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lrerracon Soil Suitability / Nitrate Loading Study <br />Azevedo Property Acampo, CA <br />June 19, 2019 Terracon Project No. NA197009 <br />2.3 Sources and Impact of Nitrate to Groundwater <br />2.3.1 Current Off-Site Sources of Nitrate <br />Agriculture and septic systems in the area may be the most significant sources of nitrate in <br />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 data was obtained from the California <br />Irrigation Management Information System (CIMIS) from the Acampo (042) and Acampo West <br />(166) stations. The estimate of deep percolation of rain is based on the average monthly <br />precipitation of rain fall and evapotranspiration for San Joaquin County, California. The estimate <br />first determines whether the average monthly precipitation exceeds average monthly potential <br />evapotranspiration. If so, then the difference is potential deep percolation. This method does not <br />consider runoff, although due relatively flat nature of the site runoff should be minimal. <br />Table 9. <br />Estimate of Deep Percolation of Rain <br />Location Average Deep Percolation of Rain <br />Acampo Area 4.49 inches per year <br />Based on this method, the average deep percolation of rain for San Joaquin County is estimated <br />to be 449 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 the current septic system, agricultural land use and <br />natural processes. <br />2.3.4 Future On-Site Sources of Nitrate <br />Future on-site sources of nitrate include the proposed septic system, existing septic sytem, and <br />natural processes. <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 development for the nitrate loading analysis and should not be used for septic system <br />Responsive Resourceful Reliable 14