AWWA ACE63155

AWWA ACE63155 Assessing and Managing PCCP Water Transmission Mains: Baltimore County, Maryland - A Case Study
Conference Proceeding by American Water Works Association, 06/01/2006

Donaldson, Frank H.; DiLego, Thomas J.; Higgins, Michael S.; Padewski, Edward A.; Keller, Bruce F.

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Baltimore County, Maryland has implemented a state-of-the-art assessment andmanagement program for one of their PCCP water transmission mains. Thetransmission main is 48-inch supply feeder from a major pumping station to a largefinished water reservoir. A major focus of their assessment program has been to utilizenon-destructive techniques to assess the main and identify actively corroding PCCP.The program consisted of two phases: electromagnetic testing simultaneously withvisual inspections for Phase 1; and, acoustic monitoring for Phase 2. The Phase 2program was subsequently revised based upon the results from the initial Phase 1inspection and the simultaneous availability of evolving technologies.Phase 1 results showed that approximately 16 percent of the pipe sections comprisingthe 1.5 mile pipeline inspected exhibited wire breaks. Four pipe sections wereidentified as requiring immediate replacement before the main could be returned toservice. Subsequent to pipe replacement, the four pipe sections were dissected as a partof forensic analysis. The actual number of wires broken were compared with thosepreviously predicted using the electromagnetic inspection techniques.Following the Phase 1 inspection, the County's Phase 2 assessment program wasmodified to incorporate new technology which uses "fiber optics" in lieu of the planned"acoustic" technology. The fiber optic technology is being used to monitor on-goingwire breakage over a 90-day period. In addition, and for trial purposes, bothtechnologies are also being compared side by side for a short section of the pipe beingmonitored.The paper uses the case study of the Baltimore County main to discuss corrosionmechanisms of PCCP, to review the latest technologies and methodologies available toassess the PCCP main, and to critique the results stemming from their employment inthe pipeline assessment and management program. Includes reference, tables, figures.