The Development of a Landfill over an Abandoned Limestone Mine

The first case history deals with the expansion of a landfill over a 56 ha abandoned room and pillar limestone mine in Kansas City area. A massive 7 ha mine-roof collapse had occurred in the mine and fissures were discovered on the surface. The State of Kansas required that the mine be backfilled to avoid any surface subsidence. This project did not follow our standard site characterization strategy. Work at this site began with the single task of using a borehole video camera to evaluate the extent of mine collapse and the effectiveness of fly ash being used to backfill the mine. The project slowly evolved into a substantial site characterization effort that included an assessment of mine collapse, monitoring mine-roof collapse conditions over time, a groundwater monitoring plan for the landfill and a subsidence risk assessment along with many other tasks. The project was carried out over a period of 7 years from 1987 to 1993 with minor efforts in mine backfilling continuing through 2003. About half of the project effort was completed underground in the mine.