DAM FAILURE BLAMED ON DESIGN, CORROSION.Byline: Nancy Vogel Scripps-McClatchy Western Service In the first official report about last summer's failure of a spillway spillway, n a channel or passageway through which food escapes from the occlusal surfaces of the teeth during mastication. The occlusal, developmental, and supplemental grooves, as well as the incisal, occlusal, labial, buccal, and lingual embrasures, gate at Folsom Dam Folsom Dam is in Northern California about 25 miles northeast of Sacramento on the American River. The dam is in Sacramento County and forms Folsom Lake. Folsom Dam is a concrete gravity dam, which depends on its weight to hold back the lake. , engineers said the gate may not have been lubricated lu·bri·cate v. lu·bri·cat·ed, lu·bri·cat·ing, lu·bri·cates v.tr. 1. To apply a lubricant to. 2. To make slippery or smooth. v.intr. To act as a lubricant. frequently enough to fend off unseen corrosion. They also blamed the accident, which dropped Folsom Lake Folsom Lake is a large reservoir in Northern California about 25 mi (40 km) northeast of Sacramento. The lake is formed by Folsom Dam, constructed in 1955 to control the American River. by 40 percent last summer, on a 40-year-old gate design that was too weak to handle the friction caused by that corrosion. The preliminary report, issued Friday by the U.S. Bureau of Reclamation, promises to influence inspection and maintenance on dams like Folsom across the world because it focused on big hinge pins called trunnions - hidden, hard-to-reach pieces of spillway gates that get no routine scrutiny. Already the U.S. Army Corps of Engineers has begun more frequent greasing of such pins on some of its dams, and the state's Division of Dam Safety has begun training its inspectors in mountain-climbing techniques to reach the gates. Operators of similar dams in Japan, Australia, Italy and Canada have requested the report. ``If nothing else, others have started learning from our unfortunate incident,'' said Chuck Howard
Howard was a production assistant at Edgar J. , project manager for the bureau. When the garage-door-like gate wrenched apart as it was being raised July 17, the bureau faced possible culprits from sabotage to rust. But after analyzing pieces of the broken gate in 25 kind of tests, federal and state engineers have concluded the problem lay hidden on the two hollow steel pins, 2-1/2 feet in diameter, on which the gate pivots. Those pins are wrapped in brass and housed in a steel casing. The steel pin moves against the brass under incredible pressure, especially when the lake is full. Gate No. 3 was lifted 85 times in its life, according to according to prep. 1. As stated or indicated by; on the authority of: according to historians. 2. In keeping with: according to instructions. 3. bureau records, but on July 17 corrosion that had built up on its right trunnion trun·nion n. A pin or gudgeon, especially either of two small cylindrical projections on a cannon forming an axis on which it pivots. [French trognon, stump.] pin triggered a force stronger than the dam's designers anticipated in 1948. To ease such friction, grease is supposed to be injected into the trunnions every day when the lake is high enough to push against the gates, according to the operating manual the corps wrote when it designed Folsom Dam. But for the last 15 years, the Years, The the seven decades of Eleanor Pargiter’s life. [Br. Lit.: Benét, 1109] See : Time bureau, which operates the dam, has been lubricating the gates monthly, not daily, when water presses on the gate. Gate No. 3 was greased 10 days before it broke, according to the report. The corps, too, has been lubricating the spillway gates on some of its dams monthly, not daily. |
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