2000 Progress Report: Evaluation of Natural Amelioration of Acidic Deep Mine Discharges for Watershed Restoration

EPA Grant Number: R825794
Title: Evaluation of Natural Amelioration of Acidic Deep Mine Discharges for Watershed Restoration
Investigators: Dzombak, David A.
Institution: Carnegie Mellon University
EPA Project Officer: Packard, Benjamin H
Project Period: June 1, 1998 through May 31, 2001 (Extended to September 30, 2001)
Project Period Covered by this Report: June 1, 1999 through May 31, 2000
Project Amount: $610,484
RFA: Ecosystem Restoration (1997) RFA Text |  Recipients Lists
Research Category: Ecological Indicators/Assessment/Restoration , Hazardous Waste/Remediation , Land and Waste Management , Ecosystems

Objective:

The overall goal for the project is to identify the hydrologic and geochemical factors responsible for improvements over time in the quality of water discharges from abandoned deep mines. A related goal is to evaluate the effects of mining methods and abandoned mine management practices on long-term changes in mine water quality.

Progress Summary:

The project involves study of a set of mine water discharges associated with abandoned, interconnected mines in the Uniontown-Connellsville area of Western Pennsylvania. Almost all the deep-minable coal was removed from this area prior to 1970, and an extensive baseline study of mine discharges in the area was conducted in 1974-75 in conjunction with Operation Scarlift (Scarlift). New water quality monitoring was initiated in July 1998, at 21 of the abandoned mine drainage (AMD) sites studied previously, and was completed in 2000. The degree of mine water quality improvement since 1974-75 is being assessed. The local environment for each discharge also is being studied to relate observed changes in mine water quality to factors such as the extent of mine flooding and the chemistry of the rock overlying the mined area. The Pennsylvania Department of Environmental Protection (PADEP) is collaborating with the project.

AMD Monitoring?Uniontown Syncline Basin. In Year 3 of the project, flow and water quality monitoring was completed at the 21 selected AMD discharge locations in the Uniontown Syncline, Fayette County, Pennsylvania. The syncline plunges from the north and from the south creating a canoe-shaped coal basin. The Youghiogheny River splits the basin into two distinct regions: the northern portion and the southern portion. The mines in the northern portion are low-cover mines developed updip (upgradient) from the surface entries, which has resulted in freely draining discharges and unflooded mine voids. Deep mining in the northern portion of the basin was complete by the 1930s, and the discharges have existed since that time. The mines in the southern portion cover a larger area and include mine voids with up to 600 ft of overlying soil and rock (overburden). The deep mines were developed either downdip from the surface entries or updip from deep shafts, resulting in flooded mine voids. Deep mining in the southern portion was mostly completed by 1960, and the discharges began subsequently.

Field Data Evaluation. The field data have been compiled, checked, and plotted in various ways and interpretations of the field data have been undertaken. Comparison of the mine water quality data collected in this study and in Scarlift indicates that flooding has an important role in the change of AMD from acid to alkaline. Discharges from flooded mines were either alkaline in the Scarlift study, or have become alkaline since Scarlift. A substantial decrease in sulfate concentrations and a slight decrease in iron concentrations occurred between 1974-1975 and 1998-2000 in the flooded mine discharges. The discharges from the unflooded mines remained acidic over the same period and sulfate concentrations remained relatively high and constant. The constant sulfate concentrations in the unflooded mine and the decreased concentrations in the flooded mines reflect the decreased production of acid in the flooded mines and the relatively constant high acid production in the unflooded mines. The iron concentration in the unflooded mines was negligible in the Scarlift data and is still negligible.

Hydrologic and Chemical Modeling. Full interpretation of the monitoring data will require hydraulic analysis coupled with geochemical modeling. For hydraulic modeling, a box modeling approach has been adopted in which hydraulically separated mine areas are represented as simple tank reactors. The model has been applied to describe the hydrologic and mine discharge data collected to date. Initial geochemical modeling efforts focused on the development of a chemical model for abiotic pyrite oxidation.

Overburden Analysis and Modeling. Bore hole logs for several surface mines and shaft sections of old underground coalmines in Uniontown Syncline have been obtained. This information is being used to construct stratigraphic models, stratigraphic cross-sections, and fence diagrams of the Uniontown Syncline to gain insight into overburden geology and delineate its layering. Acid-base accounting leach test data are being collected from surface mine permits. This information will be used to calculate the net-neutralization potential of the geological units in the overburden. The final objective of overburden modeling and analysis is to estimate the net acidity and alkalinity of water infiltrating into the mine voids.

Future Activities:

In Year 4, we will be continuing the evaluation of the 1998-2000 monitoring data and completing the overburden analysis for the Uniontown Syncline. Knowledge of the overburden composition will be important for assessing the acid-neutralizing capacity of the water infiltrating into the mine voids in basin recharge areas. Finally, we will be working on coupling of a geochemical model with the tank reactor hydraulic model for the mine network for assistance with interpretation of the monitoring data.

Journal Articles:

No journal articles submitted with this report: View all 17 publications for this project

Supplemental Keywords:

coal, ecosystem, EPA Region 3, geochemistry, groundwater, land, metals, Mid-Atlantic, mining, natural attenuation, reclamation, restoration, sulfates, watersheds, acid mine drainage, Pennsylvania, PA., RFA, Scientific Discipline, Geographic Area, Water, Ecosystem Protection/Environmental Exposure & Risk, Water & Watershed, Wastewater, Environmental Chemistry, Ecosystem/Assessment/Indicators, Ecosystem Protection, Restoration, State, Ecological Effects - Environmental Exposure & Risk, Ecological Risk Assessment, Ecology and Ecosystems, Aquatic Ecosystem Restoration, Watersheds, Ecological Indicators, aquatic ecosystem, ecological exposure, watershed, Pennsylvania, underground coal mine, Appalachia, limestone drains, acid mine drainage, aluminum, geochemistry, ecological recovery, iron, manganese, aquatic ecosystems, ecosystem restoration, water quality, acid mine discharge, water treatment, ecosystem response , watershed restoration, ecological response, ecological restoration, PA

Relevant Websites:

http://www.ce.cmu.edu/~acidmine
http://www.ce.cmu.edu/~dzombak

Progress and Final Reports:

Original Abstract
  • 1998
  • 1999 Progress Report
  • Final Report