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Soil Suitability&Nitrate Loading Evaluation CTE Job#25-1084G <br /> New Septic Leech Lines <br /> 21850 East Liberty Rd <br /> Clements, California <br /> January 30, 2021 (Revised 1/17/2022) Page 8 of 9 <br /> 10.0 CONCLUSIONS <br /> A suitable percolation rate for conventional onsite waste water treatment system in San Joaquin <br /> County is defined as stratum capable of percolating water between 1 and 60 minutes per inch <br /> (min/inch) at a depth of up to 3.5 feet below existing site grade. CTE's percolation test results at <br /> the proposed leach field was 60 min/inch at a depth of 36 inches and the proposed back up leach <br /> field was 30 min/inch which is within the acceptable range for a suitable rate indicated by the San <br /> Joaquin County. Mitigation by system design or enhancement is not required for parcels with <br /> percolation test results meeting these criteria. High groundwater level is expected to be at <br /> approximately 121 feet depth at the site/vicinity which is well below the advisable groundwater <br /> depth for a typical 42-inch deep dispersion field with percolation rates indicated. Low-moderately <br /> permeable soils (e.g., silts and clays) also provide adequate treatment of the percolating <br /> wastewater. <br /> As stated in Section 9.0 above, CTE estimates that the potential nitrate-nitrogen (N) concentration <br /> in groundwater resulting from the new leach field should be below the State of California drinking <br /> water standard of 10 mg/L. <br /> Based on these results, it is our professional opinion that soil conditions are adequate for use of a <br /> conventional septic tank/leach trench sewage disposal system; therefore, an alternative system will <br /> not be required. <br /> 11.0 LIMITATIONS OF INVESTIGATION <br /> The field evaluation and geotechnical analysis presented in this report have been conducted <br /> according to current engineering practice and the standard of care exercised by reputable <br /> geotechnical consultants performing similar tasks in this area. No other warranty, expressed or <br /> implied, is made regarding the conclusions, recommendations and opinions expressed in this <br /> report. <br /> %7C-A L.I N CC <br />