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lu <br /> FINDINGS AND CONCLUSIONS <br /> i <br /> -� Based on LH's Preliminary Site Assessment of Cho fcrmor underground tank site - <br /> i - at 402 South Wilson Way In Stockton,the Following cencluslons can be made:, <br /> 1. The geologic formation beneath the slte Is primarily composed of <br /> Intermittent clay and sand layers the water bearing gene appears to he <br /> V a sand layer located beneath the silt, The water surface elevation was <br /> easured at approximately 57 foot below the ground surface In December of <br /> 1989. <br /> J •J 2. Based on the observed water surface elevations,groundwater flaw appears ' <br /> to be In approximately an easterly direction across the site. <br /> �. Apprexlmateiy li mum{c 1pal wetrr hells are located within a ane mlFe radius <br /> of the site. Of these, only 3 wells aGpear to to down gr ad lent of the <br /> site,the closest well being appresimatoty I300 foot down gradient. water . <br /> quality records show no evidence of petroleum hydrocarbon Contamination <br /> r� <br /> In these—10P water wells. <br /> '-� 4. Groundwater samples collected from MW1, Hwl and MW4 show trace <br /> (.` concentrations of BTSSE and TPH as gasoline. - - <br /> t,, <br /> S. Groundwater samples collected from HW2 and HW5 coat aincd relativeiy high <br /> concentrations of dissolved BT115E and TPH as PaoliIle' No phase separated <br /> petroleum hydrocarbons are observed, <br /> a'l 6. Sell samples obtained from TDO,T87,TDe,TBg;.4 and Hwy Indicate trace <br /> or nondetect4ble concentrations of BT25E and TPH as gasoline,orders of <br /> magnitude below the allowable LOFT Harual guidelines for residual petroleum <br /> hydrocarbons. <br /> 7. Soil llsamples collected from T85 indicate levels of B7x&E and TPN as <br /> �j gasgne In excess of the LUF7 Manual guidelines, Thls suggests a snit <br /> _ concern In the northwest corner of the site. <br /> rte' 8. Sell takensamples collected from the excavated soil stockpile and drum samples <br /> U trace conte t ratlonss oFCgT%5E and TPH as gasoline orderrsBoI magnitude below <br /> thdLNF7 Manual guide7lnex. According ko 4he leaching-potential analysis <br /> L,' ' and the general risk appraisal, -sing this soli as backfill £n the open <br /> excavatson would he acceptable, <br /> fff v f� <br /> „. `.. <br /> li <br />