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Federal Register / Vol. 86, No. 23 / Friday, February 5, 2021 / Notices Verification section below. The attenuation system would likely be a single bubble curtain, but may include one of the following or some combination of the following: A double BBC, Hydro-sound Damper, and/or Noise Abatement System. South Fork would also have a second back-up attenuation device e.g., additional bubble curtain or similar available, if needed, to achieve the targeted reduction in noise levels that would result in the measured Level A
harassment and Level B harassment isopleths corresponding to those modeled assuming 10 dB attenuation, pending results of sound field verification testing.
If South Fork Wind uses a bubble curtain, 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 for the full circumference of the ring, and the weights attached to the bottom ring shall ensure 100 percent mudline contact. No parts of the ring or other objects shall prevent full mudline contact. South Fork Wind would require that construction contractors train personnel in the proper balancing of airflow to the bubblers, and would require that construction contractors submit an inspection/performance report for approval by South Fork Wind within 72 hours following the performance test. Corrections to the attenuation device to meet the performance standards would occur prior to impact driving. If South Fork Wind uses a noise attenuation device other than a BBC, similar quality control measures would be required.

Cofferdam Installation and Removal Clearance and Exclusion Zones South Fork Wind would implement visual monitoring of the clearance zones for 30 minutes prior to the initiation of ramp-up of vibratory piling equipment Table 25. During this period, the clearance zone will be monitored by the PSOs, using the appropriate visual technology. Ramp-up may not be initiated if any marine mammals is detected within its respective exclusion zone. If a marine mammal is observed within a clearance zone during the preclearance period, ramp-up may not begin until the animals has been observed exiting its respective clearance zone or until an additional time period has elapsed with no further sighting i.e., 15 minutes for small odontocetes and seals, and 30 minutes for all other species.

TABLE 25PROPOSED CLEARANCE AND EXCLUSION ZONES DURING INSTALLATION AND REMOVAL OF A TEMPORARY
COFFERDAM
Level A
harassment zone m SEL

Species
Low-Frequency Cetaceans:
Fin whale
Minke whale
Sei whale
Humpback whale
North Atlantic right whale
Blue whale
Mid-Frequency Cetaceans:
Sperm whale
Atlantic spotted dolphin
Atlantic white-sided dolphin
Common dolphin
Rissos dolphin
Bottlenose dolphin
Long-finned pilot whale
High-Frequency Cetaceans:
Harbor porpoise
Phocid Pinnipeds in Water:
Gray seal
Harbor seal

Level B
harassment zone m SPL

Pre-start clearance zone m
Exclusion zone m
Vessel separation distance m
1,470
1,470
1,470
1,470
1,470
1,470

36,766
36,766
36,766
36,766
36,766
36,766

1,500
1,500
1,500
1,500
1,500
1,500

1,500
1,500
1,500
1,500
1,500
1,500

100
100
100
100
500
100

36,766
36,766
36,766
36,766
36,766
36,766
36,766

1,500
100
100
100
100
100
100

1,500
50
50
50
50
50
50

100
50
50
50
50
50
50

63

36,766

100

100

50

103
103

36,766
36,766

150
150

125
125

50
50

SEL = cumulative sound exposure level in units of decibels referenced to 1 micropascal squared second; SPL = root-mean-square sound pressure level in units of decibels referenced to 1 micropascal.

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Shutdown of Vibratory Pile Driving An immediate shutdown of vibratory pile driving equipment must be implemented if a marine mammal is sighted entering or within its respective exclusion zone after cofferdam installation has commenced.
Resumption of vibratory pile driving can begin if the animal has been observed exiting its respective exclusion zone or an additional time period has elapsed without a resighting i.e., 15
minutes for small odontocetes and seals and 30 minutes for all other species. If
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a species for which authorization has not been granted, or, a species for which authorization has been granted but the authorized number of takes have been met, approaches or is observed within the exclusion zone, shutdown would be required.
HRG Surveys Clearance and Exclusion Zones South Fork Wind would implement a 30-minute pre-clearance period of the clearance zones prior to the initiation of ramp-up of HRG equipment Table 26.

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During this period, the clearance zone will be monitored by the PSOs, using the appropriate visual technology.
Ramp-up may not be initiated if any marine mammals is within its respective clearance zone. If a marine mammal is observed within a clearance zone during the pre-clearance period, ramp-up may not begin until the animals has been observed exiting its respective clearance zone or until an additional time period has elapsed with no further sighting i.e., 15 minutes for small odontocetes and seals, and 30
minutes for all other species.

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