ABSTRACT
Sewer renewal technologies that are currently used for the repair, replacement and/or rehabilitation of deteriorating wastewater collection systems are generally effective, but there is room for improvement of existing technologies and for the development of new technologies. Many utilities are seeking innovative rehabilitation technologies, particularly for large-diameter pipes. However, information about these emerging technologies is not always readily available. As part of the U.S. Environmental Protection Agency’s Aging Water Infrastructure Program, a field demonstration program of innovative rehabilitation technologies was initiated with the purpose of: (1) gathering reliable performance and cost data for new technologies; and (2) making the capabilities of these technologies better known to the industry. This paper describes the demonstration of corrosion testing for a spray-applied geopolymer mortar during the rehabilitation of a 60-inch reinforced concrete pipe approximately 25 feet deep in Houston, TX. The demonstration section was 165 feet of severely deteriorated pipe that terminated at a wastewater treatment plant (WWTP). Unique aspects of this project included: (a) use of an innovative and emerging large-diameter structural rehabilitation technology on a severely deteriorated pipe located beneath a large open stormwater channel; (b) an independent, third-party assessment of the technology; and (c) difficult flow control issues at the WWTP.
INTRODUCTION
As the state of infrastructure around the world decays, more cost-effective solutions to repair large diameter pipe systems are required. Typical dig and replace technology is often not practical because in most urban areas these degrading pipes are located directly under other critical infrastructure, such as major roadways, buildings or other assets. As the diameter of these pipes becomes larger (more than 48 inches), the cost of many of the traditional trenchless technologies becomes exponentially more expensive and often requires significant excavation around access points that present additional issues related to community disturbance, traffic control, noise and general disruption. For example, if a 48-inch diameter sewer pipe was located in the center of town, and a standard 30- or 36-inch manhole was the access point, a cured-in-place pipe (CIPP) repair would require an access hole of at least at least the least the diameter of the host pipe, which can be significantly larger than as standard manhole. While other techniques, such as slip-lining, would require an even greater excavation diameter for an access hole to install new liners. Additionally, with many of the standard trenchless repair technologies, other issues related to either the shape (round, arched, elliptical) or the layout (straight, curved, bends of various radius) can make these repair technologies impractical, while based on application method spray applied linings can generally be applied around these various anomolies.1,2