Benzene near Parachute leak is monitored, still within limits

Weekend tests continue to show the presence of benzene in Parachute Creek downstream of a natural gas liquids leak, but at what the state Department of Natural Resources said are trace amounts.

In fact, while the detections were somewhat below the standard of 5 parts per billion for drinking water, they are far under what’s allowable for the creek, agency spokesman Todd Hartman said in a press release.

“Since Parachute Creek has not been designated as a drinking water supply by the state Water Quality Control Commission, the actual benzene standard on the creek is 5,300 ppb to protect aquatic life,” he said.

The creek does supply the irrigation system for the town of Parachute and its residents. However, there continue to be no benzene detections at the diversion point for that system, 2.7 miles downstream from where the leak is believed to have occurred.

Thousands of gallons of hydrocarbons leaked in a pipeline corridor near Williams’ gas processing plant up the creek valley. Williams says the source was a faulty pressure gauge on a natural gas liquids pipeline leaving the plant.

High benzene levels have been found in groundwater since early in an investigation that started in March, but the first detection of benzene in the creek wasn’t until last Thursday.

On Saturday, benzene was detected 1,800 feet downstream from the pipeline corridor at 3.1 parts per billion, a level slightly higher than previous readings. That detection site is where groundwater is believed to be introducing benzene into the creek. No benzene was found at that location Sunday, and 3 ppb was detected Monday.

Saturday and Sunday readings at monitoring points 2,500 and 3,700 feet from the pipeline area ranged from 1.5 to 1.1 ppb, with no results available for Monday.

Work continues on installation of an interceptor trench to strip benzene from groundwater above the creek contamination point, and to remove benzene at two locations in the creek.

“Operators have drilled several additional monitoring wells to determine the extent of impacted groundwater. These new monitoring wells are not detecting benzene, an indication that delineation of the affected groundwater continues to improve,” Hartman said.

Also over the weekend, Bob Arrington, a retired engineer in Battlement Mesa and member of Garfield County’s Energy Advisory Board, wrote Gov. John Hickenlooper, urging him to have the Colorado Department of Public Health and Environment rather than Colorado Oil and Gas Conservation Commission lead the leak investigation.

Arrington wrote that Williams has struggled with its own leak response, initially even doubting that the burst pressure gauge could leak that much fluid, and he argued that the commission doesn’t have the staff or training to oversee remediation.

“The proper agency is CDPHE,” he wrote.


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