Laserfiche WebLink
RULE 4 PERFORMANCE STANDARDS <br />Colowyo will control air blast from its blasting operations within the permit area so it does not exceed <br />the values specified by the chart set forth in Rule 4.08.4(6). The same design factors utilized to control <br />the seismic effects of blasting (i.e.: the use of numerous surface delays to "spread" the shots out over <br />time, particularly near residences) is also very effective in controlling airblast. Additionally, to keep <br />airblast to a minimum Colowyo also routinely 1) utilizes reduced weight (12 grain Zap) surface primer <br />cord, 2) uses proper stemming material, 3) uses a proper stemming weight, 4) avoids overdigging the <br />front row of holes and 5) avoids overloading the front row of holes. <br />Colowyo does perform event triggered monitoring. However, Colowyo will not commit to daily <br />monitoring due to unforeseen circumstances where the seismograph monitoring unit may be getting <br />repaired or calibrated. Colowyo employs an Instantel Inc. Minimate Plus seismograph/microphone <br />with a low frequency limit of 2 Hz which corresponds to an airblast standard of 133 dB (peak). <br />Records of airblast monitoring 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 gain <br />setting at the time of each blast, or certifications of the instrument's annual calibration. <br />Colowyo will conduct blasting to prevent injury to persons and damage to public or private property <br />outside the permit area. Colowyo will insure that the maximum peak particle velocity will not exceed the <br />criteria as prescribed by utilizing the equation found in Rule 4.08.4(10) (b) (i) when conducting blasting <br />operations that could affect any dwelling, public building, school, church, or commercial or institutional <br />building. As shown in the Blasting Analysis Map (Map 26) Colowyo has determined the maximum <br />pounds of explosives per 8ms period of time for variable distance from any such structures. <br />The number of blast holes detonated per 8ms period will be calculated according to the equation in Rule <br />4.08.4(10)(c)(i) in order to determine the maximum weight of explosive that can be detonated within any <br />eight ms period. <br />4.08.5 Records of Surface Blasting Activities <br />Colowyo will record all blasts including coal, overburden, and overburden pre -split blasts in a format as <br />shown in Section 2.05, Figure 2.05-2, Blasting Report, which conforms to the requirements of 4.08.5. <br />Conducting blasting operations in accordance with the equation in 4.08.4(10)(c)(i) deems peak particle <br />velocities from blasting to be within the regulatory limits described in 4.08.4(10). Periodic airblast <br />monitoring occurs at Colowyo. The monitor is located along Moffat County Highway 13 at the <br />Durham/Ott Ranch. Records of airblast monitoring described on page 2.05-30 will contain the <br />information required by Rule 4.08.5(17). This information will include either a recording of the <br />calibration signal of the monitoring instrument's gain setting at the time of each blast, or certifications of <br />the instrument's annual calibration. <br />4.08.6 Seismographic Measurements <br />Colowyo will use the explosives equation found in Subsection 4.08.4 (10)(b)(i) to limit the number of <br />blast holes per 8ms period of time such that the peak particle velocity limit of one inch per second will not <br />be exceeded. <br />On June 19 and 20, 1979 initial seismic monitoring of shots at the Colowyo operation was conducted. The <br />results of this seismographic work are set forth in Exhibit 14, Seismographic Measurements. <br />Rule 4 Performance Standards 4-30 Revision Date: 8/28/17 <br />Revision No.: TR -115 <br />