Demolition of Building A, the final building structure to be demolished, began last week and is approximately 50% complete. Building E demolition is complete and placement of liner over the slab is nearly complete. For a summer demolition update, see Demo Progress 24JUN – 7 JUL 2016.
Buildings B, B4, C and D have been completely demolished. The liner has been placed over the former Building D location and demolition continues towards the south end of Building C. The demolition crews have removed about half of Building E and are continuing demolition this week. Building A will be the final building removed. For more photos on demolition, see NTCRA Progress.
Building demolition continues onsite with Building D demo nearly complete. The crew will be approaching Building C demo this week and the liner/cover crew will be mobilizing next week. April progress can be viewed on this slideshow.
A burn bar, or thermal lance, heats and melts steel in the presence of pressurized oxygen to create very high temperatures to cut large pieces of machinery. On site, the burn bar was used for size reduction for the pressure tank and 1,400 ton press as seen in the Burn Bar 2016 movie.
Currently, we are completing a “sub-slab investigation” program, which involves drilling holes through the concrete floor slabs, and then collecting soil samples below the buildings. This information will be used to refine the scope and estimated cost for the next phase of work. The next phase of work will be the “Remedial Action,” during which the slabs and impacted sub-slab soils will be removed.
Our demolition contractor, Charter, is expected to re-mobilize to the site in late March 2016 to perform the final utility decommissioning and other preparations prior to building demolition. Building demolition is planned to commence in mid-April 2016, and is expected to continue through August 2016. After demolition is complete, the building foundations will remain in place and an impermeable cap will be installed to minimize water infiltration until the Remedial Action. To see the progress photos of the buildings ready for demolition, see NTCRA Progress.
Once building demolition activities are in full swing, up to 12 trucks will leave the site daily. Work is planned for weekdays, with truck traffic scheduled between 9:30 AM – 3:30 PM, to avoid rush hours and the period when school buses are active.
Fall and winter RI/FS activities included the installation and sampling of 25 groundwater monitoring wells to further delineate the 1,4-dioxane plume associated with the site. de maximis and its subcontractor, Geosyntec, met with representatives of EPA, MassDEP and the community groups in December 2015 to discuss the investigation results and next steps. Three additional monitoring wells were installed in January 2016, as shown on the figures illustrating the locations of and monitoring data for the investigations (NMI GW Figures).
Since January, the technical team has been working with EPA, MassDEP and the Acton Water District to design and implement a “shutdown test” of the Assabet 1A and 1B production wells. This test is planned to start the week of March 14. The resulting data will help to define the “capture zone” of the Assabet wells, which will assist in the selection of an effective location to install and test a pumping well. That test data will be a key component for the design of the system that will be installed to cut off the flow of contamination from NMI. In summary, solid progress has been made to collect the data necessary to design the Groundwater Non-Time-Critical Removal Action (NTCRA) selected by EPA in September 2015 as part of the necessary remediation for the site.
By the end of 2015, all Depleted Uranium, corrosive mixed wastes, mixed waste organics, mixed waste metals, Sonedyne wastes, equipment oils and pit sludges previously stored on site during the NTCRA were all shipped off-site for disposal with EnergySolutions.
Stage 1 of the building demolition began this fall as part of the Phase 3 Construction Submittal and is now complete, including demolition of Butler buildings B1, B2, and B3, Tank House, pump house 2, acetone shed, hydrogen peroxide shed, gas cylinder shed, and exterior compaction dumpster. The remaining slabs are being placed under temporary cover for the winter. For more demolition photos, see NTCRA Progress.
EPA provided a news release 1OCT2015 announcing the completed Record of Decision (ROD) for the Nuclear Metals Site, Inc. The ROD generally includes the following components:
• Excavation and off-site disposal of approximately 82,500 cubic yards of contaminated materials.
• In-Situ stabilization of depleted uranium contaminated soils in the Holding Basin using apatite injection.
• Extraction and ex-situ treatment of groundwater for volatile organic compounds (VOCs) and 1,4-dioxane.
• In-situ treatment of depleted uranium and natural uranium in groundwater.
• Long-term monitoring to monitor the effectiveness of in- and ex-situ treatment.
• Institutional Controls to prevent disturbance of the Holding Basin area, prevent the use of Site groundwater, and address potential vapor intrusion risks.
Last updated on October 2, 2015