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,- . %we '-.00'.i Peaking factors for users on septic tanks vary with usage during the hour of the day, and day of the week. Peak hourly rates are associated with normal working hours. The ratio of the peak day to the average day can vary from 1.5 to >5, depending upon the usage. However, peaking factors are not as relevant since the effluent pump will dose on demand. A peaking factor of 2.5 (average between 0 and 5)will be used in the calculation below: Septic Tank Hydraulic Detention Time Detention Time=4.000 gal septic tank capacity x 0.70(30%volume lost to sludee/scum accumulation) 2.5 (Peaking Factor)x 1,000 gals/day ADF Detention Time= 1.12 days. The minimum acceptable detention time is 1.0 days. Filter Bed Area The filter bed area is normally calculated under Section 8.7 of the San Joaquin County Sewage Standards and EHD Document 42-01-004: Calculation Requirements for Commercial Septic Systems: Base Tank Capacity (BTC) = 1,200 gals Lineal Feet of Leachline (LFLL)= 1,200 BTC + 1,000 ADF x 0.20 SF =440 LFLL Filter Bed Area=440 x 3 = 1,320 square feet. The filter bed area should be square in area: 40 ft x 40 ft= 1,600 sq. ft. The filter bed area should also correspond with the percolation, and more particularly, the infiltration test results. As referenced above, the application rate correlated with the infiltration test results, is 0.857 gals/ftz/day. Using the ADF of 1,000 gpd_0.857 gals/ft2/day= 1,167 sq. ft filter bed. Therefore, the filter bed size of 1,600 sq. ft. based on the Sewage Standards is applicable. Wastewater Disposal System Parameters and Appurtenances Zabel or Orenco Filtration from second septic tank to filter bed(EHD Requirement) Duplex pump system (EHD Requirement) Flowmeter on effluent pumped to filter bed(EHD Requirement) Distal end clean-outs on each lateral (EHD Requirement) As-Builts of entire system by installer after installation(EHD Requirement) Monitoring of effluent with monitoring ports or wells within, or on the perimeter of the filter bed area. Observation tubes: 4" PVC Tee at soil/effluent interface with a 4" riser flush with the grass surface and a screw-type cap. (EHD Requirement) 1.5 inches of peat at soil/effluent interface (EHD Requirement) Filter Bed Area=40 ft north/south and 40 ft east/west= 1,600 sq. ft. Filter bed should be at grade with surrounding soil surface. Laterals: 7 laterals, Sch. 40 PVC, 1.5" nominal diameter, 5/32" orifice directed at 12 o'clock with 3" PVC orifice shield Zabel Part No. PDS-ZOS-125/150, 4.0 ft orifice spacing, each lateral 36 ft long. Orifice Discharge Rate: 5/32" with 5' residual head=0.64 gpm 36 ft-4 ft= 9 orifices/lateral x 0.64 gpm/orifice= 5.8 gpm/lateral Page -9- Ckesney Cxwdting