Benzene found 1,400 feet from leak site
High benzene levels in groundwater have been detected about 1,400 feet downstream of the presumed source of a hydrocarbons leak northwest of Parachute, the state Department of Natural Resources said today.
That’s the farthest such reported detection from the site, as the area of known contamination continues to grow.
A new monitoring well about 10 feet from the creek found benzene at 340 parts per billion, the state said. The drinking water standard for benzene is 5 ppb or less.
The state said six new monitoring points have been installed in that same area, and crews continue to pump from trenches along the north side of the creek to enhance groundwater flow away from the creek.
Some hydrocarbons were recovered today, but the amount was still being determined.
About 6,000 gallons of hydrocarbons have been recovered so far.
Williams this week said the leak resulted from a faulty pressure gauge on a valve set for a natural gas liquids line leaving its nearby gas processing plant. The state says that while Williams’ explanation may explain the contamination, it is continuing to investigate.
The state today also said diesel-range organics have been detected at between 0.71 and 0.49 parts per million in the creek about two miles downstream from the leak site, where the town of Parachute diverts water for an irrigation reservoir. However, it noted that recent creek sampling in the investigation area has shown no such detections.
DROs have been detected intermittently upstream of the leak site, and may come from sources such as stormwater runoff from roads. The state notes that several industrial sites lie between the reservoir diversion point and the leak site.