[Federal Register Volume 86, Number 62 (Friday, April 2, 2021)]
[Rules and Regulations]
[Pages 17458-17492]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-06132]



[[Page 17457]]

Vol. 86

Friday,

No. 62

April 2, 2021

Part II





Department of Commerce





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National Oceanic and Atmospheric Administration





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50 CFR Part 217





Taking Marine Mammals Incidental to the Hampton Roads Bridge Tunnel 
Expansion Project in Norfolk, Virginia; Final Rule

  Federal Register / Vol. 86 , No. 62 / Friday, April 2, 2021 / Rules 
and Regulations  

[[Page 17458]]



DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

50 CFR Part 217

[Docket No. 210318-0058]
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: Final rule; notification of issuance of Letters of 
Authorization.

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SUMMARY: NMFS, upon request of the Hampton Roads Connector Partners 
(HRCP), hereby issues regulations to govern the unintentional taking of 
marine mammals incidental to construction activities associated with 
the Hampton Roads Bridge Tunnel Expansion Project (HRBT) in Norfolk, 
Virginia, over the course of five years (2021-2026). These regulations, 
which allow for the issuance of Letters of Authorization (LOA) for the 
incidental take of marine mammals during the described activities and 
specified timeframes, prescribe the permissible methods of taking and 
other means of effecting the least practicable adverse impact on marine 
mammal species or stocks and their habitat, as well as requirements 
pertaining to the monitoring and reporting of such taking.

DATES: Effective from April 2, 2021 through April 1, 2026.

ADDRESSES: A copy of HRCP's application and supporting documents, as 
well as a list of the references cited in this document, may be 
obtained online at: https://www.fisheries.noaa.gov/action/incidental-take-authorization-hampton-roads-bridge-tunnel-expansion-project-hampton-0. In case of problems accessing these documents, please call 
the contact listed below.

FOR FURTHER INFORMATION CONTACT: Robert Pauline, Office of Protected 
Resources, NMFS, (301) 427-8401.

SUPPLEMENTARY INFORMATION: 

Purpose and Need for Regulatory Action

    We received an application from the HRCP requesting five-year 
regulations and authorization to take multiple species of marine 
mammals. This rule establishes 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 the HRCP's construction activities 
associated with the HRBT. The HRBT is a major road transportation 
infrastructure project 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 purpose of 
the project is to address severe traffic congestion at the existing 
HRBT crossing by increasing traffic capacity and upgrading lanes.

Legal Authority for the 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 Mitigation Measures 
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 final rule 
containing five-year regulations, and for any subsequent LOAs. As 
directed by this legal authority, this final rule contains mitigation, 
monitoring, and reporting requirements.

Summary of Major Provisions Within the Final Rule

    Following is a summary of the major provisions of these regulations 
regarding HRCP's construction activities. These measures include:
     Shutdown of construction activities under certain 
circumstances to minimize 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; and
     Use of bubble curtains during impact driving of steel 
piles in appropriate circumstances.

Background

    The MMPA prohibits the ``take'' of marine mammals, with certain 
exceptions. Sections 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361 
et seq.) direct the Secretary of Commerce (as delegated to NMFS) to 
allow, upon request, the incidental, but not intentional, taking of 
small numbers of marine mammals by U.S. citizens who engage in a 
specified activity (other than commercial fishing) within a specified 
geographical region if certain findings are made and either regulations 
are issued or, if the taking is limited to harassment, a notice of a 
proposed incidental take authorization may be provided to the public 
for review.
    Authorization for incidental takings shall be granted if NMFS finds 
that the taking will have a negligible impact on the species or 
stock(s) and will not have an unmitigable adverse impact on the 
availability of the species or stock(s) for taking for subsistence uses 
(where relevant). Further, NMFS must prescribe the permissible methods 
of taking and other ``means of effecting the least practicable adverse 
impact'' on the affected species or stocks and their habitat, paying 
particular attention to rookeries, mating grounds, and areas of similar 
significance, and on the availability of the species or stocks for 
taking for certain subsistence uses (referred to in shorthand as 
``mitigation''); and requirements pertaining to the mitigation, 
monitoring and reporting of the takings are set forth. The definitions 
of all applicable MMPA statutory terms cited above are included in the 
relevant sections below.

Summary of Request

    On 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 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. The proposed rule was subsequently published 
in the Federal Register on January 8, 2021 (86 FR 1588) and requested 
comments and information from the public. Please see Comments and 
Responses, below.

[[Page 17459]]

    HRCP previously applied for an incidental harassment authorization 
(IHA) to cover initial in-water pile driving work. That IHA was issued 
on July 10, 2020 (85 FR 48153; August 10, 2020), and is effective until 
July 9, 2021. Information related to this previous IHA may be found 
online at: https://www.fisheries.noaa.gov/action/incidental-take-authorization-hampton-roads-bridge-tunnel-expansion-project-hampton-norfolk. To date, HRCP has adhered to all mitigation, monitoring, and 
reporting requirements and has not exceed authorized numbers of take.
    HRCP proposed to conduct in-water construction activities, 
including pile installation and removal, and requested authorization to 
take five species of marine mammals by Level A and Level B harassment. 
Neither HRCP nor NMFS expects serious injury or mortality to result 
from this activity, and none is authorized. The regulations are 
effective for five years (2021-2026).

Description of Activity

Overview

    HRCP is planning 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 and 
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 HRBT project will require extensive pile installation and pile 
removal activities. Pile installation methods will include impact and 
vibratory driving, jetting, and down-the-hole (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 project 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 regulations are 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 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 five years, 
based on a 6-day work week for an estimated total of 1,560 days.
    HRCP plans to conduct work during daylight hours. However, 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 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. (see Figures 1-1 and 2-1 in HRCP's application). For 
additional detail regarding the specified geographic region, please see 
our Proposed Rule (86 FR 1588; January 8, 2021) and Section 2 of HRCP's 
application. A map of the HRBT Project Area is provided in Figure 1 
below and Figures 1-1 and 2-1 in HRCP's application.

Detailed Description of Specific Activity

    The planned 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.
    Pile installation and removal would occur at North Trestle, North 
Island, South Island, South Trestle, Willoughby Spit, and Willoughby 
Bay (refer to Figure 1-1 in the application). Table 1 below identifies 
the various project design segments where in-water marine construction 
activities are planned that have the potential to affect marine 
mammals. HRCP plans to install up to 6,798 piles including 24- to 60-
inch steel pipe piles, 24- to 54-inch concrete piles, 16-inch timber 
piles, and sheet piles. This would be done by a variety of methods 
including use of vibratory hammer, impact hammer, DTH hammer, and/or 
jetting. HRCP would remove up to 4,728 piles including 24- to 42-inch 
steel pipe piles, sheet piles, and 16-inch timber piles using a 
vibratory hammer, direct pull or by cutting them below the mudline. 
HRCP plans on using multiple hammers concurrently to install and remove 
piles. Tables 2 through Table 6 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. A detailed description of HRCP's planned activities was 
provided in our notice of proposed rulemaking (86 FR 1588; January 8, 
2021) and is not repeated here. No changes have been made to the 
specified activities described therein.

             Table 1--HRBT Expansion Project Design Segments
------------------------------------------------------------------------
                                                           Construction
         Project design segment  number and name               area
------------------------------------------------------------------------
Segment 1a (Hampton)....................................               1
Segment 1b (North Trestle-Bridges) \1\..................               2
Segment 2a (Tunnel) \1\.................................               3
Segment 3a (South Trestle-Bridge) \1\...................               2
Segment 3b (Willoughby Spit) \1\........................               4
Segment 3c (Willoughby Bay Trestle-Bridges) \1\.........               2
Segment 3d (4th View Street Interchange)................               4
Segment 4a (Norfolk-Navy)...............................               4
Segment 5a (I-564 Interchange)..........................               4
------------------------------------------------------------------------
\1\ Indicates segment includes in-water construction activities.


[[Page 17460]]


                                                  Table 2--Numbers and Types of Piles To Be Installed and Removed During LOA Year One for Each
                                                                               HRBT Project Component and Segment
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                                                                                                            Average
                                                               Total      Total                 Number of  down-the-  Number  of   Average   Approximate   Number of    Estimated     Number of
                                       Pile size/type and    number of  number of   Embedment     piles       hole       piles    vibratory   number of    piles per  total number     days of
         Project component                  material         piles  to  piles  to     length    down-the-   duration   vibrated/   duration     impact      day per    of hours of  installation
                                                                 be         be        (feet)       hole     per pile   hammered    per pile    strikes      hammer    installation   and removal
                                                             installed   removed                           (minutes)              (minutes)    per pile                and removal
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                   North Trestle (Segment 1b)
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Permanent Piles....................  54-inch Concrete              188          0          140  .........  .........         188  .........        2,100           1           376           188
                                      Cylinder Pipe.
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
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                                                                                    North Island (Segment 2a)
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Hampton Creek Approach Channel       Existing, 36-inch               1          1  ...........  .........  .........           1         50  ...........           1             2             1
 Marker.                              Steel Pipe.
North Island Expansion.............  AZ 700-26 Steel Sheet.        176        176           40  .........  .........         352         30  ...........          10           176            35
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                                                                                   Willoughby Bay (Segment 3c)
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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              402          0          140  .........  .........         402  .........        2,100           1           804           402
                                      Square Pipe.
Casing.............................  42-inch Steel Pipe....        240        240           60  .........  .........         480         30  ...........           6           160            80
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                                                                                  Willoughby Spit (Segment 3b)
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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
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                                                                                   South Trestle (Segment 3a)
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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              252          0          140  .........  .........         252  .........        2,100           1           504           252
                                      Cylinder Pipe.
Casing.............................  60-inch Steel Pipe....         65          0           60         65        120  ..........  .........  ...........           3           130            22
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                                                                                    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,            82          0           85          8        120          74         60           40           6            82            14
                                      Concrete Filled.
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
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* CCA = Chromated Copper Arsenate; MOT = Maintenance of Traffic; TBM = Tunnel Boring Machine.


                                 Table 3--Numbers and Types of Piles To Be Installed and Removed During LOA Year Two for Each HRBT Project Component and Segment
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                                                                                                            Average
                                                               Total      Total                 Number of  down-the-  Number  of   Average   Approximate   Number of    Estimated     Number of
                                       Pile size/type and    number of  number of   Embedment     piles       hole       piles    vibratory   number of    piles per  total number     days of
         Project component                  material         piles  to  piles  to     length    down-the-   duration   vibrated/   duration     impact      day per    of hours of  installation
                                                                 be         be        (feet)       hole     per pile   hammered    per pile    strikes      hammer    installation   and removal
                                                             installed   removed                           (minutes)              (minutes)    per pile                and removal
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                   North Trestle (Segment 1b)
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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
Permanent Piles....................  54-inch, Concrete             102          0          140  .........  .........         102  .........        2,100           1           204           102
                                      Cylinder Pipe.
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                                                                                    North Island (Segment 2a)
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North Island Abutment..............  AZ 700-19 Steel Sheet.         96          0           20  .........  .........          96         30  ...........          10            48            10
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                                                                                   Willoughby Bay (Segment 3c)
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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              102          0          140  .........  .........         102  .........        2,100           1           204           102
                                      Square Pipe.

[[Page 17461]]

 
Casing.............................  42-inch Steel Pipe....         60         60           60  .........  .........         120         30  ...........           6            60            20
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                                                                                   South Trestle (Segment 3a)
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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              168          0          140  .........  .........         168  .........        2,100           1           336           168
                                      Cylinder Pipe.
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                    South Island (Segment 2a)
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Settlement Reduction Piles.........  24-inch Steel Pipe,           370          0           85  .........  .........         370         60           40           6           370            62
                                      Steel.
Deep Foundation Piles..............  30-inch Steel Pipe,           425          0           85         42        120         383         60           40           6           425            71
                                      Concrete Filled.
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
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
* CCA = Chromated Copper Arsenate; MOT = Maintenance of Traffic; TBM = Tunnel Boring Machine.


                                                 Table 4--Numbers and Types of Piles To Be Installed and Removed During LOA Year Three for Each
                                                                               HRBT Project Component and Segment
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                            Average
                                                               Total      Total                 Number of  down-the-  Number  of   Average   Approximate   Number of    Estimated     Number of
                                       Pile size/type and    number of  number of   Embedment     piles       hole       piles    vibratory   number of    piles per  total number     days of
         Project component                  material         piles  to  piles  to     length    down-the-   duration   vibrated/   duration     impact      day per    of hours of  installation
                                                                 be         be        (feet)       hole     per pile   hammered    per pile    strikes      hammer    installation   and removal
                                                             installed   removed                           (minutes)              (minutes)    per pile                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             187          0          140  .........  .........         187  .........        2,100           1           374           187
                                      Cylinder Pipe.
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
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              196          0          140  .........  .........         196  .........        2,100           1           392           196
                                      Cylinder Pipe.
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                    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
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
* CCA = Chromated Copper Arsenate; MOT = Maintenance of Traffic; TBM = Tunnel Boring Machine.


                                Table 5--Numbers and Types of Piles To Be Installed and Removed During LOA Year Four for Each HRBT Project Component and Segment
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                            Average
                                                               Total      Total                 Number of  down-the-  Number  of   Average   Approximate   Number of    Estimated     Number of
                                       Pile size/type and    number of  number of   Embedment     piles       hole       piles    vibratory   number of    piles per  total number     days of
         Project component                  material         piles  to  piles  to     length    down-the-   duration   vibrated/   duration     impact      day per    of hours of  installation
                                                                 be         be        (feet)       hole     per pile   hammered    per pile    strikes      hammer    installation   and removal
                                                             installed   removed                           (minutes)              (minutes)    per pile                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              85          0          140  .........  .........          85  .........        2,100           1           170            85
                                      Cylinder Pipe.

[[Page 17462]]

 
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              194          0          140  .........  .........         194  .........        2,100           1           388           194
                                      Cylinder Pipe.
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                    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
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                              Average
                                                                 Total      Total                 Number of  down-the-  Number  of   Average   Approximate   Number of   Estimated
                                         Pile size/type and    number of  number of   Embedment     piles       hole       piles    vibratory   number of    piles per     total      Number of
          Project component                   material         piles  to  piles  to     length    down-the-   duration   vibrated/   duration     impact      day per    number of     days of
                                                                   be         be        (feet)       hole     per pile   hammered    per pile    strikes      hammer      hours of     removal
                                                               installed   removed                           (minutes)              (minutes)    per pile                 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
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                    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           36            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
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                             Estimated       Estimated    Average  down-      Average       Number  of
                                                                             number of       number of       the-hole        vibratory    piles  per day
        Project component/location           Pile size/type and material     template        template      duration  per   duration per   per  component
                                                                            piles to be     piles to be        pile        template pile    (install and
                                                                             installed        removed        (minutes)       (minutes)       removal)
--------------------------------------------------------------------------------------------------------------------------------------------------------
North Trestle Permanent Piles.............  54-inch Concrete Cylinder                750             750  ..............               5               8
                                             Pipe.
South Trestle Permanent Piles.............  54-inch Concrete Cylinder              1,080           1,080  ..............               5               8
                                             Pipe.
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             676             676             120               5              16
                                             Filled.

[[Page 17463]]

 
South Island Settlement Reduction Piles...  24-inch Steel Pipe..........             526             526  ..............               5              16
                                                                         -------------------------------------------------------------------------------
Estimated Total Template Pile Driving       ............................           3,774           3,774  ..............  ..............  ..............
 Actions.
                                                                         --------------------------------
Total number of Temporary Template Pile     ............................               7,548
 Driving action.
--------------------------------------------------------------------------------------------------------------------------------------------------------
* The piles at Willoughby Spit will be temporary piles for the two temporary piers being constructed to allow barge access; however, these piles will be
  using a template for installation.

    Mitigation, monitoring, and reporting measures are described in 
detail later in this document (please see Mitigation and Monitoring and 
Reporting).

Comments and Responses

    We published a Proposed Rule in the Federal Register on January 8, 
2021 (86 FR 1588). During the 30-day comment period, we received a 
letter from the Marine Mammal Commission (Commission), and comments 
from two members of the general public. All substantive recommendations 
are responded to here. The comments are available online at: https://www.fisheries.noaa.gov/action/incidental-take-authorization-hampton-roads-bridge-tunnel-expansion-project-hampton-0.
    Comment 1: The Commission recommended that NMFS publish a corrected 
notice in the Federal Register that includes, at a minimum, the dates 
and the correct number(s) of days within a year the activities are 
expected to occur, the correct input parameters for estimating the 
extents of the Level A harassment zones, the correct proposed shut-down 
zones, and the revised numbers of Level A and B harassment takes for 
Year 5 and provide a 30-day comment period from when the corrected 
notice publishes. The Commission further recommended that NMFS refrain 
from publishing any final rule until the correct shut-down zones have 
been made available for the public to provide meaningful comments 
during a 30-day comment period, which the Commission asserted would 
fulfill NMFS's requirements under the Administrative Procedure Act.
    Response: NMFS does not agree with the Commission and does not 
adopt the recommendation. NMFS disagrees that the information presented 
in association with the proposed rule was insufficient to facilitate 
public review and comment. NMFS agrees that minor formatting issues 
occurred in some tables, likely due to their size and complexity. A 
number of the Commission's suggested corrections are, for the most 
part, differences of opinion on how available data should be applied to 
our analysis and, in each case, we have presented reasons why we 
disagree with specific recommendations. If we did agree that there 
actually was an error or that the Commission's logic is more 
appropriate to implement, we have made the recommended changes. We note 
many of the recommendations by the Commission are detail-oriented and, 
in NMFS' view, do not provide additional conservation value or 
meaningfully influence any of the analyses underlying the necessary 
findings. NMFS is confident that our negligible impact and least 
practicable adverse impact determinations are valid, and we note that 
the Commission did not provide any information to the contrary. 
Overall, there are no substantial changes or new information that would 
lead us to reach any other conclusions regarding the impact to marine 
mammals. Any increase in take numbers resulted from, NMFS increasing 
the number of Level A and B harassment takes for Year 5 by assuming 
that construction would take the full year instead of a partial year 
(312 work days instead of 181 work days). For these reasons, NMFS is 
not republishing a notice of proposed rulemaking.
    Comment 2: The Commission recommended that NMFS should determine 
the appropriate timeframes over which sound exposure levels should be 
accumulated when estimating the extents of the Level A harassment 
zones. The Commission also recommended that NMFS prioritize resolving 
this issue in the near future and consider incorporating animat 
modeling into its user spreadsheet.
    Response: NMFS generally concurs with this recommendation and has 
prioritized the issue. NMFS is also exploring the applicability of 
utilizing animat models.
    Comment 3: The Commission recommended that NMFS (1) refrain from 
using any assumed reductions in the operational parameters or presumed 
residency time when estimating the extents of the Level A harassment 
zones, (2) verify that a maximum of only one 54-inch concrete pile can 
be installed at a given location on a given day and, if the impact 
hammers at North and South Trestle would be in close proximity (500-700 
m), assume that the Level A harassment zones would overlap and two 
piles would be installed per day rather than one, and (3) re-estimate 
the extents of the Level A harassment zones for all scenarios for 
HRCP's activities, re-estimate the numbers of Level A harassment takes 
as necessary, and revise the shut-down zones accordingly in the 
preamble to and the final rule.
    Response: The Commission repeatedly asserts that NMFS' assumptions 
in evaluating potential Level A harassment are ``arbitrary,'' and 
states that NMFS' assumptions are made in an ``effort to reduce the 
size of the Level A harassment zones.'' NMFS disagrees. Although we 
acknowledge the general lack of data available to inform a species- and 
location-specific understanding of likely individual residence time in 
the vicinity of a construction project, the approach espoused by the 
Commission, in which individual animals are assumed to remain in the 
construction area for extended periods of time, would be unnecessarily 
precautionary in many cases. As is typical for marine construction 
areas, the affected areas considered for this activity are located in 
urbanized and/or industrialized settings, encompass generally degraded 
habitat relative to other nearby available habitat, and do not include 
areas of particular importance for foraging or

[[Page 17464]]

other important behaviors. In this context, and given what should be 
considered generally to be aversive stimulus (i.e., noise from 
construction activity), it is unrealistic to assume that individual 
animals remain present for extended periods of time. Therefore, NMFS 
makes reasonable assumptions to more realistically represent the likely 
potential for Level A harassment to occur.
    For purposes of estimated take by Level A harassment, NMFS assumed 
that the number of piles, and therefore pile strikes, installed on a 
given day was 50 percent of the total that was actually planned. 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 during the entire installation/removal process 
involving multiple piles throughout a given day. To provide a more 
realistic estimate of take by Level A harassment, NMFS assumed that an 
animal would occur within the injury zone for 50 percent of the driving 
time, (which for purposes of zone size calculation equates to 50 
percent of the piles and strikes planned for installation).
    HRCP also plans to install a single 54-inch concrete pile at a 
given driving location per day. Since the largest estimated Level A 
harassment isopleth is 420 m (i.e. low-frequency cetaceans) and the 
North and South Trestle are a minimum of 500 m apart, the Level A 
harassment zones associated with each site would not overlap.
    Given the information provided above, there is no reason for NMFS 
to re-estimate the extents of the Level A harassment zones, re-estimate 
the numbers of Level A harassment takes or revise the shut-down zones.
    Comment 4: The Commission recommended that NMFS (1) fully describe 
the regression analysis or extrapolation method (including the actual 
source level data points, associated references, and type of 
regression) used for estimating the SELs-s source level for DTH pile 
installation of 60-inch piles, (2) explain why such a method was not 
used for SPLpeak source levels and why NMFS believes that an SPLpeak 
source level would be the same for 30-, 36-, and 42-inch piles as 60-
inch piles, and (3) ensure appropriate review of the regression 
analysis for the SELs-s source level for 60-inch piles and 
justification for the SPLpeak source level for 60-inch piles before 
publishing any final rule, and (4) ensure appropriate review of all 
regression analyses, extrapolation methods, and proxy source levels for 
DTH pile installation for all related incidental take authorizations; 
and (5) specify when it uses source levels associated with different 
pile types or sizes as proxies and what the differences are.
    Response: In summary, NMFS ran regressions in the R programming 
language (version 3.5.1) using the R Commander Graphical User 
Interface. Data were average source levels from recordings of single 
piles and available covariates (e.g., water depth, pile depth, hole 
size, distance of sound source measurement) where NMFS had access to 
both published and unpublished DTH monitoring data. The Generalized 
Linear Model routine in R Commander was used to assess the fit of 
linear and non-linear multiple regression models of the data. Model 
assumptions were assessed graphically and mathematically and the best 
fit of models that fit statistical assumptions and retained 
statistically significant covariates was chosen mathematically. The 
best fit model was used to calculate the source level for the 
extrapolated hole size. The calculated source level was then rounded to 
the next highest integer decibel for use in this action. The 
extrapolation technique and software packages employed by NMFS and 
described below are commonly used and widely accepted by the scientific 
community.
    NMFS did not use SPLpeak source levels when calculating zones as 
the SEL metric typically results in largest isopleths. Using peak 
levels in situations when there are a large number of strikes per day 
will not provide the largest harassment isopleths. NMFS has reviewed 
the DTH data and methodologies that were utilized and that were used in 
developing our interim guidance and determined they are the best 
available.
    In Table 11 in the notice of proposed rule, NMFS specified the pile 
sizes of the proxies it used for impact and vibratory driving. Table 11 
in this notice has been revised to display the different pile sizes 
that were used as proxies for DTH installation. NMFS will include this 
type of information as appropriate in future ITAs.
    Comment 5: The Commission recommended that NMFS (1) have its 
experts in underwater acoustics and bioacoustics review and finalize as 
soon as possible, its recommended proxy source levels for impact pile 
driving of the various pile types and sizes, (2) compile and analyze 
the source level data for vibratory pile driving of the various pile 
types and sizes in the near term, and (3) ensure action proponents use 
consistent and appropriate proxy source levels in all future 
rulemakings and proposed incidental harassment authorizations.
    Response: NMFS concurs with the Commission's recommendation and has 
prioritized these efforts.
    Comment 6: The Commission recommended that NMFS refrain from using 
the 7-dB source level reduction factor for far-field impacts (>100 m) 
and consult with acousticians regarding the appropriate source level 
reduction factor, if any, to use to minimize far-field effects on 
marine mammals.
    Response: NMFS does not agree with the Commission's assessment on 
bubble curtain efficacy that is based on near- and far-distance 
(referred as ``near-field'' and ``far-field'' by the Commission). The 
Commission noted information provided in Illingworth and Rodkin (2012) 
suggesting that, in some cases, sound level reductions in the far field 
may be less (4 to 5 dB reduction approximately 120-750 m from the 
source). Although the measured levels at far-distances (i.e., >100 m) 
showed less differences (e.g., 4-5 dB) from those that were measured at 
near source at 10 m (e.g., 8 dB), this is likely due to propagation 
effects that some of the sediment-borne acoustic energy that was not 
attenuated by the bubble curtain re-emerged into the water-column at 
much further distances. However, this information should not be used to 
suggest that a different noise level reduction needs to be used for 
long-distance (Level B harassment distance) impact assessment. Since 
the applicant used a conservative practical spreading approximation of 
propagation loss (i.e., 15 log (r)), acoustic energy that is lost due 
to boundary refraction and reflection is not considered in determining 
the impact distances, and this loss is in addition to the practical 
spreading. Therefore, the small differences at far-distances between 
with and without bubble curtains indicates that the bubble curtain is 
less effective in attenuating additional acoustic energy beyond that 
within the water column.
    Comment 7: NMFS used the average of average daily counts of seals 
(13.6) at the Chesapeake Bay Bridge Tunnel (CBBT) to estimate take for 
the HRBT project. The Commission recommended that NMFS re-estimate the 
number of Level B harassment takes of harbor seals based on the maximum 
daily count (45 seals) at the CBBT haul-out sites added to the 
percentage of the Eastern Shore haul-out sites average of the daily 
average count (18.3 seals) that occur in the Chesapeake Bay (36 
percent). This equates to an additional 7 seals per day for a daily 
total of 52 takes.

[[Page 17465]]

    Response: There are no known seal haul outs in the James River and 
within the Core Monitoring Area which is the area expected to be 
ensonified during most of the pile installation and removal activities. 
The CBBT is over 9 nautical miles and the Eastern Shore is 
approximately 24 nautical miles from the HRBT. Sightings of seals at 
the HRBT are low and occur only during winter months, November through 
April. The HRBT project is currently operating under an IHA that 
authorizes 2,184 takes by Level A and Level B harassment combined for 
harbor seals. The analysis for the IHA used an average take of 13.6 
harbor seals per day. The project began pile installation in September 
and no seals have been sighted during 5 months of construction under 
the Project's Marine Mammal Monitoring and Mitigation Program. The 
estimated 14 harbor seals per day is based on Jones et al. (2020), 
concurring that activities at HRBT would not take the maximum daily 
harbor seals sighted at CBBT (45 animals). Based on current sighting 
data and previous sighting trends, 13.6 harbor seals per day is an 
appropriate estimate which results in 2,122 combined takes by Level A 
and Level B harassment per year. NMFS does not concur with the 
Commission's recommendation.
    Comment 8: The Commission recommended that NMFS (1) re-estimate the 
numbers of Level A harassment takes for each species and each of the 
first four years of activities based on the percentages of days in 
which the Level A harassment zones exceed the shut-down zones and (2) 
authorize the revised numbers of Level A harassment takes in addition 
to the unreduced Level B harassment takes as estimated by the various 
take estimation methods in the final rule.
    Response: The Commission has recommended one reasonable approach 
for estimating takes by Level A harassment. Given that there are no 
standard protocols for take estimation, it may reasonably be calculated 
through other means. NMFS has provided justification for the numbers of 
take by Level A harassment authorized for each species in the Estimated 
Take section and refers the reader there.
    In response to the Commission's informal comment regarding the lack 
of certainty of construction plans in Year 5 which was submitted in 
response to the Notice of Receipt of HRCP's application (85 FR 63256; 
October 7, 2020), takes for all species were revised and are shown in 
Table 31. It was assumed that there would be a full year of in-water 
work (312 days). However, the work would consist of removal of 
temporary piles. Level A harassment zones associated with this type of 
activity are small. Therefore, no takes by Level A harassment have been 
authorized for year 5.
    Comment 9: Based on the size of the harassment zones and the fact 
that PSOs cannot keep track of individuals, particularly harbor seals, 
as they move amongst the numerous adjacent sites, the Commission stated 
that an individual could be enumerated as being taken by both Level A 
and Level B harassment in the same day at the same location and/or at 
different sites. The Commission noted that this could be an issue for 
other species as well. As such, the Commission recommended that NMFS 
not reduce the Level B harassment takes by the Level A harassment takes 
and authorize the full number of Level B harassment takes for each 
species.
    Response: NMFS agrees that it is possible that a seal or (other 
marine mammal) could be taken more than once on any given day at the 
same or at a different activity location. However, this is likely true 
for most other incidental take authorizations, especially those where 
the project features more than one active pile installation/removal 
location. It is unclear how the Commission's approach would reduce or 
eliminate the potential for double counting of animals. HRCP and NMFS 
are assuming that a certain number of seals (13.6) could be taken per 
day in the Level B harassment zone. Of this number, some subset may 
enter, and remain inside the Level A harassment zone long enough to 
experience Level A harassment. The Commission referred to previous IHAs 
where NMFS assumed that there would be a given number of Level B 
harassment takes per day that were added to a given number of takes by 
Level A harassment which are not a subset of the Level B harassment 
takes. Either approach is acceptable as long as an accompanying 
explanation is provided. Therefore, NMFS does not agree with the 
Commission's recommendation and does not adopt it.
    Comment 10: The Commission recommended that NMFS require HRCP to 
(1) conduct sound source and sound propagation measurements of (a) 
impact installation of at least three 24-inch and three 54-inch 
concrete piles and three 36-inch piles with and three 36-inch piles 
without a bubble curtain, (b) vibratory installation using multiple 
hammers over multiple days of activities when three or more hammers are 
used in the Core Monitoring Area, (c) jetting of at least 3 42-inch 
piles, and (4) DTH pile installation of six 30-inch, three 36-inch, and 
three 60-inch piles using near-field and far-field hydrophones placed 
mid-water column and (2) include in its hydroacoustic monitoring report 
all of the aforementioned elements. The Commission also recommended 
that NMFS require HRCP to increase the sizes of the shut-down zones and 
Level A harassment zones if the measured data indicate that the zones 
were underestimated.
    Response: NMFS does not concur with these recommendations. NMFS 
agrees that there would be value in conducting sound source 
verification on some of the piles for which DTH installation data is 
not available. However, HRCP has not budgeted for the sound source 
verification and propagation measurements as described by the 
Commission and a requirement of this nature would not be practicable. 
Note that HRCP is conducting a hydroacoustic monitoring study as a 
condition of the US Army Corps of Engineers (USACE) and Virginia Marine 
Resources Commission (VMRC) permits, and it is being designed in 
collaboration with NMFS Greater Atlantic Regional Field Office staff to 
minimize impacts on Atlantic sturgeon. It is likely that some of the 
pile sizes, pile types, and pile installation methods described by the 
Commission will be measured and provide value. The study results and 
preliminary data will be summarized in annual reports, and a final 
report will be made available at the end of the study.
    Comment 11: The Commission recommended that NMFS prohibit HRCP from 
installing or removing new piles after daylight hours in section 217.24 
of the final rule and in any LOA issued under the final rule.
    Response: NMFS does not fully concur with the Commission's 
recommendation. While HRCP has no intention of conducting pile driving 
activities at night, it is unnecessary to preclude such activity should 
the need arise (e.g., on an emergency basis or to complete driving of a 
pile begun during daylight hours, should the construction operator deem 
it necessary to do so). We disagree with the statement that a 
prohibition on pile driving activity outside of daylight hours would 
help to ensure that HRCP is effecting the least practicable adverse 
impact on the affected species, and the Commission does not justify 
this assertion.
    Comment 12: The Commission recommended that NMFS revise section 
217.25(f)(9) in the final rule to require HRCP to report the number of 
individuals of each species detected within the Level A and B 
harassment zones, and estimates of the number of

[[Page 17466]]

marine mammals taken by Level A and B harassment, by species.
    Response: We do not fully concur with the Commission's 
recommendation and do not adopt it as stated. NMFS agrees with the 
recommendation to require HRCP to report the number of individuals of 
each species detected within the Level A and Level B harassment zones 
and NMFS has already included this requirement in the proposed 
regulations, and has included it in the final regulations (Sec.  
217.25(f)(9)) and the final authorization (6(c)(viii)). NMFS does not 
agree with the recommendation to require HRCP to report estimates of 
the numbers of marine mammals taken by Level A and Level B harassment. 
The Commission does not explain why it believes this requirement is 
necessary, nor does it provide recommendations for methods of 
generating such estimates in a manner that would lead to credible 
results. NMFS does not agree that the basic method described in 
footnote 22 of the Commission's 19 November 2020 letter should be 
expected to yield estimates of total take such that readers of HRCP's 
report should have confidence that the estimates are reasonable 
representations of what may have actually occurred.
    Comment 13: The Commission recommended that, for the final rule, 
NMFS include requirements in section 217.25(f) that HRCP include in its 
monitoring report (1) the estimated percentages of the Level A and B 
harassment zones that were not visible and the estimated percentage of 
activities that occurred during nighttime hours, (2) an extrapolation 
of the estimated takes by Level A and B harassment based on the number 
of observed exposures within the Level A and B harassment zones and the 
percentages of the Level A and B harassment zones that were not visible 
or percentage of activities that occurred during nighttime hours (i.e., 
extrapolated takes), and (3) the total number of Level A and B 
harassment takes based on both the observed and extrapolated takes for 
each species.
    Response: We do not fully concur with the Commission's 
recommendation and do not adopt it as stated. NMFS does agree that HRCP 
should report the estimated percentage(s) of the Level A and Level B 
harassment zones that were not visible, and has included this 
requirement in the final regulations (Sec.  217.25(f)(3)) and the final 
authorization (6(c)(iv)). These pieces of information--numbers of 
individuals of each species detected within the harassment zones and 
the estimated percentage(s) of the harassment zones that were not 
visible--may be used to glean an approximate understanding of whether 
HRCP may have exceeded the amount of take authorized. Although the 
Commission does not explain its reasoning for offering these 
recommendations, NMFS' recognizes the basic need to understand whether 
an LOA-holder may have exceeded its authorized take. The need to 
accomplish this basic function of reporting does not require that NMFS 
require applicants to use methods we do not have confidence in to 
generate estimates of ``total take'' that cannot be considered 
reliable.
    Comment 14: The Commission recommended that NMFS reinforce that 
HRCP must keep a running tally of the total Level A and B harassment 
takes, both observed and extrapolated, for each species consistent with 
section 217.24(a)(10) of the final rule.
    Response: The LOA indicates the number of takes authorized for each 
species. We agree that HRCP must ensure they do not exceed authorized 
takes, but do not concur with the Commission's repeated recommendations 
regarding the need for NMFS to oversee incidental take authorization 
(ITA)-holders' compliance with issued ITAs, including the use of a 
``running tally'' of takes. Regardless of the Commission's substitution 
of the word ``reinforce'' for the word ``ensure,'' as compared with its 
prior recommendations for other actions, compliance with the terms of 
an issued LOA remains the responsibility of the LOA-holder.
    Comment 15: A private citizen expressed concern that the planned 
project would require HRCP or NMFS to physically move marine animals 
away from their natural habitat near the project site to some other 
location in the Chesapeake Bay. Another private citizen noted that 
while transportation and relocation of marine mammals may result in 
Level A and Level B harassment of marine mammals, animals would be 
spared exposure to construction activities that could result in extreme 
injury and death.
    Response: There will be no capture and relocation of marine mammals 
away from the project site by NMFS, HRCP, or any other entity. Marine 
mammals are free to move away from or remain in close proximity to the 
project area. Neither NMFS nor HRCP will engage in any activities 
specifically directed to attract or deter marine mammals. Seals that 
move away from the project area will find suitable natural habitat 
across much of the lower Chesapeake Bay. Numerous seal haul-outs are 
located in the lower Bay which are used by seals primarily during the 
winter.

Changes From Proposed to Final Regulations

    NMFS increased take for all species by assuming that pile driving 
activities would take place for a full year (312 work days per year) 
during year 5 instead of a partial year (181 work days per year) as was 
assumed for the proposed rule (86 FR 1588; January 8, 2021) which 
resulted in increased take numbers for all species. Consequently Table 
24, Table 26, Table 29, Table 30 and Table 31 in this notice have been 
revised to reflect this change. The work in Year 5 is anticipated to 
consist of removal of temporary piles, and Level A harassment zones 
associated with this type of activity are small; therefore, no takes by 
Level A harassment are anticipated or have been authorized for Year 5, 
and this is reflected in the revised take estimates in those revised 
tables. Note that table numbers remain unchanged from the proposed rule 
(86 FR 1588; January 8, 2021). Table 3, Table 14, Table 15, Table 32 
and Table 33 have been revised to correct formatting errors found in 
the proposed rule (86 FR 1588; January 8, 2021). In Table 33, shutdown 
zones were rounded up to the nearest 5-m increment instead of the 
nearest 10-m increment for consistency. NMFS has revised Table 11 to 
display the SL sources as well as pile sizes that were used for DTH 
installation. NMFS has included a requirement that HRCP should report 
the estimated percentage(s) of the Level A and Level B harassment zones 
that were not visible. This may be found in the Sec.  217.25(f)(3) of 
the regulations. NMFS received an informal comment from the Commission 
indicating that the HRCP should use 5 PSOs with one stationed at the 
CBBT when multiple hammers are used. NMFS agreed with this 
recommendation. However, after careful consideration it was concluded 
that placing a PSO on the CBBT could present safety hazard. Therefore, 
this measure will not be required.

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/marine-mammal-stock-assessment-reports-region and more general information about 
these species (e.g., physical and

[[Page 17467]]

behavioral descriptions) may be found 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) and draft 2020 SARS available at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessment-reports.

                                          Table 8--Marine Mammal Species Likely To Occur Near the Project Area
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                             Stock abundance  (CV,
                                                                                         ESA/MMPA status;      Nmin, most recent               Annual  M/
             Common name                  Scientific name               Stock            strategic (Y/N) 1    abundance survey) 2      PBR        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           22         58
                                                                                                             SAR).
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                            Superfamily Odontoceti (toothed whales, dolphins, and porpoises):
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Delphinidae:
    Bottlenose dolphin..............  Tursiops truncatus.....  Western North Atlantic   -,-; Y              6,639 (0.41; 4,759;            48  12.2-21.5
                                                                (WNA) Coastal,                               2011).
                                                                Northern Migratory.
                                                               WNA Coastal, Southern    -,-; Y              3,751 (0.06; 2,353;            23       18.3
                                                                Migratory.                                   2011).
                                                               Northern North Carolina  -,-; Y              823 (0.06; 782; 2017).        7.8     7-29.8
                                                                Estuarine System
                                                                (NNCES).
Family Phocoenidae (porpoises):
    Harbor porpoise.................  Phocoena phocoena......  Gulf of Maine/Bay of     -, -; N             95,543 (0.31; 74,034;         851        217
                                                                Fundy.                                       see SAR).
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                         Order Carnivora--Superfamily Pinnipedia
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Phocidae (earless seals):
    Harbor seal.....................  Phoca vitulina.........  WNA....................  -; N                75,834 (0.15; 66,884,       2,006        350
                                                                                                             see SAR).
    Gray seal \4\...................  Halichoerus grypus.....  WNA....................  -; N                27,131 (0.19, 23,158,       1,359      5,410
                                                                                                             see SAR).
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Endangered Species Act (ESA) status: Endangered (E), Threatened (T)/MMPA status: Depleted (D). A dash (-) indicates that the species is not listed
  under the ESA or designated as depleted under the MMPA. Under the MMPA, a strategic stock is one for which the level of direct human-caused mortality
  exceeds PBR or which is determined to be declining and likely to be listed under the ESA within the foreseeable future. Any species or stock listed
  under the ESA is automatically designated under the MMPA as depleted and as a strategic stock.
\2\ NMFS marine mammal stock assessment reports online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessment-reports-region. CV is coefficient of variation; Nmin is the minimum estimate of stock abundance. In some cases, CV is not applicable.
\3\ These values, found in NMFS's SARs, represent annual levels of human-caused mortality plus serious injury from all sources combined (e.g.,
  commercial fisheries, ship strike). Annual M/SI often cannot be determined precisely and is in some cases presented as a minimum value or range. A CV
  associated with estimated mortality due to commercial fisheries is presented in some cases.
\4\ The 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 are authorizing 
take.
    A detailed description of the species likely to be affected by 
HRCP's project, including brief introductions to the species and 
relevant stocks as well as available information regarding population 
trends and threats, and information regarding local occurrence, were 
provided in the proposed rule (86 FR 1588; January 8, 2021); since that 
time, other than minor stock assessment changes, we are not aware of 
any changes in the status of these species and stocks; therefore, 
detailed descriptions are not provided here. Please refer to the 
proposed rule for these descriptions (86 FR 1588; January 8, 2021). 
Please also refer to NMFS' website (https://www.fisheries.noaa.gov/find-species) for generalized species accounts.

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

[[Page 17468]]

been successfully completed for mysticetes (i.e., low-frequency 
cetaceans). Subsequently, NMFS (2018) described generalized hearing 
ranges for these marine mammal hearing groups. Generalized hearing 
ranges were chosen based on the approximately 65 decibel (dB) threshold 
from the normalized composite audiograms, with the exception for lower 
limits for low-frequency cetaceans where the lower bound was deemed to 
be biologically implausible and the lower bound from Southall et al. 
(2007) retained. Marine mammal hearing groups and their associated 
hearing ranges are provided in Table 9.

           Table 9--Marine Mammal Hearing Groups (NMFS, 2018)
------------------------------------------------------------------------
            Hearing group                 Generalized hearing range *
------------------------------------------------------------------------
Low-frequency (LF) cetaceans (baleen  7 Hz to 35 kHz.
 whales).
Mid-frequency (MF) cetaceans          150 Hz to 160 kHz.
 (dolphins, toothed whales, beaked
 whales, bottlenose whales).
High-frequency (HF) cetaceans (true   275 Hz to 160 kHz.
 porpoises, Kogia, river dolphins,
 cephalorhynchid, Lagenorhynchus
 cruciger & L. australis).
Phocid pinnipeds (PW) (underwater)    50 Hz to 86 kHz.
 (true seals).
Otariid pinnipeds (OW) (underwater)   60 Hz to 39 kHz.
 (sea lions and fur seals).
------------------------------------------------------------------------
* Represents the generalized hearing range for the entire group as a
  composite (i.e., all species within the group), where individual
  species' hearing ranges are typically not as broad. Generalized
  hearing range chosen based on ~65 dB threshold from normalized
  composite audiogram, with the exception for lower limits for LF
  cetaceans (Southall et al. 2007) and PW pinniped (approximation).

    The pinniped functional hearing group was modified from Southall et 
al. (2007) on the basis of data indicating that phocid species have 
consistently demonstrated an extended frequency range of hearing 
compared to otariids, especially in the higher frequency range 
(Hemil[auml] et al., 2006; Kastelein et al., 2009; Reichmuth and Holt, 
2013).
    For more detail concerning these groups and associated frequency 
ranges, please see NMFS (2018) for a review of available information. 
Five marine mammal species (three cetacean and two phocid pinniped 
species) have the reasonable potential to co-occur with the planned 
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

    The effects of underwater noise from HRCP's activities have the 
potential to result in harassment of marine mammals in the vicinity of 
the survey area. The proposed rule (86 FR 1588; January 8, 2021) 
included a discussion of the effects of anthropogenic noise on marine 
mammals and the potential effects of underwater noise from HRCP's 
construction activities on marine mammals and their habitat. That 
information and analysis is incorporated by reference into this final 
rule and is not repeated here; please refer to the proposed rule (86 FR 
1588; January 8, 2021).
    The Estimated Take section 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 Mitigation Measures 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. We also provided 
additional description of sound sources in our proposed rule (86 FR 
1588; January 8, 2021).

Estimated Take

    This section provides an estimate of the number of incidental takes 
authorized by NMFS through the 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 high-frequency 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 required 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 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 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

[[Page 17469]]

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 [mu]Pa (rms) for continuous (e.g., vibratory pile-driving, 
drilling) and above 160 dB re 1 [mu]Pa (rms) for non-explosive 
impulsive (e.g., seismic airguns) or intermittent (e.g., scientific 
sonar) sources.
    HRCP's planned 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 [mu]Pa (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 non-impulsive). As noted previously, HRCP's planned 
activity includes the use of impulsive (impact pile driving, DTH pile 
installation) and non-impulsive (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-technical-guidance.

                     Table 10--Thresholds Identifying the Onset of Permanent Threshold Shift
----------------------------------------------------------------------------------------------------------------
                                                    PTS onset acoustic thresholds *  (received level)
             Hearing group              ------------------------------------------------------------------------
                                                  Impulsive                         Non-impulsive
----------------------------------------------------------------------------------------------------------------
Low-Frequency (LF) Cetaceans...........  Cell 1: Lpk,flat: 219 dB;   Cell 2: LE,LF,24h: 199 dB.
                                          LE,LF,24h: 183 dB.
Mid-Frequency (MF) Cetaceans...........  Cell 3: Lpk,flat: 230 dB;   Cell 4: LE,MF,24h: 198 dB.
                                          LE,MF,24h: 185 dB.
High-Frequency (HF) Cetaceans..........  Cell 5: Lpk,flat: 202 dB;   Cell 6: LE,HF,24h: 173 dB.
                                          LE,HF,24h: 155 dB.
Phocid Pinnipeds (PW) (Underwater).....  Cell 7: Lpk,flat: 218 dB;   Cell 8: LE,PW,24h: 201 dB.
                                          LE,PW,24h: 185 dB.
Otariid Pinnipeds (OW) (Underwater)....  Cell 9: Lpk,flat: 232 dB;   Cell 10: LE,OW,24h: 219 dB.
                                          LE,OW,24h: 203 dB.
----------------------------------------------------------------------------------------------------------------
* Dual metric acoustic thresholds for impulsive sounds: Use whichever results in the largest isopleth for
  calculating PTS onset. If a non-impulsive sound has the potential of exceeding the peak sound pressure level
  thresholds associated with impulsive sounds, these thresholds should also be considered.
Note: Peak sound pressure (Lpk) has a reference value of 1 [mu]Pa, and cumulative sound exposure level (LE) has
  a reference value of 1[mu]Pa\2\s. In this Table, thresholds are abbreviated to reflect American National
  Standards Institute standards (ANSI 2013). However, peak sound pressure is defined by ANSI as incorporating
  frequency weighting, which is not the intent for this Technical Guidance. Hence, the subscript ``flat'' is
  being included to indicate peak sound pressure should be flat weighted or unweighted within the generalized
  hearing range. The subscript associated with cumulative sound exposure level thresholds indicates the
  designated marine mammal auditory weighting function (LF, MF, and HF cetaceans, and PW and OW pinnipeds) and
  that the recommended accumulation period is 24 hours. The cumulative sound exposure level thresholds could be
  exceeded in a multitude of ways (i.e., varying exposure levels and durations, duty cycle). When possible, it
  is valuable for action proponents to indicate the conditions under which these acoustic thresholds will be
  exceeded.

Ensonified Area

    Here, we describe operational and environmental parameters of the 
activity that will feed into identifying the area ensonified above the 
acoustic thresholds, which include source levels and transmission loss 
coefficient.
    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

[[Page 17470]]

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)
----------------------------------------------------------------------------------------------------------------
                                             Sound source level at 10 meters
           Method and pile type            -----------------------------------         Literature source
                                                         dB  rms
----------------------------------------------------------------------------------------------------------------
Vibratory Hammer:
    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:
    42-inch steel pile....................                               161   Austin et al. 2016
----------------------------------------------------------------------------------------------------------------


 
                                             Sound source level at 10 meters
           Method and pile type           ------------------------------------         Literature source
                                             dB  rms     dB  SEL    dB  peak
----------------------------------------------------------------------------------------------------------------
DTH Pile Installation:
    30-inch and 36-inch steel pipe piles.      1 166       2 164       3 196   Denes et al. 2016, 2019; Reyff
                                                                                and Heyvaert 2019; Reyff 2020.
    60-inch steel pipe pile..............      1 166         175         196   Denes et al. 2016; Reyff pers.
                                                                                comm.
Impact Hammer:
    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,         188         179         209   DoN 2015.
     attenuated **.
    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.
1 SSL for Level B harassment based on DTH-installation of 24-inch steel pile (Denes et al. 2016).
2 SSL for Level A harassment based on DTH-installation of 42-inch steel piles (Reyff and Heyvaert 2019).
3 SSL for Level A harassment based on DTH-installation of 42-inch steel piles (Reyff 2020).

    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

[[Page 17471]]

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
----------------------------------------------------------------------------------------------------------------
                                                                       Level A harassment    Level B harassment
           Hammer types                     Difference in SSL                 zones                 zones
----------------------------------------------------------------------------------------------------------------
Vibratory, Impact.................  Any.............................  Use impact zones....  Use vibratory zone.
Impact, Impact....................  Any.............................  Use zones for each    Use zone for each
                                                                       pile size and         pile size.
                                                                       number of strikes.
Vibratory, Vibratory..............  0 or 1 dB.......................  Add 3 dB to the       Add 3 dB to the
                                                                       higher source level.  higher source
                                                                                             level.
                                    2 or 3 dB.......................  Add 2 dB to the       Add 2 dB to the
                                                                       higher source level.  higher source
                                                                                             level.
                                    4 to 9 dB.......................  Add 1 dB to the       Add 1 dB to the
                                                                       higher source level.  higher source
                                                                                             level.
                                    10 dB or more...................  Add 0 dB to the       Add 0 dB to the
                                                                       higher source level.  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 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.

                                                     Table 13--Possible Vibratory Pile Combinations
--------------------------------------------------------------------------------------------------------------------------------------------------------
                        Method                                      24     24+24    30/36      42     30/36+24   24+42   30/36+30/36   42+30/36   42+42
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                          SSL
                Pile diameter  (inches)                   (dB)     161      164      167      168       168       169        170         171       171
--------------------------------------------------------------------------------------------------------------------------------------------------------
Vibratory:
    24................................................      161      164      166      168      169        169      169          171        171      172
    DTH...............................................      166      167      168      170      170        170      171          172        172      172
    30/36.............................................      167      168      169      170      171        171      171          172        172      172
    42................................................      168      169      169      171      171        171      172          172        172      173
--------------------------------------------------------------------------------------------------------------------------------------------------------

    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 authorized for take 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

[[Page 17472]]

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.

                                Table 14--User Spreadsheet Input Parameters Used for Calculating Level A Harassment Isopleths for Vibratory and Impact Hammers *
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
            Model parameter               Steel  16-inch       24-inch steel        24-inch  30-inch steel, concrete                   36-inch steel                    42-inch steel    54-inch
----------------------------------------  sheet   timber ------------------------- concrete           filled         ------------------------------------------------------------------ concrete
                                        -----------------                         -----------------------------------                                                                  ---------
                                                            Vib     Imp     Imp-                               Imp-     Vib     Vib     Vib     Vib     Imp     Imp-     Vib   Jetting
                                           Vib     Vib                     bubble     Imp      Vib     Imp    bubble                                           bubble                      Imp
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Spreadsheet Tab........................     A.1      A.1     A.1     E.1      E.1       E.1     A.1     E.1      E.1     A.1     A.1     A.1     A.1     E.1      E.1     A.1      A.1       E.1
Weighting Factor Adjustment (kHz)......     2.5      2.5     2.5       2        2         2     2.5       2        2     2.5     2.5     2.5     2.5       2        2     2.5      2.5         2
Sound Pressure Level (SPLrms)..........     160      162     161     190      183       176     167     195      188     167     167     167     167     193      186     168      161       187
SELss (LE, p, single strike) at 10       ......  .......  ......     177      170       166  ......     186      179  ......  ......  ......  ......     183      176  ......  .......       177
 meters................................
Lp, 0-pk at 10 meters..................  ......  .......  ......     203      196       188  ......     216      209  ......  ......  ......  ......     210      203  ......  .......       193
Number of piles within 24-hour period..      10        4       6       6        6         1       6       6        6       1  8 & 16   2 & 3       2   2 & 3        2       6        1         1
Estimated Duration to drive a single         30       30   30/60  ......  .......  ........      60  ......  .......      50       5      50      60  ......  .......      30       30  ........
 pile (min)............................
50% of Duration to drive a single pile       15       15   15/30  ......  .......  ........      30  ......  .......      25     2.5      25      30  ......  .......      15       15  ........
 (min).................................
Transmission loss coefficient..........      15       15      15      15       15        15      15      15       15      15      15      15      15      15       15      15       15        15
Distance from sound pressure level           10       10      10      10       10        10      10      10       10      10      10      10      10      10       10      10       10        10
 (SPLrms) measurement (m)..............
Estimated Strikes per pile.............  ......  .......  ......      40       40     2,100  ......      40       40  ......  ......  ......  ......      40       40  ......  .......     2,100
50% of Strikes per pile................  ......  .......  ......      20       20     1,050  ......      20       20  ......  ......  ......  ......      20       20  ......  .......     1,050
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
* 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. HRCP has implemented this reduction across all pile sizes, types, and installation and removal methods. For purposes of vibratory installation, the duration of
  installation was reduced by half to accomplish the reduction. For impact installation, the number of strikes per pile was reduced by half to accomplish the reduction.


 Table 15--User Spreadsheet Input Parameters Used for Calculating Level A Harassment Isopleths for Drilling With
                                                 a DTH Hammer *
----------------------------------------------------------------------------------------------------------------
                                                                  30-inch steel,   36-inch steel   60-inch steel
                                                                     concrete
                         Model parameter                              filled     -------------------------------
                                                                 ----------------
                                                                        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
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                             Level A harassment isopleth distance      Level A harassment isopleth areas  (km2)
                                                                                     Minutes                               (meters)
                                                                                     per pile  Number of ---------------------------------------------------------------------------------------
               Project component                           Pile size/type            (reduced  piles per             Cetaceans             Pinnipeds             Cetaceans             Pinnipeds
                                                                                     by half)     day    ---------------------------------------------------------------------------------------
                                                                                                              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  .........

[[Page 17473]]

 
    North Shore Work Trestle, Jump Trestle,      36-inch Pipe, Steel..............         25          2         16          2         23         10  .........  .........      <0.01  .........
     Work Trestle, Demolition Trestle.
    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             30          6         36          4         53         22  .........  .........  .........  .........
                                                  Filled.
    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       36-inch Pipe, Steel..............         25          2         16          2         23         10  .........  .........  .........  .........
     Trestle, Temporary MOT Trestle.
    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  .........
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------


[[Page 17474]]


                                                  Table 17--Calculated Distances to Level A Harassment Isopleths During Impact Installation and
                                                                            DTH Pile Installation With No Attenuation
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                    Number of                Level A harassment isopleth distance     Level A harassment isopleth areas  (km\2\)
                                                                                     strikes                               (meters)                  -------------------------------------------
                                                                                     per pile  Number of --------------------------------------------       Cetaceans             Pinnipeds
               Project component                           Pile size/type           or strike  piles per        Cetaceans             Pinnipeds      -------------------------------------------
                                                                                      rate *      day    --------------------------------------------
                                                                                     (reduced                                                             LF         MF         HF         PW
                                                                                     by half)                 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             20          6        386         14        459        207       0.35     <0.001       0.49       0.10
                                                  Filled.
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                          South Trestle
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Work Trestle, Jump Trestle, Demolition Trestle,  36-inch Pipe, Steel..............         20          2        117          5        140         63       0.04     <0.001       0.06       0.01
 Temporary MOT Trestle.
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         36,000          6      1,946         70      2,318      1,042       8.28      <0.01      11.30       2.49
                                                  Filled.
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                          South Trestle
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Work Trestle, Jump Trestle, Temporary MOT        36-inch Pipe, Steel..............     36,000          2        936         34      1,115        501       2.67      <0.01       3.67       0.79
 Trestle, Demolition Trestle.
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.


[[Page 17475]]


                                                    Table 18--Calculated Distances to Level A Harassment Isopleths During Impact Installation
                                                                                        With Attenuation
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                             Level A harassment isopleth distance     Level A harassment isopleth areas  (km\2\)
                                                                                    Number of                              (meters)                  -------------------------------------------
                                                                                     strikes   Number of --------------------------------------------       Cetaceans             Pinnipeds
               Project component                           Pile size/type            per pile  piles per        Cetaceans             Pinnipeds      -------------------------------------------
                                                                                     (reduced     day    --------------------------------------------
                                                                                     by half)                 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             20          6        132          5        157         71       0.04     <0.001       0.06       0.01
                                                  Filled.
South Trestle:
                                                                                                                                                     ----------------------
    Temporary MOT Trestle......................  36-inch Pipe, Steel..............         20          2         40          2         48         22         <0.001             0.007      0.002
    Jump Trestle
    Work Trestle
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

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 appropriate 
assumption for HRCP's planned 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
----------------------------------------------------------------------------------------------------------------
                                                                                      Level B      Level B area
            Location and component                    Method and pile type         isopleth (m),   unattenuated
                                                                                   unattenuated       (km\2\)
----------------------------------------------------------------------------------------------------------------
                                  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.....................  AZ 700-19 steel sheet piles.....           4,642           36.73
    South.....................................
South Island:
    Moorings..................................  42-inch steel piles.............          15,849          246.86
    Template Piles............................  36-inch steel piles.............          13,594           81.75

[[Page 17476]]

 
    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             13,594          194.04
                                                 filled.
    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
    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,   36-inch steel piles.............          11,659           72.28
     Demolition Piles, Templates.
    South Island Deep Foundation Piles........  30-inch steel piles, concrete             11,659          152.79
                                                 filled.
    South Trestle Casings.....................  60-inch steel piles.............          11,659          184.12
    South Trestle Work Trestle, Jump Trestle,   36-inch steel piles.............          11,659           14.12
     Demolition Trestle, Temporary MOT
     Trestle, Templates.
    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              2,154            9.91
                                                 filled.
    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
----------------------------------------------------------------------------------------------------------------


[[Page 17477]]


    Table 20--Distances to Level B Harassment Isopleths for Installation and Removal of Steel Pipe Piles With
                                           Attenuation Bubble Curtain
----------------------------------------------------------------------------------------------------------------
                                                                                      Level B      Level B area
            Location and component                    Method and pile type         isopleth (m),    attenuated
                                                                                    attenuated        (km\2\)
----------------------------------------------------------------------------------------------------------------
                                    Impact Hammer (Level B Isopleth = 160 dB)
----------------------------------------------------------------------------------------------------------------
South Island:
    Deep Foundation Piles.....................  30-inch steel piles, concrete                736            1.25
                                                 filled.
Settlement Reduction Piles                      24-inch steel piles.............             341            0.27
South Trestle:
    Temporary MOT Trestle, Work Trestle, Jump   36-inch steel piles.............             541            0.68
     Trestle.
----------------------------------------------------------------------------------------------------------------

    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
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                Level A harassment isopleth distance  (meters)
                                                                                     -------------------------------------------------------------------
                Pile size/type                   Minutes per pile   Number of piles                       Cetaceans                         Pinnipeds
                                                (reduced by half)       per day      -------------------------------------------------------------------
                                                                                             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
------------------------------------------------------------------------
                                                     Distance to Level B
                Combined SSL  (dB)                   isopleth  (meters)
------------------------------------------------------------------------
164...............................................                 8,577
165...............................................                10,000
166...............................................                11,659
167...............................................                13,594
168...............................................                15,849
169...............................................                18,478
170...............................................                21,544
171...............................................                25,119
172...............................................                29,286
173...............................................                34,145
------------------------------------------------------------------------


[[Page 17478]]

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 duration of in-water 
pile installation and removal. NMFS concurs with the request and is 
authorizing a total of 183 takes of humpback whales over the 5-year 
Project period (Table 24). This number is increased from 172 included 
in the proposed rule due to the increased number of assumed pile 
driving days in Year 5. Only vibratory extraction is planned for Year 5 
which will result in smaller PTS zones. Therefore take by Level A 
harassment is not expected. 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 and 
remain for a sufficient duration to incur PTS. Therefore, HRCP 
requested and NMFS is authorizing eight humpback whale takes by Level A 
harassment (2 per year except for Year 5 when there are no requests) 
and 35 Level B harassment takes each year (Table 24).

                               Table 23--Summary of Individual Humpback Whale Sightings by Month From 2012 to 2019 in the
                                                                     Chesapeake Bay
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                        Engelhaupt surveys                           Aschettino surveys
                             Month                             -----------------------------------------------------------------------------------------
                                                                  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.


   Table 24--Summary of the Estimated Numbers of Humpback Whales Potentially Exposed to Level A and Level B Harassment Sound Levels per Month per Year
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                                                  Annual
             Year                Mar     Apr     May     Jun     Jul     Aug    Sept     Oct     Nov     Dec     Jan     Feb   Level A  Level B   total
--------------------------------------------------------------------------------------------------------------------------------------------------------
Year 1.......................       4       3       2       2       2       2       2       2       4       4       4       4        2       35       37
Year 2.......................       4       3       2       2       2       2       2       2       4       4       4       4        2       35       37
Year 3.......................       4       3       2       2       2       2       2       2       4       4       4       4        2       35       37
Year 4.......................       4       3       2       2       2       2       2       2       4       4       4       4        2       35       37
Year 5.......................       4       3       2       2       2       2       2       2       4       4       5       5        0       35       35
                              --------------------------------------------------------------------------------------------------------------------------
    Monthly 5-Year Total.....      20      15      10      10      10      10      10      10      20      20      21      21        8      175      183
--------------------------------------------------------------------------------------------------------------------------------------------------------

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

[[Page 17479]]

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 Bridge-
Tunnel (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 5 years. Due to the complex schedule and the inexact timeline in 
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 km\2\) 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
----------------------------------------------------------------------------------------------------------------
                                                                            Average number of   Seasonal density
                                                             Number of      dolphins  sighted     outside core
                         Season                            sightings per      per day within    monitoring area
                                                               season        core  monitoring    (individuals/
                                                                                   area              km\2\)
----------------------------------------------------------------------------------------------------------------
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 km\2\ Level B 
harassment zone each and 2 piles with a 50 km\2\ Level B harassment 
zone, the formula would be:

((5 piles * 20 km\2\/pile) + (2 piles * 50 km\2\/pile))/(7 piles) = 
weighted average of 28.6 km\2\.

    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.

[[Page 17480]]



Table 26--Monthly and Annual Estimated Dolphin Exposures Using Number/Day for Core Monitoring Area, and Density/km2 for Areas Extending Outside the Core
                                                           Monitoring Area into Chesapeake Bay
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                                                  Annual
                                       Mar      Apr      May      Jun      Jul      Aug      Sept     Oct      Nov      Dec      Jan      Feb     total
--------------------------------------------------------------------------------------------------------------------------------------------------------
Dolphin density (#/km\2\)..........        1        1        1     3.55     3.55     3.55     3.88     3.88     3.88     0.63     0.63     0.63  .......
Year 1 In CMA......................      468      451      451      427      444      427      708      708      681        0        0        0    4,765
Year 1 Out CMA.....................      539      539      539    1,914    1,022    1,022    2,989    2,980    2,963      476      428      953   16,362
Year 2 In CMA......................      468      451      451      427      444      427      708      708      681        0        0        0    4,763
Year 2 Out CMA.....................    2,297    1,304      706    2,631    2,464    1,627    1,342    6,770    6,758    1,097    1,526    1,498   30,021
Year 3 In CMA......................      468      451      451      427      444      427      708      708      681        0        0        0    4,764
Year 3 Out CMA.....................    2,440    1,622    1,622        0        0    5,122        0        0   14,058    2,070    2,090    1,537   30,562
Year 4 In CMA......................      468      451      451      427      444      427      708      708      681        0        0        0    4,764
Year 4 Out CMA.....................        0        0        0        0        0        0   10,146    9,287    6,009      444        0        0   25,884
Year 5 In CMA......................      468      451      451      427      444      427      708      708      681        0        0        0    4,763
Year 5 Out CMA.....................      360        0        0        0        0        0        0        0        0        0      267      227      854
--------------------------------------------------------------------------------------------------------------------------------------------------------

    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 km\2\. 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 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 authorizing 127,502 exposures by Level B harassment and 1,222 
exposures by Level A harassment of bottlenose dolphins divided among 
the 5 project construction years (127,502 total exposures -1,222 Level 
A harassment takes = 126,280 Level B harassment takes). However, due to 
the construction schedule, these takes will not occur equally during 
each year of the LOA. There are no Level A harassment takes authorized 
for year 5. The maximum annual harassment number for dolphins is 35,326 
in Year 3.
    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 x 3 months per year = 6 harbor 
porpoises) per year.
    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 km\2\ (Table 17). However, HRCP has planned a 100-meter 
shutdown zone for harbor porpoises. HRCP has requested small numbers of 
take by Level A harassment for harbor porpoises during Years 1-4 of 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 authorizing 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 authorizing 6 takes by 
Level B harassment and no takes 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

[[Page 17481]]

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
----------------------------------------------------------------------------------------------------------------
                                                                                                        Monthly
                     Month                         2014     2015     2016     2017     2018     2019    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
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
----------------------------------------------------------------------------------------------------------------
                                                     Number of      Total seal     Average daily     Max daily
                  Field season                      survey days        count        seal count      seal count
----------------------------------------------------------------------------------------------------------------
2014-2015.......................................              11             113              10              33
2015-2016.......................................              14             187              13              39
2016-2017.......................................              22             308              14              40
2017-2018.......................................              15             340              23              45
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
----------------------------------------------------------------------------------------------------------------
                                                                                                          Annual
             Year                Nov     Dec     Jan     Feb     Mar     Apr     May   Level A  Level B   total
----------------------------------------------------------------------------------------------------------------
Year 1.......................     177     367     354     326     367     354     177      424    1,697    2,122
Year 2.......................     177     367     354     326     367     354     177      424    1,697    2,122
Year 3.......................     177     367     354     326     367     354     177      424    1,697    2,122
Year 4.......................     177     367     354     326     367     354     177      424    1,697    2,122
Year 5.......................     177     367     354     326     367     354     177        0    2,122    2,122
                              ----------------------------------------------------------------------------------
    Monthly 5-Year Total.....     884   1,836   1,768   1,632   1,836   1,768     884    1,696    8,910   10,608
----------------------------------------------------------------------------------------------------------------
\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.
    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 km\2\. 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 is authorizing 1,697 takes by Level B harassment 
and 424 takes by Level A harassment for project years 1-4 and 2,122 
Level B harassment takes and no Level A harassment takes of harbor 
seals for project year 5 since only vibratory extraction will be 
occurring in the last year. (Table 29).

[[Page 17482]]

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 
authorizing nine gray seal takes per year for 5 years (3 gray seals per 
month x 3 months per year = 9 gray seals) for a total of 45 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, eight takes by Level A harassment 
have also been requested (2 during years 1-4 and 0 during year 5). NMFS 
concurs with this assessment and is authorizing seven takes by Level B 
harassment and two takes by Level A harassment per year for years 1-4 
(9 takes-2 takes by Level A harassment = 7 takes by Level B harassment) 
and 9 takes by Level B harassment, with no authorized takes by Level A 
harassment, in year 5.
    Table 30 below summarizes authorized 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.

                                         Table 30--Estimated Take by Level A and Level B Harassment, by Species
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                    2021                  2022                  2023                  2024                  2025
                  Species                  -------------------------------------------------------------------------------------------------------------
                                             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         37
Bottlenose dolphin........................        212     20,915        349     34,435        354     34,972        307     30,341          0      5,617
Harbor porpoise...........................          2          4          2          4          2          4          2          4          0          6
Harbor seal...............................        424      1,697        424      1,697        424      1,697        424      1,697          0      2,121
Gray seal.................................          2          7          2          7          2          7          2          7          0          9
--------------------------------------------------------------------------------------------------------------------------------------------------------


Table 31--Maximum Annual Estimated Take by Level A and Level B Harassment, by Species and Stock in Comparison to
                                                 Stock Abundance
----------------------------------------------------------------------------------------------------------------
                                                                                    Level A and
                                                                       Stock          Level B       Percent  of
                Species                           Stock              abundance      harassment         stock
                                                                                       takes
----------------------------------------------------------------------------------------------------------------
Humpback Whale........................  Gulf of Maine...........      \b\ 12,312              37             0.3
Bottlenose Dolphin....................  WNA Coastal, Northern              6,639          17,561           264.5
                                         Migratory \a\.
                                        WNA Coastal, Southern              3,751          17,561           468.2
                                         Migratory \a\.
                                        NNCES \c\...............             823             200            24.3
Harbor Porpoise.......................  Gulf of Maine/Bay of              95,543               6           <0.01
                                         Fundy.
Harbor Seal...........................  Western North Atlantic..          75,834           2,121             2.8
Gray Seal.............................  Western North Atlantic..         505,000               9           <0.01
----------------------------------------------------------------------------------------------------------------
\a\ Take estimates are weighted based on calculated percentages of population for each distinct stock, assuming
  animals present would follow same probability of presence in the project area. Please see the Small Numbers
  section for additional information.
\b\ West Indies DPS from Bettridge et al. 2015.
\c\ Assumes multiple repeated takes of same individuals from small portion of each stock as well as repeated
  takes of Chesapeake Bay resident population (size unknown). Please see the Small Numbers section for
  additional information.

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.

[[Page 17483]]

    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.
    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; and
     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; and
     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
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                             Number of            Level A harassment isopleth distance  (meters)
                                                       Minutes (min) per       piles     ---------------------------------------------------------------
             Method               Pile size and type    pile or strikes    installed or                      Cetaceans
                                                           per pile         removed per  ------------------------------------------------    Pinnipeds
                                                                                day             LF              MF              HF
--------------------------------------------------------------------------------------------------------------------------------------------------------
Vibratory Installation and        24-inch Pipe,       15 min............               6       \1\ 10/55              10       \2\ 14/85       \3\ 15/35
 Removal.                          Steel.
                                  30-inch Pipe,       30 min............               6           15/55  ..............           21/85  ..............
                                   Steel, Concrete                                                 36/55                           60/85
                                   Filled.
                                  36-inch Pipe,       2.5 min...........               8           10/55  ..............           13/85  ..............
                                   Steel.
                                                      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,       15 min............               6           27/55  ..............           39/85  ..............
                                   Steel.
                                  Sheet, Steel......  15 min............              10           11/55  ..............           16/85  ..............
                                  16-inch CCA,        15 min............               4           10/55  ..............           12/85  ..............
                                   Timber.
Jetting.........................  42-inch Pipe,       15 min............               1              10  ..............              10  ..............
                                   Steel.
Down-the-Hole Installation......  30-inch Pipe,       36,000 strikes *..               6           1,950              70             100  ..............
                                   Steel, Concrete
                                   Filled.
                                  36-inch Pipe,                                        2             940              34  ..............  ..............
                                   Steel.
                                  60-inch Pipe,                                        3           6,640             240  ..............  ..............
                                   Steel.
Impact Installation.............  24-inch Pipe,       20 strikes........               6             100              10  ..............  ..............
                                   Steel.

[[Page 17484]]

 
                                  30-inch Pipe,                                                      390              14  ..............  ..............
                                   Steel, Concrete
                                   Filled.
                                  36-inch Pipe,                                        2             120              10  ..............  ..............
                                   Steel.
                                  36-inch Pipe,                                        3             160              10  ..............  ..............
                                   Steel.
                                  24-inch Pipe,       1,050 strikes.....               1              80              10  ..............  ..............
                                   Concrete Square.
                                  54-inch Pipe,                                                      420              15  ..............  ..............
                                   Concrete Cylinder.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ A 55-meter shutdown zone will be implemented for humpback whales during concurrent vibratory driving of two or more hammers.
\2\ A 85-meter shutdown zone will be implemented for harbor porpoise during concurrent vibratory driving of two or more hammers.
\3\ A 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
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                  Level A harassment isopleth distance  (meters)
                                                                                         ---------------------------------------------------------------
             Method               Pile size and type   Strikes  per pile     Number of                       Cetaceans                       Pinnipeds
                                                                           piles per day ---------------------------------------------------------------
                                                                                                LF              MF              HF              PW
--------------------------------------------------------------------------------------------------------------------------------------------------------
Impact Installation.............  24-inch Pipe,       20 strikes........               6              35              10              40              20
                                   Steel.
                                  30-inch Pipe,                                                      135              10             160              75
                                   Steel, Concrete
                                   Filled.
                                  36-inch Pipe,       20 strikes........               2              40              10              50              25
                                   Steel.
--------------------------------------------------------------------------------------------------------------------------------------------------------

Protected Species Observers

    The placement of PSOs during all pile driving and removal 
activities (described in the 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.

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; and
     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

[[Page 17485]]

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 planned measures, as well as 
other measures considered by NMFS, NMFS has determined that the planned 
mitigation measures provide the means of effecting the least 
practicable impact on the affected species or stocks and their habitat, 
paying particular attention to rookeries, mating grounds, and areas of 
similar significance.

Monitoring and Reporting

    In order to issue an 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);
     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); and
     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

[[Page 17486]]

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 five 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); and percentages of Level A and 
Level B harassment zones that are not visible;
     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 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; and
     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., population-
level effects). An estimate of the number of takes alone is not enough 
information on which to base an impact determination. In addition to 
considering estimates of the number of marine mammals that might be 
``taken'' through harassment, NMFS considers other factors, such as the 
likely nature of any responses (e.g., intensity,

[[Page 17487]]

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 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 planned 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 authorized takes to exacerbate or 
compound upon these ongoing UMEs. As noted previously, no injury, 
serious injury, or mortality is expect or authorized, 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 required 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 authorized 
for this stock annually, we do not expect this 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 authorizing no more 
than 37 takes by Level A and 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, authorized Level A and 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

[[Page 17488]]

(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 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 planned monitoring and 
mitigation measures, NMFS finds that the total marine mammal take from 
the planned 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 
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 July-August, the stock is 
presumed to occupy coastal waters north of Cape Lookout, North 
Carolina, to Assateague, Virginia, including the Chesapeake Bay. There 
is likely some overlap between the northern and southern migratory 
stocks during spring and fall migrations, but the extent of overlap is 
unknown.
    The Chesapeake Bay and waters offshore of 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 (July-August). 
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 km\2\, while the NNCES stock occupies over 8,000 km\2\ 
(LeBrecque et al., 2015). Given this large range, it is again unlikely 
that a preponderance of animals from the NNCES stock would depart the 
North Carolina estuarine system and travel to the northern extent of 
the stock's range. However, recent evidence suggests that there is 
likely a small resident community of NNCES dolphins of indeterminate 
size that inhabits the Chesapeake Bay year-round (E. Patterson, NMFS, 
pers. comm.).
    Many of the dolphin observations in the Bay are likely repeated 
sightings of the same individuals. The Potomac-Chesapeake Dolphin 
Project has observed over 1,200 unique animals since observations began 
in 2015. Re-sightings of the same individual can be

[[Page 17489]]

highly variable. Some dolphins are observed once per year, while others 
are highly regular with greater than 10 sightings per year (J. Mann, 
Potomac-Chesapeake Dolphin Project, pers. comm.). Similarly, using 
available photo-identification data, Engelhaupt et al. (2016) 
determined that specific individuals were often observed in close 
proximity to their original sighting locations and were observed 
multiple times in the same season or same year. Ninety-one percent of 
re-sighted individuals (100 of 110) in the study area were recorded 
less than 30 km from the initial sighting location. Multiple sightings 
of the same individual would considerably reduce the number of 
individual animals that are taken by Level B harassment. Furthermore, 
the existence of a resident dolphin population in the Bay would 
increase the percentage of dolphin takes that are actually re-sightings 
of the same individuals in 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 planned activity 
(including the planned mitigation and monitoring measures) and the 
anticipated take of marine mammals, NMFS finds that small numbers of 
marine mammals will be taken relative to the population size of the 
affected species or stocks.

Unmitigable Adverse Impact Analysis and Determination

    There are no relevant subsistence uses of the affected marine 
mammal stocks or species implicated by this action. Therefore, NMFS has 
determined that the total taking of affected species or stocks would 
not have an unmitigable adverse impact on the availability of such 
species or stocks for taking for subsistence purposes.

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 final 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.

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 determined that the 
issuance of regulations and the LAO qualifies to be categorically 
excluded from further NEPA review.

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 
propose to authorize take for endangered or threatened species.
    No incidental take of ESA-listed species is planned 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.

Classification

    Pursuant to the procedures established to implement Executive Order 
12866, the Office of Management and Budget has determined that this 
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 
certified to the Chief Counsel for Advocacy of the Small Business 
Administration at the proposed rule stage that this action will 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 final regulations, and HRCP is not a small 
governmental jurisdiction, small organization, or small business, as 
defined by the RFA. No comments were received regarding this 
certification or on the economic impacts of the rule more generally. As 
a result, 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 final rule contains 
collection-of-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.

Waiver of Delay in Effective Date

    The Assistant Administrator for Fisheries has determined that there 
is

[[Page 17490]]

good cause under the Administrative Procedure Act to waive the 30-day 
delay in the effective date (5 U.S.C. 553(d)(3)) of the final rule. 
HRCP is the only entity subject to the regulations, and it has informed 
NMFS that it requests that this final rule take effect by March 2021 in 
order to prevent serious impacts that would result from any stoppage in 
the project construction schedule. Any delay of enacting the final rule 
would result in either: (1) Suspension of construction on a major road 
transport infrastructure project at significantly increased cost; or 
(2) HRCP's procedural non-compliance with the MMPA (should HRCP conduct 
pile driving and removal without an LOA), thereby resulting in the 
potential for unauthorized takes of marine mammals. Due to a project 
design change occurring in September 2020, HRCP requested to transfer a 
portion of pile installation from the rulemaking/LOA application to the 
recently issued IHA (85 FR 48153; August 10, 2020). This resulted in 
the need for submitting a revised application including re-calculation 
of estimated take. Given this delay, NMFS was unable to accommodate the 
30-day delay of effectiveness period and issue the LOA to HRCP in time 
to prevent a work stoppage and associated delay in the project 
schedule. Moreover, HRCP is ready to implement the rule immediately. 
For these reasons, the Assistant Administrator finds good cause to 
waive the 30-day delay in the effective date.

List of Subjects in 50 CFR Part 217

    Administrative practice and procedure, Marine mammals, Oil and gas 
exploration, Penalties, Reporting and recordkeeping requirements.

    Dated: March 19, 2021.
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 amended 
as follows:

PART 217--REGULATIONS GOVERNING THE TAKING AND IMPORTING OF MARINE 
MAMMALS

0
1. The authority citation for part 217 continues to read as follows:

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


0
2. Add subpart W, consisting of Sec. Sec.  217.210 through 217.219, to 
read as follows:

Subpart W--Taking and Importing Marine Mammals Incidental to 
Hampton Roads Connector Partners Construction at Norfolk, Virginia

Sec.
217.210 Specified activity and geographical region.
217.211 Effective dates.
217.212 Permissible methods of taking.
217.213 Prohibitions.
217.214 Mitigation requirements.
217.215 Requirements for monitoring and reporting.
217.216 Letters of Authorization.
217.217 Renewals and modifications of Letters of Authorization.
217.218-217.219 [Reserved]

Subpart W--Taking and Importing Marine Mammals Incidental to 
Hampton Roads Connector Partners Construction at Norfolk, Virginia


Sec.  217.210  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 in the James River between 
Norfolk, VA and Hampton, VA.


Sec.  217.211  Effective dates.

    Regulations in this subpart are effective from April 2, 2021 
through April 2, 2026.


Sec.  217.212   Permissible methods of taking.

    (a) Under an LOA issued pursuant to Sec. Sec.  216.106 of this 
chapter and 217.216, the Holder of the LOA (hereinafter ``HRCP'') may 
incidentally, but not intentionally, take marine mammals within the 
area described in Sec.  217.210(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]


Sec.  217.213  Prohibitions.

    (a) Except for the takings contemplated in Sec.  217.22 and 
authorized by an LOA issued under Sec. Sec.  216.106 of this chapter 
and 217.216, it is unlawful for any person to do any of the following 
in connection with the activities described in Sec.  217.210:
    (1) Violate, or fail to comply with, the terms, conditions, and 
requirements of this subpart or a LOA issued under Sec. Sec.  216.106 
of this chapter and 217.216;
    (2) Take any marine mammal not specified in such LOA;
    (3) Take any marine mammal specified in such LOA in any manner that 
is not authorized by the LOA; or
    (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.
    (b) [Reserved]


Sec.  217.214  Mitigation requirements.

    (a) When conducting the activities identified in Sec.  217.210(a), 
the mitigation measures contained in any LOA issued under Sec. Sec.  
216.106 of this chapter and 217.216 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 
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 
Sec. Sec.  216.106 of this chapter and 217.216. If a marine mammal 
comes within or approaches the shutdown zone, such operations shall 
cease.
    (6) HRCP shall deploy protected species observers (observers) as 
indicated in its Marine Mammal Monitoring Plan approved by NMFS.
    (7) For all pile driving activities, between one and four observers 
shall be

[[Page 17491]]

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 (e.g., fog, heavy 
rain) such that observers are unable to visibly detect marine mammals 
within the entire shutdown zone then 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 thirty-second 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 
specified in an LOA issued under Sec. Sec.  216.106 of this chapter and 
Sec.  217.216. This shall occur prior to the initiation of pile driving 
activities.
    (b) [Reserved]


Sec.  217.215  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);
    (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, estimated observable distance (if less than 
the harassment zone distance), and percentages of Level A and Level B 
harassment zones that are not visible;
    (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);

[[Page 17492]]

    (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; and
    (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.


Sec.  217.216  Letters of Authorization.

    (a) To incidentally take marine mammals pursuant to these 
regulations, 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 these regulations.
    (c) If an LOA expires prior to the expiration date of these 
regulations, 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 Sec.  217.217.
    (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 these regulations.
    (g) Notice of issuance or denial of an LOA shall be published in 
the Federal Register within thirty days of a determination.


Sec.  217.217  Renewals and modifications of Letters of Authorization.

    (a) An LOA issued under Sec. Sec.  216.106 of this chapter and 
217.216 for the activity identified in Sec.  217.210(a) shall be 
renewed or modified upon request by the applicant, provided that:
    (1) The planned specified activity and mitigation, monitoring, and 
reporting measures, as well as the anticipated impacts, are the same as 
those described and analyzed for these regulations; and
    (2) NMFS determines that the mitigation, monitoring, and reporting 
measures required by the previous LOA under these regulations 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 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 Sec. Sec.  216.106 of this chapter and 
217.216 for the activity identified in Sec.  217.210(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 preamble for these 
regulations;
    (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; and
    (C) Any information that reveals marine mammals may have been taken 
in a manner, extent or number not authorized by these regulations 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 Sec. Sec.  216.106 of 
this chapter and 217.216, 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.


Sec.  217.218-Sec.  217.219  [Reserved]

[FR Doc. 2021-06132 Filed 4-1-21; 8:45 am]
BILLING CODE 3510-22-P