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documentation to McCampbell Analytical, Inc. of Pittsburg, California. Laboratory analytical documentation is provided in Appendix D. One soil sample from each of the three boring (SB1 through SB3) and the single groundwater sample, which was collected from borings SB1, were selected for analyses (four total samples). Laboratory analysis of three soil samples consisted of the following: • TPH multi-range by EPA Method 8015B (with silica-gel cleanup for diesel and motor oil). • Volatile Organic Compounds by EPA Method 8260B. Laboratory analysis of the one groundwater sample consisted of the following: • TPH Multi-Range by EPA Method 8015B (with silica-gel cleanup for diesel and motor oil). • Volatile Organic Compounds by EPA Method 82608. 4.0 FINDINGS The results of this investigation were compared to the Environmental Screening Levels (ESLs) from the California Regional Water Quality Control Board. The ESLs are considered to be conservative. Under most circumstances, and within the limitations described, the presence of a chemical in soil, soil gas or groundwater at concentrations below the corresponding ESL can be assumed to not pose a significant, threat to human health and the environment. Additional evaluation will generally be necessary at sites where a chemical is present at concentrations above the corresponding ESL. GEOLOGY AND HYDROGEOLOGY Sediment encountered in each of the borings generally consisted of mostly clay and silt to the total depths explored. A layer of sand was noted in boring SB1 between 15 and 19 feet bgs and a layer of silty sand was noted in boring SB2 between 15 and 17 feet bgs. Groundwater was encountered in boring SB1 at a depth of 36 feet bgs. Groundwater was not encountered in borings SB2 and SB3. SOIL SAMPLE ANALYTICAL RESULTS The following information is a summary of the soil sample analytical test results. This information has also been included in Table 1. Total Petroleum Hydrocarbons as gasoline (TPHg • TPHg was not detected any of the borings above the laboratory detection limits. Total Petroleum Hydrocarbons as diesel (TPHd) • TPHd was detected in boring SB1 at 2.1 mg/kg, which does not exceed the ESLs. • TPHg was not detected in borings SB2 or SB3. Total Petroleum Hydrocarbons as motor oil (TPHmo) • TPHmo was not detected any of the borings above the laboratory detection limits. Project No. 305662 AE1 April 4, 2012 Page 4 of 6