2012-06-20_PERMIT FILE - C2010089A (19)

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church, or community or institutional building outside the permit area except at such structures owned by WFC. Ground Vibration. WFC may use seismograph monitors for homes located within 1000' of the proposed blast location, if additional data collection is needed to help perfect WFC's blast modeling program, or at a resident's request, to record the ground vibrations (in /sec) in the three planes (Longitudinal, Transverse, and Vertical). Where appropriate, these same seismographs will also record the air pressure change (dbL) caused by the blast at the same locations. After each blast, the seismographs are downloaded and the information is printed and analyzed. The information is then used to formulate a new blast scale distance factor as well as to judge the shot as being in /out of compliance. For this permit, WFC will use the Maximum Peak Particle Velocity (PPV) vs. distance table located in Table 2.05.3(6)(a) -1 to judge the ground vibrations for compliance purposes. The maximum allowable air blast limits WFC will use for compliance judgment can also be viewed in Table 2.05.3(6)(a) -1. Fly -Rock. Stemming is loaded into blast -holes prior to detonation to substantially reduce the occurrence of fly rock. The depth of stemming will be designed such that the fly rock, which may result from blasting operations, shall not be cast from the blasting site more than one -half the distance to the nearest dwelling or other occupied structure, and in no case beyond the area of control or beyond the line of property owned or leased by WFC. WFC uses crushed rock for stemming to control vertical displacement of fly rock. The horizontally displaced spoil however, is allowed to move within the previous pit area and into position against the existing spoil pile. Blasting within 500 feet of Pipeline. Under the approved MR -82 for the New Horizon Mine Permit, a segment of the CCC Ditch will be located within 500 feet of blasting activities proposed for the New Horizon North Mine. Rule 4.08.4(7)(b) prohibits blasting activities within 500 feet of a pipeline unless approved by DRMS. WFC requests DRMS that this requirement be waived in the NHN permit. The pipe material is heavy duty polyethylene (HDPE). It has adequately resisted blast vibrations at the New Horizon Mine West Lateral Ditch. Blasting has taken place as close to as 147 feet from the pipeline in the New Horizon Mine without any adverse consequence. The pipe carries only water. Should there be any damage to the pipe due to blasting, it will be promptly repaired. No adverse consequence will take place. The pipeline maintenance is also a requirement under the agreement between WFC and CCC Ditch Company. See Appendix 2.05.3(4) -5. Section 2.05.3(6)(a) Page 7 February 2012