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FFdensity veal a low nitrate concentration of 8 ppm. The Maximum Contaminant Level 3 in drinking water is 45 ppm. This concentration may be considered a oncentration that has accumulated over eons. The 8 ppm concentration can be he deep groundwater, high clay content intervening strata, very low septic system o intense (fertilized) agriculture surrounding the property. CONCLUSIONS The perc test results for Parcels 1, 2, 3 and 4 show acceptable percolation for the management of septic effluent flows. However,the depths at which acceptable percolation was obtained on each of the four proposed Parcels varies. This can be attributed to the incredibly variable soil substructures that may have occurred during gravel mining operations that may have taken place on the subject property. It may be that importation of spoils, etc., has created the observed variability in permeability. Nevertheless, the referenced EHD soils map indicates that leachlines and seepage pits (not sumps) should be installed in this locale. Although the Pere tests were conducted at depths typically representative of sumps, seepage pits are recommended for a number of reasons: 1.) They are the typical and principle effluent management structure installed in this area, 2.) There is a significant distance of 105 feet between the bottom of a seepage pit at 25 feet b.g.s. and the current groundwater depth of 130 feet, 3.) Seepage pits allow head pressure buildup to force effluent into the anaerobic clay soils from 15 feet to 25 feet, 4.) If effluent levels rise above 10 feet from the bottom of the seepage pit, the effluent would then be managed by the more permeable silty gravel strata encountered in the areas with acceptable deeper perc tests. As stated above, EHD requires that there be sufficient distance for"treatment'of septic effluent before it encounters the groundwater table. This distance is normally regarded to be five feet in leachlines and 10 feet with seepage pits. Therefore, sufficient distance exists between the bottom of a maximum depth seepage pit and the current groundwater depth of 130 feet. It is recommended that Infiltrator® Chambers be considered for installation for the new septic systems on each Parcel to keep the soil/effluent interface as high in elevation as possible and to take advantage of the evaporative and evapotranspiration capacity during favorable weather conditions throughout the year. The actual number of Infiltrator Chambers or conventional leachlines and septic tank sizes are unknown at this time since the number of bedrooms for each structure is unknown. Each new system must have at least a 50% standby replacement area incorporated into the design of the septic system, and it may be prudent to designate a 100%replacement area due to the poor soils in this locale. It is recommended that a larger replacement area be designated since it is particularly evident from the Repairs/Addition permit data that septic systems have a definite lifespan on the property, in addition to the possibility that "mound systems"may eventually have to be installed. All related septic system structures and the new domestic wells must comply with the published "distance" requirements from property borders,roads, irrigation fields and irrigation ditches, etc. Pae -4- Chesney Consulting