PARACHUTE CREEK - Benzene, a cancer-causing toxin, has been found in a newly completed groundwater monitoring well just 10 feet from Parachute Creek, where investigators have been looking for nearly four weeks into a suspected leak in natural-gas pipelines, tanks or other facilities in the area.
According to an update from Todd Hartman, spokesman for the Colorado Oil and Gas Conservation Commission, sampling results from the new well showed benzene in the water at levels between 1,900 parts per billion and 4,100 parts per billion.
The maximum safe level of benzene for human exposure is 5 parts per billion, according to the U.S. Center for Disease
Control. Benzene, a liquid hydrocarbon long associated with natural gas drilling activities, is a known carcinogen linked to leukemia and birth defects.
The new monitoring well is about 325 feet to the southeast of a set of valves and a "recovery trench" dug by Williams Midstream, the energy company conducting the cleanup, according to Hartman's statement.
Williams, which owns a natural-gas processing plant near the plume site, dug the new monitoring well and others after benzene was found in an earlier set of monitoring wells, which were closer to the plume and 30 feet from Parachute Creek. Benzene was reported from those wells at a range of 5,800 parts per billion and 18,000 part per billion.
Williams, and state officials with the state commission, have been at the scene since the plume was discovered on March 8, while Williams was conducting soil analysis in preparation for expansion of the processing plant.
The site is roughly four miles up Parachute Creek from the town of Parachute, which is more than 40 miles west of Glenwood Springs in Garfield County. The creek flows into the Colorado River near Parachute.
According to Hartman, "Repeated sampling over 18 days has shown no evidence of benzene contaminating Parachute Creek. COGCC continues to believe the hydraulic gradient makes it difficult for groundwater to move into the stream as current water level data indicates the creek serves to recharge groundwater as opposed to groundwater feeding the creek."
State officials now believe the plume of hydrocarbons found along Parachute Creek may be older than first believed.
According to an April 1 statement by Hartman, "The situation suggests to COGCC investigators the possibility there may have been historic releases in the vicinity of the valve set and the recovery trench that occurred over a period of time."
Hartman wrote that the company still had not located an "active source" for what is believed to be a leak or leaks in the pipelines, tanks or the natural-gas processing plant.
Both Williams and WPX Energy, a drilling company, were cited by the Colorado Oil and Gas Conservation Commission with responsibility for cleaning up the plume.
The plume was found in a 40-foot right of way held by Williams across land owned by WPX Energy.
The two companies are spinoffs from Williams Production RMT, an energy company that split apart in 2012, creating the two new firms.