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<br />v 1 V. r` , C~n 4955 Miller Sveet, Suite 201, Wheat Ridge, CO 80033 <br />The Vibration Monitoring F.xperls 303-940-8884 FAx 303-940-8885 <br />ENVIRONMENTAL AFFAIRS <br />• <br />~J <br />Mr. Brian Dunfee <br />Senior Manager <br />Environmental Engineering <br />Peabody Coal Company <br />1300 South Yale <br />Flagstaff, AZ 80601 <br />Dear Mr. Dunfee, <br />vibrations caused by blasting. <br />Vibra-Tech Engineers, Inc. has sold seismographs and processed <br />blast record data for Peabody Coal Company's Seneca Mine near <br />Hayden, Colorado since 1990. Blast records for blasting in the 2W <br />area of the Seneca Mine and specifically monitoring of the oil well <br />owned by Meridian Oil Company, Colorado permit # 48361 located in <br />the NE, NW Sec. 22, T5N, R88W, Routt County, Colorado indicate <br />ground vibration has never been in excess of 4.0 inches per second. <br />Thirty-eight blast records have been analyzed, the majority of the <br />peak particle velocities have been less than 1.0 inch per second. <br />Two records were in excess of 2.0 inches per second, the latest on <br />3/27/92. The well has not been adversely effected by the ground <br />October 19, 1993 <br />OCT 2 01993 <br />WESTERN DIVISION <br />pEABODY COAL COMPANY <br />Engineered structures such as oil wells, steel tanks, pipelines and <br />steel frame buildings are not damaged by ground vibrations of less <br />than 5.0 inches per second. The office of Surface Mining and <br />United States Bureau of Mines blast vibration regulations are <br />intended to protect residential houses and other relatively fragile <br />structures. Below is an excerpt from "Explosives and Rock <br />Blasting" by Atlas Powder Company; <br />Type of Structure <br />Type of Damage <br />Particle Velocity at <br />Which Damage Starts <br />Houses <br />Concrete Blocks <br />Cased Drill Holes <br />Mechanical Equipment <br />Prefabricated Metal <br />Building on Pad <br />Plaster Cracking <br />Cracks in Blocks <br />Horizontal Offset <br />Shafts Misaligned <br />Twisted Metal, <br />Cracked Pad <br />2.0 inches/second <br />8.0 inches/second <br />15.0 inches/second <br />40.0 inches/second <br />60.0 inches/second <br />