Section 217.174 - Mitigation requirements(a) When conducting the activities identified in § 217.171(a) , the mitigation measures contained in any LOA issued under §§ 216.106 of this chapter and 217.176 must be implemented. These mitigation measures must include but are not limited to:(1) A copy of any issued LOA must be in the possession of the Navy, supervisory construction personnel, lead protected species observers (PSOs), and any other relevant designees of the Holder operating under the authority of this LOA at all times that activities subject to this LOA are being conducted.(2) The Navy will follow mitigation procedures as described in this section. Should environmental conditions deteriorate such that marine mammals within the entire shutdown zone would not be visible (e.g., fog, heavy rain, night), the Holder shall delay pile driving and removal until observers are confident marine mammals within the shutdown zone could be detected.(3) The Navy will ensure that construction supervisors and crews, the monitoring team, and relevant Navy staff are trained prior to the start of all activities subject to this rule, so that responsibilities, communication procedures, monitoring protocols, and operational procedures are clearly understood. New personnel joining during the project will be trained prior to commencing work.(4) The Navy, construction supervisors and crews, PSOs, and relevant Navy staff will avoid direct physical interaction with marine mammals during construction activity. If a marine mammal comes within 10 m of such activity, operations will cease and vessels will reduce speed to the minimum level required to maintain steerage and safe working conditions, as necessary, to avoid direct physical interaction.(5) The Navy will employ PSOs and establish monitoring locations as described in this rule and the Marine Mammal Monitoring Plan. The Navy will monitor the project area to the maximum extent possible based on the required number of PSOs, required monitoring locations, and environmental conditions.(6) Monitoring will take place from 30 minutes prior to initiation of pile driving activity (i.e., pre-start clearance monitoring) through 30 minutes post-completion of pile driving activity.(7) If a marine mammal is observed entering or within the shutdown zones indicated in this rule, pile driving activity must be delayed or halted. If pile driving is delayed or halted due to the presence of a marine mammal, the activity may not commence or resume until either the animal has voluntarily exited and been visually confirmed beyond the shutdown zone or 15 minutes have passed without re-detection of the animal.(8) The Navy will establish shutdown zones for all pile driving activities. Shutdown zones are limited to 150 m from the point of noise generation. Any remaining area within estimated Level A harassment zones shall be considered part of the "disturbance zone," i.e., the Level B harassment zone and, where present, the Level A harassment zone (PTS onset) beyond 150 m from the point of noise generation. For activities where the estimated Level A (PTS onset) harassment zones are smaller than 150 m, the disturbance zone shall include the entire region of influence (ROI), i.e., estimated Level A and Level B harassment zones). Work may proceed without cessation while marine mammals are in the disturbance zone and marine mammal behavior within the disturbance zone will be monitored and documented.(9) The Navy will conduct monitoring to include the area within the Level B harassment zones (areas where SPLs are equal to or exceed the 160 dB rms threshold for impact driving and the 120 dB rms threshold during vibratory pile driving (disturbance zone).(10) Pre-start clearance monitoring will be conducted during periods of visibility sufficient for the lead PSO to determine that the shutdown zones are clear of marine mammals. Pile driving may commence following 30 minutes of observation when the determination is made that the shutdown zones are clear of marine mammals.(11) If pile driving is delayed or halted due to the presence of a marine mammal, the activity may not commence or resume until either the animal has voluntarily exited and been visually confirmed beyond the shutdown zone indicated or 15 minutes have passed without re-detection of the animal.(12) The Navy will use soft start techniques when impact pile driving. Soft start requires contractors to provide an initial set of three strikes from the hammer at reduced energy, followed by a 30-second waiting period. Then two subsequent reduced-energy strike sets would occur. A soft start will be implemented at the start of each day's impact pile driving and at any time following cessation of impact pile driving for a period of 30 minutes or longer. Soft start is not required during vibratory pile driving activities.(13) Pile driving activity must be halted upon observation of either a species entering or within the harassment zone, for which incidental take is not authorized, or a species for which incidental take has been authorized but the authorized number of takes has been met. 87 FR 885 , 5/15/2022, through 5/14/2027