Previous leaks suspected in Parachute hydrocarbon probe

A continuing investigation is suggesting more than one leak that possibly occurred in the past as sources of liquid hydrocarbon contamination near Parachute Creek northwest of Parachute.

That’s according to Colorado Department of Natural Resources spokesman Todd Hartman, in a daily emailed update Monday to reporters on a situation being investigated by the Colorado Oil and Gas Conservation Commission.

That investigation continues to concentrate on a valve set for a 4-inch-diameter natural gas liquids line owned by Williams.

“The investigation to date has not identified an active source; 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. That is … (a) focus of COGCC’s efforts,” Hartman said.

The recovery trench was dug to protect the nearby creek and help allow for removal of the fluids.

Williams spokeswoman Donna Gray said Monday, “Growing information that we have is pointing to more than one source.”

The 4-inch-diameter pipeline that the valve set serves originates at Williams’ gas plant east of Parachute Creek and goes beneath the creek to tanks on the other side. The plant removes liquids such as ethane and propane from the gas.

The valve set last week became the focus of an investigation that began March 8 when Williams discovered contamination in the pipeline corridor, which holds several lines. Williams was doing location work as it prepares to build a second plant on the same site to remove a greater amount of natural gas liquids.

A historic rather than ongoing leak or leaks would coincide with what remediation crews encountered. Large initial amounts of an unidentified liquid hydrocarbon were removed for several days from the corridor just east of the creek. But the flows then tapered off and the total amount recovered stopped increasing after reaching about 6,000 gallons.

High levels of benzene, a carcinogen, have been found in shallow groundwater just 30 feet from the creek, but tests so far show no sign of contamination in the creek, authorities say.

Gray said Williams today will be using a mechanical probe that can detect benzene and other volatile organic compounds associated with oil and gas development in groundwater and soils. That will help it more quickly delineate the extent of contamination and get a clearer picture of what’s going on, she said.

Williams also has installed more groundwater monitoring wells, and established a fourth monitoring site along the creek, she said.



COMMENTS

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As Carl McWilliams points out in a recent email, the COGCC reported the benzene concentration as 18,000 ppb and this is 18 ppm. Concerned about worker safety, he goes on to ask the question, “I may sound paranoid or just skeptical; but ask yourself this question: Why did the COGCC report the benzene levels in the billions (ppb) instead of the millions (ppm)? “ He lists the link http://www.cdc.gov/niosh/idlh/71432.html and adds a listing of abbreviations used:
NOTE: IDLH = “Immediate danger to life and health”. PEL = “Permissible Exposure Limits”, TWA = “Time Weighted Average” and STEL = “Short Term Exposure Limit”. He also adds the NIOSH note:
Revised IDLH: 500 ppm
Basis for revised IDLH: The revised IDLH for benzene is 500 ppm based on acute inhalation
[Note: NIOSH recommends as part of its carcinogen policy that the “most protective” respirators be worn for benzene at concentrations above 0.1 ppm.
toxicity data in humans [Gerarde 1960].

But this story indicates that Williams is throwing in the towel as to locating a source saying it may be past spillage or whatever. I would offer them a suggestion:
If the valve on the liquids line is not leaking now, maybe it was in the cold weather. The valve, by the picture I viewed is mounted on an above ground riser. If this line proceeds straight from this offset, the cold temperatures can contract the line and put stress on the valve flanges. This could cause a weather induced drip that “cures” itself when temperatures become warmer. The offset works as an expansion joint and temperature ranges cause flex movement. Just saying—-

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