Williams: Valve gauge caused hydrocarbons leak
Williams said Wednesday that a failed pressure gauge on a valve for its natural gas liquids pipeline is the source of hydrocarbons contamination near its Parachute Gas Plant, and it estimates that more than 4,000 gallons of leaked fluids have yet to be recovered.
The announcement comes six days after the company first publicly revealed the problem with the gauge. But it had said last week that the gauge was thought to have leaked far too little fluid to account for most of the 6,000 gallons of hydrocarbons recovered to date.
In a news release Wednesday, Williams said a preliminary analysis of meter data now indicates the gauge leaked from Dec. 20 until the leak was discovered and the gauge removed on Jan. 3.
“By the time the leak was stopped … the company estimates up to 241 barrels of natural gas liquids entered the soil at the valve location,” it said.
A barrel is 42 gallons. About 100 barrels, or 4,200 gallons, remain unrecovered from the site.
Williams estimates that 80 percent of what leaked vaporized before entering the soil.
High benzene levels have been found in groundwater monitoring wells in the contamination area. Williams Wednesday reported a detection of dissolved benzene nearly 1,000 feet from the valve site — the farthest such detection reported so far.
“The assessment is ongoing into whether the benzene is related to the natural gas liquids released from the broken pressure gauge… .” the company said.
“Williams has opened a broader examination of the property in an effort to further determine the area of impact, collect samples for testing and capture additional hydrocarbon fluids from the soil.”
Natural gas liquids include substances such as ethane, butane and propane. The gas plant removes these marketable liquids from raw natural gas.
Todd Hartman, spokesman for the state Department of Natural Resources, said Wednesday, “The area of an above-ground valve set has long been the focus of the source investigation, and the scenario outlined by Williams provides a possible explanation of a release in this area. However, the investigation of the cause or causes of the impacts to soil and groundwater will continue until we can determine whether the release described by Williams accounts for the situation on the ground.”
Williams discovered contaminated soil March 8 as it did pipeline location work in preparation for the construction of a new gas processing unit at the plant.
Last week, a Williams official mentioned the pressure gauge leak during a presentation before the Garfield County Energy Advisory Board. But he said the amount thought to have leaked was less than 25 gallons — not enough to even require a report to the state.
EAB representative Bob Arrington, a retired mechanical engineer living in Battlement Mesa, had challenged that idea, saying the amount of liquids recovered to date could leak from a gauge in a matter of hours.
“It was a very likely suspect,” he said Wednesday.
Williams says water samples analyzed by independent laboratories indicate Parachute Creek hasn’t been affected by the hydrocarbons discovered in the soil. Tests have shown the occasional presence of what are called diesel-range organics in the water, but also have shown the concurrent presence of those organics upstream, which authorities have indicated suggest the organics may be coming from a source such as contaminated runoff from roads.
This week, for the first time, investigators reported benzene in groundwater on the opposite side of Parachute Creek from the valve area. Initially, authorities said benzene on that south side of the waterway was just adjacent to the creek, and three wells 50 feet south of the creek revealed no benzene. But Hartman said Wednesday that was based on preliminary field information, and benzene concentrations in those three wells since have been determined to range from 51 to 450 parts per billion. The safe drinking water standard for benzene is 5 ppb or less.
Surface water samples taken Wednesday about 2.5 miles downstream, where the town of Parachute diverts water for irrigation, show no evidence of impact, he said.
A bill now being considered in the legislature would require reporting within 24 hours of all spills of oil and exploration and production waste involving one barrel or more. Current Colorado Oil and Gas Conservation Commission rules require reporting of general spills of five barrels or more within 10 days, and immediate reporting of spills of any size if they affect or threaten a surface water supply.
Arrington called the bill a good idea.
“There are certain chemicals that you spill just a small amount, it’s terribly deadly, and they’re dealing with hundreds of chemicals and the rule would apply to all of them,” he said.
A tighter reporting requirement also would help ensure that companies get serious about their handling of substances, he said.
“You have to have a heightened sense that it’s very important to do so,” he said.