Following a May 1 blast at the Cordero Rojo coal mine near Gillette, WY, which registered as a small earthquake on seismographs, Cloud Peak Energy Inc. is now facing two notices of violation.
The May 1 cast blast at the mine, located 18 miles south of Gillette, shook the ground for miles and activated seismographs as far away as Europe.
The Wyoming Department of Environmental Quality (DEQ) issued two notices of violation for the blast, which could bring a fine of up to $5,000. Additional penalties could occur if Cloud Peak doesn’t submit plans by next month on how to prevent such an accident from occurring again.
The federal Mine Safety and Health Administration also issued a citation, an administration spokesman said, but they have not assessed a penalty yet.
The DEQ violations said the mine intended to set off 26,852 pounds of explosives during a routine cast blast, a procedure designed to knock out large amounts of rock and soil above a coal seam.
However, the department said that upon detonation shortly after 11 a.m., explosives adjacent to the blast area were also accidentally set off, creating a blast in excess of the legal limit of 85,308 pounds of explosives.
The explosion was so large that some Gillette residents felt the ground shake from 16 miles away. Several European earthquake detection stations registered the vibrations from the blast, and seismographs at the University of Utah, 400 miles away from the Cordero Rojo mine, initially recorded the shock as a magnitude 4.3 earthquake with an epicenter north of Green River, 50 percent closer than where the actual explosion took place.
The state suspended the blaster in charge of the explosion and the blaster’s assistant for at least 60 days.