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r7OPERATI'ONAL SPECIFICATIONS ber to Filter Beds: The second compartment of the septic tank will be the pump,or dosing chamber for the two separate filter beds. One Orenco BioTube®Filter Pump Vault PN: PVU57-1819 with Duplex Effluent Pump System: PN: P300511, %HP,30 gpm, 115 Volt contained within BioTube Pump Vault. Duplex Control Panel PN: DAXICTXX. Laterals for Each Filter Bed: Sch.40 PVC 1.0"nominal diameter, 1/8" orifice directed at 12 o'clock. PVC laterals will hang from the tops of the Chambers. Effluent will squirt to the tops of the Chambers and trickle down the parabolic sides and over the louvers. Orifice spacing=3.0 ft,with laterals 40 ft long. "Turn-ups"or ball valves at the ends of each lateral for clean-outs contained within valve cover boxes, or otherwise accessible. Orifice Discharge Rate: 1/8" with 5 ft residual head=0.43 gpm 40 ft_3.0 ft= 14 orificesilateral x 0.43 gpm/orifice=6 gpm/lateral i i I An anti-siphon assembly(Model HVAS125)must be used if for an unforeseen reason there must be pumping to an elevation that may cause siphoning. Network Discharge Rate(NDR)For Each Filter Bed=3 laterals x 6 gpm/lateral -18 gpm i Transport Line= 1.25" Sch. 40 PVC, 25/45 ft length Manifold for Each Filter Bed= 1.25" Sch.40 PVC, 10 ft length i Monitoring of Each Filter Bed: Monitoring of effluent shall be with four monitoring ports within the filter bed area. Two monitoring ports are to be observation tubes,with the other two monitoring ports to be soil sampling ports. Observation tubes: 4" PVC Tee at soil/effluent interface with 4" riser extending above the soil/grass surface,with a screw type cap. Soil sampling tubes: 4" PVC pipe extending to soil/effluent interface with 4" riser extending above the grass surface by at least 0.5 foot,with a screw type cap. IV. CONCLUSIONS AND RECOMMENDATIONS SSS§5.4. The soils underlying the proposed filter bed disposal to serve the new Office Building Eska ceptional permeability that exceeds EHD regulations. The EHD regulations specify any perc rate less than 2 min/in as being too rapid. As referenced in Table 2,the official perc rate was 1.6 min/in. Rapid permeability is also referenced in the EPA Design Manual: Onsite Wastewater Treatment and Disposal Systems,pg. 213 stating that soils"with perc rates less than 1 min/in can be used for trenches and beds if the soil is replaced with a suitably thick(>2 ft) layer of loamy sand." Since a silty sand is indigenous, a 2 ft thick loam(sandy silt/silt) soil must be imported in the two filter bed areas. The EHD concurs with EPA's determination. By importing loam material with slower permeability, this will be theoretically beneficial for the mitigation of nitrification. As the effluent percolates through this loam material, it will encounter the native coarser sand material below this import material. As it encounters this coarser fraction, water will not immediately enter this stratum. Soil above it must become relatively saturated before water will flow into this coarser material. This can create saturated soil microsites that are anaerobic and conducive for inhibiting nitrification and promoting denitrification for ammonium molecules that have nitrified. 14 Chesney Consulting