Accession Number : ADA597877


Title :   Characterization of Underwater Sounds Produced by Trailing Suction Hopper Dredges During Sand Mining and Pump-out Operations


Descriptive Note : Final rept.


Corporate Author : ENGINEER RESEARCH AND DEVELOPMENT CENTER VICKSBURG MS ENVIRONMENTAL LAB


Personal Author(s) : Reine, Kevin J ; Clarke, Douglas ; Dickerson, Charles ; Wikel, Geoff


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a597877.pdf


Report Date : Mar 2014


Pagination or Media Count : 109


Abstract : Underwater sounds were characterized for three trailing suction hopper dredges (TSHD) during the removal of 3.1 million yd3 of sand from an offshore borrow area and during offloading of the escavated sediment at the pump-out stations in support of the Wallops Island, Virginia Beach Stabilization Project. Sounds were recorded simutaneoulsy at two depths, 3 and 9.1 m from the surface. Sound sources included sediment removal, pump-out of material, pump-out of clear water during pipe flushing, and transit to the borrow site (hopper empty) and to the pump-out stations fully loaded. Received and 1/3-octave Sound Pressure Levels (dB re 1 Pa, rms) are reported for each sound source. Source Levels (dB re 1 Pa-1m, rms) were back-caculated using fitted regression (15.788LogR). Source Levels (SL) ranged from 161.3 dB to 176.7 dB re 1 Pa-1m rms. Highest SL were obtained for the dredge Liberty, which is nearly twice the size (e.g. hopper volume, displacement) of the dredges Padre and Dodge Islands. Sounds emitted during transit produced the highest SL, whether the hopper was empty or full. Attenuation to ambient was dependent on the sound source, and ranged from 0.85 km (flushing pipes) to 2.65 km during transit with the hopper at maximum capacity.


Descriptors :   *UNDERWATER SOUND , DREDGING , FLUSHING , PIPES , SEDIMENTS


Subject Categories : Acoustics


Distribution Statement : APPROVED FOR PUBLIC RELEASE