Environmental Dredging and Site Improvements at Two Coastal Oregon Shipyards

Hart Crowser conducted Remedial Investigations (RI) and Feasibility Studies (FS) at two active shipyards in Coos Bay, Oregon. These shipyards are located in ecologically sensitive estuarine and wetland habitats in Coos Bay, Oregon. RI/FS activities were conducted pursuant to separate Administrative Cleanup Orders issued by the Oregon Department of Environmental Quality (DEQ). We were able to avert a Superfund listing and we successfully negotiated the Cleanup Orders with DEQ so that the RI/FS activities were focused to site contaminants; the cleanup decisions were based on appropriate risk based standards; and cleanup could proceed on realistic timelines. Primary sources of contamination include current and past activities attributed to fabrication and repair of fishing vessels, ocean tugs and barges. Waste streams generated by routine site activities include spent sandblast grit, marine antifoulants from hull paints, and petroleum sludge from barge and bilge tank cleaning. Remedial Investigation activities included: delineations and determinations of surface and subsurface sediment quality, and upland soil quality; and ecological and human health risk evaluations for site contaminants of concern. Metals and tributyltin (TBT) were identified as the chemicals of concern in sediments. In upland soils, no human health risk criteria were exceeded; however, copper and nickel were identified as the primary contaminants of concern to ecological receptors. Feasibility Studies identified appropriate remedial action alternatives and source controls to eliminate current ecological risks and prevent future re-contamination of upland soils and estuarine sediments. The selected alternatives for sediments included excavation/dredging of contaminated areas along the marine ways and natural recovery of peripheral areas. Source controls included capping of soils with asphalt; improved stormwater management with filtration vaults; wash water treatment for metal removal using a flocculation system; as well as improved best management practices at the shipyards. These projects enabled the shipyards to remain economically viable and their improved work practices will protect the sensitive habitats surrounding them.