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4,. United Parcel Service March 16, 1992 Page 2 Relevant background details regarding the waste oil excavation and stockpile are described below. The general site location is shown on the attached Plate 1, Vicinity Map. The location of the excavation is shown with respect to the building corner on Plate 2, Plot Plan. Our Site Safety Plan is appended. BACKGROUND INFORMATION e WASTE OIL EXCAVATION The existing excavation is roughly parallel with the southerly building wall near the southwest building corner. Upon removal of the tank, we understand the excavation i dimensions were about 5.5 by 11 by 10 feet deep. During our site visit, the extreme northerly limit of the excavation was within 5.5 feet of the building line at its nearest point and was filled with soft and saturated soil to within 4.5 feet of the adjacent paved surface. � E Following the tank removal, we understand that one soil sample was obtained from below the bottom of the excavation at a depth of about 12 feet. The sample was subsequently analyzed for BTEX, TPH as both diesel and motor oil, priority pollutant volatile organics and semi-volatile organics, the CAM-17 list of metals and hexavalent chromium. Only slight levels of toluene, xylenes, and various metals were detected. Toluene and xylene concentrations were .027 and .0067 parts-per-million (ppm), respectively. The detected metal concentrations are generally within expected background levels, although the concentrations of barium, copper, nickel and vanadium are equal to or exceed the California Code of Regulations, Title 22 Soluble Threshold Limit Concentrations (STLCs). ' Based on the described data, SJCEHD has required that additional excavation, sampling and testing be performed to confirm "clean" limits. SJCEHD has required that the soil samples be obtained from the approximate center of the excavation below the bottom and from the middle of each sidewall at the bottom. The samples must be analyzed for the above described compounds, as well as TPH as gasoline. SOIL STOCKPILE The soil removed from both the waste oil tank and gasoline tank excavations is covered with Visqueen and located on asphalt pavement at the southeast corner of the facility. Based on excavation and over-excavation dimensions presented in the f referenced Groundwater Technology report, it appears that the stockpiled soil includes about 240 cubic yards of soil removed from the gasoline tank excavation and only about 20 cubic yards from the waste oil tank excavation. Soil from the two sources appear to have been kept separate. The gas tank excavation soils appear to consist ■ Geotechnical ' : cc r