Two design improvements are described as case histories. In 1983, a coal company in West Virginia requested field inspection of two conventionally reinforced, slip-formed concrete coal silos that had been built in 1974. Wall cracks previously repaired by epoxy injection had recracked, and spalling had accelerated. It was recommended that both silos be converted to concentric flow during discharge of the majority of the contents. In another example, a coal company in Ohio decided to increase its storage silo capacity. The coal to be stored was tested for granular flowability, bulk density, coefficient of laterial pressure, bulk modulus of elasticity, and material-wall friction over the range of moisture expected. These data were used to select the hopper configuration and design the silos and feeders.