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|Title:||South Jetty Sediment Processes Study, Grays Harbor Washington: evaluation of engineering structures and maintenance measures|
|Authors:||Pacific International Engineering|
United States. Army. Corps of Engineers. Seattle District
Osborne, Philip D.
Wamsley, Ty V.
Arden, Hiram T.
|Publisher:||Coastal and Hydraulics Laboratory (U.S.)|
Engineer Research and Development Center (U.S.)
|Series/Report no.:||ERDC/CHL TR ; 03-4.|
Grays Harbor is located on the southwest Washington coast at the mouth of the Chehalis River, about 45 miles north of the Columbia River mouth. The harbor is 13 miles wide at its broadest point and 15 miles long from Aberdeen, WA, on the east to the entrance o the west. Two convergent rock jetties, a north jetty and a south jetty, are part of the Grays Harbor navigation project, which is a federally constructed and maintained navigation channel. Development of the channels and facilities at Grays Harbor has been a continuing process since the Rivers and Harbors Act of June 1896 authorized the construction of the south jetty. Maintenance dredging has been required after the 1990 Grays Harbor navigation improvement project was completed. The U.S. Army Engineer District, Seattle requested a study to evaluate the engineering features and maintenance measures in the vicinity of the south jetty. The south jetty sediment processes study was developed and keyed to elements of a plan of action. The purpose of the study is to evaluate the performance of engineering and maintenance measures that have been implemented to control breaching next to the south jetty, and to reduce shoreline erosion in Half Moon Bay and placement of dredged material to alleviate erosion. Another study in a series on the south jetty is in progress to document the analysis of a breached condition and assess the risk of future breaching. This report documents the history of the south jetty and related engineering structures, and reviews previous studies relevant to the acting coastal processes. It includes reviews of dredging and disposal activities associated with maintenance and new work dredging, analysis of the wave diffraction mound performance, analysis of upland and intertidal topography and nearshore bathymetry surveys, analysis of shoreline position change, identification of sediment pathways, and a sediment budget. The performance of the engineering and maintenance measures is then evaluated based on these results. The role of continued periodic nourishment activities is also assessed.
|Appears in Collections:||Technical Report|