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CONCLUSIONS AND RECOMMENDATIONS The shallow subsurface soils underlying the subject property where the new trench disposal area is to be installed, reveals a fine loamy sand soil structure with rapid permeability. Knowledge of an underlying cemented silts hardpan stratum was verified and has been documented as providing a natural attenuation to the rapid percolation/permeability of the native soils before the effluent enters the underlying water table. As noted on the Soil Analysis Report,the surface and subsurface soils possess sufficient alkalinity to influence ammonium stability. Ammonia may be preferentially created,thus impeding nitrification of ammonium to nitrate (Ref. 4). Additionally, it has been observed on other projects,that significant denitrification occurs directly above hardpan strata, potentially due to anaerobic conditions,thus promoting denitrification. Unfortunately,the subject property has not been under agricultural production for decades, so this determination could not be made. The nitrate nitrogen concentration throughout the soil profile is very low at 1 ppm. Additionally,the magnesium concentration in the hardpan stratum is high which causes sand particles to bind together and impede percolation. Nitrate loading should be attenuated by at least 30% due to the installation of a 2,000 gallon septic tank,relative equal distribution throughout the leachline trenches under time-dosing, and promotion of denitrification above and through the hardpan stratum. This should now place the nitrate loading under the MCL of 10 ppm NO3-N(Calculated nitrate loading= 13.9 x (1- 0.3))_ 9.73 ppm NO3-N (§7.1.3). The leachline trench infiltrative area is considered to be 960 sf. Factoring a long term acceptance rate (LTAR) after biomat formation of 0.2 gals/sf/day, an acceptance rate in gallons per day(gpd) is calculated to be 192 gpd. Given a reasonable wastewater ADF generation of 70 gals/bedroom= 3 bedrooms x 70 gpd/bedroom=210 gpd(§7.1.3,4). Therefore, sufficient infiltrative area exists to manage the LTAR. All food waste must be handled as solid waste and disposed of in the garbage. All onsite wastewater treatment systems will eventually fail. A reasonably long lifespan of the disposal area can be expected based on the calculations demonstrated above,native soil characteristics,the perc rates obtained, and the innovative design factors of a low head pressure manifold system through the 3 leachlines. Consideration should be given to pumping the septic tank every three years to mitigate nitrogen loading by extraction of septage. Page -4- Chesney Consulting