The Iowa Department of Natural Resources has required Iowa City officials to install monitoring wells to determine the extent of “legacy” groundwater contaminants dating back decades at Chauncey Swan Park.
Multiple volatile organic chemicals, or VOCs, turned up in underground samples taken from the park, some in concentrations higher than permitted under Iowa law, during environmental assessments done as part of planning for the nearby Chauncey high-rise development, at 100 S. Gilbert St.
The Chauncey development project includes a renovation of the adjacent city-owned park, with green space sloping down toward the ramp where Iowa City holds its farmers markets, with planned outdoor movie screenings and seating areas.
Matt Culp, senior environmental specialist with the Iowa DNR, noted data from the wells also will help officials determine whether any contaminants have migrated off-site from the park.
Based on the DNR’s current information, Culp said, there are no drinking water wells near the site nor are there pathways for human exposure to the chemicals, which he said are approximately 40 feet underground, near where a layer of silty sand meets the bedrock.
Ron Knoche, Iowa City’s public works director, said to his knowledge this marks the first time the city has been required to monitor groundwater at any of its properties. Officials are working with engineering company Terracon, which he said plans to install and sample three groundwater wells in the park.
“At this point in time, we’ll develop a plan, make sure the DNR is comfortable with the location of the wells and then install them,” Knoche said.
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Culp said sampling of the wells will take place quarterly, with Iowa City submitting reports at least annually for up to four years, though potentially fewer, depending on what the data shows.
under the park
State regulators are not positive how contaminants reached Chauncey Swan Park but believe different chemicals could have originated from different sources.
Environmental assessment documents show that, between the 1920s and 1970s, the parcels that now make up the Chauncey property held a gas filling station, two dry cleaners and tin, vulcanizing and auto body repair shops.
Culp said the DNR believes the former dry cleaners likely were the source of the chlorinated solvent cis-1,2-dichloroethylene, or DCE, which he noted was an “industry standard” for those businesses at the time, but that the other uses might have contributed to the pollution, too.
Concentrations of DCE at about 14 times higher than the permissible statewide standard, and vinyl chloride at 119.5 times higher than the standard, were found in groundwater samples collected from a soil boring in the park’s southwest corner in 2017.
Two other chemicals — acetone and toluene — later were found in early 2018, in samples from a supply well installed in the park’s northwest corner as part of a geothermal heating and cooling system planned and later scrapped for the Chauncey building.
Any of the former Chauncey property businesses could have used those chemicals, engineering company Tetra Tech wrote in a January 2019 report it prepared for the U.S. Environmental Protection Agency, which has handled matters stemming from the geothermal system.
Another possible source, the company noted, was a property about one block east of the Chauncey project area, formerly owned by the Iowa City Press-Citizen. That building, constructed in 1920 and now used for apartments, once housed the newspaper’s printing operations, which the report says traditionally involved the use of solvents to clean printing plates.
Two rounds of well samples, collected from the geothermal well in January and March 2018, contained acetone and toluene below applicable state standards.
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Each of the four chemicals can cause damage to the central nervous system when vapors with high concentrations are inhaled.
Tetra Tech noted in its report that a historic geothermal well on the former Press-Citizen property “could become a conduit for contamination of groundwater” on account of its age, and that “proper plugging and abandonment of this well may be prudent to ensure future protection of groundwater.”
In an emailed statement Thursday, an EPA representative said there currently are no immediate plans to plug or abandon that well.
“EPA plans to conduct an additional CERCLA” — Comprehensive Environmental Response, Compensation, and Liability Act, better known as the Superfund — “site assessment in the coming year to further characterize the extent and nature of the contamination,” she said.
Public Works Director Knoche said the monitoring wells are planned to be installed at Chauncey Swan Park after renovation work is complete there, projecting they likely would be “in the ground” this fall.
The DNR’s Culp said, “We want to get the groundwater monitoring in but we certainly don’t want to hamper the city’s ability to make that a great space.”
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