CLARK - Plans to clean up the groundwater around a gas well that burst in 2006 have been accelerated now that benzene has turned up in a residential water well.
Excess pressure caused the blowout near a small rural subdivision a few miles south of the Montana line. About a dozen residents evacuated amid fear of an explosion or fire.
Workers plugged the 8,000-foot well with mud and homeowners returned after a few days. But concerns lingered about groundwater contamination.
Tests last year showed elevated levels of benzene in the well of Mel and Connie King, who were warned not to drink their water. Oklahoma City, Okla.-based Windsor Energy, which drilled the well, has since installed filtration equipment to remove contaminants and make the couple's water safe to drink.
Groundwater contamination also has turned up in water from monitoring wells. Environmental engineers have been trying to determine the extent of the contamination.
Plans had called for cleanup work to begin in April 2009, but that timeframe has been sped up since benzene turned up in the King well.
Windsor now is expected to deliver to the state Department of Environmental Quality by May 1 a report outlining different options for cleaning up the groundwater in the area, according to environmental consultant Michael Bullock.
Bullock works for Terracon, a Billings, Mont., company helping Windsor with the monitoring and cleanup. Terracon is working to install equipment that would pump air into the groundwater to help disperse chemicals out of the water.
Bullock said Terracon has data from 58 monitoring well points and is testing 20 private water wells, including some more than three miles from the blowout site.
He said the area has both shallow and deep aquifers.
"The aquifer characteristics we're seeing allow us to design a system to remediate the groundwater on the site," Bullock said of the shallow aquifer.
He said the deeper aquifer would be more difficult to clean up.
Some residents have asked Windsor and the Department of Environmental Quality to produce a map of groundwater flow in the area. They say that would provide a better understanding of how the groundwater pollution could spread.
Terracon officials say they have a map based on data from monitoring wells, but that data doesn't include the residential areas. They say data from residential water wells, obtained with the consent of homeowners, could help create a flow map of the subdivision.