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Quantity and Quality of Domestic Wastewater Mr. Singh indicated that the proposed primary residence will have five bedrooms, and the proposed second unit dwelling will have one bedroom. Crites and Tchobanoglous (1998) list a typical flow rate of 50 to 70 gallons per person per day for an individual residence. In the past, San Joaquin County Environmental Health Department has requested that the flow rate be calculated as 140 gallons per bedroom per day to reflect maximum usage. On March 4, 2020, however, Michael Kith, Registered Environmental Health Specialist, Program Coordinator at the San Joaquin County Environmental Health Department, stated that he has conferred with Norman Hantzsche (author of the 1992 paper discussed previously), and they have arrived at a new method to determine flow from residential sources. He indicated that wastewater flow from a single-family residence should be calculated as 100 gallons per day (gpd) for the first bedroom and 50 gpd for each additional bedroom; additional residences should be calculated in the same manner (personal communication, March 4, 2020). Using this method, the primary residence contributes 300 gpd, and the second unit dwelling contributes 100 gpd, for a total maximum daily flow rate of 400 gpd. A typical residential concentration of 35 mg/L of nitrate as N was selected for the proposed residence (Crites and Tchobanoglous, 1998). 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 tend to denitrify at a lower rate of about 10 percent. A denitrification factor of 35 percent was selected for the Site because of the clayey soil present at the percolation test location. 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 table presents a summary of the assumptions for the nitrate loading calculation for the Site, as presented in Plate 15. LOGE 20-44 Page 10