STV supported the Louisville/Jefferson County Metropolitan Sewer District’s (MSD) Consent Decree program by providing geotechnical field exploration and construction observation for a 20-million-gallon, 449-foot x 207-foot x 49-foot underground combined sewer overflow (CSO) basin beneath Shawnee Park in Louisville, Kentucky. Designed to capture and store untreated wastewater and stormwater during wet weather events, the basin helps prevent overflow into the Ohio River. Once sewer system capacity is available, the stored water is pumped back for treatment before being released.
The structure includes a wet well, pump station, operations building and three CSO diversion structures. Built on a mat foundation with auger-cast piles for uplift resistance, the basin incorporates steel sheet pile walls with tie-back anchors for excavation support and cast-in-place concrete walls.
As part of its geotechnical field exploration services, STV supported seven soil test borings, rock coring and piezometer installation, along with laboratory testing for soil strength and permeability. The team also performed geotechnical analyses to assess seepage, lateral earth pressure, bearing capacity and buoyancy forces.
During construction, STV reviewed submittals for sheet pile wall designs, backfill modifications, compaction methods (flushing and jetting vs. vibratory compaction), pipe support bearing capacity and auger-cast pile installation. When voids formed due to sand washout through the sheet pile walls, STV conducted additional borings and coordinated grouting to stabilize the structures.
Now complete, the project is largely invisible to the public and enhances both the Ohio River’s water quality and the long-term sustainability of one of Louisville’s premier parks.
20M
gallon CSO basin
374
auger cast piles
21,000
cyds of concrete
