ARCHIVED REPORTS - GROUNDWATER MONITORING WELL INSTALLATION AND LIMITED SOIL SAMPLING

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' hn KLEINFELDER Portion comer of the site. The location of MW-3 was also proposed to be the upgradient monitoring point. ' Following completion of drilling the soil borings, a 2-inch diameter PVC well was installed in each ' of the borings. The soil borings were advanced approximately 10 feet into groundwater. The wells were constructed with Schedule 40 PVC,. a 10 foot long 0.010 inch slotted screened section, and surrounded by and covered by a clean sand filter pack. The filter pack was surged using a surge ' block to settle the filter pack during well installation. An approximate 3 foot thick bentonite transition seal was installed above the filter pack. The remainder of the annular space was grouted to the surface with a neat cement grout material in accordance with San Joaquin County EHD ' requirements of using neat cement with no more than 3-5% bentonite powder added to account for the heat of hydration of the cement to limit the occurrence of damaging the well PVC casing. The wells were finished with a locking pressure cap with the well casing extending to the ground surface within a flush style well vault. See the Soil Boring Logs in Appendix B for the graphical presentation of the monitoring well construction, and the following table for a tabularized summary ' of the monitoring well construction. Text Table 2 ' Monitoring Well Construction Monitoring Total Depth Screened Filter Pack Bentonite Seal Grout Seal Well ...(feet) Interval(feet) Interval(feet) (feet)Desi nation ) (feet) MW-1 40 25 to 40 23 to 40 20 to 23 0 to 20 ' MW-2 40 25 to 40 23 to 40 20 to 23 0 to 20 MW-3 40 25 to 40 23 to 40 20 to 23 0 to 20 Note:All measurements are made relative to the ground surface at the time of drilling. ' Once the monitoring wells were installed, the top of each well was surveyed (by Morrow Surveying of Sacramento, California) so that depth to groundwater measurements in the wells could be converted to groundwater elevations to be used to assess groundwater flow direction and gradient. The wells were surveyed relative to a local benchmark. The wells were surveyed as described in Appendix G Section G-3.4. The following table outlines the monitoring well ' elevations, as measured from the tops of the well casings. Text Table 3 Monitoring Well Elevations Location TOC Elevation feet,msl) MW-1 11.79 MW-2 12.16 ' MW-3 11.29 TOC=Top of well Casing msl=mean sea level 42162.E01 /ST04R854 Copyright 2004,Kleinfelder,Inc. Page 10 of 22 ' PYng July 1,2004