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1 <br /> C7eotagual Ter faa Im Page 3 <br /> Groundwater Momtonng Report <br /> Project No 989 2 <br /> October 4,2004 <br /> ' not feasible This unit is not assigned a capability classification or a vegetative <br /> soil group <br /> ' 1.3 Site-Specific Hydrogeology <br /> A site map showing the locations of streets, structures, wells, and other site-related details is <br /> ' attached as Figure 2 <br /> ' 1.3.1 Lithology and Soil Characteristics <br /> The lithology of the site can be divided into 3 generalized sections, from the surface to 23- <br /> feet bgs, is primarily comprised of brown clays and silty-clay mixtures, from 23- to 31-feet <br /> bgs, is primarily comprised of brown sandy-clay, from 31- to 42-feet bgs, is comprised of a <br /> dense, plastic, "blue-grey" clay The Site Conceptual Model dated December 17, 2003 <br /> discusses the lithology and site characteristics in more detail <br /> 1.3.2 Groundwater Gradient and Bearing <br /> On July 15, 2004, the depth to groundwater was measured in all of the wells prior to purging. <br /> The average depth to water was 8 33 feet below the top of casing and the average <br /> groundwater elevation at the site is 128 feet below mean sea level The wells are screened at <br /> 5 feet bgs and groundwater surface continues to be below the tops of the screens in the nine <br /> shallow monitoring wells <br /> ' Site-specific groundwater gradient was calculated using MW-3,MW-7 and MW-9, and found <br /> to be N44°W at 0 0059 ft/ft A groundwater elevation map is included as Figure 3. Previous <br /> groundwater gradient calculations show a consistent bearing of north-northwest, averaging <br /> ' N30°W at 0 0065 ft/ft A Rose Diagram is attached as Figure 4 <br /> Vertical groundwater gradients were calculated for the site using the MW-1/MW-101 well <br /> ' pair and found to be negative The site-specific vertical groundwater gradient is -0 0152 ft/ft <br /> The vertical groundwater gradients are generally one order of magnitude greater than the <br /> horizontal groundwater gradients MW-1 is screened from 5 to 25 feet bgs and MW-101 is <br /> ' screened from 29 5 to 42 feet bgs Vertical groundwater gradient calculations have been <br /> performed at regular intervals since the installation of MW-101 on July 30, 2002 <br /> ' Historical groundwater bearing and slope are summarized in Table 1 and a summary of <br /> vertical groundwater is included as Table 2 of Appendix A <br /> ' As required under AB2886, the depth to groundwater data was submitted electronically to <br /> GeoTracker on September 7, 2004, with confirmation number 8136234879 <br /> 1 <br />` i <br />