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Soil Suitability/ Nitrate Loading Study <br /> Ripon Winery Proposed Warehouse ■ Ripon, CA 1 rerracon <br /> January 20, 2017 ■ Terracon Project No. NA167059 <br /> 2.3 Sources and Impact of Nitrate to Groundwater <br /> 2.3.1 Current Off-Site Sources of Nitrate <br /> Septic systems, agriculture, and dairies in the area may be the most significant sources of nitrate <br /> in groundwater. Septic tank use in the vicinity is discussed in Section 1.3.4. <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 /> The estimate of deep percolation of rain is based on the average monthly precipitation of rain fall <br /> and evapotranspiration for Manteca, California. The estimate first determines whether the <br /> average monthly precipitation exceeds average monthly potential evapotranspiration. If so, then <br /> the difference is potential deep percolation. This method does not consider runoff, although due <br /> relatively flat nature of the site runoff should be minimal. Average potential evapotranspiration <br /> was obtained from the California Irrigation Management Information System (CIMIS). Refer to <br /> Appendix E fob the data and calculation. <br /> __ — <br /> Table 6. <br /> Estimate of Deep Percolation of Rain for the Site <br /> Location Deep Percolation of Rain <br /> Manteca 3.54 inches per year <br /> Based on this method, the average deep percolation of rain for the Manteca area is estimated to <br /> be 3.54 inches/year. The nitrate concentration of rainfall is estimated to be 1 mg/L-N (Hantzsche <br /> and Finnemore, 1992). <br /> 2.3.3 Current On-Site Sources of Nitrate <br /> The current on-site sources of nitrate include natural processes. <br /> 2.3.4 Future On-Site Sources of Nitrate <br /> Future on-site sources of nitrate are discussed in section 1.3.7. <br /> 2.3.4.1 Quantity and Quality of Wastewater from Project <br /> The following discussion is for determining the long-term wastewater flow generated from the <br /> proposed construction. We understand that the project will consist of an approximately 509,500 <br /> SF wariuing S) including a 6,000 SF office and restroom. The restroom will service <br /> a maxi of 30 per anent employees per day; with up to 16 vi�itors daily. We understand the <br /> facilityill a open 24 hours per day,five days per week year- nd. <br /> Responsive■ Resourceful ■ Reliable 13 <br />