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IV. WASTEWATER DISPOSAL SYSTEM OPERATIONAL PARAMETERS The new septic system for the Blue Rhino Office Trailer will be sized for 150 gpd under EHD Sewage Standards criteria. This Average Daily Flow (ADF) is based on the premise of one uni-sex restroom with one low-flow toilet. A filter bed disposal structure is proposed instead of conventional leachlines to reduce the disposal area footprint. Septic Tank Sizing Influent from the Office Trailer will gravity flow into a 1,200 gallon septic tank Effluent from this tank will gravity to the filter bed as illustrated on the Site Plans. 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. 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 Detention Time= 1,200 gal septic tank capacity x 0.70(30%volume lost to sludge/scum accumulation) 2.5 (Peaking Factor)x 150 gals/day ADF Detention Time=2.2 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 Area 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 + 150 ADF x 0.225 Soil Factor based on a loam soil at 40 inches below grade where the soil-effluent interface will occur= 304 LFLL Filter Bed Area=304 x 3 (Sandy Loam Soil Factor)=912 square feet. The primary filter bed area, as illustrated on the Siegfried Site Plans, is proposed to be rectangular in area: 35 ft wide E-W x 40 ft long N-S = 1,400 sq ft available for the primary filter bed area. The filter bed area also corresponds with the percolation test results. As referenced above, the application rate correlated with the perc test results of 8.9 min/inch translate to an application rate of 0.857 gals/ftt/day. Using the ADF of 150 gpd, we find: 150 gpd_ 0.857 gals/ft'/day = 175 sq. ft. Therefore, the filter bed size of 912 sq ft is adequate based on the test results obtained. The 100% replacement/reserve area is directly east of the primary filter bed area in the parking area, and also has 1,400 sq. ft. of available area. 10 Chesney Consulting