Hydraulic Properties of Surface Mine Spoils of the Northern Appalachian Plateau

Abstract

Abstract. Aquifer tests were conducted on over 125 mine spoil wells from 18 surface mines located in Pennsylvania, West Virginia, Ohio, and Kentucky. These tests (primarily slug tests) were used to determine the range, variability, and predictability of surface mine spoil hydraulic properties (hydraulic conductivity and transmissivity). Test results show that hydraulic properties of mine spoil aquifers are highly variable and relatively unpredictable. Hydraulic conductivity ranged over 7 orders of magnitude from a very low permeability of 4.45 x 10·• mis to a highly transmissive 7 .58 x 10· 2 mis. The hydraulic conductivity measured at mines with 5 or more wells frequently ranged over 3 orders of magnitude and none ranged less than one. A few statistical relationships between geologic and mining conditions and the hydraulic properties were observed. Spoil aquifers that were under 30 months old and those over 100 months old exhibited significantly lower (95 percent confidence level) hydraulic conductivities than those between 30 and 100 months old. The influence of spoil lithology on the hydraulic conductivity does not appear to be strong, probably because of masking by other factors introduced during reclamation. No significant trends were observed between spoil thickness and hydraulic conductivity. A comparison of hydraulic conductivity derived from slug and constant-discharge tests performed on the same wells indicate that slug tests tend to yield lower values. A few spoil wells exhibited an oscillatory water-level response during slug testing, similar to that observed during testing of some karst and glacial aquifers.

Electrical resistivity imaging of hydrologic flow through surface coal mine valley fills with comparison to other landforms

“…Therefore, if TDS generation could be limited in valley fills, downstream water quality may improve. Previous hydrologic studies of valley fills have focused on valley fill effluent (Murphy, Hornberger, & Liddle, 2014) or falling-head tests in groundwater wells (Hawkins, 1998(Hawkins, , 2004Hawkins & Aljoe, 1992;Wunsch, Dinger, & Graham, 1999). These approaches allow only limited understanding of flow regimes and essentially no understanding of the internal structure of valley fills and associated rock-water interactions that elevate TDS.…”