Danville continues treating water with activated carbon

DANVILLE — Water plant operators no longer detect an odor in the river at the city’s water intake, but they will continue to use activated carbon until treated water delivered to customers is free of bad taste and odor.

Algae are naturally present in all surface waters and excessive growths into blooms can cause taste and odor problems.

The Virginia Department of Health says carbon is the best solution for removing unpleasant taste and odor caused by such biological activity.

The treatment plant’s filtration system removes both algae and carbon particles before the water enters the distribution system.

“We have been able to remove the bad taste and odor since we began feeding a higher dosage of carbon during the water treatment process,” said Jason Grey, interim director of utilities. “This taste-free and odor-free water will take several days to reach all areas of the city, particularly in those residential areas farthest from the treatment plant.”

Grey told City Council earlier this week that many areas already are reporting their drinking water is back to normal, but the city continues to receive complaints from areas where the taste and odor issue persists.

“We are optimistic that the problem will diminish in all areas as the water pushes through our system,” Grey said Friday.

When the taste and odor issue first emerged in early February, tests conducted on water samples taken from the Dan River confirmed the presence of three species of algae that are associated with taste and odor, including a high concentration of Synura.

In more recent testing, the Virginia Department of Environmental Quality was unable to confirm the presence of algal blooms, but those results were limited to the samples collected on a particular day. The Virginia Department of Health, which oversees drinking water quality, continues to believe algae are the cause of the taste and odor issues.

The Department of Environmental Quality also has been unable to determine the location on the river system where the algal bloom is originating.

“Many citizens have reported to us in recent weeks that they smell a similar odor along the Smith River near Martinsville,” Grey told City Council this week. “We have shared that information – and will continue to share any additional information we receive – with the Virginia Department of Environmental Quality.”

With the recent rainfall, the river flow has increased dramatically, which state officials believe has led to the diminishing odor.

“At this point, we believe our best strategy is to continue feeding an appropriate level of carbon at the water treatment plant in the event the odor in the raw water re-emerges once the river flow returns to lower levels,” Grey said.

The city also has flushed out water storage tanks across the city as recommended by the Virginia Department of Health to remove water with a bad taste and smell.

The water in the system has been through all of the treatment processes, and although the earthy taste and odor of the drinking water are unacceptable to both Danville Utilities and its customers, the Department of Health confirms all tests show Danville’s water meets state and federal regulations.

“We take seriously our responsibility to provide safe, odor- and taste-free water to our customers,” said City Manager Joe King. “We are doing everything we can to resolve this problem and regret the discomfort and inconvenience customers are experiencing.”

 

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