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Title: Ground water flow in a fractured carbonate aquifer inferred from combined hydrogeological and geochemical measurements

Abstract

A conceptual model for ground water flow is presented for a fractured Silurian dolomite in the Niagara Escarpment area of southern Ontario. Such a model is necessary to facilitate remedial efforts of a PCB-contaminated site located in Smithville, Ontario. Both physical and chemical hydrogeological observations obtained from field investigations were used to deduce the structure of the ground water flow system in the fracture network. The field study was conducted using observations obtained from six bore-holes drilled in the vicinity of the town of Smithville. The boreholes were diamond cored through the entire thickness of the dolomite formation (approximately 45 m), hydraulically tested using a 2 m packer spacing and then completed using multipacker casing strings. Measurements of hydraulic head were obtained on a weekly basis over a period of two years, and ground water from each borehole interval was collected for geochemical analyses for inorganic and isotopic composition. Transmissivity measurements indicate that the dolomite is divided into two ground water flow systems separated by an extensive unit of low transmissivity that is pervasive throughout the region. The upper flow system is characterized by water enriched in Mg{sup 2+} and SO{sub 4}{sup 2{minus}}. Below the low transmissivity zone, ground watermore » increases in salinity and is enriched in Ca{sup 2+} and SO{sub 4}{sup 2{minus}}. Based on the geochemistry, the rate of ground water migration in the lower flow system is surmised to be much less than that in the upper system. Measurements of hydraulic head in conjunction with the results of the analyses of the environmental isotopes ({delta}{sup 18}O and {delta}{sup 2}H) suggest that ground water flow is mainly horizontal and likely governed by enlarged bedding plane fractures. These isotope geochemistry and topographical features further suggest that ground water recharge is occurring approximately 2 km to the north of Smithville.« less

Authors:
; ; ; ; ;
Publication Date:
Research Org.:
Univ. of Waterloo, Ontario (CA)
OSTI Identifier:
20080436
Alternate Identifier(s):
OSTI ID: 20080436
Resource Type:
Journal Article
Journal Name:
Ground Water
Additional Journal Information:
Journal Volume: 38; Journal Issue: 3; Other Information: PBD: May-Jun 2000; Journal ID: ISSN 0017-467X
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; GROUND WATER; REMEDIAL ACTION; POLYCHLORINATED BIPHENYLS; GEOLOGIC FRACTURES; FLUID FLOW; GEOCHEMISTRY; MATHEMATICAL MODELS; ONTARIO; HYDROLOGY; GEOLOGY

Citation Formats

Zanini, L., Novakowski, K.S., Lapcevic, P., Bickerton, G.S., Voralek, J., and Talbot, C. Ground water flow in a fractured carbonate aquifer inferred from combined hydrogeological and geochemical measurements. United States: N. p., 2000. Web. doi:10.1111/j.1745-6584.2000.tb00220.x.
Zanini, L., Novakowski, K.S., Lapcevic, P., Bickerton, G.S., Voralek, J., & Talbot, C. Ground water flow in a fractured carbonate aquifer inferred from combined hydrogeological and geochemical measurements. United States. doi:10.1111/j.1745-6584.2000.tb00220.x.
Zanini, L., Novakowski, K.S., Lapcevic, P., Bickerton, G.S., Voralek, J., and Talbot, C. Thu . "Ground water flow in a fractured carbonate aquifer inferred from combined hydrogeological and geochemical measurements". United States. doi:10.1111/j.1745-6584.2000.tb00220.x.
@article{osti_20080436,
title = {Ground water flow in a fractured carbonate aquifer inferred from combined hydrogeological and geochemical measurements},
author = {Zanini, L. and Novakowski, K.S. and Lapcevic, P. and Bickerton, G.S. and Voralek, J. and Talbot, C.},
abstractNote = {A conceptual model for ground water flow is presented for a fractured Silurian dolomite in the Niagara Escarpment area of southern Ontario. Such a model is necessary to facilitate remedial efforts of a PCB-contaminated site located in Smithville, Ontario. Both physical and chemical hydrogeological observations obtained from field investigations were used to deduce the structure of the ground water flow system in the fracture network. The field study was conducted using observations obtained from six bore-holes drilled in the vicinity of the town of Smithville. The boreholes were diamond cored through the entire thickness of the dolomite formation (approximately 45 m), hydraulically tested using a 2 m packer spacing and then completed using multipacker casing strings. Measurements of hydraulic head were obtained on a weekly basis over a period of two years, and ground water from each borehole interval was collected for geochemical analyses for inorganic and isotopic composition. Transmissivity measurements indicate that the dolomite is divided into two ground water flow systems separated by an extensive unit of low transmissivity that is pervasive throughout the region. The upper flow system is characterized by water enriched in Mg{sup 2+} and SO{sub 4}{sup 2{minus}}. Below the low transmissivity zone, ground water increases in salinity and is enriched in Ca{sup 2+} and SO{sub 4}{sup 2{minus}}. Based on the geochemistry, the rate of ground water migration in the lower flow system is surmised to be much less than that in the upper system. Measurements of hydraulic head in conjunction with the results of the analyses of the environmental isotopes ({delta}{sup 18}O and {delta}{sup 2}H) suggest that ground water flow is mainly horizontal and likely governed by enlarged bedding plane fractures. These isotope geochemistry and topographical features further suggest that ground water recharge is occurring approximately 2 km to the north of Smithville.},
doi = {10.1111/j.1745-6584.2000.tb00220.x},
journal = {Ground Water},
issn = {0017-467X},
number = 3,
volume = 38,
place = {United States},
year = {2000},
month = {6}
}