1. A. When seismographic measurements are required the following shall apply:

   1. (1) A record of each blast shall be kept.

   2. (2) All records including seismographic reports shall be retained at least 4 years and shall be available for inspection and shall contain the following minimum data:

      1. (a) Name of blasting company or blasting contractor;
      2. (b) Location, date, and time of blast;
      3. (c) Name, signature, Social Security number of blasters;
      4. (d) Type of material blasted;
      5. (e) Number of holes, burden, and spacing;
      6. (f) Diameter and depth of holes;
      7. (g) Type of explosives used;
      8. (h) Total amount of explosives used;
      9. (i) Maximum amount of explosives per delay period of 8 milliseconds or greater;
      10. (j) Maximum number of holes per delay period of 8 milliseconds or greater;
      11. (k) Method of firing and type of circuit;
      12. (l) Direction and distance in feet to nearest dwelling house, public building, school, church, commercial, or institutional building not owned or leased by the person conducting the blasting;
      13. (m) Weather conditions (including such factors as wind direction and cloud cover);
      14. (n) Height or length of stemming;
      15. (o) Mats or other protection used;
      16. (p) Type of detonators used and delay periods used;
      17. (q) The exact location of the seismograph, and the distance of the seismograph from the blast;
      18. (r) Seismographic readings;
      19. (s) Name and signature of person operating seismograph;
      20. (t) Name of person and the firm analyzing seismographic record.
   3. (3) All field seismographs shall record the full analog wave form of the three mutually perpendicular components of motion in terms of particle velocity. All seismographs shall be capable of internal dynamic calibration and shall be calibrated according to the manufacturer's recommendations.

2. B. Official Tables. Graph I - Maximum Allowable Particle Velocity, inches per second, and Blast Vibration Frequency, H_z

   Table I Distance Versus Weight of Explosive Method
   Distance to a Building	Weight of Explosive per Delay
   Feet Over Feet Not Over	Pounds
   200 to 220	34
   220 to 240	39
   240 to 250	42
   250 to 260	45
   260 to 280	49
   280 to 300	55
   300 to 325	61
   325 to 350	69
   350 to 375	79
   375 to 400	85
   400 to 450	98
   450 to 500	115
   500 to 550	135
   550 to 600	155
   600 to 650	175
   650 to 700	195
   700 to 750	220
   750 to 800	240
   800 to 850	263
   850 to 900	288
   900 to 950	313
   950 to 1,000	340
   1,000 to 1,100	375
   1,100 to 1,200	435
   1,200 to 1,300	493
   1,300 +	520

   Table 2 Distance Versus Peak Particle Velocity Method
   Distance	Peak Particle Velocity of Any One Component
   Feet Over Feet Not Over	Inches per Second
   0 to 100	2.0
   100 to 200	1.75
   200 to 500	1.5
   500 to 1,000	1.0
   over 1,000	0.75

   

Authority: Environment Article, §§15-803 and 15-813; Natural Resources Article, §10-2A-06(c); Annotated Code of Maryland

Effective date: December 11, 1989 (16:24 Md. R. 2617)

Regulation .23C, E amended effective May 14, 1990 (17:9 Md. R. 1088)

Chapter recodified from COMAR 08.05.10 to COMAR 26.21.01, June 1996

Regulation .03E adopted effective May 14, 2001 (28:9 Md. R. 890)