Even though drinking water well number four in Hill City has had its arsenic level in an acceptable range for a month, testing will continue on the well, said Brett McMacken, city administrator for Hill City.
The most recent test was done on March 5 and it came back at nine parts per million for arsenic in the water, which is one below the 10 parts per million threshold.
“We are compliant now,” McMacken said. “We don’t need to send out compliance letters. But we still will be testing quarterly, and we will be doing arsenic testing to look for trends and indicators. We need to see what needs to be fixed and worked on beyond the well itself.”
The well was built before the Environmental Protection Agency (EPA) threshold for arsenic in water was at 50 parts per billion.
McMacken said at a Hill City Common Council meeting March 25 that a test of the arsenic level in the well was conducted in 2001, and that came back at 14 parts per million.
At that time, the well was compliant.
The EPA threshold changed in 2006 to the level it is at now — 10 parts per million.
By McMacken’s thinking, the arsenic in the water is naturally occurring and being caused by shifting soil.
McMacken said the city is looking at a water filtration device that would fix the problem. However, the device would be costly, McMacken said, and could cost between $150,000 and $200,000.
The filter within the device needs to be replaced about every two years, McMacken said, and that, too, he said, would be costly.
Another issue with the filter is that someone would need to be constantly monitoring it, he said, which would lead to more cost in order to hire someone or pay someone to do just that.
The filter itself, when removed, would be considered to be hazardous waste, he said, because arsenic is considered to be a hazardous material.
This would create problems with removing the filter, McMacken said, along with additional costs.
With the latest round of testing, McMacken said they “didn’t do anything special” to help the well pass.
There has been no new equipment installed, he added.
However, due to the fact that different samples taken at different times have yielded different results, McMacken said he feels the need to continue to test the well.
Public safety is still the main concern, he said.