Here’s what to know about $800M in upgrades happening at 2 aging JoCo wastewater plants

Johnson County handles roughly 60 millions of wastewater daily. Above, water heads back out to the creek after going through treatment at the newly expanded Tomahawk Creek Wastewater Treatment plant in Leawood. Photo by Lucie Krisman

Two major improvement projects costing more than $800 million combined are bringing some much needed upgrades to two of the county’s oldest wastewater treatment facilities.

What’s going on? The two facilities, the Tomahawk Creek plant in Leawood and the Myron K. Nelson facility in Mission have both needed updates for years.

  • The Tomahawk Creek facility, 10701 Lee Boulevard, was originally built in the 1950s and was recently expanded in a nearly complete overhaul that finished in May.
  • The Myron K. Nelson plant, 4800 Nall Avenue, dates back even further to the 1940s, and a major renovation project there is just now getting underway.
  • The two facilities combined process more than half of the county’s wastewater each day.

Bigger picture: Don’t worry if you don’t spend a lot of time thinking about the county’s wastewater system. (That’s kind of the point.) But you should know:

  • Across its six facilities, Johnson County treats roughly 60 million gallons of wastewater every day.
  • And it’s at wastewater treatment plants like Tomahawk Creek and Nelson that the county’s sewage gets filtered and solids are removed so it can be safely discharged back out into the environment.
Johnson County handles roughly 60 millions of wastewater daily. Here’s how two major improvement projects on the county’s oldest wastewater facilities will help keep it flowing. Photo by Lucie Krisman

Here’s more about what these two major projects will do to impact the county’s wastewater system:

What are these projects and what do they cost?

  • The Nelson improvements project is a years-long effort just kicking off this year, entailing a full upgrade on the aging facility’s infrastructure — including its buildings and equipment, like pump stations.
  • It is slated to cost $574 million, part of which will be paid for through a $281 million loan from the Environmental Protection Agency, and work is expected to last through 2029.
  • The now-completed Tomahawk Creek facility expansion made Tomahawk Creek a “completely new facility”, according to county officials, equipping it with new concrete, pumps, structures and underground utilities.
  • That project, which had been ongoing since 2018, wrapped up in May, costing the county $270 million.

How will these projects help?

  • Isaac Crabtree, county managing engineer, said the aim of the Nelson improvements are two-fold; they’ll help the facility keep up with Kansas Department of Health and Education regulations and they’ll replace equipment that is reaching the end of its useful life.
  • “Our infrastructure is very obviously showing its age. So part of it is rehabilitating facilities that are kind of at the end of their useful life,” he said.
  • At Tomahawk Creek, county managing engineer Alex Szerwinski said the technical aspect of the improvements there will help the county keep a closer eye on how the facility is functioning, including the plant’s computer system that captures real-time data about how the plant is functioning at any given time.
  • “That’s a really critical way to help run the plant now,” he said. “All our facilities have that … system, but we’re going to see more and more of that.”

How much wastewater do they handle?

  • The Nelson facility has the capacity for 15 million gallons of wastewater, while the Tomahawk Creek facility’s capacity is 19 million gallons.
  • According to wastewater officials, Johnson County handles roughly 60 million gallons per day countywide, but it has the capacity to treat up to 70 million gallons daily.
  • As far as how this fits into the county’s total bandwidth, this means the Nelson facility handles approximately 25% of Johnson County’s wastewater, while Tomahawk Creek handles roughly 32% of it.

How has population growth affected this?

  • As Johnson County’s population has increased, so has wastewater usage.
  • Crabtree said this has led to the building of more watersheds, or land areas that collect precipitation and push them back out to bodies of water, but future population growth won’t necessarily have the same effect.
  • “There won’t be really much increase in flow to this facility [Nelson] over time because there’s not really any new development occurring in the watersheds,” he said. “There’s not really any new sources to bring in more water, but over the almost 75 years since this facility has been in existence, it’s steadily increased up to this point.”

Will there be more upgrades or facilities built?

  • While county wastewater officials don’t necessarily think new wastewater facilities will need to be built, they say there could be more refurbishing and expansion of existing facilities in the future.
  • For example, the county’s long-term capital improvement plan includes a look into whether facilities like Overland Park’s Blue River facility and Shawnee’s Mill Creek facility might need to expand as their respective areas in the county grow.
  • “Where we do see growth is in the southern part and western parts of the county,” Crabtree said. “As as the county grows southward and westward in terms of population, there will be changes to the treatment plans in the future.”

How much do residents pay for this?

  • Instead of through property taxes, Johnson Countians pay a monthly user charge for wastewater services.
  • Crabtree said the average customer household uses roughly 4,000 gallons of wastewater a month, which would amount to approximately $45.28 monthly.
  • Crabtree said Johnson County residents might expect a 5% annual increase in what they pay for wastewater, but this won’t be a direct result of these two improvement projects. That increase factors in all of the work Johnson County is doing on its wastewater infrastructure.
  • The rate that customers pay is determined by averaging usage from the winter months, when customers might be using less water.
  • “We exclude the summer months because people are using more water they’re watering their lawns or garden,” Szerwinski said. “So based on that, we take that snapshot of what happens during the winter. And then we feel like that gives a more fair charge to everybody.”