Blasting Information

Control of Airblast and Ground Vibration for Blasting Operations

The requirements for the control of airblast and ground vibration for blasting operations is applicable to those recorded at the location of private dwellings, public buildings, schools, churches, and community or institutional buildings not owned or leased by the person conducting or contracting for the blasting operation.

Airblast from blasting must be controlled so that the maximum allowable airblast at:

• An inhabited building, resulting from blasting operations, may not exceed 130 decibels peak when measured by an instrument having a flat frequency response, /- 3 decibels, over a range of at least 6 - 200 Hz;
• A building not inhabited, resulting from blasting operations, may not exceed 140 decibels peak when measured by an instrument having a flat frequency response, /- 3 decibels, over a range of at least 6 - 200 Hz.

Note: A property owner may register a complaint with the Office of the Fire Marshal, and if considered necessary, measurements on 3 consecutive blasts, using approved instrumentation, may be ordered near to the structure in question. 

Instrumentation

• A direct velocity recording seismograph capable of recording the continuous wave form of the 3 mutually perpendicular components of motions, in terms of particle velocity, shall be used.
• All field seismographs shall be capable of internal dynamic calibration and shall be calibrated according to the manufacturers' specifications at least once per year.
• All seismographs shall be operated by competent individuals trained in the correct use of seismographs. Seismograph records shall be analyzed and interpreted by an independent third party approved by the Office of the Fire Marshal.
• Each seismograph shall have a frequency response from 2 to 150 hertz or greater, and a velocity range from 0.0 to 2.0 inches per second or greater.

Records

A record of each blast shall be kept. All records, including seismograph reports, shall be retained for at least 3 years, be available for inspection, and include the following items:

• Name of company or contractor
• Location, date, and time of blast
• Name, signature, and Social Security number of blaster in charge
• Type of material blasted
• Number of holes, burden, and spacing
• Diameter and depth of holes
• Type of explosives used
• Total amount of explosives used
• Maximum amount of explosives per delay period of 8 milliseconds or greater
• Method of firing and type of circuit
• Direction and distance in feet to nearest dwelling house, public building, school, church, and commercial or institutional building not owned or leased by the person conducting the blasting
• Weather conditions including such factors as wind direction, etc.
• Height or length of stemming
• If mats or other protection to prevent fly rock were used
• Type of detonators used and delay period used
• Seismograph records including seismograph readings when required containing:
  1. Name and signature of the individual operating the seismograph
  2. Name of the individual analyzing the seismograph records
  3. Seismograph reading
  4. The maximum number of holes per delay period of 8 milliseconds or greater

The person taking the seismograph reading shall accurately indicate the exact location of the seismograph, if used, and shall also show the distance of the seismograph from the blast.