Laserfiche WebLink
2801Youngfield Street, Suite 171 <br /> uWave Golden, CO 80401-2266 <br /> Monitorin 303-456-5638 <br /> , � g Toll Free 888-456-5638 <br /> Systems, ��C. Fax 303-456-5639 <br /> www.uwavems.com <br /> Colorado Quarries <br /> Mr. Aaron Tezak <br /> 270 S 15�' Street <br /> Canon City, CO 81212 <br /> Mr. Tezak <br /> uWave Monitoring Systems, LLC (UMS) was retained by Colorado Quarries to monitor a blast <br /> at the Silver Cliff, Colorado black obsidian mine. Cory Loukides of UMS monitored the blast on <br /> December 22, 2021 at 11:06. <br /> An Instantel Blastmate III seismograph was used to monitor at the property line of the closest <br /> occupied structure located at 1455 Oak Creek Grade, Silver Cliff, CO 81252. The seismograph <br /> was located 860 feet east of the blast and measured a peak particle velocity (PPV) of 0.0406 <br /> inches per second (in/s) at 20.5 Hertz (Hz). The peak sound pressure level (PSPL) recorded <br /> during the blast was 118.5 dB(L) or 0.002429 pound per square inch. <br /> The PPV and PSPL were well below the United States Bureau of Mines (USBM) and Office of <br /> Surface Mining and Reclamation (OSMRE) levels for damage to drywall and window glass. At a <br /> frequency of 20.5 Hz the PPV for possible damage is approximately 1.0 in/s. The regulatory <br /> limit for PSPL is 133 dB(L). <br /> Attached to this letter are the vibration record and calibration certificates for the seismograph <br /> used to monitor the blast. Please contact me with any questions or concerns. <br /> Cory Loukides <br /> uWave Monitoring Systems, LLC <br /> 1 <br />