An investigation into low levels of an industrial solvent found in two now-closed city wells is entering its next phase as investigators try to determine how the chemical contaminated the aquifer supplying Columbus’ drinking water.
Officials from Intera, a geoscience and engineering solutions company with offices in Bloomington, completed a report on the status of the city’s south wellfield, where wells 14 and 15 were shut down last October after 1,4 dioxane was detected.
Columbus City Utilities has allocated $350,000, or about 2.3 percent of its $15 million annual budget, to study the cause of the 1,4 dioxane contamination, said Keith Reeves during his final Columbus Utility Board meeting as utilities director before retiring. Intera has spent about $200,000 so far on the investigation.
Columbus is one of several Indiana cities that tested above the .35 parts per billion Environmental Protection Agency recommended limit for the solvent, testing at .48 parts per billion in the city water system in 2013.
City officials and investigators emphasized there is no federal standard for 1,4 dioxane limits. Other Indiana cities testing above the EPA recommendations in 2013 were LaPorte and Evansville.
Through a variety of testing options, Intera officials had new information for Columbus Utility Board members Thursday about where the 1,4 dioxane is in the aquifer supplying Columbus’ water.
Rhett Moore, Intera’s principal hydrologist, explained his company’s investigative process into contamination at the two wells, which are located east of State Road 11 and south of Garden City, near the East Fork White River.
But the company cannot yet say where the chemical originated or how far north or south it may have spread, only that it has been detected at the bottom of the aquifer between the wells and the river. That means the company has determined the contamination appears to be to the east of the wells rather than the west, Moore said.
That finding deepens the mystery as to how the chemical got there and whether other wells close to wells 14 and 15, and near the river, namely wells 16 and 17, could be in danger of contamination in the future because of where the chemical has been found.
Moore explained the company began its investigation by sampling the well water in the two now-closed wells, and also sampled along the river banks, where they found higher 1,4 dioxane levels compared to the wells. No 1,4 dioxane was detected in the river itself, he said.
To test water in the aquifer, the company installed a network of monitoring test wells and did soil borings looking for the location of the chemical and how far it had spread. It placed shallow Piezometer monitors in the river and repaired two multi-level monitoring wells already in the well field to obtain results.
The company also did what Moore described as an exhaustive search of Indiana Department of Environmental Management records and historic aerial photos of different entities that had been located in the area near the wells and the river.
Moore said there were many legacy sites identified by IDEM on the west side of the river, but all had been evaluated by the agency and had been determined not to be a threat to the well field, leaving that part of the investigation inconclusive.
The city’s old landfill is upriver from the wellfield. While Moore said there is no indication that the contamination could have come from that site as the chemical isn’t detectable there, it also can’t be ruled out.
Sonic core testing of the subsurface around the wells did not find any source of the contamination, he said.
Tests for 1,4 dioxane were repeated in April, with the levels found to be lower in wells 14 and 15 than in January.
However, the company concluded that the results indicated the contamination was higher near the river and originated east of wells 14 and 15, believed to be at the bottom of the aquifer near those wells, Moore said. The chemical is slightly denser than water, causing it to go to the bottom of the aquifer, he said.
He explained that there is interaction between the aquifer and the river, with some water intermingling between the two depending on conditions and well pumping.
In the next phase of the investigation, Moore said the company will continue to evaluate the risk to the water supply and evaluate some short-term options for replacing pumping capacity lost from the inactivation of the two wells. The company will also provide long-term options for more capacity, including recommendations for a new location for a well field.
Moore said it is possible the chemical could be found at new locations the city might consider for a well field.
In the next phase, the company plans to look into how the aquifer is interacting with the river and refine the water flow model to try to determine why the chemical is in that location.
Environmental Working Group, a Washington D.C.-based nonprofit working on environmental issues, said that more than a million pounds of 1,4 dioxane was produced in the U.S. or imported to the country in 2015, and 675,000 pounds of the substance has been released into the environment nationwide.
The group said the chemical is a common impurity in cosmetics and household cleaning products, and is found in shampoos, foaming soaps, bubble baths, lotions and laundry soap.
Because the chemical is man-made, it can be detected in groundwater, and has been in a large number of Indiana cities, including a large cluster around Indianapolis that did not test above the EPA guidelines but did test positive for the chemical, the nonprofit said.
Columbus’ drinking water is from groundwater obtained using 22 gravel-packed wells and two filtration plans, according to Columbus City Utilities.
The city has 15 to 20 wells in the southern well field, but only the two have been shut down at this time because of 1,4 dioxane. City officials have said that typical household water filters probably do not have the capacity to remove even the small amounts of 1,4 dioxane.
Environmental Working Group said water at .35 parts per billion with 1,4 dioxane would cause one cancer case in a lifetime. At .48 parts per billion, a slightly higher risk was predicted, the nonprofit said.
Exposure to the chemical can lead to cancer, liver or kidney damage, lung irritation and eye and skin irritation, according to the nonprofit.
Moore described the continuing investigation as somewhat of a moving target as the company is trying to determine where the chemical is, if it’s moving and if it has moved, how far. Since there is some interaction between the river and the aquifer, investigators must also determine how that groundwater is moving and where.
The chemical is not a regulated contaminant for drinking water under federal or Indiana drinking water regulations, Reeves said in an earlier interview.
The city’s most recent water testing report showed the city’s water complied with all current standards in place for drinking water. The city utilities serves about 35,575 people in Columbus and 8,445 people for the Southwestern Bartholomew Water Co., which obtains its drinking water from Columbus.
[sc:pullout-title pullout-title=”About 1,4 dioxane” ][sc:pullout-text-begin]
The chemical 1,4 dioxane is used in industrial and commercial applications, and does show up as an impurity in household and personal care products.
It is used as a solvent by many industries, including pharmaceutical and cosmetics production, and also is used to stabilize other solvents inside containers.
The Environmental Protection Agency has set a recommended limit of .35 parts per billion for the chemical in drinking water.
The chemical is not a regulated contaminant for drinking water under federal or Indiana drinking water regulations, according to Columbus City Utilities.
[sc:pullout-text-end][sc:pullout-title pullout-title=”Coming Monday” ][sc:pullout-text-begin]
Meet Scott Dompke, new Columbus City Utilities Director.
[sc:pullout-text-end]
