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The calculated nitrate loading concentration in the recharge effluent from the entire new winery l i facility is calculated to be under the Maximum Contaminant Level limit for nitrate in drinking - water. The variables used in the calculations above are very conservative. For example, the use of 103 mg N/L, is a much higher nitrogen concentration than those concentrations typically found in domestic or residential sources. (rl { ) Secondly, various researchers place the nitrogen reduction occurring in septic tanks at 10% to 20%. From the May 8, 2003 Symposium "Onsite Wastewater Treatment - Nitrogen Removal," Dr. Stuart Oakley of Chico State University states that "approximately 20% of the total nitrogen generated is removed in the septic tank." As noted above, a conservative estimate of 10% was used for the existing 1,600 gallon septic tank. Thirdly, the biomat does have the beneficial property of removing approximately 10% of the nitrogen from disposal systems. This figure was not used in the nitrate loading calculations also to maintain a conservative loading concentration. C. SEPTIC SYSTEM OPERATIONAL PARAMETERS AND COMPONENTS SSS§ 3.7. Discussion of efficient operation, disposal field longevity, and environmental protection are based upon the environmental parameters discussed below. An overview of the system operation is as follows, and is based upon the schematic found in the EHD microfiche files. The exact structures of the existing septic system cannot be accurately discerned since they were not labeled in this schematic: Influent waste from the two winery restrooms and employee restroom w'I] gravity to the existing 1,600 gallon septic tank. Effluent from this tank will then gravity flow equally between one leachline and one seepage pit, and three existing and two new seepage pits. Effluent overflow from this one pit will be directed into two new pits which were installed in November 1990. As referenced, since saturated soils were observed the entire depth of 25 feet, EHD will require the installation of two additional pits, for a total of six seepage pits. SEPTIC TANK Septic tanks store the accumulated sludge, scum and effluent (clear zone) volumes, which in turn affect treatment of nitrogen within the tanks. In the following calculation, the pump-out interval factor times the QAVE times the peaking factor(PF) correlate the pump-out time interval in years with the recommended tank capacity. The peaking factor value for this project is estimated to be 1.5. It is known that the existing, original septic tank is 1,600 gallon capacity. Recommended tank capacity for a potential pump-out interval of three years after operation: 2.8(pump-out interval factor) (QIVE) x Peaking Factor(PF= 2.5) —2.8 (450 gpd) x 1.5 = 1,890 gals. Total septic tank capacity— 1,600 gallon tank. Therefore, the tank may have to be pumped sooner than three years. Detention Time: Detention Time= 1,600 gal total tank capacity x 0.70 30% volume lost to sludge/scum accumulation 1.5 (Peaking factor) x 450 gals/day (ADF) Detention Time= 1.7 days. The minimum acceptable detention time is 1.0 day. Therefore, the existing 1,600 gallon septic tank is suitable for sufficient detention time with an adequate safety factor. 9 Chesney Consulting