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03 June 2021 Rnfaij Project No. 21-6431 Page 15 of 15 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). • Avoid use of bioattenuation chemicals (bleach etc.). • Properly and regularly maintain the property septic system. • Use EHD criteria for sizing the septic disposal field. • Utilize an advanced treatment system to reduce nitrate loading and the percolation rate. 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. • Nitrates were detected below the State of California Maximum Contaminant Level in the onsite waterwell; and DBCP was not detected above the laboratory reporting limit. • All approved septic system use should follow the EHD Onsite Wastewater Treatment System Standards. 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 were based on field testing results. Evaluations of the hydrogeologic conditions at the site for the purpose of this investigation were made from a limited number of available data points (i.e., test hole and field data) and subsurface conditions may vary away from these data points. No other warranty, expressed or implied, is made as to the professional interpretations, opinions and recommendations contained in this report.