Project Number:

3793

Predicted Underwater Sound Levels for Cape Wind Pile Driving

SERVICE:

Acoustic Modeling of Undersea Construction Sound

DESCRIPTION:

For the 450-MW Cape Wind Project, Tech performed acoustic modeling of underwater sound from the pile installation of the 130 wind turbine monopiles in Nantucket Sound. Sound power spectra were developed for an IHC S01800 impact hammer, a Menck MHU-1900S impact hammer, an APE Super Triple Kong vibratory driver, a Clamshell Dredge inside the monopile, and a Rock Drill inside the monopile. Acoustic modeling was then used to calculate the distance at which sound pressure levels for construction equipment would equal the following National Marine Fisheries Services (NMFS) thresholds to protect marine mammals and fish: 180 dBRMS re 1 uPa for potential injury. 120 & 160 dBRMS re 1 uPa for behavioral/ harassment from impulse/continuous sources. 206 dBPEAK re 1 uPa for potential injury to fish from all sources. 183 &187 dBSEL-CUM re 1 uPa2 sec for potential injury to fish below & above 2-g weight from impact pile drivers only. A graph of the frequency spectra and tables of the setback distances that will ensure compliance with NMFS criteria were provided to Cape Wind Associates for each monopile installation.

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Key Points

  • Tech performed acoustic modeling to develop a sound power spectra for numerous pieces of equipment being used for pile installation in the Nantucket Sound.
  • From the modeling, Tech was able to calculate the distance at which sound pressure levels would equal certain NMFS thresholds.