Turning a heavily polluted and contaminated area into usable land is no easy feat. Thousands of such sites exist throughout the United States that are listed among the U.S. Environmental Protection Agency’s (EPA’s) Superfund or National Priorities List, and many continue to lay waste. But such is not the case for one Superfund site located in Arden Hills, Minnesota, considered the largest contaminated site in the state and the entire Midwest.

The 427-acre property, the former Twin Cities Army Ammunition Plant (TCAAP), has been undergoing the complex transformation from a former ammunition plant to a highly sought-after commercial and residential property. Demolition and remediation firm Carl Bolander & Sons Co. (Bolander), St. Paul, Minnesota, has helped make it happen.

TCAAP’s history dates back to 1941 when the facility was established by the U.S. government’s war materials production program to manufacture munitions for American and Allied forces during World War II. Construction began in August 1941 and by February 1942, the plant was producing .30 caliber and .50 caliber cartridges. During the plant’s peak in 1943, it employed 26,000 people—more than half of whom were women. By the time the war ended in 1945, the plant had produced an estimated 4 billion rounds of ammunition.

After the U.S. declared victory over Germany and Japan, the plant became inactive, but was intermittently reactivated to produce arms and ammunition during the Korean and Vietnam wars. The site continued to grow into a self-contained community, hosting other tenants throughout the years, with 40 miles of electric and telephone wire, 83 miles of sewer, and 37 miles of road and railroad track. The plant was mothballed by the military in 1976 and ceased all operations by the late 1990s.


TCAAP was placed on the National Priorities List as the New Brighton/Arden Hills Superfund Site in 1983. According to the Minnesota Pollution Control Agency (MPCA), contamination resulting from past ammunition manufacturing operations at the facility had been identified in groundwater, soil, sediment and surface water.

“TCAAP operated for several decades during a time when there were no laws governing disposal of chemicals,” the agency states on its website. “During these years, the Army generated industrial wastes that were disposed of using accepted practices of the times, which included on-site dumping, burial and open burning. The manufacturing processes and historical disposal areas at the facility caused contamination of groundwater, soil, sediment, and to a lesser extent surface water.”

Over the years, the Army, EPA and MPCA have worked jointly to discover the extent of contamination and to clean up pollution that poses a risk to human health and the environment, based on the current land use, says MPCA.

Environmental remediation has taken place at the site since the 1980s and had included:

  • more than 94,000 cubic yards of contaminated shallow soil have been remediated to Army industrial use cleanup standards;
  • more than 200,000 pounds of chlorinated solvents have been removed from the deep soils;
  • approximately 1,500 cubic yards of polychlorinated biphenyl (PCB)-contaminated soil have been incinerated;
  • approximately 1.2 billion gallons of groundwater are treated yearly; and
  • approximately 226,000 pounds of chlorinated solvents have been removed from the groundwater.

This level of remediation has designated the site as “Army Industrial.” MPCA estimates groundwater treatment will take place until 2040, which will be paid for by the Army. While the historical waste and disposal areas had been addressed, getting the site safe for residential and commercial use would require additional investigation and cleanup.


The Bolander’s Andy Ristrom, recalls first bidding on the cleanup work at the site back in 2008 when a private firm wanted to redevelop it. That deal fell through when the economy tanked and the Army decided it wanted to sell the property to a public entity. Ramsey County, where the site is located, expressed interest in purchasing the property and locating the new Minnesota Vikings’ football stadium there. Ultimately, the stadium is being rebuilt in Minneapolis at the site of the old Metrodome instead, but the initial negotiations brought attention to the site as a spot for redevelopment.

“This got the county thinking they could buy the site and clean it up,” says Ristrom. Ramsey County bought the property from the federal government for $28.5 million in April 2013.

As one can imagine from such a contaminated area, lenders were not eager to front the money for the project. “Lenders needed assurances that they would not be left holding the bill for uncontrolled cleanup and demolition costs,” Ristrom says. Ramsey County wanted the contractor to carry the risk, so, “We started putting together a fixed-cost proposal to clean up the site, taking the data we had of what we knew was there as far as contamination and building demolition.”

Under this agreement, one lump sum contract took care of the remediation and demolition, placing Bolander and its partner Wenck, of Maple Plain, Minnesota, at risk for the cleanup. Ristrom says he is not aware of any other contracts structured in this manner.

“The job is probably the largest we have undertaken as a company for a fixed-cost proposal and one of the biggest demolition cleanups of that size in the entire state that has ever been done,” he says.

To get started, predemolition environmental surveys needed to be completed for each structure on the property, which included more than 90 buildings. Environmental remediation was performed on all the structures. Several specialty contractors were employed to perform remediation work. Ristrom says all buildings were cleared of regulated wastes, including bulbs, ballasts, mercury switches, furniture, cardboard, paper and general solid waste items not allowed in demolition landfills. Crews were able to salvage many for reuse, he adds.

Remediation prior to demolition was required to remove any mercury contamination present on concrete slabs and PCB contamination present on asbestos-containing material (ACM) transit siding. The heaviest PCB contamination was in and near Building 502, notes Ristrom, blaming the huge hydraulic presses and the PCB oil they contained for this contamination.

At its peak in 1943, the Twin Cities Army Ammunition Plant (TCAAP) employed approximately 26,000 workers, more than half of whom were women.

“A majority of the buildings contained thousands of lineal feet of asbestos window glazing and caulking,” Ristrom says. This also had to be removed before demolition could occur.

That was just above ground. Below ground were miles of steam and gas lines that formed what Ristrom describes as “a web of asbestos-coated pipes beneath the ground.”

Bolander enlisted the help of outside firms to assist with building abatement as well as wrapping and cutting pipes.

Pipe removal required careful excavation, exposure, abatement and removal of the lines. Specially trained operators and laborers wearing proper protective gear loaded material containing PCBs into lined trucks. The contaminated loads were taken to a hazardous waste landfill in Michigan.

Ristrom notes that most of the contamination at the site was related to solvents that created a groundwater plume and was much easier to clean up. As well, some of the lower-level PCB contamination (less than 50 parts per million) did not require special hazardous waste disposal.

Bolander’s partnership with Wenck included testing and analytical environmental work. Ramsey County hired Bay West to serve as the oversight firm. Bolander crews performed the actual digging and excavating work.


Of the buildings on the site when Bolander began demolition work in May 2013, 10 were hundreds of thousands of square feet, while the rest were much smaller. Demolishing all the buildings and returning the land to residential habitability took about two and a half years to complete. One of the first buildings to go was Building 102, the old factory building, which once housed two manufacturing lines within its 234,000-square-foot space. Heavy demolition machinery tore apart the building into heaps of steel and concrete debris. Building 115 was another casualty of the demolition process. It was a shell of the former power plant. Its asbestos and boilers had been removed years earlier.

More than 13,000 tons of steel and more than 400,000 tons of concrete and asphalt were recycled and reused from the site. Additional items that were reused include more than 300 steel beams that will be incorporated into new construction; six miles of railroad tracks that will be rerolled and used again for trains to travel on; and Douglas fir timbers recovered from some of the buildings. Ristrom explains that during the turn of the century, Douglas fir was a common building material prior to modern steel technologies. Its tall size and narrow growth rings developed from having to compete for sunlight with other trees, making it stronger than the trees that grow in the planned forests of today.

“New forests don’t produce trees like that,” says Ristrom.

The timbers are salvaged for reuse in new buildings as structural beams or used as flooring in high-end homes. “Building 502 and 104 were both timber-framed buildings. We salvaged as much we as we could to carefully deconstruct the buildings and keep the larger timbers intact,” Ristrom says.

In April 2014, approximately 40 buildings remained on the site and by October 2014, all the buildings were gone and the majority of the contamination had been cleaned up, according to Ristrom. Approximately 93 percent of the demolition debris was reclaimed and recycled.


The new development proposed for the land is known as Rice Creek Commons. Arden Hills and Ramsey County formed a Joint Development Authority to oversee the efforts to clean up and develop the site. The redevelopment will include a mix of residential, commercial and open spaces.

In November 2015, Rice Creek Commons announced that work to clean and clear the former TCAAP site had been completed. The county is now working with the MPCA through its Voluntary Investigation and Cleanup (VIC) program and the EPA to verify the work. The county will request that the MPCA and EPA delist the site as a Superfund for soil contamination in 2016.

“When we decided to purchase the TCAAP site in 2013, our goal was to return this vacant property into the economic and social engine that it once was,” says Ramsey County Commissioner Rafael Ortega. “Completing the cleanup puts us one step closer to creating a vibrant development that will strengthen our community.”

“It is exciting to see the incredible progress being made in a part of our community that has been underutilized for far too long,” says Ramsey County Commissioner Blake Huffman, who represents the area. “Rice Creek Commons represents an exciting opportunity to create jobs, development and tax base that are good for Arden Hills and for the entire county.”

The author is editor of Construction & Demolition Recycling and can be reached at ksmith@gie.net.