F W R J
Emerging Renewal Technologies for Pressurized Pipelines Steve Soldati
P
ipelines that carry flows under pressure represent a special set of challenges for water and sewer rehabilitation. Historically, most pressurized pipelines were rehabilitated using open cut construction. Part of the reason for that choice has been a lack of trenchless rehabilitation technologies appropriate for pressurized pipelines. A lack of investment in aging pressure pipe infrastructure, coupled with increasing congestion (both above and below ground) has accelerated development in the trenchless rehabilitation industry. This article reviews the concept of structural classification for pressure pipe linings as defined by the American Water Works Association (AWWA), and where emerging trenchless renewal technologies fit within the AWWA classification framework. Five case studies are presented that utilized separate trenchless products for pressure pipe rehabilitation: S Carbon or glass fiber-reinforced polymer (FRP) S Cured-in-place pipe (CIPP)
S T ight-fit high-density polyethylene (HDPE) pipe S Fusible polyvinyl chloride (Fusible PVC®) pipe S Hose lining system Discussed is the engineering, material construction, installation, and cost-effectiveness of each product with the intent to demonstrate the strengths and limitations of each.
The State of Aging Infrastructure The AWWA recently published its “2020 State of the Water Industry” survey, which identifies critical topics and tracks trends to help raise awareness within the water industry. This survey covers all aspects of the industry, including infrastructure assets, water quality, water resources, and agency staffing. The one thing that stands out the most from the report is that, for the fifth consecutive year, renewal and replacement of aging water and wastewater infrastructure, and financing for capital improvements, have ranked as the top one and two issues, respectively, facing the industry.
Steve Soldati, P.E., is regional sales manager of pressure pipe–east region with Aegion Corp. in Tampa.
The Cost of Doing Nothing Asset management 101 says that the longer the wait to address an aging asset, the more expensive it will be to replace, renew, or rehabilitate it. Take roadway pavement for example. Over time, as cars and trucks ride over the pavement, it slowly degrades and develops tiny vertical cracks at the surface. As the vehicle flows continue, those tiny cracks begin to propagate deeper into the pavement thickness. In the early years of these cracks, they are shallower, and it takes only a minimal thickness to remove and repave with new asphalt to restore the roadway free of cracks. If that same roadway, however, wasn’t repaved until several years later, those cracks would be much deeper (if not full depth), much more asphalt would need to be replaced, and therefore, it would increase the cost substantially. This causes a higher replacement cost, but is also much more disruptive to the traveling public and the local community.
Traditional Methods of Replacement and Its Hardships
Figure 1. Selection of rehabilitation techniques to resolve water quality problems.
44 July 2022 • Florida Water Resources Journal
The traditional method of addressing pressurized pipelines has been to dig and replace. This is a conservative method to restore structural integrity, improve water quality, protect pipes from further corrosion, and reduce maintenance costs. This method, in some instances, can be the best path forward, given that the pipeline is in an open space with easy access, little or no other utility conflicts exists, and/or the pipe depth is relatively shallow. The problem with many pipelines needing to be replaced today is that it isn’t always a preferred site condition that makes dig and replace a clear winner. There has been continued development built on top of existing pipelines, additional other utility infrastructures put Continued on page 46
