§ 217.94 Mitigation requirements. When conducting the activities identified in § 217.90(c), the mitigation measures contained in any LOAs issued under § 216.106 of this chapter and § 217.96 must be implemented. These mitigation measures shall include but are not limited to: ( a ) *Time restriction.* In-water construction and demolition work shall occur only during daylight hours.
( b ) *Establishment of monitoring and shutdown zones.* ( 1 ) For all relevant in-water construction and demolition activity, the Navy shall designate Level A harassment zones with radial distances as identified in any LOA issued under § 216.106 of this chapter and § 217.96.
( 2 ) For all relevant in-water construction and demolition activity, the Navy shall designate Level B harassment zones with radial distances as identified in any LOA issued under § 216.106 of this chapter and § 217.96.
( 3 ) For all in-water construction and demolition activity, the Navy shall implement a minimum shutdown zone of a 10-m radius around the pile. If a marine mammal comes within or approaches the shutdown zone, such operations shall cease.
( c ) *Monitoring visibility.* Pile driving shall only take place when the shutdown and Level A zones are visible and can be adequately monitored. If conditions (*e.g.,* fog) prevent the visual detection of marine mammals, activities with the potential to result in Level A harassment shall not be initiated. If such conditions arise after the activity has begun, pile driving or pile removal activities shall be halted if the 10-m shutdown zone is not visible.
( d ) *Shutdown measures.* ( 1 ) The Navy shall deploy three protected species observers (PSOs) to monitor marine mammals during in-water pile driving and pile removal. One PSO shall be located on land and two shall be located in a boat to monitor the farther locations.
( 2 ) Monitoring shall take place from 15 minutes prior to initiation of pile driving or removal activity through 30 minutes post-completion of pile driving or removal activity. Pre-activity monitoring shall be conducted for 15 minutes to ensure that the shutdown zone is clear of marine mammals, and pile driving or removal may commence when observers have declared the shutdown zone clear of marine mammals. In the event of a delay or shutdown of activity resulting from marine mammals in the shutdown zone, animals shall be allowed to remain in the shutdown zone (*i.e.,* must leave of their own volition) and their behavior shall be monitored and documented. Monitoring shall occur throughout the time required to drive or remove a pile. A determination that the shutdown zone is clear must be made during a period of good visibility (*i.e.,* the entire shutdown zone and surrounding waters must be visible to the naked eye).
( 3 ) If a marine mammal approaches or enters the shutdown zone, or if a marine mammal not specified in the LOAs enters the Level B harassment zone, or if the take of a marine mammal species or stock has reached the take limits specified in any LOA issued under § 216.106 of this chapter and § 217.96 and enters the Level B harassment zone, all pile driving or removal activities at that location shall be halted. If pile driving or removal is halted or delayed due to the presence of a marine mammal, the activity may not commence or resume until either the animal has voluntarily left and been visually confirmed beyond the shutdown zone or fifteen minutes have passed without re-detection of the animal.
( 4 ) The Navy shall implement shutdown measures if the number of authorized takes for any particular species reaches the limit under the applicable LOA and if such marine mammals are sighted within the vicinity of the project area and are approaching the Level B harassment zone during in-water construction or demolition activities.
( e ) *Soft start.* ( 1 ) The Navy shall implement soft start techniques for impact pile driving. The Navy shall conduct an initial set of three strikes from the impact hammer at 40 percent energy, followed by a 1-minute waiting period, then two subsequent three strike sets.
( 2 ) Soft start shall be required for any impact driving, including at the beginning of the day, and at any time following a cessation of impact pile driving of 30 minutes or longer.