PROJECT PROFILE GEOPHYSICAL CHARACTERIZATION OF ABANDONED CLARION, PA COAL MINE When a leading Western Pennsylvania D’Appolonia obtained 37 DC resistivity development and construction firm spe- profiles at the project site using a multi- cializing in institutional and educational electrode measurement system manu- facilities and the oldest and most re- factured by Iris Instruments of Orleans, spected developer and manager of stu- France. The readings were made using dent housing in the country joined a pole-dipole configuration with up to forces to develop, finance, and con- 24 electrodes separated by a distance of struct new student housing on the cam- either 15 or 30 feet. The total length of pus of Clarion University, they did not geophysical survey was nearly 16,000 expect that their construction activities feet. The data were processed as three- would be impacted by the presence of d i me n s io n al b lo c ks u s in g t h e RES3DINV soft- ware. The geophysical survey proved to be extremely effective Opening to abandoned mine at Clarion, PA. for targeting borings in locations where The overall result of the program was mine workings pos- that the geophysical exploration pro- sibly were present. gram was able to rule out the presence Even more signifi- of mine workings across most of the cantly, the geo- site, thus minimizing the need for sub- physical exploration surface drilling. The construction of the program indicated student housing facilities was com- clearly the areas pleted on the originally projected where mining voids schedule, and the combination of geo- were not present. physical exploration and targeted sub- surface drilling reduced what could The portion of the have been excessive costs to accom- site where mine plish characterization of the site. Field setup of resistivity equipment. abandoned mine workings. Construc- wo r k i n gs we r e tion had already commenced when known to exist was backhoe excavations revealed previ- well defined, and ously unknown mine workings at a the mine layout plan depth ranging from 20 to 50 feet in the suggested that the 5-foot-thick Lower Clarion Coal seam. mine shafts spread out laterally from The problem facing the developer was the known site en- that construction had already started, try, but did not the extent of the mine workings was penetrate deeply unknown, and the site was quite large, into the hill where covering more than 65 acres. If a con- construction was ventional program of subsurface drill- planned. In areas ing to map the mine voids had been away from the area undertaken, construction would not that was known to have been able to proceed on schedule, be mined, geophysi- and the extensive subsurface investiga- cal anomalies were tion would have been very costly. encountered that D’Appolonia and the site exploration borings were subse- contractor worked together to develop a quently able to con- program of geophysical exploration firm were not re- combined with borehole drilling to lated to the aban- Results of 3-D analysis depicting the resistivity at the level of the identify the extent of the abandoned doned mine work- flooded mine workings in the lower Clarion Coal. mine workings. ings.
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