By Jerry LaMartina
The Mission City Council is looking closely at alternatives for fixing problems caused by erosion of the Rock Creek Channel between Nall Avenue and Roeland Drive..
In an Oct. 26 work session, council members and other city officials discussed three main options for addressing the problems, based on an analysis the city hired GBA to conduct. Public Works Director John Belger detailed the options at the work session.
- The first option is to buy out two houses on 60th Terrace and a Mission Bank parking lot, Belger said. The group’s consensus was that this option wasn’t viable because of the property owners’ probable unwillingness to sell.
- The second option is to leave the channel open and build retaining walls along the project’s entire length. This would cost the city an estimated $4.7 million. Additional costs could be paid with Johnson County Stormwater Management Advisory Council (SMAC) money, if the city can provide sufficient matching funds, which it currently can’t, City Administrator Laura Smith said. “We don’t have the matching funds right now for a project of this size without an increase in the storm water utility fee,” Smith said.Typically, between $12 million and $15 million a year in SMAC funds is provided for projects in the county. The current list of projects eligible for 2018 funding totals $27 million. Projects are granted SMAC funds based on an assessment of the projects’ priority, including the potential for loss of life and damage to habitable buildings, Smith said. Erosion is considered a lower priority.
- The third option is to leave the channel open and build retaining walls only where erosion is occurring, mainly on the corner behind Mission Bank near the homes being affected, and to stabilize a gabion wall in that area. A gabion wall is a basket or cage filled with soil or rocks used to build a support or abutment. This alternative would cost the city slightly more than $1.6 million.
GBA also told the city that a short-term solution would be to protect the gabion wall behind the two affected houses and remove a rock bar to divert water in the creek. This would cost about $37,000 and would be “a very temporary solution” that wouldn’t stem erosion, Belger said. That would require grading the slope, as alternatives two and three would include.
In order to be considered for SMAC funding in 2018, the city would have to have GBA prepare and submit a preliminary engineering study by the end of this year, Belger said.
“The thing about a creek is Mother Nature always wins,” he said. “(Alternatives) two or three would be a semi-permanent solution. With (alternative) two, you basically protect everything. With three, you’d protect areas that are eroding right now.”
Mayor Steve Schowengerdt said that he was mainly concerned about “health, safety and welfare.”
“I’m not trying to be hard on the bank or anybody, but whenever you buy property next to a creek, you have to expect erosion …,” Schowengerdt said. “Our main responsibility is for safety.”
The erosion problem with Rock Creek has been known for at least 10 years, several council members said.