Abstract. Bacteriophages are increasingly used as tracers for quantitative analysis in both hydrology and hydrogeology. The biological particles are neither toxic nor pathogenic for other living organisms as they penetrate only a specific bacterial host. They have many advantages over classical fluorescent tracers and offer the additional possibility of multi-point injection for tracer tests. Several years of research make them suitable for quantitative transport analysis and flow boundary delineation in both surface and ground waters, including karst, fractured and porous media aquifers. This article presents the effective application of bacteriophages based on their use in differing Swiss hydrological environments and compares their behaviour to conventional coloured dye or salt-type tracers. In surface water and karst aquifers, bacteriophages travel at about the same speed as the typically referenced fluorescent tracers (uranine, sulphurhodamine G extra). In aquifers of interstitial porosity, however, they appear to migrate more rapidly than fluorescent tracers, albeit with a significant reduction in their numbers within the porous media. This faster travel time implies that a modified rationale is needed for defining some ground water protection area boundaries. Further developments of other bacteriophages and their documentation as tracer methods should result in an accurate and efficient tracer tool that will be a proven alternative to conventional fluorescent dyes.
There has been increased interest in low transmissivity formations as barriers to, and hosts for, different hazardous waste. Long periods of time are generally required to measure their in situ pressures or hydraulic heads. Sites need extensive instrumentation and monitoring schemes, which may be costly and may require long periods of time prior to providing well documented site‐specific data. A method has been developed that allows pressure and head distribution to be determined based on limited formation testing. This distribution can then be used to refine the final design of the borehole monitoring instrumentation.
Recent work on shallow and deep, hazardous and nuclear waste disposal studies in Canada and Europe has provided the opportunity to investigate different methods for extrapolating and estimating the distribution of pressure and equivalent hydraulic head of the pore water in tight formations. The result is an approach that is cost‐effective, technically reasonable and relatively rapid. The technical basis of the method is not new. However, its application to determining profiles of either formation pressure or hydraulic head has not been well documented. This approach has potential for use in many site investigation studies.
The method determines the profile of head or pressure between two “input” layers or formations, which have been well characterized with respect to their pressures or hydraulic heads and associated fluid characteristics. The pressure profile between the two layers is a function principally of the transmissivity of the tight formations between the input layers. Therefore, the primary objective of testing of the zones between the two input layers is designed to quantify this parameter. This testing can be relatively rapid compared to the time required to measure a representative formation pressure or water level. The technique is computerized for efficient tabulation and graphical data display. This paper presents the rationale associated with the extrapolation technique. Examples are given where the technique has been applied to both soil and rock formations with transmissivities less than 10‐8 m2/s and at depths up to 2,000m.
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