Although Jefferson City and Cole County have worked to improve stormwater infrastructure issues in recent years, heavy rains at the end of last month have shown more remains to be done.
Cole County took 20 calls about problems related to the recent storms, 15 of which were stormwater-related, Public Works Director Eric Landwehr told the County Commission last week.
"Some of the problems were in areas that we already knew about, and some were in areas where we hadn't encountered problems before," Landwehr said. "Most of these are pipes flooding or an inlet pinching in on itself and it wasn't able to handle the flow."
Areas of concern include the Ravenwood Subdivision off Business 50 in Apache Flats, which has persistent flooding issues.
"This subdivision is private, and the roads are not within the jurisdiction of the county," Landwehr said. "They are at the bottom of a 2,050-acre drainage area that begins all the way up at the Cole County Fairgrounds."
The Natchez Trace subdivision off Henwick Lane and the Westview Heights subdivision — specifically the South Brooks Drive and Bagnall Drive areas — also saw flooding in this past storm.
The Randall Drive subdivision off Scott Station Road experienced some flooding issues Landwehr said he's never seen before.
"This is an older subdivision that needs stormwater upgrades that we are aware of, but we've never had issues of flooding to my knowledge," Landwehr said.
Similarly, Jefferson City officials received more than 30 calls last week about stormwater issues and expected to receive more.
"It seems to be now we're kind of in the middle of town here toward the west side of town mostly," said Matt Morash, Jefferson City Public Works director. "It's really more west side and a little less widespread damage than we thought."
For the most part, he said, people had flooded homes as water from nearby creeks or the stormwater system got in through openings. There were also a few calls about the sanitary sewer system.
"We'll uncover more of these as time goes on," he said. "Many people are just working on the problem to get it fixed before they contact us."
Generally, Morasch said, those with issues are in homes built in the 1980s or earlier, prior to the stormwater code going into place or buildings that were originally constructed outside of city limits.
"Mainly the issue you find on pretty much all of these floods are the elevation at which the home or structure is built doesn't necessarily accommodate the creek or stormwater pipe flow or something like that," Morasch said. "Where it's very flat to the creek, there's no room for the creek to flood out without getting into their home."
While some issues are quick fixes, Landwehr said, others are in areas of the county where the stormwater systems aren't capable of handling the kind of rains, 3- to 6-inch downpours, like what was seen June 24-25.
"Some of that's due to when the systems were built," Landwehr said. "From the late '70s to early '80s, when some of these older subdivisions were built, their design was not done like what we would do today. They have pipes that are under-sized and don't have enough inlets, which leads to water running over roads and goes into yards."
Landwehr said Cole County ran into this in 2017 when heavy rains hit the western side of the county and showed where stormwater work needed to be done. He said they had addressed most of those, but now they will compile a list of these new areas found during last week's rains.
"Over the past 15 years, we've made a lot of stormwater improvements," Landwhr said. "At last count, we had somewhere in the neighborhood of 250 new inlets and junction boxes along with 15,000 feet of new pipe installed."
Addressing stormwater issues is complicated because it's a multi-faceted issue, Morasch said.
"We have river flooding, and we're experiencing some of that with this last rain as well," he said. "That mainly focuses on the backwater of the river. Many of these problems were flash flooding related; that's a little bit of a different issue. Then there's the infrastructure issue of just the deteriorating infrastructure. Some of these might be caused by that, but I'm not certain yet."
In terms of flash flood situations, the system takes some water, but there's a period of overland flow that has to occur, Morasch said.
"So if you live or have a property, commercial property or otherwise, next to one of these, be aware of that and have your property designed in a fashion that can accommodate those flows," he said.
Culverts and creeks can get clogged with debris, he said, which can happen at any time. Those overland flow paths help direct water when there's clogging or the system is overwhelmed.
Storms like those at the end of June, Landwehr said, show addressing stormwater issues is an ongoing process.
"One part of the solution would be more stormwater detention, especially the Apache Flats area," he said. "That drainage area going through there is huge, over 2,000 acres. Some places where the homes were built, you can't flush that much water through that narrow of an area and not expect things to happen. There are ways, if we can detain some of that water upstream, we can slow down the amount of water coming through there, going through at a slower pace and not causing the issues that are happening now."
Landwehr said it would take a significant study to determine where the best places are to do detention. In the county's half-cent sales tax extension for capital improvements that passed in April, Landwehr said, there is money set aside for stormwater work that could be used to pay for such a study. He added if they moved some other public works money around they could possibly get the study started this year.
"It would maybe take six months to complete the study," Landwehr told county commissioners. "To implement the recommended changes would take more time. You'd have to find funding and locations, but we do have county-owned property, two old lagoons that were taken out of service in the old Gray's Creek Sewer District — one located just to the east of Pioneer Trail School, and the other is behind Larry's Honda. I think they could be utilized to help, but we'll have to look further upstream, maybe into the Jefferson City limits, for some areas to slow the water down."
Jefferson City has discussed a stormwater utilities fee in the past as a way to direct funds specifically toward system upgrades and maintenance, but that never went out for citizen approval.
Morasch said Emergency Management is collecting information from the city, county and residents about damage to see whether there might be grant options to help repair damage, but he thinks "the threshold is pretty high."
In the past, the city and county have received federal funds after major flooding events to rebuild levees or roads that caved in, but for the most part repair funding comes from the city budget.
The Jefferson City Public Works Committee is scheduled to discuss stormwater issues at its Thursday meeting and give members of the public time to speak on the topic.
In the Cole County capital improvement sales tax, there is $3.5 million set aside for bridges, culverts, low-water crossings and stormwater.
"We have several smaller-scale projects that we are prioritizing for the sales tax period beginning next year," Landwehr said. "There are at least 10 areas, with one priority area being Lakewood Subdivision. Most of the locations go hand in hand with subdivision street repairs and resurfacing. We always upgrade stormwater pipes and inlets before we do major street repairs and overlays."
When asked how much would be needed to sufficiently fix the entire stormwater system, Landwehr estimated it "will easily be in the $30 million range."
"It is a little hard to pinpoint an accurate number because there is so much more that goes along with stormwater replacement work such as street repairs, curb and gutter, etc., and this is usually rolled into the total project paid by the stormwater funds since it is incidental," he said. "Each project is unique, and we don't know how much incidental work is necessary until we begin design."