ARCHIVED REPORTS XR0000192 - Laserfiche WebLink

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California Department of Transportation August 17, 1999 Shop 10 Maintenance Station, Stockton, California Project No 103872-02 I • ITotal xylenes decreased in well MW-19 from 4 ug/l to non detect since December 1998 1 Benzene decreased in well MW-24, from to 3 1 ug/1 to non detect TPH-G decreased in well VM-1 from 25,700 ug/l to 3,700 ug/l and TPH-D decreased from 6,100 ug/l to non detect levels Concentrations of benzene have decreased from 4,600 ug/l to non de- tect, toluene has decreased from 980 ug/l to 86 ug/l, ethylbenzene has increased from 53 ug/1 to 917 ug/1, and concentt ations of total xylenes have decreased from 2,600 ug/l to 608 ug/l In well VM-2, TPH-G increased in concentration from 44,700 ug/l to 64,000 ug/l and concenti a- tions of TPH-D decreased from 4,100 ug/l to non detect levels VM-2 had decreased Iconcentrations of BTEX, except for ethylbenzene, which increased since April 1999 Benzene decreased from 7,500 ug/l to 2,250, toluene decreased from 2,700 ug/l to 1,180 ug/l, ethylben- zene increased from 120 ug/l to 245 ug/l, and concentrations of total xylenes decreased from 2,940 ug/l to 572 ug/l According to laboratory analytical data for 8260B, other VOCs that were detected during the current groundwater sampling event are 1,2-dichloroethane, 1,2,4-trrmethylbenzene, 1,3,5- 1 trrmethylbenzene, isopropylbenzene, naphthalene, n-butylbenzene, tert-butylbenzene, and allyl 1 chloride A duplicate sampl (MW-32) as taken at MW-12 and the duplicate analysis was identical to the Iprimary samples A ank (TB-2) was placed inside the cooler during transport to AL and analyzed using method 8260B No compounds were detected in the trip blank sample 1 6. RECOMMENDATIONS Based on the results of the Second Quarter 1999 groundwater monitoring analytical results, ' which indicated elevated concentrations of TPH-G, TPH-D and/or BTEX, Ninyo & Moore rec- ommends that quarterly groundwater monitoring continue at the site I shop IQdoc 5