In the water distribution system, cold weather can create a risk that is hidden from view: ice accumulation inside water storage tanks. Often, when operators realize they have a problem with ice in their tanks, it is too late—the tank’s interior is damaged or the wall is punctured.
The Municipality of Brockton knew that their 70-foot-tall standpipe in Walkerton, Ontario was thermally stratified in the warm summer months. Not only was there a persistent band of condensation on the outside of the tank, and taste and odor complaints, the team was hit with a blast of hot air whenever they opened the tank hatch. Brockton looked into active mixing to help eliminate the thermal stratification in the tank.
Posttreatment aeration inside water storage tanks can be used as a cost-effective option to strip trihalomethanes from finished water. This paper explores how different design variables affect THM removal rates for diffused aeration and spray aeration systems.
South of Laramie Water and Sewer District in Wyoming was concerned about preventing ice damage in a 300,000-gal pedisphere tank. The utility decided to install a PAX Water Mixer (PWM100) - designed specifically for small tanks - to eliminate ice.
The City of Covina, California struggled to retain residual in a 5MG underground tank. After installing a PAX Water Mixer, Covina was able to eliminate manual dosing in the tank.
Across California and Nevada, implementation of the Stage 2 D/DBP Rule is spurring utilities to explore a range of strategies for improving water quality in their water systems.
Mixing in potable water storage tanks is increasingly recognized as an important factor in improving water quality and protecting tank assets. Thorough mixing eliminates thermal stratification and ensures uniform conditions in tanks, which has been shown to lower overall disinfectant residual demand and reduce the risk of nitrification.
Learn about the hidden risks of ice formation inside water storage tanks, traditional approaches for preventing ice damage and new tools for eliminating ice.
With the arrival of the U.S. Environmental Protection Agency's Stage 2 Disinfectants and Disinfection Byproducts Rule in 2006, water utilities began examining options to achieve compliance. Much of the attention has focused on ways of lowering organic matter concentrations at water treatment plants. Fortunately, distribution system O&M strategies often can be implemented quickly and inexpensively.
Stanly County, in central North Carolina, is typical of many smaller rural water utilities in the U.S. Due to excess capacity in the city water system that supplies the surrounding county, Stanly County receives finished water that is often at or above the Maximum Contaminant Level (MCL) for Total Trihalomethanes (TTHMs). Without a treatment plant of its own, Stanly County is limited to few options for bringing their water into compliance.