It was erected in 1982 in response to the disastrous floods of 1968, and it has helped to minimize flood risk for 965 homes and 300 businesses in Tonbridge. The Environment Agency defines it as a 1.3km-long, 5-metre-high earth wall that spans the Medway valley. The wall is made up of layers of soil and stone that have been carefully chosen to provide maximum flood protection while not being harmful to the environment. In addition to its role in reducing flood risk, the wall provides a number of other benefits. It forms part of the Medway Trail, a long-distance path that runs from London to Rochester. The wall also provides a screen for views to some properties that it borders, and it helps to preserve the character of the area by preventing development on floodland. The wall was designed by Mott MacDonald and built by Carillion at a cost of £12.5 million. It is expected to last for at least 100 years. Floods are one of England's most deadly natural disasters. They can take many forms, from small streams or rivers that overflow their banks during heavy rain, to large tidal surges that wash away roads and bridges. Flooding can also occur when the ground gives way under buildings or roadsides due to erosion or subsidence.