In Louisville, Kentucky, combined sewer overflow events near the historic Shawnee Park will soon be dramatically reduced. B&N designed the addition of a $75 million, 20-million-gallon underground storage basin that is expected to reduce the number of overflows per year from approximately 70 down to no more than eight under the design conditions.
In a design/build partnership with Ulliman Schutte, B&N completed the preliminary and final designs in less than one year to help the Louisville and Jefferson County Metropolitan Sewer District (MSD) meet an EPA consent decree and improve water quality in the Ohio River.
In the Event of a Storm
The Southwestern Parkway Combined Sewer Overflow (CSO) Basin project – now under construction – will be an underground, concrete storage facility that includes:
- A new 20.2-million-gallon-per-day pump station
- Diversion structures
- Conveyance piping and other related facilities.
B&N designed new diversion structures in and around existing sewer lines to direct the combined storm water and sewage overflow to the basin instead of discharging into the Ohio River during large storms.
The basin can be filled to various levels depending on the size of the storm event, then emptied once the storm is over. A pumping system sends the combined overflow to the closest Wastewater Treatment Plant once the storm ends. After the basin empties, a series of automatic wash down processes that includes flushing gates and tipping buckets are used to clean the basin.
In addition to the short timeframe for design, the Southwestern Parkway CSO Basin is being built in the middle of the historic Shawnee Park. The 100-year-old park site was selected because of its close proximity to the Ohio River and two large combined sewer outfalls. It also is the home to one of MSD’s existing flood protection pump stations.
The client and the community both wanted to preserve the park for future use. As a result, the design team was asked to preserve mature trees in the area and maintain access to the park during and after construction. In addition, the park area known as the “Great Lawn,” was to be restored to current conditions, with no protrusions from the basin below. In developing the design, B&N coordinated with MSD, Louisville Metro Parks, the Olmsted Parks Conservancy, the State Historic Preservation Office and the U.S. Corps of Engineers.
The buried basin design with a “walkout basement” for operator access allows the park grounds to continue to be used. The architectural elements maintain the historic park appearance and help the visible parts of the basin blend with the surroundings. B&N's scope included designing park facilities on top of the basin, including an open pavilion, interactive learning space, and new restrooms.
Construction on this progressive design/build project started in April 2017 and is scheduled for completion in 2019. B&N also designed two additional basin projects for MSD – the Fairmount Road Basin and the award-winning Buechel Basin project.