ARCHIVED REPORTS XR0000221 - Laserfiche WebLink

Home Browse Search

California Department of Transportation June 29, 2001 Shop 10 Maintenance Station, Stockton, California Project No 400296001 beled, reconditioned 55-gallon drums The drums were left on-site to be maintained by Caltrans 4.3 Laboratory Analysis The groundwater samples were submitted for analysis to AL, a State of California-certified hazardous waste analytical laboratory Samples were analyzed for TPH-G and TPH-D, using EPA method 8015 (modified) Samples were analyzed for BTEX, MTBE, tertiary-amyl- methyl ether (TAME), isopropyl ether (DIPE), tertiary butyl (TBA), ethyl-tertiary-butyl ether (ETBE), and volatile organic compounds (VOCs) using EPA method 8260B A sum- mary of the past and present laboratory results for the groundwater samples is presented in Table 1 Copies of laboratory results and chain-of-custody documents are included in Ap- pendix B 5. SUMMARY AND CONCLUSIONS Ninyo & Moore measured depth-to-groundwater and sampled ten wells at the site on March 20- 21, 2001 Groundwater elevation data indicates that the groundwater flow is to the east beneath the site with a hydraulic gradient of 0 006 feet per foot Comparatively, groundwater measure- ments recorded during the last monitoring event in December 2000 indicated groundwater movement beneath the site was to the east with a gradient of 0 004 feet per foot The groundwa- ter elevation has increased in all wells since the last sampling event Groundwater elevations have increased in monitoring well MW-9 by 1 78 ft , MW-11 by 127 ft , MW-12 by 1 81 ft , IMW-13 by 184 ft , MW-16 by 1 7 ft , MW-19 by 184 ft , MW-20 by 1 73 ft , MW-24 by 3 63 ft , MW-25 by 124 ft and VM-1 by 181 ft ILaboratory data indicates changes in concentrations in marry of the compounds analyzed in sam- ples collected from various wells on site since the last monitoring event In well MW-13, TPH-G concentration decreased from 250 µg11 to non-detectable levels I i I 0296-OlrnhoploDrft IQ01 do 4 11ord,&