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V GeotagicafTechnics inc. -.0w Page 3 C& B Equipment Additional Site Characterization Work Plan Project No. 336.2 July 15, 1996 ,.. A blank will be collected prior to sampling by filling the decontaminated sample chamber with water (provided by the laboratory) and then filling a VOA vial (provided by the laboratory) using the same procedures for actual sample collection. ` Equipment blanks for each sample, along with a field blank (prepared from water provided by the laboratory poured into a VOA vial on site), will accompany the samples to the laboratory and serve as checks against cross contamination. V A chain of custody document, listing all samples collected, accompanies the samples from field to laboratory, thereby providing a means to track their movement and insure their ` integrity. 2.3 Monitoring Well Installation ` We propose to install one monitoring well screened through the water table (MW-4) in order to define the lateral extent of the plume in the predominant downgradient direction from the point of release and to allow the detection of free phase floating product if present. The �- location and any modifications in well construction will be confirmed by reviewing data generated by the discrete groundwater sample analysis data from the four perimeter boreholes. It is expected that the well will not be installed during the initial mobilization. The well boring will be drilled using a 8.0 inch outside diameter continuous flight hollow stem auger owned and operated by a licensed well drilling contractor_ Soil cuttings will be added to the existing spoils pile stored on site until their disposition can be determined. MW-4 will be constructed using 2.0 inch diameter schedule 40 PVC casing with flush threads. A 15 foot screened interval will extend from 5 feet to 20 feet below surface grade ,.. (Figure 3 Well Construction Schematic). A#3 sand filter pack will surround and extend two feet above the 0.020" screened interval. A granular bentonite transition seal will be installed and hydrated. A surface seal will be achieved by pumping a neat cement grout (augmented with < 4% bentonite) via a tremie tube. The well will be secured with a locking watertight ` cap encased in flush mounted traffic rated well box. After the well sealing materials have set (>24 hours) the well will be developed (using �- mechanical surging and pumping methods) until a clear stream of water is obtained. The well will be purged and groundwater samples collected no sooner than 24 hours after well development. All development and purge water will be containerized in 55 gallon DOT approved drums and stored on site until their disposition can be arranged. 3.0 VERTICAL DEFINITION OF THE GROUNDWATER PLUME The following work is proposed to define the vertical extent of the groundwater plume at C & B Equipment. Except where noted all drilling and sampling will be conducted as per the �- Geological Technics Inc. June 15, 1996 Monitoring Well Installation and Groundwater Monitoring Work Plan.. 3.1 Well Location We propose to install one deep, discretely screened monitoring well (MW-101) north of the point of release. This location was selected based on its proximity to the point of release