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B. Proposed Wastewater Disposal System Overview and Design Specifications The following describes the proposed new wastewater management system sequentially starting with the existing septic and grease trap tanks, which will remain. The effluent will then gravity flow into a new pump basin with a BioTube® Filter Pump Vault and a duplex pump system. i. Septic Tank Hydraulic Detention Time Calculation Detention Time= 1600 gal septic tank capacity x 0.70 (30%volume lost to sludge/scum accumulation) 2.5 (Peaking Factor)x 350 gals/day ADF Detention Time= 1.3 days. The minimum acceptable detention time is 1.0 days. This excludes hydraulic retention time that can be attributed to the grease trap tank. ii. New Disposal System Design Parameters and Appurtenances All components and part numbers (Orenco/Pace Supply) are specified on the plans. The effluent will be filtered by the BioTube filter vault before pressurization for disposal through the lateral orifices. The duplex pump system within the BioTube will alternate between on/off. Total effluent volume can be verified by checking pump cycle times on the panel to ensure both pumps distributed effluent equally. Laterals in the filter bed are to consist of 7 laterals of varying length (See plans), but with an average length for calculation purposes of 12.6 ft. Sch. 40 PVC 1.0" nominal diameter, 1/8" orifices directed at 12 o'clock, 3.0 ft spacing. Flushing assemblies are to be installed at the ends of each lateral for clean-out and contained within valve cover boxes. Geotechnical filter fabric must be installed over the drain rock after 2 inches of rock has been placed over the laterals with orifice shields. The "Pump Selection for a Pressurized System Parameters and Chart"found in Appendix E illustrates the selected parameters for the new disposal system, along with the calculations for frictional head loss, pipe volumes and pump curve. If the manifold and laterals are ultimately installed at a higher elevation than the transport line, a check valve must be installed either on the transport line or discharge assembly. iii. Primary and 100% Replacement Effluent Disposal Area Filter bed area is calculated by the procedure described in 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+ 350 ADF x 0.225 Silt SF = 350 LFLL. 350 LFLL x 3 = 1,050 sq. ft. filter bed. Due to area constraints imposed by the neighboring domestic well to the southwest, only half of the area available for disposal can be used, as depicted on the engineering plans and discussed in the Conclusions Section of this report. Page -3- Chesney Consulting