A valve box is one possible source of an oil-like leak close to a Williams Midstream natural gas plant that shows high benzene levels near Parachute Creek, CO, officials said Thursday. But there’s still no evidence of contamination in the creek, which flows into the Colorado River.
Samples from monitoring wells showed benzene levels of 5,800 to 18,000 parts per billion, which is far above the state health standard of 5 parts per billion, Colorado Department of Natural Resources spokesman Todd Hartman said Thursday. The monitoring well with the highest benzene concentration was in an area under investigation as the source of the leak.
It was the first indication since Williams officials discovered the plume March 8 of benzene levels in the groundwater. Officials will drill more monitoring wells about 10 feet from Parachute Creek to get more details on groundwater impacts. So far, the data suggest Parachute Creek recharges groundwater, as opposed to groundwater recharging the creek.
Company workers who are trying to determine the source of the leak are focusing on a valve box for a pipeline carrying natural gas liquids away from the natural gas plant.
Matt Lepore, director of the Colorado Oil and Gas Conservation Commission, which regulates the industry, said Wednesday they do not know the size of the leak. “We have not truly begun to determine the full footprint of the plume,” he said.
Williams Midstream spokeswoman Donna Gray said Wednesday the tests show there is no evidence that Parachute Creek itself suffered any contamination by the leak.
Retired engineer Bob Arrington, an industry critic, has questioned Lepore’s contention that it appears any contamination would flow away from the creek due to differences in elevation.
Work crews are continuing to excavate and inspect 120 feet of 30-inch pipeline, along with other equipment, in search of the source of the oil-like leak about four miles up Parachute Creek. Officials feel the leak soaked the ground with more than 6,000 gallons of oil-like fluid and more than 153,600 gallons of contaminated water.
The site has a crisscross of underground pipelines and tanks that belong to Williams and WPX Energy, which is a natural gas drilling company. Both firms are subsidiaries of Williams Production RMT.
Since discovering the plume, Williams has been vacuuming liquid hydrocarbons and water from the site and using water-quality monitoring wells to determine the size of the plume and effects on groundwater.