Blasting Complaint - 9/15/2017

Energy, Mineral &
Land Resources
ENVIRONMENTAL QUALITY
September 5, 2017
Dr. D J Cecile
Radford Quarries, Inc.
PO Box 2071
Boone, North Carolina 28607
RE: Blasting Complaint
Bamboo Road Quarry
Permit No. 95-03
Watauga County
Dear Dr. Cecile:
ROY COOPER
Governor
MICHAEL S. REGAN
Secretary
TRACY DAVIS
Director
This office has completed its review of the shot records you previously submitted for the
September 2, 2016 through July 21, 2017 blasts at the Bamboo Road Quarry. Your company has
been found to be in compliance with the blasting conditions outlined in Mining Permit No. 95-03.
However, our analysis of your company's blast records and seismograph reading for the
September 2, 2016 blast noted that the longitudinal component of ground vibration for this blast was
close to exceeding the US Bureau of Mines R188507 limits established in your mining permit's blasting
conditions. In addition, the March 15, 2017 blast did not trigger the seismograph and likely would have
based upon the results of this office's theoretical computations for both ground vibration and air
overpressure (calculated to be 0.55 inches per second and 126.8 decibels). Thus, it appears that the
seismograph trigger level may need to be adjusted to generate an accurate reading for future blasts.
Although there does not appear to be a violation of the blasting requirements of Mining Permit
No. 95-03, this office requests that your company address the following items:
a) Request that your blasting consultant reevaluate and make any necessary adjustments to the
design of the blast layout and number of explosives used to lower the ground vibration levels
during future blasts at this facility-,
b) Remember that your mining permit's blasting conditions require that your company immediately
contact this office should any blast at this facility exceed the ground vibration and/or air
overpressure limits specified in the mining permit;
c) Request that your blasting consultant evaluate and adjust as necessary the trigger level on
your seismograph to ensure it is properly set to record ground vibration and air overpressure for
all future blasts; and
d) To ensure that the above issues have been addressed, please submit the next three
blast records and seismograph readings to this office for its review.
State of North Carolina I Divironmental QU@hty I Energy, Mineral and Land Resources
512 N. Salisbury Street i 1612 Mail Service Center I Raleigh, North Carolina 27bl)9-1612
919 707 (4200

Dr. D J Cecile
Page 2
Thank you for your continued cooperation. If you should have any questions on the above,
please contact me at [phone].
SiWerely,
TED/jw
cc: Mr. Matthew Gantt, PE
avis, PE, CPM
EMLR