Dams are built to confine and check the flow of water so that it can be used for irrigation, electric power generation and drinking water. They also are built to control flooding. Civil engineers choose the design and materials that are best suited for the project by analyzing foundation conditions, load strains, temperature and pressure changes, chemistry of local groundwater, and the probability of earthquakes. Modern dams usually are embankment (earth, rock, gravel) or masonry (concrete). Embankments Embankments are used across broad rivers because of the low cost and availability of material and because earth and rock tend to shift and adapt to the movement of the dam foundation. The majority of the material used is highly compactable and stays in place because of its tremendous weight. Unfortunately these materials, if used by themselves, can be eventually washed away by the water. So Civil engineers must design a way for the water to seep through the structure safely or stop the seepage all together.
Situated at the head of the Peace River Canyon, the Bennett Dam is one of the world's largest earthfill dams, holding back one of North America's largest reservoirs, Williston Lake.
In 1996 a two-foot-wide sinkhole was discovered on the road atop the massive dam. Test drilling revealed a second sinkhole in the 29-year-old structure (18 feet deep and nine feet wide) with another 100 feet of soft material below. The repairs to the sinkholes were completed in 1997.
Gardiner Dam was built 1959-1967 on the South Saskatchewan River, 25 Km downstream of Elbow, Saskatchewan. The volume of earthfill was 65,000,000 cubic metres making it also one of the world's largest earthfill dams.
The Barrier Dam and Plant were completed in 1947. The earthfilled dam is 706 m long, 43 m high with a 46 m head (the vertical height from which the water falls). Barrier Plant was TransAlta's first hydro plant operated by remote control. The reservoir has a relatively small storage capacity (25 billion litres), so Barrier is still considered a run-of-the-river plant. That means it uses river water as it flows, with a minimal storage reservoir.
Rock Filled Dam - This dam was built to form a stocked recreational fishing pond in Kananaskis Country of Alberta. The fishing pond is a buffer between the anglers and the trout in the high mountain streams.
The Eastside Reservoir Project (Diamond Valley Lake) in California is the largest earth and rockfill dam in the history of the United States and the winner of the 2000 outstanding Civil Engineering Achievement Award of Merit.
The building of this reservoir will provide a source of water in the event of an emergency, such as a major earthquake, in the event of a drought and for the times of the year when demand is high. The reservoir is constructed in an open valley using three earth and rockfill dams and the mountains. All the rock and earth used came from within the reservoir boundaries. More than 30 million tons of rock were excavated and crushed for use in the dams. In order to preserve habitats and protect the wildlife the Metropolitan Water District added 9,000 acres to a nearby wildlife reserve. Want to know more? - Masonry Dams |
Bennett Dam
