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F quiescent conditions within the front compartment of the existing 2,000 gallon tank, rgy within the force main must be mitigated. This can be accomplished by expanding h force main to four or six inch diameter PVC pipe 30 ft before entering the front septic rtment. Other methods of removing the energy may be considered. The tanks may be pumped on a prescribed interval basis depending on direct observations of paper and scum accumulation; e.g., every six months to every three years, depending on sludge/scum accumulation. Peaking factors for 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. A peaking factor of 2.5 is used in the calculation below for verifying the 1,200 gallon tank size: Septic Tank Hydraulic Detention Time Detention Time= 1.200 gal septic tank capacity x 0.70(30%volume lost to sludge/scum accumulation) 2.5 (Peaking Factor)x 360 gals/day ADF Detention Time=0.9 days. The minimum acceptable detention time is 1.0 days. A 1,200 gallon septic tank is adequate given the ADF safety factor volumes. Primary and 100% Replacement Filter Bed Area Engineers with Burns & McDonnell have formulated Design Calculations for this project that are found in Appendix D. The required filter bed area has been calculated to be 1,053 s£ The existing filter bed is 35 ft E-W x 40 ft N-S = 1,400 s£ This same area has been reserved immediately north of the primary disposal field for a replacement area. V. CONCLUSIONS AND RECOMMENDATIONS SSS§ 5.4, 6.8. The application rate of 0.80 gals/sf/day obtained from the perc rate indicates the indigenous soils can easily manage the calculated flow of 360 gpd: 0.8 gals/sf/day x 1,400 sf= 1,120 gpd. Permeability will undoubtedly slow as biomat formation occurs and will eventually slow to system failure. It is noted that all septic systems have a lifespan. The time frame to failure is unknown and unpredictable, and is dependant upon numerous factors. From the soil chemistry test results,there appears to be some denitrification potential within the soils, but not near as significant as has been observed in other areas of San Joaquin County. NLS§ 4.2, SSS§ 6.7. New standards have recently been enacted by EHD that were originally promulgated by the State Water Board concerning the minimum soil depth from the bottom of a disposal structure down to the water table. This minimum soil depth is contingent upon the perc rate. This new rule was a significant reason for this Addendum. The installed filter bed EHD Permit indicates rock emplacement from 24-42 inches in depth. 8 Chesney Consulting