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Dara Farrell

Predoctoral Research Associate I

Email

farrell@apl.washington.edu

Phone

206-616-5346

Department Affiliation

Acoustics

Publications

2000-present and while at APL-UW

The underwater sound field from vibratory pile driving

Dahl, P.H., D.R. Dall'Osto, and D.M. Farrell, "The underwater sound field from vibratory pile driving," J. Acoust. Soc. Am., 137, doi:10.1121/1.4921288, 2015.

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1 Jun 2015

Underwater noise from vibratory pile driving was observed using a vertical line array placed at range 16 m from the pile source (water depth 7.5 m), and using single hydrophones at range 417 m on one transect, and range 207 and 436 m on another transect running approximately parallel to a sloping shoreline. The dominant spectral features of the underwater noise are related to the frequency of the vibratory pile driving hammer (typically 15–35 Hz), producing spectral lines at intervals of this frequency. The mean-square pressure versus depth is subsequently studied in third-octave bands. Depth and frequency variations of this quantity observed at the vertical line array are well modeled by a field consisting of an incoherent sum of sources distributed over the water column. Adiabatic mode theory is used to propagate this field to greater ranges and model the observations made along the two depth-varying transects. The effect of shear in the seabed, although small, is also included. Bathymetric refraction on the transect parallel to the shoreline reduced mean-square pressure levels at the 436-m measurement site.

Modeling and visualization of the underwater sound field associated with underwater pile driving

Farrell, D.M., and P.H. Dahl, "Modeling and visualization of the underwater sound field associated with underwater pile driving," J. Acoust. Soc. Am., 132, 2061, doi:10.1121/1.4755595, 2012.

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1 Sep 2012

As communities seek to expand and upgrade marine and transportation infrastructure, underwater noise from pile driving associated with marine construction is a significant environmental regulatory challenge. This work explores results of different transmission loss models for a site in Puget Sound and the effect of improved understanding of modeling on the extents of zones of influence. It has been observed that most of the energy associated with impact pile driving is less than about 1000 Hz. Here, analysis of the spectral content of pile driving noise is undertaken to ascertain the optimal surrogate frequency to model the broadband nature of the noise. Included is a comparison of a normal mode model, which is motivated by work presented by Reinhall and Dahl [JASA 130, 1209 (2011)], with other methods. A GIS (Geographic Information System) tool, ArcMap, is used to map the sound level over the bathymetry, which has proved to be a useful way of visualizing the impact of the noise.

Transmission loss and range, depth scales associated with impact pile driving

Dahl, P., P. Reinhall, and D. Farrell, "Transmission loss and range, depth scales associated with impact pile driving," Proceedings, 11th European Conference on Underwater Acoustics, 2-6 July, Edinburgh, 1860-1867 (Institute of Acoustics, 2012).

2 Jul 2012

Acoustics Air-Sea Interaction & Remote Sensing Center for Environmental & Information Systems Center for Industrial & Medical Ultrasound Electronic & Photonic Systems Ocean Engineering Ocean Physics Polar Science Center
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