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Values and Assumptions: 400 ag ls/day x 365 days/yr= 146,000 ga, ls/yr= 19,520 cu ft WW/yr = 1.1 in/yr I= 43,560 cu ft/Ac ft x 5.0 Ac x (1 ft/12 in) Nw= 112 mg N/L- 10%reduction in each septic tank=20%=90 mg N/L d = 10% from biomat formation and 25% from clay soil under filter bed Nb = Assumed to be 0.1 ppm NO3-N 1.1 in/yr(90 mg N/L) (I -0.35)+(9 in/yr x 0.1 mg/L) Nr = (1.1 in/yr+9 in/yr) Nr = 5.7 ppm as NO3-N or 25.5 ppm as NO3 The nitrate loading calculated for wastewater effluent recharge from the proposed facility is below the drinking water Maximum Contaminant Level(MCL) of 10 ppm NO3-N or 45 ppm NO3. The clay soil is projected to have at least a 25%denitrification potential. However, by taking advantage of a higher clay soil percentage at the 42 inch depth instead of the 24 inch depth, this denitrification potential may be even higher,possibly 30%-35%. In addition,the calculated effluent recharge concentration above does not account for nitrogen uptake by grass-type root structures that will absorb effluent at the Infiltrator Chamber louvers. The nitrogen uptake concentration is estimated to be between 15% and 25%during favorable weather conditions when the interior of the chambers is warm. This should cause evaporation of the effluent off the soil/effluent interface and onto the louvers for grass root transpiration uptake. Consequently, there is potential for the recharge effluent to be approximately: 15% additional soil denitrification, 15% zone of saturation denitrification, 20% evapotranspiration uptake= 15%+ 15%+20%= 50%x 5.7 ppm=2.9 ppm NO3-N. V. CONCLUSIONS AND RECOMMENDATIONS The soil physical characteristics under the proposed disposal area reveal a silty clay/clayey silt type surface soils with increasing permeability with increasing depth,based on the percolation test results. The soil at the 42-inch depth exhibited comparatively rapid percolation. By distributing the effluent through Infiltrator Chambers over the entire shallow filter bed area,the favorable characteristics of the clay surface soils can be taken advantage of, such as: 1.) Ammonium absorption, 2.)Anaerobic microsites within the clay lattices preventing nitrification and promoting denitrification for nitrification that has occurred, 3.)Unsaturated flow conditions, 4.)Increasing the distance between the soil/effluent interface and the encountered gravel stratum at 8.5 ft, and the depth to groundwater, and 5.) Greater likelihood of pathogen destruction to prevent contamination of the underlying groundwater. It is generally recognized from soil physics, that water percolating from a fine -grained soil into a coarser-grained soil will be impeded until near saturation is reached in the fine/coarse-grained soil interface. This is beneficial for the prevention of nitrification and promotes denitrification of ammonium molecules which may have nitrified. Chesney Consulting