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14 . 14 <br /> URS <br /> Mr. Harlin Knoll <br /> September 20, 2005 <br /> Page 2 <br /> Utility Clearance <br /> Well locations will be clearly marked and Underground Service Alert (USA) will be notified a minimum <br /> of 48 hours prior to commencement of field activities. In addition, a private utility location company <br /> will survey the site for buried utilities, and the first 5-feet below ground surface (bgs) at each well <br /> location will be hand cleared with either an air or water knife to a diameter of 10 inches (monitoring <br /> wells ATR-1 through ATR-4 and ATR-8 through ATR-12, AS wells S-1 through S-3, and soil vapor <br /> extraction/AS wells VES-1 through VES-7) or 12 inches diameter (monitoring wells ATR-5 through <br /> ATR-7, and groundwater monitoring/AS well SMW-I) prior to abandonment activities. <br /> Well Abandonment Methods <br /> The 12 groundwater monitoring wells (ATR-1 through ATR-12), 3 air sparging (AS) wells (S-1 through <br /> S-3), 7 soil vapor extraction/AS wells (VES-1 through VES-7), and 1 groundwater monitoring/AS well <br /> (SMW-1) will be properly abandoned by a licensed drilling contractor under the direction of a URS <br /> geologist. The well locations are presented on Figure 2 and well construction details are presented in <br /> Table 1. <br /> Nine of the twelve monitoring wells (ATR-1 through ATR-4 and ATR-8 through ATR-12) will be <br /> abandoned by over-drilling with 10-inch diameter outside-diameter (OD) hollow-stem augers (HSAs) <br /> then filling the borehole from total depth to near ground surface with a Portland cement grout containing <br /> <5% bentonite powder. The remaining three monitoring wells (ATR-5 through ATR-7) will be <br /> abandoned by over-drilling with 12-inch OD hollow-stem augers then filling the borehole from total <br /> depth to near ground surface with a Portland cement grout containing <5% bentonite powder. Surface <br /> completions will consist of concrete that will be finished flush to the surrounding ground surface. <br /> The soil vapor extraction/air sparge wells (VES-1 through VES-7) and air sparge wells (S-1 through S3) <br /> will be will be abandoned by over-drilling with 10-inch diameter outside-diameter (OD) hollow-stem <br /> augers (HSAs) then filling the borehole from total depth to near ground surface with a Portland cement <br /> grout containing <5% bentonite powder. The associated horizontal piping will be filled with a Portland <br /> cement grout containing <5% bentonite powder. Surface completions will consist of concrete that will <br /> be finished flush to the surrounding ground surface. <br /> The groundwater monitoring/air sparge well (SMW-1) will be abandoned by over-drilling with 12-inch <br /> OD hollow-stem augers then filling the borehole from total depth to near ground surface with a Portland <br /> cement grout containing <5% bentonite powder. Surface completions will consist of concrete that will <br /> be finished flush to the surrounding ground surface. <br /> The only exception to the above well abandonment methods will be wells within 10-feet of the UST <br /> compound or located too close in proximity to product lines. If the above condition is found in the field <br /> (possible well locations are ATR-3, ATR-4, VES-5, and VES-6) the well will be abandoned by pressure <br /> grouting from total depth to near ground surface with a Portland cement grout containing <5% bentonite <br /> powder. Surface completions will consist of concrete that will be finished flush to the surrounding <br /> ground surface. <br /> K:1WprocessV5 BP ARCO%020931Well Destr12093 Well Destruction WP Addendum 05.doc <br />