A research team from Virginia Tech said on Friday that it was unable to identify what might have caused the unusual taste and odor events during 2015 in drinking water for Danville and South Boston.
However, the team found no evidence of a long-term impact on the Dan River from the coal ash spill that occurred upstream from Danville in February 2014.
The team from Virginia Tech’s Civil and Environmental Engineering Department recently concluded its study of the Dan River and the Smith River. The study began in May 2016, and as part of the study, the team conducted monthly sampling at 12 sites along the two rivers from August 2016 to September 2017.
“During the course of this year, there was never a taste and odor event that occurred, so we were not able to identify the cause of the taste and odor events (in 2015),” said Dr. Dan Gallagher, a professor in the Civil and Environmental Engineering Department.
However, the data collected from the sampling will be valuable if future taste and odor events occur.
“We (now) have a great background set of data so that if something does come up, then somebody can access that data and determine what is different from normal conditions,” Gallagher said.
Danville and South Boston use the Dan River as a source for potable water. The two municipalities experienced taste and odor issues in the raw and treated drinking water in February through June of 2015, and again in October through December of 2015.
Throughout the taste and odor episodes, the water in the City of Danville’s system went through all of the treatment processes, and the Office of Drinking Water confirmed all tests showed Danville’s drinking water met state and federal regulations.
To mitigate the unusual taste and odor, water plant operators fed a higher dosage of activated carbon in the treatment process.
In addition, Danville Utilities is developing plans to convert the former Dan River Inc. reservoir at Schoolfield into a raw water impoundment. The plans are contingent on the project being included in the budget for the next fiscal year.
The impoundment would hold 20 million gallons of water, which would provide enough water for four days. Currently, the City can store up to 12 million gallons – enough for three days of use – of treated water.
Following the 2015 taste and odor events, Virginia Tech received a grant from the National Fish and Wildlife Foundation to collect extensive data of water quality in the Dan River and the Smith River, which is a tributary of the Dan River.
From historical records dating back to 1954, these events were the first recorded severe episode of an algae, fungi or bacteria-related taste and odor problem in the Dan River for Danville or South Boston.
Gallagher presented the findings at a public information meeting held Friday afternoon at the Institute for Advance Learning and Research. An executive summary of the links can be found at http://www.danvilleva.gov/RiverStudy.