The City of Rockville, Maryland has taken a proactive approach to meet water quality regulatory compliance for their drinking water system. However, an unexpected notice of violation for exceeding the Maximum Contaminant Level (MCL) of Total Trihalomethanes (TTHMs) in 2008 caused the City to critically examine water quality in their water distribution system.
The Town of Atwater, Minnesota has seen its share of cold winter weather, but the January 2014 "polar vortex" storm set new records. Atwater has had a history of problems with ice formation inside their single 100,000 gallon elevated storage tank and researched various options for reducing the risk of ice. .
Central Highlands Water, west of Melbourne, had difficulties maintaining disinfectant residual in their system. With years of drought, and substantial decreases in water use as a result of changed customer behavior, maintaining residual at the end of the system became difficult.
Rural water systems across the United States face a range of challenges in maintaining water quality in their distribution systems. Unlike large municipal systems, rural water systems often have a distribution network that is spread out over many miles. This can result in high water age and low disinfectant residual in parts of their system.
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.