According to BBC:
Emergency work is under way to repair the Toddbrook Reservoir dam in Derbyshire after it was damaged by heavy rain.
About 1,500 residents were evacuated from Whaley Bridge on Thursday evening amid fears they were in "mortal danger".
Engineers pumped water out of the reservoir in an attempt to stop up to 300 million gallons of water bursting through the damaged dam.
An RAF Chinook is flying in repair materials to shore up the dam and dropping 400 tonnes of aggregate to stop more water getting in.
Toddbrook Reservoir - Facts 📐📚
Toddbrook Reservoir opened in 1838 as a feeder for the Peak Forest Canal. It is located near the town of Whaley Bridge in Derbyshire, England.
Catchment area: 1,700 ha (4,200 acres).
Surface area1: 4.6 ha (36 acres).
Max. depth: 24 m (79 ft).
Water volume: 1,288,000 cubic metres (283,000,000 imp gal).
Surface elevation: 185.69 m (609.2 ft).
Materials of dam: clay with sands and gravel.
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Type of embankment
The Toddbrook Reservoir dam uses an earth embankment system to retain the water mass of the reservoir.
The design of the dam has to account for:
#1 The Stability against sliding failure of the embankment.
#2 Seepage Through Embankment and Foundation.
#3 Seismic stability (Not applicable for UK dams)
Source: BBC, The Guardian