2017-10-05_PERMIT FILE - M2017049 (41)

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A misfire is the complete or partial failure of a blast hole to detonate as planned. With advancements in product quality and blast technology, misfires rarely happen, however in the event of a misfire the lead blaster will: • Not release the immediate blast area for return to work. • Wait 30 minutes before completing a more thorough investigation of the cause of the misfire. o Depending on the location of the blast, the lead blaster, at his discretion, can release areas not in the immediate area of the blast while waiting the required 30 minutes. This may include the access corridor and other facilities on the site. • If the investigation reveals the detonator can be re-used and re-shot,the blast area will be cleared again, blast guards reestablished, and the blast warning procedure will be reinitiated and the detonator blasted. • If the detonator cannot be re-used and blasted, the area will be secured and all mining personnel warned of the hazard. The area will be carefully excavated under the supervision of the lead blaster or quarry manager until the blasting cap and booster are located. Blast Monitoring Procedures— As part of Hitch Rack Ranch Quarry's blasting plan, all blasts will be monitored using several methods. They are as follows: • Blasts will be video recorded, if weather conditions permit. • Seismic instrument(s) will be used to measure ground vibration and peak particle velocity. The proposed maximum peak particle velocity will be one half(1/2) inch per second measured at the seismic instrument set up nearest to the closest structure. All attempts will be made to keep peak particle velocities well below the proposed maximum allowable limits. Monitoring equipment will have a frequency range of 2 to 250 Hz. • Microphone(s) will be used to measure air over pressure (air blast) and noise. The proposed maximum decibel (dB) level for air over pressure will be 130 dB measured at the seismic instrument set up nearest to the closest structure. Industry standard for air over pressure maximum (dB) level is 133 dB. All attempts will be made to keep air over pressure levels well below the proposed maximum allowable limits. Monitoring equipment will have a frequency range of 2 to 250 Hz. All blasts will be monitored with three separate monitoring units made up of a seismograph, geophone (seismic unit), and a microphone. The locations for these units are described below: • One stationary unit will be located at the western edge of the property in the location of the western gate along Little Turkey Creek Road. • The second relatively stationary unit will be located on the eastern edge of the property adjacent to the eastern gate along Little Turkey Creek Road or on the quarry access road. The location will be determined based on the closest structure to the blast.