By Kevin Wilcox
The Minnesota DOT is racing the clock to move a 1.5 mi section of highway in iron ore country after its easement expires.
To replace a section of U.S. Highway 53 (shown in purple) that needs to be cleared for taconite mining, the Minnesota Department of Transportation is focusing on a 3 mi alternative (shown in orange) known as E-2. This alignment traverses exceptionally unforgiving terrain and would require the tallest bridge the state has ever built. Courtesy of MnDOT
March 31, 2015—It would be difficult to find a highway project that includes more challenges per mile than the one being undertaken by the Minnesota Department of Transportation (MnDOT) as it seeks to relocate approximately 1.5 mi of U.S. Highway 53, which links the towns of Virginia, Gilbert, and Eveleth.
The highway extends across a right-of-way on land that isn't owned by MnDOT and contains something more valuable than its transportation facility: vast swaths of taconite, a type of iron-ore-bearing rock. And as its easement to use the right-of-way expires, the department needs to move the highway out of the way of miners. Finding a suitable new alignment is difficult because the ground surrounding the city of Virginia is "pretty much all taconite," says MnDOT's project director Patrick Huston, P.E. "If it's not being mined right now, it's probably going to be mined at some point in the future. It doesn't leave a lot of options."
The department's preferred realignment for the route is to the north and east of the current location. Yet, at a scant 3 mi in total length, the project traverses exceptionally unforgiving terrain and would require the tallest bridge the state has ever built. The move will also require the acquisition of expensive land and mineral rights so the state won't face this situation again any time soon.
The roots of the project stretch back to 1960, when United States Steel Corporation, headquartered in Pittsburgh, which owned the land, issued the state an easement to build the highway on the current alignment. The easement came with an agreement that when it became time to mine the area, the state would receive notice and the easement would expire three years after that notice. The agreement further stated that if that notification came prior to 1987, landowner U.S. Steel would pay for the highway's relocation. After that date, the state would be financially responsible for the move.
The bridge in the E-2 alignment (shown in orange) crosses a former mining pit filled with rubble. The E-1A alignment (shown in green) features a large constructed berm, but that option would put the highway closer to active mining and is more expensive. Courtesy of MnDOT
That notice arrived in May 2010 from the current landowner—RGGS Lands and Minerals, of Houston, which purchased the property from U.S. Steel—and the United Taconite division of Cliffs Natural Resources, in Cleveland, which holds the lease on the mineral rights. The state has negotiated a 2017 deadline for completing the move; between now and then it must develop an environmental impact statement (EIS).
"There are no good solutions," Huston says. "It's been really a challenging project. And the bottom line is we have a deadline right now of May 5, 2017, to have our highway out of there and have that area available for mining."
The taconite under the current highway alignment is highly prized for several reasons. First, the deposits are shallow, and thus easily mined. Second, the taconite there is marked by high iron content and low silica. This high-quality ore can be mixed with lower-quality ore from other locations to create a highly competitive product.
How valuable are taconite deposits at the site? The MnDOT estimates it would cost between $400 million and $600 million to purchase the land and the mineral rights under the highway. As if that figure weren't far enough out of reach for a 1.5 mi highway project, it doesn't include the financial impacts to the mine from the inability to access the high-quality ore.
So the move is on. The MnDOT is weighing a series of options, some of which are far from promising. The concept of building a large berm to the north of the current alignment, through a previously mined area, is included in the EIS, but is not favored because it would be expensive, the bridge foundations would be subjected to the effects of nearby mine blasting, and it would place traffic in proximity to live mining.
A far western route has been examined, but is deemed unacceptable by local businesses because it replaces the 1.5 mi segment with a 13.5 mi route, producing serious projected economic impacts, which include $323 million in user costs over a 20-year period.
The final EIS is being developed now, and the MnDOT has identified a preferred alignment, known as E-2, which includes the bridge and 3 mi of four-lane highway. Until the EIS is complete that route isn't final. But with the deadline looming, the state is moving forward on the project anyway. "From an engineering standpoint, E-2 is the one that was identified by all of our functional areas to be the preferred [option], and then when you rippled the costs into it, that confirmed it as the lowest-cost option, also," Huston explains.
For just the second time in its history, the MnDOT is using the construction manager/general contractor delivery method on the project. MnDOT has selected Parsons, headquartered in Pasadena, California, as the lead designer, and Kiewit, headquartered in Omaha, as the lead contractor on the project.
The preferred alignment crosses over the Rouchleau mining pit, now filled with water, via a 1,100 ft long bridge, 200 ft above the surface of that water. The MnDOT estimates the costs of the project between $180 million and $240 million, which includes engineering, right-of-way acquisition, mineral-related easements, and construction costs.
Huston says the EIS process probably won't be completed until this fall. "We can't go to construction on this alignment until that's done, and the final environmental impact statement concurs that E2 is the alignment with the least impact," Huston says. "But we are charging ahead with this E2 design in order to meet the deadline. If we wait until next fall, we will be a year or two late. We think it's a low risk, but it is still a risk," he admits.
"Our state right-of-way engineer is spending about 95 percent of his time on this one project, trying to secure these easements with all of these mineral issues," Huston adds. "We want full bridge design by the fall so when we get the environmental process completed, we can charge ahead."
To expedite the process, the MnDOT plans to order some of the massive steel members needed for the bridge later this year, using state funds. The manufacturing lead time for these girders, the largest of which will likely be 14 ft 6 in. high, is approximately 12 months.
Huston notes that the bridge team was hired in late February with a target to have plans sufficiently complete by April 30 to facilitate the steel order. "If you think of what it is going to take between now and [then]...that's intense," he says.
The early steel order isn't the only complication in the bridge design. The bottom of the 300 ft deep Rouchleau mining pit is lined with more than 100 ft of rubble. Contractors are drilling test piles of both 16 in. and 24 in. diameter to see how far down the foundations will need to go to reach bedrock; so far, some of the test shafts have gone as far as 170 ft deep to find solid rock.
"This is an enormous pit. You can imagine," Huston says. "We've got to get bridge foundations through...all this rubble and down into some of the hardest rock in the world for our substructures."
One of those foundation locations will likely be sited on the sloping east wall of the pit, where the design and construction teams face geotechnical challenges posed by layers of slate that dip to the north and west, as well as bedrock of varying levels of competency. Access to the east wall will be an issue, and the wall will need to be stabilized before workers can even cut a notch into the face and begin testing there.
Another significant challenge posed by building a highway in a mining zone is that the area will likely look much different in 20 years. The taconite deposits reach depths of 800 ft in some places around the City of Virginia. That creates some mind-boggling scenarios. "Someday this [highway alignment] could be mined up to, on both sides, and we are dealing with the geotechnical complexities of that," Huston says. "This might be like a big causeway with a pit floor five or six hundred feet below. How does all that look? How do you negotiate those easements? How do we make sure our bridge and embankment are safe in four dimensions?"
As if these challenges aren't enough, the current highway right-of-way contains utility service lines and the Mesabi Trail, a multipurpose, 24 ft wide pathway that is popular with snowmobile riders in the winter and ATV riders in the summer.
"This bridge is obviously very expensive. We are going to put a 14-foot-wide walkway on there, share the cost with the trail, and find a way to have pedestrians, bicyclists, snowmobiles, and ATVs share 14 feet across this bridge," Huston says. "We looked all over the country but can't seem to find anybody who's done that and can offer advice.
"We have our best and brightest—internally and externally—on this," Huston says. "It's pretty amazing, the caliber of experts we have on this. It is very challenging, but it's also very interesting. Everywhere you turn, somebody needs an answer. And nothing has an easy answer."