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' Gado icalTerinc. g Page 5 Sinclair Trucking Project No.: 1030.2 August 11,2005 2.4 Decommission Monitoring Well Monitoring well MW-1 was decommissioned prior to performing excavation activities. ' V&W Drilling, a competent C-57 well driller, mobilized to the 5T site on February 7, 2005 to decommission MW-1 by over drilling the well casing. MW-1 was over drilled using 8- inch hollow stem augers guided down the center of the well casing via a guide rod attachment to the drill bit. Permits were secured and the local regulatory agency was notified 48 hours prior to commencing work. ' Grout, a cement-bentonite mixture, was used to seal the borehole. Bridging was avoided and a good seal achieved keeping the grout under pressure through a tremie pipe to feed grout into the borehole. The tremie pipe was submerged several feet below the level of grout at all ' times. The borehole was grouted to within five feet of the surface and the uppermost few feet was left open. A steel drum was placed over the borehole for security. ' Approximately 13 gallons of grout was required for the decommissioning of MW-1. The grout material will be allowed to dry for no less than 72-hours prior to any excavation ' activities taking place. 2.5 Excavation A professional geologist under the supervision of a licensed registered geologist at Geological Technics inc. supervised excavation oversight and monitoring for consistency ' with the Remedial Action Work Plan dated September 20, 2004. 2.5.1 Excavation Extent t An area of approximately 1,360 square feet was opened during the soil excavation activities. Five to six feet of clean overburden was stockpiled near the southeastern portion of the property. The remaining contaminated soil was excavated to a depth of approximately 13.5 ' feet below grade. Approximately 400 cubic yards of contaminated soil was excavated and stockpiled in a staging area in the northeastern portion of the property. ' Figure 2 shows the extent of the excavation in plan view. 2.5.2 Storm Water Management ' The excavation activities took place during good weather conditions. Storm water management and controls were available on-site but not required to complete site activities. ' 2.5.3 Stockpile Clean Overburden Clean overburden was temporarily stockpiled along the southeastern edge of the property -- until the excavation was completed (Figure 3). The stockpile was placed on an impermeable ' liner, covered and secured. Soil stockpile covers were secured so that they would not be blown off by wind and protect soil from possible precipitation.