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criteria have been taken into consideration: <br />a. Examining the highwall for geologic rock formation thickness and rock type. <br />b. Consult with the blast -hole drill operator for hardness of the rock and thickness within <br />the proposed blast area. <br />c. Consult with the overburden shovel operator for size of blasted rock and ease of <br />digging. <br />d. Location of shot in relationship to dwellings and other structures. <br />e. Reviewing previous seismic blast records for peak particle velocity. Peak particle <br />velocities for each shot will be closely monitored by seismic recorders and will be kept <br />below the 1 in /sec limit at any inhabited structure off the mine property. WFC will <br />make every attempt to keep the PPV as low as practical while still getting the <br />overburden fractured to our satisfaction. <br />Production patterns will vary in burden and spacing dimensions. Burden spacing will range from <br />10 to 15 plus feet. Spacing will vary from 15 to 20 plus feet. Burden and spacing dimensions <br />are governed on drill bit size (5.25 to 7 inch diameter), hardness of rock and degree of <br />fragmentation desired. Normal production blasting will be a rectangular pattern with on- echelon <br />delays. Staggered patterns have been used in the past with success and will be used in the <br />future as conditions warrant. Stemming will most generally be washed gravel to contain the <br />pressures and reduce fly rock. Typically, six to eleven holes per row and six to twenty rows per <br />shot will be used. Smaller or larger patterns may be used or tried to make the shot more <br />economical or to provide better overburden fragmentation. <br />Standard on- echelon delay sequencing in normal production shots will use appropriate delays in <br />order not to exceed the peak particle velocity as described in Table 2.05.3(6)(a) -1. The <br />maximum peak particle velocity in blasting operations at NHN shall not exceed the limits in <br />Table 2.05.3(6)(a) -1 at the location of any dwelling, public building, school, church, or <br />community structure or institutional building, outside of the permit area. WFC may vary from this <br />design somewhat to reduce ground vibrations and increase fragmentation. <br />SECTION 2.05.3(6)(a) PAGE - 6 - JULY 2013 <br />7TR -OZ <br />"'�pprvved <br />/I I. "U/ -10/3 <br />