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Design-build solution tames combined sewer overflow discharges

Concrete News
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The $78 million Southwestern Parkway Combined Sewer Overflow (CSO) Basin project, a component of Louisville and Jefferson County (Ky.) Metropolitan Sewer District’s federal Consent Decree to mitigate CSO discharges to local waterways, received the Design-Build Institute of America’s 2019 Best in Engineering Design Award and National Award of Excellence (Water/Wastewater) recognition.
PHOTOS: Brown and Caldwell, Lakewood, Colo.
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An underground basin of the Shawnee Park magnitude created daunting issues: Pouring large amounts of concrete efficiently during six- to eight-hour schedules; measures to eliminate honeycombing or cracking; and, ensuring proper concrete flow around reinforcing steel and wall ties. Allied Ready Mix used GCP Concera admixtures to yield control flow, segregation-resistant mixes. With a target 22-in. spread, the mixes came to a rest more quickly than self-consolidating varieties.

Located in Louisville’s Shawnee Park, part of the National Register of Historic Places-listed Olmsted Park System, the project consists of a large “capture and release” system to temporarily store CSOs during wet weather events and gradually return them to the collection system for treatment as capacity becomes available. Environmental engineer Brown and Caldwell drew up a plan encompassing a 20 million-gal. storage basin; associated washdown systems; 30 million-gal./day effluent pump station; CSO diversion structures; and, associated conveyance piping.

Preservation of Olmstedian design features in Shawnee Park, particularly the Great Lawn’s pastoral, undulating surface, made it vital that the project team deliver a facility virtually invisible to the public. Hence, the basin was constructed below the surface of the Great Lawn, with park topography concealing a walk-out operational access point.

The $60 million Shawnee Park Basin Project is part of a federal mandate to prevent wastewater from pouring into the Ohio River. The reinforced concrete roof of the watertight basin is 36 inches thick and supports 12 feet of soil harboring Great Lawn.

One of Indiana’s largest concrete contractors, Wilhelm Construction, was tasked with overseeing the concrete quality control for the project, including managing the mix design, temperature and testing. The enormity of the basin’s design required over 30,000 yd. of concrete from Allied Ready Mix Co., Louisville.

EPA COUNTDOWN

The U.S. Environmental Protection Agency has kicked off a year-long celebration leading up to the agency’s 50th anniversary, December 2, 2020. “Since the agency’s inception under the leadership of the late Administrator William Ruckelshaus, EPA staff have worked tirelessly to clean up our air, water, and land for the American people,” says Administrator Andrew Wheeler. “Together, we have achieved significant milestones in support of our mission to protect human health and the environment. I look forward to celebrating EPA’s accomplishments over the coming year and continuing to build on our progress for future generations.”

In the wake of elevated concern about environmental pollution, along with the launch of Earth Day in April 1970, EPA was established to consolidate into one agency a variety of federal environmental responsibilities including research, monitoring, standard setting, and enforcement activities to ensure environmental protection while simultaneously safeguarding human health. Inaugural Administrator Ruckelshaus took the oath of office two days into the new agency.

Over the last 50 years, the agency has worked to fulfill its mission of protecting human health and the environment by improving the nation’s air, cleaning up land and water resources, and providing a cleaner, healthier environment for all people. Among major agency accomplishments:

  • Cleaner air. From 1970 to 2018, the combined emissions of the six criteria pollutants dropped by 74 percent, while the U.S. economy grew by 275 percent, Americans drove more miles, and population and energy use increased.
  • Purer water. In the early 1970s, more than 40 percent of the nation’s drinking water systems failed to meet even the most basic health standards. Today, more than 92 percent of community water systems meet all health-based standards.
  • Cleaner land. Throughout the history of EPA’s Brownfields program, which aims to clean up and sustainably reuse contaminated properties, local communities have been able to use grants to leverage 150,120 jobs and more than $28 billion of public and private funding.