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January 3, 2006 <br /> NOA Project Number: E05164A <br /> Table 3. <br /> Summa of Nitrate Mass Balance Analysis. <br /> Result Acres Average Daily Effluent Concen- Leachlield Deep Percolation of <br /> (Nc)* (A) Flow(Q) (Table 1) tration(Nw) Denitrifi- Rainfall(R) <br /> (mg/L-N) (gpd) (mg/L-N) cation(d) (Plate 9) (in.) <br /> 10.6 2 428 60 15% 11.69 <br /> F1 * Maximum contaminant level(114CL) for nitrate in drinking water is 10 mg/L-N: <br /> 3.6 Impact of Nitrate Loading to Nearby Water Sources <br /> The result of the nitrate loading balance indicates that the proposed use could potentially cause a <br /> buildup of nitrate in ihe'ground water above.10 mg/L-N over the long term. According to the <br /> F-I <br /> Hantzsche and Fennemore equation and approach, there is a potential for a buildup of nitrates in <br /> the ground water to-10.6 mg/L= <br /> DISCUSSION OF NITRATE LOADING RESULTS <br /> 4.1 Total Nitrate Impact <br /> According to the Hantzsche and Fennemore equation and approach there is a potential for a <br /> buildup of nitrates in the ground water to 10.6 nig/L-N over the long term. The calculated Nc value <br /> of 10.6 mg/L-N is slightly higher than the safe drinking water standard. The nitrate test in the well <br /> wa er indicates that this area is superable to leaching of nitrogen into ground water. <br /> I�4.2 Methods of Mitigation <br /> To mitigate the percolating nitrate, some simple measures should be utilized to improve the <br /> retention time and digestion of.the waste water in the septic system. To accomplish this,we would <br /> recommend installing an oversized septic tank and utilize a modified filter bed septic system. The <br /> modified filter bed should contain approximately 4 inches of loose compost or peat to provide a <br /> carbon source and slow the percolation rate. We recommend the following septic system size based <br /> F1on the proposed use as follows: <br /> Calculation for Filter Bed Disposal Field <br /> (San Joaquin County Onsite Waste Water Disposal Standards,2003) <br /> 4 Soil Factor(SF):0.200 -Sand and/or Sandy Loam (EHD Onsite Waste Wlater Disosal Standards) <br /> Base Tank Capacity (BTC): 1,200 gallons(EHD Onsite Waste Water Disposal Standards) <br /> Average Daily Flow(ADF): Office workers 2—35 gpd/person, 200 customers—5Od/customer <br /> ADF• 1,070 gallons per day (number also includes float/peaking factors) <br /> Calculated Tank Capacity (CTC): Value is minimum septic tank volume <br /> Calculation.BTC+ADF= CTC <br /> 6 <br /> P <br /> Fi <br />