‘Gift from nature’ eases threat of contaminants in creek
When a Williams pipeline leaked contaminants that reached Parachute Creek in the spring of 2013, the company had “a gift from nature” to thank for the fact that the harm to the creek wasn’t far worse.
That’s according to David Walker, a state regulator who has played a lead role in overseeing the leak cleanup.
Two years later, Williams can thank its own actions, taken under the watchful eyes of state and federal regulators, for getting the spill site cleaned up to the point that the threat of further contamination to the creek has been deemed to have been abated.
As a result, the Environmental Protection Agency in September lifted an enforcement order requiring Williams to take measures to protect the creek. In a letter to Williams, the agency said the company had complied with the order and that the agency had “determined that the threat of oil release to Parachute Creek … has been mitigated.”
That’s a “very important” finding, said Walker, an environmental health specialist with the Hazardous Materials and Waste Management Division of the Colorado Department of Public Health and Environment.
He said the EPA’s action last fall is also highly unusual.
“EPA almost never closes out (enforcement orders) before complete remediation is done, so it shows EPA is trusting Williams and the state to complete the job.”
“We’ve made some remarkable progress,” Pat McCown, Williams’ senior manager of operations for western Colorado’s Piceance Basin, said in a presentation to Garfield County’s Energy Advisory Board last week.
But he also added that the EPA’s action meant “really nothing” to Williams as far as its remediation work, just signifying that the EPA was comfortable with having the state take the lead role in overseeing that work.
“From our standpoint, and really the progression of the cleanup, there wasn’t any change,” he said.
The leak involved natural gas liquids that escaped from a burst pressure gauge on the valve set of a 4-inch-diameter pipeline leading from a nearby Williams gas processing plant. The plant extracts butane, propane and other liquids from gas, and the pipeline carrying them crosses beneath the creek northwest of Parachute to reach tanks and another pipeline on the other side.
The leak was discovered in March 2013, but Williams later realized it had occurred the prior December and into early January, leaking an estimated 50,000 gallons. The company estimated that most of that vaporized, but about 10,000 gallons leaked into the ground.
Benzene, a carcinogen, briefly was detected in the creek, barely exceeding the state drinking water standard of 5 parts per billion, although that standard doesn’t apply to the creek. None has been detected in the creek since August 2013.
The creek is a tributary to the Colorado River, but no benzene made it that far downstream.
High groundwater benzene levels have persisted, although cleanup efforts have reduced their concentrations, and Walker said the overall contamination plume is about half its original size.
Still, groundwater contamination in the area of the leak source includes benzene levels topping 10,000 parts per billion.
The state’s maximum allowable benzene level in the creek is 5,300 ppb, to protect aquatic life. But the state wants the cleanup to get groundwater levels down to 5 ppb, something Walker believes will take another year or more to accomplish.
But an area about 1,000 feet downgradient from the leak site where groundwater containing dissolved benzene reached the creek has been cleaned up, ending that contamination threat to the creek, Walker said.
WHAT WORRIED THE EPA
Meanwhile, at the leak source area, Williams has cleaned up the liquid-phase layer of hydrocarbons on top of the groundwater table, Walker said.
That layer of gasoline-like hydrocarbons had been as much as a foot thick, and the EPA had worried it would rise up and go into the creek, he said.
“That’s the stuff, if it gets into the creek, it travels very quickly and creates a sheen on the creek, which everybody does not want,” he said.
Walker said that “for Williams, it’s an absolutely amazing thing that that never happened.”
Had it happened, the liquids would have spread on the creek surface, creating a “situation where you have to go out and clean rocks, and clean ducks and (other) animals because it coats them,” Walker said.
By contrast, the dissolved benzene was fairly easily removed from the creek with the help of an aeration system, because benzene prefers to vaporize in air rather than remain in water, he said.
Walker said there are few other places where liquid-phase hydrocarbons wouldn’t have made it into a creek in similar circumstances.
But thanks to that aforementioned “gift from nature,” the bottom of Parachute Creek is at least 2 feet above the top of the groundwater table where the leak occurred.
“Most places, groundwater is in connection with the creek,” he said.
While the liquid hydrocarbons layer didn’t spread in the groundwater more than a few hundred feet, groundwater containing dissolved benzene spread further and was able to reach the creek where the creek and groundwater intersect farther downstream.
The cleanup effort
Williams’ cleanup has involved efforts including “air sparging” in which air is injected into groundwater to remove benzene, and a soil vapor extraction system in which benzene and natural gas liquids are extracted by air from a borehole by creating a vacuum.
Two of the systems have been shut down after no more contamination has been detected up- or down-gradient from them, although groundwater monitoring in those areas continues, McCown said.
Two of the systems continue to operate, including what Walker called a “very large, very high-volume soil vapor extraction system” in the source area of the leak.
“Williams has been very aggressive in doing the treatment of the groundwater,” Walker said. “They put in multiple groundwater remediation systems to make sure this gets cleaned up quickly.
“… They have done everything we have asked of them and in fact most of the time they’re ahead” of what the state is asking, he said.
Said McCown, “We’re going to continue to do what it takes to get it cleaned up. We realize we’ve still got some work to do and we’re committed to doing that work and to getting this site cleaned up.”
Pipeline operating again
Walker said Williams put the pipeline back into operation nearly a year ago with approval of his agency and the EPA.
“They did a lot of things to make sure another release like this would not happen,” he said.
These included moving valves several hundred feet away from surface water and adjusting Williams’ pipeline-monitoring program and alarm systems so they can detect smaller changes in pressure.
Walker said the leak that occurred was low-pressure and wasn’t detected by the equipment in place at the time.
McCown said Williams has had some prevention-oriented discussions with others in the industry regarding pipeline leak monitoring as a result of the Parachute incident.
While Williams needed the state and EPA approvals to put the pipeline back in service because a leak had occurred, no federal agency oversees that style of pipeline in general, even at a creek crossing, Walker said.
“Our agency gets involved when a leak occurs,” he said.
But absent a leak, the Williams pipeline also isn’t subject to state regulation.
Williams has said the federal Occupational Safety and Health Administration does have a regulatory role over the pipeline. That’s apparently because it’s part of the operation of the nearby plant.