MDT continues to monitor wells in Plains

A public meeting was held Tuesday evening for Plains residents whose groundwater has been affected by the Montana Department of Transportation (MDT) salt contamination. The meeting was organized by Kimberly Joner, a property owner whose water has been affected by the salt.

The area impacted starts from the location of the MDT shop in Plains northwest of town. It then follows a northwest path between Lower Lynch Creek Road and Highway 200 to Lyla Lane.

The meeting was led by Laura Alvey from the Montana Department of Environmental Quality (DEQ). Alvey stated that the salt in the groundwater was discovered in July of 2012, when a sample of the well water at the MDT site showed salt impacts at their location. MDT had samples taken from neighboring wells later that year. MDT reported the contamination to the DEQ in November of 2012 and a month later, MDT was issued a Notice of Violation by the DEQ, along with a layout and plan on how to come back into compliance, said Alvey. She also explained to the public what “salt” actually means to the DEQ and not to confuse it with magnesium chloride.

MDT does not use mag chloride in the Plains area or surrounding areas, Alvey said, nor do they store it at any of their facilities. However, they do use and store sodium chloride, better known as salt. The salt is used by MDT by mixing it with sand and gravel, which is then put on the roads as a de-icer. The downfall with the salt, Alvey said, is when it is stored out in the open and comes in contact with water such as rain or snow. It then dissolves and releases the sodium and chloride ions separately. Those ions can then be absorbed by the ground. Over time, this can result in higher levels of salt in the groundwater. It wasn’t until the 80s and 90s that MDT started using higher concentrations of salt for highway de-icing solutions. Current statewide practice is a solid salt mix of 10 percent by volume into sand for winter maintenance, Alvey stated.

“The DEQ and MDT will continue working together to improve the groundwater in the affected area for as long as it takes,” Alvey said. MDT moved their previous open-area salt storage in Plains to a new covered area in 2017. Currently MDT provides bottled water to 10 homes and three office buildings. In 2018, three homes which had Class III water samples received “Whole Home Water” solutions. That consisted of drilling deep wells in order to reach the lower aquifer not contaminated by the salt. Along with the new deep wells came a new challenge named arsenic, Alvey said. The amounts of arsenic were too high if left untreated, Alvey stated, and the only way to make the water safe for residents was to install water softeners. So far, MDT has paid an estimated cost of $16,000-$18,000 per each deep well and $3,000 for each water softener system, said Brian Goodman with MDT.

“It is unfortunate the salt has contaminated the groundwater,” Goodman said. “We are working with residents on an individual basis to find a solution that will best work for them.” MDT has plans to drill three more deep wells in 2019 for those that are in the Class III category. MDT will continue to sample the surrounding wells four times a year and address any issues that arise on a case-by-case basis. According to both Goodman and Alvey, there is no time frame on how long it will take for the salt levels to dissolve.

For more information regarding the issue, contact Alvey at (406) 444-0212 or Goodman at (406) 444-7632. Information is also available at http://deq.mt.gov/land/statesuperfund/mdtplains.