Benzene levels at a point in Parachute Creek near the Williams Co. gas plant spill doubled in a week to 3.9 parts per billion Monday, just short of the 5 ppb considered safe for drinking water.

The Colorado Department of Public Health and Environment said new sparging systems at the sample point and upstream are being installed to stop contaminated groundwater from reaching the creek north of Parachute. The new systems will be turned on the week of July 22.

Benzene contamination has not been detected at any other test points, including where the town of Parachute diverts creek water, typically for irrigation, a health department news release said.

Crews have been working to clean up a spill that was revealed in March. The spill, blamed on a mechanical failure, released more than 10,000 gallons of hydrocarbon liquids from a valve, contaminating soil and groundwater. Williams, its subsidiary Bargath and state and federal agencies scrambled to protect the creek, which flows into the Colorado River.

— The Denver Post