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In comparing the saturated hydraulic conductivity (Ksa) of the soil samples referenced in Table 1 as estimated through the particle size analyses, the following data is obtained: The classification of soils in the United States and the world is highly complex; however, soils in the U.S. have been generally placed into four Hydrologic Soil Groups (HSG) by the Natural Resource Conservation Service (NRCS) for runoff and infiltration purposes: A, B, C and D and three dual classes AID, B/D and C/D. Soils from the 0-12" depth can be classified in Group D in which 'cat is low. These soils have less than 50% sand and can have more than 40% clay. The Ksa, ranges from 0-0.05 inches per hour (in/hr). Soils from the 30-36" perc test stratum can be classified as Group A. These soils typically have between 10% and 20% clay and 50% to 90% sand, which corresponds with the particle size analysis. The Ksa, exceeds 5.67 in/hr (10.6 min/in) for this soil type. Soils from the 48-54" stratum soil can be classified as Group B, and is typically composed of the fine soil fractions (approximately 40% silt and 10% clay). Ksa, ranges between 1.42 in/hr and 5.67 in/hr. The median value between this range is 3.6 in/hr. This is equivalent to 16.7 minutes/inch (mpi). The depth of the stratum is unknown, but at least six inches. Therefore, it will take approximately 100 minutes (1.67 hrs) for the effluent to percolate through this six-inch depth of this silt loam soil (and almost assuredly a much deeper silt loam depth). CONCLUSIONS AND RECOMMENDATIONS The soils underlying the highly permeable 30-36" stratum reveal a silt loam soil structure, which will provide a natural attenuation to the rapid percolation/permeability of the native soils before the effluent enters the underlying water table. NRCS data indicates the perc rate for this silt loam soil type to be approximately 16.7 mpi. From Table 1.10.2 in the SJC OWTS Standards, a Minimum Soil Depth from the floor of the disposal system to the water table must be a minimum of 8 feet, based on this perc rate. Since the Pinnell's are proposing to install a modular home, this separation distance can be achieved since the influent line can enter the soil to meet the septic tank set at-grade, so that the connection is 14 inches below ground surface. Two inch fall through tank, one inch to the D-box, two inches through D-box, 2 inches to and through the perforated pipe, 12" drain rock = 33 inches (2.75 ft). Groundwater was measured at 10.33 ft - 2.75 ft = 7.58 ft. Therefore, the septic tank shall be installed six inches above natural, existing grade so that the 8 ft minimum separation distance can be maintained. The modular home is to consist of two bedrooms. Consequently, a 1,200 gallon septic tank can be installed, with 200 lineal feet of leachline, or a 600 sf filter bed (24.5 ft square). Page -2- Chesney Consulting