An estimated 2,500 cubic yards of coal ash and soil - enough to fill more than 208 large dump trucks - was pushed into Lake Michigan in Monday's bluff collapse and landslide at the We Energies' Oak Creek Power Plant, a state environmental official said Friday.
The slide carried 25,000 cubic yards of ash and soil down the slope and about 10% of the load washed into the lake, said Ann Coakley, director of the waste and materials management bureau for the Department of Natural Resources.
Samples of coal ash and lake water were collected this week for testing to determine the environmental impact of the ash slide, officials said. Tests will show the levels of heavy metals and other contaminants in the ash.
Test results were not available Friday, Coakley said.
The plume of ash, soil and debris left behind in the wake of Monday's landslide stretched 120 yards long and up to 80 yards wide. The slide is immediately south of a $900 million air quality control facility under construction at the power plant. The building was not damaged.
Workers began digging ash and soil Friday out of two ponds on the Lake Michigan shore, We Energies spokesman Barry McNulty said. The excavation will continue for several days.
The sediment ponds are needed to store temporarily a mix of coal dust and water from cleaning of equipment inside the power plants.
Cleanup of ash and soil from the bluff collapse that is west of a stone berm built on the shore is to begin next week, he said. The berm was constructed after the landslide to help contain debris on the shore.
Ash and soil is being disposed of at a landfill on the power plant property. Cleanup east of the berm to the lake was completed Thursday.
Lifting large debris out of the lake will begin next week, McNulty said.
Divers could get started this weekend marking underwater locations of storage containers, a vehicle and construction equipment pushed into the lake from the force of the ash and mud slide, We Energies spokesman Brian Manthey said.
Removal of coal ash and soil in the lake will be coordinated with federal and state environmental regulators. No decision was made as of Friday on whether the ash and soil would be dredged from a vessel on the lake or scooped up with machinery on land, McNulty said.
U.S. Coast Guard officers trained as pollution responders have driven on land five miles north and five miles south from the plant each day this week. They have not spotted debris or fuel slicks floating away from the property, said Lt. j.g. Brian Dykens, a spokesman for the Lake Michigan sector office in Milwaukee.
Daily air flights by a Coast Guard auxiliary unit out of Milwaukee have not spotted debris fields or fuel slicks on the water, Dykens said.
Those official observations were disputed by a local resident. Maureen Wolff of Caledonia said she observed a line of black water near the shoreline about one-half mile south of the landslide on Friday morning.
An investigation into the cause of the bluff collapse is continuing, We Energies officials said.
The collapse occurred at a ravine that had been filled in the 1950s with coal ash from the power plant.
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