How Are Dams Removed?
Many people think that when a dam is removed it is simply blown up. The truth is that it is only in rare occurrences that explosives are used to remove a dam and make excavation easier. In most cases blowing up a dam is not feasible because of the environmental damage that the explosion would cause or the dam’s location in a fairly urban area.
The exact removal of a dam depends on the size of the dam and a number other factors. A dam may be removed entirely “in the dry” with the river being diverted or pumped around the site. There are also times when a dam is removed in stages, being slowly lowered over a number of years , to allow for a more paced restoration of the former impoundment.
There are also removals like the Elwha Dam where the impoundment is first drained and the submerged area allowed to dry prior to deconstruction. This process may take a year or more. To avoid damaging the stream during dam removal, the construction is undertaken in careful steps, almost surgically, to not only avoid stream damage but also to keep dam removal contractors, their equipment, and people downstream out of harm’s way. The most common way to remove a dam is described in more detail below.
Example: Bendigo State Park Dam, East Branch Clarion River, Johnsonburg, PA
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