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New Jersey counts cost of freak rainstorm that causes failure of 24 dams

ENGINEERS IN New Jersey, USA rushed to install a 40m long temporary truss deck to replace a highway bridge swept away in floods that caused the total or partial failure of 24 dams last month.

No lives were lost when freak weather dumped more than 300mm of rain in one night on Burlington County, but hundreds of residents had to flee when the dams failed.

In all 13 earth dams up to 7m high collapsed or were breached, while another 11 were partially breached or overtopped.

Abutments of the 10m span Route 70 crossing of Friendship Creek in Southampton collapsed after embankments were washed out, dropping the deck into the river.The bridge carried 17,000 cars a day.

Engineers from the state's department of transportation used two 550t cranes to install the 150t, 40m long steel truss temporary bridge.

Most of the dams that collapsed were built in the first half of the 20th century or earlier and some had already been strengthened. Bad weather in 1999 and 2000 prompted the state to make $95M (£65M) available last year for testing and repairs to unsafe dams.

In its last survey New Jersey Department of Environmental Protection engineers estimated that 317 of the state's 1,600 dams represented a Class 2 significant hazard - a risk of serious property damage if they fail, but no great risk to life, a spokesman said. In the past 15 years, 51 dams are said to have collapsed.

'We've doubled our dam inspectorate staff from eight to 16 since the last failures and all but three of the dams that failed this time had been inspected in the last three years, ' he said.

Surviving Class 2 risk dams are now being inspected again.

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