Subchapter G. REQUIREMENTS FOR MONITORING

 (a)  If the scaled distance of a blast is 90 or numerically less at the closest building not owned or leased by the blasting activity permittee or its customer, ground vibration and airblast monitoring shall be conducted. The Department may require the permittee to conduct ground vibration and airblast monitoring at other buildings or structures even if the scaled distance is greater than 90.

 (b)  Blasting activities without monitoring may be considered in compliance with this chapter if at a specified location, on at least five blasts, monitoring has demonstrated that the maximum peak particle velocity at the specified location represents more than a 50% reduction from the limit in the permit and this chapter. Future blasts shall maintain a scaled distance equal to or greater than the scaled distance for the monitored blasts.

 (c)  If monitoring is required, a ground vibration and airblast record of each blast shall be made part of the blast report.

 (d)  If monitoring is performed with instruments that have variable ‘‘trigger levels,’’ the trigger for ground vibration shall be set at a particle velocity of no more than .25 inches per second unless otherwise directed by the Department.

 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.

 (a)  Anyone using a monitoring instrument shall be trained on the proper use of that instrument by a representative of the manufacturer or distributor, or other competent individual. A record of that training is to be maintained and available for review by the Department.

 (b)  Monitoring records, at a minimum, shall contain:

   (1)  A calibration pulse on each of the mutually-perpendicular ground vibration traces. These pulses shall represent the dynamic response of the entire recording system to an internally-generated calibration signal, and shall allow the Department to verify that the seismograph is recording ground vibration to its specific accuracy.

   (2)  The time history of particle velocities for three mutually perpendicular ground vibration traces and one air-overpressure trace, including time base, amplitude scales and peak values for all traces.

   (3)  The results of a field calibration test for each channel.

   (4)  The frequency content of all vibration signals using either single degree of freedom (SDF) response spectrum or half-cycle zero-crossing analysis methods.

   (5)  Frequency versus particle velocity plots as indicated in §  211.151(c), Figure 1 (relating to prevention of damage).

   (6)  The name and signature of the individual taking the recording.

   (7)  The location of the monitoring instrument, date and time of the recording.

   (8)  The last calibration date of the monitoring instrument.

 (c)  If the Department questions the validity of a ground vibration or airblast record, or the interpretation of the record, the Department may require a ground vibration or airblast recording to be analyzed or certified by an independent, qualified consultant who is not related to the blasting activity permittee or its customer. When the Department requires that a recording be analyzed or certified, it shall be performed and included with the blast report within 30 days.

   This section cited in 25 Pa. Code §  211.133 (relating to blast reports).