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CW(og&jITedut&slar. Page 3 +y Additional Site Characterization And 15'Quarter 2004 Groundwater Monitoring Project No.425.2 March 22,2004 Well o. ia. creen of Frans. ea rout ea _ - - - -sur ace _ - - - -sur ace 3T-2Y'___72_ -sur ace - . -su ace Groundwater was first encountered at approximately 14 feet bgs. A #3 sand filter pack �- surrounded and extended not less than one foot above the 0.020 inch screened interval and was topped by a two-foot bentonite chip transition seal installed on top of the filter pack. A surface seal was achieved by pumping a neat cement grout (augmented with <4% L. bentonite). The wells were surged using a clean surge block to achieve maximum filter pack density prior to installing the bentonite transition seal. The well was secured with a locking watertight cap encased in a flush mounted traffic rated well box. The boring logs (Appendix C) contain the details of construction. Soil cuttings and drilling decontamination water were placed in DOT-17 55-gallon drums and stored on site until their disposal can be arranged. 2.1.1. Soil Sampling Procedure Between September and October 2003, GTI collected soil samples and maintained a log from two of the soil borings (MW-201 and MW-106). The samples were gathered in 6.0- inch brass liners using a 2.0-inch modified California split spoon sampler. The middle 6.0- inch brass liner was selected for laboratory analyses. The ends were covered with Teflon sheets and sealed with plastic caps. The brass liners and plastic caps were washed with an +..• Alconox solution and double rinsed prior to use. The sampling technician wore disposable gloves while collecting all samples. �. Up to five soil samples from each boring were submitted for laboratory analysis and a screening process was used to gather information through field observations. The field screening included: • Sediment type, especially grain size and clay content • Moisture content �. 0 Visible evidence of contamination (i.e., color change due to reduction of iron or discoloration from hydrocarbons and other pollutants) • Odor (measured via OVM, a portable photo ionization detector that uses a 10.6 eV lamp to detect compounds with ionization potential below 10.6 eV). Details on the geology encountered during the well installation, as well as the field observations, are included in Section 3.2, Geology and Field Observations. See Appendix C, Boring Logs for more information. �- 2.1.2 Soil Laboratory Analyses The following summarizes the soil sample testing used for this phase of work. The soil samples collected on September 23 and October 21, 2003, were delivered to Sherwood Labs (California ELAP No. 1400), of Hilmar, California, for the following analyses: