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, r7 V. CONCLUSIONS AND RECOMMENDATIONS The following list summarizes the nitrate loading mitigation factors that are naturally occurring, or have been factored into the engineered septic system design: 1. Beginning with the septic tank, it was calculated that a 2,000 gallon tank size is sufficient for detention time and the lowing of nitrogen loading by.anaerobic digestion. This decrease in nitrogen concentration is approximately 10%to 20% less than the inflow nitrogen concentration. 2. The soil-effluent interface under the proposed Infiltrator Chamber trenches indicates a soil with fairly optimum characteristics for the suppression of nitrification. The clay content is sufficient to promote anaerobic environmental conditions for the prevention of nitrification and the promotion of denitrification, along with a favorable cation exchange capacity, organic matter and nitrate-nitrogen content. 3. The Infiltrator Chambers proposed for installation has the benefit of creating saturated, anaerobic conditions as effluent dribbles into the Chambers from the D-box, thus preventing nitrification and promoting denitrification of any nitrate molecules that may have formed within the septic effluent. 4. The importation of sawdust or organic compost material must be implemented. Two inches of this material are to be placed on the floor of the Chamber trenches and then raked into the soil. Raking and incorporation must be done since it has been directly observed that just laying the O.M. on the soil-effluent surface creates a manufactured biomat material, thus slowing permeability. The O.M. will greatly increase the carbon to nitrogen(C:N) ratio of the soil at, and within the two-inch depth of the soil-effluent interface. These materials can exceed a C:N of more than 100. Nitrification will only occur if the C:N is below 20. Additionally, ammonium that may have nitrified, will denitrify within the anaerobic environment, and high carbon material within the interface due to saturated conditions promoted by the organic mater' �i h trator Chamb The application rate was determined from the perc rate to be 0.643 gai�o�sltt/day. he total length of the Infiltrator trenches is 492 ft, or 984 ft' of floor area. Therefore, the trenches can mange: 0.643 gallons/ftz/day x 984 f12= 633 gpd. The obtained perc rate suggests a minimum soil depth from the soil-effluent interface to the groundwater is to be eight ft. The seven-ft septic tank excavation depth was observed several days after excavation. No capillary water was observed,thus placing the closest groundwater at a nine-to- ten ft depth. Considering the Chamber trenches are 2.5 ft deep indicates sufficient effluent travel distance exists. In addition, the addition of the O.M. will no doubt slow effluent infiltration and percolation, which is commonly observed in agricultural environments where O.M. is added to retain irrigation water. All decentralized wastewater management systems (septic systems)will eventually fail. A reasonable long lifespan for the primary and ultimately the reserve area replacement system can be expected based on the findings and design factors found in this report. Page 5 of 13 Chesney Consulting