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30 July 2019 AdvancedGeo AGE Project No. 19-4772 Environmental Page 13 of 14 9.7. IMPACT OF NITROGEN LOADING FROM SITE PROJECT TO DOWNGRADIENT WATER SOURCES The recharging of groundwater is the most likely potential feature that could impact future nitrogen loading. Since the subject property is flat, AGE does not anticipate percolating effluent will affect any nearby water sources. Based on the volume of wastewater to be generated, the potential vertical migration would not likely degrade the local groundwater. A total of 9.66 parts per million (ppm) of additional nitrogen is estimated to be added to the site over the long term through waste water recharge from the existing and proposed septic systems. 10.0. TOTAL NITRATE IMPACT FROM PROPOSED PROJECT Based on the method and assumptions described, proposed NO3_N mass of wastewater and the calculations of the NO3 N loading predicted, the existing and proposed development should not negatively impact NO3_N loading rates within the aquifer. The soil at the site appear to be adequate for nitrate degradation and proper leaching of wastewater. A total of 9.66 ppm of additional nitrogen is estimated to be added to the site over the long term through waste water recharge from the existing and proposed septic systems. 11.0. MITIGATION METHODS PROPOSED To mitigate any known or potential future impacts to soil and groundwater of nitrate from the existing and proposed septic systems, the following mitigations could be implemented: • Maximize wastewater hold time where practical (retention). • Avoid use of bioattenuation chemicals (bleach etc.). • Properly and regularly maintain property septic systems. • Use EHD criteria for sizing the septic disposal field. If re-location or expansion of leach fields becomes necessary, leach lines should include high organic substrates under and surrounding the lines installed. 12.0. CONCLUSIONS Based on this Soil Suitability and Nitrate Loading Study, AGE concludes the following: • All approved septic system use should follow the EHD On-Site Waste Disposal Standards.