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I TABLE 3 IrI WELL WATER ANALYSIS: ,, WELL ANALYTE CONCENTRATION MAXIMUM CONTAMINANT FQLA'i� LEVEL(MCL) On-Site Nitrate 16 ppm 45 ppm Domestic Well (As Nitrate) Sampled from Sampling Port Dibromochloropropane Below Detectable Li its 0.2IL b on well DBCP (BDL) µ (ppb) discharge pipe. Calculation of Alkalinity Requirement for Nitrification The nitrate-nitrogen loading calculations are contingent upon the environmental factors required for nitrification to occur. These conditions include soil pare-space'oxygen content, soil temperature, pH, electrical conductivity, organic matter, cation exchange capacity, and alkalinity. Alkalinity in wastewater effluent is derived from the on-site well water that will be provided, in addition to the introduction of wastes to the effluent. Nitrification consumes approximately 7.1 mg of alkalinity for every mg of ammonia-nitrogen (NH4-N) oxidized. Nitrification of the average Total Nitrogen (TN) I4 concentration of 60 mg/L, as determined on Page 8, would require: 60 mg/L NH4-N x 7.1 mg CaCO3 =426 mg/L alkalinity. The alkalinity in the groundwater serving domestic water supplies in the Stockton locale are never this high. This low alkalinity concentration in the underlying groundwater supplies a indeterminable amount of insufficient alkalinity for nitrification to readily proceed. E. SURFACE WATER INFORMATION Storm water management must be by on-site retention basin until if, and when, public services are provided. Percolating rainwater from this structure may theoretically provide a water table dilution effect to percolating wastewater effluent depending upon the siting of each structure (basin and leachfield). Dilution effects can only be truly discerned with extensive groundwater monitoring and modeling. According to a scientific paper authored by Shaw and Turyk(1994), reduction of nitrate concentrations in groundwater can occur primarily through dispersion, by percolating rainwater, or a cleaner water source including effluent water recharge. Climatic Data: Rainfall versus Evapotranspiration NLS§3.2. It is generally and scientifically accepted that when precipitation exceeds evapotranspiration (Eta), deep percolation of surface rainwater may occur. Evapotranspiration refers to water evaporation that takes place both at the soil surface and transpiration by plants. k The following Table illustrates rainfall and evapotranspiration for the Stockton area. Precipitation data was obtained from the Soil Survey of San_Joa.quin Count' The conservative "2 years in 10" data was used and not the "average rainfall" data. Evapotranspiration data was obtained from the California Irrigation Management Information System (CIMIS)4: 6 1 t __j Chesney Consulting