Section 1 Introduction - National Marine Fisheries Service - NOAA

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NBK at Bangor EHW-1 Pile Replacement Project Final Marine Mammal Monitoring Report Section 3 Results Acoustic Results In general, underwater and airborne sound measurements collected at the WRA vessel, provided the best acoustic data for construction. However, sound measurements were taken in multiple locations inside and outside the WRA, and the distances to various sound thresholds for marine mammals were calculated using data from all available sources. Only sound levels recorded at the mid-distance (WRA vessel) and distant (raft and mid-channel vessel) locations are presented in this report. For more detailed sound pressure level results please see NAVFAC 2012. In some cases data was not available from the vessel-based sound sensors because of equipment failures/damage, transportation issues, timing limitations, environmental conditions, or communication system failures; in these cases, sound thresholds were calculated based on other sensors located inside and outside the WRA. Vibratory Pile Driving: Acoustic Results Typical vibratory pile driving during the EHW-1 resulted in sound levels that varied considerably through the driving periods. Vibratory sounds underwater were characterized by the measurement of RMS sound pressure levels. During the EHW-1 PRP there were 28 permanent steel pipe piles (12 at the walkway and 16 at Bents of the EHW-1 structure) and 8 temporary steel falsework piles which were installed using a vibratory hammer. In addition, two 24-inch steel fender piles and eight 12-inch steel fender piles were removed using a vibratory hammer and/or dead pull. Vibratory pile installation/removal occurred on 14 days between Oct 5 – 27 th . Vibratory installation occurred during parts of all of the 14 days, whereas vibratory extraction only occurred on portions of two of the days. During the installation/removal of an individual pile there were occasionally multiple vibratory recording events as a result of the pile driver being temporarily shutdown or the pile requiring additional driving at a later time. In total, 65 vibratory driving events (i.e., installation or removal of piles) were measured. Actual vibratory pile driving events during the EHW-1 lasted from less than 0.5 minutes to almost 41 minutes, and the duration of vibratory extraction events ranged from 3 minutes to 32 minutes per pile. The total duration of all vibratory driving and extraction events over the course of EHW-1 PRP was 13:52:23 (vib in 12:11:36, vib out 1:40:47) (see Table 3). Table 4 presents a summary of the average RMS sound pressure levels measured at the WRA boat and the estimated distance to the 120 dB behavioral harassment threshold for cetaceans and pinnipeds. On average, the WRA-boat sound level was 158 dB RMS (re: 1µPa) for piles less than 30-inches in diameter and 154 dB RMS (re: 1µPa) for 30-inch diameter piles. The maximum event level recorded at this location from all driving was 168 dB RMS (re: 1µPa). The maximum sound pressure level recorded approximately 10 meters from the pile, was 174 dB RMS (re: 1µPa) (NAVFAC 2012). The average sound pressure level for all 30-inch permanently installed piles, using a 10 second integration period, was 166 dB RMS (re: 1µPa) at 10 meters. Sound pressure levels were generally lower during the installation of falsework piles, which were slightly smaller (16–inch diameter), or the vibratory extraction of piles. For environmental compliance documents for the EHW-1 PRP, the near-source level used for consultations was 168 dB RMS (re: 1µPa) at 10 meters. Based on the data recorded during the EHW-1 PRP, the near-source levels used in the consultation process were close or only slightly conservative compared to the recorded levels.. Bangor, Washington 22
NBK at Bangor EHW-1 Pile Replacement Project Final Marine Mammal Monitoring Report Event Description Table 4. Summary of Underwater Sound Levels During Vibratory Pile Installation and Removal Pile Coordinates Start Time Stop Time Sensor Measured Sound Pressure Level - RMS (WRA Boat) Ave Max Calculated distance to 120 dB RMS (m) Date: 10/4/2011 Inside Pile EHW1 Lat. 47° 45.215' 9:06:33 9:10:42 1 Mid 127 129 N/A 1 Long. 122° 43.468' Down 128 131 Date: 10/5/2011 BP1 (EHW- 14) Lat. Long. 47° 45.215' 122° 43.468' 8:29:53 8:32:01 Mid Down 141 144 146 150 4,312 BP2 (EHW- 15) Lat. Long. 47° 45.215' 122° 43.468' 8:35:36 8:36:36 Mid Down 146 148 147 149 3,802 Date: 10/7/2011 RX5 Lat. Long. 47° 45.199' 122° 43.435' 9:29:17 9:34:09 Mid Down 144 145 150 152 5,462 RX6 Lat. Long. 47° 45.215' 122° 43.468' 9:40:31 9:40:53 Mid Down 150 150 153 153 5,858 RX7 Lat. Long. 47° 45.215' 122° 43.468' 9:43:30 9:43:42 Mid Down 149 149 152 152 South ± 7,000 (Land) North 7,700 RX8 Lat. Long. 47° 45.211' 122° 43.453' 14:24:18 14:33:30 Mid Down 152 154 155 156 South ± 7,000 (Land) North 10,800 RX1 Lat. Long. 47° 45.201' 122° 43.426' 15:00:31 15:08:25 Mid Down 151 153 156 159 South ± 7,000 (Land) North 10,800 FW1 Lat. Long. 47° 45.199' 122° 43.448' 16:55:37 17:02:40 Mid Down 146 147 151 151 South ± 7,000 (Land) North 10,800 FW2 Lat. Long. 47° 45.199' 122° 43.448' 17:15:49 17:19:25 Mid Down 142 145 148 150 South ± 7,000 (Land) North 10,800 FW3 Lat. Long. 47° 45.199' 122° 43.448' 17:31:49 17:36:07 Mid Down 142 144 153 153 South ± 7,000 (Land) North 10,800 FW4 Lat. Long. 47° 45.199' 122° 43.448' 17:43:36 17:46:46 Mid Down 146 146 149 154 South ± 7,000 (Land) North 10,800 Date: 10/8/2011 FW5 Lat. Long. 47° 45.204' 122° 43.461' 8:43:33 8:51:03 Mid Down 146 146 153 152 South ± 7,000 (Land) North 10,800 FW6 Lat. Long. 47° 45.204' 122° 43.461' 9:01:45 9:05:03 Mid Down 145 145 154 153 South ± 7,000 (Land) North 10,800 FW7 Lat. Long. 47° 45.204' 122° 43.461' 9:11:52 9:14:11 Mid Down 144 144 154 154 5,415 FW8 Lat. Long. 47° 45.204' 122° 43.461' 9:19:13 9:27:23 Mid Down 144 144 151 153 4,294 Date: 10/10/2011 W6 Lat. Long. 47° 45.199' 122° 43.448' 13:30:46 13:39:27 Mid Down 155 158 163 164 South ± 7,000 (Land) North 10,800 W5 Lat. Long. 47° 45.199' 122° 43.448' 13:57:17 14:03:46 Mid Down 154 157 162 164 South ± 7,000 (Land) North 10,800 W4 Lat. Long. 47° 45.199' 122° 43.448' 14:16:28 14:23:32 Mid Down 151 152 167 168 South ± 7,000 (Land) North ± 13,000 (Land) W6 - REVIB Lat. Long. 47° 45.199' 122° 43.448' 14:25:20 14:25:51 Mid Down 155 155 165 162 South ± 7,000 (Land) North ± 13,000 (Land) Bangor, Washington 23
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Section 1 Introduction - National Marine Fisheries Service - NOAA

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