Laserfiche WebLink
Soil Suitability/ Nitrate Loading Study Irerracon <br /> Souza Property - Tracy, CA <br /> February 28, 2020 Terracon Project No. NA207011 <br /> 2.2 Groundwater Analysis <br /> 2.2.1 Regional Groundwater <br /> A discussion of regional groundwater, including depth to groundwater is included in Section 1.4.1. <br /> No significant seasonal trends were evident from the sources consulted. <br /> 2.2.2 Potential Ground Water Contamination Issues <br /> A discussion of issues related to potential groundwater contamination is included in Section 1.4.2. <br /> 2.2.3 Current and Future On-Site Ground Water Uses <br /> A domestic groundwater well is not currently located on the site. <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 (ETo) data was obtained from the <br /> California Irrigation Management Information System (CIMIS) from the Tracy (167) station. The <br /> estimate first determines whether the average monthly precipitation exceeds average monthly <br /> evapotranspiration (ET). If so,then the difference is potential rainfall recharge. This method does <br /> not consider runoff, although due to the relatively flat nature of the site, runoff should be minimal. <br /> Terracon additionally calculated an ET adjustment factor (actual ET) based on the anticipated <br /> residential landscape. Refer Appendix F Water Balance Recharge Analysis for monthly <br /> precipitation and ET averages. <br /> Table 10. <br /> Net Rainfall Recharge <br /> CIMIS Station Average Potential ET Actual ET Net Rainfall <br /> Number/ Precipitation ETO Adjustment (in/year) Recharge <br /> Location (in/year) (in/year) Factor (in/year) <br /> 167/Tracy 8.36 60.48 0.55 33.26 2.33 <br /> Based on this method, the average net rainfall recharge for the Tracy is estimated to be 2.33 <br /> inches/year. <br /> Responsive■ Resourceful ■ Reliable 13 <br />