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

Abstract

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 increased 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. Rechargemore » 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. 23 refs., 19 figs., 25 tabs.« less