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13 August 2021 Project No. 21-6530 Page 13 of 14 AdvancedGeo An Employse- Owned Ct M"Ay . - 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 20.17 ppm of additional nitrogen is estimated to be added to the site over the long term through wastewater recharge from the proposed septic system. 11.0. MITIGATION METHODS PROPOSED To mitigate any known or potential future impacts of nitrate to soil and groundwater from the proposed septic system, the following mitigations could be implemented: • Maximize wastewater hold time where practical (retention) by installing a larger septic tank (2,000 gallons). • Utilize an advanced treatment system to reduce nitrate loading and the percolation rate. • Avoid use of bioattenuation chemicals (bleach etc.). • Properly and regularly maintain the property septic system. • 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 AND RECOMMENDATIONS Based on this Soil Suitability and Nitrate Loading Study, AGI concludes the following: • The percolation rate meets the minimum EHD standards in the proposed septic system disposal field. • The nitrogen loading rate is above the desired value of 10 ppm. • All approved septic system use should follow the EHD Onsite Wastewater Treatment System Standards. • Coordinate with EHD personnel to determine if an engineered septic system is necessary to offset the elevated nitrate loading rate. 13.0. LIMITATIONS Our professional services were performed using that degree of care and skill ordinarily exercised by environmental consultants practicing in this or similar localities. The findings