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Bird Road Facility Page 9 of 13 Project Number: E07183A November 30, 2007 _ II.2.3 Current and Future On-Site Ground Water Uses There is currently one well on site, as noted in Section I.4.3. Ground water will be developed and used on the site for the commercial property. II.3 Sources and Impact of Nitrate to Groundwater II.3.1 Current Off-Site Sources of Nitrate Septic systems, agriculture, and dairies in the area may be the most significant sources of nitrate in ground water. Septic tank use in the vicinity is discussed in Section I.3.4. II.3.2 Contribution of Rainfall An estimate of the quantity and quality of rainfall was required for the nitrate loading analysis. The estimate of deep percolation of rain is based on the average monthly precipitation of rain fall and evapotranspiration for Tracy, California The estimate first determines whether the average monthly precipitation exceeds average monthly potential evapotranspiration. If so, then the difference is potential deep percolation. This method does not consider runoff. See Plate 9 for the data and calculation. Average potential evapotranspiration was obtained from the California Irrigation Management Information System (CIMIS). Tracy is located within evapotranspiration zone number 12. Average rainfall was obtained from the Western Regional Climate Center (Station 048558). Based on this method, the average deep percolation of rain for the Tracy area is estimated to be 2.52 inches. The nitrate concentration of rainfall was estimated to be 1 mg/L-N (Hantzsche and Finnemore, 1992). II.3.3 Current On-Site Sources of Nitrate The are no current on-site sources of nitrate except for the existing septic system and natural processes. II.3.4 Future On-Site Sources of Nitrate 11.3.4.1 Quantity and Qua/ity of Domestic Wastewater from Proposed Project The following discussion is for determining the long-term waste water flow generated from the proposed construction for the nitrate loading analysis and should not be used for septic system design purposes. Typically, use estimates for the sizing of septic systems include a peak use factor, whereas the numbers discussed here are based on long-term averages. We understand that the office is planned to be open approximately eight hours per day, five days per week. The truck wash and heavy equipment repair shop is proposed to have 12 employees and no customers. The Site will also have spaces available for four (4) trailers to be 902 Industrial Way•Lodi,CA 95240•209.367.3701 •Fax 209.369.4228 02007 Neil O.Anderson&Associates,Inc