When ground was broken last month on a long-sought nature sanctuary along Interstate 35E in St. Paul's North End neighborhood, it marked the beginning of the transformation of a strip of land that from 1891 until the late 1970s was a railroad right-of-way.
One of the first tasks facing the city of St. Paul as it begins work on the new Trout Brook Nature Sanctuary will be to deal with the environmental legacy of that railroad heritage. Elevated levels of arsenic, lead and petroleum byproducts have been detected on the site, requiring a $600,000 cleanup which has been funded by a U.S. Environmental Protection Agency grant.
As such brownfield remediations go, it's not a huge job, but the presence of the polluted soil played a key role in how the project could be pulled off with a $5 million development budget. The vision for the 42-acre green gem is to liberate the historic Trout Brook from an underground storm sewer system and return it to the surface as a meandering stream.
The biggest concern was making sure the site was thoroughly analyzed beforehand, said project manager Kathleen Anglo of the St. Paul Parks and Recreation Department.
"There is going to be a massive amount of excavation involved with the project — we're going to be digging a new 3,000-foot stream channel through the site as well as excavating for a series of ponds," she said. "We needed to do extensive testing in those areas to make sure we weren't going into this blind as to the level of contamination that was there."
The latest in a series of environmental studies dating back to 2003 was completed in March by the Roseville-based environmental engineering firm Braun Intertec, which concluded the contamination could safely be dealt with by overtopping public areas with clean fill found elsewhere on the site.
Hidden pollution, nasty surprises
Anglo said the city is well aware that with such brownfield projects, hidden pollution can provide nasty surprises and bump up construction costs, and so it has set aside some contingency funding if that's the case.
"We're keeping our fingers crossed," she said. "The contamination isn't at high levels, but it was used for many years as a railroad yard, so you have to be aware of it."