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Contribution of Rainfall <br /> An estimate of the quantity and quality of rainfall was required for the nitrate loading <br /> analysis. The Hantzsche and Finnemore method utilizes the "average recharge rate of <br /> rainfall' in calculating potential nitrate impacts to the aquifer. Not all rainfall will <br /> percolate into the aquifer; evapotranspiration, the sum of evaporation and plant <br /> transpiration, will reduce percolating effluent, especially in summer months. <br /> Rainfall recharge (deep percolation of rain) is a significant factor in the nitrate loading <br /> estimate; however, data on rainfall recharge rates are not widely available. For the <br /> Chico area, Hantzsche and Finnemore present an average rainfall of 22.5 inches per <br /> year and an estimated rainfall recharge of 16.8 inches per year; the recharge rate is <br /> calculated to be 75 percent of the average annual rainfall. Because the Chico area is <br /> similar geologically to San Joaquin County, for the purpose of this report Live Oak has <br /> selected 75 percent of average annual rainfall to represent the estimated rainfall <br /> recharge for the project area. Rodney Estrada of the San Joaquin County <br /> Environmental Health Department has confirmed that this approach should accurately <br /> characterize rainfall recharge in San Joaquin County (personal communication, January <br /> 6, 2017). <br /> Rainfall data for the north Stockton area was obtained from the Western Regional <br /> Climate Center. Stockton Fire Station 4 (045032), the closest active station to the Site, <br /> reports the average total annual precipitation from March 1906 through June 2016 to be <br /> • 15.37 inches. By assuming 75 percent of this precipitation percolates to the aquifer, the <br /> value of 11.5 inches average recharge of rainfall is obtained. <br /> The nitrate concentration of rainfall was estimated to be 1 mg/L-N (Hantzsche and <br /> Finnemore). <br /> Quantity and Quality of Domestic Wastewater <br /> Mr. Medina proposes to construct a four-bedroom home on the Site. The Site is <br /> currently orchard. <br /> Crites and Tchobanoglous (1998) list a typical flow rate of 50 to 70 gallons per person <br /> per day for an individual residence. The San Joaquin County Enviromental Health <br /> Department has indicated that maximum flow and double occupancy within each <br /> bedroom should be considered for the nitrate loading assessment; as a result, a value <br /> of 140 gallons per bedroom per day has been selected (personal communication, <br /> January 6, 2017). <br /> • LOGE 1902 Page 6 <br />