Mangrum, 56, directs the world’s largest cleanup to date of polychlorinated biphenyls (PCBs). Advanced technology is driving much of the project. The vice president of remediation for Morris Plains, N.J.-based Tetra Tech EC Inc. recommended the use of computerized mapping, precision dredging and just-in-time processing to remove or cap off 3.8 million cu yd of PCB-polluted sediment along 13.3 miles of the Fox River in Green Bay, Wis.

The unique approach for the nine-year, $600-million job carefully maps out where the pockets of pollution sit and how deep they run, then uses contour-suction dredges to remove only the amount of sediment needed to capture the PCBs. The dredge works like a wood router with a vacuum hose: The rotating head mills away a specified amount of river-bottom silt, and the vacuum sucks it up.

Rather than just undercutting the contaminated sediment and dumping the bucket, the toxic material is sorted out from the clean stuff. After it is sucked up, the silt flows directly to a nearby processing plant, where the PCB-laden sediment is squeezed dry in some of the world’s largest filter presses. Water is filtered and returned to the river or reused in the processing plant. At places in the river where the polluted silt can’t be removed, the pockets are capped with sand and rock.

Mangrum’s method minimizes the amount of good silt that ends up in a landfill, reducing overall cost. “There’s no use in excavating, processing and landfilling more silt than necessary,” says Mangrum. It is expected to save about $100 million, compared to conventional dredging and landfilling techniques. The cost per cubic yard is about $160, including landfilling the dried contaminated sediment.

Tetra Tech expects the Fox River technique to be useful for cleaning up a variety of other chemicals that require dredge spoils to be managed as regulated waste, particularly where landfilling costs are high. It also could be beneficial for dredging harbors that have contaminants in their sediment.

A team-oriented leader, Mangrum is quick to give credit for the project’s early success to colleagues, subcontractors and suppliers. But this is clearly his project and a labor of love. The Louisiana native started out as a pulp-and-paper superintendent and, after cleaning up a variety of wastes, is now back in paper. At the Fox River, PCBs reach levels as high as 3,000 parts per million. The U.S. Environmental Protection Agency and the Wisconsin Dept. of Natural Resources (DNR) mandated the cleanup after identifying eight paper companies that had flushed 700,000 lb of PCBs into the river from the 1950s to the 1970s. Descendants of three companies are now paying for the Superfund project.

Waste-management expert Mangrum guides a landmark riverbed PCB cleanup using a unique combination of technologies that saves time and money.

Mangrum developed the new remediation concept based on his 28 years of experience in the waste-management profession and involvement in more than 400 cleanup projects throughout the continental U.S. He has guided the Fox River project daily, supervising the development of the system, selection of equipment, construction of the 247,800-sq-ft processing plant, hiring subcontractors and coordinating the project owners, Wisconsin DNR and federal EPA regulators.

Mangrum also is running the project in a way that is less disruptive to the river and the people who live in the area. The operation puts a high premium on cleanliness, noise reduction, minimizing interference with river activities and maximizing community education. So far, it has pumped about $200 million into the local economy. Over the project’s remaining eight years, Mangrum expects the work to feed another $100 million into the area.