Serving Northern St. Louis County, Minnesota

Tower-Soudan drinking water supply will need secondary treatment system

Jodi Summit
Posted 4/18/19

TOWER-SOUDAN— Results from water testing done by the state shows that the Tower-Breitung public water supply will likely need to add a secondary treatment system in the near future to improve …

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Tower-Soudan drinking water supply will need secondary treatment system

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TOWER-SOUDAN— Results from water testing done by the state shows that the Tower-Breitung public water supply will likely need to add a secondary treatment system in the near future to improve quality and reduce the risk of unhealthy contaminants.

According to wastewater system manager Matt Tuchel, the T-B wastewater board is planning to conduct an engineering study in 2020 to help determine what treatment options will be most effective.

State testing of the water supply was completed in 2015 and 2016 as part of a statewide study, and state officials only recently released the results. For Tower and Breitung, a few of the two dozen samples showed the presence of pathogens, like rotovirus, Cryptosporidium, and Giardia prior to chlorination.

“All this sampling was done prior to the water being treated,” noted Tuchel. The public water system is treated with chlorine, which will treat bacterial (coliform) and viruses, but cannot treat contamination with Giardia and Cryptosporidium.

“There is no concern now about the safety of our water supply,” said Tuchel, “but we will start doing extra monitoring, including regular testing of the water post-treatment.”

“We want to make sure what is safe is really safe,” he said. “We have never had a fecal coliform positive test result on the drinking water supply.”

The testing was conducted as part of the Minnesota Groundwater Virus Monitoring Study.

Over the course of two years, with water tests done every other month (12 total samples), the system’s main well showed contamination with rotovirus in two of the samples and a Cryptosporidium on one sample. The system’s backup well, which is maintained to use in case of problems with the main well, showed one rotovirus and one Giardia detection. Both wells had multiple detections of total coliform.

The public water supply comes from wells that are 60-feet deep, and both are only 50-feet away from the East Two River.

“River water does seep into the well, underground,” Tuchel said.

The testing, which started back in 2015, was before the Tower-Breitung wastewater board had beaver dams removed in the area of the wells. The dams had raised water levels above-ground, creating the potential for well contamination from the beavers. The wastewater board had been forced to use more chlorine and other treatment chemicals, which in turn created an issue with above normal levels of Trihalomethane (THM) and Halocetic Acids (HAA5), which are both by-products of the water treatment process.

Since the beaver dams were removed, the water testing for THM and HAA5 have consistently been within allowable limits.

“This really was testing done in the worst-case scenario,” said Tuchel. “But it is good to have this information. Beavers can become a problem again in the future.”

The study

The Minnesota Department of Health (MDH) conducted this study after the Minnesota Legislature asked MDH to develop and implement a groundwater virus monitoring plan. The study looked for evidence of specific pathogens, including viruses, bacteria, and protozoa, in groundwater supplies. Such pathogens can get into public water supplies when feces from wildlife are able to get into groundwater or directly into a well. If adequate treatment is not provided, people who drink water contaminated with pathogens may become sick. How many people get sick from pathogens in drinking water in the state is unknown, according to MDH.

MDH added bacteria and protozoa to the water monitoring study to get a more complete picture of pathogens in groundwater.

The study included two parts. The first was actual well water monitoring, and the second was a community illness study. During the study period, most wells were sampled every other month for one or two years. About 70-percent of the wells, statewide, that were sampled, had at least one detection of a pathogen. But overall, only 22-percent of the samples had a detection. This suggests that pathogen occurrence is irregular and likely only under certain conditions, the study concluded.

Well water contamination can appear and disappear very quickly, the study said, and the sources of the contamination can change with time. Weather conditions and usage patterns of the well can also impact results.

The community illness portion looked at six communities, half of which treated their water with chlorine and half with untreated water. The study looked to link reported cases of acute gastrointestinal illness to water testing results. The findings of this part of the study were not statistically significant, but did find that during the weeks viruses were detected in the drinking water supply, there were higher rates of reported illness. Higher rates of illness were found among people who had a water filter or softener at home.

If not properly maintained, these devices become less effective and may hold on to contaminants. In addition, the study did not determine how participants were getting sick with gastrointestinal illness, whether it was from the water, a food source, or person-to-person contact.

Tower-Soudan was not a test community for this part of the study

Treatment options

The study shows the need for some type of secondary water treatment, beyond chlorination.

The T-B wastewater board is hoping their upcoming engineering study will provide options. The study, which will cost around $20,000, will also look at methods for removing tannins, which can cause the water to be discolored. This secondary treatment can also pull out surface water contaminants that many enter the well water.

The cost of installing the secondary treatment and the timeline for doing so is unknown at this time, Tuchel said. Low-interest loan money will be available. Tuchel was not certain if grant dollars might be available for such a project.

This is only one of the challenges facing the municipal water and sewer system over the next 10-20 years. New state guidelines for sewage treatment may require a different type of wastewater treatment system, instead of the passive pond treatment system in place currently, Tuchel said.

Home water

treatment

Residents, including those who get their water from private wells, can get more information on home water treatment at the MDH website, www.health.state.mn.us (search for home water treatment for a downloadable pdf).

If you get your drinking water from a public water system, your water system and the Minnesota Department of Health (MDH) regularly test the water for over 100 different contaminants and make sure it meets all Safe Drinking Water Act standards. You can learn more about your water quality by reading your water system’s annual report (called a Consumer Confidence Report [CCR]). The most recent reports are available at Tower City Hall and Breitung Town Hall.

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