ARCHIVED REPORTS XR0000254 - Laserfiche WebLink

Home Browse Search

California Department of Transportation June 19, 2001 ' Stockton Maintenance Station, Stockton, California Project No 400296001 43 Laboratory Analysis The groundwater samples were submitted for analysis to AL, a State of Cali fornia-certiled hazardous waste analytical laboratory Samples were alsoanalyzed for TPH-G and TPH-D, using method EPA 8015 (modified) Samples were analyzed for BTEX, methyl tertiary- butyI ether (MI BE), tertiary-amyl-methyl ether (TAME), isopropyl ether (DIPE), tertiary butyl (TBA), ethyl-tertiary-butyl ether (ETBE), and volatile organic compounds (VOCs) using method EPA 8260B A summary of the past and present laboratory results for the groundwater samples is presented in Table I Copies of laboratory results and chain-of- custody hain-ofcustody documents are included in Appendix B 5 SUMMARY AND CONCLUSIONS Ninyo & Moore measured depth-to-groundwater and sampled fourteen wells at the site on De- cember 12-14, 2000 Groundwater elevation data indicates that the groundwater flows to the southeast beneath the site with a hydraulic gradient of 0 002 feet per foot Comparatively, groundwater levels taken during the last monitoring event in September 2000 indicate the same flow direction and hydraulic gradient Groundwater elevation has increased in all of the on-site wells since the last monitoring event Groundwater elevations have increased in monitoring well MW-I by 0 53 ft , MW-2 by 0 54 ft , MW-3 by 0 54 ft , MW-4 by 0 56 ft , MW-5 by 0 57 ft, MW-6 by 0 47 ft , MW-7 by 0 52 ft , MW-8 by 0 53 ft , MW-9 by 0 49 ft , MW-10 by 0 60 ft , MW-I 1 by 0 52 ft , MW-12 by 0 49 ft , VW-1 by 0 60 ft and VW-2 by 0 84 ft Laboratory analytical data has indicated changes in many of the compounds analyzed in samples taken from various wells on site since the September 2000 monitoring event In well MW-1, Benzene concentration increased from non-detectable levels to 6 4 micrograms per liter (pg/1) Total xylene concentration increased from non-detectable levels to 21 pg/1 In well MW-2, TPH-G concentration increased from non-detectable levels to 180 pIg l Benzene concentration increased from 6 8 [ig 1 to 29 µg/1 Total xylene concentration increased from non- detectable levels to 25 pg/l �I�GtILI�I&�®®CS't 0290 o i r Stockton F v z.IQ z000 dor 4