CS15C - Concurrent Session 15C: Revitalizing Resilience: How Cured-In-Place Pipe Lining Helps Address Aging Infrastructure

Abstract Description: The state of Georgia has over 350 watershed dams that were designed and built under the NRCS during the 50’s, 60’s, and 70’s. Between ever-changing regulations, evolving design standards, and the unavoidable passage of time, these structures desperately need remediation to remain in service as they approach the end of their design life. But how do the owners balance the public benefit that these structures provide with the soaring prices of heavy civil construction and limited budgets?

Yellow River Dam No. 15 (Y-15) is an earthen embankment flood protection dam in Gwinnett County and is currently classified by both the NRCS and the Georgia Safe Dams Program as a high-hazard structure. Y-15 has previously been taken through the NRCS Dam Assessment and Supplemental Watershed Planning processes and received major upgrades in 2007 – including construction of a roller compacted concrete (RCC) stepped spillway that came with a five-million-dollar price tag. Now, almost 20 years later, Y-15 needs another round of rehabilitation.

Through the course of regular operations and maintenance inspections of Y-15, several deficiencies were identified, including an inoperable low-level gate, deterioration of the reinforced concrete riser, and cracking within the principal spillway conduit. Demolition and reconstruction of the principal spillway riser was selected as the preferred design alternative – but the biggest challenge was how to repair a 50-year-old conduit that was buried beneath an almost-new $5M spillway.

The traditional excavate-and-replace approach was out of the question, and sliplining appeared to be a low-cost option that would extend the service life of the conduit by 20 or 30 years. But sliplining also comes with its own unique challenges – namely how to maintain hydraulic capacity while drastically reducing flow area. Follow along through the evaluation process and how the design team worked in tandem with the Owner to evaluate various sliplining alternatives to maximize the longevity and economy of the Y-15 rehabilitation project.

Site photographs and video will be utilized to illustrate the CIPP lining process – starting with preparation of the host pipe, following the installation procedures and UV curing of the fiberglass liner, and wrapping up with a CCTV inspection of the interior of the newly-lined conduit.