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Fvc ASTEWATER DISPOSAL SYSTEM PERATIONAL PARAMETERS As referenced above,although numbers of on-site people have not been projected in the Application,the Average Daily Flow(ADF)for sizing criteria must be based on the premise,which is a law,of using low-flow toilets and can be independent of the flows for the nitrate loading calculations. Consequently,a total of 100 flushes/day will be assigned for all four toilets(25 flushes/toilet/day=3 flushes/hr/8 hr day)for a total of 100 flushes/day x 1.5 gals/flush= 150 gals ADF from both buildings. This incorporates a sizeable safety factor for the sizing of the filter bed. A filter bed disposal structure is proposed instead of conventional leachlines to reduce the disposal area footprint. Septic Tank Sizing Influent from the Office and Maintenance Buildings will gravity flow into 1,200 gallon septic tanks,one tank for each building. It is imperative that the influent lines are as high in elevation as possible so that the septic tank is also as high in elevation as possible. Then it can be assured that the effluent will gravity flow to the filter beds and not have to be pumped. 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 Each Septic Tank Detention Time= 1,200 pal septic tank capacity x 0.70(30%volume lost to sludge/scum accumulation) 2.5(Peaking Factor)x 75 gals/day ADF From EACH Building into EACH Tank Detention Time=4.5 days.The minimum acceptable detention time is 1.0 days. Therefore, 1,200 gallon septic tanks are adequate for each building. Primary and 100%Replacement kilter Bed Areas for Each Building The filter bed area is calculated in the procedure described in Section 8.7 of the San Joaquin County Sewagg S� ards and EHD Document 42-01-004 Calculation Recuirements for Commercial o ,,Systems: Base Tank Capacity(BTC)= 1,200 gals Lineal Feet of Leaohline(LFLL)= 1,200 BTC+75 ADF from each building x 0.225 Soil Factor based on a loam soil at 36 inches below grade where the soil-effluent interface is , *at cur=290 LFLL Filter Bed Area For Each Building=290 x 3(Sandy Loam soil FactorAZ 870 square ft, r 30 it square. The leachfield/filter bed areas, as illustrated on the Site Plans(See App sufficient area for both the primary disposal areas and the 100%replacement areas. Total area(including separation distances from each filter bed)must be 150 ft long x 30 ft wide=4,500 sq. ft. The filter bed area also corresponds with the percolation test results. As referenced above,the perc test results of 8.6 min/inch translate to an application rate of 0.857 gals/t{'/day. Using the ADF of 150 gpd,we find: 150 gpd=0.857 gals/ftr/day = 175 sq. ft. Therefore,the filter bed size of 870 sq. ft is ample based on the test results obtained. The 100%replacement/reserve area can be adequately situated adjacent to the primary disposal areas. 9 Chesney Consulting