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Sources of Nitrate <br /> Septic systems and dairies have been found to be the most significant sources of nitrate <br /> in ground water. Orchards that require fertilization in sandy soils are also a significant <br /> source of nitrate contamination in shallow or sandy aquifers in San Joaquin County. <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 NortlJ. Stockton ea was obtained from the Western Regional <br /> Climate Center. The E64a tation (04503 ), the closest active station to the Site, reports <br /> the average total annual precipitation fr m January 1893 through January 2015 to be f <br /> 17.24 inches. By assuming 75 percent of this precipitation percolates to the aquifer, the <br /> value of 12.9 inches average recharge of rainfall is obtained. <br /> The nitrate concentratio -of rainfall was estimated to be 1 mg/L-N (Hantzsche and <br /> Finnemore) <br /> Quantity and Quality of Domestic Wastewater /�-- <br /> '101 <br /> Mr. Jhamat indicated that the proposed house will h ve five bedrooms. <br /> Crites and Tchobanoglous (1998) list a typical flow rate of 50 t6__7_0 gallons per person <br /> per day for an individual residence. The San Joaquin County Enviromental Health <br /> Depart has indicated that maximum flow and double occupancy within each <br /> bedr9ft should be considered for the nitrate loading assessment; as a result, a value <br /> of/ <br /> ,140 gallons per bedroom per day has been selected (personal communication, <br /> January 6(2017). <br /> LOGE 1847 Page 8 <br />