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' Spanos Property Page 2 Our Project Number: LGS090501 January 30, 2009 hese processes would generally contribute to additional reduction of nitrate-nitrogen concentrations in ground water to the extent that the nitrate-nitrogen concentration of ground- water Flow from up-gradient areas is lower." The Hantzsche and Fennemore approach is "...a conservative (worst case) first approximation of ground-water nitrate-nitrogen concentration resulting-from the combined effect of on-site sewage disposal systems and precipitation. This (the equation and approach) is for estimation of long-term effect (i.e., over years) on ground-water quality, and is not intended for prediction of seasonal changes" (Hantzsche and Finnemore, 1992). ' The method takes into account the development area, soil denitrification factor, rainfall volume, rainfall nitrate concentration, waste effluent quantity, and waste effluent nitrate concentration. The formula, assumptions and calculations used for_the analysis are shown on Plates 1 and 2. The units of nitrate used in the mass balance equation are nitrate-N, whose maximum drinking water contaminant level is 10 mg/L. - /1.0 CHEMICAL AND PHYSICAL PROPERTIES OF SOIL /I-I Chemical and Physical Soil Properties For a discussion of on-site-soil properties, refer to Section 5 of the SSS completed by Dillon & Murphy. 0.2 Mass Transport Soil Properties The percolation tests have revealed that the soils are-permeable to the maximum depth of exploration of 42-inches. These soils will allow moderately slow infiltration of water through the surface soils. Finer grain soils tend to slow the downward movement of percolating effluent from a septic system disposal field when compared to sandy soils. Due to the lack of sandy soils below the site, the potential impact to deep ground water is reduced when compared to other sites with thicker sections of sandy soil. The longer the effluent remains near the surface, the more treatment occurs due to natural processes within the soil. 2.0 GROUND WATER ANALYSIS /. 2.1 Regional Ground Water Regional ground water information, including depth to ground water and directional ground water gradient, is discussed in Section 4.1 of the SSS completed by Dillon & Murphy. s 2.2 Potential Ground Water Contamination Issues A discussion of issues related to potential ground water contamination is included in Section 4.2 of the SSS completed by Dillon & Murphy. 902 Industrial Way-Lodi,CA 95240-209.367.3701 -Fax 209.369.4228 ©2007 Neil O.Anderson&Associates,Inc