When multiple subsidence events occur in close proximity, a potential solution is to grout the mine void to minimize future ground movement. Grouting projects involve drilling a series of boreholes into the mine voids and filling those voids with a concrete-like mixture. This mixture hardens into pillar-like formations that support the mine roof and greatly reduce the likelihood of future subsidence events. These grouting projects focus on public infrastructure such as roads and schools because private property can be protected through mine subsidence insurance.
Previous grouting projects have taken place at the Terre Haute Regional Airport, the State Road 62 Bridge near Chandler, and Loge Elementary School in Boonville. Extremely subsidence-prone neighborhoods in Linton and Coalmont have undergone grouting of residential streets and associated utility lines, and areas of Boonville are planned for grouting in 2014. Stretches of heavily-traveled county roads have also been grouted, and more such projects are being scheduled.
