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Federal Register / Vol. 86, No. 33 / Monday, February 22, 2021 / Notices Description of the Specified Activities and Anticipated Impacts
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The Navys planned activities include installation of temporary dolphin piles for construction of the caisson seat floatin, completion of the caisson seat foundation, and construction of a temporary blast wall. The Navy planned to install the guide dolphin piles in February 2021, prior to the expiration of the initial IHA; however, due to unforeseen delays, these piles are now scheduled to be installed in March 2021. Additionally, the installation of sheet piles to complete the caisson seat foundation is scheduled to conclude on February 25, 2021, although if there are any unanticipated weather or equipment delays, this activity might not be completed prior to the expiration of the initial IHA. Finally, construction of a temporary blast wall was not specifically analyzed in the 2019 IHA, but will involve the installation of a comparatively small number in relation to the initial IHA of similar or smaller size steel sheet and pipe piles using installation methods identical to those described in the 2019 IHA. The location and nature of the activities, including the types of equipment planned for use, are nearly identical to those described in the initial IHA.
Similarly, the anticipated impacts are identical in nature though significantly lower in number to those described in the initial IHA. Also, NMFS anticipates the take of only two of the five species of marine mammals described in the 2019 IHA harbor seals and gray seals by Level A harassment and Level B
harassment incidental to underwater noise resulting from construction associated with the proposed activities.
The following documents are referenced in this notice and include important supporting information:
Reissued 2019 IHA 84 FR 67261;
December 9, 2019;
2019 final IHA 84 FR 24476; May 28, 2019;
2019 proposed IHA 843 FR 13252;
April 4, 2019;
2019 IHA application, references cited, and previous public comments received available at https
www.fisheries.noaa.gov/national/
marine-mammal-protection/incidentaltake-authorizations-constructionactivities.
Detailed Description of the Activity The Navy proposes to modify and expand Dry Dock 1 at Portsmouth Naval Shipyard because dimensional limitations currently impede operations and maintenance. To minimize impacts on dry dock operations during
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construction, the overall project is being constructed in phases. The first element, construction of a superflood basin, is scheduled to occur in six phases;
activities associated with first two phases, and one activity from Phase 3
installation of the caisson seat float-in were described and analyzed in the 2019 IHA. Phases 1 and 2, planned to be completed under the initial IHA, included site reconnaissance, field measurements, contractor submittals and general mobilization activities Phase 1, and construction of the southern closure, construction of the caisson seat float-in and foundation, Berth 1 and 11 improvements, Dry Dock 1 utility improvements, and dredging Phase 2. Schedule delays precluded installation of the caisson seat float-in;
therefore, the Navy included this activity in the renewal request.
To construct the caisson seat float-in, the Navy would use vibratory pile driving to install six temporary dolphins, comprised of twelve, 30-inch in diameter steel pipe piles a reduction in size from the 36-in diameter steel pipe piles analyzed for this activity in the 2019 IHA.
To construct the remaining portion of the caisson seat foundation, the renewal request includes the installation of twenty 27-in sheet piles using a combination of vibratory and impact pile driving, as described in the initial IHA. The 2019 IHA analyzed the potential for Level A harassment and Level B harassment from installation of twenty 24-in sheet piles using the identical installation methods; the size of the sheet pile included in the renewal request is slightly larger and the source levels used to model distances to the Level A harassment and Level B
harassment isopleths are accordingly slightly higher see Estimated Take section, Table 1. However, although the sheet pile size is slightly larger, the number of 27-in sheet piles 20
associated with installation of the caisson seat foundation included in the renewal request is identical in number to that planned for the caisson sear foundation and also a small subset of the total number 320 of 24 in sheet piles included in the initial IHA.
Finally, the Navy proposes to construct a temporary blast wall, comprised of 15, 30-in steel pipe piles and 70 25-in sheet piles installed using vibratory pile driving only. This wall would be located within the project area, across the opening of the existing Dry Dock 1 between Berth 1 and Berth 11A and opposite the caisson seat, described in the proposed initial IHA
84 FR 13252; April 4, 2019. For comparison, the initial IHA included
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vibratory installation of 48, 36-in steel pipe piles and 320 24-in sheet piles.
Therefore, the renewal request includes nearly identical pile sizes steel pipe and sheet and identical installation method to those described and included in the initial IHA.
A detailed description of the construction activities for which take is proposed here may be found in the Federal Register notice of proposed IHA
for the 2019 authorization 84 FR 13252;
April 4, 2019. As stated above, the location and nature of the pile driving operations, including the type and size of piles and the methods of pile driving, are identical or nearly identical to those analyzed in the 2019 IHA. The proposed IHA renewal would be effective from the date of issuance to February 27, 2022 i.e., one year after the expiration of the initial IHA, although all construction proposed in the renewal request would be completed between March 1, 2021 and March 31, 2021.
Description of Marine Mammals A description of the marine mammals in the area of the activities for which authorization of take is proposed here, including information on abundance, status, distribution, and hearing, may be found in the Federal Register notice for the proposed IHA for the 2019
authorization 84 FR 13252; April 4, 2019. NMFS has reviewed recent draft Stock Assessment Reports, information on relevant Unusual Mortality Events, and other scientific literature. NMFS
has preliminarily determined that there is no new information that affects which species or stocks have the potential to be affected or the pertinent information in the Description of the Marine Mammals in the Area of Specified Activities contained in the supporting documents for the 2019 IHA.
Potential Effects on Marine Mammals and Their Habitat A description of the potential effects of the specified activity on marine mammals and their habitat for the activities for which take is proposed here may be found in the Federal Register notices for the proposed initial IHA 84 FR 13252; April 4, 2019. NMFS
has reviewed recent draft Stock Assessment Reports, information on relevant Unusual Mortality Events, and other scientific literature, and determined that neither this nor any other new information affects our initial analysis of impacts on marine mammals and their habitat.
Estimated Take A detailed description of the methods and inputs used to estimate take for the
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