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• The additional, future on-site source of nitrate will be the new septic system for the proposed house. No contribution from any irrigation or soil amendment is considered for the Hantzsche/Finnemore method. It is reasonably assumed that any irrigation or soil amendments would be applied at close to agronomic rates for a net balance of plant irrigation and nutrients. Contribution of Rainfall An estimate of the quantity and quality of rainfall was required for the nitrate loading analysis. The Hantzsche and Finnemore method utilizes the "average recharge rate of rainfall' in calculating potential nitrate impacts to the aquifer. Not all rainfall will percolate into the aquifer; evapotranspiration, the sum of evaporation and plant transpiration, will reduce percolating effluent, especially in summer months. Rainfall recharge (deep percolation of rain) is a significant factor in the nitrate loading estimate; however, data on rainfall recharge rates are not widely available. For the Chico area, Hantzsche and Finnemore present an average rainfall of 22.5 inches per year and an estimated rainfall recharge of 16.8 inches per year; the recharge rate is calculated to be 75 percent of the average rainfall. Because the Chico area is similar geologically to San Joaquin County, for the purpose of this report Live Oak has selected 75 percent of rainfall to represent the estimated rainfall recharge for the project area. • Rainfall data for the Escalon area was obtained from the Western Regional Climate Center. The Modesto City County Airport (045738), the closest active station to the Site, reports the average total annual precipitation from March of 1906 through June of 2016 to be 12.21 inches. By assuming 75 percent of this precipitation percolates to the aquifer, the value of 9.16 inches average recharge of rainfall is obtained. The nitrate concentration of rainfall was estimated to be 1 mg/L-N (Hantzsche and Finnemore). Quantity and Qualitv of Domestic Wastewater Mr. Foster proposes to place a three-bedroom mobile home on the Site. A two- bedroom house is currently located on the Site. 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). • LOGE 1807 Page 7