Louisville, KY
Completed in 2019
The Clifton Heights Combined Sewer Overflow (CSO) Basin is an infrastructure project designed to provide 7 million gallons of stormwater storage, significantly reducing combined sewer overflows into the Ohio River and supporting Louisville MSD’s EPA Consent Decree requirements.
The project required deep excavation, complex reinforced concrete construction, mechanical system integration, and construction within a regulated floodplain environment – all executed under demanding site and environmental constraints.
Impact & Purpose
The basin now serves as a critical component of the region’s long-term water quality improvement strategy.
- Constructed a 7-million-gallon storage basin to reduce combined sewer overflows
- Supported compliance with EPA Consent Decree requirements
- Improved long-term regional water quality
- Strengthened Louisville’s wastewater infrastructure resiliency
Project Scope
The facility temporarily stores storm flows and pumps them back into the treatment system following storm events.
- Excavation of a 300’ x 150’ basin approximately 45 feet deep
- Removal of more than 70,000 cubic yards of soil and rock
- Placement of over 18,000 cubic yards of reinforced concrete
- Installation of 6.3 million pounds of reinforcing steel
- Construction of integral pump station and mechanical process systems
- Influent and effluent piping systems
- Elevated top slab supported by 75 cast-in-place concrete columns
Technical Complexity
Construction occurred within a floodplain at the base of a U.S. Army Corps of Engineers floodwall, presenting significant access and environmental constraints. A historic Ohio River flood in 2018 completely inundated the site during construction, necessitating full site recovery and remobilization. Despite this significant event, the project was delivered within schedule parameters.
A value-engineered solution redirected excess excavated material to a nearby VA hospital, creating a stable embankment for a new parking lot expansion while reducing haul and disposal impacts.
Key complexities included:
- Deep excavation required removal of approximately 50 feet of rock to reach an 80-foot depth within 50 feet of a historic 1904 structure. Work was executed with precise control measures to protect adjacent infrastructure, resulting in zero impact or structural disturbance.
- Limited site access and logistical coordination
- Implementation of a single-sided wall forming system with rock anchors, reducing excavation quantities and eliminating flowable fill backfill
- Complex falsework and sequencing for elevated top slab construction
- Coordination of 127 subcontractors and suppliers
- Compliance with aggressive local labor participation goals
- Implementation of confined
