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composed of urea, which the main compound of urine. Proteins and urea are split by a bacterial enzyme into ammonia and carbon dioxide. Ammonia combines with water to form ammonium ions which can then be bacterially oxidized to nitrate. This process is called nitrification. Septic tank effluent contains nitrogen in high concentrations (75-80%), primarily as ammonium (NH4). Total nitrogen concentrations in effluent vary from 25 mg/l to 100 mg/l, with the average range being 35 to 62 mg/l of N. A maximum daily wastewater flow of 60 gallons can be projected based upon the following calculation: 4 people X 5 gallons per restroom visit X 2 visits per work shift X 50% safety factor=60 gallons. Therefore, 60 gals X 3.79=227.4 liters of wastewater X 62 mg/1= 14 g N/day X 300 days/yr= 42 kg N/yr or 92 lbs N/yr. This total nitrogen amount may be considered less than or comparable to,the amount of nitrogen applied to particular crops. [5] LOCAL GROUNDWATER INFORMATION The 1993 "Lines of Equal Depth of Water in Wells" map produced by the San Joaquin County Flood Control and Water Conservation District indicates that the static water level is located at approximately 12 feet below grade in the area of the subject site. Therefore, a five foot minimum distance between the bottom of a sump or leachline trench and the highest anticipated depth to " groundwater must be maintained. From several studies performed in the area, the groundwater flow appears to be in several different directions, although it may be considered to flow predominately toward the San Joaquin River, or to the west. [6] SOIL PROFILE AND PERCOLATION TESTING The percolation tests were performed according to the San Joaquin Environmental Health Department regulations. The perc test boring was performed in the leachfield area as indicated on the project blueprints. During the drilling procedures, a sandy silts, silty sands formation was encountered in the shallow test boring to a depth of 42 inches. This type of soil structure produces rapid percolation rates for sewage effluent. The perc test results are attached and illustrate a rapid perc rate of 7.5 minutes/inch. 1 Quality (�O.&.l I"PKti°n !