The new and expanded East Wastewater Treatment Plant in Evansville, IN, began operation in May 2023. PENETRON ADMIX SB, a crystalline waterproofing admixture, was used to protect key concrete components from the aggressive environment of the effluent – and extend the service life of the new higher-capacity plant.
The Evansville Water and Sewer Utility (EWSU) provides drinking water and sewer treatment services to Evansville, a community of about 118,000 and the largest city in Southern Indiana. The EWSU replaced the previous wastewater treatment plant, originally built in the 1890s and updated numerous times (increasing treatment capacity from 1.8 million gal/day (MGD) to about 23.5 MGD) prior to the latest expansion.
Located on the southern state border with Kentucky, the East WWTP discharges treated effluent into the Ohio River. The plant provided screening and grit removal, primary treatment, secondary treatment (using activated sludge), and disinfection. However, the secondary treatment capacity of the East WWTP was limited to 18.0 MGD, while the primary treatment capacity was 34.6 MGD. This was an insufficient capacity to prevent recurring combined sewer overflows (CSOs), when peak storm events overwhelm sewer capacities, resulting in both rainwater runoff and untreated sewage being released into the environment.
Complying with Clean Water Act Guidelines
This most recent wastewater treatment plant (WWTP) upgrade is part of the “Renew Evansville” project, a comprehensive state and federal mandate for the City of Evansville to comply with the Clean Water Act guidelines. Compliance requirements included reducing sewage overflows and implementing upgrades to the East Wastewater Treatment Plant, which meant providing full secondary treatment for peak flows up to 40 MGD. Completion of the Renew Evansville enhancements will allow EWSU to capture 98% of that flow, significantly reducing the amount of CSOs that would enter the Ohio River.
The $107 million of wastewater treatment plant (WWTP) modifications budgeted within the Renew Evansville program was used to expand capacity for the city’s West WWTP to 45 MDG (already completed), and the proscribed 40 MGD for the East WWTP. The construction project was designed by the structural engineering team at Hafer and built by Kokosing Industrial.
Expanding Treatment Capacity to 40 MGD
The East WWTP project included construction of separate stormwater and sanitary sewer pipes, expansion of sanitary sewer capacity to accommodate 10-year storm precipitation levels, and a CSO treatment facility designed to provide primary treatment (physical settling of solids), disinfection (chlorination), and dechlorination of CSOs, with the expanded – and required – 40 MGD treatment capacity.
“The East facility required a robust and waterproof concrete mix for both the ready-mix concrete and pre-cast concrete elements used in the new plant design,” adds Christopher Chen, Director of the Penetron Group.
PENETRON ADMIX SB, a cementitious crystalline waterproofing admixture, was specified by imi, the project’s ready-mix concrete supplier, for the headworks structure, grit chamber, treatment and clarifier structures, and disinfection system of the new WWTP.
Enhancing Concrete Service Life
Continually exposed to chlorides, sulfates, nitrates, disinfectants, and an array of corrosive compounds and chemicals encountered in a WWTP, concrete structures need a robust waterproofing treatment to withstand the aggressive environment. Delivered in pre-measured soluble bags to simplify the batching process, PENETRON ADMIX SB added to the concrete mix reduces concrete permeability, increases chemical resistance, and enables the self-sealing of any new or future hairline cracks. This enhances the durability and extends the service life of the treated concrete components.
“Penetron has collaborated with imi in a large number of wastewater treatment plant projects across the USA. Combined with our on-site support, the engineers at Hafer were confident of success,” concludes Christopher Chen.
A “Renew Evansville” project specifies Penetron: The expanded East wastewater treatment plant can now treat up to 40 MGD to better comply with Clean Water Act guidelines.
Pouring a robust and waterproof concrete mix: PENETRON ADMIX-treated concrete was used for both the ready-mix concrete and pre-cast elements of the expanded and upgraded East WWTP.
