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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 septic system from the existing house is the main, current on-site source of nitrate. Two septic permits were identified for the Site from among the San Joaquin County Environmental Health Department permit files: • February 1983 permit for repair to existing septic system. A 1,200-gallon septic tank was installed. • November 1987 permit for repair to existing septic system. A 100-foot leach line was added to the system; the drawing implies that a 2-foot by 10-foot by 8-foot deep sump was added as well. Waste from the chicken houses on the Site may also be a current source of nitrate. At the time of the inspection, 100 to 200 chickens were present. Mr. Foster indicated, however, that he is in the process of removing all the chickens. They will be replaced with rabbits that will live in wood-bottomed pens; Mr. Foster stated that he plans to dispose of the rabbit droppings off-site (personal communication, February 25, 2018). • LOGE 1807 Page 6