In early 2023, the U.S. Army Corps of Engineers (USACE) had identified and begun tracking stress fractures in a small adit tunnel at Mt. Morris Dam; an important flood control dam on the Genesee River in upstate New York. Merco was contracted to lead the rehabilitation and stabilization efforts for the tunnel.

The USACE had initially proposed using traditional steel sets and concrete work to reinforce the tunnel. After initial planning, it became evident that this approach was not possible due to extremely difficult access to the work area. The adit tunnel was only accessible through the dam’s lower gallery, meaning all equipment and materials would have to have been transported down a long narrow hallway, and up several flights of stairs to the work area. It would have been difficult to impossible to meet budgetary and schedule restraints while utilizing this repair method.

Merco instead proposed and implemented a novel repair method utilizing carbon fiber wrap technology to stabilize the tunnel while also maintaining the original tunnel opening size. In addition, Merco utilized a long-line helicopter lift in order to mobilize materials and equipment to the work area and was able to save weeks of mobilization time and costs.

Merco worked closely with Kilduff Underground Engineering to design the unique repairs. In addition to the carbon fiber wrap, chemical grout injection was utilized to fill cracks and voids behind the tunnel liner. After the tunnel was stabilized, a new concrete façade was poured along with a brand-new tunnel entrance door to repair the exterior concrete work while maintaining the original look of the dam that was originally built in 1952.