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• Groundwater Extraction Well Installation Summary Report Page 3 The Southland Corporation 455 Grant line Road Tracy California December 6, 1996 relative to top-of-well-casing to determine the static water level Approximately 60 gallons of groundwater was purged from each well and stored In 55-gallon DOT-approved drums to be pumped through the groundwater treatment system The top of casing and rim of each new well box and the other 12 wells were surveyed by Schack and Company, Inc for horizontal position and elevation relative to meat}sea level datum using the top of the fire hydrant at the southwest corner of Grant Line Road and Parker Avenue per the City of Tracy datum (Appendix D) 50 TRENCHING & EXTRACTION LINE INSTALLATION On October 28 through November 7, 1996, Kvaener Davy Aronson Engineering Inc (Aronson) excavated two trenches,set five well vaults, and extended the existing east-west running soil vapor extraction (SVE) and groundwater extraction (GWE) lines southward to the new vaults and wells (Figure 2) Three-foot-square by 3-foot-deep traffic-rated street vaults were installed to protect the two groundwater extraction wells, and at three other locations along the two 3-foot-deep trenches for installation of possible future SVE and GWE wells The following schedule 40 PVC lines were stubbed up into the five vaults at the site Line Diameter Description 2-inch Groundwater Extraction Line 1-inch Groundwater Pump Control Conduit 1-inch Groundwater Pump Power Conduit 2-inch Soil Vapor Extraction Line 2-inch Lateral Slotted Shallow Soil Vapor Extraction Line The two 2-inch-diameter pipes 1n each trench were coupled into the existing SVE and GWE lines The piping in the trench was laid on and covered with approximately 6 inches of gravel, followed by self-compacting sand slurry to approximately 6 inches below grade, followed by base course gravel and hot patch asphalt to match the existing grade The bottom of each vault was sealed with hydrated bentonite chips and Portland cement to approximately 2 to 2 5 feet BGS A sketch of the piping layout and cross section of the trench is included with the field notes in Appendix C 5 1 Soil Sampling and Field Observations Soil samples were collected at four locations S1, S2, S3, and S4, during trenching activities at depths of 1 and 5 feet BGS (Figure 2) The shallow soil samples were collected directly from the backhoe bucket by driving a 2-inch-diameter by 6-inch-long brass tube into a freshly exposed soil surface The deeper sal samples were collected from a hand auger hole using an impact sampler with a single 0231INST RPT(Stitt 5 1) FLUOR DANIEL GTI �5_