BY LISA STAYTON
MOUNTAIN CITIZEN
INEZ — Martin County Water Board Chairman Tim Thoma says recent widespread brown water in the county is a symptom of corrosive water dislodging mineral buildup inside aging pipes.
“This is the root cause,” Thoma told the board in a July 22 meeting, citing the county’s negative Langelier Saturation Index (LSI) values, which indicate the water is corrosive. At warmer summer temperatures, the corrosiveness increases, causing scale buildup inside water lines to break loose and dissolve into the water flowing to residents’ homes.
Recent water testing backs up the claim. While water leaving the treatment plant contained just 0.03 milligrams per liter of manganese, testing in the distribution system showed levels 10 times higher — hitting 0.3 mg/L, the U.S. EPA’s lifetime health advisory threshold. Iron levels were also elevated in the distribution system.
“Manganese is looking for a dancing partner,” Thoma said. “The dancing partner in this case is sulfate. Manganese, when combined with sulfate, will form a dark scale inside the pipe. And when you take warm water that’s got a Langelier scale of -1.5 to -1.2 and put it in that pipe, it will bring that out of solution. Hence, why you’ve got a higher manganese level in the distribution system than in the plant.”
To fix the issue, Thoma said the district must alter its water treatment process. This change could require adding chemicals, reconfiguring plant operations, and working with engineers to develop a formal plan. He estimated the process could take three to eight months.
“In the interim, our only avenue is to run a slightly higher pH out of the plant and continue to flush the system,” Thoma said.
He noted that state Division of Water inspectors who visited the treatment plant during the recent brown water event confirmed that other counties with similar LSI values are also dealing with discoloration.
Alliance Water Resources regional operations manager Todd Adams said the local DOW inspector cited four other systems outside Martin County experiencing the same issue.
Board member Nina McCoy asked what those communities were doing to address the issue.
“You’re not going to like the answer,” Adams replied. “It’s a recurring problem that happens on every system; it happens about twice a year. They flush the lines out and it reoccurs the following year without any operational changes. We had the same issue last year around this same time.”
McCoy said she was unaware of any issues last summer.
“It just wasn’t as bad,” Adams said.
Thoma made clear that stopgap solutions are not enough.
“Brown water coming out of the faucet is a problem. And there is a solution — and we’re going to implement it,” Thoma concluded. “We’re going to solve the problem.”
The Langelier Saturation Index (LSI) is a calculated number used to assess the corrosiveness or scaling potential of water. It measures the balance between pH, alkalinity, calcium hardness, total dissolved solids and temperature to determine whether water will deposit minerals (scale) or dissolve them (corrosion). A negative LSI indicates corrosive water that can eat away at pipes and release metals or minerals into the water. A positive LSI suggests scaling, which can clog pipes with mineral buildup.