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im L March 24,2005 NOA Project Number: E05025A 4.0 GROUND WATER INFORMATION d 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. According to these maps (Plates 3-6),ground water lies between 20 and 30 feet below ground surface and flows at a gradient of about 5 feet per mile to the north in the vicinity of the Site. No ground water was encountered by the staff of Neil O.Anderson&Associates, Inc. during the drilling of the percolation test holes to a depth three feet on March 14,2005. 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. Any past agricultural activities and the present use of septic systems in the area should be considered potential ground-water contamination sources. 4.3 Water Sample Location r. One well permit was found for the subject property address of 13101 South Highway 99 Frontage, during file review at EHD on January 28,2005. This permit,dated June 24, 1986,was for the installation of a new domestic well. Two water samples were taken on March 16,2005 from the pipe manifold near the well for the wells located at both houses 13101 West Frontage Road and 13039 West Frontage Road.The locations of the samples are depicted on Plate 1. 4.4 Water Sample Constituents The water sample was analyzed for nitrate and DBCP. The results for Parcel 1(Northern house) are as follows: nitrate was found at 8.46 mg/L-NO3i below the maximum contaminant level (MCL) set by the US EPA of 45 mg/L-NO3. DBCP was not detected in the water sample. The results for Parcel 2 (Southern house) are as follows: nitrate was found at 37.3 mg/L-NO3,below the maximum G 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. V 5 '004 L