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December 22 , 1988 l <br /> Project 156-117 . 1 <br /> Pesticides DDE and DDT were detected in soil sample DH-3 <br /> under Total Threshold Limit Concentration (TTLC) conditions <br /> and are well below the California Department of Health <br /> Services (DHS ) established TTLC limits . The detected amounts <br /> are also below the Soluble Threshold Limit Concentration <br /> (STLC) limits ( see Table 2 ) . The pesticides were not <br /> detected in any of the ground water samples . <br /> Antimony, arsenic , barium, chromium, cobalt , copper, lead, <br /> mercury, nickel , thallium, vanadium, and zinc were detected <br /> below the DHS TTLC limits in soil sample DH-2 ( 2 . 5 feet ) <br /> analyzed under TTLC conditions . The amounts detected are <br /> also below the STLC limits with the exception of arsenic, <br /> barium, nickel , thallium and vanadium. However, since these <br /> levels do not exceed ten times the STLC limits , a waste <br /> extraction test (WET) is not warranted (see Table 2 ) . , <br /> Arsenic, barium, chromium, cobalt, copper, lead, mercury, <br /> nickel , thallium, vanadium, and zinc were detected in the <br /> —lground water sample from MW-2 . The amounts of copper, <br /> mercury, and zinc detected are below Federal EPA standards <br /> for drinking water. The amounts of arsenic , barium, <br /> chromium, and lead detected exceed the EPA standards for <br /> drinking water , however, the amounts detected are well below <br /> the EPA EP Toxicity levels for hazardous waste (see Table 3 ) . <br /> Presently there are no established EPA drinking water <br /> standards for cobalt, nickel , thallium, or vanadium. All <br /> laboratory analyses are presented in Appendix B. <br /> Conclusions/Recommendations <br /> Results of the chemical analyses indicate the presence of <br /> arsenic , barium, chromium and lead exceeding EPA drinking <br /> water standards in the shallow ground water extracted from <br /> MW-2 . The elevated concentrations of these constituents does <br /> not appear to be attributable to an on-site source , and may <br /> reflect background water quality in the shallow aquifer <br /> beneath the site , particularly due to the subject site ' s <br /> proximity to the San Joaquin Delta. <br /> Laboratory analysis has revealed that the subsurface soils <br /> and shallow ground water do not contain compounds for which <br /> analyses were performed in concentrations considered to be <br /> hazardous , therefore ; the drill hole cuttings and ground <br /> water contained during the field investigation can be <br /> disposed of on-site. <br /> In accordance with your request and as required by the SJLHD <br /> monitoring well permit process , a copy of this report has <br /> been forwarded to Diane Hinson of the SJLHD. <br /> GBetac_4ssociates Am. c Q� <br />