High benzene contamination found in groundwater 10 feet from Parachute Creek

Levels 400-800 times the state health standard

PARACHUTE, Colo. - Samples taken from new monitoring wells near Parachute Creek show high levels of the toxic chemical benzene just 10 feet from the bank.

Officials have been conducting tests on groundwater near the creek, which is near an oil-like leak from a Williams Midstream natural gas plant. The Colorado Oil and Gas Conservation Commission updated the results Tuesday.

Results from monitoring wells drilled for the latest round of testing showed levels of benzene at 1,900 to 4,100 parts per billion in groundwater about 10 feet from the bank of the creek.

These levels are far above the state health standard for benzene, which is 5 parts per billion, Colorado Department of Natural Resources spokesman Todd Hartman said.

Testing last week showed benzene at a range of 5,800 parts per billion to 18,000 ppb, Hartman said.

The monitoring well with the highest concentration (18,000 ppb) is closest to a recovery trench, which Williams dug to gather and remove leaking hydrocarbons and water.

Samples of surface water in Parachute Creek show no evidence of contamination.

Both the COGCC and consultants for the operators analyzed groundwater elevation data and found that Parachute Creek is a "losing stream" in this area, which means the creek serves to recharge groundwater, instead of groundwater feeding the creek.

This means that the groundwater might not contaminate the creek.

In addition, pumping from the recovery trench is increasing groundwater flow away from Parachute Creek.

Since testing began three weeks ago, operators have removed 4,200 barrels of groundwater and 142 barrels of hydrocarbons.

Operators are bringing additional equipment for faster testing.

Officials from Williams and the state say there's no evidence of contamination in Parachute Creek, which flows into the Colorado River.

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.