Pulse Testing

The hydraulic pulse interference test was initially developed for characterizing petroleum reservoir permeability and hydraulic connection between production wells. GeoSierra has modified and enhanced the equipment and method for use in characterizing shallow groundwater sites and to act as a quality assurance technology for both iron PRB and slurry wall constructed systems. The first commercial application of the hydraulic pulse interference test was by GeoSierra at its first iron PRB installation at the Caldwell Superfund site in Fairfield, NJ in 1997. Since that time the hydraulic pulse interference testing equipment, procedures and interpretation software have been utilized by GeoSierra at all of the iron PRB installations for both site characterization and quality assurance testing to ensure the constructed iron PRB does not impede groundwater flow.

The hydraulic continuity of the PRB is quantified by 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. The test involves a cyclic injection of fluid 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 the hydraulic effectiveness and continuity of the wall to be assessed. See: PRB pulse testing.

GeoSierra’s pulse interference testing method is also ideal for the hydraulic characterization of complex flow systems, such as fractured bedrock, braided stream and esker deposits. Being a transient hydraulic test, transmissivity and storativity can be determined, and hydraulic flow regimes can be clearly delineated, as well as characterize complex directional permeability of fractured bedrock. See: Characterization pulse testing.

GeoSierra’s 3^rd generation hydraulic pulse interference receiver pressure gage consists of a high precision (1/10,000psi) differential wet/wet temperature compensated gold plated strain gage device.  The gage is amplified and compensated with micro-circuitry to provide a 4-20mA current amplitude over its full range. The microcircuit is encapsulated in a high density resin for use in hostile groundwater environments at depth.

All of GeoSierra’s pulse receiver strings contain the new 3rd generation gage.  The gage has been used operationally in pulse interference tests at numerous sites for a number of years without loss of functionality or precision.

The hydraulic pulse interference test is ideal to hydraulically characterize fractured bedrock systems, to determine explicitly the directional hydraulic connectivity and transmissivity of the fracture network.  Recent pulse tests on fractured dolomitic bedrock show the rapid response in uncased monitoring wells some 500’ apart with minimal injection of fluid during the test. The hydraulic connectivity of the fractured network at this site was quantified by numerous pulse test directional arrays between 11 wells.  The transmissivity of the fracture network was determined directly from type curves generated specifically for the fractured system.

Third Generation Receiver Gage