NORTH MANKATO — What’s the city of North Mankato going to do with Judson Bottom Road?
That’s the question local officials are trying to answer, as city staff consider how to prevent the kind of car-sized boulders and landslides that have kept a one-mile stretch of the road closed since March.
“We’re looking at all options right now,” Public Works Director Nate Host said Monday.
While the city regularly closes the road in the spring due to flooding concerns, the boulders littering the road between Valerie Lane and the bottom of Lookout Drive prompted city officials to study the nearby bluffs in case more boulders fall in the future.
The remaining stretch of Judson Bottom Road belongs to Nicollet County.
Host told the North Mankato City Council last month area consultants examined the cliffside to recommend some solutions, which could include a liquified concrete layer over some of the cracking cliffside to hold it in place.
Trying to patch up the cliff may not be the best solution, however.
Experts say the Minnesota River Valley has been carved out over the years due to a series of floods, which has brought in a lot of dirt and silt. Consultants told the city increasing amounts of water and snowfall are getting into the rockface near Judson Bottom Road, where it’s absorbed by sand inside the ground and eroding larger rocks, resulting in landslides and the boulders on the road.
“Really the issue is the water coming over the top, getting into the ground and continuing to push out the growing size of these boulders,” Host told the council.
Council members are leaning toward clearing out and opening the road, which could be done in a day or two. Jim Whitlock said last month he’s heard from several residents who want the road open again for their morning jogs or daily commutes.
North Mankato Mayor Mark Dehen agreed.
“We’ll watch it and if it continues to be a problem then we’ll take steps to find a solution,” he said.
Host is hoping the council will tour the area before it’s reopened so members can get an idea of the kind of boulders coming out of the nearby cliffside.
Judson Bottom Road is a lone example of the kind of problems Mankato and North Mankato may face in the future. A group of Minnesota State University researchers completed a study over the past year that found almost 500 examples within the greater Mankato area of landslides, mudslides and rockfalls, which will only become more common due to increasing precipitation and more severe weather events.
North Mankato is embarking on a plan to maintain more of its ravines and cliffsides after city workers have found more evidence of erosion in recent years.
City workers surveyed all ravines south of Highway 14, including the area near Judson Bottom Road and found erosion issues in several places. Last week, the council approved a $710,000 bid from R & R Excavating for the first phase of a major erosion repair project at the ravine near the North Ridge neighborhood.
Host said Judson Bottom Road’s issues are minor compared to the North Ridge ravine but city officials plan to monitor and regularly inspect area ravines to head off future erosion problems.