With construction completed by February 2024, the commissioning of the new lift station increases reliability and capacity of the sewage system upgrade in Columbia, Missouri – as set out by the Columbia Wastewater and Stormwater Integrated Management Plan. Penetron’s antimicrobial concrete admixture and PENETRON ADMIX SB, a crystalline waterproofing admixture, provided the needed concrete protection from microbially-induced corrosion of the new infrastructure.
With a population of about 128,000, Columbia is the fourth largest and fastest growing city in Missouri. Located near the geographic center of the state, it was originally known as an agricultural town. Today, it is a center of learning as the home to Stephens College (1833), the University of Missouri (1839), and Columbia College (1851).
The city is situated among forested hills and rolling prairies near the Missouri River Valley. The area’s limestone bluffs and glades feature many caves and springs that water the Hinkson, Roche Perche, and Bonne Femme creeks that flow through the town. Columbia manages its wastewater with a separate sanitary sewer system that transports sewage to the city’s wastewater treatment facility; the treated effluent is discharged to the Eagle Bluffs Conservation Area, a large wetland area that drains into the Missouri River. The city also operates a storm sewer system (jointly with Boone County and the University of Missouri), which discharges to Missouri River tributaries, including Hinkson Creek, which runs through Columbia and features several trails and parks along its shores.
“During heavy storms, stormwater and groundwater would enter Columbia’s sanitary sewer system through cracks and improper connections, resulting in sanitary sewer overflows (SSOs) that discharged untreated sewage into the city’s waterways, and also caused sewage to back up into basements,” explains Pat O’Brien, Regional Sales Manager for Penetron USA. “After both state and federal environmental agencies set new pollution guidelines, the wastewater treatment facility was expanded and upgraded to comply with the limits.”
More recently, the Columbia Wastewater and Stormwater Integrated Management Plan mandated the replacement of the sewer system’s malfunctioning lift station as well as further sewer system improvements (such as: rehabilitation of existing infrastructure and addition of new pipelines and manholes).
“A new, higher capacity lift station was engineered to replace the previous faulty structure,” adds Pat O’Brien. “According to the project engineer, this massive, below-grade concrete structure, which is designed to run 24/7, 365 days a year, required a proven and durable solution to counter the threat of microbially induced corrosion (MIC), a common source of deterioration of concrete pump stations.”
Increasingly recognized as a potent threat to exposed 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, which is found in sewage and septic environments, converts the hydrogen sulfide gas (H2S) into biogenic sulfuric acid (H2SO4). The presence of biogenic 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 bacterial growth on and in concrete consistently stops the formation of biogenic sulfuric acid, preventing damage caused by MIC.
Parker Dungan, the ready-mix concrete supplier, added Penetron’s antimicrobial admixture and PENETRON ADMIX SB, a crystalline waterproofing admixture, to the concrete mix for all concrete elements of the lift station, gravity main, and connection points with existing force mains. PENETRON ADMIX SB was added to the concrete to waterproof the concrete and also provide much needed reinforcing corrosion mitigation to increase the service life of the concrete by decreasing the permeability of the concrete and considerably slowing down the aging of the concrete.
“Identical to PENETRON ADMIX SB, the antimicrobial properties of Penetron’s specialized admixture are permanent,” adds Pat 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.”
