Parachute Creek tests benzene-free for 2 days
Tests showed no benzene in Parachute Creek Tuesday and Wednesday, in another sign that remediation efforts related to a natural gas liquids leak there are proving effective.
Aeration treatment of the creek and groundwater “has done a good job,” Parachute town administrator Robert Knight said Thursday.
Williams estimates that about 10,000 gallons of natural gas liquids leaked this winter into soil and groundwater from a pipeline leaving its gas processing plant up the creek valley. It has been using air sparging and related methods to remove carcinogenic benzene in groundwater and the creek at a point 1,300 feet downstream where the benzene has been moving from the groundwater into the surface water.
Benzene in surface water once barely topped the state drinking water standard of 5 parts per billion (although the standard doesn’t apply to the creek), and for a time showed up at lower levels at a few points downstream. However, Williams noted in a recent update at its http://www.answersforparachute.com website that those benzene levels have steadily declined since May 2, although trace levels at the one measurement site had continued to linger.
“Surface water samples from Parachute Creek indicate that Williams continues to make progress in its remediation efforts to remove benzene from a defined area of Parachute Creek, as well as from groundwater,” the company said in that update.
No benzene has ever been detected where Parachute diverts water for its town irrigation system farther downstream. Knight said diversions into that system began about two weeks ago. He said that with the success in efforts to clean up the creek, he’s not hearing any concerns from residents about the irrigation water.
Of greater concern to him is the low level of the creek due to the lack of snowpack, he said. The leak situation has raised questions about how benzene conditions might change when spring runoff occurs, but Knight said he flew over the creek watershed and the snowpack that feeds it already was gone. “We’re down to August levels. We haven’t even seen the creek rise,” he said.
As of last Friday, Williams had estimated that it had recovered about 6,766 gallons of the leaked natural gas liquids.
It is projecting that a water treatment system it will use to remove and clean groundwater before returning it to the aquifer will be in service by June.