Blasting Complaint - 9/5/2017 (2)

V
Energy, Mineral &
LandResources
ENVIRONMENTAL QUALITY
September 5, 2017

RE: - Blasting Complaint
Bamboo Road Quarry
Permit No. 95-03
Watauga County
Dear Ms.
ROY COOPER
Governor
MICHAEL S. REGAN
Secretary
TRACY DAVIS
Director
Our office has completed its review of Radford Quarries Inc.'s blasting information, including blast
reports and seismograph recordings, related to the September 2, 2016 through July 21, 2017 blasts
conducted at its Bamboo Road Quarry. It was found that Radford Quarry Inc. was in compliance with the
blasting requirements of its mining permit during the period in question.
All peak particle velocities (recorded and calculated), a measurement of ground vibration with units
in inches per second (ips), were at or below the maximum allowable limits specified in Radford Quarries
Inc.'s mining permit.
All airblast readings (recorded and calculated), a me ' asurement of the atmospheric pressure wave
(overpressure) with units in psi or dBL, 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 dBL 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 [phone].
S' I erely,
?y E. avis, PE, CPM
D Ul ctorr N
i ctor. EML�R
TED/jw
cc: Mr. Matthew Gantt, PE
State of North Carolina I Environmental QUallty I Energy, Mineral and Land [Resources
512 N. Sabsbur� StreeL 1 1612 Mail Ser\,ice Center I Raleigh. North Carolina 27699-1612
9197079200