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D. G7, ssS§ UNDWATER INFORMATION NLS§ 2. 4.rGroundwater depths and elevations throughout San Joaquin County are illustrated on maps published by the County Flood Control and Water Conservation District. The Fall 2015 Lines of Equal Depth Map indicate the groundwater under the property to be approximately 65 feet below grade. This depth can be attributable to the past five years of drought and was verified by the static water level measurement in the new well drilled for the project. It is known that the water table has been much shallower in this locale; to depths of 10-15 ft below grade. The Fall 2016 Lines of Equal Elevation Map illustrates the groundwater directionalflow to be in a rtheasterly direction. J NLS§2.2 3.1, SSS§ 2.1, 4.2/Since the surrounding properties have been fanned for a number of decades, along with high density housing on septic systems directly upgradient to the project, the potential for nitrate contamination to the underlying groundwater aquifers can be considered significant. NLS§ 23, SSS§ 4.3, 4.4, 4.5, 4.6. There omestic wells on the subject Parcel. A south well was existing and has been refurbished.�Prtfew well to the north was drilled in April of this _ year. On May 4, 2017,this new well seas sampled�ror the EHD required constituents of DBCP and nitrate. The test result ere reported on May 23,2H7_with a result of BDL for DBCP and a nitrate concentrat n of 509 pp nitrate. Calculation of Alkalinity Requirement for Nitrification The nitrate-nitrogen loading to the underlying groundwater is 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. 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 6, would require: 62 mg/L NHa N x 7.1 mg CaCO3 =440 mg/L alkalinity. The alkalinity concentration in the groundwater in this locale ranges between 150 ppm and 250 ppm, certainly lower than 440 mg/L. Therefore,there is an insufficient alkalinity in the groundwater for complete nitrification to readily proceed without the introduction of wastes along with the alkalinity in the soil environment. E. SURFACE WATER INFORMATION Storm water drainage management will be by on-site retention located at the north end of the property. Percolating rainwater may theoretically provide an indeterminable water table dilution effect to percolating wastewater effluent since the disposal area is up gradient. However, as referenced in the next Section, rainfall in comparison to evapotranspiration is minimal. Page-4-