ARCHIVED REPORTS XR0000249 - Laserfiche WebLink

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' California Department of TransportationFebruary24, 2000 Stockton Maintenance Station, Stockton, California Project No 103872-02 ' In well MW-5, benzene concentrations decreased from 29 µg/l to non-detect levels, total xylene concentrations decreased 22 µg11 to non-detect, and ethylbenzene decreased from 9 4 µg/1 to non- detect ' TPH-G and total xylene concentrations decreased in well MW-6 from 290 pg/l and 36 µg/l, re- spectively, to non-detect levels ' In well VW-1 concentrations of TPH-G increased from 420 µg/l to 600 µg/1 ' In well VW-2 concentrations of TPH-G increased from 4,300 gg/l to 7,800 µg/1 and TPH-D in- creased from 300 to 500 µg/l Benzene decreased from 1,270 µg/1 to 873 µg/l, toluene increased from 98 pg/l to 164 µg/1, ethylbenzene increased from 399 to 439 µg/l, and total xylenes in- creased from 869 pg/l to 1,180 gg/1 MTBE concentrations decreased from 32 pg/l to non-detect jlevels According to laboratory analytical data using EPA method 8260B additional compounds were detected in samples from various on-site wells These compounds include napthalene, 1,2,4- trim ethylbenzene, n-butylbenzene, isopropylbenzene, tert-butylbenzene, 1,3,5-trimethylbenzene, 1,2-dichloroethane, n-propylbenzene, and p-isopropylbenzene 6. RECOMMENDATIONS Based on the results of the Fourth Quarter 1999 groundwater monitoring analytical results, which indicated elevated concentration of TPH-G, TPH-D, and BTEX Ninyo & Moore recommends that quarterly groundwater monitoring continue at the site 7. LIMITATIONS The environmental services described in this report have been conducted )n general accordance with current regulatory guidelines and the standard-of-care exercised by environmental consult- ants performing similar work in the project area No other warranty, expressed or implied, is • stocklon(toe 5 V " V