibratory hammer 

and will be removed using a vibratory 

hammer after completion of dredging/ 

replacement works. 

Approximately 70 panels of AZ–700– 

19 sheet pile will be installed at the 

South Island shoreline to support 

excavation and construction of the 

abutment and tunnel approach structure 

at the South Island. Similar to the North 

Shore Abutment work, most of this 

work is expected to be done at lower 

tides so that in-water work is 

minimized. However, some sheet pile 

installation work below the tidal 

elevations (in-water) can be expected. 

All sheet piles will be removed using a 

vibratory hammer. 

Segment 3a—South Trestle-Bridge 

This segment 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 is 


tkelley on DSKBCP9HB2PROD with PROPOSALS2
1594 Federal Register / Vol. 86, No. 5 / Friday, January 8, 2021 / Proposed Rules 

located in Construction Area 2 as shown 

in Figure 1. 

Moorings at the South Trestle— 

Temporary moorings will be installed in 

the area of the South Trestle to support 

the construction of temporary work 

trestles and permanent trestle bridges. 

The installation of the moorings at the 

South Trestle will be performed under 

the existing IHA (HRCP 2020). The 

temporary moorings will be removed at 

the conclusion of the project using a 

vibratory hammer. 

Temporary Work Trestles for Bridge 

Construction at the South Trestle— 

Several temporary work trestles will 

support construction of the temporary 

bridges used for maintaining traffic at 

the South Trestle during construction 

(i.e., temporary MOT bridges) and will 

serve as temporary docks for delivery of 

deck elements and other materials. The 

South Trestle Work Trestles will consist 

of two separate structures at the South 

Island shoreline (South Island South 1 

and 2) and a third structure at the South 

Shore or Norfolk shoreline. 

The temporary South Trestle Work 

Trestle at South Island South 1 is a steel 

structure approximately 504 feet long 

and 44 feet wide, founded on 72 36-inch 

diameter steel piles with 30 to 40 feet 

spans sized to accommodate a 300-ton 

crane. Once the permanent roadway is 

complete, the temporary MOT Bridge 

will be removed as well as the South 

Island South 1 Work Trestle, including 

the temporary pile foundations and 

mooring piles. They will be removed via 

vibratory hammer and the work trestle 

will be reused for similar purposes at a 

different project location. 

The temporary South Trestle Work 

Trestle at South Island South 2 is a steel 

structure approximately 634 feet long 

and 54 feet wide, founded on 90 36-inch 

diameter steel piles with 30 to 40 feet 

spans sized to accommodate a 300-ton 

crane. The pile foundations will be 

removed using a vibratory hammer once 

the permanent roadway is complete. 

The temporary South Trestle Work 

Trestle at the South Shore or Norfolk 

shoreline will be similar to that used 

elsewhere on the project. The work 

trestle will be approximately 500 feet 

long and 66 feet wide with four 30 feet 

wide finger piers. The finger piers will 

consist of 94 36-inch diameter steel 

piles installed using a vibratory 

hammer. 

Temporary steel pile foundations for 

each of the work trestles will be 

installed using vibratory and impact 

hammers. A bubble curtain will be used 

during installation of steel pipe piles in 

water depths greater than 20 feet. Some 

areas near the shores and islands will 

require the use of drilling with a DTH 

hammer to install the temporary piles. 

The South Trestle Work Trestle pile 

foundations will be removed using a 

vibratory hammer. 

Templates and Permanent Piles at the 

South Trestle—Temporary template 

piles (Table 7) will be used to guide 

installation of the permanent concrete 

piles used to support the new South 

Trestle-Bridge. The templates will use 

four temporary steel piles up to 36-inch 

in diameter as supports, generally one at 

each corner of the template. A two-tier 

template will be used to account for the 

possible batter of the piles. Each 

template will allow installation of 

multiple permanent concrete piles. A 

vibratory hammer will be used to install 

and remove the temporary 36-inch steel 

piles supporting the template. 

Eight hundred and ten (810) 

permanent 54-inch concrete cylinder 

piles will be installed using an impact 

hammer and will remain in place at the 

end of construction. Pre-drilling will be 

done in the open without the use of a 

casing. The drill, drill steel, and drill 

auger would be in leads and either 

attached to the pile leads or used 

independently and indexed to the 

template to resist rotation. The drill 

auger is anticipated to be 54-inch in 

diameter and 10-feet less in height. It is 

expected that the drill, drill steel, and 

drill auger would have almost no impact 

on noise levels. 

In areas where there may be rock 

obstructions, such as at the toe of the 

existing South Island slope, a casing 

will be advanced prior to installation of 

the permanent South Trestle piles. The 

DTH hammer will advance a 60-inch 

(outer diameter) steel pipe pile casing 

before installation of the 54-inch 

concrete cylinder pile. Approximately 

65 60-inch steel pipe casings may be 

required. The 60-inch steel pipe casings 

will be left in place and cut to an 

appropriate length to accommodate final 

island construction. 

Jump Trestle for Bridge Construction 

at the South Trestle—Temporary jump 

trestles will be used for constructing 

trestle bridges (both new permanent and 

temporary MOT bridges) at the South 

Trestle. A combination of jump trestles 

and working from the existing trestles 

will be used to build the new trestle 

bridges. 

The 36-inch steel pipe piles will be 

installed, removed, and reinstalled as 

the spans move forward using a 

combination of vibratory and impact 

hammers for installation except along 

the shoreline where drilling with a DTH 

hammer may be needed to install piles 

through the armor stone. Vibratory 

hammers will be used for removal. A 

bubble curtain will be used for 

installation of steel pipe piles in water 

depths greater than 20 feet. 

Approximately 420 individual pile 

installations and 420 removals will be 

needed to support the jump trestle 

movement for construction of the 

permanent westbound South TrestleBridge. 

Temporary MOT Trestles at the South 

Trestle—Two temporary MOT Trestle 

bridges at the South Trestle will be used 

to phase construction and carry traffic 

prior to completion of the new 

structures. The eastbound traffic will be 

shifted on the new MOT Trestle to allow 

for a partial demolition of the existing 

eastbound bridge-trestle. Once the 

partial demolition is completed, the 

new eastbound connection to the eightlane trestle will be built with the 

support of a jump trestle and eastbound 

traffic will be shifted on it. A temporary 

MOT Trestle will be built from South 

Island next to the existing westbound 

trestle. The westbound traffic will be 

shifted on the new MOT Trestle to allow 

for a partial demolition of the existing 

westbound bridge-trestle. A portion of 

the existing eastbound bridge-trestle 

will also be demolished to allow the 

new connection between the eight-lane 

structure and the new westbound 

bridge-trestle. The temporary MOT 

Trestle at the South Trestle will be a 

steel structure erected on 218 36-inch 

steel pipe piles that will be installed 

using a combination of vibratory and 

impact hammers except along the 

shoreline where drilling with a DTH 

hammer may be needed to install piles 

through the armor stone. A bubble 

curtain will be used for installation of 

steel pipe piles in water depths greater 

than 20 feet. Pile foundations will be 

removed using a vibratory hammer. 

Thirty 42-inch steel pipe pile casings 

will be installed using a vibratory 

hammer in areas where the MOT trestle 

is in the footprint of the South Island 

Expansion. The 42-inch steel pipe pile 

casings will be left in place and cut to 

an appropriate length to accommodate 

final island construction. 

Demolition Trestle at the South 

Trestle—The South Trestle Demolition 

Trestle will be similar to the work 

trestles previously described (e.g. 

Demolition Trestle at the North Trestle). 

Located at the South Shore, the South 

Trestle Demolition Trestle will be used 

to access the shallow water at the South 

Shore and support equipment used to 

remove the existing trestle structure. 

Approximately 72 36-inch steel pipe 

piles will be installed with a 

combination of vibratory and impact 

hammers. Some areas near the shores 

and islands will require the use of a 

DTH hammer to install the temporary 


tkelley on DSKBCP9HB2PROD with PROPOSALS2
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piles. At the conclusion of the project, 

the South Trestle Demolition Trestle 

will be removed using a vibratory 

hammer. 

Segment 3C—Willoughby Bay TrestleBridges 

This segment 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 is 

located in Construction Area 2 as shown 

in Figure 1. 

Moorings at Willoughby Bay— 

Temporary moorings will be installed in 

Willoughby Bay to support the 

construction of temporary work trestles 

and permanent trestle bridges, and to 

provide a safe haven (harbor of safe 

refuge) for vessels in the event of severe 

weather. Moorings will consist of six 

dolphins—each consisting of three 24- 

inch steel piles—and 50 42-inch steel 

pipe piles. The mooring dolphin piles 

and the single mooring point piles will 

be installed under the existing IHA (85 

FR 48153; August 10, 2020). 

An additional 40 42-inch steel pipe 

piles will be installed in Willoughby 

Bay to complete the safe haven (50 42- 

inch piles will be installed under the 

existing IHA; HRCP 2020). The 

moorings will be configured as two 

2,000-feet long lines with a 42-inch 

mooring pile every 80-feet. The piles 

will be installed using a vibratory 

hammer and removed at the conclusion 

of the project using a vibratory hammer. 

Temporary Work Trestles for Bridge 

Construction at Willoughby Bay—The 

existing Willoughby Bay Bridge 

structure will be modified by widening 

the two existing structures to the 

outside in both directions to 

accommodate new travel lanes, 

shoulders, and new sound walls. This 

will require installation of two to three 

additional piles at each pier location on 

the outside of both eastbound and 

westbound structures. Two temporary 

work trestles, each approximately 500 

feet long and 45 feet wide, will be 

installed along the outside edge of the 

existing eastbound structure to provide 

access in the shallow water area near 

both shorelines. Approximately 212 36- 

inch steel pipe piles will be installed 

using a combination of vibratory and 

impact hammers to support the 

temporary work trestles. The temporary 

steel piles will be removed using a 

vibratory hammer. 

Jump Trestle for Bridge Construction 

at Willoughby Bay—A combination of 

jump trestles and working from the 

existing trestles will be used to 

construct the widening of the existing 

Willoughby Bay westbound roadway. 

Similar to other locations (e.g., Jump 

Trestle at the North Trestle see Section), 

the jump trestle will be supported by 

temporary 36-inch steel pipe pile 

foundations that will be installed, 

removed, and reinstalled as the spans 

move forward using a combination of 

vibratory and impact hammers for 

installation and vibratory hammers for 

removal. Approximately 544 individual 

pile installations and 544 removals will 

be needed to support the jump trestle 

movement across Willoughby Bay. 

Templates and Permanent Piles at 

Willoughby Bay—Temporary template 

piles (Table 7) will be used to guide 

installation of the permanent concrete 

piles used to support widening of the 

eastbound and westbound Willoughby 

Bay roadway. The templates will be 

supported by four temporary steel piles 

up to 36-inch in diameter with one at 

each corner of the template. 

A vibratory hammer will be used to 

install and remove the temporary 36- 

inch steel piles supporting the template. 

Some areas near the shorelines may 

require the use of a DTH hammer to 

install the templates (Table 7). 

Five hundred and four (504) 24-inch 

concrete square permanent piles will be 

installed using an impact hammer and 

will remain in place at the end of 

construction. Where geotechnical 

conditions require, the permanent piles 

may also be installed via jetting. Where 

jetting is required, an outer steel pipe 

pile casing (up to 42-inch in diameter) 

may be installed using a vibratory 

hammer before installation of the 

concrete pile. Approximately 300 

casings (60 percent of the 504 concrete 

piles) will be installed prior to installing 

the concrete piles. The casing will be 

driven and the sediment and sand 

removed from the casing prior to 

installing the permanent pile. The 

casing will be removed using a vibratory 

hammer. 

Segment 3b—Willoughby Spit Laydown 

Area 

This segment includes the 

Willoughby Spit Laydown Area which 

is a temporary construction staging and 

laydown area that will include the 

installation and removal of temporary 

piers. This segment is located in 

Construction Area 4 as shown in Figure 

1. 

Temporary Docks on Spuds and Piles 

at the Willoughby Spit Laydown Area— 

HRCP has been granted use of property 

on Willoughby Spit next to the South 

Trestle-Bridge to be used for laydown 

areas and as a base for marine 

operations. Two temporary piers will be 

constructed to allow barge access: One 

will be a fixed pier on 44 36-inch steel 

pipe piles, and the other will be a 

floating dock on 8 36-inch steel pipe 

(spuds) piles. Piles will be installed 

using vibratory and impact hammers, as 

well as a pile template. The pile 

template will be supported by four 

temporary steel piles up to 36-inch in 

diameter (Table 7). The temporary piers, 

including the steel pile foundations, 

will be removed upon completion of the 

Project via vibratory hammer. 

Temporary Finger Piers on Timber 

Piles at the Willoughby Spit Laydown 

Area—The existing bulkheads and piers 

located on the inside of Willoughby Spit 

will be repaired to provide access for 

crew boats and similar-sized vessels. 

Three timber piers will replace the 

existing piers and will be constructed 

using 36 16-inch CCA timber piles, each 

pier consisting of 12 16-inch CCA 

timber piles. The piles will be installed 

using a vibratory hammer. Any existing 

timber piers will be pulled out of place. 

HRCP plans to employ five methods 

of pile installation including vibratory 

hammer, impact hammer, pre-drilling, 

jetting, and use of DTH hammers. More 

than one installation method could be 

used within a day and at each location 

and multiple piles could be installed 

and/or removed concurrently. Steel pipe 

piles will most likely be installed using 

a combination of vibratory (ICE 416L or 

similar) and impact hammers (S35 or 

similar). Approximately 80 percent of 

the time steel pipe piles will be 

installed using a vibratory hammer 

while an impact hammer will be used 

approximately 20 percent of the time. 

Most piles will be advanced using 

vibratory methods and then impact 

driven to final tip elevation. 

Temporary steel pile templates will be 

used to set permanent piles. Templates 

will be positioned and held in place 

using spuds or steel pipe piles, up to 36- 

inch diameter with one at each corner 

of the template. Template piles are 

temporary and generally do not bear 

significant vertical loads, therefore 

installation (i.e., driving) and removal of 

template piles requires minimal driving 

time, estimated at approximately 5 

minutes per spud (see Table 7). 

Permanent concrete piles will be 

installed using an impact hammer only, 

although permanent concrete piles may 

also be installed via jetting at 

Willoughby Bay. During jetting, highpressure water is sprayed out of the 

bottom of the pile to help penetrate 

dense sand layers and allow pile driving 

with lower hammer impact energies. 

Jetting will only be conducted at depth 

once sufficient resistance to pile 

installation has been met. Where jetting 

is required, an outer steel pipe pile 

casing may be installed before 


tkelley on DSKBCP9HB2PROD with PROPOSALS2
1596 Federal Register / Vol. 86, No. 5 / Friday, January 8, 2021 / Proposed Rules 

installation of the square concrete piles 

at Willoughby Bay. Casings will be 

driven using a vibratory hammer and 

the sediment and sand removed from 

the casing prior to driving the 

permanent concrete pile. HRCP 

assumed, and NMFS agrees, that jetting 

will be quieter than vibratory 

installation of the same pile size, but 

data for this activity are limited; 

therefore, sound source levels (SSLs) for 

vibratory installation were applied to 

jetting. 

Pre-drilling will be performed on the 

54-inch concrete cylinder permanent 

piles without the use of a casing in the 

open. The drill, drill steel, and auger 

will be in leads and either attached to 

the pile leads or used independently 

and indexed to the template to resist 

rotation. A 54-inch diameter auger 10- 

feet or less in height is expected to be 

employed. Pre-drilling will be 

conducted to loosen soils directly 

underneath the pile to maximize pile 

advancement before the drive and 

shorten the length of driving time. Predrilling may reduce driving times by as 

much as 50 percent and pre-drilling 

depth is expected to be less than half 

the pile length. HRCP may drill to 

within 3–4 diameters above the final tip 

elevation in cases of dense sand. HRCP 

assumed and NMFS agrees that use of 

the drill, drill turntable, drill steel, drill 

auger, and drill bit will not result in 

harassment. These devices have low 

source levels and, therefore, low signalto-noise ratios. The signal 

characteristics (continuous noise) would 

be occurring in a relatively noisy coastal 

environment where low-level 

continuous noise is common. Therefore, 

they would be unlikely to provoke a 

reaction consistent with what we would 

consider to be harassment. Therefore, 

harassment zone sizes were not 

estimated for these activities. These 

devices simply rotate in the sediments 

and do not displace them without 

creating a hole. No pile is installed 

during pre-drilling, and much less 

energy is expended than during pile 

installation. The equipment and nature 

of the act of pre-drilling in soils produce 

minimal noise and the pre-drilling will 

significantly reduce the driving time 

which in turn reduces the total noise 

levels. 

The pile installation methods used 

will depend on sediment depth and 

conditions at each pile location. Table 2 

through Table 7 provides additional 

information on the pile driving 

operation including estimated pile 

driving times. Note that the sum of the 

days of pile installation and removal is 

greater than the anticipated number of 

days because more than one pile 

installation method will be used within 

a day and at each location. The overall 

number of anticipated days of pile 

installation and removal is 312 per year, 

based on a six-day work week for years 

1–4. Year 5 will require an estimated 

181 days of in-water work. It is possible 

that installation and removal numbers 

might shift from one month to another 

depending on schedule constraints. 

HRCP will employ a bubble curtain 

when installing steel pipe piles in water 

depths greater than 20 feet to minimize 

hydroacoustic impacts caused by the 

impact hammer. Bubble curtains will be 

used at the South Island to install a 

portion of the permanent settlement 

reduction piles and deep foundation 

piles and at the South Trestle to install 

a portion of the Temporary MOT 

Trestle, Jump Trestle, and Work Trestle. 

Before installing steel pipe piles near 

shorelines protected with rock armor 

and/or rip rap (e.g., South Island 

shoreline; North Shore shoreline) the 

rock armoring that protects the 

shoreline will need to be temporarily 

shifted 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. Any rock 

armor stone and/or rip rap that has been 

moved will be reinstalled near its 

original location following the 

completion of pile installation. 

DTH pile installation uses both rotary 

and percussion-type drill devices and 

will be used frequently. The device 

consists of a drill bit that drills through 

stone using both rotary and pulse 

impact mechanisms. This breaks up the 

stone 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 and will be directed 

through a pipe to a designated location 

for waste. 

Piles may be also be installed without 

moving the armor stone by first drilling 

through the stone with a DTH hammer. 

It is estimated that drilling with a DTH 

hammer will be used for approximately 

1 to 2 hours per pile, when necessary. 

It is anticipated that approximately 7 

percent of the North Shore Work Trestle 

piles, 4 percent of the North Trestle 

Jump Trestle piles, 7 percent of the 

North Trestle Demolition Trestle piles, 

100 percent of the North Trestle 

Casings, 14 percent of the South Trestle 

Work Trestle piles, 6 percent of the 

South Trestle Jump Trestle piles, 10 

percent of the South Trestle Temporary 

MOT Trestle piles, 17 percent of the 

South Trestle Demolition Trestle piles, 

100 percent of the South Trestle 

Casings, and 10 percent of the South 

Island deep foundation piles may 

require installation with a DTH hammer 

(See Table 2 through Table 6). 

Temporary steel sheet piles and steel 

pipe piles will be removed using a 

vibratory hammer or cut to 

approximately 3 feet below the mudline. 

Temporary concrete piles will only be 

removed by cutting to approximately 3 

feet below the mudline. 

Table 2 through 6 below show the 

number and types of piles planned for 

installation and removal each year by 

component and segment while Table 7 

shows the total number of template 

piles over five years by location. 

TABLE 2—NUMBERS AND TYPES OF PILES TO BE INSTALLED AND REMOVED DURING LOA YEAR ONE FOR EACH HRBT 

PROJECT COMPONENT AND SEGMENT

Project 

component 

Pile size/ 

type and 

material 

Total 

number of 

piles 

to be 

installed 

Total 

number of 

piles to be 

removed 

Embedment 

length 

(feet) 

Number of 

piles 

down-thehole 

Average 

down-thehole 

duration 

per pile 

(minutes) 

Number of 

piles 

vibrated/ 

hammered 

Average 

vibratory 

duration 

per pile 

(minutes) 

Approximate 

number of 

impact strikes 

per pile 

Number of 

piles per 

day per 

hammer 

Estimated 

total number 

of hours of 

installation 

and removal 

Number of 

days of 

installation 

and removal 

North Trestle (Segment 1b) 

Permanent 

Piles.

54-inch Concrete Cylinder Pipe.

188 0 140 .................. .................. 188 .................. 2,100 1 376 188 

Casing .......... 60-inch Steel 

Pipe.

15 0 60 15 120 .................. .................. ...................... 3 30 5 

North Shore 

Abutment.

AZ 700–19 

Steel Sheet.

63 63 20 .................. .................. 126 30 ...................... 10 63 13 


tkelley on DSKBCP9HB2PROD with PROPOSALS2
Federal Register / Vol. 86, No. 5 / Friday, January 8, 2021 / Proposed Rules 1597 

TABLE 2—NUMBERS AND TYPES OF PILES TO BE INSTALLED AND REMOVED DURING LOA YEAR ONE FOR EACH HRBT 

PROJECT COMPONENT AND SEGMENT—Continued 

Project 

component 

Pile size/ 

type and 

material 

Total 

number of 

piles 

to be 

installed 

Total 

number of 

piles to be 

removed 

Embedment 

length 

(feet) 

Number of 

piles 

down-thehole 

Average 

down-thehole 

duration 

per pile 

(minutes) 

Number of 

piles 

vibrated/ 

hammered 

Average 

vibratory 

duration 

per pile 

(minutes) 

Approximate 

number of 

impact strikes 

per pile 

Number of 

piles per 

day per 

hammer 

Estimated 

total number 

of hours of 

installation 

and removal 

Number of 

days of 

installation 

and removal 

North Island (Segment 2a) 

Hampton 

Creek Approach 

Channel 

Marker.

Existing, 36- 

inch Steel 

Pipe.

1 1 .................... .................. .................. 1 50 ...................... 1 2 1 

North Island 

Expansion.

AZ 700–26 

Steel Sheet.

176 176 40 .................. .................. 352 30 ...................... 10 176 35 

Willoughby Bay (Segment 3c) 

Work Trestle 36-inch Steel 

Pipe.

212 0 100 .................. .................. 212 50 40 2 177 106 

Moorings 

(Safe 

Haven).

42-inch Steel 

Pipe.

40 0 60 .................. .................. 40 30 ...................... 6 20 7 

Permanent 

Piles.

24-inch Concrete 

Square 

Pipe.

402 0 140 .................. .................. 402 .................. 2,100 1 804 402 

Casing .......... 42-inch Steel 

Pipe.

240 240 60 .................. .................. 480 30 ...................... 6 160 80 

Willoughby Spit (Segment 3b) 

Dock on 

Spuds, 

Floating 

Dock.

36-inch Steel 

Pipe.

8 0 100 .................. .................. 8 50 40 3 7 3 

Dock on 

Piles, Fixed 

Pier.

36-inch Steel 

Pipe.

44 0 100 .................. .................. 44 50 40 3 37 15 

Finger Piers 

on Timber 

Piles.

16-inch CCA* 

Timber.

36 0 60 .................. .................. 36 30 ...................... 4 18 9 

South Trestle (Segment 3a) 

Work Trestle 36-inch Steel 

Pipe.

156 0 100 22 120 134 50 40 2 130 78 

Temporary 

MOT * 

Trestle.

36-inch Steel 

Pipe.

113 0 100 11 120 102 50 40 2 85 51 

Casing .......... 42-inch Steel 

Pipe.

30 0 60 .................. .................. 30 30 ...................... 6 15 5 

Permanent 

Piles.

54-inch Concrete Cylinder Pipe.

252 0 140 .................. .................. 252 .................. 2,100 1 504 252 

Casing .......... 60-inch Steel 

Pipe.

65 0 60 65 120 .................. .................. ...................... 3 130 22 

South Island (Segment 2a) 

Settlement 

Reduction 

Piles.

24-inch Steel 

Pipe.

24 0 85 .................. .................. 24 60 40 6 24 4 

Deep Foundation Piles.30-inch Steel 

Pipe, Concrete Filled.

82 0 85 8 120 74 60 40 6 82 14 

Moorings ....... 42-inch Steel 

Pipe.

25 0 60 .................. .................. 25 30 ...................... 6 13 4 

South Island 

Abutment.

AZ 700–19 

Steel Sheet.

12 0 20 .................. .................. 12 30 ...................... 10 6 2 

Total ...... ....................... 2,184 480 .................... .................. .................. .................. .................. ...................... .................. ........................ 1,296 

TABLE 3—NUMBERS AND TYPES OF PILES TO BE INSTALLED AND REMOVED DURING LOA YEAR TWO FOR EACH HRBT 

PROJECT COMPONENT AND SEGMENT

Project 

component 

Pile size/ 

type and 

material 

Total 

number of 

piles 

to be 

installed 

Total 

number of 

piles to be 

removed 

Embedment 

length 

(feet) 

Number of 

piles 

down-thehole 

Average 

down-thehole 

duration 

per pile 

(minutes) 

Number of 

piles 

vibrated/ 

hammered 

Average 

vibratory 

duration 

per pile 

(minutes) 

Approximate 

number of 

impact strikes 

per pile 

Number of 

piles per 

day per 

hammer 

Estimated 

total number 

of hours of 

installation 

and removal 

Number of 

days of 

installation 

and removal 

North Trestle (Segment 1b) 

North Shore 

Work Trestle.

36-inch Steel 

Pipe.

0 194 100 .................. .................. 194 50 40 3 162 65 

Work Trestle 36-inch Steel 

Pipe.

182 ...................... 100 12 120 170 50 40 2 152 91 

Jump Trestle 36-inch Steel 

Pipe.

42 38 100 3 120 77 50 40 2 65 39 


tkelley on DSKBCP9HB2PROD with PROPOSALS2
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TABLE 3—NUMBERS AND TYPES OF PILES TO BE INSTALLED AND REMOVED DURING LOA YEAR TWO FOR EACH HRBT 

PROJECT COMPONENT AND SEGMENT—Continued 

Project 

component 

Pile size/ 

type and 

material 

Total 

number of 

piles 

to be 

installed 

Total 

number of 

piles to be 

removed 

Embedment 

length 

(feet) 

Number of 

piles 

down-thehole 

Average 

down-thehole 

duration 

per pile 

(minutes) 

Number of 

piles 

vibrated/ 

hammered 

Average 

vibratory 

duration 

per pile 

(minutes) 

Approximate 

number of 

impact strikes 

per pile 

Number of 

piles per 

day per 

hammer 

Estimated 

total number 

of hours of 

installation 

and removal 

Number of 

days of 

installation 

and removal 

Permanent 

Piles.

54-inch, Concrete Cylinder Pipe.

102 0 140 .................. .................. 102 .................. 2,100 1 204 102 

North Island (Segment 2a) 

North Island 

Abutment.

AZ 700–19 

Steel Sheet.

96 0 20 .................. .................. 96 30 ...................... 10 48 10 

Willoughby 

Bay (Segment 3c).

Jump Trestle 36-inch Steel 

Pipe.

84 76 100 .................. .................. 160 50 40 2 134 80 

Work Trestle 36-inch Steel 

Pipe.

0 126 100 .................. .................. 126 50 ...................... 2 105 63 

Permanent 

Piles.

24-inch Concrete 

Square 

Pipe.

102 0 140 .................. .................. 102 .................. 2,100 1 204 102 

Casing .......... 42-inch Steel 

Pipe.

60 60 60 .................. .................. 120 30 ...................... 6 60 20 

South Trestle (Segment 3a) 

Work Trestle 36-inch Steel 

Pipe.

100 0 100 14 120 86 50 40 2 84 50 

Jump Trestle 36-inch Steel 

Pipe.

175 175 100 10 120 350 50 40 2 292 175 

Temporary 

MOT * 

Trestle.

36-inch Steel 

Pipe.

105 0 100 10 120 95 50 ...................... 2 80 48 

Permanent 

Piles.

54-inch Concrete Cylinder Pipe.

168 0 140 .................. .................. 168 .................. 2,100 1 336 168 

South Island (Segment 2a) 

Settlement 

Reduction 

Piles.

24-inch Steel 

Pipe, Steel.

370 0 85 .................. .................. 370 60 40 6 370 62 

Deep Foundation Piles.30-inch Steel 

Pipe, Concrete Filled.

425 0 85 42 120 383 60 40 6 425 71 

South Island 

Abutment.

AZ 700–19 

Steel Sheet.

12 24 20 .................. .................. 36 30 ...................... 10 18 4 

South Island 

Expansion.

AZ 700–26 

Steel Sheet.

378 378 70 .................. .................. 756 30 ...................... 10 189 76 

Total ...... ....................... 2,401 1,071 .................... .................. .................. .................. .................. ...................... .................. ........................ 1,226 

TABLE 4—NUMBERS AND TYPES OF PILES TO BE INSTALLED AND REMOVED DURING LOA YEAR THREE FOR EACH HRBT 

PROJECT COMPONENT AND SEGMENT

Project 

component 

Pile size/type 

and material 

Total 

number of 

piles to be 

installed 

Total number 

of piles to be 

removed 

Embedment 

length 

(feet) 

Number of 

piles 

down-thehole 

Average 

downthe-hole 

duration 

per pile 

(minutes) 

Number of 

piles 

vibrated/ 

hammered 

Average 

vibratory 

duration 

per pile 

(minutes) 

Approximate 

number of 

impact strikes 

per pile 

Number of 

piles per 

day per 

hammer 

Estimated 

total number 

of hours of 

installation 

and removal 

Number of 

days of 

installation 

and removal 

North Trestle (Segment 1b) 

Jump Trestle 36-inch Steel 

Pipe.

228 232 100 9 120 451 50 40 2 376 226 

Permanent 

Piles.

54-inch, Concrete Cylinder Pipe.

187 0 140 .................. .................. 187 .................. 2,100 1 374 187 

North Shore 

Abutment.

AZ 700–19 

Steel Sheet.

62 62 20 .................. .................. 124 30 ...................... 10 62 13 

North Island (Segment 2a) 

North Island 

Abutment.

AZ 700–19 

Steel Sheet.

32 128 20 .................. .................. 160 30 ...................... 10 80 16 

Willoughby Bay (Segment 3c) 

Jump Trestle 36-inch Steel 

Pipe.

460 468 100 .................. .................. 928 50 40 2 774 464 

Work Trestle 36-inch Steel 

Pipe.

0 86 100 .................. .................. 86 50 ...................... 2 72 43 

South Trestle (Segment 3a) 

Jump Trestle 36-inch Steel 

Pipe.

245 245 100 14 120 476 50 40 2 397 238 


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TABLE 4—NUMBERS AND TYPES OF PILES TO BE INSTALLED AND REMOVED DURING LOA YEAR THREE FOR EACH HRBT 

PROJECT COMPONENT AND SEGMENT—Continued 

Project 

component 

Pile size/type 

and material 

Total 

number of 

piles to be 

installed 

Total number 

of piles to be 

removed 

Embedment 

length 

(feet) 

Number of 

piles 

down-thehole 

Average 

downthe-hole 

duration 

per pile 

(minutes) 

Number of 

piles 

vibrated/ 

hammered 

Average 

vibratory 

duration 

per pile 

(minutes) 

Approximate 

number of 

impact strikes 

per pile 

Number of 

piles per 

day per 

hammer 

Estimated 

total number 

of hours of 

installation 

and removal 

Number of 

days of 

installation 

and removal 

Demolition 

Trestle.

36-inch Steel 

Pipe.

15 0 100 2 120 13 50 40 2 13 30 

Work Trestle 36-inch Steel 

Pipe.

0 182 100 .................. .................. 182 50 ...................... 2 152 91 

Temporary 

MOT * 

Trestle.

36-inch Steel 

Pipe.

0 110 100 .................. .................. 110 50 ...................... 2 92 55 

Permanent 

Piles.

54-inch Concrete Cylinder Pipe.

196 0 140 .................. .................. 196 .................. 2,100 1 392 196 

South Island (Segment 2a) 

South Island 

Abutment.

AZ 700–19 

Steel Sheet.

46 46 20 .................. .................. 92 30 ...................... 10 46 10 

Total ...... ....................... 1,471 1,559 .................... .................. .................. .................. .................. ...................... .................. ........................ 1,569 

TABLE 5—NUMBERS AND TYPES OF PILES TO BE INSTALLED AND REMOVED DURING LOA YEAR THREE FOR EACH HRBT 

PROJECT COMPONENT AND SEGMENT

Project 

component 

Pile size/type 

and material 

Total 

number of 

piles to be 

installed 

Total number 

of piles to be 

removed 

Embedment 

length 

(feet) 

Number of 

piles 

down-thehole 

Average 

downthe-hole 

duration 

per pile 

(minutes) 

Number of 

piles 

vibrated/ 

hammered 

Average 

vibratory 

duration 

per pile 

(minutes) 

Approximate 

number of 

impact strikes 

per pile 

Number of 

piles per 

day per 

hammer 

Estimated total 

number of 

hours of 

installation and 

removal 

Number of 

days of 

installation 

and removal 

North Trestle (Segment 1b) 

Demolition 

Trestle.

36-inch Steel 

Pipe.

344 172 100 24 120 492 50 40 2 410 246 

Permanent 

Piles.

54-inch, Concrete Cylinder Pipe.

85 0 140 .................. .................. 85 .................. 2,100 1 170 85 

North Shore 

Abutment.

AZ 700–19 

Steel Sheet.

62 62 20 .................. .................. 124 30 ...................... 10 62 13 

South Trestle (Segment 3a) 

Demolition 

Trestle.

36-inch Steel 

Pipe.

57 72 100 10 120 119 50 40 2 99 60 

Work Trestle 36-inch Steel 

Pipe.

0 74 100 .................. .................. 74 50 ...................... 2 62 37 

Temporary 

MOT * 

Trestle.

36-inch Steel 

Pipe.

0 108 100 .................. .................. 108 50 ...................... 2 90 54 

Permanent 

Piles.

54-inch Concrete Cylinder Pipe.

194 0 140 .................. .................. 194 .................. 2,100 1 388 194 

South Island (Segment 2a) 

TBM Platform 36-inch Steel 

Pipe.

0 216 140 .................. .................. 216 60 ...................... 2 216 108 

Conveyor 

Trestle.

36-inch Steel 

Pipe.

0 84 100 .................. .................. 84 50 ...................... 3 70 42 

Total ...... ....................... 742 788 .................... .................. .................. .................. .................. ...................... .................. ........................ 839 

TABLE 6—NUMBERS AND TYPES OF PILES TO BE INSTALLED AND REMOVED DURING LOA YEAR FIVE FOR EACH HRBT 

PROJECT COMPONENT AND SEGMENT

Project 

component 

Pile size/type 

and material 

Total 

number of 

piles to be 

installed 

Total number 

of piles to be 

removed 

Embedment 

length 

(feet) 

Number of 

piles 

down-thehole 

Average 

downthe-hole 

duration 

per pile 

(minutes) 

Number of 

piles 

vibrated/ 

hammered 

Average 

vibratory 

duration 

per pile 

(minutes) 

Approximate 

number of 

impact strikes 

per pile 

Number of 

piles per 

day per 

hammer 

Estimated total 

number of 

hours of 

installation and 

removal 

Number of 

days of 

installation 

and removal 

North Trestle (Segment 1b) 

Moorings ....... 42-inch Steel 

Pipe.

0 36 60 .................. .................. 36 30 ...................... 6 18 6 

Moorings ....... 24-inch Steel 

Pipe.

0 30 60 .................. .................. 30 30 ...................... 6 15 5 

Work Trestle 36-inch Steel 

Pipe.

0 182 100 .................. .................. 182 50 ...................... 2 152 91 

Demolition 

Trestle.

36-inch Steel 

Pipe.

0 172 100 .................. .................. 172 50 ...................... 2 144 86 


tkelley on DSKBCP9HB2PROD with PROPOSALS2
1600 Federal Register / Vol. 86, No. 5 / Friday, January 8, 2021 / Proposed Rules 

TABLE 6—NUMBERS AND TYPES OF PILES TO BE INSTALLED AND REMOVED DURING LOA YEAR FIVE FOR EACH HRBT 

PROJECT COMPONENT AND SEGMENT—Continued 

Project 

component 

Pile size/type 

and material 

Total number of 

piles to be 

installed 

Total number 

of piles to be 

removed 

Embedment length 

(feet) 

Number of piles down-the- hole 

Average 

downthe-hole 

duration 

per pile 

(minutes) 

Number of piles 

vibrated/ 

hammered 

Average 

vibratory 

duration 

per pile 

(minutes) 

Approximate 

number of 

impact strikes 

per pile 

Number of 

piles per 

day per 

hammer 

Estimated total number of 

hours of installation and removal 

Number of 

days of 

installation 

and removal 

North Island (Segment 2a) 

Moorings ....... 42-inch Steel 

Pipe.

0 80 60 .................. .................. 80 30 ...................... 6 40 14 

Willoughby Bay (Segment 3c) 

Moorings ....... 42-inch Steel 

Pipe.

0 50 60 .................. .................. 50 30 ...................... 6 25 9 

Moorings ....... 24-inch Steel 

Pipe.

0 18 60 .................. .................. 18 30 ...................... 6 9 3 

Moorings .......

(Safe Haven) 

42-inch Steel 

Pipe.

0 90 60 .................. .................. 90 30 ...................... 6 45 15 

Willoughby Spit (Segment 3b) 

Dock on 

Spuds, 

Floating 

Dock.

36-inch Steel 

Pipe.

0 8 100 .................. .................. 8 50 ...................... 3 7 3 

Dock on 

Piles, Fixed 

Pier.

36-inch Steel 

Pipe.

0 44 100 .................. .................. 44 50 ...................... 3 37 15 

Finger Piers 

on Timber 

Piles.

16-inch 

CCA *, Timber.

0 36 60 .................. .................. 36 30 ...................... 4 18 9 

South Trestle (Segment 3a) 

Moorings ....... 42-inch Steel 

Pipe.

0 41 60 .................. .................. 41 30 ...................... 6 21 7 

Moorings ....... 24-inch Steel 

Pipe.

0 18 60 .................. .................. 18 30 ...................... 6 9 3 

South Island (Segment 2a) 

Mooring ........ 42-inch Steel 

Pipe.

0 25 60 .................. .................. 25 30 ...................... 6 13 5 

Total ...... ....................... 0 830 .................... .................. .................. .................. .................. ...................... .................. ........................ 271 

TABLE 7—NUMBERS OF TEMPLATE PILES (UP TO 36-INCH STEEL PIPE PILES) TO BE INSTALLED AND REMOVED USING A

VIBRATORY HAMMER FOR THE HRBT PROJECT

Project component/location Pile size/type and material 

Estimated 

number of 

template piles 

to be installed 

Estimated 

number of 

template piles 

to be removed 

Average downthe-hole 

duration per pile 

(minutes) 

Average 

vibratory 

duration per 

template pile 

(minutes) 

Number of piles 

per day per 

component 

(install and 

removal) 

North Trestle Permanent Piles ...... 54-inch Concrete Cylinder Pipe .... 750 750 .......................... 5 8 

South Trestle Permanent Piles ..... 54-inch Concrete Cylinder Pipe .... 1080 1080 .......................... 5 8 

Willoughby Bay Permanent Piles .. 24-inch Concrete Square Pipe ...... 672 672 .......................... 5 8 

Willoughby Spit Fixed Pier * .......... 36-inch Steel Pipe ......................... 59 59 .......................... 5 16 

Willoughby Spit Floating Pier * ...... 36-inch Steel Pipe ......................... 11 11 .......................... 5 16 

South Island Deep Foundation 

Piles.

30-inch Steel Pipe, Concrete 

Filled.

676 676 120 5 16 

South Island Settlement Reduction 

Piles.

24-inch Steel Pipe ......................... 526 526 .......................... 5 16 

Estimated Total Template Pile 

Driving Actions.

....................................................... 3,774 3,774 .......................... .......................... ............................

Total number of Temporary Template Pile 

Driving action.

................................................... 7,584 

Proposed mitigation, monitoring, and 

reporting measures are described in 

detail later in this document (please see 

Proposed Mitigation and Proposed 

Monitoring and Reporting). 

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’ Stock 

Assessment Reports (SAR); https://

www.fisheries.noaa.gov/national/ 

marine-mammal-protection/marinemammal-stock-assessment-reportsregion and more general information 

about these species (e.g., physical and 

behavioral descriptions) may be found 


tkelley on DSKBCP9HB2PROD with PROPOSALS2
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on NMFS’ website (https://

www.fisheries.noaa.gov/find-species). 

Table 8 lists all species with expected 

potential for occurrence in the project 

area 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 (2020). PBR is defined by the 

MMPA as the maximum number of 

animals, not including natural 

mortalities, that may be removed from a 

marine mammal stock while allowing 

that stock to reach or maintain its 

optimum sustainable population (as 

described in NMFS’ SARs). While no 

mortality is anticipated or authorized 

here, PBR and annual serious injury and 

mortality from anthropogenic sources 

are included here as gross indicators of 

the status of the species and other 

threats. 

Marine mammal abundance estimates 

presented in this document represent 

the total number of individuals that 

make up a given stock or the total 

number estimated within a particular 

study or survey area. NMFS’s stock 

abundance estimates for most species 

represent the total estimate of 

individuals within the geographic area, 

if known, that comprises that stock. For 

some species, this geographic area may 

extend beyond U.S. waters. All managed 

stocks in this region are assessed in 

NMFS’s U.S. Atlantic and Gulf of 

Mexico SARs (e.g., Hayes et al., 2020). 

All values presented in Table 8 are the 

most recent available at the time of 

publication and are available in the 

2019 SARs (Hayes et al., 2020). 

TABLE 8—MARINE MAMMAL SPECIES LIKELY TO OCCUR NEAR THE PROJECT AREA

Common name Scientific name Stock 

ESA/ 

MMPA 

status; 

strategic 

(Y/N) 1

Stock 

abundance 

(CV, Nmin, most recent 

abundance 

survey) 2

PBR Annual 

M/SI 3

Order Cetartiodactyla—Cetacea—Superfamily Mysticeti (baleen whales) 

Family Balaenopteridae 

(rorquals): 

Humpback whale ................ Megaptera novaeangliae .......... Gulf of Maine ............................ –,–; N 1,396 (0; 1,380; see 

SAR).

22 12.15 

Superfamily Odontoceti (toothed whales, dolphins, and porpoises) 

Family Delphinidae: 

Bottlenose dolphin .............. Tursiops truncatus .................... Western North Atlantic (WNA) 

Coastal, Northern Migratory.

–,–; Y 6,639 (0.41; 4,759; 2011) 48 6.1–13.2 

WNA Coastal, Southern Migratory.–,–; Y 3,751 (0.06; 2,353; 2011) 23 0–14.3 

Northern North Carolina Estuarine System (NNCES).–,–; Y 823 (0.06; 782; 2013) ..... 7.8 0.8–18.2 

Family Phocoenidae (porpoises): 

Harbor porpoise .................. Phocoena phocoena ................. Gulf of Maine/Bay of Fundy ...... –, –; N 95,543 (0.31; 74,034; 

see SAR).

851 217 

Order Carnivora—Superfamily Pinnipedia 

Family Phocidae (earless seals): 

Harbor seal ......................... Phoca vitulina ........................... WNA .......................................... –; N 75,834 (0.15; 66,884, 

see SAR).

2,006 350 

Gray seal 4 .......................... Halichoerus grypus ................... WNA .......................................... –; N 27,131 (0.19, 23,158, 

see SAR).

1,359 5,410 

1Endangered 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-assessmentreports-region. CV is coefficient of variation; Nmin is the minimum estimate of stock abundance. In some cases, CV is not applicable. 3These 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. 4The NMFS stock abundance estimate applies to U.S. population only, however the actual stock abundance is approximately 451,431.

As indicated above, all five species 

(with seven managed stocks) in Table 8 

temporally and spatially co-occur with 

the activity to the degree that take is 

reasonably likely to occur, and we have 

proposed authorizing take. 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; McLellan 2011b, 2013; Mallette et 

al., 2016a, 2016b, 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 (November 

1–April 30) 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 


tkelley on DSKBCP9HB2PROD with PROPOSALS2
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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 near the project area, 

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 

(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), which is 

approximately 17 km from the project 

site, 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), but 

sightings in the project area are 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 known 

minke whale occurrences in the project 

area are due to strandings, NMFS is not 

proposing to authorize take of this 

species. 

Humpback Whale 

Humpback whales are distributed 

worldwide in all major oceans and most 

seas. Most humpback whale sightings 

are in nearshore and continental shelf 

waters; however, humpback whales 

frequently travel through deep oceanic 

waters during migration (Calambokidis 

et al., 2001; Clapham, P.J. and Mattila, 

D.K., 1990). Prior to 2016, humpback 

whales were listed under the ESA as an 

endangered species worldwide. 

Following a 2015 global status review 

(Bettridge et al., 2015), NMFS 

established 14 DPSs with different 

listing statuses (81 FR 62259; September 

8, 2016) pursuant to the ESA. 

Humpback whales in the project area 

are expected to be from the West Indies 

DPS, which consists of the whales 

whose breeding range includes the 

Atlantic margin of the Antilles from 

Cuba to northern Venezuela, and whose 

feeding range primarily includes the 

Gulf of Maine, eastern Canada, and 

western Greenland. The West Indies 

DPS was delisted in 2016. Bettridge et 

al. (2003) estimated the size of the West 

Indies DPS at 12,312 (95 percent CI 

8,688–15,954) whales in 2004–05, 

which is consistent with previous 

population estimates of approximately 

10,000–11,000 whales (Stevick et al., 

2003; Smith et al., 1999) and the 

increasing trend for the West Indies DPS 

(Bettridge et al., 2015). 

Although humpback whales are 

migratory between feeding areas and 

calving areas, individual variability in 

the timing of migrations may result in 

the presence of individuals in highlatitude areas throughout the year 

(Straley, 1990). Records of humpback 

whales off the U.S. mid-Atlantic coast 

(New Jersey to North Carolina) from 

January through March suggest these 

waters may represent a supplemental 

winter feeding ground used by juvenile 

and mature humpback whales of U.S. 

and Canadian North Atlantic stocks 

(LaBrecque et al., 2015). 

The immediate project area is not 

within normal humpback whale feeding 

or migration areas. They are most likely 

to occur near the mouth of the 

Chesapeake Bay and coastal waters of 

Virginia Beach between January and 

March; however, they could be found in 

the area year-round, based on shipboard 

sighting and stranding data (Barco and 

Swingle, 2014; Aschettino et al., 2015; 

2016; 2017; 2018). Photo-identification 

data support the repeated use of the 

mid-Atlantic region by individual 

humpback whales. Results of the vessel 

surveys show site fidelity in the survey 

area for some individuals and a high 

level of occurrence within shipping 

channels (Aschettino et al., 2015; 2016; 

2017; 2018). Nearshore surveys 

conducted in early 2015 reported 61 

individual humpback whale sightings, 

and 135 individual humpback whale 

sightings in late 2015 through May 2016 

(Aschettino et al., 2016). Subsequent 

surveys confirmed the occurrence of 

humpback whales in the nearshore 

survey area: 248 individuals were 

detected in 2016–2017 surveys 

(Aschettino et al., 2017), 32 individuals 

were detected in 2017–2018 surveys 

(Aschettino et al., 2018), and 80 

individuals were detected in 2019 

surveys (Aschettino et al., 2019). 

Sightings in the Hampton Roads area in 

the vicinity of Naval Station (NAVSTA) 

Norfolk were reported in nearshore 

surveys and through tracking of 

satellite-tagged whales in 2016, 2017 

and 2019. The numbers of whales 

detected, most of which were juveniles, 

reflect the varying level of survey effort 

and changes in survey objectives from 

year to year, and do not indicate 

abundance trends over time. Therefore, 

humpback whales could occur near the 

Project area and incidental take could 

result from exposure to underwater 

sounds during pile driving and removal. 

Bottlenose Dolphin 

Along the U.S. East Coast and 

northern Gulf of Mexico, there are 

currently 53 management stocks 

identified by NMFS in the western 

North Atlantic and Gulf of Mexico, 

including oceanic, coastal, and 

estuarine stocks (Hayes et al., 2020; 

Waring et al., 2016). 

The population structure of bottlenose 

dolphins off Virginia is complex. There 

are two morphologically and genetically 

distinct bottlenose dolphin 

morphotypes (distinguished by physical 

differences) described as coastal and 

offshore forms (Duffield et al., 1983; 

Duffield, 1986). The offshore form is 

larger in total length and skull length, 

and has wider nasal bones than the 

coastal form. Both inhabit waters in the 

western North Atlantic Ocean and Gulf 

of Mexico (Curry and Smith, 1997; 


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Mead and Potter, 1995) along the U.S. 

Atlantic coast. The coastal morphotype 

of bottlenose dolphin is continuously 

distributed along the Atlantic coast 

south of Long Island, New York, around 

the Florida peninsula, and along the 

Gulf of Mexico coast. This type typically 

occurs in waters less than 20 meters 

deep (Waring et al., 2015). The range of 

the offshore bottlenose dolphin includes 

waters beyond the continental slope 

(Kenney R. D., 1990), and offshore 

bottlenose dolphins may move between 

the Gulf of Mexico and the Atlantic 

(Wells et al., 1999). Bottlenose dolphins 

are the most abundant marine mammal 

along the Virginia coast and within the 

Chesapeake Bay, typically traveling in 

groups of 2 to 15 individuals, but 

occasionally in groups of over 100 

individuals (Engelhaupt et al., 2014; 

2015; 2016). 

Two coastal stocks are likely to be 

present in the HRBT project area: 

Western North Atlantic Northern 

Migratory Coastal stock and Western 

North Atlantic Southern Migratory 

Coastal stock. Additionally, the 

Northern North Carolina Estuarine 

System stock may occur in the project 

area. 

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. 2017). 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 (Patterson, Pers. Comm). 

Vessel surveys conducted along 

coastal and offshore transects from 

NAVSTA Norfolk to Virginia Beach in 

most months from August 2012 to 

August 2015 reported bottlenose 

dolphins throughout the survey area, 

including the vicinity of NAVSTA 

Norfolk (Engelhaupt et al., 2014; 2015; 

2016). The final results from this project 

confirmed earlier findings that 

bottlenose dolphins are common in the 

study area, with highest densities in the 

coastal waters in summer and fall 

months. However, bottlenose dolphins 

do not completely leave this area during 

colder months, with approximately 

200–300 individuals still present in 

winter and spring months (Engelhaupt 

et al., 2016). 

Harbor Porpoise 

Harbor porpoises inhabit cool 

temperate-to-subpolar waters, often 

where prey aggregations are 

concentrated (Watts and Gaskin, 1985). 

Thus, they are frequently found in 

shallow waters, most often near shore, 

but they sometimes move into deeper 

offshore waters. Harbor porpoises are 

rarely found in waters warmer than 63 

degrees Fahrenheit (17 degrees Celsius) 

(Read 1999) and closely follow the 

movements of their primary prey, 

Atlantic herring (Gaskin 1992). 

In the western North Atlantic, harbor 

porpoise range from Cumberland Sound 

on the east coast of Baffin Island, 

southeast along the eastern coast of 

Labrador to Newfoundland and the Gulf 

of St. Lawrence, then southwest to about 

34 degrees North on the coast of North 

Carolina (Waring et al., 2016). During 

winter (January to March), intermediate 

densities of harbor porpoises can be 

found in waters off New Jersey to North 

Carolina, and lower densities are found 

in waters off New York to New 

Brunswick, Canada (Waring et al., 

2016). Harbor porpoises sighted off the 

mid-Atlantic during winter include 

porpoises from other western North 

Atlantic populations (Rosel et al., 1999). 

There does not appear to be a 

temporally coordinated migration or a 

specific migratory route to and from the 

Bay of Fundy region (Waring et al., 

2016). During fall (October to December) 

and spring (April to June), harbor 

porpoises are widely dispersed from 

New Jersey to Maine, with lower 

densities farther north and south 

(LaBrecque et al., 2015). 

Based on stranding reports, passive 

acoustic recorders, and shipboard 

surveys, harbor porpoise occur in 

coastal waters primarily in winter and 

spring months, but there is little 

information on their presence in the 

Chesapeake Bay. They do not appear to 

be abundant in the HRBT project area in 

most years, but this is confounded by 

wide variations in stranding 

occurrences over the past decade. Since 

1999, stranding incidents have ranged 

widely from a high of 40 in 1999 to 2 

in 2011, 2012, and 2016 (Barco et al. 

2017). 

Harbor Seal 

The Western North Atlantic stock of 

harbor seals occurs in the HRBT project 

area. Harbor seal distribution along the 

U.S. Atlantic coast has shifted in recent 

years, with an increased number of seals 

reported from southern New England to 

the mid-Atlantic region (DiGiovanni et 

al., 2011; Hayes et al., 2017; Kenney R. 

D. 2019; Waring et al., 2016). Harbor 

seals are the most common seal in 

Virginia (Barco and Swingle 2014) and 

regular sightings of seals in Virginia 

have become a common occurrence in 

winter and early spring (Costidis et al., 

2019). Winter haulout sites for harbor 

seals have been documented in the 

Chesapeake Bay at the CBBT, on the 

Virginia Eastern Shore, and near Oregon 

Inlet, North Carolina (Waring et al., 

2016; Rees et al., 2016; Jones et al., 

2018). 

Harbor seals regularly haul out on 

rocks around the portal islands of the 

CBBT and on mud flats on the nearby 

southern tip of the Eastern Shore from 

December through April (Rees et al., 

2016; Jones et al., 2018). Seals captured 

in 2018 on the Eastern Shore and tagged 

with satellite-tracked tags that lasted 

from 2 to 5 months spent at least 60 

days in Virginia waters before departing 


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the area. All tagged seals returned 

regularly to the capture site while in 

Virginia waters, but individuals utilized 

offshore and Chesapeake Bay waters to 

different extents (Ampela et al., 2019). 

The area that was utilized most heavily 

was near the Eastern Shore capture site, 

but some seals ranged into the 

Chesapeake Bay. 

Gray Seal 

The Western North Atlantic stock of 

gray seal occurs in the project area. The 

western North Atlantic stock is centered 

in Canadian waters, including the Gulf 

of St. Lawrence and the Atlantic coasts 

of Nova Scotia, Newfoundland, and 

Labrador, Canada, and the northeast 

U.S. continental shelf (Hayes et al., 

2017). Gray seals range south into the 

northeastern United States, with 

strandings and sightings as far south as 

North Carolina (Hammill et al., 1998; 

Waring et al., 2004). Gray seal 

distribution along the U.S. Atlantic 

coast has shifted in recent years, with an 

increased number of seals reported in 

southern New England (DiGiovanni et 

al., 2011; Kenney R.D., 2019; Waring et 

al., 2016). Recent sightings included a 

gray seal in the lower Chesapeake Bay 

during the winter of 2014 to 2015 (Rees 

et al., 2016). Along the coast of the 

United States, gray seals are known to 

pup at three or more colonies in 

Massachusetts and Maine. 

Gray seals are uncommon in Virginia 

and in 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). 

Unusual Mortality Events 

An unusual mortality event (UME) is 

defined under Section 410(6) of the 

MMPA as a stranding that is 

unexpected; involves a significant dieoff of any marine mammal population; 

and demands immediate response. 

Currently, ongoing UME investigations 

are underway for pinnipeds along the 

Northeast coast, and humpback whales 

along the Atlantic coast. 

Northeast Pinniped UME 

Since July 2018, elevated numbers of 

harbor seal and gray seal mortalities 

have occurred across Maine, New 

Hampshire and Massachusetts. This 

event has been declared an UME. 

Additionally, seals showing clinical 

signs have been stranding as far south 

as Virginia, although not in elevated 

numbers; therefore, the UME 

investigation now encompasses all seal 

strandings from Maine to Virginia. 

Lastly, while take is not proposed for 

these species in this proposed rule, ice 

seals (harp and hooded seals) have also 

started stranding with clinical signs, 

again not in elevated numbers, and 

those two seal species have also been 

added to the UME investigation. 

Additional information is available at 

https://www.fisheries.noaa.gov/newengland-mid-atlantic/marine-lifedistress/2018-2020-pinniped-unusualmortality-event-along. 

Atlantic Humpback Whale UME 

Since January 2016, elevated 

humpback whale mortalities have 

occurred along the Atlantic coast from 

Maine through Florida. This event has 

been declared an UME. A portion of the 

whales have shown evidence of premortem vessel strike; however, this 

finding is not consistent across all 

whales examined, and additional 

research is needed. Additional 

information is available at https://

www.fisheries.noaa.gov/national/ 

marine-life-distress/2016-2020- 

humpback-whale-unusual-mortalityevent-along-atlantic-coast. 

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 lowfrequency 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 9. 

TABLE 9—MARINE MAMMAL HEARING GROUPS

[NMFS, 2018] 

Hearing group Generalized 

hearing range * 

Low-frequency (LF) cetaceans (baleen whales) ................................................................................................................. 7 Hz to 35 kHz. 

Mid-frequency (MF) cetaceans (dolphins, toothed whales, beaked whales, bottlenose whales) ...................................... 150 Hz to 160 kHz. 

High-frequency (HF) cetaceans (true porpoises, Kogia, river dolphins, cephalorhynchid, Lagenorhynchus cruciger & L. 

australis).

275 Hz to 160 kHz. 

Phocid pinnipeds (PW) (underwater) (true seals) .............................................................................................................. 50 Hz to 86 kHz. 

Otariid pinnipeds (OW) (underwater) (sea lions and fur seals) .......................................................................................... 60 Hz to 39 kHz. 

* 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). 


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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 

(Hemila ̈ et al., 2006; Kastelein et al., 

2009; Reichmuth and Holt, 2013). 

For more detail concerning these 

groups and associated frequency ranges, 

please see NMFS (2018) for a review of 

available information. Five marine 

mammal species (three cetacean and 

two phocid pinniped species) have the 

reasonable potential to co-occur with 

the proposed construction activities. 

Please refer to Table 8. Of the cetacean 

species that may be present, one is 

classified as a low-frequency cetacean 

(i.e., humpback whale) one is classified 

as a mid-frequency cetacean (i.e., 

bottlenose dolphin), and one is 

classified as a high-frequency cetacean 

(i.e., 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 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 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 

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 vibratory pile driving and pile 

removal, impact pile driving, jetting, 

and DTH pile installation. 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 one second), broadband, and 

consist of high peak sound pressure 

with rapid rise time and rapid decay 

(ANSI 1986; NIOSH 1998; ANSI 2005; 

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 

sounds produced by DTH hammers 

were previously thought to be 

continuous. However, recent sound 

source verification (SSV) monitoring has 

shown that DTH hammer can create 

sound that can be considered impulsive 

(Denes et al. 2019). Since sound from 

DTH activities has both impulsive and 

continuous components, NMFS 

characterizes sound from DTH pile 

installation as being impulsive when 

evaluating potential Level A harassment 

(i.e., injury) impacts and as being nonimpulsive when assessing potential 

Level B harassment (i.e. behavior) 

effects. 

The likely or possible impacts of 

HRCP’s proposed activity on marine 

mammals could involve both nonacoustic 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 driving and removal. 

Acoustic Impacts 

The introduction of anthropogenic 

noise into the aquatic environment from 

pile driving and removal is the primary 

means by which marine mammals may 

be harassed from HRCP’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). In 

general, exposure to pile driving 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). Exposure to 

anthropogenic noise can also lead to 

non-observable physiological responses 

such an increase in stress hormones. 

Additional noise in a marine mammal’s 

habitat can mask acoustic cues used by 


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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. nonimpulsive), 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. 

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 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 an animal uses sound within the 

frequency band of the signal; e.g., 

Kastelein et al. 2014), 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; 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)— 

TTS is 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 

(2015), 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 sound exposure level (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 noiseinduced 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). Installing piles 

requires a combination of impact pile 

driving and vibratory pile driving. For 

this project, these activities would not 

occur at the same time and there would 

be pauses in activities producing the 

sound during each day. Given these 

pauses and that many marine mammals 

are likely moving through the 

ensonified area and not remaining for 

extended periods of time, the potential 

for TS declines. 

Behavioral Harassment—Exposure to 

noise from pile driving and removal also 

has the potential to behaviorally disturb 

marine mammals. 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). 

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, 


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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. 

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 

curtains 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. 

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-pituitaryadrenal 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., 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), however distress is an 

unlikely result of this project based on 

observations of marine mammals during 

previous, similar projects in the area. 

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-tonoise 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. The project area contains 

numerous, naval, commercial, and 

recreational vessels; therefore, it is 

possible that background underwater 

sound levels in the area are elevated, 

meaning that continuous noise from 

sources such as vibratory pile driving 

would be less likely to cause disruption 

of behavioral patterns when detected. 

Airborne Acoustic Effects— Pinnipeds 

that occur near the project site could be 

exposed to airborne sounds associated 

with pile driving, pile removal and DTH 

pile installation 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 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 

exceeding the acoustic thresholds. 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 


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water. 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. 

However, these animals would 

previously have been taken by Level B 

harassment because of exposure to 

underwater sound above the behavioral 

harassment thresholds, which are, in all 

cases, larger than those associated with 

airborne sound. 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 

HRCP’s construction activities could 

have localized, temporary impacts on 

marine mammal habitat by increasing 

in-water sound pressure levels and 

slightly decreasing water quality. 

Construction activities are of short 

duration and would likely have 

temporary impacts on marine mammal 

habitat through increases in underwater 

sound. 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 impact and vibratory pile 

driving, elevated levels of underwater 

noise would ensonify the project area 

where both fish and mammals may 

occur and could affect foraging success. 

Additionally, marine mammals may 

avoid the area during construction, 

however, displacement due to noise is 

expected to be temporary and is not 

expected to result in long-term effects to 

the individuals or populations. 

A localized increase in turbidity near 

the seafloor during construction would 

occur in the immediate area 

surrounding the area where piles are 

installed (and removed in the case of the 

temporary piles). The sediments on the 

sea floor will be disturbed during pile 

driving; however, suspension will be 

brief and localized and is unlikely to 

measurably affect marine mammals or 

their prey in the area. In general, 

turbidity associated with pile 

installation is localized to about a 25-ft 

(7.6-meter) radius around the pile 

(Everitt et al. 1980). Cetaceans are not 

expected to be close enough to the pile 

driving areas to experience effects of 

turbidity, and any pinnipeds could 

avoid localized areas of turbidity. 

Therefore, we expect the impact from 

increased turbidity levels to be 

discountable to marine mammals and 

do not discuss it further. 

In-Water Construction Effects on 

Potential Foraging Habitat 

The proposed activities would not 

result in permanent impacts to habitats 

used directly by marine mammals 

except for the actual footprint of the 

project. The total seafloor area affected 

by pile installation and removal is small 

compared to the vast foraging area 

available to marine mammals in the 

project area and lower Chesapeake Bay. 

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 we anticipate a 

rapid return to normal recruitment, 

distribution and behavior. Any 

behavioral avoidance by fish of the 

disturbed area would still leave large 

areas of fish and marine mammal 

foraging habitat in the nearby vicinity in 

the project area and lower Chesapeake 

Bay. 

In-Water Construction Effects on 

Potential Prey (Fish) 

Sound may affect marine mammals 

through impacts on the abundance, 

behavior, or distribution of prey species 

(e.g., fish). Marine mammal prey varies 

by species, season, and location. Here, 

we describe studies regarding the effects 

of noise on known marine mammal 

prey. 

Fish utilize the soundscape and 

components of sound in their 

environment to perform important 

functions such as foraging, predator 

avoidance, mating, and spawning (e.g., 

Zelick et al., 1999; Fay, 2009). 

Depending on their hearing anatomy 

and peripheral sensory structures, 

which vary among species, fishes hear 

sounds using pressure and particle 

motion sensitivity capabilities and 

detect the motion of surrounding water 

(Fay et al., 2008). The potential effects 

of noise on fishes depends on the 

overlapping frequency range, distance 

from the sound source, water depth of 

exposure, and species-specific hearing 

sensitivity, anatomy, and physiology. 

Key impacts to fishes may include 

behavioral responses, hearing damage, 

barotrauma (pressure-related injuries), 

and mortality. 

Fish react to sounds which are 

especially strong and/or intermittent 

low-frequency sounds, and behavioral 

responses such as flight or avoidance 

are the most likely effects. Short 

duration, sharp sounds can cause overt 

or subtle changes in fish behavior and 

local distribution. The reaction of fish to 

noise depends on the physiological state 

of the fish, past exposures, motivation 

(e.g., feeding, spawning, migration), and 

other environmental factors. Hastings 

and Popper (2005) identified several 

studies that suggest fish may relocate to 

avoid certain areas of sound energy. 

Additional studies have documented 

effects of pile driving on fish (e.g., 

Scholik and Yan, 2001, 2002; Popper 

and Hastings, 2009). Several studies 

have demonstrated that impulse sounds 

might affect the distribution and 

behavior of some fishes, potentially 

impacting foraging opportunities or 

increasing energetic costs (e.g., Fewtrell 

and McCauley, 2012; Pearson et al., 

1992; Skalski et al., 1992; Santulli et al., 

1999; Paxton et al., 2017). However, 

some studies have shown no or slight 

reaction to impulse sounds (e.g., Wardle 

et al., 2001; Jorgenson and Gyselman, 

2009; Cott et al., 2012). 

SPLs of sufficient strength have been 

known to cause injury to fish and fish 

mortality. However, in most fish 

species, hair cells in the ear 

continuously regenerate and loss of 

auditory function likely is restored 

when damaged cells are replaced with 

new cells. Halvorsen et al. (2012a) 

showed that a TTS of 4–6 dB was 

recoverable within 24 hours for one 

species. Impacts would be most severe 

when the individual fish is close to the 

source and when the duration of 

exposure is long. Injury caused by 

barotrauma can range from slight to 

severe and can cause death, and is most 

likely for fish with swim bladders. 

Barotrauma injuries have been 

documented during controlled exposure 

to impact pile driving (Halvorsen et al., 

2012b; Casper et al., 2013). 

The most likely impact to fish from 

pile driving activities at the project 

areas would be temporary behavioral 

avoidance of the area. The duration of 

fish avoidance of an area after pile 

driving stops is unknown, but a rapid 

return to normal recruitment, 

distribution and behavior is anticipated. 

In summary, given the relatively small 

areas being affected, and the fact that 

these areas do not include habitat of 

particularly high quality or importance, 

pile driving and removal 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 


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Federal Register / Vol. 86, No. 5 / Friday, January 8, 2021 / Proposed Rules 1609 

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 LOA, 

which will inform both NMFS’ 

consideration of small numbers and the 

negligible impact determination. 

Harassment is the only type of take 

expected to result from these activities. 

Except with respect to certain activities 

not pertinent here, section 3(18) of the 

MMPA defines harassment as: Any act 

of pursuit, torment, or annoyance which 

(i) has the potential to injure a marine 

mammal or marine mammal stock in the 

wild (Level A harassment); or (ii) has 

the potential to disturb a marine 

mammal or marine mammal stock in the 

wild by causing disruption of behavioral 

patterns, including, but not limited to, 

migration, breathing, nursing, breeding, 

feeding, or sheltering (Level B 

harassment). 

Authorized takes would primarily be 

by Level B harassment, as noise 

generated from in-water pile driving 

(vibratory and impact) has the potential 

to result in disruption of behavioral 

patterns for individual marine 

mammals. There is also some potential 

for auditory injury (Level A harassment) 

to result, primarily for low- and highfrequency species and phocids because 

predicted auditory injury zones are 

larger than for mid-frequency species. 

Auditory injury is unlikely to occur for 

mid-frequency species. The proposed 

mitigation and monitoring measures are 

expected to minimize the severity of 

such taking to the extent practicable. 

As described previously, no serious 

injury or mortality is anticipated or 

proposed to be authorized for this 

activity. Below we describe how the 

take is estimated. 

Generally speaking, we estimate take 

by considering: (1) Acoustic thresholds 

above which marine mammals will be 

behaviorally disturbed 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 proposed take estimate. 

Acoustic Thresholds 

NMFS recommends the use of 

acoustic thresholds that identify the 

received level of underwater sound 

above which exposed marine mammals 

would be reasonably expected to 

experience behavioral disturbance 

(equated to Level B harassment) or to 

incur PTS of some degree (equated to 

Level A harassment). 

Level B Harassment for non-explosive 

sources—Though significantly driven by 

received level, the onset of behavioral 

disturbance from anthropogenic noise 

exposure is also informed to varying 

degrees by other factors related to the 

source (e.g., frequency, predictability, 

duty cycle), the environment (e.g., 

bathymetry), and the receiving animals 

(hearing, motivation, experience, 

demography, behavioral context) and 

can be difficult to predict (Southall et 

al., 2007, Ellison et al., 2012). Based on 

what the available science indicates and 

the practical need to use a threshold 

based on a factor that is both predictable 

and measurable for most activities, 

NMFS uses a generalized acoustic 

threshold based on received level to 

estimate the onset of Level B 

harassment. NMFS predicts that marine 

mammals are likely to experience 

behavioral disturbance in a manner we 

consider Level B harassment when 

exposed to underwater anthropogenic 

noise above received levels of 120 dB re 

1 mPa (rms) for continuous (e.g., 

vibratory pile-driving, drilling) and 

above 160 dB re 1 mPa (rms) for nonexplosive impulsive (e.g., seismic 

airguns) or intermittent (e.g., scientific 

sonar) sources. 

HRCP’s proposed activity includes the 

use of continuous (vibratory pile 

driving, DTH pile installation) and 

impulsive (impact pile driving, DTH 

pile installation), sources, and therefore 

the 120 and 160 dB re 1 mPa (rms) 

criteria are applicable. Note that the 120 

dB criterion is used for DTH pile 

installation, as the continuous noise 

produced through the activity will 

produce the largest harassment 

isopleths. 

Level A harassment for non-explosive 

sources—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 from two different 

types of sources (impulsive or nonimpulsive). As noted previously, 

HRCP’s proposed activity includes the 

use of impulsive (impact pile driving, 

DTH pile installation) and nonimpulsive (vibratory pile driving/ 

removal, DTH pile installation) sources. 

These thresholds are provided in the 

Table 10 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. 

TABLE 10—THRESHOLDS IDENTIFYING THE ONSET OF PERMANENT THRESHOLD SHIFT

Hearing group 

PTS onset acoustic thresholds * 

(received level) 

Impulsive Non-impulsive 

Low-Frequency (LF) Cetaceans/ ..................................... Cell 1: Lpk,flat: 219 dB; LE,LF,24h: 183 dB ......................... Cell 2: LE,LF,24h: 199 dB. 

Mid-Frequency (MF) Cetaceans ...................................... Cell 3: Lpk,flat: 230 dB; LE,MF,24h: 185 dB ........................ Cell 4: LE,MF,24h: 198 dB. 

High-Frequency (HF) Cetaceans ..................................... Cell 5: Lpk,flat: 202 dB; LE,HF,24h: 155 dB ........................ Cell 6: LE,HF,24h: 173 dB. 

Phocid Pinnipeds (PW) (Underwater) ............................. Cell 7: Lpk,flat: 218 dB; LE,PW,24h: 185 dB ....................... Cell 8: LE,PW,24h: 201 dB. 

Otariid Pinnipeds (OW) (Underwater) ............................. Cell 9: Lpk,flat: 232 dB; LE,OW,24h: 203 dB ....................... Cell 10: LE,OW,24h: 219 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. 


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Note: Peak sound pressure (Lpk) has a reference value of 1 μPa, and cumulative sound exposure level (LE) has a reference value of 1μPa2s. 

In this Table, thresholds are abbreviated to reflect American National Standards Institute standards (ANSI 2013). However, peak sound pressure 

is defined by ANSI as incorporating frequency weighting, which is not the intent for this Technical Guidance. Hence, the subscript ‘‘flat’’ is being 

included to indicate peak sound pressure should be flat weighted or unweighted within the generalized hearing range. The subscript associated 

with cumulative sound exposure level thresholds indicates the designated marine mammal auditory weighting function (LF, MF, and HF 

cetaceans, and PW and OW pinnipeds) and that the recommended accumulation period is 24 hours. The cumulative sound exposure level 

thresholds could be exceeded in a multitude of ways (i.e., varying exposure levels and durations, duty cycle). When possible, it is valuable for 

action proponents to indicate the conditions under which these acoustic thresholds will be exceeded. 

Ensonified Area 

Here, we describe operational and 

environmental parameters of the activity 

that will feed into identifying the area 

ensonified above the acoustic 

thresholds, which include source levels 

and transmission loss coefficient. 

The sound field in the project area is 

the existing background noise plus 

additional construction noise from the 

project. Marine mammals are expected 

to be affected via sound generated by 

the primary components of the project 

(i.e., vibratory pile driving, vibratory 

pile removal, impact pile driving, 

jetting, and DTH pile installation). 

Sound source levels (SSLs) for each 

method of installation and removal were 

estimated using empirical 

measurements from similar projects in 

Norfolk and Little Creek (Craney Island), 

elsewhere in Virginia, or outside of 

Virginia (California, Florida, 

Washington, Alaska) (Table 11). It is 

assumed that jetting will be quieter than 

vibratory installation of the same pile 

size, but data for this activity are 

limited; therefore, SSLs for vibratory 

installation have been applied to jetting. 

DTH pile installation includes drilling 

(non-impulsive sound) and hammering 

(impulsive sound) to penetrate rocky 

substrates (Denes et al. 2016; Denes et 

al. 2019; Reyff and Heyvaert 2019). DTH 

pile installation was initially thought be 

a primarily non-impulsive noise source. 

However, Denes et al. (2019) concluded 

from a study conducted in Virginia, 

nearby the location for this project, that 

DTH should be characterized as 

impulsive based on Southall et al. 

(2007), who stated that signals with a >3 

dB difference in sound pressure level in 

a 0.035-second window compared to a 

1-second window can be considered 

impulsive. Therefore, DTH pile 

installation is treated as both an 

impulsive and non-impulsive noise 

source. In order to evaluate Level A 

harassment, DTH pile installation 

activities are evaluated according to the 

impulsive criteria. Level B harassment 

isopleths are determined by applying 

non-impulsive criteria and using the 

120 dB threshold which is also used for 

vibratory driving. This approach 

ensures that the largest ranges to effect 

for both Level A and Level B harassment 

are accounted for in the take estimation 

process. 

The source level employed to derive 

Level B harassment isopleths for DTH 

pile installation of all pile sizes was 

derived from the Denes et al. (2016) 

study at Kodiak, Alaska. The median 

source value for drilling was reported to 

be 166 dB RMS. 

The source level employed to derive 

Level A harassment isopleths for DTH 

pile installation of piles/holes above 24- 

inch up to 42-inch in diameter came 

from a combination of (whichever 

higher for given metric) Reyff and 

Heyvaert (2019), Denes et al. (2019), and 

Reyff (2020). For pile/holes 60-inch in 

diameter, values were provided by Reyff 

(Reyff personal communication) and are 

shown in Table 11. Note that during 

some driving scenarios bubble curtains 

will be used to reduce sound source 

levels by 7 dB from the values recorded 

by Denes et al. (2019) at the nearby 

Chesapeake Bay Bridge Tunnel. These 

are also noted in Table 11. 

TABLE 11—SUMMARY OF PROJECT SOUND SOURCE LEVELS

[a 10 m] 

Method and pile type Sound source level at 10 meters Literature source 

Vibratory Hammer dB rms 

42-inch steel pile ............................................. 168 Austin et al. 2016. 

36-inch steel pile ............................................. 167 DoN 2015. 

30-inch steel pile, concrete filled .................... 167 DoN 2015. 

24-inch steel pile ............................................. 161 DoN 2015. 

16-inch CCA timber pile * ................................ 162 Caltrans 2015. 

AZ 700–19 steel sheet pile ............................. 160 Caltrans 2015. 

AZ 700–26 steel sheet pile ............................. 160 Caltrans 2015. 

Jetting dB rms 

42-inch steel pile ............................................. 161 Austin et al. 2016. 

DTH Pile Installation dB rms dB SEL dB peak 

30-inch and 36-inch steel pipe piles ............... 166 164 196 Denes et al. 2016, 2019; Reyff and Heyvaert 

2019; Reyff 2020. 

60-inch steel pipe pile ..................................... 166 175 196 Denes et al. 2016; Reyff pers. comm. 


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TABLE 11—SUMMARY OF PROJECT SOUND SOURCE LEVELS—Continued 

[a 10 m] 

Method and pile type 

Impact Hammer dB rms dB SEL dB peak 

36-inch steel pile ............................................. 193 183 210 Caltrans 2015; Chesapeake Tunnel Joint 

Venture 2018. 

36-inch steel pile, attenuated ** ...................... 186 176 203 Caltrans 2015; Chesapeake Tunnel Joint 

Venture 2018 ∂. 

30-inch steel pile, concrete filled .................... 195 186 216 DoN 2015. 

30-inch steel pile, concrete filled, attenuated **.188 179 209 DoN 2015. 

24-inch steel pile ............................................. 190 177 203 Caltrans 2015. 

24-inch steel pile, attenuated ** ...................... 183 170 196 Caltrans 2015. 

54-inch concrete cylinder pile *** .................... 187 177 193 MacGillivray et al. 2007. 

24-inch concrete square pile .......................... 176 166 188 Caltrans 2015. 

Note: It is assumed that noise levels during pile installation and removal are similar. dB = decibel: SEL = sound exposure level; dB peak = 

peak sound level; rms = root mean square; DoN = Department of the Navy; CCA = Chromated Copper Arsenate, Caltrans = California Department of Transportation. 

*SSL taken from 12-inch timber piles in Norfolk, Virginia. 

**SSLs are a 7 dB reduction from Chesapeake Tunnel Joint Venture 2018 values due to usage of a bubble curtain. 

***SSLs taken from 36-inch concrete square piles, no project specific information provided. +The primary literature source for 36-inch steel pipe attenuated piles is Caltrans 2015; however, the Chesapeake Tunnel Joint Venture 2018 is 

also cited due to the proximity of the project to the HRBT Project. 

Simultaneous use of hammers could 

result in increased SPLs and harassment 

zone sizes given the proximity of the 

component driving sites and the rules of 

decibel addition. Impact pile 

installation is projected to take place 

concurrently at 3 to 4 locations and 

there is the potential for as many as 7 

pile installation locations operating 

concurrently. NMFS (2018b) handles 

overlapping sound fields created by the 

use of more than one hammer 

differently for impulsive (impact 

hammer and Level A harassment zones 

for drilling with a DTH hammer) and 

continuous sound sources (vibratory 

hammer and Level B harassment zones 

for drilling with a DTH hammer) (See 

Table 12). It is unlikely that the two 

impact hammers would strike at the 

same instant, and therefore, the SPLs 

will not be adjusted regardless of the 

distance between impact hammers. In 

this case, each impact hammer will be 

considered to have its own independent 

Level A and Level B harassment zones 

and drilling with a DTH hammer will be 

considered to have its own independent 

Level A harassment zones. It will be 

unlikely that more than one DTH 

hammer will be used within a day at 

more than one location; therefore, only 

one DTH hammer was included in the 

multiple hammer calculations for Level 

B harassment zones. 

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. The 

method described below was used by 

Washington State Department of 

Transportation (WSDOT) and has been 

used by NMFS (WSDOT 2020). 

When two or more vibratory hammers 

are used simultaneously, and the 

isopleth of one sound source 

encompasses the sound source of 

another isopleth, the sources are 

considered additive and combined 

using the following rules (Table 12) for 

addition of two simultaneous vibratory 

hammers, the difference between the 

two SSLs is calculated, and if that 

difference is between 0 and 1 dB, 3 dB 

are added to the higher SSL; if 

difference is between 2 or 3 dB, 2 dB are 

added to the highest SSL; if the 

difference is between 4 to 9 dB, 1 dB is 

added to the highest SSL; and with 

differences of 10 or more decibels, there 

is no addition. 

TABLE 12—RULES FOR COMBINING SOUND LEVELS GENERATED DURING PILE INSTALLATION

Hammer types Difference in SSL Level A harassment zones Level B harassment zones 

Vibratory, Impact ......... Any ............................. Use impact zones ........................................... Use vibratory zone. 

Impact, Impact ............. Any ............................. Use zones for each pile size and number of 

strikes.

Use zone for each pile size. 

Vibratory, Vibratory ...... 0 or 1 dB .................... Add 3 dB to the higher source level ............... Add 3 dB to the higher source level. 

2 or 3 dB .................... Add 2 dB to the higher source level ............... Add 2 dB to the higher source level. 

4 to 9 dB .................... Add 1 dB to the higher source level ............... Add 1 dB to the higher source level. 

10 dB or more ............ Add 0 dB to the higher source level ............... Add 0 dB to the higher source level. 

When three or more continuous 

sound sources are used concurrently, 

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 


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the above rules, then the combination of 

the lower two is combined with the 

highest of the three. 

It is common for pile installation to 

start and stop multiple times as each 

pile is adjusted and its progress is 

measured and documented. For short 

durations, it is anticipated that multiple 

hammers could be in use 

simultaneously. Following an approach 

modified from WSDOT in their 

Biological Assessment manual and 

described in Table 13, decibel addition 

calculations were carried out for 

possible combinations of vibratory 

installations of 24-, 30-, 36-, and 42-inch 

steel pipe piles throughout the Project 

area. 

These source levels are used to 

compute the Level A harassment zones 

and to estimate the Level B harassment 

zones. 

Level A Harassment Zones 

When the NMFS’ Technical Guidance 

(2016) was published, in recognition of 

the fact that ensonified area/volume 

could be more technically challenging 

to predict because of the duration 

component in the new thresholds, we 

developed a User Spreadsheet that 

includes tools to help predict a simple 

isopleth that can be used in conjunction 

with marine mammal density or 

occurrence to help predict takes. We 

note that because of some of the 

assumptions included in the methods 

used for these tools, we anticipate that 

isopleths produced are typically going 

to be overestimates of some degree, 

which may result in some degree of 

overestimate of 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 in-water pile driving 

activities during the HRBT project, 

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 

(Table 14 and Table 15) and the 

resulting isopleths are reported below 

(Table 14). Level A harassment 

thresholds for impulsive sound sources 

(impact pile driving, DTH pile 

installation) are defined for both 

SELcum and Peak SPL, with the 

threshold that results in the largest 

modeled isopleth for each marine 

mammal hearing group used to establish 

the effective Level A harassment 

isopleth. 

For purposes of estimated take by 

Level A harassment, NMFS assumed 

that the strike rate for impact pile 

installation was 50 percent of the 

estimated number of strikes displayed 

in Table 14 and 15. Similarly, for 

vibratory driving NMFS assumed that 

the driving time for each pile was 50 

percent of the estimated total. For the 

DTH hammer calculations, Reyff and 

Heyvaert 2019 identified a strike rate of 

10 Hz. This was also reduced by 50 

percent to 5 Hz which to achieve the 

same 50 percent Level A harassment 

reduction as was done for impact and 

vibratory driving. Strikes per Pile values 

were not altered when calculating Level 

A harassment zones for DTH pile 

installation. 

Since the marine mammals proposed 

for authorization are highly mobile, it is 

unlikely that an animal would remain 

within an established Level A 

harassment zone for the entire duration 

or number of strikes associated with 

installation or removal of a specified 

number of piles throughout a given day. 

This was done to provide more realistic 

take estimates by Level A harassment. 

NMFS applied this reduction across all 

pile sizes, types, and installation/ 

removal methods as shown in Tables 14 

and 15. Additionally, note that under 

some driving scenarios a 7 dB 

attenuation was applied to impact 

installation of 24-inch steel, 30-inch 

Steel, and 36-inch steel due to use of 

bubble curtains as shown in Table 14. 

The calculated Level A isopleths for 

different size pile and driving types are 

shown in Tables 16–18. 

BILLING CODE 3510–22–P 


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BILLING CODE 3510–22–C 


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TABLE 15—USER SPREADSHEET INPUT PARAMETERS USED FOR CALCULATING LEVEL A HARASSMENT ISOPLETHS FOR

DRILLING WITH A DTH HAMMER * 

Model parameter 

30-inch steel, 

concrete filled 

36-inch steel 60-inch steel 

DTH DTH DTH 

Spreadsheet Tab ............................................................................................................... E.2 E.2 E.2 

Weighting Factor Adjustment (kilohertz) ........................................................................... 2 2 2 

SELss (LE, p, single strike) at 10 meters ................................................................................ 164 164 175 

Lp, 0-pk at 10 meters .......................................................................................................... 196 196 196 

Number of piles per day .................................................................................................... 6 2 3 

Duration to drive a pile (minutes) ...................................................................................... 120 120 120 

Transmission loss coefficient ............................................................................................. 15 15 15 

Distance from source (meters) .......................................................................................... 10 10 10

Estimated Number of Strikes per 24-hour period ............................................................. 432,000 144,000 216,000 

50% of Strikes per 24-hour period .................................................................................... 216,000 72,000 108,000 

Strike rate (Hz) average strikes per second ..................................................................... 10 10 10 

50% of Strike rate (Hz) average strikes per second ......................................................... 5 5 5 

* To provide a more realistic estimate of take by Level A harassment, NMFS assumes that an animal would occur within the vicinity of the construction activity for 50 percent of the pile installation and removal time, which equates to 50 percent of the piles planned for installation and removal. HRCP has implemented this reduction across all pile sizes, types, and installation and removal methods. For drilling with a DTH hammer 

installation, the strike rate (Hz) was reduced by half to accomplish the reduction. A 10 Hz strike rate was identified from Reyff and Heyvaert 2019 

which was then reduced by 50% to 5 Hz to accomplish the 50% Level A reduction. 

TABLE 16—CALCULATED DISTANCES TO LEVEL A HARASSMENT ISOPLETHS DURING VIBRATORY INSTALLATION, AND

VIBRATORY REMOVAL AND JETTING INSTALLATION WITH NO ATTENUATION

Project component Pile size/type 

Minutes per pile 

(reduced by 

half) 

Number of 

piles per 

day 

Level A harassment isopleth distance 

(meters) 

Level A Harassment isopleth areas 

(km2) 

Cetaceans Pinnipeds Cetaceans Pinnipeds 

LF MF HF PW LF MF HF PW 

Vibratory Hammer 

North Trestle 

Moorings .......................................... 42-inch Pipe, Steel .......................... 15 6 27 3 39 16 <0.01 

Template Piles ................................. 36-inch Pipe, Steel .......................... 2.5 8 9 1 13 5 <0.01 

North Shore Work Trestle, Jump 

Trestle, Work Trestle, Demolition 

Trestle.

36-inch Pipe, Steel .......................... 25 2 16 2 23 10 <0.01 

Moorings .......................................... 24-inch Pipe, Steel .......................... 15 6 9 1 14 6 <0.01 

North Shore Abutment ..................... AZ 700–19 Sheet, Steel ................. 15 10 11 1 16 7 <0.01 

North Island 

Moorings .......................................... 42-inch Pipe, Steel .......................... 15 6 27 3 39 16 <0.01 

Hampton Creek Approach Channel 

Marker.

Existing, 36-inch Pipe, Steel ........... 25 1 10 1 15 6 <0.01 

North Island Expansion ................... AZ 700–26 Sheet, Steel ................. 15 10 11 1 16 7 <0.01 

North Island Abutment ..................... AZ 700–19 Sheet, Steel .................

South Island Abutment .................... AZ 700–19 Sheet, Steel ................. 15 10 11 1 16 7 <0.01 

South Island Expansion ................... AZ 700–26 Sheet, Steel .................

Settlement Reduction Piles ............. 24-inch Pipe, Steel .......................... 30 6 15 2 21 9 

Deep Foundation Piles .................... 30-inch Pipe, Steel, Concrete Filled 30 6 36 4 53 22 

TBM Platform ................................... 36-inch Pipe, Steel .......................... 30 2 18 2 26 11 

Conveyor Trestle ............................. 36-inch Pipe, Steel .......................... 25 3 20 2 30 13 

Moorings .......................................... 42-inch Pipe, Steel .......................... 15 6 27 3 39 16 <0.01 

Template Piles ................................. 36-inch Pipe, Steel .......................... 2.5 16 14 2 20 8 <0.01 

South Trestle 

Template Piles ................................. 36-inch Pipe, Steel .......................... 2.5 8 9 1 13 5 <0.01 

Moorings, Casings ........................... 42-inch Pipe, Steel .......................... 15 6 27 3 39 16 <0.01 

Work Trestle, Jump Trestle, Demolition Trestle, Temporary MOT 

Trestle.

36-inch Pipe, Steel .......................... 25 2 16 2 23 10 

Moorings .......................................... 24-inch Pipe, Steel .......................... 15 6 9 1 14 6 

Willoughby Bay 

Moorings .......................................... 24-inch Pipe, Steel .......................... 15 6 9 1 14 6 <0.01 

Work Trestle, Jump Trestle ............. 36-inch Pipe, Steel .......................... 25 2 16 2 23 10 

Moorings (Safe Haven) ................... 42-inch Pipe, Steel .......................... 15 6 27 3 39 16 <0.01 

Casing .............................................. 42-inch Pipe, Steel .......................... 15 6 27 3 39 16 <0.01 

Template Piles ................................. 36-inch Pipe, Steel .......................... 2.5 8 9 1 13 5 <0.01 

Willoughby Spit Laydown Area 

Finger Piers on Timber Piles ........... 16-inch CCA, Timber ...................... 15 4 8 1 12 5 <0.01 

Dock on Spuds, Dock on Piles ....... 36-inch Pipe, Steel .......................... 25 3 20 2 30 13 <0.01 

Template Piles ................................. 36-inch Pipe, Steel .......................... 2.5 16 14 2 20 8 <0.01 

Jetting 

Willoughby Bay 

Casing .............................................. 42-inch Pipe, Steel .......................... 15 1 3 1 4 2 <0.01 


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TABLE 17—CALCULATED DISTANCES TO LEVEL A HARASSMENT ISOPLETHS DURING IMPACT INSTALLATION AND DTH PILE

INSTALLATION WITH NO ATTENUATION

Project component Pile size/type 

Number of 

strikes per 

pile or strike rate* 

(reduced 

by half) 

Number 

of piles 

per day 

Level A harassment isopleth distance 

(meters) 

Level A harassment isopleth areas 

(km2) 

Cetaceans Pinnipeds Cetaceans Pinnipeds 

LF MF HF PW LF MF HF PW 

North Trestle 

Permanent Piles .............................. 54-inch Pipe, Concrete Cylinder ..... 1,050 1 411 15 490 220 0.53 <0.001 0.75 0.15 

Work Trestle, Jump Trestle, Demolition Trestle.36-inch Pipe, Steel .......................... 20 2 117 5 140 63 0.04 <0.001 0.06 0.01 

South Island 

Settlement Reduction Piles ............. 24-inch Pipe, Steel .......................... 20 6 97 4 116 52 0.02 <0.001 0.03 0.01 

Deep Foundation Piles .................... 30-inch Pipe, Steel, Concrete Filled 20 6 386 14 459 207 0.35 <0.001 0.49 0.10 

South Trestle 

Work Trestle, Jump Trestle, Demolition Trestle, Temporary MOT 

Trestle.

36-inch Pipe, Steel .......................... 20 2 117 5 140 63 0.04 <0.001 0.06 0.01 

Permanent Piles .............................. 54-inch Pipe, Concrete Cylinder ..... 1,050 1 411 15 490 220 0.53 <0.001 0.75 0.15 

Willoughby Bay 

Work Trestle, Jump Trestle ............. 36-inch Pipe, Steel .......................... 20 2 117 5 140 63 0.04 <0.001 0.06 0.01 

Permanent Piles .............................. 24-inch Pipe, Concrete Square ...... 1,050 1 76 3 91 41 0.02 <0.001 0.03 <0.01 

Willoughby Spit Laydown Area 

Dock on Spuds, Dock on Piles ....... 36-inch Pipe, Steel .......................... 20 3 154 6 183 82 0.12 0.09 <0.001 0.03 

DTH Pile Installation * 

North Trestle 

Work Trestle, Jump Trestle, Demolition Trestle.36-inch Pipe, Steel .......................... 36,000 2 936 34 1,115 501 1.81 <0.01 2.27 0.78 

Casing .............................................. 60-inch Pipe, Steel .......................... 36,000 3 6,633 236 7,901 3,550 34.04 0.18 43.75 13.03 

South Island 

Deep Foundation Piles .................... 30-inch Pipe, Steel, Concrete Filled 36,000 6 1,946 70 2,318 1,042 8.28 <0.01 11.30 2.49 

South Trestle 

Work Trestle, Jump Trestle, Temporary MOT Trestle, Demolition 

Trestle.

36-inch Pipe, Steel .......................... 36,000 2 936 34 1,115 501 2.67 <0.01 3.67 0.79 

Casing .............................................. 60-inch Pipe, Steel .......................... 36,000 3 6,633 236 7,901 3,550 77.50 0.18 102.16 27.12 

* For DTH Hammer calculations, a 10 Hz strike rate was identified from Reyff and Heyvaert 2019 which was then reduced by 50% to 5 Hz to accomplish the 50% Level A harassment reduction. Strikes per Pile values were not reduced for DTH methods. 

TABLE 18—CALCULATED DISTANCES TO LEVEL A HARASSMENT ISOPLETHS DURING IMPACT INSTALLATION WITH

ATTENUATION

Project component Pile size/type 

Number of 

strikes per pile 

(reduced by 

half) 

Number of 

piles per 

day 

Level A harassment isopleth distance 

(meters) 

Level A harassment isopleth areas 

(km2) 

Cetaceans Pinnipeds Cetaceans Pinnipeds 

LF MF HF PW LF MF HF PW 

Impact Hammer 

South Island 

Settlement Reduction Piles ............. 24-inch Pipe, Steel .......................... 20 6 33 2 40 18 <0.01 

Deep Foundation Piles .................... 30-inch Pipe, Steel, Concrete Filled 20 6 132 5 157 71 0.04 <0.001 0.06 0.01 

South Trestle 

Temporary MOT Trestle ..................

Jump Trestle. 

Work Trestle. 

36-inch Pipe, Steel .......................... 20 2 40 2 48 22 <0.001 0.007 0.002 

Level B Harassment Zones 

Transmission loss (TL) is the decrease 

in acoustic intensity as an acoustic 

pressure wave propagates out from a 

source. TL parameters vary with 

frequency, temperature, sea conditions, 

current, source and receiver depth, 

water depth, water chemistry, and 

bottom composition and topography. 

The general formula for underwater TL 

is: 

TL = B * Log10 (R1/R2), 

Where 

TL = transmission loss in dB 

B = transmission loss coefficient; for practical 

spreading equals 15 

R1 = the distance of the modeled SPL from 

the driven pile, and 

R2 = the distance from the driven pile of the 

initial measurement 

The recommended TL coefficient for 

most nearshore environments is the 

practical spreading value of 15. This 

value results in an expected propagation 

environment that would lie between 

spherical and cylindrical spreading loss 

conditions, which is the most 


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appropriate assumption for HRCP’s 

proposed activity. 

Using the practical spreading model, 

HRCP determined underwater noise 

would fall below the behavioral effects 

threshold of 120 dB rms for marine 

mammals at a maximum radial distance 

of 15,849 m for vibratory pile driving of 

42- and 36-inch diameter piles. Other 

activities including impact driving and 

vibratory installation sheet piles have 

smaller Level B harassment zones. All 

Level B harassment isopleths are 

reported in Table 19 below. It should be 

noted that based on the geography of the 

project area, and pile driving locations, 

in many cases sound will not reach the 

full distance of the Level B harassment 

isopleth. The radial distances provided 

in Table 19 and Table 20 are shown as 

calculated. However, the land areas 

presented in these tables take into 

account truncation by various land 

masses in the project area and only 

shows the in-water ensonified area. 

TABLE 19—DISTANCES TO LEVEL B HARASSMENT ISOPLETHS FOR DIFFERENT PILE SIZES AND TYPES AND METHODS OF

INSTALLATION AND REMOVAL WITH NO ATTENUATION

Location and component Method and pile type 

Level B 

isopleth (m), 

unattenuated 

Level B area 

unattenuated 

(km2) 

Vibratory Hammer (Level B Isopleth = 120 dB) 

North Trestle 

Moorings ...................................................................... 42-inch steel piles ...................................................... 15,849 96.78 

Template Piles ............................................................ 36-inch steel piles ...................................................... 13,594 85.53 

Demolition Trestle ....................................................... 36-inch steel piles ...................................................... 13,594 85.53 

North Shore Work Trestle ........................................... 36-inch steel piles ...................................................... 13,594 85.53 

Jump Trestle ............................................................... 36-inch steel piles ...................................................... 13,594 85.53 

Work Trestle ................................................................ 36-inch steel piles ...................................................... 13,594 85.53 

Moorings ...................................................................... 24-inch steel piles ...................................................... 5,412 25.34 

North Shore Abutment ................................................ AZ 700–19 steel sheet piles ...................................... 4,642 19.81 

North Island 

Moorings North ............................................................ 42-inch steel piles ...................................................... 15,849 103.86 

Moorings South ........................................................... 42-inch steel piles ...................................................... 15,849 201.04 

Hampton Creek Approach Channel Marker ................ 36-inch steel pile ........................................................ 13,594 93.99 

North Island Expansion North ..................................... AZ 700–26 steel sheet piles ...................................... 4,642 26.06 

North Island Expansion South .................................... AZ 700–26 steel sheet piles ...................................... 4,642 36.73 

North Island Abutment North ...................................... AZ 700–19 steel sheet piles ...................................... 4,642 26.06 

North Island Abutment South ...................................... AZ 700–19 steel sheet piles ...................................... 4,642 36.73 

South Island 

Moorings ...................................................................... 42-inch steel piles ...................................................... 15,849 246.86 

Template Piles ............................................................ 36-inch steel piles ...................................................... 13,594 81.75 

TBM Platform .............................................................. 36-inch steel piles ...................................................... 13,594 81.75 

Conveyor Trestle ......................................................... 36-inch steel piles ...................................................... 13,594 81.75 

Deep Foundation Piles ................................................ 30-inch steel piles, concrete filled ............................. 13,594 194.04 

Settlement Reduction Piles ......................................... 24-inch steel piles ...................................................... 5,412 45.10 

South Island Expansion .............................................. AZ 700–26 steel sheet piles ...................................... 4,642 34.69 

South Island Abutment ................................................ AZ 700–19 steel sheet piles ...................................... 4,642 34.69 

South Trestle 

Moorings, Casings ...................................................... 42-inch steel piles ...................................................... 15,849 305.30 

Template Piles ............................................................ 36-inch steel piles ...................................................... 13,594 235.60 

Temporary MOT Trestle .............................................. 36-inch steel piles ...................................................... 13,594 235.60 

Jump Trestle ............................................................... 36-inch steel piles ...................................................... 13,594 235.60 

Work Trestle ................................................................ 36-inch steel piles ...................................................... 13,594 235.60 

Demolition Trestle ....................................................... 36-inch steel piles ...................................................... 13,594 235.60 

Moorings ...................................................................... 24-inch steel piles ...................................................... 5,412 55.87 

Willoughby Bay 

Moorings (Safe Haven) ............................................... 42-inch steel piles ...................................................... 15,849 5.52 

Moorings ...................................................................... 42-inch steel piles ...................................................... 15,849 5.52 

Casing ......................................................................... 42-inch steel piles ...................................................... 15,849 5.52 

Template Piles ............................................................ 36-inch steel piles ...................................................... 13,594 5.52 

Work Trestle ................................................................ 36-inch steel piles ...................................................... 13,594 5.52 

Jump Trestle ............................................................... 36-inch steel piles ...................................................... 13,594 5.52 

Moorings ...................................................................... 24-inch steel piles ...................................................... 5,412 5.52 

Willoughby Spit Laydown Area 

Template Piles ............................................................ 36-inch steel piles ...................................................... 13,594 74.45 

Dock on Spuds ............................................................ 36-inch steel piles ...................................................... 13,594 74.45 

Dock on Piles .............................................................. 36-inch steel piles ...................................................... 13,594 74.45 


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TABLE 19—DISTANCES TO LEVEL B HARASSMENT ISOPLETHS FOR DIFFERENT PILE SIZES AND TYPES AND METHODS OF

INSTALLATION AND REMOVAL WITH NO ATTENUATION—Continued 

Location and component Method and pile type 

Level B 

isopleth (m), 

unattenuated 

Level B area 

unattenuated 

(km2) 

Finger Piers ................................................................. 16-inch CCA timber piles ........................................... 6,310 40.62 

DTH Pile Installation (Level B Isopleth = 120 dB) 

North Trestle Casings ................................................. 60-inch steel piles ...................................................... 11,659 72.28 

North Trestle Work Trestle, Jump Trestle, Demolition 

Piles, Templates.

36-inch steel piles ...................................................... 11,659 72.28 

South Island Deep Foundation Piles .......................... 30-inch steel piles, concrete filled ............................. 11,659 152.79 

South Trestle Casings ................................................. 60-inch steel piles ...................................................... 11,659 184.12 

South Trestle Work Trestle, Jump Trestle, Demolition 

Trestle, Temporary MOT Trestle, Templates.

36-inch steel piles ...................................................... 11,659 14.12 

Willoughby Bay Templates ......................................... 36-inch steel piles ...................................................... 11,659 5.52 

Jetting (Level B Isopleth = 120 dB) 

Willoughby Bay 

Casing ......................................................................... 42-inch steel piles ...................................................... 5,412 5.52 

Impact Hammer (Level B Isopleth = 160 dB) 

North Trestle 

Permanent Piles .......................................................... 54-inch concrete cylinder piles .................................. 631 1.14 

Work Trestle ................................................................ 36-inch steel piles ...................................................... 1,585 3.81 

Jump Trestle ............................................................... 36-inch steel piles ...................................................... 1,585 3.81 

Demolition Trestle ....................................................... 36-inch steel piles ...................................................... 1,585 3.81 

South Island 

Deep Foundation Piles ................................................ 30-inch steel piles, concrete filled ............................. 2,154 9.91 

Settlement Reduction Piles ......................................... 24-inch steel piles ...................................................... 1,000 2.29 

South Trestle 

Permanent Piles .......................................................... 54-inch concrete cylinder piles .................................. 631 1.25 

Work Trestle ................................................................ 36-inch steel piles ...................................................... 1,585 6.84 

Jump Trestle ............................................................... 36-inch steel piles ...................................................... 1,585 6.84 

Temporary MOT Trestle .............................................. 36-inch steel piles ...................................................... 1,585 6.84 

Demolition Trestle ....................................................... 36-inch steel piles ...................................................... 1,585 6.84 

Willoughby Bay 

Permanent Piles .......................................................... 24-inch concrete cylinder piles .................................. 117 0.04 

Work Trestle ................................................................ 36-inch steel piles ...................................................... 1,585 3.15 

Jump Trestle ............................................................... 36-inch steel piles ...................................................... 1,585 3.15 

Willoughby Spit Laydown Area 

Dock on Spuds ............................................................ 36-inch steel piles ...................................................... 1,585 6.03 

Dock on Piles .............................................................. 36-inch steel piles ...................................................... 1,585 6.03 

TABLE 20—DISTANCES TO LEVEL B HARASSMENT ISOPLETHS FOR INSTALLATION AND REMOVAL OF STEEL PIPE PILES

WITH ATTENUATION BUBBLE CURTAIN

Location and component Method and pile type 

Level B 

isopleth (m), 

attenuated 

Level B area 

attenuated 

(km2) 

Impact Hammer (Level B Isopleth = 160 dB) 

South Island 

Deep Foundation Piles ................................................ 30-inch steel piles, concrete filled ............................. 736 1.25 

Settlement Reduction Piles ......................................... 24-inch steel piles ...................................................... 341 0.27 

South Trestle 

Temporary MOT Trestle, Work Trestle, Jump Trestle 36-inch steel piles ...................................................... 541 0.68 


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The daily duration in which more 

than one vibratory hammer or DTH pile 

installation could occur is difficult to 

predict and quantify. As noted 

previously, DTH pile installation is 

considered by NMFS to be both 

impulsive and continuous. Therefore, 

decibel addition will not be used to 

calculate Level A harassment zones 

during concurrent DTH pile installation 

activities. The Level A harassment 

zones for each DTH activity will be 

based on a single DTH hammer. To 

simplify implementation of Level A 

harassment zones for use of more than 

one vibratory hammer within a day and/ 

or during simultaneous use of multiple 

vibratory hammers with overlapping 

isopleths, whether at a single site or 

multiple sites, Level A harassment zone 

sizes were calculated for the longest 

anticipated duration of the largest pile 

sizes that could be installed within a 

day. For example, if 18 42-inch steel 

pipe piles were installed with a 

vibratory hammer on a single day by 

multiple hammers with overlapping 

sound fields, the Level A harassment 

zone for each of the functional hearing 

groups likely to be present near the 

project area would remain smaller than 

100 meters as shown in Table 21 with 

the largest Level A harassment zone 

being 81 m for harbor porpoises. 

However, it is highly unlikely that a 

harbor porpoise could accumulate 

enough sound from the installation of 

multiple piles in multiple locations for 

the duration required to meet the 

calculated Level A harassment 

threshold. Furthermore, installation of 

18 42-inch steel pipe piles likely 

represents an unrealistic level of 

efficiency that will not be achieved in 

the field. Other combinations of pile 

sizes and numbers would result in Level 

A harassment zones smaller than 100 

meters. To be precautionary, shutdown 

zones outlined in Table 21 for each 

species will be implemented for each 

vibratory hammer on days when it is 

anticipated that multiple vibratory 

hammers will be used, whether at a 

single or multiple sites. This mitigation 

measure would also minimize the need 

for onsite coordination among project 

sites and components. 

TABLE 21—DISTANCES TO LEVEL A HARASSMENT ISOPLETHS FOR INSTALLATION OF 42-INCH PILES BY MULTIPLE

VIBRATORY HAMMERS

Pile size/type Minutes per pile 

(reduced by half) 

Number of 

piles per day 

Level A harassment isopleth distance 

(meters) 

Cetaceans Pinnipeds 

LF MF HF PW 

42-inch Pipe, Steel ............................................................................ 15 18 55 5 81 33 

Note: LF = Low-frequency; MF = Mid-frequency; HF = High frequency; PW = Phocids in water. Table does not stipulate the number of active vibratory hammers, 

as Level A effects are cumulative. The piles per day could be split between multiple hammers and not affect the size of Level A zones. 

The size of the Level B harassment 

zone during concurrent operation of 

multiple vibratory hammers will 

depend on the combination of sound 

sources due to decibel addition of 

multiple hammers producing 

continuous noise. The distances to 

Level B harassment isopleths during 

simultaneous installation of piles using 

two or more vibratory hammers is 

shown in Table 22. As noted previously, 

pile installation often involves 

numerous stops and starts of the 

hammer for each pile. Therefore, decibel 

addition is applied only when the 

adjacent continuous sound sources 

experience overlapping sound fields, 

which generally requires close 

proximity of driving locations. 

Furthermore, it is expected to be a rare 

event when three or more 30-, 36-, or 

42-inch piles are being installed 

simultaneously with vibratory hammers. 

TABLE 22—DISTANCES TO LEVEL B 

HARASSMENT ISOPLETHS FOR MULTIPLE HAMMER ADDITIONS

Combined SSL 

(dB) 

Distance to 

level B isopleth 

(meters) 

164 .................................. 8,577 

165 .................................. 10,000 

166 .................................. 11,659 

167 .................................. 13,594 

168 .................................. 15,849 

TABLE 22—DISTANCES TO LEVEL B 

HARASSMENT ISOPLETHS FOR MULTIPLE HAMMER ADDITIONS—Continued 

Combined SSL 

(dB) 

Distance to 

level B isopleth 

(meters) 

169 .................................. 18,478 

170 .................................. 21,544 

171 .................................. 25,119 

172 .................................. 29,286 

173 .................................. 34,145 

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. 

We describe how the information 

provided above is brought together to 

produce a quantitative take estimate. 

Humpback Whale 

While humpback whales are observed 

near the mouth of the Chesapeake Bay 

and the nearshore waters of Virginia 

during winter and spring months, they 

are relatively rare 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. Humpback whale sighting 

data collected by the U.S. Navy near 

Naval Station Norfolk and Virginia 

Beach from 2012 to 2015 (Table 22) 

(Engelhaupt et al. 2014, 2015, 2016) and 

in the mid-Atlantic (including the 

Chesapeake Bay) from 2015 to 2019 

(Table 23) (Aschettino et al. 2015, 2016, 

2017a, 2018, 2019) did not produce high 

enough sample sizes to calculate 

densities, or survey data were not 

collected during systematic line-transect 

surveys. However, 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 

(off the coast of New Jersey) on any 

given day of the year (Whitt et al. 2015). 

In the project area, a similar density 

may be expected, although the project 

area is much smaller. Aschettino et al. 

(2018) observed and tracked two 

individual humpback whales in the 

Hampton Roads (in the James River) 

area of the project area and over the 5- 

year project period (2015–2019), tracked 

12 individual humpback whales west of 

the CBBT (Movebank 2020). Based on 

these data, and the known movement of 

humpback whales from November 

through April at the mouth of the 

Chesapeake Bay, HRCP requested two 

takes every month from May to October 

and three to four each month from 

November through April for the 


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duration of in-water pile installation 

and removal. NMFS concurs with the 

request and therefore, is proposing to 

authorize a total of 172 takes of 

humpback whales over the 5-year 

Project period (Table 24). The largest 

Level A harassment zone of 6,633 

meters for LF cetaceans is associated 

with drilling with a DTH installation of 

60-inch steel pipe piles (casings) (Table 

17). It is unlikely but possible that a 

humpback whale could enter this area. 

Therefore, HRCP requested and NMFS 

is proposing to authorize eight 

humpback whale takes by Level A 

harassment (2 per year excluding Year 

5), 35 Level B harassment takes each 

year for Years 1–4, and 24 Level B 

harassment takes for Year 5 (Table 24). 

TABLE 23—SUMMARY OF INDIVIDUAL HUMPBACK WHALE SIGHTINGS BY MONTH FROM 2012 TO 2019 IN THE CHESAPEAKE

BAY

Month 

Engelhaupt surveys Aschettino surveys 

2012 2013 2014 2015 2015 2016 2017 2018 2019 Total 

January .............. .................... 0 0 7 56 43 106 1 30 243 

February ............ .................... 0 0 0 5 30 84 0 32 151 

March ................ .................... .................... .................... 0 0 10 7 0 1 18 

April ................... .................... 2 1 0 0 .................... .................... .................... 1 4 

May .................... .................... 0 1 0 0 1 .................... .................... 4 6 

June ................... .................... .................... 0 .................... .................... .................... .................... .................... .................... 0 

July .................... .................... 0 0 0 .................... .................... .................... 1 .................... 1 

August ............... .................... 0 .................... 0 .................... .................... .................... .................... .................... 0 

September ......... 0 1 0 .................... .................... .................... .................... .................... .................... 1 

October .............. 0 0 0 .................... .................... .................... 2 .................... .................... 2 

November .......... 0 0 0 .................... .................... 21 8 0 .................... 29 

December .......... .................... .................... 9 .................... 42 30 21 11 .................... 113 

Total ........... 0 3 11 7 103 135 228 13 68 568 

* Source: Engelhaupt et al. 2014, 2015, 2016 (2012–2015 inshore survey data only; not dedicated humpback whale surveys); Aschettino et al. 2015, 2016, 2017a, 

2018, 2019 (2015–2019). Monthly survey data from the 2019–2020 season have not been published; however, Aschettino et al. 2020b reported that during the 2019/ 

2020 field season, which began 21 December 2019 and concluded 27 March 2020, resulted in 44 humpback whale sightings of 60 individuals. 

Bottlenose Dolphin 

The total estimated number of takes 

for bottlenose dolphins in the Project 

area was estimated using a combined 

approach of daily sighting rates and 

density methods from conventional 

line-transect vessel surveys near Naval 

Station Norfolk and adjacent areas near 

Virginia Beach, Virginia, from August 

2012 through August 2015 (Engelhaupt 

et al. 2016). 

HRCP estimated potential exposure 

using daily sighting data for areas west 

of the HRBT area and within the Core 

Monitoring Area (shown in Figure 11– 

1 in the LOA application) and used 

seasonal densities of bottlenose 

dolphins from Engelhaupt et al. (2016) 

for areas northeast of the HRBT Project 

and outside the Core Monitoring Area. 

The Core Monitoring Area will 

encompass the area south of the HRBT 

and north of the Hampton Roads 

Monitor-Merrimac Memorial BridgeTunnel (Interstate 664) with observers 

positioned at key areas to monitor the 

entire geographic area between the 

bridges. This is the area that will be 

ensonified during most of the pile 

installation and removal activities. 

Depending on placement, the observers 

will be able to view west/southwest 

towards Batten Bay and the mouth of 

the Nansemond River. The largest 

ensonified southwest radii extend to the 

south into the James and Nansemond 

rivers, areas where marine mammal 

abundance is anticipated to be low and 

approaching zero. Towards the 

northeast direction, the largest of the 

multiple hammer zones may reach 

beyond the Chesapeake Bay Bridge and 

Tunnel. However, concurrent vibratory 

installation of three or more 30-, 36-, or 

42-inch piles will occur infrequently. 

This approach also factored in the 

number of days of pile installation and 

removal, which is estimated to be 312 

days per year for Years 1–4 and 181 

days for Year 5. Due to the complex 

schedule and the inexact timeline in 


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which parts of the project may be 

completed ahead of or behind schedule, 

trying to quantify the exact number of 

days certain isopleths will be active for 

the purposes of take estimation is 

infeasible. However, these calculations 

reflect the best available data for the 

areas in and around the Project and 

represent a conservative estimate of 

potential exposure based on reasonable 

assumptions. 

Sighting rates (numbers of dolphins 

per day) were determined for each of the 

four seasons from observations located 

in the inshore Chesapeake Bay zone (the 

Chesapeake Bay waters near Naval 

Station Norfolk) which were used to 

estimate potential exposure west of the 

project site and within the Core 

Monitoring Area. Sightings per season 

ranged from 5 in spring to 24 in fall 

while no bottlenose dolphins were 

sighted in the winter months in this 

inshore area (Table 25). Note that the 

winter sighting total of 0 was a result of 

truncating winter survey data to only 

include sighting data within the vicinity 

of the project location. Bottlenose 

dolphin abundance was highest in the 

fall, (24 sightings representing 245 

individuals), followed by the spring (n 

= 156), and summer (n = 115). This data 

was utilized to calculate the number of 

dolphins per day that could be 

anticipated to occur in the project area 

during each season and year. The 

surveyed width for these surveys was 

two nautical miles, which encompasses 

the areas ensonified within the Core 

Monitoring Area during pile installation 

and removal (HDR-Mott MacDonald 

2020). The number of anticipated days 

of in-water pile installation and removal 

for each month was multiplied by the 

average daily sighting rate estimate of 

the number of dolphins per month that 

could be exposed to project noise within 

the Core Monitoring Area. For the 

majority of piles being installed and/or 

removed, the ensonified area is 

constrained by surrounding land 

features and does not extend out into 

Chesapeake Bay. For piles with 

constrained sound fields, this method is 

sufficient to calculate potential 

exposure. 

Table 25 depicts values in the average 

dolphins sighted per day column that 

are from within the Core Monitoring 

Area, which is smaller and closer to the 

river mouth. Values in the seasonal 

density column (individuals per km2) 

are from outside the Core Monitoring 

Area which is farther out in the Bay and 

where there are likely to be more 

dolphins. 

TABLE 25—AVERAGE DAILY SIGHTING RATES AND SEASONAL DENSITIES OF BOTTLENOSE DOLPHINS WITHIN THE

PROJECT AREA

Season 

Number of 

sightings 

per season 

Average number of 

dolphins sighted 

per day within 

core monitoring area 

Seasonal density 

outside core 

monitoring area 

(individuals/km2) 

Spring, March–May .................................................................................................. 5 17.33 1.00

Summer, June–August ............................................................................................ 14 16.43 3.55 

Fall, September–November ..................................................................................... 24 27.22 3.88 

Winter, December–February ................................................................................... 0 0.00 0.63 

Source: Engelhaupt et al. 2016. 

For each month and year, the average 

area within the Level B harassment 

zones and outside the Core Monitoring 

Area was calculated and used to 

estimate potential exposure east of the 

project site and outside the Core 

Monitoring Area. The weighted average 

area within the relevant Level B 

harassment zones outside the Core 

Monitoring Area was used to calculate 

potential exposure or take of bottlenose 

dolphin for each month. The weighting 

incorporated the number of piles that 

produce the different zone sizes 

ensonified by each pile size/hammer/ 

location. The number of piles with each 

different zone size was multiplied by its 

relevant ensonified area; those were 

then summed and the total was divided 

by the total number of piles. 

For example, if there are 5 piles with 

a 20 km2 Level B zone each and 2 piles 

with a 50 km2 Level B zone, the formula 

would be: 

((5 piles * 20 km2/pile) + (2 piles * 50 

km2/pile))/(7 piles) = weighted 

average of 28.6 km2. 

The sum of potential exposures 

within the Core Monitoring Area (daily 

sighting rate method) and outside the 

Core Monitoring Area (density method 

for zones that extend into Chesapeake 

Bay) yields the total number of potential 

bottlenose dolphin exposures (Table 26) 

for each month and year. 

BILLING CODE 3510–22–P 


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BILLING CODE 3510–22–C 

Level A harassment zones and areas 

are relatively small for bottlenose 

dolphins. The largest Level A 

harassment isopleth is 236 m for DTH 

pile installation of 60-inch steel pipe 

piles (casings) at the South Trestle and 

covers an area less than 0.18 km2. Given 

the daily sightings rates shown in Table 

24, and the small Level A harassment 

zones, HRCP and NMFS do not 

anticipate that bottlenose dolphins will 


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actually incur Level A harassment. 

However, because animals may enter 

into a PTS zone before being sighted, 

HRCP has requested authorization of 

Level A harassment for bottlenose 

dolphins as a precaution. Although 

NMFS does not agree that a brief 

sighting of a marine mammal within a 

Level A harassment zone calculated on 

the basis of accumulated energy 

necessarily means that the animal has 

experienced Level A harassment, we 

nevertheless propose to authorize take 

as requested by HRCP. HRCP assumed 

that approximately 1 percent of the total 

harassment exposures will be in the 

form of Level A harassment. HRCP has 

requested and NMFS is proposing to 

authorize 124,045 exposures by Level B 

harassment and 1,257 exposures by 

Level A harassment of bottlenose 

dolphins divided among the 5 project 

construction years (125,302 total 

exposures¥1,257 Level A harassment 

takes = 124,045 Level B harassment 

takes). However, due to the construction 

schedule, these takes will not occur 

equally during each year of the LOA. 

Year 3 of the LOA is expected to have 

306 takes by Level A harassment and 

30,256 takes by Level B harassment for 

a total of 30,562 proposed takes. 

The total number of bottlenose 

dolphin takes by Level A and Level B 

harassment is expected to be split 

between three bottlenose dolphin 

stocks: Western North Atlantic Southern 

Migratory Coastal; Western North 

Atlantic Northern Migratory Coastal; 

and NNCES. There is insufficient data 

available to apportion the requested 

takes precisely to each of these three 

stocks present in the project area. Given 

that most of the NNCES stock are found 

in the Pamlico Sound Estuarine System, 

the Project will assume that no more 

than 200 of the requested takes will be 

from this stock during any given year. 

Since members of the Western North 

Atlantic Northern Migratory Coastal and 

Western North Atlantic Southern 

Migratory Coastal stocks are thought to 

occur in or near the Project area in 

greater numbers, HRCP will 

conservatively assume that no more 

than half of the remaining animals will 

belong to either of these stocks. 

Additionally, a subset of these takes 

would likely be comprised of 

Chesapeake Bay resident dolphins, 

although the size of that population is 

unknown. It is assumed that an animal 

will be taken once over a 24-hour 

period; however, the same individual 

may be taken multiple times over the 

duration of the project. Therefore, both 

the number of takes for each stock and 

the affected population percentages 

represent the maximum potential take 

numbers. 

Harbor Porpoise 

Harbor porpoises are rarely seen in 

the project area although they are 

known to occur in the coastal waters 

near Virginia Beach (Hayes et al. 2020). 

They have been sighted on rare 

occasions in the Chesapeake Bay closer 

to Norfolk. Density data does not exist 

for this species within the project area. 

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 

high enough sample sizes to calculate 

densities. One group of two harbor 

porpoises was seen during spring 2015 

(Engelhaupt et al. 2016). 

HRCP estimated that one group of two 

harbor porpoises could be exposed to 

project-related underwater noise each 

month during the spring (March–May) 

for a total of 6 harbor porpoises takes 

(i.e., 1 group of 2 individuals per month 

× 3 months per year = 6 harbor 

porpoises) per year for Years 1–4, and 

4 harbor porpoise takes in Year 5. 

The largest calculated Level A 

harassment zone for harbor porpoises 

extends 7,901 m from the noise source 

during DTH installation of 60-inch steel 

pipe piles (casings) at the South Trestle, 

for a harassment area of 102.16 km2

(Table 17). However, HRCP has 

proposed a 100-meter shutdown zone 

for harbor porpoises. HRCP has 

requested small numbers of take by 

Level A harassment for harbor porpoises 

during the project. While NMFS does 

not agree that take by Level A 

harassment is likely, due to the duration 

of time a harbor porpoise would be 

required to remain within the Level A 

zone to accumulate enough energy to 

experience PTS, we nevertheless 

propose to authorize limited take as 

requested by HRCP. It is anticipated that 

2 individuals may enter the Level A 

harassment zone during pile installation 

and removal each spring, for a total of 

2 potential Level A harassment 

exposures per year. Therefore, NMFS is 

proposing to authorize 4 takes by Level 

B harassment each spring for Years 1– 

4 (6 total exposures¥2 Level A 

harassment takes = 4 Level B 

harassment takes). In Year 5, NMFS is 

proposing to authorize 2 takes by Level 

B harassment and 2 by Level A 

harassment. 

Harbor Seal 

HRCP estimated the expected number 

of harbor seals in the project area 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 April 

2019 (Rees et al. 2016; Jones et al. 2018; 

Jones and Rees 2020). The number of 

harbor seals sighted by month from 

2014 through 2019, in the Chesapeake 

Bay waters, in the vicinity (lower 

Chesapeake Bay along the CBBT) of the 

Project, ranged from 0 to 170 

individuals Table 27. During the months 

of June through October (Table 27 and 

Table 29) harbor seals are not 

anticipated to be present in the 

Chesapeake Bay. 

TABLE 27—SUMMARY OF HISTORICAL HARBOR SEAL SIGHTINGS BY MONTH FROM 2014 TO 2019 

Month 2014 2015 2016 2017 2018 2019 Monthly 

average 

January .................................................................................... .............. .............. 33 120 170 7 82.5 

February ................................................................................... .............. 39 80 106 159 21 81 

March ....................................................................................... .............. 55 61 41 0 18 43.8 

April .......................................................................................... .............. 10 1 3 3 4 4.2 

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 3 .............. 1.3 


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TABLE 27—SUMMARY OF HISTORICAL HARBOR SEAL SIGHTINGS BY MONTH FROM 2014 TO 2019—Continued 

Month 2014 2015 2016 2017 2018 2019 Monthly 

average 

December ................................................................................. 4 9 24 8 29 .............. 14.8 

TABLE 28—HARBOR SEAL SURVEY EFFORT, TOTAL COUNT, MAX COUNT ON A SINGLE SURVEY DAY, AND THE AVERAGE

NUMBER OF SEALS OBSERVED PER SURVEY DAY AT THE CBBT SURVEY AREA

Field season Number of 

survey days 

Total 

seal count 

Average daily 

seal count 

Max daily 

seal count 

2014–2015 ....................................................................................................... 11 113 10 33 

2015–2016 ....................................................................................................... 14 187 13 39 

2016–2017 ....................................................................................................... 22 308 14 40 

2017–2018 ....................................................................................................... 15 340 23 45 

2018–2019 ....................................................................................................... 10 82 8 17 

Average ............................................................................................................ 14.4 186 13.6 34.8 

TABLE 29—SUMMARY OF THE ESTIMATED NUMBERS OF HARBOR SEALS POTENTIALLY TAKEN BY LEVEL A AND LEVEL B 

HARASSMENT PER MONTH PER YEAR 1

Year Nov Dec Jan Feb Mar Apr May Level A Level B Annual 

total 

Year 1 .................................................................................... 176.8 367.2 353.6 326.4 367.2 353.6 176.8 424 1,697 2,122 

Year 2 .................................................................................... 176.8 367.2 353.6 326.4 367.2 353.6 176.8 424 1,697 2,122 

Year 3 .................................................................................... 176.8 367.2 353.6 326.4 367.2 353.6 176.8 424 1,697 2,122 

Year 4 .................................................................................... 176.8 367.2 353.6 326.4 367.2 353.6 176.8 424 1,697 2,122 

Year 5 * .................................................................................. 176.8 367.2 353.6 326.4 367.2 0 0 318 1,273 1,591 

Monthly 5-Year Total ............................................................. 884 1,836 1,768 1,632 1,836 1,414 707 2,015 8,062 10,077 

1 Harbor seals not expected June–October. 

The estimated total number of harbor 

seals potentially exposed to in-water 

noise at harassment levels is 13.6 per 

day (the average of the 5-year average 

daily harbor seal count) (Table 28) for 

156 days based on a 6-day work week 

from mid-November to mid-May. Seals 

are not expected to be present in the 

Chesapeake Bay from June through 

October. It is estimated that 13.6 harbor 

seals could be exposed per day to 

Project-related underwater noise for 156 

days for a total of 2,122 exposures per 

year for Years 1–4. In Year 5, it is 

estimated that 1,591 harbor seals could 

be exposed to Project-related 

underwater noise from November 

through March (Table 29). 

The largest Level A harassment 

isopleth associated with drilling with a 

DTH hammer of 60-inch steel pipe piles 

(casings) at the South Trestle for harbor 

seals is 3,550 meters (Table 17) with a 

Level A harassment zone of 27.12 km2. 

It is possible that harbor seals could 

enter this or other Level A harassment 

zones undetected. While NMFS does 

not believe that take of harbor seals by 

Level A harassment is likely due to 

accumulated energy that would be 

required to experience injury, we 

nevertheless propose to authorize 

limited take as requested by HRCP. It is 

anticipated that up to 20 percent of the 

total exposures would be at or above the 

Level A harassment threshold. 

Therefore, HRCP has requested and 

NMFS proposes to authorize 1,697 takes 

by Level B harassment and 424 takes by 

Level A harassment for project years 1– 

4 and 1,273 Level B harassment takes 

and 318 Level A harassment takes of 

harbor seals for project year 5 (Table 

29). 

Gray Seal 

Gray seals are expected to be very 

uncommon in the Project area. As 

described below, historical data indicate 

that approximately one gray seal has 

been seen per year in the Chesapeake 

Bay. Similar to the harbor seal, HRCP 

estimated the expected number of gray 

seals in the Project area 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 2019 (Rees et al. 

2016; Jones et al. 2018; Jones and Rees 

2020). Gray seals are not expected to be 

present in the Chesapeake Bay during 

the months of March through December. 

Between 2015 and 2019 only three 

individual seals were observed, all in 

the month of February (i.e., 2015, 2016 

and 2018). 

As a precautionary measure, HRCP 

assumed that there could be three gray 

seals taken by Level B harassment 

during each of the winter months 

(December through February). 

Therefore, HRCP requested and NMFS 

is proposing to authorize nine gray seal 

takes per year for years 1–4 (3 gray seals 

per month × 3 months per year = 9 gray 

seals) and 5 for project year five for a 

total of 41 takes of gray seals (Table 30). 

Given the size of the Level A 

harassment zones and potential for a 

gray seal to be present within the zone 

for sufficient duration to incur injury, 

nine takes by Level A harassment have 

also been requested (2 during years 1– 

4 and 1 during year 5). NMFS concurs 

with this assessment and is proposing to 

authorize seven takes by Level B 

harassment per year for years 1–4 (9 

takes¥2 takes by Level A harassment = 

7 takes by Level B harassment) and 4 

takes for year 5 (5 total takes¥1 take by 

Level A harassment = 4 takes by Level 

B harassment). NMFS is also proposing 

to authorize 2 takes of gray seal per year 

by Level A harassment for years 1–4 and 

a single take for year 5. 

Table 30 below summarizes proposed 

take numbers by species per project year 

while Table 31 describes the proposed 

authorized take for all the species 

described above as a percentage of stock 

abundance. 


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TABLE 30—ESTIMATED TAKE BY LEVEL A AND LEVEL B HARASSMENT, BY SPECIES

Species 

2021 2022 2023 2024 2025 

Total 

Level A Level B Level A Level B Level A Level B Level A Level B Level A Level B 

Humpback whale ................... 2 35 2 35 2 35 2 35 0 24 172 

Bottlenose dolphin ................. 212 20,915 349 34,435 354 34,972 307 30,341 35 3,382 125,302 

Harbor porpoise .................... 2 4 2 4 2 4 2 4 2 2 30 

Harbor seal ............................ 424 1,697 424 1,697 424 1,697 424 1,697 318 1,273 10,075 

Gray seal ............................... 2 7 2 7 2 7 2 7 1 4 41 

TABLE 31—MAXIMUM ANNUAL ESTIMATED TAKE BY LEVEL A AND LEVEL B HARASSMENT, BY SPECIES AND STOCK IN

COMPARISON TO STOCK ABUNDANCE

Species Stock Stock 

abundance 

Level A 

harassment 

take 

Level B 

harassment 

take 

Percent of 

stock 

Humpback Whale .............................. Gulf of Maine .................................... b 12,312 2 35 0.3 

Bottlenose Dolphin ............................ WNA Coastal, Northern Migratory a 6,639 175 17,386 264.5 

WNA Coastal, Southern Migratory a 3,751 175 17,386 468.2 

NNCESc ........................................... 823 0 200 24.3 

Harbor Porpoise ................................ Gulf of Maine/Bay of Fundy ............. 95,543 2 4 <0.01 

Harbor Seal ....................................... Western North Atlantic ..................... 75,834 424 1,697 2.8 

Gray Seal .......................................... Western North Atlantic ..................... 451,531 2 7 <0.01 

aTake estimates are weighted based on calculated percentages of population for each distinct stock, assuming animals present would follow 

same probability of presence in the project area. Please see the Small Numbers section for additional information. bWest Indies DPS. 

cAssumes multiple repeated takes of same individuals from small portion of each stock as well as repeated takes of Chesapeake Bay resident 

population (size unknown). Please see the Small Numbers section for additional information. 

Proposed Mitigation 

In order to issue an LOA under 

Section 101(a)(5)(A) 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 planned) the likelihood 

of effective implementation (probability 

implemented as planned); and 

(2) The practicability of the measures 

for applicant implementation, which 

may consider such things as cost, 

impact on operations, and, in the case 

of a military readiness activity, 

personnel safety, practicality of 

implementation, and impact on the 

effectiveness of the military readiness 

activity. 

In addition to the measures described 

later in this section, HRCP will employ 

the following mitigation measures: 

• For in-water heavy machinery work 

other than pile driving, if a marine 

mammal comes within 10 m, operations 

shall cease and vessels shall reduce 

speed to the minimum level required to 

maintain steerage and safe working 

conditions; 

• HRCP will conduct briefings 

between construction supervisors and 

crews and the marine mammal 

monitoring team prior to the start of all 

pile driving activity and when new 

personnel join the work, to explain 

responsibilities, communication 

procedures, marine mammal monitoring 

protocol, and operational procedures; 

• For those marine mammals for 

which Level A or Level B harassment 

take has not been requested, in-water 

pile installation/removal will shut down 

immediately if such species are 

observed within or entering the Level A 

or Level B harassment zone; and 

• If take reaches the authorized limit 

for an authorized species, pile 

installation/removal will shut down 

immediately if these species approach 

the Level A or Level B harassment zone 

to avoid additional take. 

The following mitigation measures 

apply to HRCP’s in-water construction 

activities. 

Time Restriction 

For pile driving, work would occur 

only during daylight hours, when visual 

monitoring of marine mammals can be 

conducted. Installation or removal of 

new piles will not commence after 

daylight hours. 

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. 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). In some 

instances, however, large zone sizes will 

make it impossible to monitor the 

entirety of the Level A harassment 

zones. 


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During use of a single hammer the 

following measures will be employed by 

HRCP: 

• A minimum 10-meter shutdown 

zone will be implemented for all 

species, pile sizes, and hammer types to 

prevent direct injury of marine 

mammals. 

• A 15-meter shutdown zone will be 

implemented for seals to prevent direct 

injury. 

• A 100-meter shutdown zone will be 

implemented for harbor porpoises when 

utilizing a DTH hammer and impact 

hammering to prevent direct injury. 

• When the Level A harassment zone 

is larger than 50 meters, shutdown 

zones have been rounded up relative to 

the calculated Level A harassment zones 

as a precautionary measure. HRCP will 

also document the duration any animal 

spends within the Level A harassment 

zone. 

When two or more vibratory hammers 

are in use HRCP will employ the 

following measures: 

• A shutdown zone will be 

implemented for each species for each 

vibratory hammer on days when it is 

anticipated that multiple vibratory 

hammers will be used, whether at a 

single site or multiple sites. 

• A 35-meter shutdown zone will be 

implemented for harbor seals and gray 

seals to prevent direct injury. 

• An 85-meter shutdown zone will be 

implemented for harbor porpoise to 

prevent direct injury. 

• A 55-meter shutdown zone will be 

implemented for humpback whales to 

prevent direct injury. 

Calculated Level A harassment zones 

and shutdown zones for each activity 

and pile size and type are depicted in 

Table 32 and Table 33. Note that 

shutdown zones in Table 33 include a 

7 dB reduction due to the use of bubble 

curtains. Compare shutdown zones in 

Table 32 with Level A harassment zones 

contained in Tables 16, 17 and 18. 

Under some pile driving scenarios, the 

Level A harassment zones are larger 

than the specified shutdown zones. 

TABLE 32—SHUTDOWN ZONES WITH NO ATTENUATION FOR ALL SPECIES

Method Pile size and type 

Minutes (min) per 

pile or strikes per 

pile 

Number of 

piles installed 

or removed 

per day 

Level A harassment isopleth distance 

(meters) 

Cetaceans 

Pinnipeds 

LF MF HF 

Vibratory Installation and Removal 24-inch Pipe, Steel ............................. 15 min .................... 6 110/55 10 214/85 

15/55 

315/35 

21/85 

30-inch Pipe, Steel, Concrete Filled 30 min .................... 6 36/55 60/85 

36-inch Pipe, Steel ............................. 2.5 min ................... 8 10/55 13/85 

2.5 min ................... 16 14/55 20/85 

25 min .................... 1 10/55 15/85 

2 16/55 23/85 

3 20/55 30/85 

30 min .................... 2 18/55 26/85 

42-inch Pipe, Steel ............................. 15 min .................... 6 27/55 39/85 

Sheet, Steel ........................................ 15 min .................... 10 11/55 16/85 

16-inch CCA, Timber .......................... 15 min .................... 4 10/55 12/85 

Jetting .............................................. 42-inch Pipe, Steel ............................. 15 min .................... 1 10 10 

Down-the-Hole Installation 30-inch Pipe, Steel, Concrete Filled ... 36,000 strikes* ....... 6 1,950 70 100 

36-inch Pipe, Steel ............................. 2 940 34 

60-inch Pipe, Steel ............................. 3 6,640 240 

Impact Installation 24-inch Pipe, Steel ............................. 20 strikes ................ 6 100 10 

30-inch Pipe, Steel, Concrete Filled ... 390 14 

36-inch Pipe, Steel ............................. 2 120 10 

36-inch Pipe, Steel ............................. 3 160 10 

24-inch Pipe, Concrete Square .......... 1,050 strikes ........... 1 80 10 

54-inch Pipe, Concrete Cylinder ......... 420 15 

1A 55-meter shutdown zone will be implemented for humpback whales during concurrent vibratory driving of two or more hammers. 

2A 85-meter shutdown zone will be implemented for harbor porpoise during concurrent vibratory driving of two or more hammers. 

3A 35-meter shutdown zone will be implemented for harbor seals and gray seals during concurrent vibratory driving of two or more hammers. 

TABLE 33—SHUTDOWN ZONES WITH ATTENUATION FOR ALL SPECIES

Method Pile size and type Strikes 

per pile 

Number 

of piles 

per day 

Level A harassment isopleth distance 

(meters) 

Cetaceans Pinnipeds 

LF MF HF PW 

Impact Installation 24-inch Pipe, Steel ................. 20 strikes ... 6 33 10 40 18 

30-inch Pipe, Steel, Concrete 

Filled.

140 10 160 80 

36-inch Pipe, Steel ................. 20 strikes ... 2 40 10 48 22 

Protected Species Observers 

The placement of protected species 

observers (PSOs) during all pile driving 

and removal activities (described in the 

Proposed Monitoring and Reporting 

section) will ensure that the entire 

shutdown zone is visible during pile 

driving and removal. Should 

environmental conditions deteriorate 

such that marine mammals within the 

entire shutdown zone would not be 

visible (e.g., fog, heavy rain), pile 

driving and removal must be delayed 

until the PSO is confident marine 

mammals within the shutdown zone 

could be detected. However, if work on 

a pile has already begun, work is 

allowed to continue until that pile is 

installed. 


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Establishment of Level A and Level B 

Harassment Zones 

HRCP will establish monitoring zones 

based on calculated Level A harassment 

isopleths associated with specific pile 

driving activities and scenarios. These 

are areas beyond the established 

shutdown zones in which animals could 

be exposed to sound levels that could 

result in Level A harassment in the form 

of PTS. HRCP will also establish and 

monitor Level B harassment zones 

which are areas where SPLs are equal to 

or exceed the 160 dB rms threshold for 

impact driving and 120 dB rms 

threshold during vibratory driving and 

DTH pile installation. 

The Level A and Level B harassment 

monitoring zones are given in Tables 

16–19. 

Monitoring for Level B Harassment 

HRCP will monitor the Level B 

harassment zones to the extent 

practicable, as well as Level A 

harassment zones extending beyond 

shutdown zones. HRCP will monitor at 

least a portion of the Level B harassment 

zone on all pile driving days. 

Monitoring zones provide utility for 

observing by establishing monitoring 

protocols for areas adjacent to the 

shutdown zones. Monitoring zones 

enable observers to be aware of and 

communicate the presence of marine 

mammals in the project area outside the 

shutdown zone and thus prepare for a 

potential cessation of activity should the 

animal enter the shutdown zone. 

Bubble Curtains 

Use of air bubble curtain systems will 

be implemented by HRCP during impact 

driving of steel piles except in situations 

where the water depth is less than 20 ft 

in depth. The use of this sound 

attenuation device will reduce SPLs and 

the size of the zones of influence for 

Level A harassment and Level B 

harassment. Bubble curtains will 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 shall 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 shall be 

operated such that there is proper 

(equal) balancing of air flow to all 

bubblers. 

• The applicant shall require that 

construction contractors train personnel 

in the proper balancing of air flow to the 

bubblers and corrections to the 

attenuation device to meet the 

performance standards. This shall occur 

prior to the initiation of pile driving 

activities. 

Soft-Start 

The use of soft-start procedures are 

believed to provide additional 

protection to marine mammals by 

providing warning and/or giving marine 

mammals a chance to leave the area 

prior to the hammer operating at full 

capacity. For impact pile driving, HRCP 

will be required to provide an initial set 

of strikes from the hammer at reduced 

energy, with each strike followed by a 

30-second waiting period. This 

procedure will be conducted a total of 

three times before impact pile driving 

begins. Soft start will be implemented at 

the start of each day’s impact pile 

driving and at any time following 

cessation of impact pile driving for a 

period of 30 minutes or longer. Soft start 

is not required during vibratory or DTH 

pile driving activities. 

If a marine mammal is present within 

the shutdown zone, ramping up will be 

delayed until the PSO has determined, 

through sighting, that the animal(s) has 

moved outside the shutdown zone. If a 

marine mammal is present in the Level 

A or Level B harassment zone, ramping 

up may begin and a Level A or Level B 

harassment take will be recorded. If a 

marine mammal is present in the Level 

A or Level B harassment zone, HRCP 

may elect to delay ramping up to avoid 

a Level A or Level B harassment take. 

To avoid a take by Level A or Level B 

harassment, ramping up will begin only 

after the PSO has determined, through 

sighting, that the animal(s) has moved 

outside the corresponding Level A or 

Level B harassment zone or 15 minutes 

have passed. 

Pre-Activity Monitoring 

Prior to the start of daily in-water 

construction activity, or whenever a 

break in pile driving of 30 minutes or 

longer occurs, PSOs will observe the 

shutdown and monitoring zones for a 

period of 30 minutes. The shutdown 

zone will be cleared when a marine 

mammal has not been observed within 

the zone for that 30-minute period. If a 

marine mammal is observed within the 

shutdown zone, a soft-start cannot 

proceed until the animal has left the 

zone or has not been observed for 15 

minutes. If the Level A and Level B 

harassment zones have been observed 

for 30 minutes and non-permitted 

species are not present within the zone, 

soft start procedures can commence and 

work can continue even if visibility 

becomes impaired within the Level A or 

Level B harassment monitoring zones. 

When a marine mammal permitted for 

take by Level A or Level B harassment 

is present in the Level A or Level B 

harassment zone, activities may begin 

and Level A or Level B harassment take 

will be recorded as appropriate. If work 

ceases for more than 30 minutes, the 

pre-activity monitoring of both the Level 

B harassment and shutdown zone will 

commence again. Additionally, in-water 

construction activity must be delayed or 

cease, if poor environmental conditions 

restrict full visibility of the shut-down 

zone(s) until the entire shut-down 

zone(s) is visible. 

Based on our evaluation of HRCP’s 

proposed measures, as well as other 

measures considered by NMFS, NMFS 

has preliminarily determined that the 

proposed mitigation measures provide 

the means of effecting the least 

practicable impact on the affected 

species or stocks and their habitat, 

paying particular attention to rookeries, 

mating grounds, and areas of similar 

significance. 

Proposed Monitoring and Reporting 

In order to issue an LOA for an 

activity, section 101(a)(5)(A) of the 

MMPA states that NMFS must set forth 

requirements pertaining to the 

monitoring and reporting of such taking. 

NMFS’ MMPA implementing 

regulations further describe the 

information that an applicant should 

provide when requesting an 

authorization (50 CFR 216.104 (a)(13)), 

including the means of accomplishing 

the necessary monitoring and reporting 

that will result in increased knowledge 

of the species and the level of taking or 

impacts on populations of marine 

mammals. Monitoring and reporting 

requirements prescribed by NMFS 

should contribute to improved 

understanding of one or more of the 

following: 

• Occurrence of marine mammal 

species or stocks in the area in which 

take is anticipated (e.g., presence, 

abundance, distribution, density). 

• Nature, scope, or context of likely 

marine mammal exposure to potential 

stressors/impacts (individual or 

cumulative, acute or chronic), through 

better understanding of: (1) Action or 

environment (e.g., source 

characterization, propagation, ambient 

noise); (2) affected species (e.g., life 

history, dive patterns); (3) co-occurrence 

of marine mammal species with the 

action; or (4) biological or behavioral 

context of exposure (e.g., age, calving or 

feeding areas). 


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• Individual marine mammal 

responses (behavioral or physiological) 

to acoustic stressors (acute, chronic, or 

cumulative), other stressors, or 

cumulative impacts from multiple 

stressors. 

• How anticipated responses to 

stressors impact either: (1) Long-term 

fitness and survival of individual 

marine mammals; or (2) populations, 

species, or stocks. 

• Effects on marine mammal habitat 

(e.g., marine mammal prey species, 

acoustic habitat, or other important 

physical components of marine 

mammal habitat). 

• Mitigation and monitoring 

effectiveness. 

HRCP will submit a Marine Mammal 

Monitoring Plan which must be 

approved by NMFS in advance of the 

start of construction. 

Visual Monitoring 

Marine mammal monitoring during 

pile driving and removal must be 

conducted by PSOs in a manner 

consistent with the following: 

• Independent PSOs (i.e., not 

construction personnel) who have no 

other assigned tasks during monitoring 

periods must be used; 

• At least one PSO must have prior 

experience performing the duties of a 

PSO during construction activity 

pursuant to a NMFS-issued incidental 

take authorization; 

• Other PSOs may substitute 

education (degree in biological science 

or related field) or training for 

experience; 

• Where a team of three or more PSOs 

is required, a lead observer or 

monitoring coordinator must be 

designated. The lead observer must have 

prior experience working as a marine 

mammal observer during construction; 

and 

• HRCP must submit PSO Curriculum 

Vitae for approval by NMFS prior to the 

onset of pile driving. 

PSOs must have the following 

additional qualifications: 

• Ability to conduct field 

observations and collect data according 

to assigned protocols; 

• Experience or training in the field 

identification of marine mammals, 

including the identification of 

behaviors; 

• Sufficient training, orientation, or 

experience with the construction 

operation to provide for personal safety 

during observations; 

• Writing skills sufficient to prepare a 

report of observations including but not 

limited to the number and species of 

marine mammals observed; dates and 

times when in-water construction 

activities were conducted; dates, times, 

and reason for implementation of 

mitigation (or why mitigation was not 

implemented when required); and 

marine mammal behavior; and 

• Ability to communicate orally, by 

radio or in person, with project 

personnel to provide real-time 

information on marine mammals 

observed in the area as necessary. 

PSOs will be positioned at the best 

practical vantage point(s). The 

position(s) may vary based on 

construction activity and location of 

piles or equipment. At least one of the 

monitoring locations will have an 

unobstructed view of the pile being 

driven, and an unobstructed view of the 

Level A shutdown and Level B 

harassment zones, Core Monitoring 

Area, as well as the 100-meter shutdown 

zone. 

Between one and four PSOs will be 

stationed at locations offering the best 

available views of the Level A and Level 

B harassment monitoring zones during 

in-water pile installation and removal, 

depending on where active in-water 

work is taking place. It is anticipated 

that a PSO will observe from the North 

Island when in-water pile installation is 

occurring at the North Island and North 

Trestle. If the view field is adequate, 

Level A and Level B harassment zones 

may be monitored for multiple pile 

driving locations by the same individual 

PSO. Two PSOs will be located at the 

South Island, where they will monitor 

for marine mammals passing into and 

out of the Core Monitoring Area as well 

as monitor the active hammer sites. This 

location also provides good views to the 

east for monitoring when zones extend 

beyond the Core Monitoring Area into 

Chesapeake Bay. One PSO will be 

stationed on Willoughby Spit or a 

similar location that offers the best 

available views of the Level A and Level 

B harassment monitoring zones during 

in-water pile installation and removal 

within Willoughby Bay. Finally, on days 

when use of multiple hammers is 

planned and it is anticipated that the 

Level B harassment isopleth will 

encompass the CBBT, a PSO will be 

located on one of the CBBT Portal 

Islands to monitor the extended 

ensonified area. A central position will 

generally be staffed by the lead PSO, 

who will monitor the shutdown zones 

and communicate with construction 

personnel about shutdowns and take 

management. PSOs at the pile 

installation and removal locations will 

be able to see at least a radius around 

the construction site that exceeds the 

largest Level A harassment zone. PSOs 

will watch for marine mammals 

entering and leaving the James River 

and will alert the lead PSO of the 

number and species sighted, so that no 

unexpected marine mammals will 

approach the construction site. This will 

minimize Level A harassment take of all 

species. 

Decibel addition is not a 

consideration when sound fields do not 

overlap at the sound sources. 

Willoughby Bay is largely surrounded 

by land, and sound will be prevented 

from propagating to other Project 

construction sites. Therefore, 

Willoughby Bay will be treated as an 

independent site with its own 

monitoring and shutdown zones, as well 

as observer requirements when 

construction is taking place within the 

bay. The Bay is relatively small and will 

be monitored from the construction site 

by one to two observers. 

Reporting 

HRCP would submit an annual draft 

report for each construction year to 

NMFS within 90 calendar days of the 

completion of marine mammal 

monitoring. A final annual report will 

be prepared and submitted to NMFS 

within 30 days following receipt of 

comments on the draft report from 

NMFS. 

The report will detail the monitoring 

protocol and summarize the data 

recorded during monitoring. 

Specifically, the report must include 

• Dates and times (begin and end) of 

all marine mammal monitoring. 

• 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). 

• Environmental conditions during 

monitoring periods (at beginning and 

end of PSO shift and whenever 

conditions change significantly), 

including Beaufort sea state and any 

other relevant weather conditions 

including cloud cover, fog, sun glare, 

and overall visibility to the horizon, and 

estimated observable distance (if less 

than the harassment zone distance). 

• 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. 

• Age and sex class, if possible, of all 

marine mammals observed. 

• PSO locations during marine 

mammal monitoring. 

• 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). 

• Description of any marine mammal 

behavior patterns during observation, 

including direction of travel and 


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estimated time spent within the Level A 

and Level B harassment zones while the 

source was active. 

• Number of marine mammals 

detected within the harassment zones, 

by species. 

• 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. 

• 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. 

If no comments are received from 

NMFS within 30 days, the draft report 

will constitute the final report. If 

comments are received, a final report 

addressing NMFS comments must be 

submitted within 30 days after receipt of 

comments. 

In the event that personnel involved 

in the construction activities discover 

an injured or dead marine mammal, 

HRCP shall report the incident to the 

Office of Protected Resources (OPR) 

(301–427–8401), NMFS and to the 

Greater Atlantic Region New England/ 

Mid-Atlantic Regional Stranding 

Coordinator as soon as feasible. If the 

death or injury was clearly caused by 

the specified activity, HRCP must 

immediately cease the specified 

activities until NMFS is able to review 

the circumstances of the incident and 

determine what, if any, additional 

measures are appropriate to ensure 

compliance with the terms of the 

authorization. HRCP must not resume 

their activities until notified by NMFS. 

The report must include the following 

information: 

i. Time, date, and location (latitude/ 

longitude) of the first discovery (and 

updated location information if known 

and applicable); 

ii. Species identification (if known) or 

description of the animal(s) involved; 

iii. Condition of the animal(s) 

(including carcass condition if the 

animal is dead); 

iv. Observed behaviors of the 

animal(s), if alive; 

v. If available, photographs or video 

footage of the animal(s); and 

vi. General circumstances under 

which the animal was discovered. 

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., populationlevel effects). An estimate of the number 

of takes alone is not enough information 

on which to base an impact 

determination. In addition to 

considering estimates of the number of 

marine mammals that might be ‘‘taken’’ 

through harassment, NMFS considers 

other factors, such as the likely nature 

of any responses (e.g., intensity, 

duration), the context of any responses 

(e.g., critical reproductive time or 

location, migration), as well as effects 

on habitat, and the likely effectiveness 

of the mitigation. We also assess the 

number, intensity, and context of 

estimated takes by evaluating this 

information relative to population 

status. Consistent with the 1989 

preamble for NMFS’s implementing 

regulations (54 FR 40338; September 29, 

1989), the impacts from other past and 

ongoing anthropogenic activities are 

incorporated into this analysis via their 

impacts on the environmental baseline 

(e.g., as reflected in the regulatory status 

of the species, population size and 

growth rate where known, ongoing 

sources of human-caused mortality, or 

ambient noise levels). 

To avoid repetition, this introductory 

discussion of our analyses applies to all 

of the species listed in Table 31, given 

that many of the anticipated effects of 

this project on different marine mammal 

stocks are expected to be relatively 

similar in nature. Where there are 

meaningful differences between species 

or stocks in anticipated individual 

responses to activities, impact of 

expected take on the population due to 

differences in population status, or 

impacts on habitat, they are described 

independently in the analysis below. 

Pile driving activities associated with 

the project, as outlined previously, have 

the potential to disturb or displace 

marine mammals. Specifically, the 

specified activities may result in take, in 

the form of Level B harassment from 

underwater sounds generated by pile 

driving. Potential takes could occur if 

marine mammals are present in zones 

ensonified above the thresholds for 

Level B harassment, identified above, 

while activities are underway. No 

serious injury or mortality would be 

expected even in the absence of the 

proposed mitigation measures. 

A limited number of animals could 

experience Level A harassment in the 

form of PTS if they remain within the 

Level A harassment zone long enough 

during certain impact driving scenarios. 

However, the number of animal affected 

and the degree of injury is expected to 

be limited to, at most, mild PTS. 

Furthermore, the reproduction or 

survival of the individual animals is not 

likely to affected. It is expected that, if 

hearing impairments occurs, most likely 

the affected animal would lose a few dB 

in its hearing sensitivity, which in most 

cases is not likely to affect its survival 

and recruitment. 

HRCP’s proposed pile driving 

activities and associated impacts will 

occur within a limited portion of the 

confluence of the Chesapeake Bay area. 

Localized noise exposures produced by 

project activities may cause short-term 

behavioral modifications in affected 

cetaceans and pinnipeds. However, as 

described previously, the mitigation and 

monitoring measures are expected to 

further reduce the likelihood of injury 

as well as reduce behavioral 

disturbances. 

Effects on individuals that are taken 

by Level B harassment, on the basis of 

reports in the literature as well as 

monitoring from other similar activities, 

will likely be limited to reactions such 

as increased swimming speeds, 

increased surfacing time, or decreased 

foraging (if such activity were occurring) 

(e.g., Thorson and Reyff 2006). 

Individual animals, even if taken 

multiple times, will most likely move 

away from the sound source and be 

temporarily displaced from the areas of 

pile driving, although even this reaction 

has been observed primarily only in 

association with impact pile driving. 

The pile driving activities analyzed here 

are similar to, or less impactful than, 

numerous other construction activities 

conducted along the Atlantic coast, 

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, particularly as the project is 

located on a busy waterfront with high 

amounts of vessel traffic. 

As previously described, UMEs have 

been declared for Northeast pinnipeds 

(including harbor seal and gray seal) 

and Atlantic humpback whales. 

However, we do not expect takes 

proposed for authorization in this action 

to exacerbate or compound upon these 

ongoing UMEs. As noted previously, no 

injury, serious injury, or mortality is 

expect or proposed for authorization, 


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and Level A and Level B harassment 

takes of humpback whale, harbor seal 

and gray seal will be reduced to the 

level of least practicable adverse impact 

through the incorporation of the 

proposed mitigation measures. For the 

WNA stock of gray seal, the estimated 

stock abundance is 451,431 animals, 

including the Canadian portion of the 

stock (estimated 27,131 animals in the 

U.S. portion of the stock). Given that 

only 7 takes by Level B harassment and 

two takes by Level A harassment are 

proposed for this stock annually, we do 

not expect this proposed authorization 

to exacerbate or compound upon the 

ongoing UME. 

With regard to humpback whales, the 

UME does not yet provide cause for 

concern regarding population-level 

impacts. Despite the UME, the relevant 

population of humpback whales (the 

West Indies breeding population, or 

distinct population segment (DPS)) 

remains healthy. Prior to 2016, 

humpback whales were listed under the 

ESA as an endangered species 

worldwide. Following a 2015 global 

status review (Bettridge et al., 2015), 

NMFS established 14 DPSs with 

different listing statuses (81 FR 62259; 

September 8, 2016) pursuant to the ESA. 

The West Indies DPS, which consists of 

the whales whose breeding range 

includes the Atlantic margin of the 

Antilles from Cuba to northern 

Venezuela, and whose feeding range 

primarily includes the Gulf of Maine, 

eastern Canada, and western Greenland, 

was delisted. The status review 

identified harmful algal blooms, vessel 

collisions, and fishing gear 

entanglements as relevant threats for 

this DPS, but noted that all other threats 

are considered likely to have no or 

minor impact on population size or the 

growth rate of this DPS (Bettridge et al., 

2015). As described in Bettridge et al. 

(2015), the West Indies DPS has a 

substantial population size (i.e., 12,312 

(95 percent CI 8,688–15,954) whales in 

2004–05 (Bettridge et al. 2003)), and 

appears to be experiencing consistent 

growth. Further, NMFS is proposing to 

authorize no more than 35 takes by 

Level B harassment annually of 

humpback whale. 

For the WNA stock of harbor seals, 

the estimated abundance is 75,834 

individuals. The estimated M/SI for this 

stock (350) is well below the PBR 

(2,006). As such, the proposed Level B 

harassment takes of harbor seal are not 

expected to exacerbate or compound 

upon the ongoing UMEs. 

The project is also not expected to 

have significant adverse effects on 

affected marine mammals’ habitats. The 

project activities will not modify 

existing marine mammal habitat for a 

significant amount of time. The 

activities may cause some fish to leave 

the area of disturbance, thus temporarily 

impacting marine mammals’ foraging 

opportunities in a limited portion of the 

foraging range; but, because of the 

relatively small area of the habitat that 

may be affected (with no known 

particular importance to marine 

mammals), the impacts to marine 

mammal habitat are not expected to 

cause significant or long-term negative 

consequences. Furthermore, there are no 

known biologically important areas 

(BIAs), ESA-designated critical habitat, 

rookeries, or features of special 

significance for foraging or 

reproduction. 

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 serious injury or mortality is 

anticipated or authorized; 

• Authorized Level A harassment 

would be limited and of low degree; 

• The intensity of anticipated takes 

by Level B harassment is relatively low 

for all stocks; 

• The number of anticipated takes is 

very low for humpback whale, harbor 

porpoise, and gray seal; 

• The specified activity and 

associated ensonifed areas are very 

small relative to the overall habitat 

ranges of all species and do not include 

habitat areas of special significance; 

• The lack of anticipated significant 

or long-term negative effects to marine 

mammal habitat; and 

• The presumed efficacy of the 

mitigation measures in reducing the 

effects of the specified activity. 

Based on the analysis contained 

herein of the likely effects of the 

specified activity on marine mammals 

and their habitat, and taking into 

consideration the implementation of the 

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 section 101(a)(5)(A) 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. When the 

predicted number of individuals to be 

taken is fewer than one third of the 

species or stock abundance, the take is 

considered to be of small numbers. 

Additionally, other qualitative factors 

may be considered in the analysis, such 

as the temporal or spatial scale of the 

activities. 

The maximum annual take of take of 

humpback whale, harbor porpoise, 

harbor seal, and gray seal comprises less 

than one-third of the best available stock 

abundance estimate for each of these 

stocks (Table 31). The maximum 

number of animals authorized to be 

taken from these stocks would be 

considered small relative to the relevant 

stock’s abundances even if each 

estimated taking occurred to a new 

individual, which is an unlikely 

scenario. 

Three bottlenose dolphin stocks could 

occur in the project area: WNA Coastal 

Northern Migratory, WNA Coastal 

Southern Migratory, and NNCES stocks. 

Therefore, the estimated takes of 

bottlenose dolphin by Level B 

harassment would likely be portioned 

among these stocks. Based on the stocks’ 

respective occurrence in the area, NMFS 

estimated that there would be no more 

than 200 takes from the NNCES stock 

each year over the five-year period, 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 maximum number of individuals 

taken per year would likely comprise 

less than one-third of the best available 

population abundance estimate of either 

coastal migratory stock. 

Both the WNA Coastal Northern 

Migratory and WNA Coastal Southern 

Migratory 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 stocks it is 

unlikely that large segments of either 

stock would approach the project area 

and enter into the Chesapeake Bay. The 

majority of both stocks are likely to be 

found widely dispersed across their 

respective habitat ranges and unlikely to 

be concentrated in or near the 

Chesapeake Bay. 

Furthermore, the Chesapeake Bay and 

nearby offshore waters represent the 

boundaries of the ranges of each of the 

two coastal stocks during migration. The 

WNA Coastal Northern Migratory stock 


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occurs during warm water months from 

coastal Virginia, including the 

Chesapeake Bay to Long Island, New 

York. The stock migrates south in late 

summer and fall. During cold-water 

months, dolphins may occur in coastal 

waters from Cape Lookout, North 

Carolina, to the North Carolina/Virginia 

border. During January-March, the WNA 

Coastal Southern Migratory 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 JulyAugust, the stock is presumed to occupy 

coastal waters north of Cape Lookout, 

North Carolina, to Assateague, Virginia, 

including the Chesapeake Bay. There is 

likely some overlap between the 

northern and southern migratory stocks 

during spring and fall migrations, but 

the extent of overlap is unknown. 

The Chesapeake Bay and waters 

offshore of its mouth are located on the 

periphery of the migratory ranges of 

both coastal stocks (although during 

different seasons). Additionally, each of 

the migratory coastal stocks are likely to 

be located in the vicinity of the 

Chesapeake Bay for relatively short 

timeframes. Given the limited number 

of animals from each migratory coastal 

stock likely to be found at the seasonal 

migratory boundaries of their respective 

ranges, in combination with the short 

time periods (∼two months) animals 

might remain at these boundaries, it is 

reasonable to assume that takes are 

likely to occur to only a 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 (JulyAugust). Animals from 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 km2, 

while the NNCES stock occupies over 

8,000 km2 (LeBrecque et al., 2015). 

Given this large range, it is again 

unlikely that a preponderance of 

animals from the NNCES stock would 

depart the North Carolina estuarine 

system and travel to the northern extent 

of the stock’s range. However, recent 

evidence suggests that there is likely a 

small resident community of NNCES 

dolphins of indeterminate size that 

inhabits the Chesapeake Bay year-round 

(E. Patterson, NMFS, pers. comm.). 

Many of the dolphin observations in 

the Bay are likely repeated sightings of 

the same individuals. The PotomacChesapeake Dolphin Project has 

observed over 1,200 unique animals 

since observations began in 2015. Resightings 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, PotomacChesapeake Dolphin Project, pers. 

comm.). Similarly, using available 

photo-identification data, Engelhaupt et 

al. (2016) determined that specific 

individuals were often observed in close 

proximity to their original sighting 

locations and were observed multiple 

times in the same season or same year. 

Ninety-one percent of re-sighted 

individuals (100 of 110) in the study 

area were recorded less than 30 km from 

the initial sighting location. Multiple 

sightings of the same individual would 

considerably reduce the number of 

individual animals that are taken by 

Level B harassment. Furthermore, the 

existence of a resident dolphin 

population in the Bay would increase 

the percentage of dolphin takes that are 

actually re-sightings of the same 

individuals in any given year. 

In summary and as described above, 

the following factors primarily support 

our determination regarding the 

incidental take of small numbers of the 

affected stocks of bottlenose dolphin: 

• Potential bottlenose dolphin takes 

in the project area are likely to be 

allocated among three distinct stocks; 

• Bottlenose dolphin stocks in the 

project area have extensive ranges and 

it would be unlikely to find a high 

percentage of any one stock 

concentrated in a relatively small area 

such as the project area or the 

Chesapeake Bay; 

• The Chesapeake Bay represents the 

migratory boundary for each of the 

specified dolphin stocks and it would 

be unlikely to find a high percentage of 

any stock concentrated at such 

boundaries; and 

• Many of the takes would likely be 

repeats of the same animals and likely 

from a resident population of the 

Chesapeake Bay. 

Based on the analysis contained 

herein of the 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. 

Adaptive Management 

The regulations governing the take of 

marine mammals incidental to HRCP 

construction activities would contain an 

adaptive management component. The 

reporting requirements associated with 

this proposed rule are designed to 

provide NMFS with monitoring data 

from completed projects to allow 

consideration of whether any changes 

are appropriate. The use of adaptive 

management allows NMFS to consider 

new information from different sources 

to determine (with input from HRCP 

regarding practicability) on an annual or 

biennial basis if mitigation or 

monitoring measures should be 

modified (including additions or 

deletions). Mitigation measures could be 

modified if new data suggests that such 

modifications would have a reasonable 

likelihood of reducing adverse effects to 

marine mammals and if the measures 

are practicable. 

The following are some of the 

possible sources of applicable data to be 

considered through the adaptive 

management process: (1) Results from 

monitoring reports, as required by 

MMPA authorizations; (2) results from 

general marine mammal and sound 

research; and (3) any information which 

reveals that marine mammals may have 

been taken in a manner, extent, or 

number not authorized by these 

regulations or subsequent LOAs. 

Endangered Species Act 

Section 7(a)(2) of the Endangered 

Species Act of 1973 (ESA: 16 U.S.C. 

1531 et seq.) requires that each Federal 

agency insure that any action it 

authorizes, funds, or carries out is not 

likely to jeopardize the continued 

existence of any endangered or 

threatened species or result in the 

destruction or adverse modification of 

designated critical habitat. To ensure 

ESA compliance for the issuance of 

incidental take authorizations, NMFS 

consults internally whenever we 


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1632 Federal Register / Vol. 86, No. 5 / Friday, January 8, 2021 / Proposed Rules 

propose to authorize take for 

endangered or threatened species. 

No incidental take of ESA-listed 

species is proposed for authorization or 

expected to result from this activity. 

Therefore, NMFS has determined that 

formal consultation under section 7 of 

the ESA is not required for this action. 

Request for Information 

NMFS requests interested persons to 

submit comments, information, and 

suggestions concerning HRCP’s request 

and the proposed regulations (see 

ADDRESSES). All comments will be 

reviewed and evaluated as we prepare a 

final rule and make final determinations 

on whether to issue the requested 

authorization. This notice and 

referenced documents provide all 

environmental information relating to 

our proposed action for public review. 

Classification 

Pursuant to the procedures 

established to implement Executive 

Order 12866, the Office of Management 

and Budget has determined that this 

proposed rule is not significant. 

Pursuant to section 605(b) of the 

Regulatory Flexibility Act (RFA), the 

Chief Counsel for Regulation of the 

Department of Commerce has certified 

to the Chief Counsel for Advocacy of the 

Small Business Administration that this 

proposed rule, if adopted, would not 

have a significant economic impact on 

a substantial number of small entities. 

HRCP is the sole entity that would be 

subject to the requirements in these 

proposed regulations, and HRCP is not 

a small governmental jurisdiction, small 

organization, or small business, as 

defined by the RFA. Because of this 

certification, a regulatory flexibility 

analysis is not required and none has 

been prepared. 

Notwithstanding any other provision 

of law, no person is required to respond 

to nor shall a person be subject to a 

penalty for failure to comply with a 

collection of information subject to the 

requirements of the Paperwork 

Reduction Act (PRA) unless that 

collection of information displays a 

currently valid OMB control number. 

This proposed rule contains collectionof-information requirements subject to 

the provisions of the PRA. These 

requirements have been approved by 

OMB under control number 0648–0151 

and include applications for regulations, 

subsequent LOAs, and reports. 

List of Subjects in 50 CFR Part 217 

Administrative practice and 

procedure, Alaska, Endangered and 

threatened species, Exports, Fish, 

Imports, Indians, Labeling, Marine 

mammals, Oil and gas exploration, 

Penalties, Reporting and recordkeeping 

requirements, Seafood, Transportation, 

Wildlife. 

Dated: December 29, 2020. 

Samuel D. Rauch, III, 

Deputy Assistant Administrator for 

Regulatory Programs, National Marine 

Fisheries Service. 

For reasons set forth in the preamble, 

50 CFR part 217 is proposed to be 

amended as follows: 

PART 217—REGULATIONS 

GOVERNING THE TAKING AND 

IMPORTING OF MARINE MAMMALS 

■ 1. The authority citation for part 217 

continues to read as follows: 

Authority: 16 U.S.C. 1361 et seq., unless 

otherwise noted. 

■ 2. Add subpart W to read as follows: 

Subpart W—Taking and Importing Marine 

Mammals Incidental to Hampton Roads 

Connector Partners Construction at 

Norfolk, Virginia 

Sec. 

217.20 Specified activity and geographical 

region. 

217.21 Effective dates. 

217.22 Permissible methods of taking. 

217.23 Prohibitions. 

217.24 Mitigation requirements. 

217.25 Requirements for monitoring and 

reporting. 

217.26 Letters of Authorization. 

217.27 Renewals and modifications of 

Letters of Authorization. 

217.28–217.29 [Reserved] 

Subpart W—Taking and Importing 

Marine Mammals Incidental to 

Hampton Roads Connector Partners 

Construction at Norfolk, Virginia 

§ 217.20 Specified activity and 

geographical region. 

(a) Regulations in this subpart apply 

only to the Hampton Roads Connector 

Partners (HRCP) and those persons it 

authorizes or funds to conduct activities 

on its behalf for the taking of marine 

mammals that occurs in the areas 

outlined in paragraph (b) of this section 

and that occurs incidental to 

construction activities including marine 

structure maintenance, pile 

replacement, and select waterfront 

improvements at the Hampton Roads 

Bridge Tunnel Expansion Project 

(HRBT). 

(b) The taking of marine mammals by 

HRCP may be authorized in a Letter of 

Authorization (LOA) only if it occurs at 

the Hampton Roads Bridge Tunnel 

Expansion project location. 

§ 217.21 Effective dates. 

Regulations in this subpart are 

effective from [EFFECTIVE DATE OF 

THE FINAL RULE] to [DATE 5 YEARS 

AFTER EFFECTIVE DATE OF THE 

FINAL RULE]. 

§ 217.22 Permissible methods of taking. 

(a) Under an LOA issued pursuant to 

§§ 216.106 of this chapter and 217.26, 

the Holder of the LOA (hereinafter 

‘‘HRCP’’) may incidentally, but not 

intentionally, take marine mammals 

within the area described in § 217.20(b) 

by Level A and Level B harassment 

associated with construction activities, 

provided the activity is in compliance 

with all terms, conditions, and 

requirements of the regulations in this 

subpart and the applicable LOA. 

(b) [Reserved] 

§ 217.23 Prohibitions. 

(a) Except for the takings 

contemplated in § 217.22 and 

authorized by an LOA issued under 

§§ 216.106 of this chapter and 217.26, it 

is unlawful for any person to do any of 

the following in connection with the 

activities described in § 217.20: 

(1) Violate, or fail to comply with, the 

terms, conditions, and requirements of 

this subpart or a LOA issued under 

§§ 216.106 of this chapter and 217.26; 

(2) Take any marine mammal not 

specified in such LOA; 

(3) Take any marine mammal 

specified in such LOA in any manner 

other than as specified; 

(4) Take a marine mammal specified 

in such LOA if NMFS determines such 

taking results in more than a negligible 

impact on the species or stocks of such 

marine mammal; or 

(5) Take a marine mammal specified 

in such LOA if NMFS determines such 

taking results in an unmitigable adverse 

impact on the species or stock of such 

marine mammal for taking for 

subsistence uses. 

(b) [Reserved] 

§ 217.24 Mitigation requirements. 

(a) When conducting the activities 

identified in § 217.20(a), the mitigation 

measures contained in any LOA issued 

under §§ 216.106 of this chapter 

and 217.26 must be implemented. These 

mitigation measures shall include but 

are not limited to: 

(1) A copy of any issued LOA must be 

in the possession of HRCP, its 

designees, and work crew personnel 

operating under the authority of the 

issued LOA. 

(2) HRCP shall conduct briefings for 

construction supervisors and crews, the 

monitoring team, and HRCP staff prior 

to the start of all pile driving activity, 

and when new personnel join the work, 

in order to explain responsibilities, 

communication procedures, the marine 


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mammal monitoring protocol, and 

operational procedures. 

(3) For in-water heavy machinery 

work other than pile driving, if a marine 

mammal comes within 10 meters (m), 

HRCP shall cease operations and reduce 

vessel speed to the minimum level 

required to maintain steerage and safe 

working conditions. 

(4) For all pile driving activity, HRCP 

shall implement a minimum shutdown 

zone of a 10 m radius around the pile. 

If a marine mammal comes within or 

approaches the shutdown zone, such 

operations shall cease. 

(5) For all pile driving activity, HRCP 

shall implement shutdown zones with 

radial distances as identified in a LOA 

issued under §§ 216.106 of this chapter 

and 217.26. If a marine mammal comes 

within or approaches the shutdown 

zone, such operations shall cease. 

(6) HRCP deploy protected species 

observers (observers or PSOs) as 

indicated in its Marine Mammal 

Monitoring Plan approved by NMFS. 

(7) For all pile driving activities, 

between one and four observers shall be 

stationed at the best vantage points 

practicable to monitor for marine 

mammals and implement shutdown/ 

delay procedures. 

(8) Monitoring shall take place from 

30 minutes prior to initiation of pile 

driving activity through 30 minutes 

post-completion of pile driving activity. 

Pre-activity monitoring shall be 

conducted for 30 minutes to ensure that 

the shutdown zone is clear of marine 

mammals, and pile driving may 

commence when observers have 

declared the shutdown zone clear of 

marine mammals. In the event of a delay 

or shutdown of activity resulting from 

marine mammals in the shutdown zone, 

animals shall be allowed to remain in 

the shutdown zone (i.e., must leave of 

their own volition) and their behavior 

shall be monitored and documented. If 

a marine mammal is observed within 

the shutdown zone, a soft-start cannot 

proceed until the animal has left the 

zone or has not been observed for 15 

minutes. Monitoring shall occur 

throughout the time required to drive a 

pile. If in-water pile installation and 

removal work ceases for more than 30 

minutes, the pre-activity monitoring of 

the shutdown zones must commence. A 

determination that the shutdown zone is 

clear must be made during a period of 

good visibility (i.e., the entire shutdown 

zone and surrounding waters must be 

visible to the naked eye). 

(9) If a marine mammal approaches or 

enters the shutdown zone, all pile 

driving activities at that location shall 

be halted. In the event of a delay, the 

activity may not commence or resume 

until either the animal has voluntarily 

left and been visually confirmed beyond 

the shutdown zone or fifteen minutes 

have passed without re-detection of the 

animal. 

(10) Pile driving activity must be 

halted upon observation of either a 

species for which incidental take is not 

authorized or a species for which 

incidental take has been authorized but 

the authorized number of takes has been 

met, entering or within the harassment 

zone. 

(11) Should environmental conditions 

deteriorate such that marine mammals 

within the entire shutdown zone would 

not be visible (e.g., fog, heavy rain), 

HRCP shall delay pile driving and 

removal until observers are confident 

marine mammals within the shutdown 

zone could be detected. 

(12) Monitoring shall be conducted by 

trained observers, who shall have no 

other assigned tasks during monitoring 

periods. Trained observers shall be 

placed at the best vantage point(s) 

practicable to monitor for marine 

mammals and implement shutdown or 

delay procedures when applicable 

through communication with the 

equipment operator. HRCP shall adhere 

to the following additional observer 

qualifications: 

(i) Independent observers are 

required; 

(ii) At least one observer must have 

prior experience working as an observer; 

(iii) Other observers may substitute 

education (degree in biological science 

or related field) or training for 

experience; 

(iv) Where a team of three or more 

observers are required, one observer 

shall be designated as lead observer or 

monitoring coordinator. The lead 

observer must have prior experience 

working as an observer; and 

(v) HRCP must submit PSO CVs for 

approval by NMFS prior to the 

beginning of pile driving and drilling. 

(13) HRCP shall use soft start 

techniques for impact pile driving. Soft 

start for impact driving requires HRCP 

and those persons it authorizes to 

provide an initial set of three strikes at 

reduced energy, followed by a thirtysecond waiting period, then two 

subsequent reduced energy three-strike 

sets. Soft start shall 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. 

(14) HRCP shall employ bubble 

curtain systems during impact driving 

of steel piles except under conditions 

where the water depth is less than 20 

feet in depth. Bubble curtains must meet 

the following requirements: 

(i) The bubble curtain must distribute 

air bubbles around 100 percent of the 

piling perimeter for the full depth of the 

water column. 

(ii) 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. 

(iii) The bubble curtain must be 

operated such that there is proper 

(equal) balancing of air flow to all 

bubblers. 

(iv) HRCP shall require that 

construction contractors train personnel 

in the proper balancing of air flow to the 

bubblers and corrections to the 

attenuation device to meet the 

performance standards. This shall occur 

prior to the initiation of pile driving 

activities. 

(b) [Reserved] 

§ 217.25 Requirements for monitoring and 

reporting. 

(a) HRCP shall submit a Marine 

Mammal Monitoring Plan to NMFS for 

approval in advance of construction. 

(b) HRCP shall deploy observers as 

indicated in its approved Marine 

Mammal Monitoring Plan. 

(c) Observers shall be trained in 

marine mammal identification and 

behaviors. Observers shall have no other 

construction-related tasks while 

conducting monitoring. 

(d) HRCP shall monitor the Level B 

harassment zones and Level A 

harassment zones extending beyond the 

designated shutdown zones to the 

extent practicable. 

(e) HRCP shall monitor the shutdown 

zones during all pile driving and 

removal activities. 

(f) HRCP shall submit a draft annual 

monitoring report to NMFS within 90 

work days of the completion of annual 

marine mammal monitoring. The report 

must detail the monitoring protocol and 

summarize the data recorded during 

monitoring. If no comments are received 

from NMFS within 30 days, the draft 

report will constitute the final report. If 

comments are received, a final report 

addressing NMFS comments must be 

submitted within 30 days after receipt of 

comments. Specifically, the report must 

include: 

(1) Dates and times (begin and end) of 

all marine mammal monitoring. 

(2) 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). 


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(3) Environmental conditions during 

monitoring periods (at beginning and 

end of PSO shift and whenever 

conditions change significantly), 

including Beaufort sea state and any 

other relevant weather conditions 

including cloud cover, fog, sun glare, 

and overall visibility to the horizon, and 

estimated observable distance (if less 

than the harassment zone distance). 

(4) 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. 

(5) Age and sex class, if possible, of 

all marine mammals observed. 

(6) PSO locations during marine 

mammal monitoring. 

(7) 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). 

(8) 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. 

(9) Number of marine mammals 

detected within the harassment zones, 

by species. 

(10) 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. 

(11) 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. 

(g) 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) (301–427–8401), NMFS and to 

the Greater Atlantic Region New 

England/Mid-Atlantic Regional 

Stranding Coordinator as soon as 

feasible. If the death or injury was 

clearly caused by the specified activity, 

HRCP must immediately cease the 

specified activities until NMFS is able 

to review the circumstances of the 

incident and determine what, if any, 

additional measures are appropriate to 

ensure compliance with the terms of the 

authorization. HRCP must not resume 

their activities until notified by NMFS. 

The report must include the following 

information: 

(1) Time, date, and location (latitude/ 

longitude) of the first discovery (and 

updated location information if known 

and applicable); 

(2) Species identification (if known) 

or description of the animal(s) involved; 

(3) Condition of the animal(s) 

(including carcass condition if the 

animal is dead); 

(4) Observed behaviors of the 

animal(s), if alive; 

(5) If available, photographs or video 

footage of the animal(s); and 

(6) General circumstances under 

which the animal was discovered. 

§ 217.26 Letters of Authorization. 

(a) To incidentally take marine 

mammals pursuant to the regulations in 

this subpart, HRCP must apply for and 

obtain an LOA. 

(b) An LOA, unless suspended or 

revoked, may be effective for a period of 

time not to exceed the expiration date 

of the regulations in this subpart. 

(c) If an LOA expires prior to the 

expiration date of the regulations in this 

subpart, HRCP may apply for and obtain 

a renewal of the LOA. 

(d) In the event of projected changes 

to the activity or to mitigation and 

monitoring measures required by an 

LOA, HRCP must apply for and obtain 

a modification of the LOA as described 

in § 217.27. 

(e) The LOA shall set forth the 

following information: 

(1) Permissible methods of incidental 

taking; 

(2) Means of effecting the least 

practicable adverse impact (i.e., 

mitigation) on the species, its habitat, 

and on the availability of the species for 

subsistence uses; and 

(3) Requirements for monitoring and 

reporting. 

(f) Issuance of the LOA shall be based 

on a determination that the level of 

taking will be consistent with the 

findings made for the total taking 

allowable under the regulations in this 

subpart. 

(g) Notice of issuance or denial of an 

LOA shall be published in the Federal 

Register within thirty days of a 

determination. 

§ 217.27 Renewals and modifications of 

Letters of Authorization. 

(a) An LOA issued under §§ 216.106 

of this chapter and 217.26 for the 

activity identified in § 217.20(a) shall be 

renewed or modified upon request by 

the applicant, provided that: 

(1) The proposed specified activity 

and mitigation, monitoring, and 

reporting measures, as well as the 

anticipated impacts, are the same as 

those described and analyzed for the 

regulations in this subpart; and 

(2) NMFS determines that the 

mitigation, monitoring, and reporting 

measures required by the previous LOA 

under the regulations in this subpart 

were implemented. 

(b) For LOA modification or renewal 

requests by the applicant that include 

changes to the activity or the mitigation, 

monitoring, or reporting that do not 

change the findings made for the 

regulations in this subpart or result in 

no more than a minor change in the 

total estimated number of takes (or 

distribution by species or years), NMFS 

may publish a notice of proposed LOA 

in the Federal Register, including the 

associated analysis of the change, and 

solicit public comment before issuing 

the LOA. 

(c) An LOA issued under §§ 216.106 

of this chapter and 217.26 for the 

activity identified in § 217.20(a) may be 

modified by NMFS under the following 

circumstances: 

(1) HRCP may modify (including 

augment) the existing mitigation, 

monitoring, or reporting measures (after 

consulting with NMFS regarding the 

practicability of the modifications) if 

doing so creates a reasonable likelihood 

of more effectively accomplishing the 

goals of the mitigation and monitoring 

set forth in the regulations in this 

subpart. 

(i) Possible sources of data that could 

contribute to the decision to modify the 

mitigation, monitoring, or reporting 

measures in a LOA: 

(A) Results from HRCP’s monitoring 

from previous years. 

(B) Results from other marine 

mammal and/or sound research or 

studies. 

(C) Any information that reveals 

marine mammals may have been taken 

in a manner, extent or number not 

authorized by the regulations in this 

subpart or subsequent LOAs. 

(ii) If, through adaptive management, 

the modifications to the mitigation, 

monitoring, or reporting measures are 

substantial, NMFS will publish a notice 

of proposed LOA in the Federal 

Register and solicit public comment. 

(2) If NMFS determines that an 

emergency exists that poses a significant 

risk to the well-being of the species or 

stocks of marine mammals specified in 

a LOA issued pursuant to §§ 216.106 of 

this chapter and 217.26, a LOA may be 

modified without prior notice or 

opportunity for public comment. Notice 

would be published in the Federal 

Register within thirty days of the action. 

§ § 217.28–217.29 [Reserved] 

[FR Doc. 2020–29125 Filed 1–7–21; 8:45 am] 

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