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Ms. Pamela J. Martinez, et al. � <br /> October 24, 1994 Project 0805-117.01 <br /> Page 2 <br /> The vapor extraction well will be drilled using a truck-mounted drill rig with 8- to 10-inch-diameter <br /> augers. A 4-inch-diameter polyvinyl chloride casing will be installed in the boring. For safety and <br /> security reasons, the top of the casing will be fitted with a locking cap and an aluminum cover with <br /> specially designed fasteners. The aluminum cover will be set approximately 1/4-inch above surrounding <br /> grade. The boring will take approximately 3 hours to drill, and the vapor extraction well construction <br /> will take approximately 4 hours. <br /> EMCON anticipates the work will be completed in approximately 1 day. Two subcontractor personnel <br /> will operate the drill rig, and a geologist from EMCON will be present during drilling. Every effort will <br /> be made to keep the work area clean and to restore the area to its original condition when the work is <br /> completed. We rill contact you to coordinate drilling operations to determine which day of the week is <br /> most convenient. Our tentative schedule for the construction of the vapor extraction well is December <br /> 1994. Upon receipt of your authorization, we will schedule a date for our work and we will inform you <br /> of that date. <br /> Depending on the findings of this phase of the investigation, we may have to connect the well to a <br /> remediation system. The vapor extraction well would be used to remove hydrocarbons from soil by <br /> placing a vacuum on the well and drawing the hydrocarbon vapors through a pipeline to a remediation <br /> unit to be located on the ARCO site. To connect the well to a remediation unit at the ARCO station <br /> will require EMCON and its contractors to lay horizontal pipeline from the well to the station. A <br /> schematic of the piping design is shown on Figure 3. <br /> This work would take approximately 1 week to complete. If the well is connected to a remediation <br /> unit, an EMCON technician would periodically need to gain access to the well for data acquisition and <br /> maintenance for approximately 1 year, or as required until remediation is completed. After the soil is <br /> remediated and the well is no longer needed, the well will be properly destroyed by drilling it out with a <br /> 10- to 12-inch-diameter auger and backfilling the borehole with neat cement. The ground surface will <br /> then be restored to resemble the surrounding ground material A boring will be drilled adjacent to each <br /> well to collect soil samples to confirm that hydrocarbons have been removed from the soil; the borings <br /> will be backfilled with neat cement. <br /> EMCON would appreciate your cooperation in this matter. Please sign and return both copies to our <br /> office. We will forward both copies to ARCO. ARCO will then sign both copies and will return one <br /> copy to you for your files. Upon your authorization to access your property, we will arrange a time to <br /> perform the work and appraise you of the schedule. <br /> SAC/PJU0805\108051170.1 CM-94/mam:3 <br />