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Title: Measuring the vertical permeability of horizontally- stratified sedimentary rocks

The vertical permeability of horizontally stratified rocks is usually assumed to be significantly less than the permeability of horizontal structural features such as bedding plane partings and sheeting structure. Consequently it is also assumed that this type of media provides suitable vertical barriers to the migration of both aqueous and non-aqueous phase groundwater contaminants. To investigate this assumption, a site adjacent to an inactive dolostone quarry was instrumented using nine boreholes drilled to a depth of approximately 25 m in a 30 x 30 m area. The area is immediately underlain by flat-lying thick-bedded dolostones of Middle-Silurian age. Six of the boreholes were drilled at angle of 45[degree] to intersect two vertical fracture sets oriented at 020[degree] and 110[degree] which were identified by mapping the fractures in the quarry. Detailed hydraulic tests (constant-head method) were conducted in each of the boreholes using a packer spacing of 0.5 m to determine the hydraulic properties of the individual horizontal and vertical fractures and fracture zones. In addition, four pumping tests were conducted in which a fracture zone in one of the vertical boreholes was shut-in and pumped and the hydraulic response was monitored in the observation boreholes using pressure transducer installed inmore » 15 intervals isolated with multiple-packer strings. The results of the constant-head tests show that although the groundwater flow system in the dolostone is dominated by 3--4 horizontal fracture zones, the average permeability of the vertical fractures is only one order of magnitude less than the average permeability of the horizontal fractures. However, this aspect of the flow system is not detected using pumping tests, the results of which suggest that the average permeability is 3--4 orders of magnitude less in the vertical direction.« less
Authors:
;  [1] ;  [2]
  1. (National Water Research Inst., Burlington, Ontario (Canada))
  2. (Woodward-Clyde Inc., Wayne, NJ (United States))
Publication Date:
OSTI Identifier:
5578718
Report Number(s):
CONF-9303211--
Journal ID: ISSN 0016-7592; CODEN: GAAPBC
Resource Type:
Conference
Resource Relation:
Journal Name: Geological Society of America, Abstracts with Programs; (United States); Journal Volume: 25:2; Conference: 28. annual Geological Society of America (GSA) Northeastern Section meeting, Burlington, VT (United States), 22-24 Mar 1993
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; 54 ENVIRONMENTAL SCIENCES; GROUND WATER; FLOW MODELS; SEDIMENTARY ROCKS; PERMEABILITY; CARBONATE ROCKS; ENVIRONMENTAL TRANSPORT; EXPERIMENTAL DATA; FIELD TESTS; GEOLOGIC FRACTURES; HYDRAULIC CONDUCTIVITY; HYDROLOGY; STRATIGRAPHY; DATA; GEOLOGIC STRUCTURES; GEOLOGY; HYDROGEN COMPOUNDS; INFORMATION; MASS TRANSFER; MATHEMATICAL MODELS; NUMERICAL DATA; OXYGEN COMPOUNDS; ROCKS; TESTING; WATER 580000* -- Geosciences; 540210 -- Environment, Terrestrial-- Basic Studies-- (1990-)