20240729 Blasting Response Letter - Complaintant

ROY COOPER
Governor
ELIZABETH S. BISER
Secretary
WILLIAM E.TOBY VINSON,JR. NORTH CAROLINA
Interim Director Environmental Quality
July 29,2024
Pamela Sages
193 Poplar Woods Drive
Concord,NC 28027
RE: Blasting Complaint
Cabarrus Quarry
Mining Permit No. 13-27
Cabarrus County
Yadkin-PeeDee River Basin
Dear Ms. Sages:
Our office has completed its review of Vulcan Construction Materials' blasting information, including blast
reports and seismograph recordings,related to the June 18,2024 through July 3,2024 blasts conducted at the
Cabarrus Quarry. It was found that Vulcan Construction Materials was in compliance with the blasting
requirements of its mining permit during the period in question.
All peak particle velocities, a measurement of ground vibration with units in inches per second lips), were well
below the maximum allowable limits specified in Vulcan Construction Materials'mining permit. More specifically,
all recorded values were at or below 0.305 ips at the closest offsite occupied structure (the location where
compliance with the permit limits is determined). According to extensive research by the U.S. Bureau of Mines
and others, particle velocities below 0.5 ips effectively eliminate the possibility of any structural damage.
All airblast readings,a measurement of the atmospheric pressure wave(overpressure)with units in psi or dB,were
also below the maximum allowable limits specified in the mining permit and well below the U. S. Bureau of Mines'
recognized level of 164 dB for prevention of glass breakage. A key point worth noting is that glass breakage occurs
at much lower levels of overpressure than structural damage, such as cracking plaster.
Thank you for your interest and patience in this matter. Hopefully, I have answered your concerns adequately. If
you should have any additional questions or concerns, please contact me at(919)707-9220.
Sincerely,
Ke Jonas
Assistant State Mining Engineer
cc: Jerry Eplin, P.E.
North Carolina Department of Environmental Quality I Division of Energy,Mineral and Land Resources
512 North Salisbury Street 11612 Mail Service Center I Raleigh,North Carolina 276 9 9-1612
�^•°�� 919.707.9200