Under the Great Lawn in Shawnee Park, sits the MSD Shawnee Park Combined Sewer Overflow (CSO) Basin. The top of the basin is approximately 12 feet below grade, with three-foot-thick reinforced concrete walls. When it rains, the basin is hard at work protecting the Ohio River, the Park and the neighborhood from combined sewer overflows.
On Friday, June 21, MSD joined Mayor Greg Fischer and Shawnee Park neighbors to celebrate the end of more than two years of construction work on the basin.
How it works
Rainwater enters the combined sewer system through stormwater pipes and catch basins. This added water can overwhelm the sewer system sending a combination of wastewater and rainwater into the Ohio River.
The Shawnee Park CSO Basin is a sealed, watertight concrete structure that captures and stores 20 million gallons of wastewater and stormwater during rain events and gradually release it back into the sewer system when treatment capacity is available. The mixture of rainwater and wastewater then flows through the sewer system to MSD’s Morris Forman Water Quality Treatment Center for proper treatment and release into the Ohio River. When the basin is empty, water is flushed across the structure floor to clean any remaining debris.
The big picture
The $78 million Shawnee Park CSO Basin is part of a $1.15 billion mandate from the U.S. Environmental Protection Agency to clean up local waterways. The Shawnee Park Basin is the largest of 10 underground
CSO basins. The basins and the 4-mile long Waterway Protection Tunnel will work together to greatly reduce combined sewer overflows by the end of 2020.
Underground storage is part of MSD’s endeavor to prevent wastewater from overflowing into Louisville’s waterways. MSD has recently completed—or is close to completing—the last four of ten basins.
• Logan Street CSO Basin, operational December 2017, complete;
• Clifton Heights CSO Basin, operational December 2018, wrapping up site work;
• Shawnee Park CSO Basin, operational March 2019, site work nearly complete; and
• Portland CSO Basin, operational date of November 2019, construction continues.
Construction of the Waterway Protection Tunnel is underway. The tunnel is expected to be operational by the end of 2020.