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D. GROUNDWATER INFORMATION NLS ' SSS Groundwater depths and elevations throughout San Joaquin County are illustIJ d on maps published by the County Flood Control and Water Conservation District. The 2015 Lines of Equal Depth Maps and the Lines of Equal Elevation Maps indicate depth and directional flow in this specific location. Water table depth is approximately 55 ft below grade. Groundwater directional flow is in a northeasterly direction. NLS 1 ,3.1, SSS§J�1. Properties to the north, south, and west are currently commercial, Indus al and residential.((Considering that this area was farmed for decades,there may be a potential for nitrate contamination. NLS§ 2.3, SSS 3,4.4„4.5, 4.¢. The on-site domestic well is currently non-operatiohal a to a lack of electrics ;nd severe`vandalism. The well wi pled f the EHD requir ems of nitrate and DBCP concentrations when it beco operation 1, which is errkno at this time. An addendum to this report will be submitted to E when well water is sampled and tested. Calculation of Alkalinity Requirement for Nitrification The nitrate-nitrogen loading calculation results are contingent upon the environmental factors required for nitrification to occur. These conditions include soil pore-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, in addition to the introduction of wastes in 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) concentration of 62 mg/L, as determined on Page 7, would require: 62 mg/L NH4-N x 7.1 mg CaCO3 =440 mg/L alkalinity. The alkalinity in groundwater in this locale is always significantly lower than 440 ppm. Therefore, soil alkalinity and wastes will be providing the alkalinity source for nitrification, which can be considered minimal alkalinity. E. SURFACE WATER INFORMATION Storm water management will be by on-site retention. Percolating rainwater from the retention basin and percolating wastewater effluent may theoretically provide a water table dilution effect in the winter months to the nitrate concentration as accounted for in the nitrate loading calculations. A scientific paper authored by Shaw and Turyk (1994) found that 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 (Eto), deep percolation of surface rainwater may occur. Evapotranspiration refers to water evaporation that takes place both at the soil surface and transpiration by plants. 4