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IV. O.W.T.S. OPERATIONAL PARAMETERS AND COMPONENTS A. PROPOSED SEPTIC SYSTEM OPERATION SSS§ 3.7. The design of this conventional leachline disposal system is based upon the factors for efficient operation, disposal field longevity, and environmental protection. An overview of the system operation to serve the existing facility is as follows: Influent from the modular restroom will gravity flow to a 2,000 gallon standard precast concrete septic tank. Effluent from the second compartment of the tank will gravity to a distribution box (D- box) where effluent will be equally distributed between three 4" perforated drain pipe. The pipe is to be laid level with capped ends to promote equal distribution over the soil-effluent interface. A minimum of 18" of drain rock is to be placed under the drain pipe and 2" of rock above the pipe. Filter fabric is to be installed over the drain rock and backfilled to final grade with onsite native soil. The leachfield is to be constructed in the southeast corner of the property, as noted on the OWTS Site Plans found in Appendix B. The 100%reserve replacement area is denoted on the Site Plans and is directly adjacent to the north of the primary leachfield. B. SEPTIC TANK Septic tanks store accumulated sludge, scum and effluent(clear zone) volumes, which in turn affect treatment of nitrogen within the tanks. The calculations below demonstrate that the tank can easily maintain ample hydraulic residence time (HRT)of the influent for advanced treatment, particularly nitrogen: Detention/Hydraulic Residence Time Calculation: HRT Time=2000 gal tank capacity x 0.70(30%volume lost to sludge/scum accumulation) 1.5 (Peaking Factor)x 92 gals/day(ADF) Detention Time= 10 days. The minimum acceptable detention time is 1.0 day. C. LEACHLINE SIZING CALCULATIONS Base Tank Capacity(BTC)= 1,200 gal. Leachline Equivalent Requirement= 1,200 gallons BTC +92 ADF x 0.200 Soil Factor(SF)=258 lineal feet of leachline (LFLL) required. Install - 85 ft LL: 3 LL x 85 ft Long=255 LFLL Page -8- Chesney Consulting