The city of Tempe is another step closer to approving a plan that again will replace the dam for Tempe Town Lake, an attraction the city touts as one of the top tourist destinations in the Grand Canyon state.
The Tempe City Council will discuss Thursday whether to spend approximately $36 million for a hydraulically-operated hinged crest steel gate for the dam.
The recommendation emerged from a short of list of three options [http://evtnow.com/tempelake]— including the Sumitomo rubber dam and Obermeyer gate options — reviewed by Gannett Fleming, a third party firm that the city hired to review the issue last summer at a cost of $367,000. The steel gate option will be recommended, however, because of longterm durability, the hydrology of the river, public safety and cost effectiveness, according to Tempe assistant city manager Jeff Kulaga.
After Thursday’s meeting, the public may provide input on the issue at 5:30 p.m. on Jan. 11 at the Tempe Arts Center. The council will formally vote on the type of dam at it’s Jan. 19 meeting.
“We were looking at longterm durability,” Kulaga said of the recommendation. “The hinged crest gate does not require rubber at all. It provides more durability under weather conditions, and in our case, the Arizona heat. The cost of the rubber bladder option kind of surprised us.”
Based on initial construction costs of $41 million and an additional $138 million over a 50-year life cycle, the rubber bladder was eliminated from consideration. Initial construction costs for the hinged crest gate and the Obermeyer gate are $35 million and $33, respectively.
In addition to maintenance costs, the desert climate ages the rubber bladders prematurely — which contributed to one of the bladders bursting in July 2010 and causing the lake to be drained.
The empty lake triggered the cancelation of the Soma Triathlon, translating to an economic impact loss of $550,000, said Toni Smith, communication manager of the Tempe Convention and Visitors Bureau. Had the Ironman Triathlon been cancelled, the city would have lost nearly $4 million of economic impact.
When the lake was empty from late July to mid-October, the spectacle drew more visitors than in a normal summer, she said. But boaters, fishers and rowing teams had to go elsewhere.
However, the $36 million cost for the steel gate option does not include the cost of an east dam or pump system — an estimated $8 to $10 million.
The bid and procurement construction contract is expected to be awarded by Oct. 2013 with construction starting that following month. The rubber bladders would be in place during construction of the gates, so the lake would not have to be drained.
Financing options will also be reviewed at the Jan. 19 meeting, but voted on at a later date.
Financing options for the project include voter approved bonds or sale of city property, among other options.
Tempe has a December 2015 deadline to replace the bladders under an agreement with Bridgestone Industrial Products, which made the dams. Before Tempe replaced the bladders last summer, it negotiated for four west-end bladders at virtually no cost to Tempe. Bridgestone told Tempe to expect 20 to 30 years of use when the bladders were installed in 1999, but a 2006 inspection found they were aging faster than anticipated and needed replacement. The bladders had a 10-year warranty.