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. :�.. WNW Gayton E�VIFo.vt tiiAL _. crr�suuntirs - Executive S arnmaryi Clayton Environmental Consultants, Inc., was retained by Orchard Supply Hardware to instA three monitoring wells to sample and analyze soil and groundwater at the northeast corner of macArlhur Drive and Grant Line Road in Tracy, Califomi,E. This study was authorized by Mr. Mike I- Tourette, director of real estate for Orchard Supply Hardware. The locations of the three monitoring wells are shown in Figure 2. MW-3 was installed adjacent to and downgradient of the farmer location of the gasoline underground storage tank (UST) (Figure 2). MW-1 was installed at the northwest corner of the property to monitor a UST located west of the subject site at Leprino Cheese Company. MW-2 was installed at the northeast corner of the property to complete the triangle so that groundwater gradient could be calculated. Our findings and conclusions are as follows: • Benzene was not detected in any of the soii or water samples. • Pesticides and PCBs were below detection limits in all three wells. • 1.ow levels of petroleum products were detected in soil in ?AW-3. The maximums of these levels were: - Total petroleum hydrocarbons (TPH) as gasoline 68 parts per million (ppm) - Toluene 50 parts per billion (ppb) - Xylenes 730 ppb - Ethylbenzene 350 ppb The groundwater in MW-3 is at 8.39 feet below around surface and the soil samples are located less than 5 feet from the groundwater. Due to the shallow groundwater, Category.3 of the Leaking Underground Fuel Tank(LUFT)Field Manual would typically apply. Clayton will consult with the Sa:t.Joaquin County, Environmental Health Division, and with the Central Valley Regional Water Quality Control Board(RWQCB) on the status of this site. • The concentration of hydrocarbon oil and grease was 250 parts per million (PPM) in a soff sample from MW-3. There are no set action levels for oil and grease; V however,when concentrations exceed 100 ppm the RWQCB's Recommendations for the Evaluation and Investipdon of USTs requires a soil/groundwater investigation. This study satisfies the RWQCB requirements. The 100 ppm level is not a cleanup level- The cleanuplevel is determined by assessing-the potential for soil contamination to impact grundwater. Hydrocarbon oil and.greasewere also detected in soil samples from.MW-1 and MW-2,but are within acceptable leve'ts as determined by the RWQCB. Clayton speculates that the ot7 and grease found in MW-1 and MW-2 may have come from oil-based sprays applied to the site for agricultural purposes. m.' • . Low levels of gasoline and the volatile Hydrocarbons ethylbenzene and xylene were found in the water sample',Ptrieved.from MW-3. These levels do not s exceed the California Department of Health Services (DHS)action levels. -iii-