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Frequently Asked Questions

Project Overview


What is the background of Tomahawk Creek WWTF?

The Facility was constructed in 1955 and has expanded over the years to treat flows from parts of Leawood, Overland Park, Olathe, and Prairie Village; however, the current Facility is not able to handle all of the flow it receives.  The current strategy for working with the high growth in the area has been to send approximately 60% of the incoming flow to Kansas City, MO (KCMO) and treat the remaining 40%.  This strategy has helped keep large capital costs low but has increased the operational costs of the Facility each year.  Over the past decade a couple of factors have led to the decision to upgrade and expand the existing Facility:

  • Kansas City is facing significant improvements to their infrastructure leading to a rate increase.  

  • The Environmental Protection Agency and Kansas Department of Health and Environment are requiring stricter discharge limits for things such as ammonia, nitrogen, and phosphorus.  


What are the drivers for the project?

Johnson County Wastewater looked at ways to control costs long term and minimize future rate increases.  Sending flow to KCMO makes costs unpredictable. Using the money sent to Kansas City to invest in our own facilities will generate future savings for ratepayers. Expansion is the most cost-effective way to meet future regulations and provide a long-term treatment solution to our customers. 

The three main drivers for the project are:

  1. New water quality regulations require upgrades to the existing Tomahawk Creek Facility to improve water quality in Indian Creek and downstream waters.

  2. Johnson County Wastewater is in need of a solution to control costs – 60 percent of current wastewater treatment cannot be handled at the current facility and is outsourced to KCMO at 2-3 times the cost of treating at a Johnson County Facility. 

  3. Majority of assets are beyond their useful expected life and need to be replaced.​

What are the goals of this project?
  • Provide the most cost-effective, long-term solutions for customers

  • Improve water quality using the latest, proven technologies

  • Preserve the high quality of life enjoyed by Johnson County residents  

How will the project improve our quality of life?

A long-term infrastructure investment at the Tomahawk Creek Wastewater Treatment Facility will preserve the high quality of life enjoyed by Johnson County residents by:

  • Protecting the environment and improving water quality in Indian Creek and for downstream communities;

  • Improving treatment operations by applying the latest technologies; and

  • Providing the most cost-effective, long-term solutions for customers.

Financial Costs/Savings


Why are treatment costs increasing?

Treatment costs will increase for Johnson County Wastewater due to two factors:

  1. New water quality regulations require upgrades to the existing Tomahawk Creek Facility to improve water quality in Indian Creek and downstream waters.

  2. The cost to continue sending flow and paying Kansas City, Missouri for treatment will substantially increase because of Kansas City’s $4.5 billion planned infrastructure improvements over the next several decades.  An evaluation determined that an upgrade and expansion would be a lower cost option in the long-term. 


What will this do to rates overtime? 

Residential customers’ rates are the same throughout the County, regardless of which Facility serves them.  Over the next several years, rates will increase 7-8% annually to cover the costs of sending flow to KCMO and for treatment throughout the County.  Johnson County Wastewater residential customers pay for wastewater based upon their winter average water usage.  The average residential customer pays $35 per month for wastewater service.  With all factors including the Tomahawk Facility, rates will increase by $2 per month for the average customer.  After the Facility is constructed, rates are projected to increase 3-5% annually to cover the costs for maintaining and operating all the pump stations, collection systems, and treatment facilities across the County.


How was the decision for expansion determined?

We conducted a study in 2010 of three options: 

  1. Expand the Facility to 19 (MGD) million gallons per day;

  2. Upgrade the Facility to 10 MGD and send 9 MGD to KCMO;

  3. Send all flow to KCMO.  

For each option, the capital costs to build the improvements and the operations and maintenance costs were included.  The costs were converted to net present worth over 25 years to compare them in today’s dollars.  The following were the cost comparisons:

Option 1: $470 million for expansion of the Facility to 19 (MGD) million gallons per day;

Option 2: $543 million for upgrade the Facility to 10 MGD and send 9 MGD to KCMO;  

Option 3: $759 million to send all flow to KCMO. 


Expanding the Facility is $73 million less than the second least expensive option.


What are the savings to ratepayers?

The estimated 35-year total savings is $785 million in favor of expanding the existing Facility to 19 MGD versus developing a 10 MGD Facility with the remaining flow going to KCMO.​


How much money is needed to build the expansion?

The total cost, including construction and other construction phase services, to expand the Tomahawk Creek Facility to treat all flow is $306,678,678.  As previous studies have shown, this is the most cost-effective long-term solution for County.  Bonds will be issued to fund the project and the debt service will be paid back over time.


Is it cheaper to send wastewater to Kansas City, Missouri?

No.  Johnson County Wastewater and its’ ratepayers are paying Kansas City, Missouri 2-3 times what it costs to treat wastewater at wastewater treatment facilities throughout the County.​


Is 19 MGD enough to handle future development? 

Yes.  A complete build-out estimate was conducted to determine the right size for the treatment Facility.


How long will the Facility be under construction?

The construction schedule start is April 2018.  Major work at the treatment Facility is expected to be completed by mid-2022.  Commissioning and startup will take place in the fall of 2021 and will extend into 2022.

What should the residents expect to see during construction?

During construction, a security fence will be set up around the site along Lee Blvd. as well as around the soccer fields north of the site.  Residents can expect to see tower cranes rising above the fence, as well as a temporary parking lot for workers in the southeast corner of the Lee Blvd. and Mission Rd. intersection.  Barricades will be placed at the locations where the bike path will be re-routed during construction.


Will you demolish the existing Facility?

A majority of the facilities were built in the 1950/60’s and will be demolished because of age and/or because they are not sized properly based on current standards and future flows.  Two of the structures that will be reused are the Influent Pump Station, which is the building located along Lee Blvd. and the Digester Complex which are closer to Mission and College.


How will construction impact me?

While there will be a lot of activity at the project site over the next four years, the majority of the work will be contained within the footprint of the existing Facility.  One of the earliest work items that will occur is the erection of a temporary fence that surrounds the project site as well as a portion of Indian Creek Trail. The trail along Lee Blvd. will be closed from April 2018 through mid-2022 but there is a detour path around the south side of the Facility.  Signs have been installed along the trail to help show you the detour path. 


Lee Blvd. will be closed for a few weeks during 2020 which improvements are made to elevate the road from Mission to the Facility Entrance above the 100-year flood elevation.  Check back on the website for construction updates. 

The T-ball fields along with a portion of the nearby parking will remain open to residents throughout construction.  The other portion of the parking lot will be designated for contractor parking and the soccer fields will be used for storing construction materials.  


This is a major project with a lot of moving pieces, a tight construction site, and a short duration for such a complex project.  While a majority of work will occur during daytime hours, it is inevitable that early morning work hours will be needed.  The team is very aware of the impact this could have to residents and will work to mitigate and reduce disturbances during these work efforts. 


How much bigger is the proposed foot print?

The footprint of the proposed facilities is approximately 30% greater than the footprint of the existing facilities.


How many workers are expected to be onsite?

The number of workers will change over the course of the construction from 25 during the start of construction to a maximum of 450 during its peak in 2019.  The contractor will work with subcontractors to develop creative ways to reduce car traffic to the site. 


Will trucks be driving through the neighborhoods?

A designated truck route will be developed for concrete and material deliveries to the Facility along State Line Rd., College Blvd., and Mission Rd., once a permanent traffic signal has been installed at the Lee Blvd. and Mission Rd. intersection.  The plan is to keep major truck traffic south of the Lee Blvd. and Mission Rd. intersection.



What about odor control?

The existing technology is from 1950’s/60’s when odor control technology wasn’t available.  Over the years, we have retrofitted odor control into the Facility.  New technologies will be installed to provide a more complete odor control system.

Is the new technology used by others in the region? 

The main treatment process is a 5-stage biological nutrient removal (BNR) process.  This is a proven, state of the art technology.  The City of Olathe is successfully operating the Cedar Creek Wastewater Treatment Plant with this technology.



What about screening?

The wooded areas on the west and south sides along Tomahawk Creek will be maintained.  Collaborative efforts between Johnson County Wastewater and the City of Leawood to improve landscaping, primarily on the north, are ongoing.  


What about replacing trees that are removed?

Johnson County Wastewater will work with the City of Leawood’s arborist on replacing some important tree species.

Can you make the outfall look better?

A natural-looking rock water cascade can be created at the confluence of the mitigation channel and the creek.  The pipe would discharge into the mitigation channel and minimize the potential for trail walkers to see it. 

What are the concerns with ammonia, nitrogen, and phosphorus?

Environmental Protection Agency and Kansas Department of Health and Environment are requiring stricter limits on our discharge for things such as ammonia, nitrogen, and phosphorus.  Ammonia is toxic to aquatic life in the receiving stream and this Facility will be required to maintain very low concentrations of ammonia year round. Nitrogen and phosphorus are both nutrients and when discharged in abundance can contribute to large algae blooms which reduce water quality and can ultimately lead to decreases in dissolved oxygen which harm aquatic life.



How will the Facility expansion impact flooding? 
  • Flooding will not be increased by expansion.  

  • The site will be raised up out of floodplain. 

  • A portion of Lee Blvd. will be raised above the 100-year flood elevation to access the Facility during flooding conditions.   

  • A vegetated channel will be built for natural flood control and the site layout will be compact so it won’t cause increased flooding levels.  

  • Because this is a regulated channel, the City of Leawood and Johnson County Wastewater have been working closely to ensure all floodplain regulations and requirements will be met.  


This site floods regularly and did so during July and August of 2017. Will the new site be susceptible to flooding?

Flooding will not be increased by expansion.  The site will be raised up out of the floodplain. A portion of Lee Blvd. will be raised above the 100-year flood elevation to access the Facility during flooding conditions.   

Because you are raising the site, will this cause other surrounding areas to see higher flood levels during severe storm events?

A vegetated channel will be built for natural flood control and the site layout will be compact so it will not cause increased flooding levels.  The City of Leawood and Johnson County Wastewater have been working closely to ensure all floodplain regulations and requirements are met because this is a regulated channel.

Traffic and Noise


Will there be traffic detours and/or closings?

The team is working to keep traffic disruption to a minimum; however, there will be some rerouting and closures during the construction phases.  There will be signs posted along the roads in addition to current traffic routes provided on the project website.  The team is working with the City of Leawood to make sure all construction traffic is minimized and kept to specified routes. 


Will traffic be an issue along Mission Rd or Lee Blvd?  
  • Traffic on Lee Blvd. will be maintained, but there will be intermittent road detours. 

  • Daily construction traffic will be crossing Lee Blvd. to the staging area, located in place of the soccer fields.  A 4-way stop will be set up there for the duration of construction.  

  • Contractor will make the necessary improvements to Lee Blvd. because of the heavy truck use during construction.  

  • All City of Leawood construction ordinances will be obeyed. There will be posted signs along with current traffic routes posted on the project website.

  • A plan is in development with the City of Leawood to install a permanent traffic signal at the intersection of Mission Rd. and Lee Blvd.  This traffic signal will help to provide a safe and orderly means for all traffic to enter and exit off of Lee Blvd.  The traffic signal is expected to be installed in the end of 2018 when construction related traffic begins to increase.

What is noise level during construction? 

All City of Leawood noise ordinances will be observed. 

What about Trail Closure?

A portion of the Indian Creek Bicycle and Pedestrian Trail that runs north of the Facility will be temporarily closed from April 2018 to the fall of 2021.  Trail users will be able to traverse this area by utilizing an existing trail that runs south of the Facility. Trail status signs will be posted at access points along the route with maps designating open and closed trails.


What is the construction schedule?

The construction schedule is from April 2018 - to mid-2022. 


Will plant operate during construction?

To keep it operating, it would take at least 5 years to construct, so the decision was made to divert all flow to Kansas City, MO during construction and reduce the duration of construction by 18 to 24 months.


Where are you sending flow during shut down?

Once construction is ready to start, all the flow will be sent to Kansas City, Missouri until the new facilities can be placed into operation. 


Can the Facility still send flow to Kansas City, Missouri in the future if there is a major disaster?

The large pipe that connects us to Kansas City, Missouri will remain.  The ability to send flow to Kansas City, Missouri will be retained in the event of any extreme emergency that requires such action.  The Facility was designed with backup equipment, processes, and redundancy; therefore, we do not anticipate ever having to send flow to Kansas City under typical dry and wet weather conditions.


Will there be work on the weekends?

In general, construction activities will be working within the City of Leawood’s hours of operation.  This states that no construction be allowed between the hours of 9:00 pm to 6:00 am, and not on Sundays, May 1st to September 1st.  No construction shall be allowed between the hours of 9:00 pm and 7:00 am, and not on Sundays, the remainder of the year. 

However, there will be times when the nature of the work necessitates working outside these stated working hours.  Examples of such work are 24/7 bypass pumping, critical connections, emergency work, etc.  During these events, we will post a notice on the homepage of the website to inform the public of the activity and duration.

Electrical Substation


Why is there an electrical substation onsite?

Early in design, the team began work with KCP&L. Upgrading from the current treatment technology which treats only 40% of the received flow to a modern system treating 100% flow created a significant increase in electrical demand.  An onsite substation was selected for the Facility for the following three reasons: 

  1. It would cause the least disruption to residents and neighborhoods as the work can be performed onsite.  Other options investigated would have required new circuits and infrastructure through existing neighborhoods. 

  2. The substation uses KPCL’s existing transmission lines which currently pass over the site. 

  3. The cost for a substation was the lowest of the alternatives considered.

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