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I" 29 April 2005 ' AGE-NC Project No. 98-0440 Page'7 of 18 J In January 2002,.grab ground water samples were collectedTr6 i borings B8'and B9 t 601feet bsg. _TPH-g was detected just above reporting limits in the grab water samples'at concentration and 88 µg/l, respectively.,TPH=d was defected in the water. sample collected from B9 at, a coriceritration`of'140`µg/1. Ethylbenzerie and`totaT xylene's-were detected in the sample.from B8 at r' I concentrations,of L2 µg/l and 1.3 µgll, respectively. Toluene, ethylbenzene and total xylenes,were detected in the water sample collected-from boring B9 at,concentrations of 0.62 µg/l;0.,72,4g11 and 4.3 µg/l,`respectively:-No other analytes including•benzene were detected at'or above laboratory reporting limits in the grab ground water samples analyzed. Based on the current area bounded by wells. MW-1 through MW-,12, the lateral extent-of the dissolved petroleum-hydrocarbon plume is defined;-additionally, the current concentrations'.of dissolved.TPH and BTEX compounds (benzene) detected at the former UST area in samples from well MW-2 have declined to 1%.of 2.5 % their respective highest concentrations. The dissolved TPH-g concentration trends for well MW-2 and MW-5 are depicted In Appendix D. TPH-g-and benzene.impact to ground water,is depicted in plane view in Figures 7 and 8. The vertical extent is Igenerally defined by.the very low concentrations of TPH-g; low,concentration.of TEX.'below drinking water standards and absence of benzene in the 60-foot grab ground water samples. . 5.0. POTENTIAL IMPACT ON NEARBY'SURFACE AND GROUND WATER ITypically, ground water would represent the migration medium forrcontaminants over significant horizontal distances.However,sites located in up-gradient or cross-gradient directions from the site are not IikeIy to be negatively irtipacted,by the site. In addition, first encountered ground water is I used,for drinking or irrigation and all ground water'in the State of California is considered to„be of potential'beneficial use. i The water supply for the Strong Property located at 5157 West Business Loop 205 was supplied.by a domestic well"(DW-5157)'"23Q feet west of the site. According'to Mr. Mik'e.Strong.tlie water line , I' extending t6'5.157 from this domestic well was ruptured.in'1998 and subsequently,capped off. At :. the present there is no-water being supplied to.5157 West:Business Loop 205: This domestic well currently supplies drinking watertothe adjacent properties,5161 and 5163 West Business Loop 205. The domestic water wells located at 5225 and 5055 West Business Loop 205 are the most vulnerable I for poteiitial�imp act from the"hydrocarbon plume from the'former UST area located at the Strong .Property. DW-5055 is located- directly down-gradient of the former UST area. .However, the dissolved contaminant plume does not extend beyond wells MW-3-and.MW-10 towards DW-5225- �. nor"does it extend beyond wells"MW-7; MW-8, MW-11 and,MW-12 towards DW-5055. Analysis. of quarterly water samples from the domestic;well have been non=detect for petroleumhydrocarbons. IAdvanced GcoEnvironmental,Inc.