Benzene in monitoring wells at site of plume near Parachute |

Benzene in monitoring wells at site of plume near Parachute

John Colson
Glenwood Springs Post Independent
Aspen CO Colorado

PARACHUTE, Colo. – Officials late on Thursday reported detecting the toxic hydrocarbon chemical benzene in water samples from monitoring wells near Parachute Creek at levels thousands of times higher than state safety standards for exposure to the chemical.

According to the Colorado Oil and Gas Conservation Commission, the test results are from three monitoring wells between Parachute Creek and a “recovery trench” dug by Williams Midstream, owner of a nearby gas-processing plant and the lead company working to contain a suspected, but as yet undetected, leak.

The creek itself, however, has not been contaminated, according to reports from Williams and from the commission.

Water samples taken from the creek by both entities showed no signs of hydrocarbon contamination, as of reports issued Thursday.

The monitoring-well test results, as reported by Williams, showed benzene at a range of 5,800 to 18,000 parts per billion in the wells, according to a statement released Thursday at 6 p.m. by the commission.

The maximum level of benzene safe for human exposure, according to the statement, is 5 parts per billion.

Benzene is a known carcinogen, linked most commonly to leukemia and other types of blood cancer, according to the website

Benzene also is known as a volatile organic compound often associated with oil- and gas-drilling activities.

The monitoring wells were between the creek and a recovery trench, which Williams dug to gather and remove leaking hydrocarbons and water from the plume. The wells were roughly 30 feet from the creek, according to the Colorado Oil and Gas Conservation Commission.

On Thursday evening, Williams reportedly was drilling new monitoring wells at a distance of 10 feet from the creek to provide a clearer image of the plume’s impact on the groundwater.

The commission and its consultants, according to its statement, believe Parachute Creek to be a “losing stream” in hydrological terms, meaning the creek recharges the groundwater in the area rather than vice versa, so water flows away from the creek.

The statement also maintained that the act of pumping liquid hydrocarbons and water out of the recovery trench “is enhancing groundwater flow away from Parachute Creek.”

Officials in the nearest town to the plume, Parachute, have said they are not anticipating any negative effects from the plume on the town’s drinking water because the intake is on the Colorado River upstream from the confluence of the river and the creek.

The plume of hydrocarbon-drenched soil was found March 8, and Williams has reported the extraction of 143 barrels (or more than 6,000 gallons) of unspecified hydrocarbon compounds and at least 3,600 barrels (or more than 153,600 gallons) of contaminated water.

The plume was discovered by Williams crews preparing the ground for an expansion of a nearby natural-gas processing plant, working in a 40-foot right of way that crosses land owned by WPX Energy, a natural-gas-drilling company.

Both firms are offshoots of Williams Production RMT, which split in two last year.

The size of the plume, estimated to be 200 feet long, 70 feet wide and perhaps 14 feet deep, has not changed since it was first discovered, according to Williams.

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