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Crews notched the coffer dam in the
location determined by engineers to promote
the optimum sediment dispersal. |
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The historic demolition of the Sandy River's Marmot Dam began July 2007 with the detonation of 4,400 pounds of ammonium nitrate and dynamite to remove the top of the dam.
Crews then mounted a campaign of blasting and drilling, reducing the dam to its concrete base. PGE finished the concrete demolition on Sept. 30. At that time, the coffer dam was extended across the river to block the bypass channel and fish diverted into a temporary fish passage system.
On Oct. 19, in response to rising water levels, the call was made to prepare for breaching. The sump pumps and fish passage system were removed, while heavy equipment filled in the diversion channel. Workers also dug... (continued)
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