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Fj Soil Suitability&Nitrate LoadingStudy Y Page 15 St. Patrick's Church,Escalon, CA Project No. 607.1 October 14, 2009 and Finnemore model is then used to estimate the nitrate concentration in - groundwater. The calculation worksheet(s) are in Appendix E. System Acres Daily Flow Effluent Denitrification Percolation N Cone. N . Factor d R Loading Existing Res. 22 200 GPD 44 m L 25% 2.86 in. 20 lbs Proposed Chapel 22 300 GPD 80 m L 25% 2.86 in. 55 lbs Proposed Large Sys. 22 4,835 GPD 57.8 m L 25% 2.86 in. 636 lbs The existing residential septic system is producing a total of 20 pounds per year of nitrate leaching to groundwater. The proposed dedicated chapel system will ' add an additional 55 pounds for a total of about 75 pounds of nitrate per year. When the site is entirely developed, the large septic system will add 636 pounds of nitrate, but the currently existing residential system will no longer be active. Neither the existing or proposed septic systems will result in nitrate F1 concentrations in excess of the MCL limit at the uppermost layer of groundwater as summarized below: System N as % of MCL Existing Res. 2F" � Proposed Chapel 46 SA►��e y 4 -Proposed Large Sys The future large system is estimated to result in nitrate loading to groundwater that will exceed the MCUlimit. This calculation does not, however, consider the dilution that occurs as newly introduced water mixes with the deeper roundwater. e ca culated groundwater concentrations offer a "worst case" estimate, which is unlikely to be representative of actual groundwater conditions. The nitrate introduced from the current and proposed systems will move through the groundwater as it flows. As the groundwater flows, the somewhat F, elevated concentration of nitrate at the groundwater surface that results from the on site septic systems will rapidly decrease through dispersion. It is unlikely that nitrate in excess of MCL limits will be detectable beyond_ .he_-dawn gradient. limits of the property.,-I-- _ - F P2937 Veneman Ave.,#B240 Geo-Phase Environmental Inc. Phone: (209) 569-0293 Modesto, CA 95356 Fax: (209) 569-0295 Fi .0