Federal Register - June 29, 2021
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Source: Federal Register
Federal Register / Vol. 86, No. 122 / Tuesday, June 29, 2021 / Notices
34205
MetlakaUa Saaptana Faclmy Ratucblallma1H Project
BILLING CODE 351022C
lotter on DSK11XQN23PROD with NOTICES1
Detailed Description of Specific Activity Proposed activities included as part of the project with potential to affect marine mammals include the noise generated by vibratory removal of steel pipe piles, vibratory and impact installation of steel pipe piles, and DTH
to stabilize piles. Pile removal will be conducted using a vibratory hammer.
Pile installation will be conducted using both a vibratory and impact hammer and DTH pile installation methods.
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Piles will be advanced to refusal using a vibratory hammer. After DTH pile installation, the final approximately 10
ft of driving will be conducted using an impact hammer so that the structural capacity of the pile embedment can be verified. The pile installation methods used will depend on sediment depth and conditions at each pile location.
Pile installation and removal will occur in waters approximately 67 m 2023
ft in depth.
The project will involve the removal of 11 existing steel pipe piles 16-inch
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in diameter that support the existing multiple-float structure. The multiplefloat timber structure, which covers 8,600 square ft, will also be removed. A
new 4,800-square-ft single-float timber structure will be installed in the same general location. Six 24-in diameter steel pipe piles will be installed to act as restraints for the new seaplane float.
In addition, 12 temporary 24-in steel piles will be installed to support pile installation and removed following completion of construction.
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Figure 1--Project Location, Metlakatla, Alaska
