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June 13,2005 NOA Project Number: E05071A V4.0 GROUND WATER INFORMATION 4.1 Ground Water Depth and Gradient The San Joaquin County Flood Control and Water Conservation District (1998 and 1999) ground water depth and elevation maps were reviewed to determine the ground water levels near the Site. The Fall 1998 and Spring 1999 maps are the most current official maps available from the County. 6. According to these maps (Plates 3-6),ground water lies between 65 an feet below ground surface and flows at a gradient of about 5 to 8 feet per mile to the northeast in the vicinity of the Site. No ground water was encountered by the staff of Neil O.Anderson&Associates, Inc. during the drilling of two percolation test holes to a depth of 8 feet on June 8,2005. /4.2 Potential Ground Water Contamination Issues Identifying potential ground-water contamination sources was not part of the scope of work for the soil suitability study. Potential ground-water contamination can occur from a number of sources which often include leaky underground storage tanks, agricultural activities, dairies, septic systems, and storm water infiltration. Agricultural activities and the use of septic systems in the area should be considered potential ground-water contamination sources. /4.3 Water Sample Location No wells exist on the site. No well permits were found during file review at EHD on June 3,2005. �- A water sample was taken by Mr. Conor McGee of our office on June 5,2005 from the well head of Ron's Auto Service, the adjacent property to the south,which is owned by the subject property owner and located approximately 100 feet from the subject property itself. �� /�=� 41- V 4.4 Water Sample Constituents r. The water sample was analyzed for nitrate and DBCP. Nitrate was found at 21.1 mg/T.-Nn,_ helow the maximum contaminant level (MCL) set by the US EPA of 45 mg/L-NO3. DBCP was not detected in the water sample. The analytical reports prepared by Precision Enviro-Tech can be found in the appendix of this report. Well construction, seals,age and depth of the well screens may play significant part in assessing the 61. levels of Nitrate and DBCP in various aquifers. Without knowing specific details regarding well construction and condition,it would be difficult to accurately comment on the condition of the aquifer. Essentially, the water sample concentration approximately indicates the contaminant concentration level of the aquifer from which the well is drawing water. It is Neil O. Anderson and Associate's opinion that near surface aquifers are more likely to have elevated concentrations of Nitrate and DBCP than the deeper aquifers. However, the contaminant concentration in one aquifer 5