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Cleanup of Clark gas well blowout advances
By Buzzy Hassrick
This document was published online on Wednesday, February 27, 2008
A clean-up plan for contamination from the natural gas well blowout in Clark will be submitted May 1 to the state.
About 20 residents listened Tuesday night to a report about the work to identify the extent of the contamination.
“Overall, I think we're making good progress,” said Michael Bullock of Terracon Consultants. “The data are coming in.”
Terracon and Energy Laboratories, both of Billings, are working for Windsor Energy Group of Oklahoma City, owner of the well on Line Creek, which agreed to a voluntary mitigation plan.
The blowout occurred Aug. 11, 2006, and caused the temporary evacuation of 25 homes. So far, one water well has shown contamination, and it's 1,500 feet from the blowout.
In November a granulated carbon system put on the well started removing hydrocarbons and producing potable water, Bullock said. It's sampled monthly.
Terracon has installed 44 monitoring wells with 59 spots for testing, Bullock said. Some wells have more than one testing point.
The company also installed 23 wells in a line that are 40 feet apart where they propose to aerate the groundwater, he said. The pumping will strip out the contaminants and also provide oxygen that encourages microbes to eat the hydrocarbons.
The process could mean Terracon has to get air permits from the state, Bullock added.
The aeration system was installed as an interim measure, “because the contamination was moving faster than we'd like to see,” said Kathy Brown, project manager for the state Department of Environmental Quality. “We do these all across the country, and they're effective.”
Samplings also are being taken on the creek.
“We haven't found an impact in the creek,” Bullock said, though he added that possibly contaminated water hasn't reached the drainage yet.
“We've put quite a bit of effort into establishing the geology of the site,” Bullock said.
The creek runs on bedrock, said geologist Dan Nebel with Terracon. Above the bedrock, he said, lies “valley fill” comprising unconsolidated sediments that are permeable and create a shallow aquifer.
“The valley fill is where the impact would be,” Nebel said. The contamination is occurring in a radial pattern, he added.
All but one spring is showing contamination, Brown said. It's not in the surface matter, Bullock said.
“We're not seeing any significant contamination in the soils,” he said.
The aquifer's characteristics will facilitate the design of a remediation system.
“The shallow aquifer will be easy to treat,” Bullock said.
The proposed treatment will deal with a number of compounds identified as ingredients from Windsor's drilling fluids and the blowout, Andy Valkenburg of Energy Laboratories said. He gave a lengthy explanation of volatile and semi-volatile compounds listed in long reports.
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