PARACHUTE, Colo. - Samples taken from monitoring wells near an oil-like leak close to a Williams Midstream natural gas plant show high benzene levels near Parachute Creek.
Monitoring wells showed benzene at a range of 5,800 parts per billion to 18,000 ppb, Colorado Department of Natural Resources spokesman Todd Hartman said Thursday..
The monitoring well with the highest concentration (18,000 ppb) is nearest to the recovery trench and current area of source investigation. These levels are significantly above the state health standard for benzene of 5 ppb, Hartman said. Operators are currently drilling another set of monitoring wells about 10 feet from Parachute Creek to further delineate groundwater impacts, the Colorado Dept. of Natural Resources said.
Numerous samples of surface waters in Parachute Creek, including samples taken by the Colorado Oil and Gas Conservation Commission, have shown no evidence of contamination. Both the COGCC and consultants for the operators have analyzed groundwater elevation data and find that Parachute Creek is a “losing stream” in this area, which means the creek serves to recharge groundwater, as opposed to groundwater feeding the creek. Hydrological consultants for the operators concluded this to be the case from data gathered March 22 and March 27.
In addition, pumping from the recovery trench is enhancing groundwater flow away from Parachute Creek. Since the onset of this event two weeks ago, operators have removed 4,200 barrels of groundwater and 142 barrels of hydrocarbons.
Williams and state officials say there's no evidence of contamination in Parachute Creek, which flows into the Colorado River.
More monitoring wells will be drilled about 10 feet from the creek to get more details on groundwater impacts.
Company workers looking for the source of the leak are focusing on a valve box for a pipeline carrying natural gas liquids away from the natural gas plant.