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Tempe Town Lake dam collapse blamed on heat, age by Derek Quizon - Sept. 23, 2010 12:00 AM The Arizona Republic Heat and age were the main causes of the July 20 Tempe Town Lake dam collapse, according to a report released Wednesday by an independent consulting agency. In August, the city commissioned Ohio consulting firm SEA Ltd. to investigate the cause of the dam failure. Parts of the collapsed dam's rubber bladders were sent to the firm's laboratory to be tested. Tempe split the $50,000 cost of the study with Bridgestone, the manufacturer of the bladders, according to city spokeswoman Kris Baxter-Ging. The report concludes that the layers of the rubber dam began to separate because of a breach in a portion of the dam near the concrete apron. The breach worsened over time, and deterioration was made worse by "extremely high" temperatures in excess of 100 degrees, according to the report. The report does not say what caused the initial breach. Tempe released a statement Wednesday saying it accepts the results of the study and has decided to move on. Assistant City Manager Jeff Kulaga clarified that the city is not saying it was responsible for the dam's failure but that it agrees with SEA's findings. "We're moving forward to safely reopen the lake on time and on schedule," he said. SEA's report contained no recommendations on a replacement dam, Kulaga said, because the company was not contracted for that purpose. The results of the report have not changed plans for bladder replacement in November, but Kulaga said the city would "take into consideration the findings" of the report when making plans for a longer-term dam replacement. Bridgestone, the manufacturer of the bladders, signed a warranty in 1999 guaranteeing the rubber bladders would last 10 years. In 2007, Bridgestone warned city officials that the dam was deteriorating faster than expected. The projected $14 million price to replace them made officials wary of replacing the bladders at the time. Don Darden, a spokesman for Bridgestone, said the results of the study validated the company's assertions that heat was shortening the lifespan of the bladders. "There was nothing surprising in the findings for us," he said.
Independent report: Heat, sun caused dam burst at Tempe Town Lake Posted: Wednesday, September 22, 2010 4:01 pm Dan Zeiger, Tribune An independent examiner has determined that years of heat and sun exposure to aging bladders caused the damage that led to a section of the western dam at Tempe Town Lake giving way on July 20. SEA Ltd. inspected one of the 11-year-old dam bladders at its Columbus, Ohio, facility and concluded in a nine-page report that "intra-carcass pressurization" - separation of internal layers - led to the burst. "Experts in the field have cited the age and heat combination as the reason," said Jeff Kulaga, Tempe assistant city manager. "We are accepting that evaluation and are moving forward." Before the burst, Kulaga said, Bridgestone determined that the bladders were deteriorating faster than expected and arranged an agreement with Tempe to replace them at no cost to the city. "The jointly-commissioned report confirms what Bridgestone said as early as 2007 about the climate conditions and the long-term effects the environment has had on the rubber bladders in Tempe," James Wheeler, director of operations and finance for Bridgestone, said in a statement. The four bladders are being replaced - the lake is expected to open in early November - and precautions will be taken to protect them from the sun. They will be shaded by a new pedestrian bridge, and a sprinkler-watering system will provide additional cooling. Under those conditions, the bladders should last for the duration of a five-year lease agreement between Bridgestone and Tempe. By November 2015, a long-term dam structure will be in place, and Kulaga said that a bladder system and a steel-hinge gate are among the options. "The report from SEA and our experience with rubber bladders will all be taken into account in our future analysis of a (long-term structure)," Kulaga said.
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