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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). The first hypothetical house on each parcel will have five bedrooms, which would result in a flow value of 300 gpd using the new method. The second hypothetical house will have three bedrooms, which would result in a flow value of 200 gpd. The maximum daily flow for each parcel is thus estimated to be 500 gpd. A typical residential concentration of 35 mg/L of nitrate as N was selected for the proposed residences (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 tend to denitrify at a lower rate of about 10 percent. A denitrification factor of 35 percent was selected for Parcels 1, 3, 4, 5, and 8 of the Site because of the clayey soil present at the percolation test locations. A standard denitrification factor of 25 percent was selected for Parcels 2, 6, and 7 of the Site because of the sand/silt mixtures present at the percolation test locations. Nitrate Loading Estimate Two nitrate loading scenarios were employed for each proposed parcel to determine the impact from the project to ground water: one scenario assuming no future development, and one scenario assuming the hypothetical future homes discussed above. The scenarios utilize the variables discussed previously, which represent the estimated conditions and uses associated with this project. The nitrate loading calculations are presented in Plates 23 through 30. LOGE 20-29 Page 13