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Dr. Stuart Oakley of Chico State University states that"approximately 20%of the total nitrogen generated is removed in the septic tank." Thirdly, assigning a wastewater flow of 150 gals/day for each toilet, which is based on older style toilets, incorporates a large safety factor. IV. WASTEWATER DISPOSAL SYSTEM OPERATIONAL PARAMETERS Septic Tank Sizing Influent from the Men's/Women's Restrooms gravity flows into a 1,200 gallon septic tank. The tank must be pumped on a prescribed interval basis depending on direct observations of paper and scum accumulation; e.g., every six months to every three years, depending on sludge/scum accumulation to be determined from a septic system contractor. Peaking factors for septic tanks vary with usage during the hour of the day, and day of the week. Peak hourly rates are associated with normal working hours. The ratio of the peak day to the average day can vary from 1.5 to>5, depending upon the usage. A peaking factor of 2.5 (average between 0 and 5)will be used in the calculation below: Septic Tank Hydraulic Detention Time for the Septic Tank Detention Time= 1,200 gal septic tank capacity x 0.70(30%volume lost to sludge/scum accumulation) 2.5 (Peaking Factor)x 300 gals/day ADF Detention Time= 1.1 days. The minimum acceptable detention time is 1.0 days. Therefore, a 1,200 gallon septic tank is adequate. Primary and 100% Replacement Filter Bed Areas for the Men's and Women's Restroom The filter bed area is calculated in the procedure described in Section 8.7 of the San Joaquin County Sewage Standards and EHD Document 42-01-004 Calculation Requirements for Commercial Septic Systems: , Base Tank Capacity(BTC)= 1,200 gals Lineal Feet of Leachline (LFLL) = 1,200 BTC +300 ADF from both restrooms x 0.200 Soil Factor based on a sandy loam soil at 18 inches below grade where the soil-effluent interface will occur= 300 LFLL Filter Bed Area for the Restrooms=300 x 3 (Sandy Loam Soil Factor) = 900 square ft, or 30 ft square. The installed filter bed area, as illustrated on the Commercial Septic System Permit(See Appendix B), is 30 ft wide by 30.5 ft long. The 100%replacement area is denoted to be the same sized area. The filter bed area also corresponds with the percolation test results. As referenced above,the perc test results of 7.1 min/inch translate to an application rate 1.04 gals/ft'/day. Using the ADF of 300 gpd, we find: 300 gpd_ 1.04 gals/ft'/day =288 sq. ft. Therefore, the filter bed size of 900 ft' is exceedingly ample based on the test results obtained. The 100%replacement/reserve area is adequately situated adjacent to the north of the primary disposal areas. 9