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FF,senches sections of leachline pipe=4,000 square foot leachfield of leachline failure, a sump may be installed for future expansion. The leachT aced as high in elevation as possible. Trench depth should be 24-42 inches. and sumps should consists of the following surface area: Each trench=4 ft'trench sidewalls+2 ft' bottom of trench x 100 ft length= 600 ft' x 4-100 ft sections=2400 ft' surface area for effluent infiltration. Several scientific studies have demonstrated that the infiltration capacity of a soil absorption system is dependant primarily by the formation of the biomat and not by the permeability of the soil. The biomat is a biological, slimy substance which forms on the soil-effluent interface over time. Hydraulic loading rates range from a conservative criterion of 0.125 gal/ft2/day to 0.5 gal/ft2/day for a percolation rate of approximately 1 min/in. These application rates are based on trench side wall areas only. IMPACT MITIGATION Nitrate-nitrogen impact from a future septic system should be mitigated by the following design criteria: First, by using a 1,600 gallon septic tanks,there will be a higher percentage of solid organic material trapped within the tank. Additionally,a filter may be installed on the second compartment(e.g. Zabel®or OSI®Filters) before the effluent flows (or is pumped)to the leachfield. There is evidence that septic tanks have the capability to denitrify nitrate: As influent enters the first tank,the wastewater has been aerated from flushing action, and from the aerator on a faucet, etc. But as the oxygen is consumed by microbiological processes, the tank becomes anaerobic and the microbes begin to use nitrate as an electron acceptor. If the effluent is allowed to remain in the second compartment for a longer period of time, denitrification may be theoretically promoted. The leachlines should be placed as high as possible within the leachline trench,preferably 12 inches below grade. Filter beds may be used if disposal area is constrained. However, there must be a 100%replacement area incorporated into the design. IV. CONCLUSIONS AND RECOMMENDATIONS It is our opinion the subject site is suitable for its intended use with regard to septic effluent management. The potential environmental impact from future nitrate-nitrogen loading may be mitigated to an acceptable extent by the use of a larger septic tank and high elevation leachfield. The percolation rates obtained indicate a permeable soil. Effluent management is based on the permeability of the soil eventually reaching an long term application rate (LTAR) of L proximately 0.5 to 1.0 gals/ft2/day due to biomat formation. It is imperative that if a repair is de or an additional system installed,the underlying soil should be investigated for a hardpan 6 Nadey Ag Research