§ 211.172. Monitoring instruments.

 If monitoring is required, the monitoring instrument shall provide a permanent record of each blast.

   (1)  A monitoring instrument for recording ground vibration, at a minimum, shall have:

     (i)   A frequency range of 2 Hz to 100 Hz.

     (ii)   Particle velocity range of .02 to 4.0 inches (5.08 x 10^-4 to 0.10 meters) per second or greater.

     (iii)   An internal dynamic calibration system.

   (2)  A monitoring instrument used to record airblast shall have:

     (i)   A lower frequency limit of 0.1, 2.0 or 6.0 Hz.

     (ii)   An upper end flat-frequency response of at least 200 Hz.

     (iii)   A dynamic range that, at a minimum, extends from 106 to 142 dBL.

   (3)  A monitoring instrument shall be calibrated annually and when an instrument is repaired and the repair may effect the response of the instrument. Calibration shall be done by the manufacturer of the equipment, or by an organization approved by the manufacturer, or by an organization having verifiable knowledge of the calibration procedures developed by the manufacturer. The calibration procedure shall include testing the response of the entire system to externally-generated dynamic inputs. These inputs shall test the entire monitoring system at a sufficient number of discrete frequency intervals to assure flat response throughout the frequency ranges specified by this chapter. Dynamic reference standards used for calibration shall be traceable to the National Institute of Standards and Technology (NIST). Calibration procedures and documentation of calibration shall be made available for review by the Department.

   (4)  A nonalterable sticker that is clearly visible shall be firmly affixed to the instrument. The sticker shall indicate the name of the calibration facility, the calibration technician, the date of calibration and frequency range of the airblast monitor.