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Ashland adds dam warning to budget By TONY BOOM ASHLAND - In just nine and a half minutes, a wall of water as high as 24 feet above Ashland Creek's bed would reach the Main Street Bridge and town's Plaza if Hosler Dam failed. The City Council has approved installation of an alarm system to warn of a dam break. The city's 2001-02 budget includes $200,000 for the project. City officials say a sudden failure of the dam is unlikely. An early warning system is required by the Federal Energy Regulatory Commission for dams producing electric power. The system will include two sensor arrays, a camera near the dam and warning horns. "The likelihood (of a break) is extremely small. The dam is in good shape. We have safety reviews every three years," said Ashland Public Works Director Paula Brown. "Twice a year we look at deflection. At no time have we seen anything that required us to do anything or make any changes." Hosler Dam is made of concrete that tends to get stronger if it does not suffer continuous damage, said Brown. Failures are more common in earth-filled dams, she added. An earthquake would probably cause the most damage to the dam, said Brown. Earthquake risk in this area is relatively low, but still a factor. The dam suffered no problems from earthquakes centered near Klamath Falls in 1993. Harza Engineering of Concord, Calif., ran computer models to determine the impact of a dam breakdown. Its inundation maps will be included in the city's revised Emergency Action Plan Simulations were run for both fair weather and wet weather dam breaks. Water levels are higher under the fair-weather scenario. The study showed a maximum water level increase of 5.4 feet in Phoenix in fair weather. The water would arrive there 2.8 hours after a break. In wet weather, an increase of 1.9 feet would arrive in 1.8 hours. "Because the canyon is steep and narrow, people would have to be ready to leave immediately," said Brown. "About 200 homes and businesses would be affected. Most are within one half block of Ashland Creek." Features will be built into the warning system to prevent false alarms. Two new sensor arrays just downstream from the dam will allow separate confirmation of a break. In addition, a camera would be placed at one of the sensor locations to allow additional monitoring. Soundings of alarms would be automated, with a brief time lag to allow for checking of the visual system and possible human intervention. Four alarms would be installed in Ashland. Another two might be placed near Talent, said Brown. She hopes to have the system ready to operate by the end of December. The department will seek firms to bids on a combined design and installation contract. Hosler Dam was built in 1928 to create Reeder Reservoir, the primary source of Ashland's drinking water. The dam is 25 feet thick at its base and 7 feet thick at its top. Harza's report says the dam is on a sound granite foundation. Reach Ashland bureau reporter Tony Boom at 482-4651, or e-mail [email protected] Mail Tribune Home | Ottaway Newspapers, Inc. | Dow Jones & Co., Inc. | Privacy | Contact Us Copyright � 2001 Mail Tribune, Inc.