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Geological red wks lne. Page 9 <br /> City of Escalon <br /> Project No.: 750.2 <br /> May 16,2005 <br /> 3.9 Stockpiled Soil <br /> No stockpiled soil relating to the former underground storage tanks is stored on this property. <br /> 3.10 Monitoring Wells <br /> Five (5) water table and one (1) deep monitoring well as well as four (4) vapor extraction <br /> wells are associated with this site and a well construction summary is included as Table 11. <br /> Upon issuance of a"No Further Action" letter from the CRWQCB, the monitoring and vapor <br /> extraction wells will be properly abandoned under a SJCEHD permit. <br /> Boring logs ndt used in generating this report may be found in: <br /> • GTI: Soil and Groundwater Investigation Report—March 15, 1999 <br /> • GTI: Additional Site Characterization Report—January 31, 2000 <br /> • GTI: Additional Site Characterization Report—January 30, 2001 <br /> r <br /> • GTI: Interim Soil Investigation Report —October 2, 2003 <br /> 3.11 Background Conditions <br /> A water quality degradation analysis is summarized below in accordance with § 2550.4(d) of <br /> Title 23, California Code of Regulations, Chapter 15: <br /> 1) Potential adverse effects on groundwater quality and beneficial uses: <br /> A. The constituents of concern and average concentrations at the COE site <br /> include: The quarterly groundwater monitoring events have revealed that all <br /> monitoring wells at the COE site have been non-detect above laboratory <br /> reporting limits for all analyzed constituents for the last nine monitoring <br /> events. <br /> B. Hydrogeological characteristics of the facility and surrounding land are <br /> relatively uniform; characterized by alternating layers of sand, silt, and sand- <br /> silt mixtures. The details are discussed in Section 2.0. <br /> C. Groundwater bearing and slope average N73°W at 0.0019 ft/ft as discussed in <br /> Subsection 2.3.2. Groundwater velocity is estimated to be 0.758 to 75.8 feet <br /> per year as discussed in Subsection 2.3.4. Vertical groundwater gradient is <br /> mostly in the negative direction (downward) at 0.0037 ft/ft, which is similar as <br /> the horizontal gradient. <br /> D. There are no groundwater users within a 1,600-foot radius of the COE site as <br /> discussed in Section 3.1. <br /> E. According to the USDA Soil Survey of San Joaquin County, California <br /> (McElhiney, M. A., 1992); the soils below the site are very deep, somewhat <br /> excessively drained, nearly level soil on dunes with 0 to 2 percent slopes. The <br /> details are discussed in Subsection 2.2. It is not likely that potential future <br /> uses of groundwater in the area will be impacted. <br /> V <br /> V <br />