The collapse of a retaining bluff near We Energies’ coal-fired Oak Creek Power Plant on Monday morning sent debris, dredging equipment, and parts of a ravine filled with coal ash more than 50 years ago spewing into Lake Michigan.

No injuries have occurred, nor has output been affected from the 2,365-MW Oak Creek Power Plant, which is located on more than 400 acres of land on the border of Milwaukee and Racine counties on the Lake Michigan shore. The debris field is reportedly 50 to 80 yards wide and stretches 120 yards long.

Employees at We Energies were reportedly building an air quality control facility when the ground gave way at 11:00 a.m. on Monday. Wisconsin’s Department of Natural Resources (DNR) and the Occupational Safety and Health Administration (OSHA) continue investigating the spill’s cause as crews clean up the site. Clean-up activities include draining a retention pond uphill of the bluff for safety reasons. Milwaukee television station WTMJ reported on Tuesday that the area around the bluff may still not be safe, as “trailers hang over the edge and some structures are partially on land.”
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According to the National Weather Service, the region had not seen any heavy precipitation, receiving only 0.23 inches of rain on Sunday. The Milwaukee Journal Sentinel quoted University of Wisconsin-Milwaukee geology professor Tom Hooyer as saying that the failure could have more likely been caused by seepage from a high water table than from erosion from the lake. He speculated that water from an unlined retention pond uphill from the bluff could have loosened nearby soil.

Construction on or around the site also could have caused the bluff to become unstable, the Journal-Sentinel quoted DNR’s waste supervisor Frank Shultz as saying. The state regulatory body told the newspaper that ongoing construction of the $900 million pollution control project at the original Oak Creek power plant, which had been approved by the Wisconsin Public Service Commission in 2008, did not warrant a detailed environmental impact statement or environmental assessment.

The spill occurred just weeks after the U.S. House voted 267-144 with 37 Democrats approving the measure to impede the Environmental Protection Agency (EPA) from proceeding with its May 2010 proposed rule to regulate coal ash residuals. A companion measure has since been introduced in the Senate. The bills essentially prohibit the EPA from classifying coal ash residuals as hazardous waste and requires states—as opposed to the EPA—to create plans to manage coal ash and empowers them to enforce them.

On Monday, responding to the Oak Creek spill, Mary Anne Hitt, director of Sierra Club’s Beyond Coal Campaign, lambasted Congress for blocking the EPA from regulating coal ash, a measure the agency has spearheaded since Tennessee Valley Authority’s Kingston coal ash spill in December 2008. She said the spill was a “tragic reminder of why the status quo is not good enough.”

"The Senate should immediately stop work on its bill to block the EPA from protecting Americans from toxic coal ash, and our Senators should urge the EPA to finalize its rulemaking process that began in 2009, received hundreds of thousands of comments in support, and has still not been finalized because of industry pressure,” she said.

Sources: POWERnews, WTMJ, Milwaukee Journal Sentinel, We Energies, DNR