MM&A has a wealth of experience in evaluating the interactions between both underground and surface mining and the hydrogeologic regime. Understanding the hydrogeologic framework not only provides the basis for assessment of probable hydrogeologic consequences of mining, but also allows anticipation of mining conditions. MM&A hydrogeologists investigate the stratigraphic, structural, and geotechnical controls influencing the subsurface hydrogeologic system to determine the nature and degree of interaction between that system and mining. Applications of these investigations have included: pre-mining assessment of hydrogeologic impact for permitting and hydrogeologic reclamation planning purposes; assessment of probable mining conditions beneath stream valleys, and impact of mining upon the stream; post-mining evaluation of stream-crossing impacts; assessment of impact to domestic water supplies; evaluation of conditions to be encountered in shaft and slope construction; and remediation of drainage impacts from flooded underground workings and/or surface disturbed areas.
Hydrogeologic evaluation begins with a detailed geologic evaluation of the subsurface from cores and geophysical logs to identify fractures, evidence of weathering, and aquifer or aquitard potential of the various strata. MM&A maintains comprehensive geophysical logging capabilities, including acoustic televiewer, borehole video camera, and fluid conductivity/temperature probes to assist in hydrogeologic investigations. Hydrogeologically important strata are delineated in maps and cross-sections, and structural influences are identified. Photolineament analysis is employed to identify potential fracture traces that may enhance hydrogeologic interactions within your mine.
Subsurface hydrogeologic conditions are assessed using monitoring wells and piezometers to confirm groundwater flow paths, horizontal and vertical gradients, and degree of intercommunication between horizons. We are experienced in successful dye tracer applications in complex hydrogeologic settings, and with strict protocols to eliminate potential false position indicators. Aquifer conductivity is evaluated by means of in-situ pressure tests (“packer tests”), aquifer pumping tests, and slug tests. From these data, flow nets and hydrogeologic models are constructed to define the hydrogeologic regime, and the effects of mining upon the regime are evaluated.