Managing Risk in Real Time: Tucson Water’s 15-Year Monitoring Program for PCCP

The City of Tucson is a Sonoran Desert community in Southern Arizona with a population of nearly 750,000 people, and one million people when including the metropolitan areas. Tucson Water, a department of the City of Tucson, is a large, complex groundwater system receiving a Colorado River water allocation of approximately 148,000 acre-feet. The city recharges this groundwater system in a vast recharge and recovery system west of the community. In February of 1999, the city’s largest potable water transmission line, a 96-in. diameter (4,000 mm) prestressed concrete cylinder pipeline (PCCP), failed catastrophically, releasing a flood of water, mud, rock, and debris, crashing into a neighborhood, knocking down block walls, trapping people in homes, floating vehicles out of driveways, and causing extensive damage to private property and homes within the community. This one failure of a pipeline having been in service just 11 years cost the city approximately five million dollars in private property damage, collateral damage, and litigation, and forced the city to revert to pumping native groundwater for months until the transmission line was restored to service. The forthcoming white paper will demonstrate how one water utility recovered from the catastrophic failure of its most critical water transmission line, progressed to one of the most forward-thinking water utilities, and implemented one of the most advanced and longest running asset management programs for PCCP in North America. This “snapshot” presentation of Tucson’s asset management program, entitled “Pipeline Protection Program” (PPP), will give a brief overview of the various challenges Tucson faced and highlight the various strategies, tools, and technologies applied that have collectively prevented any additional pipeline bursts for more than 23 years and counting.