Columbus City Utilities officials have shut down two wells south of the city’s wastewater treatment plant after testing revealed positive readings for a man-made chemical.
The wells, south of the treatment plant nearest to the East Fork White River, were taken offline by the city after a second round of testing results obtained this week showed that the 1,4 dioxane chemical was detectable from the wells, according to a report on the city utilities website.
There are now three city wells offline, the two involving 1,4 dioxane and one at the Bartholomew County Fairgrounds that was taken out of service in June after it tested positive for E. coli contamination. That well remains offline for continuing disinfection and monitoring, Reeves said.
Despite the new developments, the Columbus city water is safe to drink and meets all the standards required for drinking water in Indiana, Columbus Mayor Jim Lienhoop and city utilities director Keith Reeves said Tuesday.
Story continues below gallery
However, the city will continue testing for 1,4 dioxane levels at the two wells to determine whether the chemical dissipates over time, Lienhoop said.
Longer term, the city will consider ways to replace the volume of water that comes from those two wells if they cannot be put back in service, the mayor said.
Before next summer, Lienhoop said the city hopes to determine whether it needs to replace the two wells, or possibly develop a new well field.
The chemical could be migrating into the wells from outside the area, the mayor said.
“1,4 dioxane is present in lots of places and is present throughout Indiana,” he said.
Potential costs for any of the options are unknown at this time, he said.
The 1,4 dioxane chemical, used in industrial and commercial applications, commonly shows up as an impurity in household and personal care products, city officials said in the report. It is used as a solvent by many industries, including pharmaceutical and cosmetics production, and also is used to stabilize other solvents inside containers.
City officials are continuing to evaluate how to determine the source of the contamination and what needs to be done to the wells, Reeves said.
Columbus City Utilities has been investigating the matter since late August, after a report published by the Environmental Working Group indicated 1,4 dioxane was in the city’s water. The report said the city’s water had a higher-than-recommended level of the contaminant in its drinking water four years ago.
The test for 1,4 dioxane registered at .482 parts per billion in Columbus’ water system in 2013, which was detected when the city sent its water to be tested through a special federal program, Reeves said. The Environmental Protection Agency’s recommended level for the chemical is a maximum of .35 parts per billion.
The city contends that while the 2013 counts were correct, they were misleading, according to the city’s report on its website.
City officials contend the higher-than-normal result in 2013 was obtained by averaging a non-detectable sample from a Lincoln Park well with a .95 parts per billion and .98 parts per billion test readings detected at the south-side wells near the fairgrounds, instead of using a value of a detection limit at .07 parts per billion.
“The two facilities are considerable distances apart, so the blending of these two sources cannot be assumed for all customers,” utilities officials said in their report.
In subsequent testing this year, the city focused on the fairground wells testing without using the diluted numbers from Lincoln Park, the city report states.
Columbus’ water plant receives raw water from three distinct well zones, Reeves said. Representative wells from each zone were selected to have water samples drawn, as well as samples from the finished water leaving the plant.
The first testing results showed that 1,4 dioxane was at detectable levels in the finished water coming out of the plant, Reeves said. The tests showed .75 parts per billion in finished water in September, and .77 parts per billion in October.
An additional round of tests were ordered to locate the source of the chemical, this time testing all of the remaining wells, and again testing combined raw water and the finished water.
The second round of testing showed positive results for 1,4 dioxane at Wells 14 and 15, located at the westernmost portion of the south well field, Reeves said.
After the wells were taken out of service, tests were performed again on the finished water leaving the treatment facility, which confirmed that 1,4 dioxane levels had dropped below detection limits in the city’s water, according to the report.
The Environmental Protection Agency doesn’t have a specific contaminate level for 1,4 dioxane in drinking water, the city’s report states. The EPA has determined that a .35 parts per billion concentration in drinking water represents a one-in-a-million cancer risk, but sets a lifetime health advisory at 200 parts per billion, many times greater than levels in Columbus, the city report states.
Indiana does not have a state-specific drinking water limit for 1,4 dioxane, the city report states.
Fairgrounds well still offline
In addition to the two wells near the wastewater treatment plant being taking offline, the city’s well at the Bartholomew County fairgrounds also remains out of service after it tested positive for E. coli contamination in June, resulting in a boil-water order for the city.
Reeves said the city continues to work with the Indiana Department of Environmental Management to make sure that disinfection efforts are properly monitored. The well will remain offline until the city is assured another boil order will not be needed, he said.
The city is able to maintain an adequate water supply despite having three wells offline, as water consumption does go down somewhat in the winter months, Reeves said.
Since the early 1950s, Columbus has obtained its drinking water from groundwater — from 22 gravel-packed wells and two filtration plants, one in Lincoln Park near Columbus Regional Hospital and the other just north of Southside Elementary School near the fairgrounds.
Seven wells supply the Lincoln Park plant and are capable of supplying 7,100 gallons of water per minute to the plant, city officials said in their water quality report.
The south-side plant is supplied by 15 wells located near the fairgrounds and southeast of that area, including those on the elementary school property and property east of State Road 11, the report states. This well field can supply 14,800 gallons of water per minute to the southside plant.
Losing the two additional wells brings the total number of wells to 19 generating water for the city.
“But that doesn’t mean we aren’t hurting a bit,” Reeves said of well capacity for the city. “Basically we’re talking about limited water supplies, but we are a long way from that.”
If the city would experience a lengthy drought, as occurred in 2012, there might be some issues of having enough wells to gather the groundwater needed to serve the city he said.
“But it’s not a direct concern now,” he said.
To read the Columbus Utilities report on the 1,4 dioxane contamination, go to columbusutilities.org/ and click on Dioxane Report.