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r. in. July 28, 2006 NOA Project Number: E06068A 4.0 GROUND WATER INFORMATION 41 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 70 and 80 feet below ground / surface and flows at a gradient of about 10 feet per mile to the northwest in the vicinity of the Site. v�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 Two wells exist on the site. One well permit was found for the installation of a domestic well on March 12, 1993.Accordinizto Dan Tabar and the domestic well installation permit, there is also an agricultural well on the sitA mestic well by Mr.Jessen Welch of our office on June 6,2006. �- 4.4 Water Sample Constituents The water sample was analyzed for nitrate and DBCP. Nitrate was found at 17.9 mg/L/L=NOS, below �. the maximum contaminant level (MCL) set by the US EPA of 45 mg/L-NO3. DBCP was found at .30 ug/L which is above the MCL set by the EPA of.20 ug/L. The analytical reports prepared by FGL Environmental can be found in the appendix of this report. The presence of nitrates is not uncommon in shallow ground water aquifers in San Joaquin County and other parts of the Central Valley. Nitrate in ground water occurs as a result of the application of fertilizers,livestock waste, and untreated septic tank waste. Nitrate is mobile and often accumulates in the shallow ground water zones. bin 5 6.