Hydrology and water quality of the Eocene Wilcox Group: significance for lignite development in East Texas
Lignite development will place major demands on ground-water supplies. The Simsboro Formation and the Calvert Bluff Formation (a major lignite-bearing unit) of the Wilcox Group between the Colorado and Trinity Rivers constituted a test case to evaluate the availability and quality of ground water. Aquifer geometry (sand) was determined by comparing environmental geologic maps with subsurface sand-percent and net-sand maps constructed from electric logs (Kaiser, 1978). The combined maps correlate well and show that the Calvert Bluff Formation consists of a complex interfingering of coarse channel sands and fine interchannel muds. Sand outcrop areas occupying approximately 10 square miles separate much larger interchannel areas with few and minor sands. The Simsboro Formation consists of two parts - thick multilateral sand (300 to 700 ft) in most of the southern outcrop belt and a series of channel sands (100 to 200 ft) interspersed with muds in the northern belt. Sands of the northern Simsboro belt are more like the Calvert Bluff channel sands than like the thick Simsboro sands. Available hydrologic data suggest that Simsboro and Calvert Bluff sands have high hydraulic conductivity (6 to 20 m/day); interchannel muds have low hydraulic conductivity (1 to 2 m/day). Water compositions in the Simsboro and Calvert Bluff sands are similar and evolve similarly. Shallow ground water has a Ca-Mg-Cl-HCO/sub 3/ composition low in total dissolved solids (less than 500 mg/l). The water evolves over a depth range from 300 to 1200 ft to become a Na-HCO/sub 3/ water. Change in composition probably results from ion exchange with clays (Ca/sup + +/ for 2Na/sup +/) and solution of calcite (which contributes more Ca/sup + +/ for exchange and increases HCO/sub 3//sup -/ concentration). Poor quality water is largely restricted to shallow wells (less than 100 ft) in muddy parts of the Calvert Bluff Formation.
- Research Organization:
- Univ. of Texas, Austin
- OSTI ID:
- 6473703
- Journal Information:
- Trans., Gulf Coast Assoc. Geol. Soc.; (United States), Journal Name: Trans., Gulf Coast Assoc. Geol. Soc.; (United States) Vol. 29; ISSN TGCGA
- Country of Publication:
- United States
- Language:
- English
Similar Records
Lignite occurrence in relation to depositional facies, Eocene Wilcox group, Sabine uplift area, east Texas - regional and local comparative studies
Hydrogeochemistry of the unsaturated zone at Big Brown lignite mine, East Texas
Related Subjects
010900* -- Coal
Lignite
& Peat-- Environmental Aspects
520100 -- Environment
Aquatic-- Basic Studies-- (-1989)
520500 -- Environment
Aquatic-- Site Resource & Use Studies-- (-1989)
54 ENVIRONMENTAL SCIENCES
AQUIFERS
BROWN COAL
CARBONACEOUS MATERIALS
CENOZOIC ERA
COAL
COAL MINING
ENERGY SOURCES
ENVIRONMENTAL EFFECTS
ENVIRONMENTAL QUALITY
FOSSIL FUELS
FUELS
GEOLOGIC AGES
GROUND WATER
HYDROGEN COMPOUNDS
HYDROLOGY
LIGNITE
MATERIALS
MINING
NORTH AMERICA
OXYGEN COMPOUNDS
RESOURCES
ROCKS
SANDSTONES
SEDIMENTARY ROCKS
SOUTHWEST REGION
TERTIARY PERIOD
TEXAS
USA
WATER
WATER QUALITY
WATER RESOURCES