Completed in August 2023, the new pump station in North Aurora, Illinois, provides increased reliability and capacity for the sanitary sewer system needed by the Fox Metro Water Reclamation District in northeastern Illinois. Penetron’s antimicrobial concrete admixture and PENETRON ADMIX SB, a crystalline waterproofing admixture, provided crucial concrete protection from microbially-induced corrosion for the new facility.
Only 40 minutes southwest of Chicago, the town of North Aurora has a population of around 19,000. Located along the scenic Fox River, the area’s largest industries are manufacturing, education, and healthcare.
A critical part of the region’s public utility infrastructure, the original North Aurora pump station was built in the 1960s and due to increasingly frequent repairs and maintenance, was nearing the end of its service life. It was designed to collect and lift untreated sewage in a pressurized main from below the Fox River to the gravity North Aurora interceptor many feet in elevation above the influent sewer. It provided service to 8,000 residents of North Aurora and over 14,500 residents of Kane and DuPage counties.
Construction of the replacement North Aurora Pump Station was a $9.8 million project designed by Strand Associates, a national engineering firm specialized in civic infrastructure. The new 32 million-gallon per day drywell submersible pump station comprises force mains (approximately 45 feet of 36-inch-diameter and 75 feet of 24-inch-diameter) between the new pumping station and connection points with existing force mains, and approximately 275 feet of a 42-inch-diameter gravity sewer to lift sewage flows approximately 65 feet (20 m) from the Fox River inverted siphon chamber to the North Aurora gravity interception sewer.
“The construction included a three-level below-grade concrete structure that would be in operation 24/7, all year round,” adds Patrick O’Brien, Regional Sales Manager for Penetron USA. “The project engineer required a proven and durable solution to counter the threat of microbially induced corrosion (MIC) of the new concrete pump station.”
Less well-known than many other threats to concrete structures, MIC is a serious challenge that can rapidly compromise and disable the concrete structures of wastewater and sewage system infrastructure. The thiobacillus bacteria, also known as acid-producing bacteria found in sewage and septic environments, converts the hydrogen sulfide gas (H2S) into biogenic sulfuric acid (H2SO4). The presence of sulfuric acid on concrete surfaces can unleash highly localized and rapid corrosion processes that eat away the cement paste of the concrete matrix. This, in turn, quickly exposes the embedded reinforcement steel of underground concrete sewage systems to water, oxygen, CO2, and chlorides – resulting in catastrophic corrosion related failures in the concrete.
Penetron’s antimicrobial admixture prevents microbial-induced corrosion (MIC) by using an electro-physical mechanism to destroy the cell walls of the thiobacillus bacteria on contact. Eliminating the bacterial growth on and in concrete consistently stops the formation of biogenic sulfuric acid, avoiding the damage caused by MIC.
Narvick Brothers Ready Mix Concrete added Penetron’s antimicrobial admixture and crystalline waterproofing admixture, PENETRON ADMIX SB, to the concrete mix for all concrete elements of the pump station, connection points with existing force mains, and the final gravity sewer line. PENETRON ADMIX SB was added to the concrete to not only waterproof the concrete but also provide much needed reinforcing corrosion mitigation and increase the service life of the concrete by substantially slowing the aging of the concrete.
“Identical to the well-known PENETRON ADMIX, a crystalline concrete waterproofing admixture, the antimicrobial properties of this specialized admixture are permanent,” explains Patrick O’Brien. “Once added to the mix, it becomes a permanent part of the concrete matrix and is leach resistant, even repeated contact with bacteria can not lessen the effectiveness of the admixture.”