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Nonmechanical dewatering of the regional Floridan Aquifer system

Sydney T. Bacchus
Nonmechanical dewatering of the regional Floridan Aquifer system (in Perspectives on karst geomorphology, hydrology, and geochemistry; a tribute volume to Derek C. Ford and William B. White, Russell S. Harmon (editor) and Carol M. Wicks (editor))
Special Paper - Geological Society of America (2006) 404: 219-234

Abstract

The regional Floridan aquifer system has been dewatered and otherwise altered extensively throughout much of Florida and coastal Georgia by groundwater pumpage (mining). An increasing threat to this karst aquifer system is structural mining of aquifer formations, primarily to produce fertilizers, titanium products, construction materials, and pet food supplements. These excavations often include mechanical dewatering to facilitate shallow and deep extraction of the aquifer formations. All include reduced aquifer levels, dewatering of the aquifer system, and altered hydroperiods at and surrounding the excavated pits, due to increased void space and evapotranspirative losses (nonmechanical dewatering). Only mechanical dewatering is considered by regulatory agencies during evaluations of applications for structural mining of the aquifer system. Despite refuting data, open pits resulting from these excavations increasingly are portrayed as subsurface "reservoirs" that create new or enhanced sources of water in areas where natural groundwater supplies have been depleted. Four permits and sites were evaluated for excavated and proposed pits in SE, NW, SW, and east-central Florida's natural areas used for groundwater supply. The combined surface area for pits under those four permits will result in approximately 237,000 m (super 3) /d ( approximately 62.7 million gallons per day [Mgd]) of induced discharge from the regional Floridan aquifer system due to nonmechanical dewatering. This volume is more than twice the reported pumpage from the combined three municipal supply wells at the Miami-Dade West Well Field. The approximately 123 ha ( approximately 308 ac) SW Florida mine, most recently excavated in an area designated as critical habitat for the federally listed Florida panther, will result in induced aquifer discharge of approximately 1505 m (super 3) /d (0.4 Mgd) due to nonmechanical dewatering. This loss is equivalent to approximately 5% of all water used by domestic supply wells in that county in 1990. That recently initiated excavation in SW Florida revealed environmental damage extending beyond the mine boundaries, to surrounding private property,and is the first documented case of such damage solely from aquifer formation mining and nonmechanical dewatering of the aquifer system. A federal court ruled on 22 March 2006 that the U.S. Army Corps of Engineers and U.S. Fish and Wildlife Service had failed to carry out their duty to protect the federal wetlands and protected species by issuing permits for mining in the SE case-study area.


ISSN: 0072-1077
EISSN: 2331-219X
Coden: GSAPAZ
Serial Title: Special Paper - Geological Society of America
Serial Volume: 404
Title: Nonmechanical dewatering of the regional Floridan Aquifer system
Title: Perspectives on karst geomorphology, hydrology, and geochemistry; a tribute volume to Derek C. Ford and William B. White
Author(s): Bacchus, Sydney T.
Author(s): Harmon, Russell S.editor
Author(s): Wicks, Carol M.editor
Affiliation: Applied Environmental Services, Athens, GA, United States
Affiliation: U. S. Army Research Office, Environmental Sciences Division, Research Triangle Park, NC, United States
Pages: 219-234
Published: 2006
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
ISBN: 978-0-8137-2404-1
ISBN: 0-8137-2404-7
References: 49
Accession Number: 2006-075418
Categories: Hydrogeology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 2 tables, sketch map
N25°10'00" - N26°00'00", W80°54'00" - W80°07'60"
Secondary Affiliation: University of Missouri-Columbia, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute.
Update Code: 200643
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