Remedial Action Report Construction Phase

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Groundwater quality in Remediated Areas 2, 6, 18, 19, 22, and 23 was assessed by pumping from Sumps 1 through 6 for at least 24 hours prior to collecting water samples for laboratory analysis. Water samples were analyzed for total petroleum hydrocarbons-diesel range (NWTPH-Dx) analysis using the DEQ-approved methods and BTEX using EPA Method 8020 or 8021. Select samples were additionally analyzed for total lead using EPA Methods 200.7 and 6010. Laboratory reports and chain-of-custody documentation for all water samples collected during construction phase remedial actions are provided in Appendix D. 4.6 Underground Storage Tanks During the construction phase, nine USTs (labeled UST-1, UST-2, UST-3, and UST-9 through 14) were decommissioned by removal in accordance with DEQ (OAR 340-122-305 through 355) and local requirements. CJ Environmental of Turner, Oregon was retained to provide UST- decommissioning contractor services. During pre-construction, UST-1, UST-2, and UST-3 were decommissioned in place to preserve the structural integrity of the paving on High Street and potential underground utilities. Based on the final building design, these USTs were removed during the construction phase. Section 5.1 provides additional details regarding the removal of UST-1, UST-2, and UST-3. All USTs decommissioned during the construction phase were cleaned on site by the contractor prior to transport for metal recycling. A copy of CJ Environmental's UST decommissioning report for UST-l, UST-2, and UST-3 is provided in Appendix E and includes disposal receipts and DEQ UST decommissioning forms. Copies of the disposal receipts and DEQ UST decommissioning forms for UST-9 through UST-14 are provided in Appendices F. Table 1 provides general details for each of the USTs decommissioned during the construction phase. 5.0 CONSTRUCTION PHASE REMEDIAL ACTIONS During pre-construction, 17 areas (Areas 1 through 17) were designated with suspected or confirmed subsurface contamination (Century West 1998b). During the construction phase, seven new areas (Areas 18 through 24) with subsurface contamination were identified. In addition, further investigation and remedial excavation were conducted in Areas 2, 3, 6, 7, 9, and 10 during the construction phase. Figure 4 shows the location of the areas in which remedial actions were completed during the construction phase. Photographs of the construction phase remedial actions are provided in AppendiY G. A summary of the field activities and the analytical results are provided in Sections 5.1 through 5.11 below. Construction Phase - Remedial Actions - 9- 4080600127 Courthouse Squarc November 9, 1999