The Greenbush Combined Sewer Overflow (CSO) project in Lafayette, Indiana, was completed and certified in April 2019. Project contractor Bowen Engineering worked with IMI, the ready-mix supplier, to integrate PENETRON ADMIX as the all-important concrete waterproofing solution – a choice that led to an industry award.
Prior to the Clean Water Act, municipal sewer systems in the USA were designed to collect rainwater runoff, domestic sewage and industrial wastewater – all in the same pipe. During rainstorms, the sewer systems transport the combined wastewater directly to the wastewater treatment plant. These spikes in run-off often led to unwanted overflows during heavy storms.
"The storm overflows in Lafayette, combined with the raw sewage, would normally end up in the Wabash River,” says Christopher Chen, Director of The Penetron Group. “With the newly completed Greenbush facility, this overflow is now directed to the CSO tank during heavy rainstorms, where it is stored. Once the town’s collection system catches up, the overflow is pumped back into the system and sent to the Lafayette Waste Water Treatment Plant (WWTP), where the plant can now treat the wastewater. This will help to markedly improve the water quality of the Wabash River.”
The Greenbush CSO storage tank is massive: a 4.2 million-gallon below-grade covered concrete storage tank roughly the size of an NFL football field. It is over 350-feet (110 m) long, 109-feet (35 m) wide and has walls that are 35’ (10 m) tall and 3’ (1 m) thick. The tank is designed to hold a run-off event equivalent to a 100-year rainfall for the Lafayette area.
Extensive concrete mix design testing was carried out prior to construction by project coordinator Bowen Engineering and Irving Materials Inc. (IMI), the building materials supplier. The tests resulted in an optimal mix design to ensure the specified air content, slump, and workability that the finishing crews needed.
“Penetron has worked closely with Bowen Engineering and IMI on a number of similar wastewater projects in which the concrete mix properties and waterproofing performance parameters consistently met the project specifications,” adds Christopher Chen. “In the Greenbush project, PENETRON ADMIX was integrated into the mix to ensure that any cracks that formed in the structure would be self-healed and sealed – to maintain the integrity and functionality of the structure.”
In addition to the enormous slab and deck of the Greenbush CSO structure, the project consisted of poured walls, columns, a junction structure, and a building on the site that controls the electrical components of the storage tank. The slab and deck were poured in approximately 700 cubic yard pours and required a speedy 200 cubic yards of concrete to be delivered each hour to feed the two on-site concrete pumps that were placing the concrete. IMI project managers carefully planned the pour to allow the use of over 20 concrete mixers from two concrete plants to facilitate pours around the clock. This schedule enabled Bowen Engineering to reach their desired production rates – and keep to the tight construction schedule.
Ultimately, close to 10,000 cubic yards (7,645 m3) of concrete for the water containment structures were treated with PENETRON ADMIX.
IMI prefers PENETRON ADMIX due to the admixture’s consistent performance and the ease of dosing one pre-measured soluble bag per yard, which simplifies the mixing procedure. Bowen Engineering also uses PENETRON ADMIX for its performance and the ultraviolet green tracer that proves Penetron technology is “in the mix.”
“An added bonus for the Greenbush CSO project was announced after construction was completed; the project won the IRMCA 2019 Award as ‘an example of innovative engineering and project management,’” adds Christopher Chen. “The IRMCA Award was established by the Indiana Ready Mixed Concrete Association to recognize outstanding leadership and innovation in the ready mixed concrete industry in Indiana.”