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Home My WebLink About20230303_Blasting_Complaint_Response_01-10 P��{H�SiA1£a ROY COOPER 3 Governor ELIZABETH S.BISER Secretary �AM° * DOUGLAS R.ANSEL NORTH CAROLINA Interim Director Environmental Quality March 3,2023 Mr. Chad Threatt Alamance Aggregates, LLC PO Box 552 Snow Camp,NC 27349 RE: Blasting Complaint Alamance Aggregates Quarry Mining Permit No. 01-10 Alamance County Cape Fear River Basin Dear Mr. Threatt: The review has been completed on the shot records you previously submitted for the February 8,2023 blasts at the Alamance Aggregates Quarry. Your company has been found to be in compliance with the seismic and air overpressure blasting conditions outlined in Mining Permit No. 01-10. However, during a review of your records and your permit it was determined that condition 8.N, as written, does not account for a difference in calculating scale distance when using electronic detonators versus non-electric detonators. In order for the condition in your permit,as written,to match the proposed condition in the application, the permit must be modified. Please let us know as soon as possible regarding your plans to modify the permit. Thank you for your continued cooperation. If you should have any questions on the above, please contact me at (919)707-9220. Sincerely, Adam Parr,PE Assistant State Mining Engineer cc: Ms. Tamera Eplin,PE Q � 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 vC)R7'CaROI iNA f 919.707.9200 P��{H�SiA1£a ROY COOPER 3 Governor ELIZABETH S.BISER Secretary �AM° * DOUGLAS R.ANSEL NORTH CAROLINA Interim Director Environmental Quality March 3, 2023 Judy Shaver 9022 Whitehouse Court Snow Camp,NC 27349 RE: Blasting Complaint Alamance Aggregates Quarry Mining Permit No. 01-10 Alamance County Cape Fear River Basin Dear Ms. Shaver: Our office has completed its review of Alamance Aggregates, LLC's blasting information, including blast reports and seismograph recordings,related to the February 8,2023 blasts conducted at the Alamance Aggregates Quarry. It was found that Alamance Aggregates, LLC was in compliance with the seismic and air overpressure blasting requirements of its mining permit during the period in question. However, it was determined that there was a discrepancy between a condition in the final permit and the permit application. The agency is reaching out to the permittee to determine next steps. At no time did this discrepancy subject the public to any heightened risk. All peak particle velocities, a measurement of ground vibration with units in inches per second (ips), were well below the maximum allowable limits specified in Alamance Aggregates,LLC's mining permit. More specifically, all recorded values were at or below 0.14 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. More specifically,all recorded values were at or below 127.9 dB at the closest offsite occupied structure (the location where compliance with the permit limits is determined). 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, Adam Parr,PE Assistant State Mining Engineer cc: Ms. Tamera Eplin,PE 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 NORM CAROLINA - oepaMemotenmmnmemaiQuality /`� 919.707.9200 P��{H�SiA1£a ROY COOPER 3 Governor ELIZABETH S.BISER Secretary �AM° * DOUGLAS R.ANSEL NORTH CAROLINA Interim Director Environmental Quality March 3, 2023 Dr. Timothy J. &Celeste M. Mulrooney 9065 Whitehouse Ct. Snow Camp,NC 27349 RE: Blasting Complaint Alamance Aggregates Quarry Mining Permit No. 01-10 Alamance County Cape Fear River Basin Dear Ms. Shaver: Our office has completed its review of Alamance Aggregates, LLC's blasting information, including blast reports and seismograph recordings,related to the February 8,2023 blasts conducted at the Alamance Aggregates Quarry. It was found that Alamance Aggregates, LLC was in compliance with the seismic and air overpressure blasting requirements of its mining permit during the period in question. However, it was determined that there was a discrepancy between a condition in the final permit and the permit application. The agency is reaching out to the permittee to determine next steps. At no time did this discrepancy subject the public to any heightened risk. All peak particle velocities, a measurement of ground vibration with units in inches per second (ips), were well below the maximum allowable limits specified in Alamance Aggregates,LLC's mining permit. More specifically, all recorded values were at or below 0.14 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. More specifically,all recorded values were at or below 127.9 dB at the closest offsite occupied structure (the location where compliance with the permit limits is determined). 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, Adam Parr, PE Assistant State Mining Engineer cc: Ms. Tamera Eplin,PE 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 NORM CAROLINA - oepaMemotenmmnmemaiQuality /`� 919.707.9200