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TABLE 6 <br /> UNDERLYING GROUNDWATER ANALYSIS <br /> OF MAJOR CONSTITUENTS <br /> ANALYTE LEVEL FOUND MAXIMUM CONTAMINANT LEVEL(MCL) <br /> Nitrate 35.1 mg/L 45 mg/L(ppm) <br /> DBCP ND 0.2 µ/L(ppb) <br /> Total Dissolved Solids 830 mg/L 1,000 mg/L <br /> Specific Conductance 1,240 µmohs/cm 1,600 µmohs/cm <br /> pH 7.7 Range 6.5-8.5 <br /> Total Alkalinity 220 mg/L No Standard <br /> Arsenic 11 µ/L (FAIL) 10µ/L <br /> Manganese ND 50 µ/L <br /> Iron 50 300 µ/L <br /> The following is a brief summary of the test results: Arsenic was the only constituent tested that <br /> exceeded its MCL. The nitrate concentration exceeds one-half of the MCL Drinking Water <br /> Standard(which is 22.5 mg/L)by 13 mg/L(35 -22.5 = 12.5 mg/L). Under EHD guidelines, a <br /> public well that has a constituent over one-half of an MCL must undergo periodic monitoring. <br /> This may be monthly or quarterly monitoring. Dibromochloropropane (DBCP) was found to be <br /> 1 non-detect (ND). Total Dissolved Solids is at a concentration that is comparatively low for this <br /> locale. Total alkalinity plays a significant role in nitrate formation and a concentration of 220 <br /> mg/L can be considered low-to-medium for groundwater. It is normally the domestic water <br /> 1, supply and the alkalinity in the wastewater effluent that determines nitrification potential. <br /> i <br /> i <br /> SURFACE WATER <br /> 3.4 Climatic Data: Rainfall versus Evapotranspiration <br /> NLS§ 3.2 It is generally and scientifically accepted that when precipitation exceeds evapotrans- <br /> piration(Eto), deep percolation of surface rainwater may occur. Evapotranspiration refers to <br /> water evaporation that takes place both at the soil surface and transpiration by plants, and is <br /> defined as water loss from a large field of 4-to-7 inch tall, cool-season grass that is not water <br /> stressed. <br /> The following chart illustrates rainfall and evapotranspiration for the Stockton area. Precipitation <br /> data was obtained from the Soil Survey of San Joaquin County. The conservative "2 years in 10" <br /> data was used and not the "average rainfall" data. Evapotranspiration data was obtained from the <br /> California Irrigation Management Information System (CIMIS): <br /> Page -14- <br /> Chesney Consulting <br />