These five towers, seen in 2006, are a remnant of the Gopher Munitions Works, a WW II-era munitions plant in Rosemount. They are being demolished to redevelop the site, not part of UMore Park. (Trisha Collopy — Star Tribune file/The Minnesota Star Tribune)

Remains from World War II-era manufacturing in Rosemount that became an urban eyesore will soon be history.

Bolander Construction of St. Paul has begun demolishing a set of abandoned smokestacks and a round gas tank at the University of Minnesota's UMore Park property near County Road 46. The removal will cost $270,000 on a segment of the more than 5,000-acre research site that's also undergoing environmental assessment for potential development.

"If there was any viable use, and they could be converted into something, we'd consider it," said Ken Kerns, the U's Department of Environmental Health and Safety vice president. "But these were just sitting there."

The U.S. Department of War first opened Gopher Ordnance Works, a smokeless gunpowder production plant, at what is now UMore Park during World War II. The plant was one of several across the country that the War Department hastily ordered for military production after Japan attacked Pearl Harbor in 1941.

By 1947, the federal government passed the deed to the U, which has since used the area predominantly for agricultural work and lab waste. The U has also leased land to agricultural and commercial tenants, including a gravel mining company. In the mid-2000s, a vision for a 30,000-resident utopia gained traction but soon fizzled.

Despite seven decades of inactivity, the smokestacks, visible from the highway, drew visitors. They tagged the site with graffiti and littered the grounds, Kerns said.

Two years ago, the U began documenting potential hazards on the site, Kerns said. Crews identified pits and trenches surrounding the stacks, which were only loosely covered by materials such as plywood. The contractors will fill the holes with concrete debris after demolition.

Local law enforcement hopes the demolition will deter explorers.

"We do stop people on a regular basis … for trespassing," said Rosemount Police Chief Mitchell Scott. "It's in everybody's best interest."

The U is now studying UMore Park's groundwater and soil for potential contamination and will publish results by the end of the year, said Gary Krueger, a supervisor for the Minnesota Pollution Control Agency who's overseeing the studies.

"We're just getting a better idea of what contamination issues they're going to have to deal with if they move forward" with development, Krueger said.

Natalie Daher • 612-673-1775