Federal Register - October 13, 2021
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Source: Federal Register
56872
Federal Register / Vol. 86, No. 195 / Wednesday, October 13, 2021 / Proposed Rules
TABLE 7NMFS TECHNICAL GUIDANCE 2020 USER SPREADSHEET INPUT TO CALCULATE PTS ISOPLETHS FOR
VIBRATORY PILE DRIVING
User spreadsheet inputVibratory Pile Driving Spreadsheet Tab A.1 Vibratory Pile Driving Used.
14-in steel Hpile Source Level RMS SPL
Weighting Factor Adjustment kHz
Number of piles within 24-hr period
Duration to drive a single pile min
Propagation xLogR
Distance of source level measurement m
22.5-in Zshaped sheet piles
158
2.5
12
10
15
10
31.5-in Zshaped sheet piles
163
2.5
10
13
15
10
163
2.5
8
13
15
10
TABLE 8NMFS TECHNICAL GUIDANCE 2020 USER SPREADSHEET INPUT TO CALCULATE PTS ISOPLETHS FOR IMPACT
PILE DRIVING
User spreadsheet inputImpact Pile Driving Spreadsheet Tab E.1 Impact Pile Driving Used.
22-in Zshaped piles Source Level Single Strike/shot SEL
Weighting Factor Adjustment kHz
Number of strikes per pile
Number of piles per day
Propagation xLogR
Distance of source level measurement m
31.5-in Zshaped piles
180
2
530
10
15
10
30-in pile
181
2
530
8
15
10
42-in pile
181
2
530
2
15
10
181
2
530
4
15
10
TABLE 9NMFS TECHNICAL GUIDANCE 2020 USER SPREADSHEET OUTPUTS TO CALCULATE LEVEL A HARASSMENT
PTS ISOPLETHS
User spreadsheet output PTS isopleths m Level A harassment
Sound source level at 10 m
Activity
Low-frequency cetaceans
Mid-frequency cetaceans
Highfrequency cetaceans
Phocid
Otariid
Vibratory Pile Driving/Removal 14-inch H-pile
22.5-in Z-shaped sheet piles
31.5-in Z-shaped sheet piles
158 SPL
163 SPL
163 SPL
6.8
15.5
13.4
0.6
1.4
1.2
10.1
23.0
19.8
4.2
9.4
8.1
0.3
0.7
0.6
68.1
68.4
27.2
43.1
2,281.5
2,292.4
909.7
1,444.1
1,025.0
1,029.9
408.7
648.8
74.6
75.0
29.8
47.2
Impact Pile Driving
jspears on DSK121TN23PROD with PROPOSALS1
22.5-in Z-shaped sheet piles
31.5-in Z-shaped sheet piles
30-in pile
42-in pile
180
181
181
181
SEL/190
SEL/196
SEL/196
SEL/196
Level B Harassment Utilizing the practical spreading model, NMFS determined underwater noise will fall below the behavioral effects threshold of 120 dB rms for marine mammals at the distances shown in Table 10 for vibratory pile driving.
With these radial distances, the largest
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SPL
SPL
SPL
SPL
1,915.4
1,942.5
763.7
1,212
Level B harassment zone calculated was 7,356 m for sheet piles. However, this distance would be truncated due to the presence of intersecting land masses.
For calculating the Level B harassment zone for impact driving, the practical spreading loss model was used with a behavioral threshold of 160 dB rms. The
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maximum radial distance of the Level B
harassment zone for impact piling equaled 2,512 m for 30-in piles, 42-in piles and 31.5-in sheet piles. Table 10
below provides all Level B harassment radial distances m and ensonified areas km2 during the Navys proposed activities.
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13OCP1
