The Metropolitan Sewer District has completed a new sewer overflow basin to capture sewage and stormwater that would otherwise pollute city waterways.

Roughly 110 million gallons of raw sewage and stormwater used to flow into Beargrass Creek every year, damaging the city’s natural resources, said MSD Engineering Director John Loechle.

“This is untreated sewage water, it’s diluted, but it’s still raw sewage that is going into the waterways that we use for recreation,” he said.

But that changed this week when the Metropolitan Sewer District unveiled the new Clifton Heights Combined Sewer Overflow Basin, which holds up to seven million gallons of waste and stormwater during storms.

“100-million gallons plus that used to go into the waterways now will stay in the system and once the rain stops and the system can take of itself, it will go to the treatment plant to be treated,” Loechle said.

Ryan Van Velzer | wfpl.org

Loechle said the basin is one of nine across the county, in addition to the Waterway Protection Tunnel, which will be four miles long and will hold enough sewage and stormwater to fill 83 Olympic swimming pools.

Capturing sewage overflows will become even more important in the coming decades as climate change brings warmer temperatures that increase the frequency of heavy storms.

The Clifton Heights basin is mostly underground, beneath a meadow that’s home to more than two dozen native plant species that provide pollinator habitat and erosion control.

In addition, contractors with MSD used rock excavated from the site as foundation for a pair of new parking lots at the Louisville VA medical center, Loechle said.

MSD expects to complete another sewage overflow basin in Portland in November.

Ryan Van Velzer is WFPL's Energy and Environment Reporter.