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'• <br />INTRODUCTION <br />Vibra-Tech Engineers, Inc. was retained by Pikes Peak Mining <br />Company to monitor ground vibrations produced by .blasting in the <br />Globe Hill and Ironclad pits to develop a distance study with safe <br />vibration limits. The distance study predicts statistically safe <br />stand-off distances for any given charge weight per delay. A test <br />blast in the proposed Cresson pit was then monitored with the <br />intent to compare this data with the distance study. <br />INSTRUMENTATION <br />Vibration records were collected with four GMS-4 blasting <br />seismographs and five Everlert II blasting seismographs. <br />Calibration certificates are on file for all instruments used and <br />all instruments have been calibrated within the past year. <br />The GMS-4 instrument has a frequency response of 2 to 250 Hertz + <br />2dB. This instrument records three orthogonal channels of ground <br />• motion: vertical, longitudinal, and transverse; and it records one' <br />channel of air pressure. All four components were recorded on <br />magnetic tape and were processed by Vibra-Tech Engineers, Inc. in <br />St. Louis, Missouri. The GMS-4 instrument is manually triggered. <br />The Everlert II instrument has a frequency response of 2 to 200 <br />Hertz. This instrument records three orthogonal channels of ground <br />motion: vertical, longitudinal, and transverse; and it records one <br />channel of air pressure. All four components were recorded on disk <br />and the data is processed on-board. The Everlert II is seismically <br />triggered. <br />PROCEDURE <br />Two blasts in the Ironclad pit and three blasts in the Globe Hill <br />pit were monitored at a variety of locations. One blast in the <br />proposed Cresson pit area was then monitored. Please see Appendix <br />I for blast photographs of Shots 2, 4, 5 and 6; and please see <br />Appendix II for maps showing blast and recording locations. <br />Ground vibrations were measured at distances varying from 195 to <br />2889 feet from production blasts. Scaled distances varied from <br />7.51 to 83.98. Linear regression was performed on the data sets to <br />determine +95% confidence intervals as per regulatory guidelines. <br />• <br />2 <br />