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Federal Register / Vol. 86, No. 156 / Tuesday, August 17, 2021 / Notices IHA. The take authorized for this action consists of a subset of the overall take previously authorized and discussed in greater detail in the final 2018 IHA 83
FR 30406; June 28, 2018 and final modified 2020 IHA 85 FR 86538;
December 30, 2020.
Description of Mitigation, Monitoring and Reporting Measures Mitigation Requirements The required mitigation, monitoring, and reporting measures included as requirements in this authorization are identical to those included in the Federal Register notice announcing the issuance of the modified 2020 IHA 85
FR 86538; December 30, 2020, and the discussion of the least practicable adverse impacts included in that document remains accurate. All mitigation, monitoring, and reporting measures in the modified 2020 IHA 85
FR 86538; December 30, 2020 are carried over in this renewal IHA and summarized here:
Timing RestrictionsTo minimize the number of fish exposed to underwater noise and other construction disturbance, in-water work will occur during the in-water work window previously described in the proposed renewal 86 FR 38025; July 18, 2021
when ESA-listed salmonids are least likely to be present July 16 to January 15; USACE, 2015.
All in-water construction activities will occur during daylight hours
sunrise to sunset except from July 16
to September 15, when impact pile driving will only occur starting two hours after sunrise and ending two hours after sunset, to protected foraging marbled murrelets during the nesting season April 15September 23.
Sunrise and sunset are to be determined based on National Oceanic and Atmospheric Administration data, which can be found at http
www.srrb.noaa.gov/highlights/sunrise/
sunrise.html.
Soft-StartThe use of a soft-start procedure is believed to provide additional protection to marine mammals by warning or providing a chance to leave the area prior to the hammer operating at full capacity, and typically involves a requirement to initiate sound from the hammer at reduced energy followed by a 30-second waiting period, then two subsequent reduced energy strike sets. The reduced energy of an individual hammer cannot be quantified because it varies by individual drivers. Also, the number of strikes will vary at reduced energy because raising the hammer at less than full power and then releasing it results in the hammer bouncing as it strikes the pile, resulting in multiple strikes.
A soft-start procedure will be used for impact pile driving at the beginning of each days in-water pile driving or any time impact pile driving has ceased for more than 30 minutes.
Establishment of Shutdown Zones and Disturbance ZonesTo the extent
possible, the Navy will record and report on any marine mammal occurrences, including behavioral disturbances, beyond 100 meters m;
328 feet ft for concrete pile installation. The Navy will monitor and record marine mammal observations within zones and extrapolate these values across the entirety of the Level B
harassment zone as part of the final monitoring report.
The shutdown zones are based on the distances from the source predicted for each threshold level. Different functional hearing groups for pinnipeds were evaluated. The shutdown zones for phocids were based on the maximum calculated Level A harassment radius for pinnipeds during installation of concrete piles with impact techniques.
These actions serve to protect marine mammals, allow for practical implementation of the Navys marine mammal monitoring plan and reduce the risk of a take. The shutdown zone during any non-pile driving activity will always be a minimum of 10 m 33 ft to prevent injury from physical interaction of marine mammals with construction equipment.
During all pile driving, the shutdown, Level A harassment, and Level B
harassment zones as shown in Table 3
will be monitored out to the greatest extent possible with a focus on monitoring within 100 m for concrete pile installation.

TABLE 3SHUTDOWN, LEVEL A HARASSMENT, AND LEVEL B HARASSMENT ISOPLETHS DURING IMPACT DRIVING OF
CONCRETE PILES FOR PINNIPEDS
Level B
harassment isopleth meters
Marine mammal group
Harbor seal
Sea Lions

Level A
harassment isopleth meters
46
46

19
1

Minimum monitoring zone for concrete piles
Shutdown zone meters 35
15

100 meters.1

khammond on DSKJM1Z7X2PROD with NOTICES

1 The Navy has noted in their renewal application that they will be monitoring a 100 meter radius from the project site, as practicable, in addition to the specified Level A and B harassment isopleths and the Shutdown Zone for each marine mammal group.

The isopleths delineating shutdown, Level A harassment, and Level B
harassment zones during impact driving of all concrete piles are shown in Table 3. The shutdown, Level A harassment, and Level B harassment isopleths for concrete impact driving remain unchanged from the notice of the issuance of the initial 2018 IHA 83 FR
30406; June 28, 2018 and modified 2020 IHA 85 FR 86538; December 30, 2020. Note that the Shutdown Zone is larger than the Level A harassment isopleth for harbor seals and sea lions.
The Navy may perform hydroacoustic monitoring during activities discussed
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in this action. If hydroacoustic monitoring is performed, the radii of the disturbance zones may be adjusted if insitu acoustic monitoring is conducted by the Navy to establish actual distances to the thresholds for a specific pile type and installation method. However, any proposed acoustical monitoring plan must be pre-approved by NMFS. The results of any acoustic monitoring plan must be reviewed and approved by NMFS before the radii of any disturbance zones may be revised.
Harbor seal-specific mitigationAs described in the proposed renewal 86
FR 38025; July 18, 2021, PSOs had
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reported up to eight individually identifiable harbor seals that were frequenting the project site and believed to be habituated by varying degrees to in-water construction activities. Based on the monitoring report provided by the Navy with their renewal application, a ninth seal has been noted in the area;
however this seal has not been noted as an individual seen daily and therefore does not necessitate any changes to the harbor seal-specific mitigation measures discussed below.
Even with a 35 m shutdown zone during impact driving, the Navy is still concerned that they would experience
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