DENVER - Hydrocarbon contamination that was found in groundwater near Parachute Creek in western Colorado was from a leak due to a failed pressure gauge on a pipeline, according to the energy company that discovered the contamination.
"The leak was stopped on January 3, 2013, at 12:33 a.m. The gauge was part of a valve set on a 4-inch natural gas liquids pipeline that belongs to Williams Partners," the Williams company said in a written statement.
State officials said Wednesday they're still investigating.
Hydrocarbons, including the carcinogen benzene, were discovered in soil and groundwater near the Williams natural gas processing plant in Parachute in early March.
Williams said Wednesday that a pressure gauge failed in December, and a leak started Dec. 20. It was stopped Jan. 3. At that time, crews were unaware just how much had seeped out.
The contamination was rediscovered in March when workers excavated the area. Monitoring wells drilled in various locations around the creek revealed benzene levels as high as 5,800 parts per billion to 18,000 ppb.
These levels are far above the state health standard for benzene, which is 5 ppb, Colorado Department of Natural Resources spokesman Todd Hartman said.
Williams now estimates more than 10,000 gallons of natural gas liquids leaked from the pressure gauge.
About 6,000 gallons have been recovered.
Williams says the contamination hasn't reached Parachute Creek.