ARCHIVED REPORTS_XR0013114 - Laserfiche WebLink

Home Browse Search

I Soils encountered during previous investigations consist primarily of interbedded sand, silty sand, sandy silt, silt, and clay to a total explored depth of 100 feet. Previous investigations have encountered groundwater . generally within a silty sand at approximately 22 to 27 feet below 'grade surface (ft bgs). During the August 2011 groundwater monitoring event, groundwater depths ranged from 22 to 24 ft bgs. 2.0 WELL DESTRUCTION ACTIVITIES 2.1 PREFIELD ACTIVITIES Prior to initiating any field activities, CRA obtained well destruction permits from the San Joaquin County Environmental Health Department (Appendix B). A site specific health and safety plan was prepared and reviewed by all appropriate personnel. All proposed well destruction locations were pre-marked. with white - paint and Underground Service Alert (USA) was notified to identify potential subsurface utilities in the area. Prior to well destruction activities, CRA also completed a utility survey using a private utility locator to confirm all USA,markings and locate any subsurface utilities not indentified by USA. i 2.2 WELL DESTRUCTION Cascade Drilling, LP (Cascade) of Rancho Cordova, California, destroyed all 22 wells at the site using the drill-out method. Wells were over-drilled using a truck mounted hollow-stem auger drill rig equipped with 8-inch, 10-inch, and 12-inch augers as determined by the diameter of the well. Well destruction activities took place from � July 23 through July 27, 2012. Wells MW-7, MW-2, and MW-10 were destroyed on i' July 23, 2012. Wells MW-3, MW-5, MW4, AS-1 and MW-1 were destroyed on July 24, j 2012. Wells MW-9, EW-1 and MW-15 were destroyed on July 25, 2012. Wells MW-8, MW-18, MW-14, MW-13, MW-11, MW-12, MW-16, MW-17, and MW-6 were abandoned on July 26, 2012. Wells MW-19 and MW-20 were destroyed on July 27,2012. Each well box was removed using a jack hammer and four borings were hand-angered to 5 feet below grade (fbg) around each well to ensure no subsurface utilities were present. The well casing and filter pack materials of each well was subsequently drilled out to total depth using a hollow stem auger equipped with a disposable drill bit. After well construction materials were removed, the remaining hole was backfilled with Portland Typel/11 cement grout and topped with 6 inches of concrete to match the 167556(15) 2 CONESTOGA-ROVERS$ASSOCIATES 1 14