2 March 2012

The cause of the Oak Creek landslide in Wisconsin

Posted by Dave Petley

Long term readers will remember back in November last year I featured on a number of occasions a landslide at the We Energies power station at Oak Creek in Wisconsin (see posts here and here).  An anonymous commenter has highlighted a new report yesterday in the Journal Sentinel that provides more information about the cause and the aftermath. The report notes that:

The state Department of Natural Resources issued a notice of violation to the Milwaukee utility on Thursday saying the agency believes the company violated solid waste regulations when it built a pond in and above a pond built atop a coal ash landfill on the power plant site.

“We have reason to believe that the failure to install a liner in the storm water pond was a significant factor in the bluff collapse,” the DNR said.

The notice of violation indicates We Energies could face fines of up to $5,000 per day.

There are a couple of interesting resources on the WDNR website about this landslide:

At the moment the details of the investigation to which this news report pertains does not seem to be on the DNR website (does anyone have a copy?), but this image of the site (from here) shows that there were two ponds present at the top of the slope before the failure:




Given the nature of the materials at the site (take a look at the post-failure image below), it is surprising to me that there were apparently unlined ponds at the top of this slope: