Contaminated area from hydrocarbons continues to spread
Groundwater monitoring wells have found contamination as far as 800 feet from the presumed center of a hydrocarbons leak near Parachute Creek, and also across the creek from the leak site, as the area of known contamination keeps growing.
In addition, what are called diesel-range organics (DROs) were detected in an absorbent boom that had been in place in the creek itself, in the first sign of potential contamination of creekwater related to the leak. And state Department of Natural Resources spokesman Todd Hartman said a creek water sample on March 9 in the investigation area also showed the presence of DROs.
However, spokesman Matthew Allen of the Environmental Protection Agency said the levels of that substance in the boom after accumulating over 10 days was very low, and it is believed to have come from other sources upstream.
The DROs also were found in an upstream sample March 9, and Hartman said subsequent tests at those two sites and other surface water sampling locations since then have shown no more hits for the substance.
Kirby Wynn, oil and gas liaison for Garfield County, said the developments are of great concern to the county.
“It’s certainly an alarming shift in the situation,” he said.
The developments were made public exactly a month after Williams first reported contaminated soil just east of the creek March 8 in a pipeline corridor that goes beneath the waterway. Three pipelines in the corridor serve Williams’ adjacent gas processing plant.
Some 6,000 gallons of hydrocarbons have been removed from the leak site, and the leak source hasn’t been determined. The investigation has centered on the area around an above-ground valve set for a 4-inch natural gas liquids line that leaves the plant, and around a nearby interceptor trench.
High levels of benzene in groundwater previously had been reported as far as 325 feet from the primary investigation site, and as close as 10 feet from the creek. But no groundwater contamination previously had been found on the other side of the creek from the leak site.
State investigators and Williams previously have said the creek appears to be a “losing creek,” meaning groundwater beneath it appears to flow away from it toward the central leak site, helping protect it from the contamination. With contamination now across the creek, Hartman said he doesn’t know what that means, but added, “We believe it’s a losing stream all around at this stage,” meaning the flow on the other side of the creek also is away from it.
“I have no indication right now that would indicate we feel differently about that,” he said.
Hartman said a thin layer of liquid hydrocarbons was found in a monitoring well 800 feet east of the primary investigation area and in the first monitoring well installed on the creek’s south side, across the creek from the leak area.
“Laboratory analysis of the groundwater from these wells was not available as of (Monday) afternoon,” he said in a press release. “Additional monitoring wells are being installed along the southern bank of the creek to the northwest. Tests are ongoing to determine whether the liquid hydrocarbons are similar to those recovered near the primary interceptor trench and above-ground valve set.”
Hartman said Williams has undertaken additional measures on the north side of the creek to protect it, including digging a series of trenches to lower the groundwater level and remove liquid hydrocarbons and contaminated water near the stream’s edge.
Authorities previously have said there has been no evidence of impact to the creek from the leak. Hartman said he was referring to benzene contamination. Benzene is a carcinogen and byproduct of oil and gas development.
Hartman said WPX Energy, the landowner in the area, replaced its absorbent booms in the creek and did lab analysis on the spongy boom material previously in place for 10 days. It showed diesel-range organics at 213 to 349 parts per million, and no detections of benzene or gasoline-range organics.
“The source of DRO is unknown,” he said.
Williams has placed two additional booms. One is downstream of any groundwater monitoring wells where hydrocarbons have been detected. Another is upstream of the investigation area, and was placed to determine if any DROs are entering the area from upstream.
Allen said anything can transport DROs into a creek, such as someone walking into the creek with contamination on their boots.
Allen said chemical compounds making up diesel can be found in nature, but DROs wouldn’t be expected to show up naturally in a creek.
If pollutants are found to be impacting the creek, the EPA has authority under federal law to take additional measures to address the situation, he said. But he said it sounds as if the levels detected were low enough that the EPA investigator involved determined it didn’t require new action by the agency.
“It wasn’t anything that sparked concern,” he said.
Wynn said more information needs to be gathered about the DROs, but they “may be of great concern.”
The Colorado Oil and Gas Conservation Commission, part of the Department of Natural Resources, has led the investigation. But the EPA and Colorado Department of Public Health and Environment also have been involved.
Said Hartman, “We are in a great deal of communication with both CDPHE and EPA about this site and their involvement could increase.”
Allen said if the EPA’s involvement escalates, that doesn’t necessarily mean it would take over the investigation. Often in such instances a “joint unified command” involving the EPA, state agencies and responsible parties all work together to respond to a problem, he said.
On Thursday, Williams revealed that a pressure gauge on the valve set was discovered Jan. 3 to have been leaking. But the company says the gauge probably leaked fewer than 25 gallons, and wouldn’t explain benzene having traveled hundreds of feet in groundwater by now.
But Bob Arrington, a member of the Garfield County Energy Advisory Board and a retired mechanical engineer with pipeline experience, says he thinks such a gauge could leak 6,000 gallons in just 4 1/2 hours.
“I know if you lose a pressure gauge it can gush out on you,” he said.
He also said groundwater moves fast enough to explain the benzene’s travel.
Williams spokesman Tom Droege said Monday he can’t speculate about the contribution caused by the Jan. 3 leak. “We’re definitely looking at it, though,” he said.