CDM News - August 2007 - (Page 8)

Taking a Hard Look at Concrete Corrosion Corrosion has profound economic and social consequences for utilities and infrastructure, with its deteriorating effects potentially affecting public health and safety and costing an estimated $276 billion a year. Significant research has been conducted to characterize the corrosion processes of highly visible infrastructure, such as roads, electric utilities, and metal-reinforced bridges. However, the water treatment industry has traditionally perceived concrete corrosion as tolerable, leaving little known about the effects of water chemistry on critical out-of-sight drinking water distribution systems. Landmark Study Looks at Phosphate Inhibitors Following the advent of the Lead and Copper Rule (LCR), promulgated by the U.S. Environmental Protection Agency (EPA) in 1991, considerable research has guided the use of inhibitors to control soluble lead and copper in drinking water. Utilities can choose from a variety of these inhibitors, including phosphate and zinc phosphate, and although researchers understand their effects on lead and copper corrosion, surprisingly little is known about their corrosive effects on concretebased pipes and linings. That’s about to change. Complex Problem, No Simple Rules Specifically, the study will explore the interplay between water chemistry—a key determinant in corrosivity—and inhibitor performance. “There are often unintended hydraulic and water quality impacts in the distribution system when utilities use corrosion inhibitors at the plant,” explained Tracie L. Case, AwwaRF project manager. “This project will determine the impact of phosphate chemicals on the formation of protective scales, lime leaching, and water quality.” It won’t be easy. Combined with concrete’s heterogeneous composition, corrosion—and the study of it—becomes an exceptionally complex process. “Unfortunately, potable water chemistry is infinitely variable, so simple rules are hard to come by. Moreover, it is not possible to conduct expensive and time-consuming tests to identify the best combination of inhibitors for each water system,” explained Marc A. Edwards, Ph.D., co-principal investigator at Virginia Tech, who is joined by colleague Jeff L. Parks, Ph.D., to lead the investigation’s experimental phase. “Our challenge is to identify a few key factors that drive decisionmaking, and present their role in a simple way, such as a decision tree, so utility personnel can make reasonably accurate decisions associated with this complex problem.” CDM is collaborating with researchers at Virginia Tech University on a unique, 2-year project that is examining the impact of phosphate corrosion inhibitors on concrete. Funded by a cooperative partnership between the Awwa Research Foundation (AwwaRF) and EPA, this landmark study involves the participation of 20 water utilities from around the country, making it one of AwwaRF’s largest research projects and the first to systematically evaluate concrete infrastructure corrosion. “This AwwaRF project dives deep into a topic that has not been studied in detail. It has wide interest among our clients and CDM wanted to take a lead role due to our extensive utility experience and previous work in corrosion and water quality,” said Amrou Atassi, P.E., CDM project manager and co-principal investigator. “The results will aid utilities in selecting inhibitors that will protect public concrete distribution system pipes without compromising control of lead and copper leaching in schools and homes.” Detailed Study Represents Real Utilities The three-phase study began in January 2007 with the gathering of utility system data (e.g., LCR compliance and distribution system data, treatment technology, raw and finished water quality, pH,

Table of Contents Feed for the Digital Edition of CDM News - August 2007

Contents Envisioning Tomorrow’s Dublin Initiative & Innovation Stabilize Mercury Mines Preserving Old Town Alexandria Taking a Hard Look at Concrete Corrosion Perspective: Harnessing Bioenergy Engineering Better Lives CDM Announces Award-Winning Projects People Highlights

CDM News - August 2007

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