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The additional, future on-site source of nitrate will be the new septic system for the <br /> cottage. <br /> No contribution from any irrigation or soil amendment is considered for the <br /> Hantzsche/Finnemore method. It is reasonably assumed that any irrigation or soil <br /> amendments would be applied at close to agronomic rates for a net balance of plant <br /> irrigation and nutrients. <br /> 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 rainfall. Because the Chico area is similar <br /> geologically to San Joaquin County, for the purpose of this report Live Oak has selected <br /> 75 percent of rainfall to represent the estimated rainfall recharge for the project area. <br /> Rainfall data for the Tracy area was obtained from the Western Regional Climate <br /> Center. The Tracy Carbona station (048999), the closest active station to the Site, <br /> reports the average total annual precipitation from March 1906 through May of 2016 to <br /> be 9.86 inches. By assuming 75 percent of this precipitation percolates to the aquifer, <br /> the value of 7.4 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. Marrun is applying for approval of the two-bedroom cottage as legal living space. A <br /> three-bedroom home is currently located on the Site as well. <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 1840 Page 7 <br />