Contaminated water has been flowing into Sand Creek and the South Platte River from the Suncor Energy oil refinery north of Denver, and company officials on Wednesday said they were monitoring conditions and “will make any necessary repairs” to a containment area that has been failing.
A sheen of benzene and other chemicals first surfaced on Sand Creek on May 7, prompting work to bolster the containment area, company officials said in a bulletin posted Wednesday on the company’s Facebook page.
Sunday’s heavy rains raised the level of the creek, breaching the containment area. However, “rapidly changing conditions made it unsafe to continue the work,” Suncor officials wrote.
“Since discovering the sheen, we have taken a number of steps to ensure containment, identify the material and understand the potential source,” company officials wrote. “We continue to take this situation seriously and are working with the appropriate regulatory agencies as we continue to investigate.”
Suncor officials said they’ve drawn water samples from Sand Creek and the South Platte River and tested these for benzene, toluene, ethylbenzene, xylene and methyl tertiary butyl ether. The results showed concentrations did not exceed state standards for surface water in those waterways, company officials said.
Colorado Department of Public Health and Environment officials did not respond immediately to queries about conditions at the refinery.
The refinery is located at the north edge of Denver in Commerce City, just up Sand Creek from the confluence where the creek flows into the South Platte River.
“Who is watching this?” Adams County Commissioner Steve O’Dorisio said. “I’m concerned about the problems that continue to occur.”
The water pollution problems at the refinery follow recent air emissions that have raised concerns from state health officials and residents. In March, state officials announced Suncor will pay up to $9 million in a settlement for multiple air-pollution violations at the refinery since 2017.
Suncor officials said air monitoring near the refinery along the Sand Creek Greenway bike path shows that contamination levels remain below the levels that the U.S. Occupational Safety and Health Administration permits.
For years, Suncor has been facing groundwater contamination problems at the refinery that have led to seepage of benzene and other toxic chemicals into water and soil. Full cleanup has been slow.
State health inspectors identified a broken “dead leg” pipe beneath a storage tank as a source of previous spills. Suncor capped it in 2011, but liquids that leaked from the pipe into an underground toxic plume still fouled the surface water in Sand Creek, which flows into the South Platte.
Benzene-contaminated groundwater also has spread in other directions — along the concrete-lined Burlington irrigation ditch and under the adjacent Metro Wastewater Plant and under the bed of Sand Creek.
State health officials have said they do not believe the plume has reached the river directly and that the size of the plume was stable or shrinking. But benzene levels in the past have been elevated, according to state data.
State officials repeatedly have ordered Suncor to make repairs at the refinery including work around storage tanks. Company contractors have constructed underground clay walls and have removed hundreds of thousands of gallons of liquid hydrocarbons from trenches.
Suncor officials said they’ve looked for other broken pipes.
Colorado public health officials have ordered the installation of more walls and monitoring wells to track toxic plumes, as well as aeration systems that suck benzene vapors from soil. More than 100 aeration wells have been placed between the refinery and Metro Wastewater.
But extracting benzene from soil has been difficult because this can spread fumes into the air. State air officials have ordered emission controls, including charcoal filters, to minimize air pollution.
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