The $15.8 million expansion and update of the wastewater treatment plant in Mitchell, South Dakota, was completed in December 2022 – and provides the community with much-needed additional wastewater treatment capacity. PENETRON ADMIX SB, a crystalline concrete waterproofing admixture, was used to protect the concrete components from the aggressive environment due to the effluent – and extend the service life of the plant.
With a population of around 16,000, Mitchell is the county seat of Davison County, in southeastern South Dakota, and the state’s sixth largest city. An hour west of Sioux Falls and right off Interstate 90, Mitchell is also a popular stop for tourists on their way to the Black Hills, the Badlands, and Mount Rushmore. In addition to agriculture, a dominant industry in the region, the city boasts vibrant technology and healthcare sectors, as well as two higher education institutions: Dakota Wesleyan University and Mitchell Technical College.
“The town’s growing population and its aged wastewater treatment infrastructure brought up the need for a comprehensive update and expansion of the facility to increase wastewater treatment capacity,” says Christopher Chen, Director of The Penetron Group.
Constructed in 1970, Mitchell’s previous wastewater treatment plant had seen several repairs and improvements throughout its years of operation. However, an assessment of the facility’s structural condition and treatment processes presented by HDR Inc., a national engineering, architectural, and construction firm, recommended a thorough revision of the facility. As a result, the City of Mitchell’s project engineer stipulated that the headwaters, septage receiving station, and the treatment tanks of the new plant – all concrete structures exposed to the effluent – needed to be upgraded to ensure impermeability and enhanced durability.
“JD Concrete, a regional ready-mix concrete supplier and long-time Penetron partner, was asked to provide a mix design that met these requirements,” adds Christopher Chen. “The final mix included PENETRON ADMIX SB, a crystalline concrete waterproofing solution, which met all the specifications to effectively waterproof and protect the plant’s new concrete structures.”
Added to the concrete mix during the batching process, PENETRON ADMIX SB permanently reduces concrete permeability, and increases chemical resistance to the chlorides, sulfates, nitrates, disinfectants, various corrosive compounds, and the chemicals added during the plant’s treatment processes. It also enables the self-healing of any existing or future hairline cracks; this enhances durability and extends the service life of the treated concrete components.
Overall, PKG, the general contractor, and the project engineer were “extremely pleased” with the waterproofing capabilities of PENETRON ADMIX. The admixture’s green tracer, visible in the bleed water during concrete placement and finishing, also provided visible proof the crystalline waterproofing solution was truly in the mix. Finally, dosage was made simple by using 1 soluble bag per cubic yard of concrete.
“JD Concrete noted the Mitchell plant project went seamlessly,” adds Christopher Chen. “They look forward to using Penetron in the future!”