EPA seeks faster cleanup of Superfund site leaching chemicals near Des Moines Water Works

Hazardous waste that is causing a plume of contaminated groundwater, threatening intakes for Des Moines Water Works, the source of drinking water for 600,000 central Iowa residents, is in line for accelerated federal funding and cleanup.

The U.S. Environmental Protection Agency will hold a public meeting in Des Moines on Tuesday to discuss remediation of the contamination, a Superfund site south of downtown Des Moines, by placing it on the National Priorities List later this year. Being on the list would ensure “long-term cleanup efforts, impede further plume migration, and prevent exposure to site contamination,” the EPA said.

The Iowa Department of Natural Resources in 2020 asked the EPA to assume regulatory oversight of the site, known as Lot 46 Valley Gardens TCE, an industrial and commercial area that’s contaminated with trichloroethylene, called TCE. The chemical, a widely used solvent, has been tied to a host of health problems, including heart, liver and kidney damage.

The plume is migrating toward the water works’ Fleur Drive plant infiltration gallery, a network of underground pipes that run about 3 miles along the Raccoon River to collect water. The gallery is “a very good source" of water that seeps through a 30- to 40-foot layer of sand and gravel, helping filter out silt, algae, bacteria and other unwanted materials, said Ted Corrigan, Des Moines Water Works’ CEO.

Being placed on the Superfund National Priorities List would give the EPA “a big hammer to come in here and get things cleaned up,” Corrigan said. “We’re glad they’re here.”

Here’s what to know.

Has TCE been discovered in Des Moines Water Works' water?

Corrigan said no TCE has been discovered in the water works' finished water. Barely detectable levels — 0.8 parts per billion — have been discovered in the gallery system.

Testing showed the system has had 2.7 parts per billion of cis-1,2 dichloroethene, a product created when TCE breaks down, and 1.7 parts per billion in finished water, well below EPA standards.

The maximum contaminant level for TCE in finished water is 5 parts per billion and 70 parts per billion for cis-1,2-dichloroethene, called DCE.

Is water from Des Moines Water Works safe to drink?

Des Moines’ drinking water is safe and meets federal standards, Kellen Ashford, an EPA spokesperson, said in an email Thursday.

“EPA is proposing to take additional steps to ensure the protection of human health and the environment from trichloroethylene and its breakdown products,” like DCE, Ashford said.

“At any point in which conditions change that indicate an increased risk of impact to the drinking water supply, EPA can take action to address immediate threats,” Ashford said.

Does the TCE contamination pose other health threats?

The EPA said TCE and the products of its degradation in soil or groundwater may emit vapors, but that “based on current groundwater data, limited soil gas data, and the distribution of TCE and its degradation products in these samples, EPA has not identified a significant risk of exposure to such vapors at this time.” It said it also has not found concentration levels "of ecological concern at monitoring wells near the Raccoon River."

It added, however, that “investigation of vapor sources and pathways is ongoing.”

Who's responsible for the contamination?

The original source of the contamination hasn't been identified, according to an Iowa DNR official. The agency worked until “progress hit an impasse” in 2019 to create a remediation plan with the property owner, Mid-America Development Group of West Des Moines, the state said in its letter to the EPA.

Mid-America couldn't immediately be reached for comment.

How long has the contamination existed?

The contaminated groundwater plume was discovered in 2004 or 2005. But concerns about the site and its proximity to the Des Moines Water Works infiltration gallery system emerged years earlier, in 1998, when Iowa DNR asked Deluxe Corp., a company previously located there, to install water quality monitoring wells. The EPA said Iowa DNR worked to establish the extent and nature of the groundwater contamination from 2007 to 2019, as well as determine the parties responsible.

What's the next step?

The EPA said in an email it will work to determine “the nature and extent of site contamination, as well as potential cleanup alternatives and costs.” Part of EPA’s process is finding the “potentially responsible parties” that are liable for cleanup.

It said it does not have an estimated timeline for the cleanup. But federal regulators anticipate Lot 46 could be added to the National Priorities List by early 2024.

Where and when is Tuesday's meeting?

At Weeks Middle School, 901 E. Park Ave. in Des Moines. From 6 to 6:45 p.m., representatives from the EPA, Iowa DNR and Des Moines Water Works will be available for one-on-one discussions and questions; from 7 to 7:30 p.m., officials will give a presentation about the site; from 7:30 to 8:30 p.m., officials will answer questions.

Correction: The story has been updated to indicate the correct name of the meeting location: Weeks Middle School.

Donnelle Eller covers agriculture, the environment and energy for the Register. Reach her at deller@registermedia.com or 515-284-8457.

This article originally appeared on Des Moines Register: EPA seeks priority listing for TCE plume threatening Des Moines water