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nicm <br /> ENGINEERING <br /> MWOWMIXIMMUMMOO"I . 1 <br /> 1 . This flowrate is the max event time and therefore the max event <br /> flowrate that the building can contribute on a given day . <br /> ii . ADF = MDF * 15 Events/Year / 365 days/year = 25 gal/day <br /> c . System B ADF = 620 + 25 = +645 gal/day <br /> d. System B MDF = 620 + 600 = 1 ,220 gal/day <br /> Septic Tank <br /> The septic tank is calculated based on the ADF and the base tank capacity per SJC OWTS 4. 1 . 12 . If the ADF is <br /> below 1 ,500 gallons then the Calculated Tank Capacity (CTC) is the Base Tank Capacity (BTC) plus the ADF . If <br /> the ADF is above 1 ,500 gallons then the CTC is calculated by Equation 1 . <br /> Leach Field <br /> To calculate the required leach line length first the required percolation volume must be determined. The required <br /> percolation volume is calculated by adding the BTC and the ADF per SJC OWTS 9 .7 .2 . Instead of multiplying the <br /> " Soil Factor", per SJC OWTS , the required is calculated as follows . First calculate the Required Percolation Area, <br /> the Required Percolation Volume divided by the Applicable Percolation Rate . (See Equation 2). Next calculate the <br /> Design Percolation surface area per lineal foot of leach line, for a safety factor the design surface area only includes <br /> the bottom of the trench and the sidewalls below the invert of the perforated pipe . The required leach field length is <br /> then the Required Percolation Area divided by the Design Percolation Surface Area per Lineal Foot. (See Equation <br /> 3 ) . <br /> Example Leach Field Calculation (Leach Field A) <br /> 1 . MDF = 7,460 gal/day <br /> 2 . BTC = 1 ,200 gal/day <br /> 3 . VRequired = MDF + BTC = 7,460+ 1 ,200 = 8 ,660 gal/day <br /> 4 . ARequired = VRequired / P = 8 , 660 / 3 . 5 = 2,474 sf <br /> 5 . ADesign perft = Trench Bottom + 2 * (Trench Sidewall Below Pipe Invert) _ [24" + 2 * ( 12")] / 12" = 4 sf/ If <br /> 6 . LRequired = ARequired / ADesign per ft = 2474/ 4 = 619 ft <br /> Example Leach Field Calculation (Leach Field B) <br /> 7 . MDF = 1 ,220 gal/day <br /> 8 . BTC = 1 ,200 gal/day <br /> 9 . VRequired = MDF + BTC = 1 ,220 + 1 ,200 = 2,420 gal/day <br /> 10 . ARequired = VRequired / P = 2,420 / 3 . 5 = 691 sf <br /> 11 . ADesign per ft = Trench Bottom + 2 * (Trench Sidewall Below Pipe Invert) _ [24" + 2 * ( 12")] / 12" = 4 sf/lf <br /> 12 . LRequired = ARequired / ADesign per ft = 691 / 4 = 173 ft <br /> • • <br />