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Design and Performance of Single‐Well Tracer Tests at the Mobile Site
Author(s) -
Molz Fred J.,
Melville Joel G.,
Güven Oktay,
Crocker Ronald D.,
Matteson Keith T.
Publication year - 1985
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/wr021i010p01497
Subject(s) - tracer , aquifer , sampling (signal processing) , geology , permeability (electromagnetism) , advection , instrumentation (computer programming) , soil science , hydrology (agriculture) , geotechnical engineering , groundwater , engineering , chemistry , electrical engineering , filter (signal processing) , biochemistry , physics , membrane , computer science , nuclear physics , thermodynamics , operating system
Tracer tests are the most reliable field methods for obtaining information describing advection and dispersion in aquifers. This paper describes the design and performance of single‐well tracer tests utilizing multilevel observation wells at a field site near Mobile, Alabama. In a given observation well, a total of 7 sampling zones were isolated using inflatable packers and silicone rubber plugs. All instrumentation was contained within a removable insert that extended from the well bottom to the land surface. Each sampling zone contained an electrical conductivity probe and was connected to the surface with two lengths of vacuum tubing. When combined with peristaltic pumps, the tubing allowed mixing of the sampling zone contents as well as water sample collection. A total of 5 experiments were performed using bromide as a conservative tracer. Results showed that the sampling zones were well isolated and that sampling zone mixing was necessary to achieve results that were independent of probe placement within a given zone. Both electrical conductivity and bromide concentration breakthrough curves indicated the presence of a high horizontal permeability zone in the bottom third of the aquifer, although the concentration data were considered the more accurate and reliable. Permeability values based on tracer travel times from the injection‐recovery well to the multilevel observation well varied by a factor of 4 over the aquifer thickness. Such results are reasonably consistent with permeability trends inferred during thermal energy storage experiments performed previously at the same site.