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AdvancedGeo <br /> 12 October 2020 An Employee-Owned Company <br /> Project No. 20-6164 <br /> Page 14 of 15 <br /> 10.0. TOTAL NITRATE IMPACT FROM PROPOSED PROJECT <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 development should <br /> not negatively impact NO3_N loading rates within the aquifer. The soil at the site appear <br /> to be adequate for nitrate degradation and proper leaching of wastewater. A total of <br /> 9.85 ppm of additional nitrogen is estimated to be added to the site over the long term <br /> through wastewater recharge from the proposed septic system. <br /> 11.0. MITIGATION METHODS PROPOSED <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 /> • 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 /> 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 /> 12.0. CONCLUSIONS AND RECOMMENDATIONS <br /> Based on this Soil Suitability and Nitrate Loading Study, AGI concludes the following: <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 /> • Nitrates were detected below the State of California Maximum Contaminant Level <br /> in the onsite water well. <br /> • All approved septic system use should follow the EHD Onsite Wastewater <br /> Treatment System Standards. <br /> 13.0. LIMITATIONS <br /> Our professional services were performed using that degree of care and skill ordinarily <br /> exercised by environmental consultants practicing in this or similar localities. The findings <br /> were based on field testing results. Evaluations of the hydrogeologic conditions at the site <br /> for the purpose of this investigation were made from a limited number of available data <br />