Parachute Creek tests show ‘non-detect’ results
Post Independent Staff
PARACHUTE — A week’s worth of tests of Parachute Creek north of here, where a leaky pressure gauge spilled thousands of gallons of natural-gas liquids into the ground, have shown no signs of continuing contamination from the leak, a spokesman for the state health department wrote in an email to the Post Independent on Friday.
“I heard from our folks this morning that it has been six consecutive days that all surface water sampling locations have come back as non-detect,” wrote Mark Salley, public information official for the Colorado Department of Public Health and Environment (CDPHE).
In addition, Salley wrote, “Monitoring continues, surface water [of the creek] and groundwater, and shows at this time the plume is stable.”
Attempts to contact Salley for further comments were not successful. In his email, he wrote that further updates about the plume may only be forthcoming “if there were some significant change at the site, but not anticipating that.”
Donna Gray, with the community relations office for Williams Midstream, the company playing the key role in the cleanup of the plume and its effects, said that “not much has changed. We continue to do the air sparging, and that seems to be working very well.”
Sparging essentially is injecting the water of Parachute Creek, and in the groundwater monitoring wells, with forced air, which bubbles to the surface and disperses benzene, a carcinogenic chemical compound commonly associated with oil and gas activities.
Benzene was detected at dangerously high levels in the center of the plume, nearest to the source of the leak, where concentrations ranged from 5,800 parts per billion (ppb) to 18,000 ppb, according to samples taken from ground water monitoring wells located about 30 feet from the creek.
A later test, from a groundwater monitoring site just 10 feet from the creek, came back positive for benzene at concentrations between 1,900 ppb and 4,100 ppb.
The maximum allowable standard for benzene in Parachute Creek, which is classified by the State of Colorado as a non-drinking-water source, is 5,300 ppb, a standard meant to protect aquatic life forms from being poisoned.
The highest level of benzene so far detected in the creek has been just over 5 ppb, which happens to be the maximum concentration allowed in drinking water sources by state and federal regulators.
But benzene levels in the creek have been dropping steadily since the source of the leak was found and plugged, according to Williams and the CDPHE.
Gray said the company has a better idea of the size of the plume of contaminated soil surrounding the leak site, but she did not have the details available to her on Friday.
She said the company’s crews had excavated much of the soil surrounding the leak site and believes it has gotten most of the contamination out of the ground, though she did not have the exact details of that work available to her on Friday.
Williams and another company, Bargath LLC, continue to try to determine whether the plume has stabilized or is still expanding and moving downstream, toward Parachute, Gray said.
The leak is now believed to have first gotten started in December 2012, according to Williams. Company workers detected the leak in January 2013, worked to plug it up, and believed it was too small to warrant reporting to the Colorado Oil and Gas Conservation Commission (COGCC), according to statements by Williams officials.
But evidence that the leak had started up again was detected in early March, and reported on March 8 to the COGCC. By March 29, Williams had estimated the leak spilled more than 10,000 gallons of hydrocarbons from the soil.
While the spill initially was under the jurisdiction of the COGCC, in late April the CDPHE took over the operation and used an advisory stating that Williams faced possible state sanctions for improperly disposing of hazardous wastes.
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