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Scope of Work:
¨ Prior to any sediment removal, the pond was drained and incoming flows were diverted directly to the Hudson River. The primary influent of approximately 800 gpm was diverted with 4” submersible pumps. Secondary influences from several springs within the pond were diverted to a low point within the pump and pumped to the river with a second set of pumps.
¨ Two culvert pipes, which conveyed the primary influent, were jetted to remove fine sediments which restricted flow into the pond.
¨ The remedial design required the removal of bank soils and several feet of pond sediments. Additional sediment removal was necessary in one area, in order to construct a new berm on a competent base. Total sediment and bank soil removal was over 1,500 cubic yards.
¨ Sediment removal was generally performed using a 45’ longstick excavator. During excavation, sediments were solidified in the pond with lime prior to loading onto site trucks. At a nearby staging area, the material was further solidified until it passed paint filter analysis. In order to minimize the remediation costs, disposal methods utilized both off-site thermal treatment and on-site processing in the owner’s cement kiln. Ultimately, over 80% of the sediment was treated on-site.
¨ Reconstruction and upgrades to the pond required the construction of a new, 5’ berm which divided the pond into upper and lower retention areas. Culvert piping was installed through the berm in order control the upper pond elevation and provide for basic oil-water separation.
¨ Additional oil spill controls included the installation of 100’ of floating boom on the upper section of the pond. All spill control components and upgrades were installed with the intent of simplifying maintenance and removal of future sediment buildup.