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Soil Suitability&Nitrate Loading Evaluation CTE Job#25-1256G <br /> New Septic Leech Lines <br /> 9490 E Schmeidt Rd <br /> Lodi, California <br /> June 29, 2022 Page 8 of 10 <br /> R = Average recharge rate due to rainfall for the water years 2015 through 2021 <br /> near the site (taken as 80% of annual 15.55 in/yr with 20% assumed lost to offsite <br /> drainage & evapotranspiration) <br /> = 12.44 in/year(average taken from Site ID BRCC 1 BEAR CK—APLINE RD <br /> https://www.cnrfc.noaa.gov/data/text/precip_goo_leg /PPS_So 2021.txt) <br /> (Replace the year in the link to get data for all years mentioned) <br /> Nb = Background nitrate nitrogen concentration of rainfall recharge at the <br /> water table typically falls between 0.5 and 1.0 mg/1 (per Hantzsche and <br /> Finnemore; 1992) and is assumed to be 1.0 mg/1. <br /> The nitrate loading calculation is as follows: <br /> Nc _ [I(NW) (1-D) +R(Nb)] /(I+R) <br /> NC _ [0.807 (40) (1.0-0.25) + 12.44 (1.0)] /(0.807 +12.44) = 2.77 mg/1 as N <br /> The calculated nitrate (2.77 mg/L as N) for groundwater Nitrate-Nitrogen Impacts is below the <br /> State drinking water standard of 10 mg/L for nitrogen (N). <br /> 10.0 CONCLUSIONS <br /> A suitable percolation rate for conventional onsite wastewater 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 20 min/inch at a depth of 36 inches which is within the acceptable <br /> range for a suitable rate indicated by the San Joaquin County. Mitigation by system design or <br /> enhancement is not required for parcels with percolation test results meeting these criteria. High <br /> % M <br /> 7CAALUNC <br />