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The following day, the samples were transported to A& L Western Agricultural Labs in Modesto, (i f•�> under the attached Chain of Custody found in Appendix G. The constituents tested were for nitrate and Dibromochloropropane (DBCP),with the test results illustrated below: TABLE 4 WELL WATER ANALYSIS WELL ANALYTE CONCENTRATION MAXIMUM CONTAMINANT On-Site Nitrate 4 pp 45 ppm Domestic Well (As Nitrate) Sampled from — Hose Bibb, Dibromochloropropane Belo etectable Limits 0.2 /L b South of DBCP (BDL) Ft (ppb) House. Calculation of Alkalinity Requirement for Nitrification The nitrate-nitrogen loading estimation on Page 10 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 anticipated well water supply 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 82 mg/L, as determined at the bottom of Page 9 would require: 82 mg/L NH4-N x 7.1 mg CaCO, =582 mg/L alkalinity. The alkalinity in the well water is presently 125 ppm, so •� sufficient alkalinity does not exist which may theoretically retard nitrification to an indeterminable degree. This may also be contributing to the low nitrate concentration in the well water. E. SURFACE WATER INFORMATION Storm water management is proposed to be an on-site retention basin located in the northeast corner(NEC) of the subject property. There should be no impact to percolating septic effluent from the retention basin. In fact,the retention basin is theoretically down gradient to the future wastewater disposal area, since the groundwater directional flow is in an easterly direction. Percolating rainwater from this basin into the top aquifer mixing layer may create a dilution effect of the percolating septic system effluent. Groundwater dilution effects can only be truly discerned with 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, or by percolating rainwater recharge. 6