SU0004912_SSNL - Laserfiche WebLink

Home Browse Search

FrDetention IME: = 1,200 gal tank capacityx 0 30%volume lost to sludge/scum accumulation) 2 (Peaking factor) x 180 gallon/day =2.3 days. The minimum acceptable detention time is 0.5 day. LEACHFIELDS Base Tank Capacity (BTC) +Average Daily Flow(ADF) x Soil Factor(SF) _ 1,200 gal BTC + 180 gal ADF x .250 SF = 345 lineal feet of leachline The Environmental Health Department will stipulate the actual lineal footage of leachline and the installation of seepage pits. Three -40 ft leachlines with 3 excavator-dug seepage pits at the ends of the leachlines may be installed. If there is expansion of the facility, or a need for additional effluent management, another 40 ft leachline and another excavator-dug seepage pit may be installed. Based upon the soil characteristics observed,the leachlines trenches will extend to the bottom of the black clay layer and into a compacted clayey silt. Several scientific studies have demonstrated that the infiltration capacity of a soil absorption system is dependant primarily by the formation of the biomat and not by the permeability of the soil. The biomat is a biological, slimy substance which forms on the soil-effluent interface over time. Effluent hydraulic loading rates range from a conservative estimate of 0.125 gal/ft2/day to 0.5 gal/ftZ/day. As a safety factor, these loading rates apply to trench side wall areas only. NITROGEN IMPACT MITIGATION Nitrogen mitigation can be primarily accomplished by the use of a dual compartment septic tank through the following processes: It has been well-documented that gaseous nitrogen emanates from septic tanks. The gaseous formation is apparently attributable to denitrification which is the biological reduction of nitrate (NO3) and nitrite (NO2)to volatile gases. The biochemical processes which occur in septic tanks are highly complex but can be described simplistically: A microbe digesting a waste organic molecule with an attached nitrogen atom may have the freed nitrogen as a surplus atom. To digest the N atom,the microbe can combine it with dissolved molecular oxygen OZ and release it in solution as a molecule of nitrite and possibly nitrate. This occurs under aerobic conditions and is referred to as nitrification. If a microbe needs oxygen within an anaerobic environment, it can take the oxygen from nitrite or nitrate molecules. Not requiring surplus nitrogen atoms, the microbe can combine pairs of surplus nitrogen atoms to form nitrogen gas (NZ). This is the denitrification process. Therefore,the first compartment of the septic tank should contain a higher concentration of oxygen from sink faucet aeration and the Lflushing action of toilets. This semi-aerobic environment may promote nitrification. As the L" is consumed in the first tank, effluent flowing into the second compartment should be predominately anaerobic. Under these conditions, denitrification should occur. 7 Vafley Ag Research