Hydraulic Pulse Interference Test
The hydraulic pulse interference test was initially developed for characterizing petroleum reservoir permeability and hydraulic connection between production wells. GeoSierra Environmental has modified and enhanced the equipment and method for use in characterizing shallow groundwater sites and to act as a quality assurance technology for iron PRBs. The first commercial application of the hydraulic pulse interference test was for its first iron PRB installation in 1997. Since that time, the equipment, procedures and interpretation software have been utilized by GeoSierra Environmental at most of the iron PRB installations for both site characterization and quality assurance testing to ensure the constructed iron PRB does not impede groundwater flow. Additional applications where the HPIT has been used include integrity verification of slurry walls and design of extraction well systems.
The hydraulic conductivity of the PRB is quantified by the hydraulic pulse interference tests, with pulse source wells on one side of the wall and high precision receiver transducers installed in wells on the opposite side. Pulse interference testing involves a cyclic injection of clean water into the source well and high precision measurement of the pressure pulse in a neighboring well.
The time delay and attenuation of the hydraulic pulse enables various hydrogeologic parameters, such as hydraulic conductivity and storativity, to be evaluated. These parameters, measured both pre and post reactive barrier installation, confirm that the reactive barrier has no negative effect on local groundwater flow regimes. The pulse interference test is also ideal for the hydraulic characterization of complex flow systems, such as fractured bedrock, braided stream and esker deposits. Because the transient hydraulic flow characteristics can be determined, the hydraulic flow regimes can be clearly delineated with a high degree of precision.