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Due to the fact the imported loam material will have a significant silt percentage, there is the potential for the soil-effluent interface to "silt-over" and hinder or prevent the infiltration of septic effluent. Consequently, a 2.5 inch layer of washed sand(not on-site native sand material)must be placed on top of the imported loam(silt)material,with the Infiltrator Chambers placed on top of the wash sand bed. Care must be given to the imported silt material and washed sand bedding. This material should not be mechanically compacted; however, it should not be loose. If the material is too loose, as effluent percolates through this material, it could compact to an extent that may damage the piping system. Hardpan stratum was not encountered in the deep drilling procedures. It is highly unlikely that a restrictive stratum exists down to the water table depth at approximately 20.5 ft. NLS§4. �,S S§ 6rom the soil chemistry test results, it appears that denitrification potential wild evere restn5led due to the sandy soil structure. However, as explained above, there should be some mtrafe loading mitigation potential by the importation of the silty loam material. The denitrification potential in combination with comparatively shallow-rooted landscape plants in the filter bed area should also reduce nitrate impact by evapotranspiring and mineralizing a percentage of the effluent during favorable weather times of the year(i.e.,April through September). The well water analytical chemistry results obtained from the on-site domestic well indicate that the nitrate impact to the underlying aquifers is not as high as would be expected. This assumption is based upon the large agricultural production land area directly upgradient to the project site. This lower-than-expected nitrate concentration may be attributable to substantial clay strata above the aquifer(s) from the depth of the well intake, or a high denitrification potential within the underlying aquifers. SSS§ 6.8. The Average Daily Flow is calculated to1 4 gals/day from the Office Building. The Applicat' n Rate at the native soil-effluent interface i 1. Is/ft/day based upon the obtained perc rate of 1.6 in/in at the 36 inch depth. However,the ifilpo ed loam material should possess a perc rate of roximately 25 min/in,which should translate to Application Rate of approximately 0.593 gals/ft'/day. NLS§4.1 The nitrate loading potential c (Mate Page 12 indicates the percolating effluent may have a resultant nitrate concentration of 6.2 ppm which is below the drinking water Maximum 'Contaminant Level f tL). The underlyin ound ater aquifers contain a nitrate concentration of approxima y 27.8 nitrate. Consequently, a recharge effluent water should theoretically add a dilution e o the aquifers that were tested. This is theoretical and based on the assumption that water table receiving waters eventually percolate into the lower aquifers. The following information discusses this premise: Regarding the calculated nitrate-nitrogen loading potential to the underlying groundwater table, it is important to recognize that when adding one concentration of a solute(i.e.,NO3-N concentration determined in the effluent recharge) to another concentration of a solute(i.e.,NO3-N concentration 15 Chesney Consulting