Performance and evaluation of pumping tests in karstic carbonate and evaporite aquifers

During the last four decades P. E. LaMoreaux & Associates performed several pumping tests in karstic terrains, including limestones, dolomites, and evaporates (gypsum/anhydrite, halite). Similarities and differences and/or variations in the size and shape of the cone of depressions formed by pumping in different karst settings are presented. A wastewater storage lagoon failed due to development of a sinkhole at a site in the Lehigh River valley, Allentown, Pennsylvania. Five saturated zones were identified within the bedrock based on the analysis of cores and interpretation of geophysical logs. An aquifer test was performed to determine hydraulic characteristics (transmissivity, hydraulic conductivity, and storativity) of the karstified carbonate aquifer. The shape of the cone of depression was controlled by the geologic structure of the area and the discharge rate during the test. Naturally occurring springs and seeps contribute a daily average of 3,300 metric tones of chloride to the Red River, Childress, Texas, through its tributaries. A drilling program was carried out to understand and delineate interconnection of subsurface fracture system and cavities in carbonate aquifers. A pumping test was performed to determine the number and location of wells, and pumping rates to control the brine discharge from the area. Transmissivity of the carbonate/evaporate bedrock aquifer system ranges from 149 m(2)/d to 5,840 m(2)/d, with an average of 2,108 m(2)/d. The high value of transmissivity is indicative of the karst nature of the bedrock aquifer system. Engineering and constructing a secure hazardous waste landfill in a limestone terrain in New York State (Niagara River corridor) required a geological, structural and hydrogeological investigation. A pumping test was performed to determine the isotropy/anisotropy of the aquifer, the vertical and lateral extent of the interconnected fracture system, and the existence or absence of any geologic and hydrogeologic boundaries. Comparison of the three sites demonstrates wide variations as expected in hydraulic characteristics of aquifer system. The cones of depressions show anisotropy, and are oriented in a particular direction. Their size, shape, orientation depends on development of fractures system in karst settings, which are being tested. Typical orientations of cone(s) of depression in karst carbonate rocks correspond to water-filled primary conduits acting as preferred flow paths.