Draft Review Letter - 7/30/2001

North Carolina
Department of Environment and Natural Resources
Michael F. Easley, Governor
William G. Ross Jr., Secretary
Charles H. Gardner, P.G., P.E.
Director and State Geologist

RE: Blasting Complaint
Bamboo Road Quarry
Permit No. 95-03
Watagua County
Dear Mr.
July 30, 2001
A�11�
410
AM
NCDENR
Division of Land Resources
,,�Our officeXs completed its review of Radford Quarries of Boone, Inc.'s blasting
Wo'rmation re19W to the blasts conducted at its Bamboo Road Quarry during the period of April
and May 1 and June 5, 2001. It was found that Radford Quarries of Boone, Inc. was in
complia
,pc with the blasting requirements of its mining permit during the period in question.
49�All peak particle velocities, a measurement of ground vibration with units in inches per
nd (ips), were well below the maximum allowable limit specified in the Bamboo
Road Quarry mining permit. More specifically, all recorded values were at or below 70-pemmt;
I A' Q .0.
All airblast readings, a measurement of the atmospheric pressure wave (overpressure)
with units in psi or dBL, were below the maximum allowable limit at42&4ft'specified in the
Bamboo Road Quarry mining permit and well below the U. S. Bureau of Mine's 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.
However, we did note that increased stemming lengths may reduce elevated airblasts
associated with future blasting efforts. We have brought this to Radford Quarries of Boone,
Inc.'s attention and have suggested that it adjust its blasting practices to further reduce noise
and nuisance complaints from nearby landowners.
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J,rd aliliSection 733-4574 Fax [phone] Geological Survey Section [phone] Fax [phone]
1612 Mail Service Center, Raleigh, North Carolina 27699-1612
OAA�rIV ivision of Land Resources [phone] Fax [phone]
AN EQUAL OP ITY \ AFFIRMATIVE ACTION EMPLOYER - 50% RECYCLED / 10% POST CONSUMER PAPER
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Mr.
Page 2
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 concern, please
contact me at [phone].
Sincerely,
Chris Hite
Assistant State Mining Specialist
Land Quality Section
/ch
cc: Mr. Matthew E. Gantt, P.E.