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• • Mr. Ron Rowe <br /> Page 3 of 6 <br /> • C134) will be drilled to depths dictated by observations in the initial boring. The proposed <br /> locations of the borings are shown on Figure 2. <br /> If it appears appropriate based upon the CPT data, soil samples will be continuously collected <br /> in boring CB1. Soil samples will be collected at intervals of no less than five feet in borings <br /> CB2 through C134. Groundwater samples will be collected using discrete sampling equipment <br /> at predetermined intervals from CB1. Groundwater sampling intervals will be selected based <br /> upon the CPT data. <br /> Selected soil samples from each boring will be submitted to Argon Laboratory of Ceres, <br /> California for analysis of total petroleum hydrocarbons as gasoline (TPHg) using EPA Method <br /> 8015; for benzene, toluene, ethylbenzene, and total xylenes (BTEX) using EPA method 8020 <br /> and for oxygenated fuel additives and 1,2-DCA using EPA Method 8260. Certain soil <br /> samples, representative of significant lithologic units, will also be analyzed for porosity, <br /> hydraulic conductivity, grain size distribution, moisture content and organic carbon content. <br /> Soil samples selected for analysis will be from intervals previously determined to have been <br /> impacted by hydrocarbons, from intervals exhibiting field evidence of significant contamination, <br /> from high permeability zones and, in the deep boring, at least two consecutive depths beneath <br /> the termination of field evidence of contamination. All groundwater samples will be analyzed. <br /> • Based upon work recently conducted at 101 S. Wilson way it appears that direct-push <br /> drilling equipment may be capable of penetration to 100 feet of more. Should refusal be <br /> encountered at shallower depths, the borings will be advanced using hollow stem auger gear. <br /> All field work will be performed in accordance with Ground Zero's Quality <br /> Assurance/Quality Control Plan and the site-specific Health and Safety Plan on file with <br /> PHS/EHD. A drilling permit application and appropriate fees will be submitted following <br /> approval of this workplan addendum. <br /> TASK 3 ADDITIONAL MONITORING AND/OR VAPOR EXTRACTION <br /> WELLS <br /> Based upon the field and analytical data obtained from the confirmation borings, additional <br /> groundwater monitoring wells and/or vapor extraction wells may be proposed. <br /> The criteria for proposing additional vapor extraction wells will be the identification of <br /> significantly contaminated soil intervals which, due to lithology and depth, appear to be <br /> amenable to renewed soil vapor extraction. Screened intervals in vapor wells will be <br /> designed to encompass zones of significant contamination and higher permeability. <br /> • <br /> roek\closum\addendum <br />