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Clayton <br /> I'lli101 1\TAl <br /> CDN.iUl1A�T5 <br /> When KEI installed the groundwater monitoring well (which has been <br /> abandoned) near the former location of the UST in 1986, groundwater was <br /> analyzed for gasoline, benzene, toluene, ethylberizene, and xylene, all of which <br /> were below detectable limits. Clayton reviewed the report generated from that <br /> study and found that the location plan included in the report was somewhat <br /> misaligned. It appears that they probably installed the well on the south, or <br /> upgradient,side of the UST. This might explain why they did not find detectable <br /> limits of hydrocarbons at that time. <br /> — <br /> Hydrocarbon Oil and Grease <br /> Hydrocarbon oil and grease were below detection limits in all three wells. <br /> Or anochlorine Pesticides and PCBs <br /> Pesticides and PCBs were below detection limits in all three wells. <br /> 5.0 CONCLUSIONS <br /> Our findings and conclusions are as follows: <br /> • Benzene was not detected in any of the soil or water samples. <br /> • Pesticides and PCBs were below detection limits in all three wells. <br /> • Low levels of petroleum products were detected in soil in MW-3. The <br /> maximums of these levels were: <br /> w - Total petroleum hydrocarbons (TPH) as gasoline 68 parts per million (ppm) <br /> - Toluene 50 parts per billion (Ppb) <br /> - Xylenes 730 ppb <br /> - Ethylbenzene 350 ppb <br /> The groundwater in-MW-3 is at 8.39 feet below ground surface and the <br /> affected soil is located less than 5 feet from the groundwater. Due largely to <br /> the shallow groundwater, Category 3 of the Leaking Underground Fuel Tank <br /> (LUFT)Field Manual would typically apply. Clayton will consult with the San <br /> Joaquin County,:Environmental Health Division, and with the Central Valley <br /> Regional Water Quality Control Board (RWQCB) on the status of this site. <br /> • The concentration of hydrocarbon oil and grease was 250 ppm in a soil sample <br /> from MW-3. There are no set action levels for oil and grease; however, when <br /> concentrations exceed 100 ppnn the RWQCB's Recommendations for the <br /> Evaluation and Investigation of USTs requires a soil/groundwater investigation. <br /> This study satisfies the RWQCB requirements. The 3.00 ppm level is not a <br /> cleanup level. The cleanup level is determined by assessing tire potential for <br /> soil contamination to impact groundwater. <br /> Hydrocarbon oil and grease were also detected in soil samples from MW-1 and <br /> MW-2, but are within acceptable levels as determined by the RWQCB. <br /> -6- <br />