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Report- Monitoring V�ell Abandonment Page 3 Former Nelson Ready Mix GPE Project No. 518.2 October 30, 2007 2.0 Well Abandonment The following sub-sections describe the work' completed to properly abandon the groundwater monitoring wells. 2.1 Preparatory Work An application for a permit to abandon the wells and a Work Plan describing the field procedures was submitted to the SJC-EHD on October 5, 2007. The Work Plan was approved and the permit was issued. The SJC=EHD was notified that the final well abandonment was scheduled for October 29, 2007. During the time since the last sampling event, the current site owner constructed a large, (72,000 square foot) industrial building on the site. The concrete slab.of the floor encompasses all three monitoring wells. The construction company located two of the wells, MW-2 and MW-3, and the well boxes were re-set into the concrete slab of the floor. One well, MW-1, was not identified by the construction company, and the slab was constructed over the well leaving it inaccessible. In the fourth week of October, the well was relocated by use,of the original well survey, and the construction contractor saw-cut a hole through the pad. A backhoe was then used to re-expose the monitoring well, whereupon it was evident that the well box had been removed during the site leveling process. The well itself remained intact, however. The building construction.contractor requested that the original well boxes for MW-2 and MW-3 be left in place to minimize the damage to the floor. 2.2 Pressure Grouting On October 29, 2007, V&W Drilling (C-57 # 720904) mobilized to the site for the purpose of abandoning the wells. The following steps tasks were performed to complete the well abandonment by pressure-grouting. The well boxes lids were opened and removed (except for MW-1), as were the locking caps and locks. The dedicated tubing was removed from,each well. During the tubing removal, it was noted that at least two feet of fill was in the casing of MW-1. This was attributed to loose soil falling in during the building construction process. V&W Drilling personnel prepared neat cement for use as grout. Each well was sequentially fitted with a 2-inch pressure cap. Neat cement was then pumped into each well using a pneumatically actuated grout pump and a tremie pipe. Pumping continued until a positive pressure of at least 5 pounds per square inch was reached at each wellhead. The volume of each 20-foot long, 2-inch diameter, well casing was calculated at 3.2 gallons. The volume of grout pumped was monitored to verify that i 2937 Veneman Avenue, Suite B240 Geo-Phase Environmental Inc. Phone: (209) 569-0293 Modesto, Ca 95356 Fax: (209) 569-0295 �I