A friend sent along these great videos of a coffer dam being breached in super-fast speed. This video has since circulated the Internet extensively, but in case you haven’t seen it yet…
Marmot Dam Removal – ‘largest dam removal in Oregon’
This video shows the intentional breaching of a coffer dam, the final phase in a process to return the Sandy River to a free-flowing state.
Just like the Marmot Dam, most dams are finally demolished because of significant upkeep costs and concerns for fish.
So, what is the shelf-life of a dam?
Many dams constructed in the early 20th century are beginning to age and show signs of disrepair. The Association of State Dam Safety Officials (ASDSO) is keeping a watchful eye over the dams in America. With over 79,000 dams in the United States, the ASDSO supposes there are thousands (3,316 to be exact) of dams susceptible to collapse.
“…the number of dams identified as unsafe is increasing at a faster rate than those being repaired.”
The possible failure of a dam is probably the most likely contender for its removal. But, many environmental, socio-economic, aesthetic, and cultural benefits also occur with the removal of dams.
We Build Them…
World’s Five Largest Dams by Volume (completed and proposed)
Source of Data: InfoPlease
And, then we take them down…
Three Largest Proposed Dam Removals in the World (so far)
- If approved, four dams on the Klamath River in California and Oregon.
- Two dams on the Elwha River are cited for removal in 2012.
- Matilija Dam: Will this dam in Ventura County, California be removed?
American Rivers has compiled a list of dams removed from 1999 to 2007. They state around 713 dams have been removed, to date.