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' 3. VERTICAL CHARACTERIZATION OF GROUNDWATER ' In order to vertically assess hydrocarbons in groundwater, a deep offsite well is proposed for installation The location of the proposed well is shown on Figure 12 This location is located offsite and downgradient of the former underground storage tanks The scope of work for the ' installation of the deep groundwater monitoring well is presented below 3.1 PRE-FIELD ACTIVITIES Prior to field work a permit for the installation of one deep gr oundwater monitoring well (MW14) will be acquired from the SJCEHD ETIC personnel will acquire offsite access from the property owner, appropriately mark the proposed well location as indicated in Figure 12, and Underground Service Alert will be contacted at least 72 hours prior to drilling A licensed utility line locator will be subcontracted by ETIC to clear the marked well location for drilling If the marked well location is over or adjacent to a utility line, ETIC personnel will mark another appropriate location, which will be screened by the utility line locator to clear the location for drilling 3.2 WELL INSTALLATION Proposed well MW14 will be constructed as a 2-inch-diameter groundwater monitoring well across a deeper permeable zone The proposed location as presented in Figure 12 was selected to assess the vertical extent of impacted groundwater downgradient of the former tank field lie Currently the greatest depth explored at the site is 51 feet bgs in well SW2 The construction of proposed well MW14 will be based on the additional hydrogeologic and lithologic information acquired while drilling to depths greater than 50 feet bgs Drilling will be terminated at a depth of 70 feet bgs if no second permeable zone is encountered The ultimate depth of MW14 will be dependent upon the subsurface hthology encountered below 50 feet bgs Soil samples will be screened visually and with an organic vapor meter for evidence of petroleum hydrocarbons If petroleum hydrocarbons are observed and/or detected, a conductor casing may be set to a depth of 50 feet bgs Soil samples will be collected at 5-foot intervals to 45 feet bgs and continuously from 45 feet bgs to the total depth of the borehole in order to examine the lithology and to locate the base of the upper confining layer, and the next permeable zone The anticipated depth of the bottom of the upper confining layer and next permeable zone below 50 feet bgs is unknown Once the base of the upper confining layer is encountered, the boring will be drilled further to a second permeable zone If a second permeable zone 1s encountered before 70 feet bgs, 5 to 10 feet of screen will be set in place and the monitoring well installation will be completed If a second permeable zone is not encountered, then a well screened from 65 to 70 feet bgs will be installed Details concerning ETIC field protocol for conductor casing and well installation are presented in Appendix H 3.3 WELL DEVELOPMENT AND SAMPLING Prior to collecting groundwater samples, the well will be property developed Development will i occur either prior to establishing the bentonite seal during well construction, or 72 hours after GSProjects1739421MAS7ER\WP1WPO3031WPtx da 1 1