Manual for Abandoned Underground Mine Inventory and Risk Assessment
Section 11: Preliminary and Final Development Applications
11.1 GENERAL DISCUSSION
The purpose of this section is to provide general guidelines for the integration of the Abandoned Underground Mine Inventory and Risk Assessment process into the roadway planning and design processes. Abandoned underground mine information should be considered an additional soils and/or underground structure consideration for roadway development. The process can be integrated into both roadway planning and design without modification.
The Abandoned Underground Mine Inventory and Risk Assessment process should be utilized as a planning and design tool to identify subsurface conditions and possible risks related to the presence of underground mines lying beneath single and multiple corridors studies, and existing or new alignments. It should be made a part of the Preliminary Development Phase (PDP) as described in the Transportation Development Process manual and the Final Development Phase (FDP) design investigations. A Section 2: Initial Informational Review should be performed for any roadway PDP or FDP in historically mined portions of the state. If the presence of abandoned underground is documented through such a review, then the process should be followed for the given PDP corridor(s), or the FDP existing or new alignments. As discussed in Section 2, the presence of unmapped mines should be considered.
NOTE: This process may reveal significant mine-related subsurface conditions either beneath the existing or proposed roadway, or in proposed cut slope or embankment areas.
11.2 PRELIMINARY DEVELOPMENT PHASE
The process should be used to develop individual mine location and risk assessment information, and also to summarize the aggregate mine-related risks and associated costs for single or multiple corridor studies. The advanced knowledge of this information may also allow for avoidance if recognized in the Stage I Study Areas portion of the PDP.
The PDP can utilize the entire process. By utilizing the process, any geotechnical investigations undertaken should be effectively directed to the highest priority sites on each study corridor. Section 7: Priority Site Investigation and Section 8: Priority Site Recommendations can serve as guidelines for conducting such geotechnical investigations and resulting recommendations. These priority site investigations should be conducted as necessary to characterize the nature of the mine-related subsurface conditions so that accurate assessment of them could be made for single or multiple corridor studies.
Specific points of the PDP process where the Abandoned Underground Mine Inventory and Risk Assessment process should be considered are:
Stage I Study Area, A. Inventory, 8. Geological ( or Stage I Study Area, B. Special Instructions)
Stage II, B. Feasible Alternative Segment, 2. Alignment and Profile and Cost Estimate ( or Stage II, E. Special Instructions)
Stage III Evaluation for Significance, E. Engineering ( or K. Special Instructions)
11.3 FINAL DEVELOPMENT PHASE
The FDP can utilize the entire Abandoned Underground Mine Inventory and Risk Assessment process. Utilization of the process will prioritize areas for consideration of investigation under a geotechnical investigation. Such geotechnical investigations can be undertaken effectively by directing them to the highest priority sites on each study corridor. Section 7: Priority Site Investigations and Section 8: Priority Site Recommendations can serve as guidelines for conducting such geotechnical investigations and evaluating the resulting data.
A large part of the Abandoned Underground Mine Inventory and Risk Assessment process should be integrated into the Part 1 Subgrade Stabilization (as required) and the Part 2 Subsurface Investigations.