Bilberry Dam
On February 5, 1852 , the Bilberry Dam broke at Holme Village near Holmfirth in England ( Yorkshire ) and caused the "Holmfirth Flood". There were at least 80 deaths.
The construction of the dam
Construction of the dam began in 1840 to drive the water wheels of the mills in the Holme Valley. The design engineer was Mr. George Leather, Civil Engineer, and the construction was carried out by Messrs. Sharp and Sons of Dewsbury for £ 9,324. The contract was withdrawn from this company and continued by Messrs. David Peter and Brothers until 1848.
The dam had a storage volume of 300,000 m³. The dam lay in a narrow gorge behind a basin that was fed by two rivers. The grass-covered earth and stone dam was 67 feet (20 m) high and 300 feet (90 m) long. It had a vertical sealing layer in the center that was 8 feet (2.4 m) wide at the top and 16 feet (4.8 m) wide at the bottom.
A circular tower with a diameter of 4.5 m, which was supposed to drain overflowing water through a tunnel, stood in the dam as flood relief . The dam settled later, so that the dam crest was lower in the middle than the flood overflow, making it useless. There were also two locks in the tower that could be operated with slides from above.
A spring as thick as an arm was found during construction. The subsoil was dug deeper here to seal the place. In spite of this, the dam was later very leaky during operation, so that some of the watermills could be operated solely from seepage water. The engineer later claimed in court that he did not know about the source. The cause of the dam breach , however, was overflow.
The catastrophe
The dam was destroyed in a flood after days of heavy rainfall. It is said to have rained 2 inches (50 mm) in 24 hours. The night before the break, one of the two fasteners was under repair and the other was blocked with stones and rubble. The water level could not be lowered. As a result, the dam was washed over by wind and waves until it broke.
It took the water 20 minutes to cover the three miles (5 km) to Holmfirth. Great damage was done in the Holme Valley. The number of deaths is given as 80, 81 or 84 and there were many homeless. The reservoir ran out in 30 minutes.
Today the Digley Reservoir, built in 1954, is a little further below.