Date of Graduation

2017

Document Type

Thesis

Degree Type

MS

College

Statler College of Engineering and Mineral Resources

Department

Civil and Environmental Engineering

Committee Chair

John D Quaranta

Committee Co-Chair

Leslie Hopkinson

Committee Member

Hema Siriwardane

Abstract

The Royal Scot coal refuse pile in Greenbrier County, WV is being studied in order to reduce the Acid Mine Drainage (AMD) produced by this site. Two approaches to solve this problem were proposed: 1) a hydraulic barrier cover reclamation with a surface vegetative layer and 2) a land cover slope reclamation with a vegetative growth layer placement at the surface.;This thesis evaluated seepage and slope stability of the two proposed designs with a finite element modeling software in a transient analysis under unsaturated soil mechanics. Results from the model analysis were evaluated and further utilized to compare and contrast the cost benefit of both reclamation approaches. The Soil-Water Characteristic Curve (SWCC) was calculated using the Fredlund and Xing (1994) equation and the parameters estimated by the Zapata (1999) and Torres (2011) estimations.;The hydraulic barriers was modeled with 3 different soils: 1) in situ (as it is on site), 2) 60% coarse refuse and 40% fine refuse and 3) 80% coarse refuse and 20% fine refuse. Infiltration reduction averages of 26% for the 60/40 barrier and 35% for the 80/20 barrier were calculated. Although the 60/40 ratio had more fines in its composition, the aggregation of fines shifted the GSD curve to a larger particle size, consequently increasing the effective diameter and resulting in a higher hydraulic conductivity. Slope stability modeling showed that both proposals resist sliding failure with a Factor of Safety greater than 2.0.;A cost estimation for the hydraulic barrier was developed and faced with the cost for the land cover reclamation. The estimated amount for the barrier cover was {dollar}2,959,493, while for the land cover reclamation was {dollar}2,288,385.;The AMD treatment cost at the site is expected to be reduced by 35%, proportional to the reduction in infiltration by the 80/20 hydraulic barrier design. Cost assessment for the AMD treatment at this site was performed, predicting a reduction of {dollar}59,167 per year on chemicals from the land cover reclamation to the hydraulic barrier, which will represent a 10 year cost break-even from one design to the other after the beginning of the construction.

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