Containing CSOs in Kentucky

The Rowan Pump Station is the deepest submersible pump station in Kentucky. 

By Brian Alvarado

Located in Louisville, Ky., the Rowan Pump Station serves as the Louisville-Jefferson County Metropolitan Sewer Districts (MSW) response to a consent decree limiting the quantity of combined sewer overflows (CSOs). The Rowan Pump Station is the deepest submersible pump station in Kentucky and one of a few that are operational around the country. With a cost of $37 million, it is the only visible portion of the massive Waterway Protection Tunnel, which is a 4-mile underground tunnel that will prevent 439 million gallons of rainwater and wastewater from overflowing and polluting the Ohio River on an annual basis. The tunnel will store the rainwater and sewage mixture until capacity is available in the sewer and treatment systems.

“The 220-foot-deep shaft houses 10 large pumps, each capable of moving 5 million gallons per day — enough capacity to empty the tunnel in just over a day,” said Wastewater Project Principal Mike Rudisell of HDR. “Above ground, the pump station doubles as a stunning architectural feature that enhances the planned expansion of Waterfront Park Phase IV.”

To bring the station to life, the team consisted of HDR as the engineer, Pace Contracting, LLC as the builder and the Louisville and Jefferson County Metropolitan Sewer District, which owns it. 

“The Rowan Pump Station team consisted of a knowledgeable owner, dedicated consultants, designers, inspectors and scientists committed to the goal of developing a cost-effective solution that would simplify operation, minimize maintenance and provide the community with a lasting aesthetic impact,” Rudisell said.

Digging Deep

For the Rowan Pump Station development team, one key obstacle to overcome was digging a 220-foot-deep hole for the project. To do so, the team had to install 54 four-foot-diameter overlapping secant piles around the circumference of the shaft through the soil and keyed five feet into the rock surface and excavated through 50 feet of soil to reach the rock surface. Additionally, the team would then transition to explosive charges to blast the rock downward.

“The team would blast twice a week, which would create about 10 feet of depth per blast,” Rudisell said. “Sand, rubber mats and a special shaft cover muffled the blasts, reducing the noise and vibration to less than normal vehicular traffic. The team then excavated loose rocks within the shaft and the process repeated.”

Following excavation, the team lined the pump station shaft with structural concrete. Due to its thickness being greater than 3 feet, these concrete pours were classified as mass concrete. It is critical to control the temperature of mass concrete as excessive heat of hydration can cause concrete cracking and failure during the curing process. 

The team implemented special measures and coordinated with concrete suppliers to deliver concrete with ice and mixtures to control temperatures. They also installed thermal sensors with remote monitoring capabilities to record temperature data during placement and curing.

The project’s nature promotes and supports safe, clean waterways in the region and will contribute to economic, social and environmental benefits.” – Mike Rudisell, Wastewater Project Principal, HDR

During placement, the contractor used custom circular forms to facilitate concrete lifts. They installed and tied reinforcing steel, poured concrete into 10-foot-tall lifts, and moved the form work upward toward grade. The team completed two to three lifts per week on average.

Reduced River Pollution and Runoff

The project also took into consideration its environmental surroundings, especially the Ohio River. The Ohio River is home to more than 150 species of fish and 40% of North America’s freshwater mussel species, according to Rudisell. It supports about 27 million people with drinking water, jobs and recreational opportunities. However, the Ohio River is consistently ranked as one of the United States’ most polluted waterways.

“The Waterway Protection Tunnel project reduces CSOs from 25 locations along the Ohio River, diverting them to the tunnel storage and pumping system,” Rudisell said. “This will prevent approximately 439 million gallons of CSO from entering the river each year.”

The new pump station features a bioswale to capture and treat stormwater runoff from the building roof and parking lot before it enters the collection system. 

“The project’s nature promotes and supports safe, clean waterways in the region and will contribute to economic, social and environmental benefits,” Rudisell said.

Attractive Architectural Appearance

The building exterior and site features a “softer” side to integrate with Waterfront Development Corporation’s Waterfront Park Phase IV expansion, according to Rudisell. Phase IV expands the park westward along the Ohio River and connects the downtown core with West Louisville. The new pump station links the various park zones through orientation, materials, lighting and geometry. 

“The aesthetic design integrates the poetic relationship of the city to the river,” Rudisell said. “The building’s visual presence shifts visually. By day, it exhibits solid elements within the landscape. By night, it transforms into a semi-transparent glowing lantern with various color shows and patterns.”

The river shimmers as the sun sets over it, and the design harkens to a “Fresnel lens” — a type of lens with a distinct corrugation pattern that emits a small portion of light into the most efficient pattern possible — commonly used in lanterns. 

“The pump station is a lantern along the river,” Rudisell said. 

Positive Public Perception

Throughout the project, the team sought input from the public. With the integral placement within the Waterfront Park Phase IV Expansion, the public will see not just a pump station building, but a structure that will become an interaction point within the landscape of the park. 

“MSD’s transition from storage tanks to a tunnel was also influenced by the public’s desire to have these structures hidden below ground,” Rudisell said.

The project also benefited the public economically, as the contractor exceeded the local labor participation goal of 90% for compliance with MSD’s program. A majority of the labor force for the Rowan Pump Station project lived in Jefferson County, thus creating new jobs in Louisville and bringing additional skilled trades and workers to the region.

Additionally, it’s MSD’s goal that the job site will evolve into a play site for the community as well.

“We wanted our structure there to be functional on the inside to take care of our wastewater pumping needs, but also attractive on the outside to be worthy of being part of a world-class public park like we have in Waterfront Park,” Rudisell said.

Aspiration For Others

The development team of the Rowan Pump Station views the project as one that can teach many lessons that can be valuable to other engineers considering alternatives for deep pumping applications.

“As the design lead and project manager, I feel very fortunate that I was given this opportunity to deliver one of the most unique projects in the country,” Rudisell said. “This project is certainly a great example of Louisville MSD’s commitment to safe, clean waterways.”

The HDR team continues to innovate and integrate new methods into other pump station projects, using the Rowan Pump Station as a blueprint.

“Our HDR team is currently designing a similar pump station and conveyance system for wet weather attenuation to prevent sewer overflows for Clean Water Nashville,” Rudisell said. “The current concept includes a deep submersible pump station with a capacity of 100 MGD.”

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Brian Alvarado is the editor for American Infrastructure Magazine. He can be reached at brian@builder.media.

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