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VI. CONCLUSIONS The project acreage consists of approximately 16.6 acres. This calculates to a yearly "per acre" contribution of nitrate-nitrogen from the Church of approximately 20 lbs. of NO3-N/ac/yr. It is our opinion the existing nitrogen content of the soil environment should not be considered since the organic matter(ENR-estimated nitrogen release) and soil nitrogen is currently low and will not be a significant factor if the project is developed. Using the Church's projected nitrogen loading and extrapolating it to potential environmental _ impact is difficult. This is because the proposed mound system for the Church is a "point source," unlike a housing subdivision on septic systems where impact is spread relatively equally over many acres. If the Church proceeds with the proposed mound septic system, mixing and dilution of the septic effluent within the upper aquifer groundwater should be considered, and an analysis of potential downgradient impact to domestic wells should be implemented by establishing baselines. It is interesting to note that the first groundwater, along with the neighboring domestic well has assimilative capacity for additional nitrogen impact. With agricultural production upgradient from the subject site, additional capacity was unexpected. This can probably be attributed to the heavy, clay soil in the upper soil horizon, and also throughout the upper zone of saturation. Therefore, it is our opinion that the projected impact of 20 lbs. of NO3-N/ac/yr is roughly equivalent to the amount of nitrogen leached in normal agricultural operations. Based upon the comparatively low nitrogen baseline levels encountered during this investigation, there is a small potential for downgradient domestic well impact. _ However, the other significant issue that must be addressed with nitrate loading is the proper operation of the proposed system, so there are no failures. A failure would include effluent "surfacing" from severe clogging mat formation, incompatibility with the import soil and native soil interface, climactic stress and groundwater mounding. As referenced, six feet of fill may have to be imported to raise the project above the flood plain and create the required soil elevation for the mound system. This import soil must possess specific characteristics for the proper operation of the mound system. Probably the most significant issue concerning potential failure with the proposed system is the native soil and high groundwater. As the effluent percolates through the mound, treatment occurs, then the effluent must enter the native soil, a heavy clay with low infiltration and percolation 8 Vaffey Ag Rgsearch