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First ground water is predicted at 80 feet below ground surface for this Site; <br />consequently, significant nitrate reduction would be anticipated as the septic effluent <br />percolates downward. <br />Sources of Nitrate <br />Dairies, orchards that require fertilization in sandy soils, and septic systems have been <br />found to be the most significant sources of nitrate in ground water. <br />Percolating Recharge Waters <br />Background <br />One of the most determinant factors in the Hantzsche and Finnemore equation is the <br />rate of recharge from percolating waters, which mix with the downward-percolating <br />effluent generated by on-site septic systems. In the original Hantzsche and Finnemore <br />paper, only "average recharge rate of rainfall" was considered. For the Chico area, <br />Hantzsche and Finnemore present an average rainfall of 22.5 inches per year and an <br />estimated recharge of 16.8 inches per year; the recharge value is 75 percent of the <br />average rainfall. <br />Methods in use in San Joaquin County <br />Within San Joaquin County, four methods have been identified to derive a value for the <br />rate of recharge from percolating waters: <br />100 Percent of Rainfall: This method involves identifying rainfall levels from the <br />closest data station to the project site, and assuming that 100 percent of rainfall <br />deep-percolates to the first saturated zone. This method likely over-estimates the <br />rate of recharge from percolating waters. <br />Rainfall data for the Acannpo area was obtained from the Western Regional <br />Climate Center (WRCC). The Site is located virtually equidistant from the Elliott <br />and Lodi stations. Rainfall data from these stations is presented, and an average <br />is calculated, in the following table: <br />LOGE 1906 Page 9