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The maximum daily flow for the Site was estimated to be 700 gallons per day (gpd), 140 <br /> gallons per bedroom per day multiplied by five bedrooms. A typical residential <br /> concentration of 35 mg/L of nitrate as N was selected for the proposed residence (Crites <br /> and Tchobanoglous, 1998). <br /> The estimated flow values discussed here should not be used for the design and sizing <br /> of the septic system. The design and sizing of the septic system should utilize the San <br /> Joaquin County Environmental Health Department On-Site Wastewater Treatment <br /> Systems Standards which incorporate peak and surge flow factors. The estimates used <br /> in the On-Site Wastewater Treatment Systems Standards may be greater than those <br /> discussed here. <br /> No contributions from irrigation or soil amendments are considered for the <br /> Hantzsche/Finnemore method. It is reasonably assumed that any irrigation or soil <br /> amendments would be applied at close to agronomic rates for a net balance of plant <br /> irrigation and nutrients. <br /> Denitrification Reductions <br /> Denitrification is a process that occurs in the septic system drain field whereby certain <br /> bacteria oxidize the nitrate (NO3) in the wastewater and release nitrogen gas (N2) to the <br /> atmosphere. Due to the biologic processes in the shallow soils, nitrogen in the drain <br /> field will may undergo a reduction between 10 percent to 35 percent. Soils with higher <br /> clay content, moist soil conditions, high pH, and organic material denitrify by about 35 <br /> percent, and soils with high sand content and fast percolation rates tend to denitrify at a <br /> lower rate of about 10 percent. <br /> A denitrification factor of 25 percent was selected for the Site because of the clayey <br /> sand present at the percolation test location. <br /> Nitrate Loading Estimate <br /> A nitrate loading scenario was employed to determine the impact from the proposed <br /> project to ground water. The scenario utilizes the variables discussed previously, which <br /> represent the estimated conditions and uses associated with this project. The following <br /> table presents a summary of the assumptions for the nitrate loading calculation for the <br /> Site, as presented in Plate 10. <br /> LOGE 1847 Page 9 <br />