Section 1 Introduction - National Marine Fisheries Service - NOAA

NBK at Bangor EHW-1 Pile Replacement Project Final Marine Mammal Monitoring Report
Buffer Zone. The buffer zone included all areas where the underwater or airborne SPLs
generated by vibratory pile driving were anticipated to equal or exceed the Level B (behavioral
disturbance) Harassment criteria for marine mammals (120 dB re 1μPa - underwater noise; 90 or
100 dB re 20μPa – airborne noise thresholds for the harbor seal, and all other seals and sea lions,
respectively). For vibratory pile installation and removal activities, modeling predicted a 120 dB
threshold distance of 8.6 miles (13.8 km) to the north in Hood Canal, and 4.2 miles (6.8 km) to
the south, for an affected area of 40.3 km 2 . The distance to the 100 dB threshold during
vibratory installation and removal was modeled at 30 ft (9 m) from the pile, and the 90 dB
threshold was modeled to extend 95 ft (29 m) from the pile. Measured threshold distances are
described in the Acoustic Results section.
Due to the difficulty of effectively monitoring such a large area, the U.S. Navy and NMFS
agreed that the monitored zone would include the area north, south, and west of the construction
area equivalent to the width of the Hood Canal 1.5 miles (2.4 km) (Figure 4). This area was
monitored for the presence of marine mammals before, during, and after pile installation and
removal activities. Boat captains and MMOs were equipped with vessel-mounted and hand-held
GPS units in order to ensure correct positioning and effective coverage of shutdown and buffer
zones.
Observer Monitoring Locations
In order to properly monitor shutdown and buffer zones, MMOs were positioned at various
vessel- and land-based vantage points, taking into consideration security, safety, and space
limitations at the NBK at Bangor waterfront. Three monitoring vessels were positioned inside
the WRA in addition to the construction-related vessels (e.g., barges, tugs, etc.). One monitoring
vessel was also stationed outside the WRA. Inside the WRA, MMOs were occasionally placed
on the construction barge when: (1) complete MMO coverage could not be accomplished any
other way, and/or (2) when the hydrophones located on the barge needed to be repositioned or
otherwise maintained. As described previously, the MC was stationed on or near the
construction barge, and served as an additional MMO when needed. When an MMO was on a
barge, appropriate protective gear was required and worn at all times. After the appearance of
ESA-listed Steller sea lions in the WRA in early October, two MMOs were stationed at Delta
Pier (one at Delta Pier South, the other at Delta Pier North, Figure 5) on all construction days in
order to monitor the behavior, number, and position of these animals during construction
activities.
The following boat locations (Figure 3) were identified to provide adequate visual coverage
during all construction activities:
Near-field Boat Locations:
North Monitoring Boat: Small boat vantage point within the WRA that monitored the
injury zone and behavioral disturbance zone to the north of each pile location. This boat
accommodated one MMO and two marbled murrelet observers and was also used as a
monitoring platform for the TPP. When being used to conduct EHW-1 PRP monitoring,
during vibratory installation and removal activities, the boat was stationary and
positioned at a location to provide the best vantage point.
Bangor, Washington 9