Quiero saber acerca de...

8495

Federal Register / Vol. 86, No. 23 / Friday, February 5, 2021 / Notices TABLE 1SUMMARY OF PILE DRIVING ACTIVITIES FOR SFWF AND SFECContinued Pile driving method
Pile size
Vibratory

19.5 m long/0.95 cm thick Sheet pile.

Number of piles 80

Strikes/pile
Duration/pile
Number of piling days

18 hours
18 hours

Installation: 13.
Removal: 13.

Approximation; the actual number will be based on final engineering design.

High-Resolution Geophysical Surveys The HRG survey activities would be supported by vessels of sufficient size to accomplish the survey goals in each of the specified survey areas. Up to four vessels may work concurrently throughout the area considered in this proposal. HRG surveys would occur throughout the 12-month period of effectiveness for the proposed IHA. HRG
equipment will either be deployed from remotely operated vehicles ROVs or mounted to or towed behind the survey vessel at a typical survey speed of approximately 4.0 knots kn 7.4 km per hour. The geophysical survey activities proposed by South Fork Wind would include the following:
Shallow Penetration Sub-bottom Profilers SBPs; Compressed HighIntensity Radiated Pulses CHIRPs to map the near-surface stratigraphy top 0
to 5 m 0 to 16 ft of sediment below seabed. A CHIRP system emits sonar pulses that increase in frequency over time. The pulse length frequency range can be adjusted to meet project variables. These are typically mounted on the hull of the vessel or from a side pole.
Medium penetration SBPs Boomers to map deeper subsurface stratigraphy as needed. A boomer is a broad-band sound source operating in the 3.5 Hz to 10 kHz frequency range.
This system is typically mounted on a sled and towed behind the vessel.
Medium penetration SBPs Sparkers to map deeper subsurface stratigraphy as needed. A sparker creates acoustic pulses from 50 Hz to 4
kHz omni-directionally from the source that can penetrate several hundred meters into the seafloor. These are typically towed behind the vessel with adjacent hydrophone arrays to receive the return signals.

Parametric SBPs, also called sediment echosounders, for providing high density data in sub-bottom profiles that are typically required for cable routes, very shallow water, and archaeological surveys. These are typically mounted on the hull of the vessel or from a side pole.
Ultra-short Baseline USBL
Positioning and Global Acoustic Positioning System GAPS to provide high accuracy ranges to track the positions of other HRG equipment by measuring the time between the acoustic pulses transmitted by the vessel transceiver and the equipment transponder necessary to produce the acoustic profile. It is a two-component system with a hull or pole mounted transceiver and one to several transponders either on the seabed or on the equipment.
Multibeam echosounder MBES to determine water depths and general bottom topography. MBES sonar systems project sonar pulses in several angled beams from a transducer mounted to a ships hull. The beams radiate out from the transducer in a fanshaped pattern orthogonally to the ships direction.
Seafloor imaging sidescan sonar for seabed sediment classification purposes, to identify natural and manmade acoustic targets resting on the bottom as well as any anomalous features. The sonar device emits conical or fan-shaped pulses down toward the seafloor in multiple beams at a wide angle, perpendicular to the path of the sensor through the water. The acoustic return of the pulses is recorded in a series of cross-track slices, which can be joined to form an image of the sea bottom within the swath of the beam.
They are typically towed beside or behind the vessel or from an autonomous vehicle.

Table 2 identifies all the representative survey equipment that operate below 180 kilohertz kHz i.e., at frequencies that are audible and have the potential to disturb marine mammals that may be used in support of planned geophysical survey activities, and are likely to be detected by marine mammals given the source level, frequency, and beamwidth of the equipment. The operational frequencies for MBES and Sidescan Sonar that would be used for these surveys are greater than 180 kHz, outside the general hearing range of marine mammals likely to occur in SFWF and SFEC. Parametric sub-bottom profilers operate at high frequencies with narrow beamwidths, resulting in Level A
harassment and Level B harassment threshold isopleth distances less than 4
m. No harassment exposures can be reasonably expected from the operation of these sources; therefore, the Innomar parametric SBPs were not carried forward in the application analysis.
USBLs are instruments that are used to locate the positions of other HRG
equipment; the sources characteristics and functionality of USBLs are not expected to result in Level A
harassment or Level B harassment.
These equipment types are, therefore, not considered further in this notice.
For discussion of acoustic terminology, please see the Potential Effects of Specified Activities on Marine Mammals and their Habitat and Estimated Take sections.
The make and model of the listed geophysical equipment may vary depending on availability and the final equipment choices will vary depending upon the final survey design, vessel availability, and survey contractor selection. Selection of equipment combinations is based on specific survey objectives.

jbell on DSKJLSW7X2PROD with NOTICES2

TABLE 2SUMMARY OF REPRESENTATIVE HRG SURVEY EQUIPMENT
HRG equipment category Shallow Sub-bottom Profilers.

VerDate Sep<11>2014

Specific HRG equipment
Source level dB rms
Source level dB 0-peak
216
28
424
0.712

195

24

20

6

176
179

71
80

3.4
9

2
8

ET 216 2000DS or 3200 top unit.
ET 424
ET 512

19:54 Feb 04, 2021

Jkt 253001

PO 00000

Typical pulse duration ms
Operating frequency range kHz
Frm 00007

Fmt 4701

Sfmt 4703

Beamwidth degrees
E:FRFM05FEN2.SGM

05FEN2

Pulse repetition rate