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• Blasts will have no more than 72 holes. <br />• Holes will be drilled to depths ranging from 30 to 60 feet. <br />• The maximum weight of explosives per hole will be 7401bs. <br />• The maximum weight of explosives per blast will be 54,7201bs. <br />• Holes will be drilled with a 7-7/8 drill bit. <br />• Holes will be drilled on a 16' X 18' pattern. <br />• Explosive material will be placed in the holes no closer than 10 feet from the surface. <br />• The remaining upper portions of the holes will be filled with drill cuttings. <br />• Blast initiation will occur using anon-electric system. <br />• Delays along rows will be 9 milliseconds (ms) each. <br />• Delays between rows will be 100 milliseconds (ms) each. <br />• Delays downhole will be 600 milliseconds (ms} each. <br />• Blast hole detonation will be sequential, rather than simultaneous. <br />How LCC adhered to these requirements for the six LCC blasts that aze the subject of this review is <br />discussed in the next sections of this report. <br />B. Evaluations <br />I obtained copies of LCC's blast logs for two blasts that occurred on 5/16/02, one blast that <br />occurred on 5/20!02, and three blasts that occurred on 5!23/02. Mr. Frank Smith, who is an <br />employee with Buckley Powder Company (the contract blasting company for LCC), additionally <br />faxed me some information on 5/29/02 pertaining to the seismograph that he uses to monitor the <br />ground vibration and airblast levels generated by LCC's blasts. Mr. Smith also faxed me some <br />information on 6/4/02 pertaining to the locations of the seismograph and Lhe blasts. <br />Mr. Leef's 5/23/02 request for inspection referenced a blast ocurring on 5/21/02. Mr. Smith <br />informed me during a telephone conversation on 6f4/02 that a blast did not occur on S/21f02. I <br />telephoned Mr. Leef on 6/4/02, and asked him about the 5/21/02 date of the blast that he had <br />referenced. Mr. Leef indicated that he couldn't remember the exact date of the blast, but that he <br />was sure it was either S/20/G2 or 5/21/02. I have therefore assumed the blast Mr. Leef referenced <br />specifically in his request occurred on 5/20/02. <br />Rule 4.08.4(10) of the Regulations of the Colorado Mined Land Reclamation Bcazd for Coal <br />Mining describes the amount of ground vibration resulting from blasting that is allowed to occur at <br />certain protected structures situated beyond a mine's permit area. These ground vibration limits are <br />based upon distances between those structures and the blasting site. For protected structures <br />situated within 300 feet of a blast site, the maximum peak particle velocity (PPV) allowed at those <br />structures by Rule 4.08.4(10) is 1.25 inches per second (ips). For protected structures situated 301 <br />feet to 5000 feet from a blast site, the maximum allowable PPV is 1.00 ips. For protected structures <br />situated 5001 feet and further from a blast site, the maximum allowable PPV is 0.75 ips. <br />Rule 4.08.4(10)(c)(i) describes the mathematical formula that describes the maximum weight of <br />explosives that maybe detonated within any 8-ms interval within a blast pattern, based upon <br />