DEEP-BOREHOLE DISPOSAL POTENTIAL AND THE SOUTHEASTERN UNITED STATES’ GEOLOGY

The southeastern United States, defined here as the geographic area of the states of Alabama, Georgia, Florida, Mississippi, and South Carolina comprises a relatively stable geological area of the North American craton, with minimal local exceptions to geological stability, which is a significant consideration for deep-borehole waste storage or disposal operations. Regarding key points in the set of recent deep-borehole siting criteria to be described below, there are significant areas of the southeastern United States with bedrock of various lithic types likely acceptable for waste storage and disposal at relatively shallow depths, which also (1) are not near any shear zones, stress fields, or tectonic features, (2) are lacking in seismicity (exceptions are the Charleston, South Carolina earthquake zone and areas adjacent to the New Madrid, Missouri earthquake zone), (3) are devoid of relatively recent (Quaternary) volcanism and fault activity and very low in geothermal activity, (4) have relatively shallow aquifers and aquifer systems that can be avoided by choosing appropriate disposal locations, (5) and are at suitable distance from human development, petroleum drilling activity, and existing sites of and sources for human-produced radioactive contamination. The southeastern U.S. encompasses key rock types (including crystalline rocks, shale formations, and rock salt bodies) within the context of extant geological terrains (i.e., coastal plain region, folded mountain belts (valley and ridge), Piedmont and Blue Ridge areas, and highland plateaus. The largest geological terrain of the southeastern United States, the coastal plain, is geologically diverse mainly because of the laterally varying character within underlying basement rocks and its basement rock structures. Even so, in some areas, the coastal plain and its underlying crystalline basement rocks are generally well-suited to hosting potential deep-borehole storage or disposal operations.