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19 May 2021 <br />Project No. 21-6435 <br />Page 13 of 14 <br />nitrogen is estimated to be added to the site over the long term through wastewater <br />recharge from the existing septic system. The nitrogen loading value is below the desired <br />value of 10 ppm. <br /> <br /> <br />10.0. TOTAL NITRATE IMPACT FROM PROPOSED PROJECT <br /> <br />Based on the method and assumptions described, proposed NO3_N mass of wastewater <br />and the calculations of the NO3_N loading predicted, the proposed use should not <br />negatively impact NO3_N loading rates within the aquifer. The soil at the site appears to <br />be adequate for nitrate degradation and proper leaching of wastewater. A total of <br />9.80 ppm of additional nitrogen is estimated to be added to the site over the long term <br />through wastewater recharge from the existing septic system. <br /> <br /> <br />11.0. MITIGATION METHODS PROPOSED <br /> <br />To mitigate any known or potential future impacts of nitrate to soil and groundwater from <br />the proposed septic system, the following mitigations could be implemented: <br /> <br /> Maximize wastewater hold time where practical (retention). <br /> Avoid use of bioattenuation chemicals (bleach etc.). <br /> Properly and regularly maintain the property septic system. <br /> Use EHD criteria for sizing the septic disposal field. <br /> Utilize an advanced treatment system to reduce nitrate loading and the percolation <br />rate. <br /> <br />If re-location or expansion of leach fields becomes necessary, leach lines should include <br />high organic substrates under and surrounding the lines installed. <br /> <br /> <br />12.0. CONCLUSIONS AND RECOMMENDATIONS <br /> <br />Based on this Soil Suitability and Nitrate Loading Study, AGI concludes the following: <br /> <br /> The percolation rate meets the minimum EHD standards in the proposed septic <br />system disposal field. <br /> The nitrogen loading rate is below the desired value of 10 ppm. <br /> All approved septic system use should follow the EHD Onsite Wastewater <br />Treatment System Standards. <br /> <br />