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The resulting analysis is used to determine distance and charge weight relationships required <br />for ground motion regulatory compliance. This study was designed to be conservative in <br />nature. The intent was to maximize the ground motion produced by the test shots. <br />Typically in mine production blasting, explosive energy is consumed by fragmentation and <br />displacement of the rock mass. The confined test blasts minimized fragmentation and <br />displacement while maximizing ground motion. <br />INSTRUMENTATION <br />Vibration records were collected using eleven blasting seismographs: three Blastmate [ll <br />models, and eight MiniMate Plus models. The seismographs record particle velocity <br />digitally in the frequency range of I.5 to 250 Hertz. Each shot is measured in three <br />orthogonal channels of ground motion: vertical, longitudinal, and transverse. Zero- <br />crossings of each of the three-waveform components are calculated to determine frequency <br />response. The instruments aze seismically triggered and record each channel digitally at the <br />rate of 1024 samples per second. Each vibration recording is printed on a single page with <br />date, time, trigger source, trigger level, range, record time length, instrument serial number, <br />battery level, calibration date, and file name in the title block. <br />An independent parry using a shake table and electronics traceable to the National Bureau of <br />• Standards calibrates all instruments annually. Copies of calibration certificates are found in <br />Appendix II. In addition, each instrument performs aself--test after each recorded event. <br />This is a check of the geophone's overawing and dampening. Attached as Appendix III, is <br />an excerpt from the Blastmate 111 User's Manual describing the specifications and function <br />of the instrumentation and record processing. <br />PROCEDURE <br />Four, six inch diameter holes were drilled to a depth of 40 feet at the test site. Each hole was <br />loaded with 100 pounds of ANFO initiated by a cast booster, with approximately 34 feet of <br />stemming (drill hole cuttings). Each shot was detonated individually. The charge weight <br />was selected to maximize the ground motion created by each detonation, while eliminating <br />energy loss due to creation of fly-rock and permanent ground displacement. This method is <br />inherently conservative, as comparison of production blasting to previous studies has <br />demonstrated. <br />Seismographs were placed at distances tom 102 feet to 789 feet away from the test shots <br />(see map in Appendix I) and were set up in an approximate line betty-een the test shots and <br />the nearest structures in Cripple Creek. Care was taken to ensure good geophone coupling <br />with the ground. Snow and the top frozen soil layer were removed and spikes were used on <br />• <br />3 <br />