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MINIMUM DISTAN!ES BETWEEN <br /> QUARRY AND LANDFILL TO <br /> PREVENT FRACTURING OF <br /> UNDERLYING ROCK <br /> Results of two carefully conducted experiments can be <br /> summarized to answer the question : "What blast vibration level will <br /> increase fracture size ( and thus hydraulic conductivity) of the rock <br /> mass surrounding a quarry? " . One experiment deals with previously <br /> fractured rock and the other with unfractured rock . Both were <br /> conducted under field conditions . The first series of experiments is <br /> reported in a "Survey of Blasting Effects on Ground Water Supplies in <br /> Appalachia "and measured changes in the specific capacity of wells <br /> which is proportional to conductivity . The second series is reported <br /> in "Blast Produced Fractures in Lithonia Granite" and involved <br /> measurement of distances to which fractures can be produced in <br /> unfractured rock . <br /> Both of these experiments report or infer blast initiated <br /> fracturing in rock masses . These fractures are not craters , caverns , <br /> or large voids . They are more like the small fractures that appear in <br /> the mortar in brick or concrete block homes . Thus these cracks or <br /> fractures are similar to the fractures that already exist in the rock <br /> and will not radically alter the behavior of the rock mass . The <br /> criteria deduced from these two studies are conservative in their very <br /> nature because they dealt with the threshold of change in the behavior <br /> of rock masses . <br />