Laserfiche WebLink
Values and Assumptions: <br />1= 0.314 ac-ft <br />Nw = 62 mg N/L <br />d = Assume 20% due to the percentage of clay soil (-17%) throughout the soil profile that apparently shows <br />significant denitrification promoted by OM content of the surface soils. <br />R = 0.169 ac-ft <br />N b = Assumed to be 0.1 ppm NO3-N <br />0.314 ac-ft (62 mg N/L) (1 - 0.20) + (0.169 ac-ft x 0.1 mg/L) <br />Nr = (0.314 ac-ft + 0.169 ac-ft) <br />Nr = 32.3 ppm as nitrate-nitrogen (NO3-N) <br />IV. SEPTIC SYSTEM: COMPONENTS AND OPERATIONAL PARAMETERS <br />A. SEPTIC TANK <br />Septic tanks store accumulated sludge, scum and effluent (clear zone) volumes, which in turn affect <br />treatment of nitrogen within the tanks. Detention time calculations demonstrate that when the <br />maximum ADF is applied to the existing tank, there remains ample detention time: <br />Detention Time Calculation: <br />Detention Time = 1,200 gal tank capacity x 0.70 (30% volume lost to sludge/scum accumulation) <br />1.5 (Peaking Factor) x 280 gals/day (ADF) <br />Detention Time = 2.0 days. The minimum acceptable detention time is 1.0 day. <br />FILTER BED SIZING CALCULATIONS <br />The filter bed sizing per Section 9.8.1 of SJC OWTS Standards: 2 bedrooms = 160 LFLL <br />160 LFLL x 3 (sandy soils) = 480 sf. Proposed: Two filter beds, each 7' x 37' = 259 sf x 2 beds = 518 sf. <br />100% REPLACEMENT/RESERVE AREA <br />The 100% replacement area is denoted on the Plans and is to be located adjacent to Ash Street at the <br />front of the house. Total replacement area = 484 sf. When the primary disposal field fails, an <br />Orenco® Biotube must be installed in the second chamber of the septic tank with a duplex pump <br />system to pump effluent to the replacement area. <br />Page -6- <br />Chesney Consulting