Moccasin Hollow Coal Refuse Disposal Facility

This West Virginia life-of-mine coal preparation plant and associated refuse disposal facility turned to Schnabel for a complex project involving design, consultation, and construction monitoring.

The work involved the design of a five stage, 370-foot-high coal refuse tailings impoundment. Impoundment stages included a 250-foot high starter dam embankment with clay core and core trench seepage cutoff built entirely of segregated mine overburden materials (6 zones and 1.8 million cubic yards). Additional stages were built using plant generated coarse coal refuse as borrow materials, applying centerline and upstream construction methods.

Dam designs featured open channel spillways in rock, Armorform-lined spillways, HMWPE pipe spillways, numerous rockfill underdrains, and French drains. The project’s embankment dam design included complete foundation exploration and testing programs, as well as laboratory testing programs to develop and verify materials parameters. In the impoundment stages, Schnabel conducted hydrologic and hydraulic analyses of the probable maximum flood (PMF), embankment dam seepage analyses using finite element methods and associated drain designs, detailed stability analyses including post-earthquake and deformations analyses, and the evaluation of upstream construction stability. The firm also developed permit packages for submittal to MSHA and state WVDEP regulatory authorities, and we’ve continued to provide construction management, weekly inspection monitoring services, and annual certification of the facility since 2004.