Transmission loss for vibratory pile driving in shallow water: Modeling and field measurements for a Puget Sound location

Abstract

Measurements of the underwater noise from vibratory pile driving were collected at a marine construction site in January 2013, during which 0.76 m steel piles were driven in shallow water (less than 10 m). The sound field was simultaneously measured at three locations at distances 200 m (1 hydrophone) and 400 m (2 hydrophones) from the pile driving location and roughly 150 m to 300 m from the shore. In the Practical Spreading Model (PSM), transmission loss is 15 log10(R/R0): R is the range to which TL is calculated, and R0 is the range for a close range measurement, typically O(10 m) from the source. Models such as the PSM that do not account for bathymetric or sediment properties could not be expected to predict the anomalously high transmission loss (TL) that was observed between the 200 m location and one of the 400 m locations. Important bathymetric features (of order 10 m in range, 1 m in depth) and sedimentary properties for the area were incorporated into a Parabolic Equation model; modeled TL was compared to observed TL for third octave bands. Using a Geographic Information System tool, modeled TL was visualized for the area. [Work supported by Washington Sea Grant.]