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Well Destruction Activities Groundwater monitoring wells MW-7, MW-8 and MW-9 will be destroyed by pressure grouting the casing and annulus to the total depth of each well. The sealing material will consist of neat cement with a 5% mixture of bentonite. The cement will be introduced with a tremie pipe extending to the bottom of each monitoring well:The three wells are 4-inch-diameter wells and range in depth from 74 to 79 feet. After the wells are grouted to a depth of approximately 3 feet below the ground surface, we will utilize a backhoe to remove the upper three feet of casing and the soil from an area 12 inches larger than the original 10-inch borehole. Once the soil has been removed, additional grout will be added to the casing and allowed to "mushroom" over the casing and into the surrounding three-foot- deep excavation. The excavation will then be backfilled with concrete to the ground surface. Black dye w' applied to the concrete at the ground surface in order to blend with the surrounding asphalt. 111 app e gr g p The excavated soil will be contained in labeled Department of Transportation-approved, 55-gallon drums and stored temporarily onsite until transportation to an appropriate disposal facility can be arranged. The three-foot sections of well casing will be placed in a waste receptacle. Report Preparation A Well Installation and Well Destruction Report will be prepared to transmit the field data. The Report will include(but.not be limited to)the following: Background summary, Scope of services performed, Observations during the field activities, Results of field activities, Confirmation numbers for GeoTracker submittals, - Vicinity Map and Site Plan indicating new and former well locations,and - Appendices including regulatory permits,boring/well logs and well survey data. Caltrans will be provided with a draft report, and upon receipt and incorporation of Caltrans' comments,we will provide three hard copies and one electronic (CD)copy of the finalized report. Stockton Yard Maintenance Station,Task Order No.45 Caltrans Contract 06A1141,EA 10-ON8300 Project No.59200-06-45 -4 - June 26,2008