THREE-DIMENSIONAL SEEPAGE ANALYSIS OF A COAL REFUSE PILE RECLAMATION

A coal refuse pile located in Greenbrier County, West Virginia was studied to restrict generation of acid mine drainage through the use of a cap and cover system. This paper presents results of a finite element method seepage analysis on a proposed reclamation design. The proposed reclamation incorporates a cap and cover system with a 0.3-m thick surface vegetation cap layer over a 0.6-m thick low permeability layer. The low permeability layer is directly above the coal refuse. Unsaturated soil mechanics was utilized, adopting the Fredlund and Xing equation for soil-water characteristic curve (SWCC) estimation. SWCC fitting parameters were calculated using the Zapata and the Hernandez estimation techniques. Different precipitation events were used to evaluate seepage throughout the reclamation area and assess the effectiveness of the cap and cover system. A steep area (>4H:1V) and a flat area were considered. The water balance analysis showed a 50% to 88% reduction in water volume at the coal refuse layer and a reduction in the time for the refuse to return to initial water content due to the cap and cover system implementation. Moisture detainment was observed in the growth layer and is important for supporting vegetation persistence.

PENNSYLVANIA’S ABANDONED MINE LAND (AML) EMERGENCY PROGRAM

The Pennsylvania Department of Environmental Protection’s Bureau of Abandoned Mine Reclamation (BAMR) implements an Abandoned Mine Land (AML) Emergency Program to address high-priority, abandoned mine land (AML) problems that suddenly occur throughout Pennsylvania’s coal fields. BAMR maintains two field offices: one in eastern Pennsylvania (Anthracite Region) in Wilkes-Barre and one in western Pennsylvania (Bituminous Region) in Ebensburg. Both field offices maintain in-house construction crews with significant equipment available to respond to and address many small AML Emergencies (hazards) such as pothole (or cavehole), subsidences, and mine drainage breakouts. For larger AML Emergencies such as subsidence events causing structural damage to homes, businesses, and roads; mine fires; coal refuse fires; landslides; or other large-scale or complex AML problems, projects are completed by outside contractors. Project designs are completed by BAMR engineering staff. The contractors are then hired through solicitation of bids or proposals with very short timeframes between bid issue and bid opening. Since October of 2010, BAMR has addressed nearly 800 AML Emergencies which equates to approximately 80 AML Emergency projects each calendar year. The average construction cost to address those emergencies was just over $3.25 million per year. Due to the increased precipitation over the Commonwealth the last several years, that number has increased to an average of 86 AML Emergency projects over the last five (5) years (2015–2019) with a record number of 127 addressed in calendar year 2018. The average cost to address those AML Emergency projects over that five-year period was $4.66 million per year. This paper will provide some background on Pennsylvania’s AML Emergency Program, some summary statistics including the annual number and types of projects completed including costs, and also highlight through both photos and video links some typical projects recently completed by the program.