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samples were 10 and 13 mg/kg, which is within normal background <br /> levels for Pleistocene alluvial sediment in the Stockton area. <br /> Lead was detected at a somewhat elevated concentration of 58 mg/kg <br /> in the stockpile sample, suggesting the possibility that background <br /> concentrations had been increased by the introduction of organic <br /> lead from a petroleum leak. Therefore, this sample was re-run for <br /> soluble lead using the California WET-test (STLC) . This test <br /> detected soluble lead at a concentration of 5 . 8 mg/kg. Normally, <br /> soil that contains soluble lead in excess of 5 . 0 mg/kg should be <br /> disposed of at a suitable landfill . <br /> 6.0 CONCLUSIONS <br /> The tank removal, sampling, and laboratory analysis were performed <br /> in accordance with the requirements of the Central Valley Regional <br /> Water Quality Control Board and San Joaquin County Environmental <br /> Health Division. No contamination was detected beneath the UST, but <br /> an elevated lead concentration was detected in soil removed from <br /> the excavation. Therefore, Upgradient Environmental recommends that <br /> Hoblitzell & Associates transport the stockpiled soil to an <br /> appropriate disposal facility and forward disposal documentation to <br /> San Joaquin County EHD. Alternatively, the stockpile could be <br /> resampled more thoroughly to provide a better measure of the <br /> average lead concentration. Samples could be collected at a rate of <br /> 1 per 25 cubic yards and composited to one or two samples for <br /> analysis . After disposing of or resampling the stockpile, H & A <br /> should backfill the UST excavation and request that a case closure <br /> letter be issued to the property owner. <br /> 7 .0 REMARKS AND SIGNATURE <br /> The recommendations contained in this report represent a <br /> professional opinion, and are based on currently available <br /> information, part of which has been supplied by the client. <br /> The interpretations have been arrived at in accordance with <br /> currently accepted geologic and engineering practices at this time <br /> and location. Other than this, no warranty is intended. <br /> Respectfully Submitted, <br /> Uoaradient Environmental Consultants <br /> Date <br /> Vict gg , Ph. D. <br /> Reg E tid q st #3475 <br />