An Analysis of Household Water Supply Impacts by Underground Coal Mining in Virginia: Executive Summary

Virginia Center for Coal and Energy Research

An Analysis of Household Water Supply Impacts by Underground Coal Mining in Virginia;
Carl E. Zipper, Willam Balfour, John Randolph, and Richard Roth.
VCCER 94-02. 34 pp. May 1994.
Currently, there is not a .pdf version of this report. For the full report, please contact the Center

Executive Summary:

Underground coal mining can affect wells and springs used as water supplies by rural residents. In some U.S. coal-mining areas, research has been conducted to address the effects of underground mining on groundwater resources and household water supplies. In the Virgina coal mining region, however, no published studies of mining impacts on water supplies are available. Such information is relevant to curent concerns due to recent federal and state legislation.

In this study, we analyzed the results of 73 investigations of alleged househole water supply impacts by underground mining in Virginia. These investigations were conducted by the Virginia Division of Mined Land Reclamation (VDMLR) between 1981 and 1987 for the purpose of resolving disputes between surface residents and underground mining firms. The results were analyzed with reference to guidelines for identifying the zone of subsidence influence on groundwater prepared by West Virginia University geologist Henry Rauch for use in the northern Appalachians. Rauch's guidelines use mathematical relationships to define a primary zone of underground mining influence where dewatering of aquifers is to be expected. Rauche's guidelines also include reference to mitigating factors such as rock type, subsurface features, and surface topography.

The VDMLR data set included 27 investigations of alleged water supply impacts by partial-extraction room-and-pillar mines, 41 investigations of high-extraction room-and-pillar mines, and 4 investigations of longwall mines.

The VDMLR investigations found 14 of 16 water supplies within the primary zone of influence defined by Rauch as likely to have been affected by pillar-retreat mining. No water supplies within Rauch's primary zone of influence for longwall and room-and-pillar mines were represented by the data base. In addition, VDMLR investigators found 42 of 56 water supplies outside of Rauch's primary zones were likely to have been affected by mining; these cases represented room-and-pillar, pillar-retreat, and longwall mining. Geologic circumstances not directly related to subsidence were found to be responsible for 31 of these 42 impacts. These geologic circumstances included subsurface fractures and other geologic features acting as aquifers which were drained by underground mining operations.

VDMLR investigators also found some of the investigated water losses to have been caused by factors other than mining; all such water supplies were located outside of Rauch's primary zones.

The VDMLR data contain no information on the time required for recovery of affected water supplies.

The VDMLR investigations provided limited support for the accuracy of Rauch's guidelines as a means of identifying situations where underground mining operations would be expected to impact groundwater aquifers and water supplies in Virginia. Data set limitations are the primary factor which prevents the drawing of more definite conclusions. The data do demonstrate that it would be inappropriate to rigidly define a "zone of underground mining impact" on water supplies in Virginia based solely on mine subsidence effects.