History & Background
The Sewer Overflow Challenge
The Louisville Metro combined sewer system was built from the 1860s to the 1950s. The Louisville-Jefferson County Metropolitan Sewer District was founded in 1946 by the Kentucky State Legislature. However, our sewer system dates back to the 19th Century, and many of the original sewers are still in use. Today, we serve 220,000 customer accounts and 693,000 people. We operate and maintain:
- 6 regional water quality treatment centers
- 19 small water quality treatment center
- 304 pumping stations and 3,200 miles of sewers
- The Ohio River Flood Protection System, including 16 flood pumping stations and 29 miles of floodwall
Many older U.S. cities built combined sewers to remove both wastewater and stormwater from areas where people lived. Combining wastewater and stormwater in a single pipe and designing the system to overflow during periods of heavy rainfall was considered state-of-the-art wastewater technology in the late 19th and early 20th centuries. It was not until the late 20th Century that experts began to realize that combined sewer overflows (CSOs) were contributing a sizeable amount of pollution to urban streams and rivers.
In areas of Louisville Metro with separate sanitary sewers, sanitary sewer overflows (SSOs) occur because of aged pipes that leak when the system is overloaded from rainfall or due to illicit connections of sump pumps, roof drains and foundation drains to the sanitary sewer system.
The objectives of MSD's ongoing capital improvement program are to:
- Improve water quality and Reduce SSOs
- Implement a long-term CSO control plan
- Address neighborhood drainage deficiencies, and
- Upgrade the flood protection system
Meeting the Challenge
MSD initiated a Wet Weather Abatement Program in 1989. The first goal was to accurately identify potential overflow points in the combined sewers (CSOs) and in the fast growing sanitary sewer system (SSOs). Both CSOs and SSOs occur most often during prolonged rain storms. On the wettest days, millions of gallons of diluted sewage is discharged to our streams. MSD's Wet Weather Abatement plan includes these measures:
- Adding storage basins to the combined sewer system
- Cleaning sewers of excess sand, gravel and mud to increase carrying capacity
- Removing unnecessary clean-water connections (downspouts and sump pumps)
- Repairing sewer leaks that allow groundwater into the sewer system
- Informing the public about hazards associated with overflows
Accomplishments to date
MSD has already completed more than $1.4 billion in capital expansion and upgrades to wastewater and stormwater facilities.
- Sewer overflow points in the combined and separate systems have been reduced by 300
- Solids and floatable controls have been installed at 90% of CSO locations
- 66,000 linear feet of combined sewers have been separated
- 40,000 septic tanks have been eliminated
- 275 small plants and pumping stations have been eliminated
- Hundreds of small stations have been rebuilt and/or expanded to serve larger service areas
- Water quality treatment centers have been built and expanded to provide better treatment of wastewater from homes, businesses, and industries
Still, we continue to face challenges from sanitary and combined sewer overflows, especially during wet weather.