Sludge cleanup creates park

With the help of civil and environmental engineers, lagoons that once stored wastewater sludge are now part of Wisconsin’s newest state park.

The lagoon system, constructed in the 1940s and located near Dane County’s Nine Springs E-Way, was designated in 1990 as a priority for cleanup because the sludge it stored contained high levels of polychlorinated biphenyls, or PCBs.

Engineering professor Tuncer Edil and his students worked with David Taylor from the Madison Metropolitan Sewerage District to devise an innovative method for capping the lagoon system. The engineers covered the lagoons with a layer of ice, then put down a geotextile, or a woven sheet of polymer, and a mixture of soil and wood chips. During the spring thaw, the ice layer melted, allowing the geotextile cover and the soil/chip mixture to cap the lagoons. Now sealed off, the lagoons were seeded for a vegetative cover.

The lagoons have worked out so well that they were recently included within the boundaries of Wisconsin’s new Capital Springs Centennial State Park. The lagoons are part of a corridor long valued by bird watchers for its variety of habitat.

Edil’s project cost about $600,000 and took just over four years. “It saved a lot of money for water users in the Madison area and it also converted a contaminated and unsightly area into part of a state park and wildlife refuge,” he says.