North Central Correctional Institute Steam Tunnel
The reinforced concrete utility tunnel at the North Central Correctional Institute (NCCI) is over 100 years old. As part of a utility upgrade, NCCI sought to remedy observed displacement and distress of the tunnel walls. Working for the utility contractor, SGH designed repairs to extend the useful life of the tunnel.
SGH completed the following as part of our condition assessment:
- Documented the location and extent of concrete distress
- Collected information about the existing concrete thickness and embedded reinforcement by using ground penetrating radar and exploratory openings
- Measured lateral displacement of the tunnel walls
- Evaluated the effectiveness of existing horizontal bracing
We observed corrosion-related concrete deterioration, including deterioration of the doweled reinforcement at the roof/wall intersection. The existing horizontal bracing did not fully engage the walls and partially led to cracking at the wall mid-height.
SGH determined that the tunnel walls were rotating at the base and that the walls would likely experience more displacement in the future. We provided a temporary stabilization design that included new lateral and kicker bracing to supplement the existing bracing. We designed lightweight and field-adjustable braces that are less obtrusive than the existing and could accommodate varied wall conditions and geometry.