Remedial Action Report Construction Phase

Home Browse Search

8 investigation indicated that the extent of petroleum-impacted soil left in place was delineated and that the contaminated soil does not pose a threat to human health or the environment (Century West 1998d). 4.0 REMEDIAL ACTION APPROACH Construction phase remedial actions were conducted in accordance with Century West's Remedial Action Plan (RAP), which includes a Health and Safety Plan, Sampling and Analysis Plan, Dewatering Plan, and Waste Management Plan (Century West 1999a). In general, the DEQ's soil matrix cleanup rules (OAR 340-122-320 through 340-122-360), RBCA cleanup rules (OAR 340-122-244 through 340-122-250), and site development plans were used to guide site investigations and remedial actions completed during the pre-construction and construction phases of work. The soil matrix cleanup levels for gasoline and diesel contamination at the site, determined prior to construction (Century West 1998c) are 80 milligrams per kilograms (mg/kg) and 500 mg/kg, respectively. The exposure assessment included in the RBCA Tier I evaluation completed for the former Chevron properiy, previously discussed in Section 3.3, was determined to be applicable to the overall site, and therefore was utilized to determine appropriate RBCA Tier 1 RBSLs. The following flow chart illustrates the remedial excavation strategy: REMEDIAL EXCAVATION STRATEGY CONSTRUCTION PHASE Soil Inspection/PID No Clean soil disposal orsoil Contaminated? left in place (may need confirmation samples) Yes Contaminated Soil Requires Yes Removal for Construction~ Off-Site Disposal No Sample Yes Contaminated Soil Left in TPH Concentretion < Matrix Place No Constituents Concentrations < RBSL? Yes Contaminated Soil Left in Place No Continue Remedial Excavation Construction Phase - Remedial Ac[ions - 5- 4080600127 Courthouse Squaze November 9, 1999