The largest nuclear waste site in the country—and one of the largest environmental cleanups in the world—requires plenty of seemingly small-scale successes to move cleanup forward.

The Dept. of Energy Hanford Nuclear Waste Site in southeast Washington sits engaged in a multi-billion-dollar cleanup project that started in 1989, an effort to clean up 586 acres of radioactive contamination. Originally in use from 1943 to 1987 to produce plutonium used in nuclear weapon creation, the site was left with contaminated buildings, soil, groundwater and 53 million gallons of radioactive waste. The largest ongoing project at the site includes Bechtel’s creation of the Waste Treatment Plant (WTP), which will turn that 53 million gallons of waste into vitrified glass for long-term safe storage. To make it happen, the WTP requires a high-level waste facility, a low-activity waste facility, a pretreatment facility, laboratory and mix of auxiliary buildings.

While stuck in design issues—working with radioactive waste offers up new levels of safety standards—to get the project moving forward, it takes wins from engineers to make it happen. A recent victory came with the completion of testing of the pulse-jet mixer vessels and controls systems necessary to safely mix radioactive tank waste as it moves through the pretreatment facility. Michaela Trenidad led the testing program, a two-year, $80 million effort.

The testing and its results will inform the new design for the vessel, which will get used throughout the facility, a resolution to a key technical issue raised by the energy department.

“Addressing the technical questions surrounding pulse-jet mixers is an important accomplishment on the Pretreatment Facility,” says Bill Hamel, assistant manager for the WTP Project at the DOE’s Office of River Protection. “The collaboration among DOE and contractors over the four years of testing should be a model for how we do business.”

The test campaigns began in 2014 to study the mixers on a half-scale basis, then more recently moved to full-scale testing. Testing used non-radioactive materials that simulate and bound the range of expected waste stream conditions. The final test campaigns used a full-scale prototype of the vessel, testing both the controls and mixing performance.

“We have produced a result our customer can rely upon and move forward with confidence in the nuclear quality and safety of the Pretreatment Facility,” says Peggy McCullough, Bechtel National project director for the WTP.

Working in an integrated technical team with DOE, national labs, Bechtel, external experts and stakeholders to resolve issues and collectively bring forward the solution, Trenidad emphasized a collaborative mind set to ensure all parties moved toward a solution before testing could move forward, removing all unknowns. Overseeing more than 30 engineers, the cost and plans of the pulse-jet mixer vessel testing, she also had to manage many different professional inputs that came with working in the integrated team on a project never before faced.

Finding success in the pulse-jet mixer vessels offers up a path forward for one of the world’s largest environmental projects, a seemingly small win that plays out much larger in reality.

Follow Tim Newcomb on Twitter at @tdnewcomb.