Resident near creek questions benzene levels
A state official says regulators are seeking to protect Parachute Creek according to drinking water standards even though they technically don’t apply.
The comment by David Walker, with the Hazardous Materials and Waste Management Division of the Colorado Department of Public Health and Environment, came after a resident living near the creek downstream of a natural gas liquids leak questioned the standard applying to the creek.
A leak from a pressure gauge on a pipeline leaving Williams’ gas processing plant has resulting in carcinogenic benzene contaminating groundwater and the creek. While some groundwater benzene levels are high, measurements in the creek only once have exceeded the state drinking water standard of 5 parts per billion, reaching 5.3 ppb Wednesday.
While CDPHE regulators have accused Williams of breaking state rules with the groundwater contamination, it technically hasn’t violated any surface water standard because water isn’t pulled directly from the creek for drinking, Walker said. Instead, the state’s Water Quality Control Division’s maximum allowable benzene level in the creek is 5,300 ppb, to protect aquatic life.
Howard Orona has a domestic well about 20 feet from the creek and said it’s probably only 25 feet deep. A citizen representative on the Garfield County Energy Advisory Board, he expressed concern at the board’s meeting Thursday that benzene in surface water could migrate into his shallow well water.
“For that creek to be pushing into the groundwater in my case, I would think that would be considered drinking water,” he said.
Walker said that despite the 5,300-ppb standard on the creek, “we are trying to protect to drinking water standards because it’s the correct thing to do.”
Williams tested Orona’s water a few weeks ago and it was benzene-free. On Friday, the company agreed to test it again and continue doing so on a regular basis, something Walker said he would have required had the company not volunteered to do it.
He said he agrees it’s possible for contaminated creek water to reach a nearby domestic well, and testing Orona’s well is the right thing to do.
At the same time, he noted that Orona’s well is more than a mile from where benzene is entering the creek, and at least four creek sample points in between aren’t showing any benzene. The contaminated groundwater also is far upstream from his well and shouldn’t reach it underground, Walker said.
The creek also is the source for the town of Parachute’s irrigation supply, but no benzene has been detected at the diversion point.
Benzene in the creek Thursday fell to 4.7 ppb at the area of highest creek contamination.
Williams plans to seek state approval for upgrades to a treatment system to more quickly and thoroughly remove benzene in groundwater before the water enters the creek.
CDPHE spokesman Mark Salley warned Friday the change could temporarily boost benzene levels in the creek “as residual groundwater contamination between the treatment systems and the creek is mobilized.”
But it’s expected the benzene would continue to dissipate as it moves downstream, as it has been doing, he said in a news release.