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a _ H y �F C 4 Clayton Clayton Environmental Consultants, Inc. was retained by Interland Corporation to 8upervi.e the excavation and aeration of petroleum hydrocarbon cantamirtated soil at 4715 1Ic st Grant Line Road in Traev, California. This project was authorized by Mr. Doh Lewis, Interland vice president, by accepting Clayton's Proposal No. 90-13- 1I.7, dated May 20, 1990, and a supplement Proposal No. 29531.00, dated August 20, 1990, with accompanying terms and conditions. Mr. Tom Ramsey of Fuel Oil Polishing was directly contracted by Interland to perform and backfilling. the soil excavation, aeration, '(OSHWork at the subject site begun in January 1990 when Orchard Supply Hardware ) retained Clayton to conduct a Phase I environmental assessment at the site. This assessment was performed to conduct a due diligence environmental investigation at the site prior to purchase by OSH. The Phase I assessment revealed that an underground storage tank (UST) which contained gasoline was operated onsite and was removed in 1986. Subsequently, OSH retained Clayton to install three monitoring wells to sample and analyze soil and groundwater at the site. Laboratory analysis of soil and groundwater detected gasoline and oil and grease contamination in soil samples. The maximum gasoline concentration found in the soil was 68 ppm and the maximum oil and grease concentration was 250 ppm. Groundwater samples from all three monitoring wells onsite did not indicate contamination of groundwater. De th to groundwater was measured to be between 8 and 10 feet. P Based on the analytical results, Clayton recommended excavating and aerating the soil in and around the location of the removed gasoline tank. Fuel Oil Polishing Company excavated about 1,650 cubic yards of soil fromthe vicinity of the UST. Th.s ;oil was stockpiled in thin layers on plastic sheeting for aeration. Soil samples were collected from the walls of the excavation pit to confi removal of contaminated soils. Analysis shorm satisfactory wed that concentrations of gasoline; benzene, toluene, ethylene, and xylenes (BTEX); and oil and grease in the sails were below those acceptable to the San Joaquin County Public Health Services, Environmental Health Division (PHS/EHD - the supe �iisory agency) in the final During excavation, a 500-gallon concrete septic tank was discovered. Clayton obtained a permit for the rernoval of this tank. The tank was removed on August 17, 1990. Analysis of soil samples Collected from beneath-the former location of the - - - removed septic tank did not reveal any significant contamination. After aeration of the excavated soil, eight composite samples were collected at the direction of PHS/EHD and analyzed for Total petroleum hydrocarbons (TPH) as gasoline, BTEX, and oil and grease. Laboratory analyses revealed the following: • Gasoline, benzene, crhylbenzene, and xylenes were not detected. Toluene was detected at concentrations of between 21 parts per billion b and 220 ppb. (PP ) -ii-