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January 16,2004 . <br /> Job Number:LG03-304 <br />[ Page 1`3 <br /> A`denitrification factor of25�ercent was selected for use which accounts for the fine grained <br /> soils encountered during the drilling of the percolation test. <br /> 7.4-Nitrate Loading Scenarios <br /> One nitrate loading scenario was perforated to determine the potential impact to ground water <br /> from-the use.of a septie.systems associated with the proposed project-. The nitrate loading <br /> calculation is.presented as Plate 5 in the appendix:. The following'table presents=a summaryof <br /> the nitrate loading results and variables used. <br /> Table 7., <br /> Summary of Nitrate Mass Balance Analysts. <br /> o Result Acres Average Effluent Leactsfiield Deep Percolation <br /> Calculatz n <br /> (Nc) * ' . (A) Daily Flow Concentration Denitrifi- of Rainfall(R) <br /> (Q)(Sec:3.6) (Nw) . cation(d) (Plate-4) <br /> see Plate 5 18.9m L-N V1 94 d", 35 pL-N 25% 1:07 inL <br /> *. Maximum ntarninate le 1(MCL)for at eking water is 10 mg/L N.Estimate does not.include nitrate <br /> contribution from ricul e or landscaping- <br /> Based-on the method.and assumptions described,the nitrate loading balance indicates the <br /> development will likely cause a build up of nitrate in ground water_ well above 10 mg/L-N for the <br /> Tong term: A standard type septic system a ears to be,unsuitable for waste water disposal on the <br /> Site: These of a properly designed engineered septic system.will lower e concentration of e <br /> waste water to a concentration of 10 mg/L-N or less. This level has been acceptable to the EHD <br /> on similar projects. <br /> 8.0 SUMMARY AND RECOMMENDATIONS <br /> A satisfactory percolation rate of 10 minutes per inch was-measured for the shallow percola�; <br /> test boring- The:depth to ground water below the Site was found to be at a dee t �f�et. The <br /> .1 San Joaquin County Health Department believes this level could fluctuate and potentially <br /> inundate a standard type leach line septic system. The EHD indicated osal <br /> field should be utilized in this area to m" '_ epotential shallow o_u_nd_water below to <br /> ,.septic system disposal field. <br /> A nitrate and DBCP. test from a neighboring water well indicated that no DBCP was detected in, <br /> the water sample: Nitrate was found at a concentration of 26.1 mg/L-N which is below.the <br /> x <br /> r <br />