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JAN 10,2000 CA-METRO-WATER-DISTRICT) Final Report Confirms
Operational Error Caused Pipeline Rupture in Orange County
LOS ANGELES--Jan. 10, 2000-Operational error triggered a pressure surge in a main water artery providing imported supplies to 700,000 south Orange County residents, causing the large-diameter pipeline to rupture last month, according to a final incident report released today by Metropolitan Water District. The four-page report, presented to a committee of Metropolitan's board of directors, confirms the results of MWD's initial investigation into the Dec. 13 rupture of the district's Allen-McColloch Pipeline on the outskirts of Irvine, Calif. "In meeting a request from the Santa Margarita Water District for a flow increase at one of the pipeline's 25 service connections, there was an error in the way its valves were operated," said Jill T. Wicke, manager of MWD's water system operations. "Over the course of just a few minutes, the system operator inadvertently opened and then quickly closed the isolation valves at the service connection. This created a pressure surge, or water hammer, that traveled up and down the line, causing the rupture," said Wicke, who detailed to the board's engineering and operations committee the events leading up to the rupture. Working around the clock, Metropolitan crews repaired the 69-inch pipeline in seven days, returning the line to service Dec. 20. Throughout the emergency, Metropolitan was aided by South County consumers who pitched in and conserved water, helping maintain water services to communities most affected by the rupture. "It's been said that emergencies tend to bring out the best in people. That was certainly the case for Metropolitan following the event on the Allen-McColloch Pipeline," Wicke said. "This experience underscored the value of teamwork, preparedness, response, cooperation, coordination and communication." As a precautionary measure, in February, Metropolitan plans to shut down, drain and inspect the nine miles of the line's pre-stressed concrete pipe. Prior the rupture, Metropolitan planned to inspect the pipeline, stretching from Yorba Linda to Lake Forest, later in the year. Following the rupture and repair, Metropolitan also has instituted a series of operational safeguards along the line, including efforts to standardize the pipeline's control system programming to ensure that it's compatible with the rest of MWD's distribution network. In addition, the district plans to expand its standard operating procedures for the pipeline and related service connections; modify operational procedures and facilities based on a surge analysis; document operational procedures; reevaluate operator practices and communications and provide continuing operator training and familiarization with the pipeline and related facilities. As in the preliminary findings, Metropolitan's final report confirms that corrosion, seismic activity, material defects and manufacturing defects were not present and did not factor in the rupture. The report also finds that about 18 million gallons were lost through the rupture. Metropolitan initially estimated that 5 million gallons were spilled at the rupture site along Portola Parkway. Metropolitan's estimate for pipeline repairs is $650,000 - about $100,000 less than the district originally projected. The repair cost will be absorbed into Metropolitan's operation and maintenance budget and will not impact water rates. |