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V. CONCLUSIONS AND RECOMMENDATIONS SSS§5.4,6.8. The soils underlying the existing wastewater effluent disposal area show highly acceptable permeability at the soil-effluent interface representative of a filter bed. From the soil chemistry test results, it appears there is some denitrification potential from the soils, but not as significant as has been observed in other areas of San Joaquin County. NLS§ 4.2,SSS§ 6.7. Since the water table is relatively shallow in this locale at approximately 18 ft below grade, a filter bed disposal system allows the greatest distance between the soil-effluent interface and the depth to the water table. Consequently, a filter bed was the best option for the septic system structure to be installed for this project. By installing the filter bed as high in elevation as possible, evapotranspiration may be expedited,particularly depending if plants are grown over and near the disposal area. Downward migration of nitrate may be impeded. Additionally,the filter bed reduces the footprint of the disposal area in comparison to conventional leachlines. The filter bed sizing requirement calculations demonstrate the system has been installed with ample area as denoted on the commercial septic system permit for both the primary disposal and the 100%replacement areas. Railroad ties, or an equivalent barrier, shall be placed around the perimeter of the filter bed to prevent vehicles from driving or parking over it. NLS§ 4A. The nitrate loading calculations demonstrate that if the toilets in both the Men's and Women's Restrooms were flushed 200x per day(1.5 gals/flush x 200 flushes= 300 gpd ADF),the nitrate loading remains well below the Maximum Contaminant Level (MCL). It appears from the nitrate loading calculations, that nitrate loading potential could be significantly greater from the surrounding agricultural production land than from the disposal of on-site wastewater effluent. It is imperative that any food and food by-product wastes must be handled as solid wastes and not be disposed of into the septic system. This will prevent concentrated organic loading,prolong the lifespan of the wastewater disposal system and reduce nitrate loading potential. The fixtures in both restrooms should be checked periodically, preferably once per week to ensure there is no leakage that could cause failure of the disposal area. It is important to recognize that all septic systems have a lifespan, which is dependant on several factors and is therefore difficult to determine. Septic system failure would primarily result from the advanced formation of a "biomat" or "clogging mat" on the wetted soil/effluent interface. This mat is composed mostly of aerobic and anaerobic bacteria and bacterial products consisting of a slime of polysaccharides. Since the filter bed has been installed high in elevation,there will be a greater opportunity for oxygen intrusion from the atmosphere, thus theoretically assisting in biomat degradation, along with promoting evapotranspiration, as discussed above. 10