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r.. Work Plan for Refined Plume Definition and Managemenl of Floating Product-7500 W Illh St., Tracy, CA. Page 56 �,. ASTM Standard D2922 (American Society for Testing and Materials 2001). At the time that the cut-off trench is backfilled, the top of the 6-in. diameter well-casing installed at one end of the trench will be capped by a casing closure. When the backfilling is complete, a flush-mounted heavy-duty well-head box will be installed to permit future access to the well casing for the purpose of extracting additional volumes of contaminated t.. groundwater, should such extraction become necessary. 9.4.1.8 Schedule It is estimated that it will take approximately one month from the time the project is authorized to prepare a final design and obtain an encroachment permit from the SJCPWD .� for installation of a cut-off trench in the shoulder of West Eleventh Street and.to obtain the necessary bonds for the trench construction that will also be required by that agency. We expect the remediation contractor to be able to open and, as necessary, shore the cut-off trench in two days. This will permit the first round of high-volume floating product extraction on the next day. It is the planned to maintain the trench open for two weeks during +�- which time a second round of floating product extraction will be scheduled. During that same two-week period, excavated, contaminated soil will be shipped off site to a Class II landfill. When floating product extraction is complete, it will require a maximum of two days to y� partially backfill the trench with crushed rock, place the geotextile membrane, install a well casing and well head vault, place compacted, clean native soil to complete the trench backfilling and to surface the area with crushed rock. When the trench backfilling is in place, the floating product remediation program will be complete. Based on the assumptions stated above, that is estimated to occur within 60 days of authorization for the work to proceed. Although the backfilling of the cut-off trench will complete its primary role as a floating product remediation system, the well casing installed into the crushed rock in the trench will remain open for at least one year so that, if appropriate, the casing can be available for high- volume extraction of contaminated groundwater. Regardless of when the cut-off trench system is closed, a report on the operation can be included in the next following report of groundwater-quality monitoring issued for the site. That should occur no more than 60 days after closure of the cut-off trench. Final closure off the cut-off trench system by grouting the well casing, excavating the well head vault and restoring the ground surface can be completed in one day and a system closure report included in the next following groundwater-quality monitoring report . sic