Manual for Abandoned Underground Mine Inventory and Risk Assessment
Ohio Mine Manual Disclaimer
The ODOT Abandoned Underground Mine Inventory and Risk Assessment process documented in this manual is a proactive method for identifying and prioritizing, through risk assessment, sites where such mines exist beneath the roadway. These roadway locations represent an existing, undefined and yet possibly significant risk to the safety of the traveling public. At the outset of this process, the amount of work required for implementation and the existing threat to the traveling public, which all sites collectively represent, is undefined.
This process is designed to begin with an existing situation in which a roadway authority has an unknown number of sites at unknown locations having unknown levels of risk. The process then develops a comprehensive inventory of sites from existing information which ranks all sites into a logical, prioritized site risk assessment listing. This listing is then utilized to investigate, and remediate if necessary, the sites in a prioritized manner. The overall purpose of this inventory effort is to enhance the safety of the traveling public.
Prior to individual priority site investigations, all assessments of risk are made based on existing information and one site visit. The accuracy of the existing information is unknown. The form and amount of available information can vary greatly between the different sites. Actual subsurface conditions can also vary greatly between even closely spaced adjacent sites due to highly variable geologic conditions.
The Ohio Department of Natural Resources (ODNR), Division of Geological Survey (DGS) has detailed abandonment maps for over 4,000 underground mines. In addition to those mines for which detailed maps are available, the Division of Geological Survey estimates there are approximately 2,000 mines in Ohio for which no detailed maps of the mine workings are available. Therefore, implementation of the ODOT Abandoned Underground Mine Inventory and Risk Assessment will not identify and bring under risk assessment management those sites for which there are no records.
Due to the above-described variability of existing information and undocumented individual site geological conditions, subsidence events may still occur at identified sites prior to remediation being performed as a part of this inventory process. It is possible that subsidence events may occur within the roadway at sites with a lower priority ranking prior to sites with a higher ranking. It is impossible to predict the precise time and location of subsidence events. The process described in this manual is an attempt to identify roadway sites with the highest probability of future subsidence events and furthermore rank these sites with the greatest safety impact on the traveling public.