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Potentiometric and Aquifer Property Changes Above Subsiding Longwall Mine Panels, Illinois Basin Coalfield
Author(s) -
Booth Colin J.,
Spande Erik D.
Publication year - 1992
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.1745-6584.1992.tb02004.x
Subject(s) - aquifer , geology , bedrock , cone of depression , longwall mining , overburden , subsidence , sinkhole , oil shale , structural basin , water table , groundwater , coal mining , geomorphology , artesian aquifer , mining engineering , karst , geotechnical engineering , coal , paleontology , engineering , waste management
This study examined the response of potentiometric levels and hydraulic properties to subsidence caused by a 725‐ft‐deep active longwall mine in southern Illinois. The overburden is mainly shale but includes a shallow sandstone aquifer, overlain by a shale aquitard, capped by thin drift. Pumping and packer tests indicate that subsidence fracturing increased the hydraulic conductivities of the sandstone aquifer by about an order of magnitude, and of certain horizons of the lower bedrock by several orders. The water table in the drift aquifer was unaffected by mining; however, heads in the bedrock units dropped sharply in response to subsidence, probably because tensional dilation of fractures increased storativities. The sandstone aquifer also displayed gradual potentiometric declines ahead of mining, and a rapid partial recovery afterwards. Depression of water levels and potentially higher well yields represent conflicting negative and positive aspects of the hydrologic impact of longwall mining.