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Because the San Joaquin County Environmental Health Department has requested that local and recent data be utilized wherever possible, the concentration of the Lodi rainwater been selected for use in the nitrate loading calculation. Quantity and Quality of Domestic Wastewater According to Ms. Rosas, the proposed new home will be four to six bedrooms in size. 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, Lead Registered Environmental Health Specialist 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, a four-bedroom house would contribute 250 gpd, a five-bedroom house would contribute 300 gpd, and a six-bedroom house would contribute 350 gpd. 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's On-Site Wastewater Treatment Systems Standards (2017), 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. A typical residential concentration of 35 mg/L of nitrate as N was selected (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 waste water 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. The soil on the Site was found to be silty clay. A denitrification factor of 35 percent was selected for the Site because of the clay content of the shallow soil encountered. LOGE 20-21 Page 8