It’s not going to be cheap but the fix that will reopen West River Parkway is supposed to be done by next fall.
That’s the schedule outlined to the Park Board last week as it gave preliminary approval to a rough design that involves installing four retaining walls on the West Bank bluff where a mudslide last June closed car, bike and foot traffic. The early cost estimate of the fix is $6 million, including emergency response and design costs.
There will be two five-foot retaining walls installed near the bottom of the hillslide where 4,000 cubic yards of soil and debris collapsed. Another major wall that could reach 20-feet high will be installed near the property line between the Park Board property and the University of Minnesota Medical Center – Fairview, which sits at the top of the bluff. A smaller wall will sit above that.
Commissioner John Erwin asked the question on the minds of the roughly 6,000 motorists a day forced to find an alternate route: “We’re all getting asked -- why so long?”
Project Manager Deb Bartels said it’s taken since this long since the June 19 slide for detailed investigation of the 10,000-square-foot section of bluff. That that had to be done to weigh what type of fix would stabilize the remaining hillside. Those tests have included seismic and laser diagnosis and borings.
The wall work, along with replanting the hillside, is supposed to start in June and be done by fall. The pending approval of the design by the Park Board later this month will allow Barr Engineering to finish the design. The project is expected to include improvements in collecting how rain is handled near and at the site so that soils don’t slump again after becoming saturated.
The Park Board so far has committed more than $1.1 million to responding to the slide for costs ranging from hauling away debris to installing barricades to temporarily covering the hillside with semi-porous sheeting to minimize further erosion. The biggest chunk of that has gone to Barr, hired by the board in September.
The Park Board expects federal disaster relief reimbursement for 75 percent of the cost, and is hoping for state disaster relief to cover the rest. That’s up to the Legislature.
The potential for graffiti to cover the new walls was raised by Commissioner Jon Olson when he viewed the design. Staffers said they expect the wall to be camouflaged eventually as vegetation grows in.
Just how the walls will be surfaced has yet to be defined with historic preservation officials, but it’s clear the design won’t mimic the area’s limestone Works Progress Administration walls that date from the 1930s. Imitation is a no-no with preservation officials, but the walls will be compatible, Bartels said.
(Illustration below by Barr Engineering shows hillside with approximate placement of new retaining walls before revegetation.)