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A 32,635-square-foot administration building was built in 1990 to provide office space for hundreds of Weldon Spring, Missouri, Site Remedial Action Project workers. The structure was demolished during the 2012 fall season, when it was no longer needed to support U.S. Department of Energy Office of Legacy Management (LM) long-term surveillance and maintenance (LTS&M) activities. The building’s concrete foundation slab was left in place until a decision for its removal could be made and any disposal concerns could be addressed.

LM decided that the concrete slab should be removed and processed through a rock crusher to recycle it for reuse. On March 4, 2015, the work was awarded to Premier Demolition (the same subcontractor that had demolished the administration building and the old wastewater treatment plant). The subcontractor mobilized on March 19 and began excavating the slab March 23. The slab was surveyed to verify and document that radiation was below background levels and that there were no radiological contamination issues. The portable rock crusher (permitted according to Missouri State regulations) began operating on April 6.

Project specifications required controls ensuring that dust stay within a specific area, identified as the Fugitive Dust Boundary. Orange cones delineated the boundary, which was closely monitored by contractor personnel. The controls requirement (stricter than State regulations) was instituted to protect site visitors. Dust was suppressed with water spray, aided by prevailing rains in the days leading up to the operation. Dust monitoring was conducted at several locations, including the Interpretive Center, near the office buildings, and inside the construction area. Monitoring results showed that dust was not a concern at the Interpretive Center or near the office buildings. Dust levels inside the construction area occasionally showed short-term spikes. When spikes occurred, dust suppression methods were either increased or repositioned to return dust to an appropriate level. Workers were not exposed to dust levels exceeding the action level for a continuous 8-hour period.

Safety-yellow marking paint was identified on a small portion of concrete. The paint had been sampled during an environmental assessment, conducted prior to administration building demolition, and found to contain lead. LM contacted the Missouri Solid Waste Program regarding the regulatory requirements for managing this concrete portion. They responded that the area contained
de minimus lead quantities and could be run through the crusher with no additional management or disposal requirements. However, to ensure the lead-based paint would not be hazardous if inhaled, lead monitoring was conducted during the 3-day activity to remove, segregate, and crush lead-painted concrete items. All lead sample results were well below Occupational Safety and Health Administration regulatory requirements.

Noise-level monitoring was another project safety measure. Readings taken in and around the construction area, including the Interpretive Center, and near the office building, showed that activity noises traveling beyond the construction area were at acceptable levels. Levels near heavy equipment operating within the construction area required that workers use hearing protection.

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Workers put the rock crusher to further use by breaking down concrete from past projects, which had been stored at an onsite debris-storage pad. Between the administration building foundation slab and concrete from former projects, approximately 2,157 cubic yards of gravel were produced. The gravel was used to backfill the concrete slab removal area. A total of 54,640 pounds of metal rebar, which was automatically separated from the concrete by the rock crushing machine, was sent offsite for recycling.

The administration building concrete-foundation removal project was completed April 22, on schedule and incident free.