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F YSTEM OPERATIONAL PARAMETERS AND COMPONENTS - CHFIELD (E.L.F.) AREA TO SERVE THE NEW OFFICE BUILDING esign of the future pressurized filter bed disposal system for the facility are based pof efficient operation, disposal field longevity, and environmental protection. An overview of the system operation is as follows for the new Office Building: Influent waste from the building will gravity through a six-inch ABS tightline across the parking area for approx. 110 ft, into a single compartment 2,000 gal septic tank. The effluent will then gravity into a second, single compartment 2,000 gal tank. Lastly, the effluent will gravity into a third, two compartment 2,000 gal tank. The second compartment will be the pump chamber with a Biotube filter vault, duplex pump system to pressurize effluent, alternating between two filter bed cells, as depicted on the Site Plans. As referenced below, each filter bed cell is to be 10 ft wide, with the pressurized laterals situated 3.3 ft in from the edges of each bed. The filter beds and 100%reserve areas are to be installed in a proposed landscaped lawn area. It is our understanding this lawn area is to have gentle (2 ft height max) undulations which will cause the drain rock and laterals to "follow"these undulations. A hypothetical question arises regarding the potential of effluent percolating through the drain rock to "pool' at the lower elevations before percolating into the soil at the soil-effluent interface, since it is important the effluent be distributed equally throughout the filter bed. Reviewing the percolation and more particularly, the application rates described in Table 2 on Page 7,we find an application rate of 0.643 gallons/ftp/day that will theoretically occur at the soil-effluent interface. Although each dose volume is calculated below,this will ultimately be dependent upon the final float settings. If we take a maximum theoretical single dose of 350 gallons, deposited equally over one filter bed area of 950 sq ft(see below), the application rate is 350_950= 0.368 gallons/ft, which is 57%of resultant application rate test result. Consequently, pooling should not occur. E.L.F. SEPTIC TANKS Septic tanks store the accumulated sludge, scum and effluent (clear zone) volumes, which in tum affect treatment of nitrogen within the tanks. In the following calculation,the pump-out interval factor times the%vE time the peaking factor(PF) correlate the pump-out time interval in years with the recommended tank capacity. The peaking factor value for this project is estimated to be 2.5. Septic Tank Capacity Based on Puma-out Interval of One Year: Recommended tank capacity for a potential pump-out interval of one year after complete build-out: 1.6(pump-out interval factor)(QAVE) x Peaking Factor(PF=2.5) = 1.6 (1,586 gals/day) x 2.5 =6,344 gals. Total septic tank capacity=three - 2,000 gallon tanks=6,000 gallons. Detention Time: Detention Time=6_,000 gal total tank capacity x 0.70 (30%volume lost to sludge/scum accumulation) 2.5 (Peaking factor)x 1,586 gals/day(ADF) LDetentione= 1.1 days. The minimum acceptable detention time is 1.0 day. 17 Chesney Consulting