A mystery pipe along the banks of the South Platte River in Commerce City is leaking toxic levels of arsenic and other heavy metals into the riverbank and waterway, but no one knows where the pipe originates, how long it has been pouring the dangerous chemicals into the river and who is responsible for it.
City officials have not developed a plan to stop the discharge as they investigate the source of water polluting one of the Front Range’s most important rivers. Arsenic can be toxic to people, animals and aquatic life.
It’s not a huge problem because it’s not a major flow of water into the river, said John Spear, an environmental engineering professor at the .
“But it’s enough of a problem where it’s worth fixing, and it could take a while to fix and figure out who’s going to pay for it,” said Spear, who reviewed a consultant’s analysis of what the city is calling an “illicit discharge” for The Denver Post. “In the meantime, the riparian corridor could suffer because there’s arsenic coming into it.”
Commerce City officials are reluctant to talk about the pipe, citing their ongoing investigation.
“…While we have not yet identified the source of the discharge and total volumes, we have been able to confirm the presence of arsenic, iron and other heavy metals in the discharge,” Travis Huntington, a city spokesman, wrote in an emailed statement. “Commerce City is following all applicable state and federal requirements and will keep relevant stakeholders updated as we identify the source and advance remediation efforts.”
The pipe was discovered in February after a resident reported it through the city’s online portal that allows people to flag potholes, streetlights that are out, and other infrastructure issues, Huntington said. But it is unclear how long the pipe has been spilling hazardous chemicals into the South Platte. No one has determined how much water from the pipe is flowing into the river.
Commerce City officials hired a consulting firm to test the water on March 9.
The consultant’s report, which The Post obtained from the Hazardous Materials and Waste Management Division, shows that arsenic levels in the mud along the riverbank are hundreds of times higher than amounts naturally found in Colorado soil.
The tests, conducted by of Fort Collins, found 528 milligrams of arsenic per kilogram of soil in the mud just below the pipe. At the water’s edge, the contaminant level was 73 milligrams of arsenic per kilogram of soil, according to the CGRS report.
Arsenic concentrations in Colorado soil typically range from 1 to 20 milligrams per kilogram of soil.
“The concentrations detected at the site substantially exceed these background levels and are not consistent with naturally occurring conditions alone, suggesting a potential localized source associated with the discharge,” the consultant’s report stated.
That means the water is most likely coming from an old mine or industrial site.
The arsenic in the water spilling directly from the pipe had “marginally high” levels, testing at 11.15 and 11.35 micrograms per liter. That level is higher than what is acceptable for public drinking water levels, the report said. In some cases, that level of arsenic can be naturally occurring in groundwater.
Still, the consultants recommended further evaluation to determine the source of the spill.
‘Like a kitchen sponge’
Spear, the School of Mines professor, said the higher concentrations in the soil mean the arsenic has been accumulating for years as water pours from the pipe onto the ground.
“The soil is removing the arsenic from the water and holding onto the arsenic,” he said. “It’s like a kitchen sponge.”
But the sponge can’t hold all the water, so some arsenic is flowing into the river.
Water coming from the pipe also contains elevated levels of manganese that are more than 100 times the amount recommended for tap water, according to the CGRS report.
Readings taken from water at the pipe were 5,408.51 and 5,226.68micrograms per liter. Manganese is typically less than 50 micrograms per liter in water.
Manganese naturally occurs in ground and surface water, but the high levels found in the pipe indicate it is runoff from an industrial site. The mineral is a nutrient important to human health, but it can be toxic if people are exposed to large amounts or over an extended period.
“Such elevated levels are not representative of typical background conditions and may reflect a potential localized source associated with the discharge,” the consultant’s report said. “Given the magnitude of exceedance, additional evaluation is warranted to assess the source and extent of manganese in the discharge.”
The consultant’s testing also found low levels of 1,2-Dibromo-3-chloropropane, a man-made chemical used as a fungicide. The fungicide, also known as DBCP, became notorious decades ago when male workers on Latin American banana plantations became sterile after the chemical was absorbed into their skin.
The presence of DBCP led Spear to conclude that the source of the discharge is from an old industrial site.
“The fact that it’s present means you can use it as a tracer for human activity,” Spear said. “Somebody did something at that site and we can see it today. It’s probably not groundwater coming up from the subsurface. It’s probably coming through historic use and what somebody did in the past.”
The pipe flows under property owned by a real estate investor, according to Adams County records, and is used by a tree surgeon. But there is no indication that either of those entities is responsible for the pipe or the substances discharging from it.
Downstream water districts warned
Branden Ingersoll, a spokesman for the state health department’s Hazardous Materials Division, said the data show arsenic concentration in the water is acceptable for surface water but not for tap water.
As a precaution, Commerce City has notified downstream water districts, including Brighton, Thornton and the South Adams County Water and Sanitation District, of the illicit discharge. No one has reported impacts on fish or aquatic life, he said.
“We are recommending that Commerce City conduct additional evaluation of the pipe and the site of the release to assess the potential source, impact on soils and remediation of soils,” Ingersoll said.
The earth between the pipe and the riverbank is covered in a slick-looking, bright orange goop. The soil turned orange because microorganisms are breaking down the iron and other heavy metals in the water, Spear said.
“That’s actually normal,” he said. “It can look really toxic and really gross, but it’s a good thing to see that.”
The South Platte is a source of drinking water for thousands of Front Range residents, and the river also provides water for livestock and crops in northern Colorado and western Nebraska.
The first step to solving the problem is to determine the source of the water discharge, Spear said. Commerce City and the state health department need to figure out a remedy, most likely by treating the water to eliminate the toxic levels of arsenic and manganese.
Those government agencies will also need to figure out who pays for it, and if they connect the discharge to an industrial source, they could seek compensation from that business — if it still exists, he said.
“Commerce City is doing their own due diligence and I respect them for that,” Spear said. “They’re going to need to get to the bottom of this.”
