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California Department of Transportation March 13, 2001 <br /> Shop 10 Maintenance Station, Stockton, California Project No 400296-01 <br /> under chain-of-custody protocol The samples were transferred to Associated Laborato- <br /> ries (AL) in Orange, California via United Parcel Service (UPS) Purged and <br /> decontamination water generated during sampling activities were transferred into la- <br /> beled, reconditioned 55-gallon drums The drums were left on-site to be maintained by <br /> Caltrans <br /> 43 Laboratory Analysis <br /> The groundwater samples were submitted for analysis to AL, a State of California-certified <br /> hazardous waste analytical laboratory Samples were analyzed for TPH-G and TPH-D, using <br /> method EPA 8015 (modified) Samples were analyzed for BTEX, meths 1 tertiary-butyl ether <br /> (MTBE), tertiary-amyl-methyl ether (TAME), isopropyl ether (DIPS), tertiary butyl (TBA), <br /> ethyl-tertiary-butyl ether (ETBE), and volatile organic compounds (N,OCs) using method <br /> EPA 8260B A summary of the past and present laboratory results for the groundwater sam- <br /> ples is presented in Table 1 Copies of laboratory results and chain-of-custody documents are <br /> included in Appendix B <br /> 5. SUMMARY AND CONCLUSIONS <br /> rNinyo & Moore measured depth-to-groundwater and sampled eleven wells at the site on Sep- <br /> tember 13, 2000 Groundwater elevation data indicates that the groundwater flow is to the east <br /> beneath the site with a hydraulic gradient of 0 005 feet per foot Comparatively, groundwater <br /> measurements recorded during the last monitoring event in June 2000 indicated groundwater <br /> movement beneath the site was to the east with a gradient of 0 009 feet per foot The groundwa- <br /> ter elevation has decreased in all wells since the last sampling event Groundwater elevations <br /> have decreased in monitoring well MW-9 by 2 92 ft , MW-11 by 2 96 ft , MW-12 by 2 92 ft , <br /> MW-13 by 2 93 ft , MW-14 by 2 88 ft , MW-16 by 2 91 fl , MW-19 by 2 87 ft , MW-20 by 2 97 <br /> ft , MW-24 by 2 89 ft , MW-25 by 2 86 ft and VM-1 by 2 88 ft <br /> ILaboratory data indicates changes in concentrations in many of the compounds analyzed in sam- <br /> ples taken from various wells on site since the last monitoring event <br /> 0296 01r shop 10!%L 3Q'_000 doc 4 <br />