Premium
Complex Aquifer‐Aquitard Relationships at an Appalachian Plateau Site
Author(s) -
Peffer Jeffrey R.
Publication year - 1991
Publication title -
groundwater
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.84
H-Index - 94
eISSN - 1745-6584
pISSN - 0017-467X
DOI - 10.1111/j.1745-6584.1991.tb00512.x
Subject(s) - aquifer , geology , oil shale , borehole , plateau (mathematics) , hydraulic conductivity , groundwater , geomorphology , geochemistry , petrology , soil science , geotechnical engineering , paleontology , soil water , mathematical analysis , mathematics
Initial test data from a fractured, shale‐dominated sequence at a proposed landfill site in the Appalachian Plateau exhibited an apparent inconsistency: the unit performed in some ways as an aquitard; yet it was capable of high well yields which suggested it was an aquifer. High head drops (tens of feet) and dramatic ground‐water quality differences (hundreds of ppm for sulfate) occurred across the shale indicating that it is an aquitard. However, the shale sequence supported yields up to 60 gpm in test wells and one production well. This inconsistency suggested high anisotropy in vertical versus horizontal hydraulic conductivity. A second detailed stage of testing confirmed the coincidence of some yielding zones to more brittle interbeds and bedding fractures within the shale sequence. An approach involving several different techniques, including analysis of hydrographs, vertical gradients, ground‐water quality differences, borehole geophysical logs, and pumping tests, was found to be effective in aquifer‐aquitard delineation at this site. The study showed that in waste disposal investigations in the Appalachian Plateau, it is inappropriate to use well yield alone to identify aquitards as these may be complex with numerous interlayered aquifers.