Physical, mechanical, and hydraulic properties of coal refuse for slurry impoundment design

Coal mining processes result in two general types of by-products: coarse coal refuse (CCR), a mixture of soil and rock commonly used to construct an impoundment coal refuse dam or embankment, and fine coal refuse (FCR) slurry, a mixture of soil, rock dust, coal fines and water that is pumped into such an impoundment. The physical, mechanical, and hydraulic conductivity properties of CCR and FCR are critical in designing coal refuse disposal dams and impoundments for both static and seismic stability. This paper provides a summary of laboratory and in-situ strength, and hydraulic conductivity test results performed on CCR and FCR in association with the design and construction of several coal refuse dams and impoundments in England and Western Pennsylvania in the United States. Predominant mean values and statistical variabilities are reported for each material property. These parameters are subsequently employed in a simple statistical model to evaluate the reliability of the design of coal refuse impoundments.