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OBSERVATIONS <br />PERMIT #: M- 1977 -210 <br />INSPECTOR'S INITIALS: BMK <br />INSPECTION DATE: June 5, 2012 <br />The Division conducted a blast monitoring inspection of the site on 6/5/12, as a follow up to our citizen's complaint <br />inspection of the site on 5/18/12. The Division had made a request to the operator that the Division be present during the <br />next blast. Present during the inspection were Tom Kaldenbach and Berhan Keffelew representing the Division, and Mac <br />Schafer representing the operator. The main purpose of this inspection was to observe the operator's method of <br />monitoring blasts and to determine if blasting was being conducted within the limits approved under Technical Revision # 1 <br />dated 7/24/2000. When Technical Revision # 1 was approved, the blast monitoring limits were set at 1.0 in /sec for peak <br />particle velocity and 133dB for air blast. <br />On 6/5/12 around 1:27 p.m. the operator conducted a blast, consisting of 74 holes in area AP, the current active mining <br />area. The Division measured the blast's ground motion and air overpressure (airblast) using an Instantel Minimate ground <br />motion and airblast monitor (seismograph) at 4515 Monitor Rock Dr. This monitoring location is located approximately <br />1320 feet from the blast. <br />A triaxial geophone was attached to the Minimate for measuring ground motion and an overpressure microphone was <br />attached for measuring airblast. The microphone was protected with a foam wind screen. The geophone of the <br />seismograph was coupled to the soil on the ground surface with spikes. The internal self -check routine of the seismograph <br />indicated all components of the seismograph were functioning properly, but results from the seismograph are considered <br />preliminary because the seismograph was 15 months past the date recommended by the manufacturer for calibration. <br />From the monitoring location, the blast was audible and moderate ground vibration was apparent. The results of the <br />monitoring were: peak particle velocity 0.11in /sec, airblast was recorded at 58.6 dB(L), and acceleration of 0.018g. The <br />operator's consultant recorded 0.13 in /sec for peak particle velocity and 116.3 dB(L) for airblast. The Division's airblast <br />recorded data of 58.6 dB(L) was significantly lower than the 116.3 dB(L) recorded by the operator's consultant. The blast <br />appeared to be in compliance with the blasting monitoring limits of 1.0 in /sec peak particle velocity and 133 dB for air blast. <br />The Division will have its seismograph calibrated and then re- evaluate compliance of a future blast. <br />Page 2 of 3 <br />