DNR: No Blasting Violations at Hanson Quarry Monday; So What Rocked the Area?

Blasting and quarry operations performed at the Hanson Material Service quarry in McCook were within statutory limits Monday according to the Illinois Department of Natural Resources (IDNR), which conducted a two-day inspection following the ground-shaking seismic event that the U.S. Geographic Survey (USGS) blamed on a quarry blast. 

The IDNR's Office of Mines and Minerals sent out a release Wednesday afternoon at the conclusion of their review of Hanson's blasting records and measurement readings.

“The Office of Mines and Minerals takes the proper handling and use of explosives very seriously. In this instance, our inspection found no violations of state law,” blasting and explosives unit chief Mike Falter said.

Illinois state regulations limit vibrations from surface blasting to 1 inch per second at the nearest protected structure, the IDNR's release reads. Measurements taken at the protected structure nearest to the Hanson quarry on Monday showed maximum blast vibrations of .35 inches per second.

The IDNR release states that the seismic event that shook the western suburbs took place seven seconds after Hanson quarry blast. 

“Our review of quarry records does show measurement equipment picked up vibrations from a second and separate event approximately seven seconds after the initial blast," Falter said. "What this secondary event was, or what caused it, is outside our regulatory expertise.” 

U.S. Rep. Dan Lipinski (D-IL) said Wednesday he formally requested the U.S. Department of Labor and the Bureau of Alcohol, Tobacco and Firearms begin an investigation into the circumstances surrounding the seismic event.

"Residents of the area deserve some answers," Lipinksi said.

The Village of La Grange released its own statement Wednesday, before the IDNR release went out, saying that La Grange officials and those of neighboring communities had planned to meet with Hanson representatives next week to discuss Monday's seismic event. 

The village statement also said Hanson's quarry operations would be halted until that meeting.

For more on the rules that govern quarry blasting, visit the IDNR's website.