OasisLMS

Abstract: The Blue Ridge is famous in Virginia for Shenandoah National Park and the Blue Ridge Parkway. Less known is Virginia’ s extensive karstic geology west of the Blue Ridge, within the Valley and Ridge region, extending from Maryland to Tennessee, paralleling Interstate 81.

Various open pit and underground limestone mines operate in the area, including a mine near Roanoke, which experienced a sudden increase in water subterranean water inflow in March, 2020. The water inflow exceeded the in-place dewatering system, resulting in water rising approximately 8 feet per day, or roughly 25 million gallons per day.

Previous flooding events were associated with sinkholes opening up in and adjacent to a stream flowing along the mine’ s service road and railway. Operators identified two different new sinkholes in the stream whose appearance was associated with the increase in inflow.

This paper will review the geology of the site, the sinkhole features which opened up, and repair methods evaluated. It will also review environmental constraints which significantly impacted the repair design process due to endangered fish in the stream.

Grouting of the sinkholes was performed using potable water certified plural component polyurethane. Polyurethane reduced environmental, covid-related logistics and on-site life safety risks. Lastly, the paper will review lessons learned during repair, and the dynamic environment encountered. This included multiple new sinkholes opening, two of which caused movement in adjacent bridge abutments, bringing VDOT into the process in the middle of the project.

Kirk Roberts; Dustin Roberts

Annual Conference Proceedings