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Soil Suitability/ Nitrate Loading Study Addendum lFerracon <br /> Arriaga Property Stockton, California <br /> August 31, 2020 Terracon Project No. NA207046 <br /> the anticipated residential landscape. Refer to Appendix F Water Balance Recharge Analysis for <br /> monthly precipitation and ET averages. <br /> Table 7. <br /> Net Rainfall Recharge <br /> CIMIS Station Average Potential ETO ET Actual ET Net Rainfall <br /> Number/ Precipitation Adjustment Recharge <br /> Location (in/year) (in/year) Factor tin/year) (in/year) <br /> 042/Lodi <br /> 070/Manteca 12.27 52.37 0.18 9.43 8.35 <br /> 248/Holt <br /> Based on this method, the average net rainfall recharge for Stockton is estimated to be 8.35 <br /> inches/year. <br /> As indicated in our prior 2019 NLS report (Terracon Project No. NA187059), the nitrate <br /> concentration of rainfall is estimated to be 1 mg/L-N (Hantzsche and Finnemore, 1992). <br /> 2.3.3 Current On-Site Sources of Nitrate <br /> As indicated in our prior 2019 NLS report (Terracon Project No. NA187059), the current on-site <br /> sources of nitrate include the existing residential septic system and natural processes. <br /> 2.3.4 Future On-Site Sources of Nitrate <br /> As indicated in our prior 2019 NLS report (Terracon Project No. NA187059), the site is proposed <br /> to be developed with an additional 960 SF mobile home south of the existing residence and <br /> existing septic system. Therefore, the future on-site sources of nitrate will include the existing <br /> residential septic system, the proposed residential septic system, and natural processes. <br /> 2.3.4.1 Quantity and Quality of Wastewater from Project- Revised <br /> As indicated in our prior 2019 NLS report (Terracon Project No. NA187059), the estimated <br /> potential average daily flow for the existing and proposed residence was 560-gallons of effluent <br /> per day based 70-gallons per person per day times two people per bedroom. <br /> In February 2020, the EHD approved a revised calculation method for long term average <br /> discharge of waste water and recommended 100 gallons for the first bedroom and 50 gallons for <br /> each additional bedroom. The following table presents the revised long term average discharge <br /> rate for the site. <br />» Responsive ■ Resourceful ■ Reliable 13 <br />