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NITRATE LOADING STUDY <br /> Because of statewide concerns of nitrate leaching into ground water from septic <br /> systems, a nitrate loading analysis was required by the San Joaquin County <br /> Environmental Health Department for approval of the proposed project. The study <br /> estimates the potential concentration of percolating effluent produced by the project <br /> over the long term. Where percolating effluent leaches into the ground, ground water <br /> quality may be impacted to some degree should the effluent reach ground water. <br /> The method utilized for the nitrate loading analysis is based on a simple and convenient <br /> mass balance formula, discussed in a published paper by Hantzsche and Finnemore <br /> (1992). <br /> Hantzsche and Finnemore have found from investigations conducted in the Chico, <br /> California area, the water quality in the upper saturated ground-water zone closely <br /> approximates the quality of percolating effluent from septic systems. They have <br /> developed a simple method that could be used to estimate the quality of the percolating <br /> effluent from septic systems. The quality of the percolating effluent may represent the <br /> potential worst-case condition the upper aquifer would ever experience from the use of <br /> on-site septic systems. Mixing and dilution in the aquifer as well as adsorption and <br /> adhesion in the soil would tend to substantially reduce the concentration of percolating <br /> effluent. <br /> The Hantzsche and Finnemore equation is a conservative approximation of ground- <br /> water nitrate-nitrogen concentration resulting from the combined effect of on-site <br /> sewage disposal systems and percolating recharge waters. The equation and method <br /> is for estimation of long-term effect ground-water quality, and is not intended for <br /> prediction of seasonal changes (Hantzsche and Finnemore, 1992). <br /> For the purpose of the Hantzsche and Finnemore equation, only septic effluent is <br /> included in the nitrate loading calculation; no other potential sources of nitrate are <br /> considered. <br /> The method takes into account the development area, soil denitrification factor, rate of <br /> recharge from percolating waters, waste effluent quantity, and waste effluent nitrate <br /> concentration from on-site septic systems, and predicts the nitrate concentration of <br /> percolating effluent. <br /> LOGE 2115 Page 8 <br />