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Review of Blasting Operations at Denver Brick Company's Golden Mine <br /> Note that differences for individual blasts will vary depending on their unique frequency intensity <br /> spectrums. Since full range recording of blast induced noise can only be done with linear scale <br /> instruments, it is imperative that all compliance specifications be expressed in linear scale <br /> (dBL). <br /> 10 , 130 <br /> 0 <br /> m -10 C 120 S.te3 L.— <br /> e •30 110 <br /> 3 -m C A <br /> 40 100 <br /> E -550 <br /> < 6C 90 <br /> 70 <br /> t 10 100 1000 10.000 80 <br /> Frequency INt1 70 <br /> Weighting Scales <br /> 120 S,tc 3,C•weget,,q <br /> 110 <br /> l•nee 33 100 i <br /> J1 90 <br /> s0 <br /> C•wephbnq <br /> )0 <br /> A•wegM«•q 170 S-it I A-wegnt N , <br /> 1 <br /> Tnnr hecl 90 <br /> Time Histories 80 <br /> m <br /> 60 <br /> 0 no 4W 6W 800 1000 <br /> Frequency 1Nt) <br /> After Siskind and Summers,(1974) Fourier Frequency Spectra <br /> Figure 2.5- Effects of Weighted Filtering on Air-overpressure Records <br /> USSM RECOMMENDATION Mom RI 8488' <br /> Lower Frequency Limit of Measuring System Maximum Level <br /> 0.1 Hertz high pass system Fiat Response 134 Peak <br /> 2 Hertz high pass system Flat Response 133 Peak <br /> 6 or 6 Hertz high pass system Flat Response 129 Peak <br /> C-weighted system for events Slow Response 105 Peak <br /> with duration lass than 2.0 sec, <br /> Figure 2.6- USBM Recommended Blasting Air Overpressure Limits <br /> 2.3.2 Air Overpressure Limitations: <br /> The regulatory limit defined by USBM and promulgated by Colorado State Department of Labor <br /> Regulations, for airblast measured with 2-Hz response seismographs is 133 dB-L.As indicated <br /> in figure 2.7, damage to old or poorly glazed windows does not occur until overpressure reaches <br /> 13 <br />