Decades after chemical dumping, a toxic chemical plume in Colorado still worries some Arapahoe County residents

A pollution controversy spanning decades in Colorado history continues to leave some Arapahoe County residents frustrated and demanding more action from state and federal agencies.

The crux of the issue stems from an underground plume of toxic chemicals from the Lowry Landfill that's near hundreds of homes. The landfill is just east of the intersection of E-470 and Hampden avenue in Arapahoe County.

EPA studies show the underground chemical plume grew as far as three miles north of the landfill following hazardous chemical dumping at the site in the 1970s. The plume also grew underneath the Murphy Creek Golf Course.

Arapahoe County resident Bonnie Rader has lived in the area since the start of the pollution controversy. 

She remembers how chemical dumping at the site back then created irritating air pollution that caused her and her family to have acute sicknesses. 

"Kids would come in with headaches when they were outside playing, and my youngest son would go into asthma attacks and bronchial pneumonia with no fever," Rader recalls. "Once they covered the pits, we didn't have those problems anymore."

The "pits" she's referring to are areas underground where the chemicals were historically dumped. Rader says they are capped off above ground, but underground, she worries they could pose a risk of breaching and contaminating nearby water supplies.  

"We're worried about what's going to happen underneath," Rader said.

Because of that hazardous waste, the EPA designated the Lowry Landfill as a Superfund site, and millions of dollars were spent to clean it up. 

Despite those efforts, the underground plume of chemical waste escaped the site, and flowed further north, directly adjacent to homes in the Murphy Creek neighborhood of Aurora.

Regardless, the EPA insists "the contamination at the Lowry Landfill Superfund Site is contained; and the location of the contamination is highly monitored." 

"All components of the remedy are complete and have been in place for several decades and are regularly monitored," a spokesperson for the EPA wrote to CBS News Colorado. "An extensive monitoring network, found in the Groundwater Monitoring Plan, is in place to continuously monitor the effectiveness of the components. The monitoring plan, complete with multiple contingency plans, ensures that any compromised remedial component will be quickly identified and addressed." 

The EPA says the plume has been shrinking thanks to groundwater treatment operations, pointing to this timelapse of the change in the plume size from 2005 to 2020. 

However, testing documents from 2021 and 2023 show the shrinking in those two years was minimal. EPA maps of the plume from 2021 and 2023 show the size of the plume is nearly the same, and a CBS News Colorado analysis of EPA documents shows a harmful chemical from the plume called "1,4-dioxane" was found in 2023 at levels still considered too high by EPA standards along Murphy Creek next to subdivisions and townhomes.

The EPA maintains the plume is not directly underneath the homes.

As the community nearby continues to grow in population, and new homes continue to be built close to the plume, Rader thinks levels should be tested further north, west, and east, to make sure plume hasn't grown.

"We're really concerned about on further down this development over here is Gun Club Estates and they're all on acreage and they're all well water," Rader said pointing to a neighborhood near the plume as she drove CBS News Colorado Investigator Kati Weis on a tour around the community. "We know there's dioxane down in these wells here and there, the wells are just right across the road from them."

Arapahoe County officials say they are making sure "appropriate zoning rules are in place for sites in the County's jurisdiction surrounding the Landfill."

"Per the institutional controls, properties are not to be used for daycares, schools, hospitals or single or multi-family residential uses," a spokesperson for Arapahoe County, Jordan Ames, tells CBS News Colorado. 

The EPA says private drinking wells nearby are regularly tested and no contamination has been found in the last 17 years.

"Really, we're thankful for that," Rader said. "We don't want them to find it."

The EPA has studied potential health risks if in case private drinking water wells are compromised by 1,4-dioxane in the future, and found the hypothetical cancer risk would be 6 in a million.

According to a 2020 risk assessment, "if a future hypothetical resident utilized the shallow aquifer for drinking water at an assumed concentration of 2.9 µg/L... 6 people out of a total population of 1,000,000 exposed in this scenario might be expected to develop cancer related to 1,4-dioxane exposure from the shallow groundwater."

Read the full health risk assessment by clicking here. 

But Rader also has concerns about the chemical affecting nearby households through sump pumps in the homes. 

"We are concerned it might be pulling in some of the water, and they might be vaporizing up into their homes, chemicals getting up into their homes," Rader explained. 

But the EPA says there's no reason for concern there, siting the 2020 health risk assessment, which said potential contamination to sump pumps "would not result in significant exposure to residents."

"The 1,4-dioxane plume north of the landfill is present in shallow groundwater that generally follows Murphy Creek and is currently present beneath a golf course and not residential homes," a spokesperson for the EPA tells CBS News Colorado. 

"Forever chemicals" are an emerging focus at the landfill in 2024

While 1,4-dioxane has been the focus of testing, Rader also worries about potential PFAS pollution.

PFAS are called "forever" chemicals, because they don't readily break down in the environment. They can cause a host of health problems, and they are commonly found at landfills.

As CBS News Colorado has reported, PFAS has been the focus of many new EPA regulations to protect human health in recent years.

Right now, PFAS testing isn't required at Superfund sites. However, that's expected to change in a couple of months, when the EPA updates its regulations pertaining to PFAS monitoring at Superfund sites. 

"We do anticipate PFAS sampling at Lowry Landfill during the next five-year review, after the PFOA and PFOS rulemaking becomes effective," a spokesperson for the Colorado Department of Public Health and Environment tells CBS News Colorado. 

Until then, the EPA says even if PFAS were present at the Lowry Landfill, they wouldn't pose a risk, because there aren't "exposure pathways."

But Rader feels if 1,4-dioxane traveled underground, so could PFAS. 

She admits there has been productive progress to mitigate the underground chemicals, thanks to  a new water treatment facility that the EPA says treats 8.7 million gallons of contaminated groundwater a month.

"The water treatment plant uses a natural biological process and advanced oxidation treatment to treat for organic compounds and molybdenum. The pretreated water is then discharged to a Metro Water for further treatment," an EPA spokesperson said. "The Lowry Landfill Water Treatment Plant won the Metro Water's Gold Star Award three times."

The EPA added that the plant also uses a carbon filter process, which can help filter out PFAS contamination. 

Waste Management, the company that operates the landfill, added that PFAS was recently conducted near the site.

"EPA does not have evidence of PFAS contamination at the Lowry Landfill site," said WM spokesperson Jennifer Wargo. "The Colorado Department of Public Health and the Environment recently tested for both PFAS and 1,4-dioxane in private wells north and east of the site and none were impacted."

A proposed recycling facility near the Superfund site adds to citizen group apprehension

However, Rader feels more should be done to protect her neighbors.

A few years ago, Rader was appointed the chair of a citizens advisory group, or CAG, for Lowry Landfill cleanup efforts, but funding for the group wasn't renewed, and she feels her pleas to government agencies for more serious actions have been ignored.

"It's tiring because they just keep refusing to do the right thing," Rader said. "I would say they're doing harm to our environment and possibly to people, and it's a wrong way for our government to be acting."

Her CAG wrote a letter to the Inspector General's office a couple of weeks ago expressing "deep concerns" with handling of the site, and asking for an independent investigation. 

Specifically, her CAG is concerned about the proposed construction of a new recycling facility at the landfill, which is operated by Waste Management. She worries construction could disturb the underground chemical waste pits, causing them to breach and cause destructive pollution of nearby rivers and municipal drinking water supplies. 

She believes a seismic impact study should be done before the proposal is given a green light. 

"After 40 years of the public witnessing WM construction failures, illegal decision-making and the consequential negative impacts to our environment, we are extremely concerned that the government agencies charged with protecting the public and the environment will make the mistake of trusting WM again," Rader said in her January 2023 letter to the IG. 

But the EPA says the facility would not be located exactly in the area that's designated a Superfund site, just nearby. 

"The property for the Recycling Center purchased by Waste Management is outside of the Lowry Landfill Superfund Site boundary and within the buffer zone of properties owned by the Lowry Environmental Protection Trust," an EPA spokesperson said. "Acceptable uses for this property are outlined in the 2005 Lowry Landfill Institutional Control Plan and associated environmental covenant. Use as a Recycling Center Complex is consistent with the Institutional Control Plan and land uses allowed under the environmental covenant."

WM echoed those statements, writing to CBS News Colorado, "WM's recycling facility will be located on non-Lowry Landfill property and is a typical construction project which will have no impacts on the Lowry Landfill."

Officials with Arapahoe County also provided the following statement about the proposed site:

"The private land identified as the site of proposed Waste Management recycling facility was rezoned for heavy industrial usage in February 2023 following hearings before the Arapahoe County Planning Commission and the Board of County Commissioners. This is a usage consistent with the institutional control regulations. 

"Waste Management submitted a site plan to Arapahoe County Public Works and Development in November 2022. The review process includes an examination of the plans for adherence to setback, layout, water, sewage, drainage, and stormwater management regulations. Arapahoe County submitted Waste Management's initial site plan to the CDPHE, the Colorado Geologic Survey, and the EPA for comment. No concerns were raised.

"The most recent site plan was submitted to Arapahoe County in November 2023 and the county is currently waiting for a final submittal from Waste Management."

While the facility is located in unincorporated Arapahoe County, the city of Aurora has been following the issue for years, because of how the plume traveled into city limits. 

Ryan Luby, deputy director of communications for the city said, "we remain up to speed on any developments related to the site with the interests of Aurora residents and property owners at heart."

He added that the city's drinking water supplies come from the mountains and would not be impacted by any breaches.

"The city's drinking water comes from surface water sources in the mountains and is stored in facilities with watershed protection measures in place," Luby said. "Our water supply is continuously monitored to ensure quality, and it exceeds federal standards."

Finally, the city and county of Denver also has a role in this decades-long controversy, because from the mid-1960s until 1980, the City and County of Denver operated the Lowry Landfill.

"At the time the landfill was in operation, little was known about the health and environmental impacts of industrial waste disposal," said Ryann Money with Denver's health department. "Denver and Waste Management are now partnered to manage the site's cleanup together."

Wargo with WM added, "In its most recently published assessment in 2022, the EPA once again determined that the remedy at the site to contain waste is protective of human health and the environment – and that nobody is being exposed to contaminants at the site."

WM says the EPA also requires twice annual "Site Status Reports" to demonstrate remedy plans are still working. 

To read the most recently available 2023 status report, containing the most recent testing records, click here.