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• coal will also be blasted, the overburden bleating will generate <br />greater ground vibrations and is therefore used for the analysis. <br />The Geosonics Inc. report, included at the end of this section, <br />demonstrates that a particle velocity of 9.0 inches per second is <br />allowable at the pipeline, based on a 2.0 safety factor. <br />In addition to the Geosonics Inc. evaluation, two additional <br />sources are cited to substantiate the capability of the pipeline <br />to withstand high particle velocities. <br />The first is a paper by Charles Dowding, Janice Means and Dennis <br />Clark presented at the American Society of Civil Engineers <br />convention in Boston in 1986 and subsequently published in Rock <br />Mechanics and Rock Engineering magazine in 1987. The paper was <br />titled Case Histories of Close-in Blast Eacitation of Pivelines <br />and a Sox Culvert. The paper describes how buried gas <br />transmission lines and buried waterlines can withstand large <br />particle velocities because strains in such restrained structures <br />are limited to the strains of the ground surrounding the <br />structure, unlike surface structures which respond freely to the <br />ground vibration. Cases were presented where close-in blasting <br />was conducted near a buried, welded steel gas transmission line <br />similar to that at the Rimrock Mine. Single confined shots were <br />• fired which resulted in particle velocities at the line of 6.6 <br />inches per second and strains of 38 microinches per inch. Ho <br />damage of any kind was noticed in the pipeline. Similar tests <br />performed on a buried waterline resulted in particle velocities <br />of 8.3 inches per second and strains of 111 microinches per inch <br />without any damage to the line. Distances between the lines and <br />the shots were from 17 to 40 feet in all cases. <br />The second is a report published in 1978 by the American Gas <br />Association titled Analysis and Testing of Pive Resaonse to <br />Buried Explosive Detonation, Report L51378 by Westine, Esparza <br />and Wenzel. In this report, a series of worst case experiments <br />were conducted for the American Gas Association involving <br />confined blasts at short distances (<15 feet) from buried gas <br />transmission lines. All tests showed the line's ability to <br />withstand particle velocities above 10.0 inches per second. One <br />of the blasts involved the detonation of 15 pounds of ANFO at a <br />distance of 13 feet from the pipe. The blast induced a peak <br />radial particle velocity of 45 inches per second and maaimum <br />circumferential and tensile longitudinal strains of S37µ and 786µ <br />• 3 <br />