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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 of the San Joaquin County Environmental Health Department dictated a new procedure for calculating residential flow, developed in consultation with Norman Hantzsche (author of the 1992 paper discussed previously). 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 existing five -bedroom home on Parcel 1 is calculated to yield a flow value of 300 gpd. The existing four-bedroom home on Parcel 3 is calculated to yield a flow value of 250 gpd. For the hypothetical future development on Parcel 2, the first house will have five bedrooms, which results in a flow value of 300 gpd. The second house will have three bedrooms, which results in a flow value of 200 gpd. The maximum daily flow for the parcel is thus estimated to be 500 gpd. No construction is anticipated. 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 incorporates 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 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 clay soil observed on Parcel 2 and noted throughout the Site by the Soil Survey. LOGE 2141 Page 12