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Water & Energy
Water treatment plant
By KEVIN KILBANE | The Municipal
Raleigh Water in Raleigh, N.C., is throwing a curve at algae and bacteria that can cause taste and odor issues in residents’ drinking water. In early 2019 it launched a pilot project testing use of shade balls in the west reservoir at its E.M. Johnson Water Treatment Plant. The hollow, dark-colored, 4-inch diameter plastic balls float on the surface of a body of water, blocking most sunlight from reaching the water. Sunlight can spur growth of algae and bacteria that give drinking water a bad taste. The plant is one of two water treatment facilities Raleigh Water operates as it provides water and sanitary sewer services to about 610,000 people in the city and several nearby communities. The utility stores raw water from Falls Lake in the plant’s west and east reservoirs before treating it for use as drinking water. Raleigh Water needed about 5 million shade balls to cover the west reservoir surface. “In short, our main water source has had various taste and odor issues over the years due to high algal counts, MIB, geosmin, etc., although in general these issues have been pretty rare, thankfully,” Ed Buchan, Raleigh Water’s senior communications analyst, said in an email. “Thus, we decided to try the shade balls out in one of our terminal reservoirs to see how they worked.” 54 THE MUNICIPAL | AUGUST 2022
MIB, which is 2-Methylisoborneol, and geosmin are natural substances that result from the presence of algae and bacteria in water. Staff members learned about shade balls at an American Water Works Association Annual Conference and Exposition, Buchan said. The utility has limited data on the shade balls’ effectiveness because weather conditions haven’t created algae problems the last few years. However, for the first few weeks the shade balls covered the west reservoir, they reduced MIB and geosmin levels significantly — while the east reservoir showed large increases in both readings, water test data provided by Buchan showed. “Also, our (water plant) manager did say the shade balls have been very effective in dissuading geese and other waterfowl from taking up residence around the reservoir and loitering in the water,” Buchan said. It had been common to have 30 to 50 geese on the west reservoir, but shade balls have nearly eliminated the problem. Shade balls also can be useful in other public utility settings, according to Bryan Stuck, general manager at Environmental Control Company LLC in Wilmington, N.C. The firm makes shade balls
