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12 February 2018 <br />AGE Project No. 95-0167 <br />Page 2 of 3 <br />AdvancedGeo <br />Environmental <br />'agsg <br />Four (4) soil-vapor extraction wells (VW-1, VW-2, OW-1, and OW-2). <br />Five (5) in-situ air sparging wells (IAS-1 through IAS-5). <br />One (1) groundwater extraction well and two (2) groundwater extraction <br />observation wells (EW-1, OB-1, and OB-2). <br />Two (2) semi-permanent soil-vapor wells (VP-1 and VP-2) <br />Well construction details are summarized in Table 1. <br />Additionally, 0.5-inch to 3.0-inch diameter underground PVC piping was installed <br />approximately 12-18 inches bsg for remediation activities. Two and three-inch diameter <br />piping is routed from wells VW-1, VW-2, OW-1, and OW-2 to an SVE manifold in the <br />location of the former remediation enclosure; 0.5-inch diameter piping is routed from wells <br />IAS-1 through IAS-5 to an IAS manifold in the location the former remediation enclosure. <br />Based on historical analytical data and site mitigation activities, AGE proposes to <br />over-drill all wells (MW-1 through MW-8, EW-1, VW-1, VW-2, OB-1, OB-2, OW-1, OW- <br />2, IAS-1 through IAS-5, VP-1 and VP-2). Further, AGE proposes to cap and abandon in- <br />place the underground remediation piping. <br />PROCEDURES <br />As required, a health and safety plan will be prepared in accordance with Occupational <br />Safety and Health Guidance Manual for Hazardous Waste Site Activities (National <br />Institute for Occupational Safety and Health Administration, U.S. Coast Guard and U.S. <br />Environmental Protection Agency, 1985). Prior to drilling activities, each proposed drilling <br />location will be clearly marked and utility clearance obtained through Underground <br />Service Alert. A well destruction boring permit will be obtained from SJCEHD and they <br />will be notified a minimum of 48-hours prior to performance of field activities. <br />Prior to destruction activities, all wells will be checked for total depth and integrity using a <br />Solinst water level meter. Any obstructions found in the well will be removed. <br />Wells MW-1 through MW-8, OB-1, OB-2, OW-1, OW-2, and IAS-1 through IAS-5 will be <br />drilled-out to one foot deeper than the total depth of the wells utilizing 8.25-inch diameter <br />hollow-stem augers; wells EW-1, VW-1, VW-2 will be drilled-out to one foot deeper than <br />the total depth of the wells utilizing 10.25-inch diameter hollow-stem augers; and wells <br />VP-1 and VP-2 will be drilled out to total depth using a 3-inch diameter hand-auger. All <br />original well construction materials will be removed (including well casing, screen, filter <br />pack, and annular seal) to ensure that no residual contamination is sealed within the <br />abandoned borehole nor a filter pack remaining to act as a vertical conduit. Remaining <br />boreholes will be backfilled to surface grade with neat cement and covered with concrete <br />or asphalt, depending on the surrounding surface material. Neat cement will also be used <br />to fill and plug the ends of the remediation piping.