Location: Portland, Oregon
Client: Oregon Department of Environmental Quality
Contract Value: $940,000
The Nuway Oil site is located in northeast Portland, Oregon and is a former used oil re-refining facility. The Oregon Department of Environmental Quality selected AEC through a competitive bid process to dredge 1,800 cy of impacted sediment from the Columbia River Slough and excavate another 12,000 cy of bank soil followed by complete shoreline restoration. Once all submittals were finalized and AEC deployed strict erosion and sediment control methods, AEC used standard mechanical excavation methods from the shoreline to essentially pull the near shore sediment and bank soils from north to south upward towards the bank. We subcontracted a crane and derrick operation to perform dredging of the approximately 1,800 cubic yards of sediment from within the Slough. We placed the dredge spoils, excavated bank excavation spoils, and hot spot excavation soil into an upland stockpile or assessment area, for dewatering and measurement. The Engineer was responsible for sampling the stockpiles to determine the proper disposition of the stockpiled material. Approximately 12,000 tons of sediment and soil material was excavated and placed in the assessment cells. The scope called for construction of an onsite disposal pit in the same area that was previously used as an oil storage lagoon and material with lower concentrations of contamination was placed in the onsite disposal area. However, stockpiled spoils material not meeting onsite disposal criteria (e.g., onsite hot spots) was disposed of at an appropriate offsite disposal facility. Once all the contaminated soil and sediment was removed and disposed of properly, AEC began excavating the existing southern bank of Whitaker Slough and reconstructing the bank with imported soils, riprap, geogrid, geotextlie and vegetation. Non-hazardous materials that were confirmed as clean, were used in the installation of the new bank. In total, we constructed 450 lineal feet of new bank along the Slough which involved the placement of a rip rap toe and the installation of an engineered bank which included layered tie-back materials and replanting.