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Soil Suitability / Nitrate Loading Study <br />Cherokee Memorial Park Vineyard Chapel Addition Ŷ Lodi, California <br />March 5, 2021 Ŷ Terracon Project No. NA207102 <br />Responsive Ŷ Resourceful Ŷ Reliable 18 <br />2.3 Sources and Impact of Nitrate to Groundwater <br />2.3.1 Current Off-Site Sources of Nitrate <br />Agriculture land use and septic systems in the area may be the most significant sources of nitrate <br />in groundwater. Septic tank use in the vicinity is discussed in Section 1.3.5. <br />2.3.2 Contribution of Rainfall <br />An estimate of the quantity and quality of rainfall was required for the nitrate loading analysis. <br />Average precipitation and potential evapotranspiration (ETo) data was obtained from the <br />California Irrigation Management Information System (CIMIS) from the Lodi Station (042) and <br />Lodi West Station (166). The estimate first determines whether the average monthly precipitation <br />exceeds average monthly evapotranspiration (ET). If so, then the difference is potential rainfall <br />recharge. This method does not consider runoff, although due to the relatively flat nature of the <br />site, runoff should be minimal. In February 2020, the EHD approved an adjustment to the <br />evapotranspiration (ET) rate based on net rainfall recharge calculation utilizing University of <br />California (UC) plant factors (PF) for established landscape plants. Terracon calculated the ET <br />adjustment factor (actual ET) based on the anticipated commercial landscape. Refer to Appendix <br />F Water Balance Recharge Analysis for monthly precipitation and ET averages. <br />Table 10. <br />Net Rainfall Recharge <br />CIMIS Station <br />Number / Location <br />Average Precipitation <br />(in/year) <br />Potential ETO <br />(in/year) <br />ET <br />Adjustment <br />Factor <br />Actual ET <br />(in/month) <br />Net Rainfall <br />Recharge <br />(in/year) <br />042/Lodi <br />166 Lodi West 15.46 50.50 0.51 25.76 7.54 <br />Based on this method, the average net rainfall recharge for Lodi is estimated to be 7.54 <br />inches/year. <br />The nitrate concentration of rainfall is estimated to be 1 mg/L-N (Hantzsche and Finnemore, <br />1992). <br />2.3.3 Current On-Site Sources of Nitrate <br />The current on-site sources of nitrate include natural processes and the existing septic systems. <br />2.3.4 Future On-Site Sources of Nitrate <br />Future on-site sources of nitrate include the existing septic systems, proposed septic system, <br />and natural processes.