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Blackwater and graywater will then gravity flow into a 1,200 gallon,two compartment, monolithic septic tank. The tank will trap paper, solids, etc and provide preliminary treatment. Effluent will then gravity flow approximately 77 ft, partially under the entrance driveway,to a distribution box (D-Box)to be equally divided between two 60 ft long Infiltrator Chamber® leachlines. At the ends of each chambered leachline will he a 48 dia., 25 ft deep seepage pit. Given the known hardpan soils at leachline depth, the seepage pits may ultimately manage most of the effluent. B. Domestic Wastewater Disposal System Design Specifications Wastewater Flow Volumes and Characteristics Since there are to be no food preparation or kitchen areas within the proposed facility, organic loading to the soil should be less than what would be observed in household domestic wastewater. It is imperative that no chemicals, solvents or petroleum products, other than low concentrations of household cleaners be introduced into the septic system. Regarding effluent flow volumes: Considering that if the toilet (1.5 gallon/flush)were flushed every one-half hour over an eight-hour work day, with a minimal sink water usage of 0.5 gals, we have 2 flushes/hr(1.5 gals/flush+0.5 gals for hand washing=2 gals) x 8 hrs = 32 gallons Average Daily Flow. This is a plausible ADF water usage. Septic Tank The septic tank will not have to be traffic rated since no vehicles will be traveling or parking over it. However, if there is a possibility of accidental vehicular traffic over the tank, crash posts shall be installed around the tank. Plans and specifications for the septic tank are found in Appendix B of this report. An effluent filter shall be installed in the second compartment of the tank. Peaking factors, used in the calculation below, 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 Calculation Detention Time= 1200ag I septic tank capacity x 0.70 (30% volume lost to sludge/scum accumulation) 2.5 (Peaking Factor) x 32 gals/day ADF Detention Time = 10.5 days. The minimum acceptable detention time is 1.0 days. Page -3- Chesney Consulting