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Extent of superblock contamination unknown

Posted on 07 March 2017 by Calvin

Cleanup will also include 51.2 million pounds of building materials

A site with more than a century of different land uses, some of them messy, can mean a big cleanup day. Pollution cleanup is a major part of work to develop a Major League Soccer stadium in the Midway. Cleanup is being led by the St. Paul Port Authority, working with the city, property owners, contractors and the Minnesota Pollution Control Agency (MPCA).

A Feb. 14 city site plan review and look at MPCA records indicate the complexity of cleanup for the superblock bounded by St. Anthony, Snelling and University avenues and Pascal St. While cleanup has gone on over the past 30 years in different parts of the property, much more work is ahead.

The stadium project is the focus of an action plan, filed with the MPCA, detailing cleanup. The property is also enrolled in the MPCA’s Voluntary Investigations and Cleanup (VIC) Program and the Petroleum Brownfields Program. Monte Hilleman, who leads pollution cleanup efforts for the Port Authority, said that as the rest of Midway Center is redeveloped, more response action plans will be developed and filed with the state.

Gary Krueger supervises the MPCA’s VIC Program. Krueger said that while redevelopment of urban sites can reveal soil and groundwater contamination, proper cleanup can transform a blighted property into an asset.

“You have to keep in mind that the long-term benefit to the community is to have a site thoroughly cleaned up and reused,” Krueger said in an interview. “It’s a win-win to have property improved and contributing more on the tax rolls.”

Site cleanup is part of an $18.4 million package of stadium public improvements the St. Paul City Council approved last year. The city is contributing almost $17 million toward infrastructure including parking, plazas, sidewalks and streets, with about $1.5 million for pollution cleanup. The Port Authority has already obtained grants for the cleanup work and will seek more funding as needed.

Lead contractor Mortenson Construction estimates that excavation for the stadium would go as deep as 40 feet. “This is going to be a massive earthwork operation,” Hilleman said.

Some clean soils can be reused on-site as fill. One example is below Rainbow Foods, which originally was a department store. Its large basement will be filled in with clean soil from stadium site work.

Contaminated soils aren’t as easily reused. Contamination in the stadium site area includes petroleum byproducts, especially in the southwest corner of the site, Hilleman said. Contamination has been found in soil, soil vapors and groundwater as deep as 30 feet.

A combination of cleanup and containment measures will be used as the stadium is built. For example, contaminated groundwater can remain, but the stadium structure would be built in a way to keep that contamination out.

Some contaminated soils can be buried in the street right-of-way. Other contaminated soils can be taken to landfills licensed for contaminated soil disposal.

Then there is demolition of Midway Center itself. The 2016 Alternative Urban Areawide Review (AUAR), which outlined potential project environmental impacts, indicates that demolishing the entire shopping center will generate 25,600 tons of building debris. When all of the parking lots are removed, that is expected to generate about 650,000 square feet of bituminous parking area. The AUAR indicated that up to 70 percent of building material, and 90 percent of bituminous, can be recycled.

The shopping center, which opened in 1957, will need to have materials removed before demolition, such as asbestos, lead-based paint, refrigeration equipment, lights and other regulated wastes.

Krueger said that St. Paul and the Port Authority have a long track record of cleaning and reusing contaminated sites. With urban redevelopment sites, there’s often a long history of different land uses, said Krueger. “So you may not always know what you’ll find.”

That’s true of the superblock. Much of the block was used as a stable and horse racing track in the late 19th century. Streetcar operations there began in 1890. A larger streetcar maintenance building, which later became the Snelling bus garage, was built in 1907. Some cleanup was done after the Snelling garage was demolished in 2002, including the removal of more than a dozen fuel tanks.

Last year properties around University and Pascal, including the parking lot at the northeast corner of Midway Center, were placed in Minnesota’s Superfund Permanent List of Priorities. Inclusion on the list provides additional financial resources for pollution monitoring and cleanup, as well as determining the level of risk. Contamination found there included soil vapor contamination from chemicals, including trichloroethylene (TCE) and perchloroethylene (PCE).

It’s not clear yet where the University-Pascal area contamination came from but in the 1990s what was called the Midway Plaza VIC site was located south of University between Snelling Ave. and Pascal. That contamination was linked to a now-closed area dry cleaning business. The site, which had groundwater and soil contamination and soil vapors, was cleaned up and taken off of the state’s VIC rolls in 2000.

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