Laserfiche WebLink
Appendix C:Previous Environmental Activities <br /> The Central Valley RWQCB agreed that MW-3 and MW-4 should be destroyed, provided that <br /> the results of one additional groundwater sampling event satisfied the monitoring well <br /> destruction criteria. The Central Valley RWQCB also recommended a final sampling event for <br /> MW-5. However, SAIC was allowed to proceed with the destruction of MW-5 without <br /> additional sampling and analysis because continued access to the well for this purpose was <br /> denied by Western Farm Service, and because the well was unaffected by crude oil from the <br /> former OVP or TAOC pipelines.13 <br /> SAIC ANNUAL 2009 GROUNDWATER MONITORING AND SAMPLING 14 <br /> Annual groundwater monitoring and sampling was performed on February 11, 2009. The <br /> oleophilic sock in well MW-I was replaced because it exhibited separate-phase oil (SPO) <br /> staining. Staining was not observed on the oleophilic sock in MW-2, and therefore the sock did <br /> not require replacement. SPO has been observed in MW-1 and MW-2 since 1999, with a total of <br /> 0.5 gallon removed from these wells as of the 2009 sampling event. <br /> The groundwater sample from MW-3 had detections of TPHd and chrysene above ESLs or <br /> WQOs. A duplicate sample from MW-3 also reported concentrations of benzo(a)anthracene, <br /> chrysene, and pyrene above ESLs or WQOs. <br /> SAIC 2008-2009 MONITORING WELL DESTRUCTION AND SOIL AND <br /> GROUNDWATER INVESTIGATION 15 <br /> SAIC completed MW-4 and MW-5 well destruction activities on August 7 and 8, 2008. In <br /> addition, SAIC advanced a total of 27 borings in three separate mobilizations (August 2008, <br /> November 2008, and March 2009)to delineate the extent of affected soil and groundwater at the <br /> site. The borings were advanced to total depths ranging from 10 to 88 feet bgs. <br /> Soil analytical results for TPHc exceeded EPA Regional Screening Levels (RSLs)16 and/or ESLs <br /> in borings SB-18, SB-20 through S13-26, S13-28, S13-29, and SB-34 with concentrations ranging <br /> from 540 mg/kg to 26,000 mg/kg. BTEX concentrations in excess of screening levels were <br /> detected in S13-21. PAHs were detected in excess of screening levels in 18 of the 27 borings. <br /> Groundwater samples were not collected from S13-20, S13-21, S13-28, S13-34, SB-38 through <br /> S13-41, and SB-43 due to the presence of SPO. TPHd were detected in excess of WQO and/or <br /> ESL screening levels in the groundwater samples from S13-18, S13-19, SB-22 through S13-25, <br /> S13-29, and SB-42 with concentrations ranging from 110 gg/L to 130,000 µg/L. PAHs were <br /> detected above screening levels in five of 16 groundwater sampling locations. BTEX were not <br /> detected above screening levels. <br /> 13.RWQCB,2007. Review of Second Quarter 2007 Groundwater Monitoring and Sampling Report—US-Can Welty Road <br /> Property,Vernalis,San Joaquin County. August 16. <br /> 14.SAIC,2009. Annual 2009 Groundwater Monitoring and Sampling Report, US Can–Welty Road, 35275 Welty Road, <br /> Vernalis, California. April. <br /> 15.SAIC,2009. Monitoring Well Destruction and Soil and Groundwater Investigation Report, US Can–Welty Road, 35275 <br /> Welty Road, Vernalis,San Joaquin County, California. September 24. <br /> 16.EPA,2008. Regional Screening Levels for Chemical Contaminants at Superfund Sites. <br /> hM2://www.epa.gov/region9/waste/sfund/pra/index.html#2r t�able. September. <br /> C-6The Benham campantes,LL[ <br /> 541C. Awhally Owned 5vtnidwy <br /> From 5cf0we to SWUM"$ <br />