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NITRATE LOADING STUDY The method utilized for the nitrate loading analysis is based on a simple and convenient mass balance formula, discussed in a published article by Hantzsche and Finnemore (1992). Hantzsche and Finnemore have found from investigations conducted in the Chico, California area, the water quality in the upper saturated ground-water zone closely approximates the quality of percolating effluent from septic systems. They have developed a simple method that could be used to estimate the quality of the percolating effluent from septic systems. The quality of the percolating effluent may represent the potential worst-case condition the upper aquifer would ever experience from the use of on-site septic systems. Mixing and dilution in the aquifer as well as adsorption and adhesion in the soil substantially reduce the concentration of percolating effluent. The Hantzsche and Finnemore equation is a conservative approximation of ground- water nitrate-nitrogen concentration resulting from the combined effect of on-site sewage disposal systems and precipitation of rain. The equation and method are for estimation of long-term effect ground-water quality, and are not intended for prediction of seasonal changes (Hantzsche and Finnemore, 1992). The method takes into account the development area, soil denitrification factor, rainfall recharge rate, rainfall nitrate concentration, waste effluent quantity, and waste effluent nitrate concentration from on-site septic systems. On-Site Sources of Nitrate The current on-site sources of nitrate are the two existing houses. Live Oak searched the septic system permits on file at the San Joaquin County Environmental Health Department; two permits were identified for the Site address: • July 1972 permit for new septic system at guest house. The system utilized a 1,200-gallon septic tank, a 100-foot leach line, and a 25-foot deep by 36-inch diameter seepage pit. • March 2001 permit for repair to residential septic system. The permit indicates that a 40-foot leach line and a 25-foot deep by 36-inch diameter seepage pit were added to the existing system. The septic permits have been included in Appendix 4 of this report. There are no additional future sources of nitrate. LOGE 1916 Page 6