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FILTER BED DESIGN The primary and 100%replacement areas have been denoted on the Site Plan drawn for submittal to EHD and other County Departments. The new 1,200 gallon septic tank is to be installed near the southwest corner north of the property. After the effluent gravity flows from the septic tank, it will travel to a D-box to be equally distributed between the 800 ft2 filter bed. The 100% replacement area is denoted in the area that is presently a covered shed. This shed would have to be removed in the event of primary filter bed failure. CONCLUSIONS AND RECOMMENDATIONS NLS§ 4.2. "Yhe shallow subsurface soils underlying the subject property where the new filter bed is to be installed, reveals a very high clay content soil material with a high degree of denitrification potential. NLS§ 4.1 The nitrate loading calculations show the resultant effluent from the entire subject property will theoretically possess a concentration of approximately 23.3 ppm as nitrate-nitrogen, which is 2.3x over the Maximum Contaminant Level (MCL). Given that the ADF of 700 gpd has two extreme components promulgated by EHD of two people per bedroom, and that this flow volume will occur every single day of any given year, has created a very large nitrate loading r safety factor. This factor is conservatively estimated at greater than 2. Consequently, the nitrate loading mitigation procedure of placing four inches of a highly organic peat or a wood chip type material on the floor of the fed-must be implemented. This will - greatly increase the carbon to nitrogen (C:N) ratio of the soil at the soil-effluent interface. These materials can exceed a C:N of more than 100. Nitrification will only occur if the C:N ratio is below 20. Therefore,nitrification cannot occur from ammonium molecules entering the highly organic soil-effluent interface. Additionally, ammonium that has nitrified, will theoretically denitrify within the anaerobic environment and high carbon material within the interface due to saturated conditions promoted by the organic material. NLS§ 4.2. All decentralized wastewater management systems (septic systems) will eventually fail. A reasonable long lifespan of the primary and reserve area system can be expected based on the proposed components of the septic system. A nearby project that was con ed-ten years ago, found the underlying groundwater table to have a nitrate concentrat n of 97 mg/L. Given the large amount of surrounding agricultural production anA subsequent nitrogen fertilizer use, along with on-site septic systems,this nitrate concentration would be expected. Page 6 of 12