For the second time in months, Montgomery County is taking emergency measures to keep a road from crumbling into a waterway.
County commissioners voted to fast-track a bid process on an $800,000 fix to divert Little Twin Creek before it does irreparable damage to Manning Road.
“Back early this spring … we lost a lot of land all of a sudden,” said Joseph Dura, senior engineer in the Montgomery County Engineer’s Office. “All that backslope is gone; all the vegetation is gone.”
Erosion — speeding up as a result of more frequent and large rain events — left a 30-foot drop-off just 10 feet from the pavement, compromising the roadway and putting drivers at risk, Dura told county commissioners during a viewing of the project this week.
“There is an imminent failure potential for the road,” Dura said. “There is that hazard for the traveling public.”
It’s the second time this year county commissioners approved an emergency to fix damage caused by erosion. The same heavy spring rains also washed away part of Upper River Road near Miamisburg, leaving a guardrail dangling above the Great Miami River and forcing the county to close a stretch of the road in April.
The emergency measure allows the county to bypass advertising for bidders, shaving about 30 days off the project, said Montgomery County Engineer Paul Gruner.
For the past two years, the engineer’s office observed Little Twin Creek moving steadily but slowly toward Manning Road on the southern border of Jackson Twp. between Clayton and Venus roads. But weather events this year brought about a “clear hazard for the public,” Dura said.
“We weren’t anticipating doing this project in 2018, but here we are. We don’t have a choice,” he said.
As a safety precaution, a concrete barrier was placed alongside the stretch of Manning Road, which carries an average 2,200 vehicles daily, according to the engineer’s office.
More frequent, excessive precipitation is pushing more water down streambeds than in the past, Gruner said.
“The last couple of years have been bad years for rainfall … And last year the rainfall was seven inches above the rolling average: 47 inches instead of 40 inches. This year is more or less heading in the same direction,” he said. “All that causes the creeks and rivers to try to move out of their banks, and that’s what’s happening to us in a number of places.”
Evidence shows there is an increase in high-precipitation events in the United States, according to data from the National Oceanic and Atmospheric Administration and the National Center for Environmental Information. The data also show the percentage of U.S. landmass experiencing high-precipitation events expanded from 10 percent to 15 percent in in the last 18 years.
The plan along Manning Road calls for realigning the creek, armoring the southern bank into a stable slope and building various rock structures to “encourage the creek to go the other way instead of into the road,” Gruner said.
The project area lies entirely on private property, so the county is working with the owner on a permanent easement to allow for ongoing maintenance of the site, Dura said.
Environmental rules also leave a small window for completing the work this year, Dura said. Trees that are habitat to endangered species can only be cut between Oct. 1 and March 31. And due to the spawning cycle of fish, workers can’t disturb the creek between April 15 and June 30.
“We either have to get it done now or we won’t be able to get it done until after June,” Dura said.
The road is expected to close during November and December when a majority of the work will be completed. Work on the site will continue in the spring as native grasses and trees will be reintroduced so over time everything “locks into place,” he said.