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Attendees at a public meeting last week held to gather input on the St. Croix River Osceola to MN bridge project,  learned an estimated cost to replace the circa 1953 span is estimated from $30 to $45 million.  The extremely complex undertaking is slowly making its way through environmental and “constructibility” review aiming to stay on track for a bridge closure in spring 2027 and a new bridge opening in fall 2028.   Associated clean-up and related restoration tasks in and around the riverway would happen in 2029.

The public hearing was part of required steps to adopt the Environmental Assessment Worksheet, for which public comment  is still being accepted until December 26.  The determination if the assessment documents are sufficient, plus project findings will be issued in spring 2025. 

The Wisconsin and Minnesota departments of transportation are lead agencies.  There is a long list of other government entities involved;  ranging from both states’ Department of Natural Resources, to the Army Corps of Engineers, the state Pollution Control agencies,  Soil & Water Conservation districts, and of course the National Park Service, which Congress mandated in 1968 to oversee the St. Croix National Scenic Riverway.

The Federal Highway Administration is expected to fund much if not all the bridge project.  (The state of Minnesota does have improvements defined, potentially, for the #243-Hwy. 95 intersection nearby the bridge project.)

To submit concerns or suggestions about the environmental assessment send mail to: MNDOT, 1500 West County Road B2, Roseville MN 55113 or send email to [email protected]. Everything is on-line at the project website,  and hard copies are at the Taylors Falls Library or Franconia Town Hall, if you can’t access the digital versions.

The bridge now is 674 feet long and 34 feet wide.  It has an average daily traffic count of 5,600.  The new proposed span becomes a bit shorter, utilizing different pier placement,  but remains in the same alignment. The corridor will be widened for safety improvements, and adding non-motorized use such as walking and bike riding.  The new corridor will accomodate two 12 foot lanes for vehicles, two 4 foot shoulders, a foot path on the outside edge of 12 feet in width.  The layout is in response to the public expressing a desire for better walking/riding between Osceola through to the landing on the Minnesota side.  (See color graphic)

When the old bridge deck comes down it will not be “dropped” into the riverway, according to the documentation in the assessment.  Plans are to demolish the deck a section at a time, trying to keep the span useful as a one-lane crossing for as long as possible.

Demolition of the existing piers will require silt curtains to trap debris.  The environmental assessment expects work to be facilitated with smaller pontoon barge platforms, due to the riverway depth.  

The final bridge will appear somewhat less elevated than the existing one. (See artist rendering.)

When new beams are lifted into place to support the new deck there will be two 300 ton cranes and a 400 ton crane (on the Wisconsin bank of the riverway) utilized.  The larger crane will require cutting away the bank,  to create a temporary level spot a little downriver of the bridge.

Materials deliveries and staging are coming from the Minnesota side, due to the steep bluff contours on the river’s east side.   At this time the landing on #243 is probably going to be used for contractor staging for at least the initial phase.  The Wisconsin road alignment etc. work will be phased in towards  the later part of the timeline.

The project planners are aware the St Croix is habitat for a variety of freshwater mussels— some of which are quite rare.  The planning documents anticipate the need to relocate or otherwise “protect” these valuable “ecosystem engineers.”  Mussels help filter river water and  benefit other species.  They reduce bacterial populations with their filtering activity.

The pier locations have been placed to not impede the Osceola Creek confluence.

The “Contaminated Materials Team” chapter within the assessment has also highlighted potentially contaminated locations within 500 feet of the bridge work zone (a landfill, spill and leak sites) after inspecting Pollution Control Agency files,  and activity will avoid contact with these.

Anybody who regularly makes use of the bridge should plan accordingly;  because the only detours are at Taylors Falls and the Hwy 36 bridge south of Stillwater.  Estimated extra time for these detours are 15 minutes one way for crossing at Taylors Falls and 30 minutes to the crossing at Highway 36.

   

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