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rIn addition to measuring the permeability of the soils through percolation testing, a soil sample was etrieved from the perc test boring to test for chemical characteristics and soil particle size analyses of the native soil. A sample of the sandy loam soil to be imported was also retrieved for the same analyses. The native soil chemistry reveals normal percentages of cation saturation. If the magnesium percentage was found to be significantly higher, impedance of permeability would have occurred. The magnesium content of the import soils is high which may slow the permeability of this soil to an indeterminable extent. In comparing the saturated hydraulic conductivity(K.)of both soils (native and import)as estimated through the particle size analyses,the following data can be concluded: The soils in the United States are generally placed into four Groups: A, B, C and D and three dual classes A/D, B/D and C/D. The native soils can be classified in Group A in which Ksat is very high. These soils have less than 10%clay and more than 90% sand,which is illustrated on the Particle Size Analysis found in Appendix A. The Kiat exceeds 5.67 inches per hour(iph). The import soil can be classified as Group B. These soils typically have between 10%and 20% clay and 50%to 90% sand,which correspond with the particle size analysis. The Kiat ranges from a low of 1.42 iph to 5.67 iph for this soil. Using the median value between this range, 3.6 iph is derived. This is equivalent to 16.7 minutes/inch(mpi). Since 1 ft of import soil is proposed to be emplaced, it will take approximately 200 minutes(3.3 hrs) for the effluent to percolate through this import soil, versus 6.7 minutes through 1 ft of the native soil, as determined from the perc test results by AdvancedGeo. ONSITE WASTEWATER TREATMENT SYSTEM DESIGN: OPERATIONAL COMPONENTS AND PARAMETERS To mitigate the excessive nitrate loading (as calculated) from the proposed OWTS,the following design parameters are presented: It is well-documented by a number of researchers that a mound effluent disposal system reduces nitrogen concentrations,with reductions ranging from 32%-70% (Converse, J. C.,Magdorf, F. R., Eastburn, R. P.). My design is basically a mound system constructed at-grade instead of above grade. The native soils will be used as the aerobic zone to promote nitrification, while 1 ft of imported soil with sandy loam(silt)characteristics will be emplaced below this sand layer to create an anaerobic zone, thus promoting denitrification. Design components are illustrated on the attached plans. By using a median nitrogen reduction of 50% from the researcher's data, in combination of increased septic tank size, should reduce the nitrate loading to below the MCL of 10 ppm NO3-N: 19.88 x (1 - 0.5) =9.9 ppm NO3-N (resultant recharge concentration). Increased tank size should lower N concentration further, with periodic pump-outs. The plans illustrate an existing 1,600 gallon septic tank that was installed in 2006 on the premise that a second unit dwelling was to be installed, which never occurred. This tank is located 43 ft north of the modular home,with effluent flowing to a future 480 sf filter bed directly west of this tank(160 required LFLL x 3 Soil Factor=480 sf). The 1,600 gallon tank is 33% larger than a required 1,200 gallon tank which will increase organic matter retention,thus providing an additional decrease in nitrogen loading. Page -2- Chesney Consulting