Hydrogeochemical data of coal strip-mine spoil near Macon in north-central Missouri
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D. C. Hall
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Ground-water movement and effects of coal strip mining on water quality of high-wall lakes and aquifers in the Macon-Huntsville area, north-central Missouri
Glacial drift and Pennsylvanian bedrock were mixed together forming spoil during pre-reclamation strip mining for coal in north-central Missouri. This restructuring of the land increases the porosity of the material, and increases aqueous concentrations of many dissolved constituents. Median sodium and bicarbonate concentrations were slightly greater, calcium 5 times greater, magnesium 6 times greater, manganese 15 times greater, iron 19 times greater, and sulfate 24 times greater in water from spoil than in water from glacial drift. Median potassium concentrations were slightly greater, and chloride concentrations were two times greater in water from glacial drift than in water from spoil. Water types in glacial drift and bedrock were mostly sodium bicarbonate and calcium bicarbonate; in spoil and lakes in the spoil, the water types were mostly calcium sulfate. Median pH values in water from spoil were 6.6, as compared to 7.4 in water from glacial drift and 9.0 in water from bedrock. Neutralization of acid by carbonate rocks causes the moderate pH values in water from spoil; a carbonate system closed to the atmosphere may result in alkaline pH values in bedrock. Transmissivities generally are greatest for spoil, and decrease in the following order: alluvium, glacial drift, and bedrock. Recharge to spoil is from precipitation, lateral flow from glacial drift, and lateral and vertical flow from bedrock. The rate of recharge to the aquifers is unknown, but probably is small. Groundwater discharge from the glacial drift, bedrock, and spoil is to alluvium. The direction of flow generally was from high-wall lakes in the spoil toward East Fork Little Chariton River or South Fork Claybank Creek. Significant differences (95% confidence level) in values and concentrations of aqueous constituents between spoil areas mined at different times (1940, 1952, and 1968) were obtained for pH, calcium, magnesium, manganese, sulfate, chloride, and dissolved solids, but not for iron. These differences are attributed to local variations in the geohydrologic system rather than spoil age. (Lantz-PTT)
Missouri↗
A description of the hydrologic system and the effects of coal mining on water quality in the East Fork Little Chariton River and the alluvial aquifer between Macon and Huntsville, north-central Missouri
The quality of surface and groundwater has been affected by abandoned strip mines and by abandoned underground mines in a 110-sq mi subbasin of the East Fork Little Chariton River. More than 14% of the area was strip mined for coal before 1979. The hydrologic system in the area was investigated and the effects of coal mining on quality of water in the river and alluvial aquifer were analyzed, with major emphasis on defining strip-mining effects. The groundwater gradient was from glacial drift or coal spring to alluvium to the East Fork Little Chariton River, and was greatest in spring and least in fall. Seepage from alluvium to the East Fork Little Chariton River occurs throughout the year, except during drought conditions when the only river flow is water released from Long Branch Lake. In the East Fork Little Chariton River median dissolved-solids concentrations increased from 153 mg/L near Macon to 630 mg/L near Huntsville and median sulfate concentrations increased from 36 mg/L near Macon to 360 mg/L near Huntsville. The median dissolved-solids concentration in water from the alluvium increased from 408 mg/L upstream from the strip mines to 641 mg/L near the mines and median dissolved-sulfate concentration increased from 140 to 350 mg/L. The sulfate-to-chloride ratio, used as the most sensitive indicator of strip-mining effects, increased markedly downstream in the East Fork Little Chariton River and nearby Middle Fork Little Chariton River, which also is affected by strip mining. There were no significant increases in sulfate-to-chloride ratio and dissolved-solids concentrations in comparable nearby subbasins of the Grand, Thompson, and Chariton Rivers where there was no mining. (Author 's abstract)
Water-Resources Investigations Report↗