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Quantity and Quality of Domestic Wastewater Mr. Bavaro indicated that the existing house on Parcel 2 has three bedrooms. For the purpose of the nitrate loading calculation, a potential future second unit dwelling with three bedrooms is considered. Potential future three-bedroom primary and second unit dwellings on Parcel 1 are considered as well. No new construction is planned. Crites and Tchobanoglous (1998) list a typical flow rate of 50 to 70 gallons per person per day for an individual residence. The San Joaquin County Enviromental Health Department has indicated that maximum flow and double occupancy within each bedroom should be considered for the nitrate loading assessment; as a result, a value of 140 gallons per bedroom per day has been selected (personal communication, January 6, 2017). The maximum daily flow for the Site was estimated to be 1,680 gallons per day (gpd), calculated as 140 gallons per bedroom per day multiplied by 12 bedrooms. A typical residential concentration of 35 mg/L of nitrate as N was selected for the proposed residence (Crites and Tchobanoglous, 1998). The estimated flow values discussed here should not be used for the design and sizing of the septic system. The design and sizing of the septic system should utilize the San Joaquin County Environmental Health Department On-Site Wastewater Treatment Systems Standards which incorporate peak and surge flow factors. The estimates used in the On-Site Wastewater Treatment Systems Standards may be greater than those discussed here. Denitrification Reductions Denitrification is a process that occurs in the septic system drain field whereby certain bacteria oxidize the nitrate (NO3) in the wastewater and release nitrogen gas (N2) to the atmosphere. Due to the biologic processes in the shallow soils, nitrogen in the drain field may undergo a reduction between 10 percent to 35 percent. Soils with higher clay content, moist soil conditions, high pH, and organic material denitrify by about 35 percent, and soils with high sand content and fast percolation rates tend to denitrify at a lower rate of about 10 percent. A denitrification factor of 20 percent was selected for the Site because of the mixture of sand and silt present at the percolation test locations. Nitrate Loading Estimate A nitrate loading scenario was employed to determine the impact from the proposed project to ground water. The scenario utilizes the variables discussed previously, which represent the estimated conditions and uses associated with this project. The following LOGE 1907 Page 14