The Shawshank Rehabilitation

In 2021, the Indiana Department of Corrections in conjunction with the Indiana Department of Administration called on SAK Construction, LLC, to evaluate an 84″ CMP steam tunnel at the Putnamville Prison that was heavily corroded due to the high temperature and humid environment it was subjected to. A portion of the steam tunnel had previously collapsed, and after repair, the remaining tunnel was evaluated and deemed to be an emergency repair as several areas of the CMP had been deformed and breached and were allowing backfill to enter the utility tunnel. This paper will walk through the design-build process and first-of-a-kind design that was incorporated to tackle a unique and difficult constructability. The final solution that was reviewed and approved by all parties includes a multi-technology approach. The steam pipes are mounted on racks and cover the pipe wall from the 1 o'clock position to the 5 o'clock position. The steam pipes also could not be removed or taken out of service at any time during the rehabilitation process. This created two issues: one trying to repair the tunnel with limited access to parts of the circumference, and the second dealing with extreme temperatures varying from 90°F to 130°F. The initial solution was a combination of carbon fiber reinforced polymer from the 1 to 5 o'clock position and transitioning to a sprayed geopolymer from the 5 to 1 o'clock position. This was studied in the first 45 ft of the tunnel under what was deemed a pilot and completed in late 2022. The design accounted for the fact that the liner is under axial compression in addition to small flexural forces that induce small tensile stress on the inner surface of the liner at the crown that gradually changes into flexural compression on the inner surface of the liner at the springline. To handle these stresses and to address the limited accessibility in areas of the CMP, carbon fiber-reinforced polymer (CFRP) was selected for lining these areas. The use of CFRP also eliminated the concern of overspray and working in tight quarters around the steam pipes and pipe racks. While the pilot was deemed a success, a few issues arose due to the extreme heat in this section of the tunnel. Before moving forward with the remaining 990 ft of tunnel rehabilitation, a few design modifications were made. The modifications include a 100% solids epoxy liner versus carbon fiber for the 1 to 5 o'clock position, insulating all the steam pipes and incorporating additional environmental controls. Construction commenced on full tunnel rehabilitation in early Spring 2024 and will be completed by early 2025.