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RULE 4 PERFORMANCE STANDARDS <br /> <br />Rule 4 Performance Standards 4-28 Revision Date: 4/9/25 <br /> Revision No.: MR-261 <br />seismograph/microphone with a low frequency limit of 2 Hz which corresponds to an airblast <br />standard of 133 dB (peak). Records of airblast monitoring will contain the information required <br />by Rule 4.08.5(17). This information will include either a recording of the calibration signal of <br />the monitoring instrument’s gain setting at the time of each blast, or certifications of the <br />instrument’s annual calibration. <br /> <br />Colowyo will conduct blasting to prevent injury to persons and damage to public or private <br />property outside the permit area. Colowyo will insure that the maximum peak particle velocity will <br />not exceed the criteria as prescribed by utilizing the equation found in Rule 4.08.4(10) (b) (i) when <br />conducting blasting operations that could affect any dwelling, public building, school, church, or <br />commercial or institutional building. As shown in the Blasting Analysis Map (Map 26A) Colowyo <br />has determined the maximum pounds of explosives per 8ms period of time for variable distance <br />from any such structures. <br /> <br />The number of blast holes detonated per 8ms period will be calculated according to the equation <br />in Rule 4.08.4(10)(c)(i) in order to determine the maximum weight of explosive that can be <br />detonated within any eight ms period. <br /> <br />4.08.5 Records of Surface Blasting Activities <br /> <br />Colowyo will record all blasts including coal, overburden, and overburden pre-split blasts in a <br />format as shown in Section 2.05, Figure 2.05-2, Blasting Report, which conforms to the <br />requirements of 4.08.5. Conducting blasting operations in accordance with the equation in <br />4.08.4(10)(c)(i) deems peak particle velocities from blasting to be within the regulatory limits <br />described in 4.08.4(10). Periodic airblast monitoring occurs at Colowyo. The monitor is located <br />along Moffat County Highway 13 at the Durham/Ott Ranch. Records of airblast monitoring <br />described on page 2.05-30 will contain the information required by Rule 4.08.5(17). This <br />information will include either a recording of the calibration signal of the monitoring instrument’s <br />gain setting at the time of each blast, or certifications of the instrument’s annual calibration. <br /> <br />4.08.6 Seismographic Measurements <br /> <br />Colowyo will use the explosives equation found in Subsection 4.08.4 (10)(b)(i) to limit the number <br />of blast holes per 8ms period of time such that the peak particle velocity limit of one inch per <br />second will not be exceeded. <br /> <br />On June 19 and 20, 1979 initial seismic monitoring of shots at the Colowyo operation was <br />conducted. The results of this seismographic work are set forth in Exhibit 14, Seismographic <br />Measurements. <br /> <br />4.09 DISPOSAL OF EXCESS SPOIL AND UNDERGROUND DEVELOPMENT FILL <br />WASTE <br /> <br />To develop the West Pit and Section 16 Pit, it was necessary to construct two excess spoil fills <br />from material in the initial cuts. The designs detail for these fills is presented in Exhibit 19 – <br />Geotechnical Investigations, West Pit Fill and Section 16 Fill.