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Billy Wasson August 18, 2000 Page 2 of 4 2) During the environmental assessment and construction phases, a total of thirteen general areas of suspected contamination were identified. Each area potentially contained multiple sources of contamination, such as existing or suspected underground storage tanks (USTs), dry wells, vehicle hoists, or was simply identified as an area of suspected contamination. 3) A total of nine USTs were decommissioned by removal by CJE Consultants and Constructers, Inc. 4) As part of the decommissioning and remediation process, a total of 2,640 tons of petroleum contaminated soils (PCS) were excavated and disposed of at Riverbend Landfill in McMinnville, Oregon. 5) A pocket of approximately 385 cubic yards of PCS exceeded the Soil Matrix II Cleanup standards (gasoline-80 ppm, diesel-500 ppm). Constituent data indicated the concentrations remaining within the pocket were below the Risk-Based Conective Action (RBCA) Tier I table values and, therefore, the pocket does not pose a significant risk to human health or ~~ the environment. ~ 6) The regional groundwater flow direction across the site is towards the northwest. The groundwater seasonally fluctuates between 10 feet and 16 feet below ground surface. 7) During the dewatering operations, approximately 1,413,645 gallons of water were pumped from the excavation and sumps into the local storm drain system, which dischazges to the Willamette River. This discharge operation was conducted under an NPDES 1500A pernut, issued on August 18, 1998 (DEQ WQ file #109691/A). 8) During a11 mass excavation activities, Century West Engineering (CWE), as required, had a licensed Soil Matrix supervisor on-site to field-screen excavated soils. 9) A portable rock crusher was setup on-site as a means to process the rock during the excavation phase, reduce hauling costs, and provide suitable fill material during the construction phase. Approximately 22,146 tons of rock were processed for recycling. Of that amount, 5,698 tons were re-used on-site. Note: CWE has acknowledged the potential for the subsurface parking garage to flood during periods of extreme precipitation. If such an event were to occur, the Department would expect Marion County to take appropriate action, which may include, but not be limited to, sampling, determining the risk, and preventing exposure. Also, the Department understands the County has ~ no intention of using any groundwater via on-site wells, and all water needed will be supplied by the City of Salem. ,