2019-04-29_PERMIT FILE - C1981019A (6)

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RULE 2 PERMITS Colowyo will use the explosive equation of 4.08.4 (10)(c)(i) to limit the pounds of explosive per 8ms period, similar to that shown on the Blasting Analysis Map (Map 26). Some previous seismographic measurements were made during blasting operations at Colowyo; the results are set forth in Exhibit 14 - Seismographic Measurements. Although seismographic measurements have been made in the past seismographic records will not be used to demonstrate compliance with maximum peak particle velocities. Colowyo has chosen to continue the use of the -scaled-distance formula in Rule 4.08.4(10) (c) (i) to demonstrate compliance with ground vibration requirements. Colowyo will conduct airblast monitoring to ensure compliance with airblast standards. All blast events will be monitored for airblast. On these reports Colowyo will record the name of the company doing the monitoring, the person taking the periodic airblast reading, the name of the person analyzing periodic airblast records, and the distance of the instrument from the blast. Airblast monitoring will be taken from the closest dwelling to the blast area. An Instantel Inc. MiniMate Series III , model DS -477 are maintained at the Durham Ranch and Wilson Creek resident area. Details regarding the monitor specifications are included in Exhibit 14. Airblast monitoring will be recorded on a seismograph report (See Figure 2.05-4) for review by in-house personnel, agency representatives, and requesting publics. The airblast data is recorded under the "PSPL" (Peak Sound Pressure Levels) in decibels (dB). Additional information concerning the use of explosives is found in Section 4.08 Disposal of Excess Spoil As discussed under the heading of Production Methods and Equipment in Section 2.05.3, Colowyo has constructed an overburden disposal structure known as Streeter Fill. During the early operation, overburden had to be placed into the Streeter Fill so that sufficient working area could be developed prior to the placement of subsequent overburden into the mined -out areas. Additional information concerning the Streeter Fill is set forth in Exhibit 12, Experimental Practice Information. In the initial five year permit term, the Streeter Fill was permitted as an Experimental Practice. In 1986, the Experimental Practice designation was terminated. However, in the interest of continuity, information regarding Streeter Fill is still located in the Experimental Practice Section. Two additional pits have be developed within the permit boundary at Colowyo. One of the pits was developed in Sections 15 and 16, south of the existing operation and the other pit, defined as the West pit, will be developed in Section 4. The pit in Sections 15 and 16 was a single seam dragline operation, similar to the current operation in Section 11. To develop the dragline operation, an initial cut must be opened near outcrop. A permanent excess spoil fill of approximately 2 million yd' of excess spoil was constructed to accommodate the initial cuts. The West Pit is a multiple seam operation utilizing truck/shovel and dragline methods, similar to the past East pit operation. Approximately 45 million yd of box cut material was placed in an Rule 2 Permits 2.05-16 Revision Date: 5/25/18 Revision No.: RN -07