Reports
Geologic and hydrologic factors bearing on subsurface storage of liquid wastes in Maryland
1970, Otton, E.G.
Report of Investigations 14
Abstract
Factors that should be considered in deep-well waste injection include the hydraulic properties of the receiving rocks, the presence of impermeable confining layers above and below those rocks, the relation of waste injection to the presence of usable aquifers and of economic deposits of fuels and minerals, the chemical compatibility of the injected wastes and of the receiving rocks, engineering factors such as the construction and operation of the wells in such a way as to minimize leakage from casing failure and rock fractures along which the wastes could escape, and factors influencing the cost of deep-well injection in comparison to the costs of other methods of waste handling.
The State of Maryland is divided into three major regions and these, in turn, are divided into eight major subregions on the basis of physiography, geology, and hydrology and each is discussed in relation to deep-well injection of wastes.
In the Appalachian Region, there are several porous zones that might accept injected wastes, and there are thick sequences of low-permeability rocks that might function as confining layers. In some places there are fresh-water zones that must be considered and in the eastern part of the Western Maryland subregion, there is extensive faulting that might permit vertical leakage of injected wastes.
In the Piedmont Region the highly metamorphosed and fractured rocks of the Catoctin Mountain belt offer few opportunities for practicable injection of wastes because of the low permeability and generally ineffective confining layers. In the Frederick Valley and Triassic Lowlands, faults, sills, and dikes offer possible routes for vertical leakage of injected wastes. Fracturing, faulting, low permeabilities, and general absence of extensive confining layers would appear to preclude safe waste injection.
In the Coastal Plain Region factors related to waste injection decisions range widely. Most of the aquifers contain fresh water in the Inner Coastal Plain and the number decreases seaward. In the Middle Coastal Plain, there appear to be several saline aquifers below a depth of about 2,000 feet and in the Outer Coastal Plain there area many. Throughout the Coastal Plain Region there are extensive thick confining layers.
