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1 FFAnalyticalata obtained from septic tank effluent should also correlate with this ratio unless ogen (Nz) was liberated or consumed by microbes. Calculations of nitrogen:argon ned from the analyses of seven different effluents indicate ratios of 100, 60,43, 50, 1. All of these values exceeded the expected nitrogen:argon ratio of 37 and indicate nitrogen liberation. This data supports the theory that denitrification occurs within septic tanks and by using two tanks in series, encourages denitrification. IV. CONCLUSIONS AND RECOMMENDATIONS It is our opinion the subject property is suitable for its intended use with regard to septic effluent management. The percolation rates obtained indicate a permeable soil, although permeability decreases with an increase in soil saturation. Effluent management, and therefore design should be based on the permeability of the soil eventually reaching a long term application rate (LTAR) of approximately 0.5 to 1.0 gals/ftZ/day due to biomat formation. It is imperative that a 100% replacement area be designated in the event a repair is needed or an additional system installed. Sumps may be used if there is an increase in the number of people using the system, leading to greater wastewater flows than those anticipated in this report. It may be a requirement by the Environmental Health Department to install a flow meter on the system. The nitrate loading calculations demonstrate groundwater under the leachfield, to a thickness of 2.5 feet, will be theoretically impacted above the current Maximum Contaminant Level Drinking Water Standards (MCL/DWS)by 3.5 ppm NO3-N. Nitrate influence from the proposed facility can be considered "reduced impact" when it is considered on an areal basis and in comparison to maintaining the property in alfalfa production, as explained: Alfalfa requires 480 pounds of nitrogen per acre to produce 8 tons. The alfalfa plant has the capacity to manufacture its own nitrogen, although from this process, excess nitrogen is leached past the root zone. It is difficult to quantify the amount leached due to the number of factors involved; however, 50 pounds per acre can be regarded as probable, particularly if additional nitrogen is supplied. Therefore, the possibility exists for 50 lbs N x 40 ac=2,000 lbs of nitrogen to leach into the groundwater under the subject property if left in alfalfa production. The on-site domestic well is proposed to be installed downgradient from the leachfield. We recommend periodic monitoring of this well. If there is an increase in nitrate concentration, further treatment to prevent nitrification may be warranted. Potential environmental impact from future nitrate-nitrogen loading may be mitigated to an acceptable extent by the use of two - 2,000 gallon septic tanks in series and a filter(e.g., ZabelS or OSI® Filters) placed in the last chamber of the first septic tank. A denitrification potential of 20%-25% is projected within the soil environment due to the referenced soil characteristics of silty clays, clayey silts. Bottled water should be consumed for drinking and cooking purposes by the people residing in the house adjacent to the west side of subject property. Improved management procedures should be established for the offloading, storage and mixing of fertilizers on this property. 8 Na!!ey sig Research