7 Colo. Code Regs. § 1101-9-6-10
Current through Register Vol. 47, No. 20, October 25, 2024
Section 7 CCR 1101-9-6-10 - Blasting Vibration and Air Over-Pressure Standards(A) In all blasting operations, blasters shall use one of the following methods to monitor or control the intensity of motion in the ground at the nearest dwelling, house, school, church, commercial or occupied building. These limits do not apply to property owned, leased or contracted by the blaster's company or property on which the owner provides a voluntary written waiver from these restrictions. (1) Option 1 - Frequency Versus Particle Velocity graph. A blasting operation shall have the option to use the graph shown in Figure 6-10 to limit peak particle velocity based upon the frequency of the blast vibration. Allowable vibrations fall below the limits indicated by the central lines; non-allowable vibrationsNon-Allowable Vibrations lie above the lines. Seismographs shall meet the following requirements: (i) Monitoring instruments shall have a flat frequency response between 2 and 250Hz for particle velocity.(ii) The digitizing sampling rate for peak particle measurements shall be at least 1,024 samples per second.(iii) Seismographs shall be capable of performing a self-test of velocity transducers and printed event records shall indicate whether or not the sensor test was successful.(iv) Monitoring instruments shall be capable of recording particle velocities with intensities ranging from 0.02 to 5.0 inches per second.(v) Monitoring systems shall be calibrated by a service center approved by the manufacturer within at least two years of the time of use. Certificates documenting date of calibration, issued by the approved service center, shall be kept by the user.(vi) Monitoring systems shall be capable of printing hard-copy reports showing the date and time of monitoring, the maximum peak particle velocity (PPV) measurements, and plotted PPV-time waveform plots.(vii) For all blasts with a scaled distance less than 100 ft/lb0.5, seismographs monitoring motion shall be set to trigger at a level of 0.05 in/s. The following equation shall be applied when calculating the scaled distance.
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Where: Ds = Scaled distance (ft/lb0.5)
D = Distance to the nearest structure (ft)
W = Maximum weight of explosive detonated within any 8 millisecond window (lb)
(viii) Vibration analysis results must be presented in comparison with the RI 8507, adopted by United States Bureau of Mines (USBM) and as shown in Figure 6-10.(ix) If a valid vibration record showing compliance with the MAPV limits shown in figure 6-10 is not available for inspection, the maximum charge weight per delay (W) must conform to the scaled distance limitations as prescribed in Option 2. FIGURE 6-10
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Table: U.S. Bureau of Mines RI 8507, 2009
(2) Option 2 Scaled Distance - when seismic monitoring is not performed, the maximum weight of the explosive detonating within any 8-millisecond time period shall not exceed the amount allowed by a calculation using the scaled distance factors given in Scaled Distance column of Table 6-10. The following equation shall be applied when utilizing the scaled distance calculations to control blast-induced vibration.
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Where: Ds = Scaled distance (ft/lb0.5)
D = Distance to the nearest structure (ft)
W = Weight of explosive detonated within any 8 millisecond window (lb)
Example Maximum Charge Weight per Delay (W) Calculation:
Given: Ds = 55 (ft/lb0.5)
D = 500 ft. therefore W = (500 / 55)2 = 82.6 lb
Table 6-10 | Blasting Vibration and Air Over-Pressure Standards |
Distance From Blast (Ft) | Option 2 Scaled Distance Factor Units Are Ft/Lb0.5 |
0 to 300 | 50 |
301 to 5000 | 55 |
5001 and Greater | 65 |
(B) Air over-pressure (air blast) limitation: Air over-pressure at the nearest dwelling house, school, church, or otherwise occupied buildings shall not exceed 133 dB (0.0129 psi). Measuring air overpressure is not required for all blasting operations. However, due to complaints or other circumstances, the Division may require blasters to monitor air over-pressure. All instruments used to measure air over-pressure compliance shall:(1) Employ linear microphones with a flat frequency response between 2 and 200 Hz(2) Have a digital sampling rate of at least 1024 samples per second; and(3) Be capable of measuring air over-pressure from 120 to 140 dB-Linear (0.0029 to 0.029 psi).38 CR 03, February 10, 2015, effective 3/10/201541 CR 21, November 10, 2018, effective 12/1/201842 CR 06, March 25, 2019, effective 5/1/2019