Sheboygan launches largest UV disinfection system
In 1887, a private company began pumping untreated Lake Michigan water to citizens of Sheboygan. The ornate brick building that housed the original steam pump still stands at 72 Park Avenue. Although at that time pumped water must have seemed a marvel, the lack of treatment resulted in aesthetic problems and the spread of water-borne disease including typhoid.
By 1922, the public Water Utility had been formed and began adding chlorine gas to disinfect the water. However, the water was not treated in any other way, resulting in great variations in water quality from day to day. In 1929, the Utility began construction of a complete water treatment plant, using pre-treatment and filtration processes to clarify the water.
During the intervening years, many changes took place as the city grew and increased its thirst. Changes took place in the water industry as well, including the recent advent of secondary disinfection barriers. These secondary barriers help protect against system failures by ensuring that water disinfection does not rely on one process. The most common barriers include ozone gas, membrane filtration and ultraviolet disinfection.
On Aug. 1, 2016, the Sheboygan Water Utility began operation of its ultraviolet disinfection facility – the largest in the state for drinking water. Ultraviolet, meaning beyond violet, is high-energy light that is invisible to the human eye, though we all know its effect on a sunny day at the beach. UV disinfection subjects water to high-intensity UV light that inactivates harmful microorganisms, including E. coli, cryptosporidium and giardia. The Utility determined that UV was the most cost-effective secondary barrier for its existing plant.
The Utility received a low-interest WDNR Safe Drinking Water loan to construct the $2.9 million project, which also qualified for $500,000 in principle forgiveness. Miron Construction was awarded the construction contract as the low bidder. CDM Smith and Donohue & Associates provided engineering services.
UV does not add any chemicals to the treatment process, which is one of its advantages. The Utility continues to use chlorine as its primary disinfectant and as its residual disinfectant in the water distribution system. This residual is necessary to protect against contamination in the many miles of water main pipes.
Due to limited space at the water treatment plant, the UV facility was squeezed into tight quarters between the low-lift pumping station and Lake Michigan. The contractor had to work around critical pipelines during the excavation and tie-in process. Despite the high level of risk, knowledgeable Utility staff minimized the impact of the project on the water treatment plant. In one case, construction vibration caused an older water pipe to start leaking, but Utility staff were able to remedy the issue in short order.
Other problems included leaks at a concrete tank and mechanical difficulties with the UV bulb sleeve cleaning mechanism. The Utility has been working with the contractor to resolve these issues.
With the UV disinfection system, the Sheboygan Board of Water Commissioners has again shown their commitment to prudent investment in infrastructure that benefits Utility customers, while at the same time maintaining competitive water rates for the community. Despite the additional loan for the project, the Utility maintains some of the lowest water rates in the state.
Joe Trueblood is the Water Utility superintendent in the City of Sheboygan. Various city leaders and department heads are taking over the "A View from City Hall" weekly column during the mayoral race.