HomeMy WebLinkAbout20210225 ADI noiseROY COOPER
Governor
MIC14AEL S. REGAN
Secretary
BRIAN WRENN
Director
Mr. Samuel T. Bratton
President and CEO
Wake Stone Corporation
P O Box 190
Knightdale, NC 27545
NORTH CAROLINA
Environmental Quality
February 25, 2021
Subject: Cary (Triangle) Quarry's Draft Noise Study
Mining Permit No. 92-10
Wake County
Neuse River Basin
Dear Mr. Bratton:
I would like to take this opportunity to thank you and your staff at Wake Stone for allowing me and the
staff of DEMLR the opportunity to review and discuss your proposed draft of the Wake Stone Triangle
Quarry Expansion Acoustical Study.
General Comments:
A 10dBA increase/decrease seems to be coarse measure of significant impact. The Division
understands that this standard is used by NCDOT and other agencies evaluating noise impacts.
However, considering a state park is adjacent to the proposed quarry, the Division believes a more
conservative standard should be considered. Please provide further justification for a use of this
standard.
During our discussion, Wake Stone described several conservative assumptions that were included
in the model. Please provide a comprehensive list of these assumptions.
Report Specific Comments:
• Please include further discussion of the usage factors for equipment noise implemented in the
modeling (p. 18).
• On p. 17, a ground factor of G=0.5 was used for the quarry. Please provide a discussion explaining
why this is appropriate.
• Table 4, p. 20 — Please provide a detailed explanation of how the "existing 1-40 traffic" was
modeled.
• Blasting noise discussion p. 22 — Please explain how the blasting noise ranges compare similarly
between the existing and proposed pits. The maximum blasting noise from the proposed pit
seems significantly higher than the existing pit.
• Footnote of Table 6, p. 22 — Please provide an explanation of how blast noise is not used for
compliance purposes. Per our discussion, you indicated that the blast noise was included in the
hourly averaging of the study. Please describe this.
• Please describe why back-up alarms were not included in noise study.
D_EQ�� North Carolina Department of Environmental Quality I Division of Energy. Mineral and land Resources
512 North Salisbury Street 1 1612 Mail Service Center I Raleigh, North Carolina 27699-1612
919.707.9200
Figure. 12 legend — Please provide color blocks for different dB ranges. It is difficult to discern
colors using lines in legend.
Figure. 14 — Please provide transparency for the color ranges so that the base layer map and
landmarks can be seen.
Please contact me if any further clarifications concerning the above are needed. I can be reached at:
919-707-9228.
Sincerely, _
David Miller
State Mining Engineer
CC. Bill Denton PE., RRO