The Weekly Reflektion Week 08 / 2020

The Dale Dyke Reservoir embankment shortly following its collapse in 1864

This week’s Reflektion considers the Yorkshire dam disasters of 1852 and 1864.

Do you know where the requirements in the standards you use originated? Are you vigilant for signals that the standards could be improved?

 In the 19th century in Yorkshire, dams were being built to guarantee a supply of water for power for the many mills in the area, and as a source of drinking water for the rapidly increasing population. On the 5th February 1852, just before 0100 hrs, the Bilberry Dam, just above the town of Holmefirth, near Huddersfield in Yorkshire collapsed, the resultant flooding killed 81 people. The dam itself comprised ‘earth, stones, etc. such as the district supplied’, and was 300 feet (91 m) across and 67 feet (20,4m) high. As was normal for this type of dam, an impermeable ‘puddle’ built of clay and gravel lay at the heart of the dam to make it watertight. When constructing the ‘puddle’, a spring was encountered, that caused delays, and an attempt was made to re-route the spring to the upside of the dam. Midway through construction, the contractor was changed out, and the new contractor recommended strengthening the ‘puddle’ due to the spring they had encountered. This was rejected by the dam owners as they were already over budget.

After construction, the embankment settled noticeably, and, according to reports, the dam leaked continually from the day it was filled. At the base of the dam were 2 sluices to allow water to pass through the dam. In February 1852, one of the sluices was under repair, and the other was blocked with stones and vegetation. According to records, almost 2,5” (10 cm) of rain fell in the first 4 days of February filling the dam ‘higher than it had been seen before’. At about midnight, the dam began to overflow the embankment where it had settled, and about an hour later the dam collapsed causing 86 million gallons (390,000 m3) of water to rush through the sleeping town. Several families had taken the initiative to evacuate their homes close to the dam shortly before the collapse or the death toll could have been worse.

The dam was designed by George Leather for the water company, and he denied any knowledge of the spring the contractor had found, or the discussion regarding strengthening the ‘puddle’. The inquest found that the dam owners knew about the condition of the dam and should have emptied it and closed it down. They were found guilty of ‘gross and culpable negligence’ but were protected from prosecution by their membership of a corporation with limited liability.

12 years later, in 1864, John Leather, the son of George Leather, was the designer of the Dale Dyke Dam, near Sheffield, about 35 miles from the Bilberry Dam above Holmfirth. Leather both designed the dam and supervised its construction. On a stormy night, March 11th the dam was being inspected at 1730 hrs, and a crack, 12’ (3,6m) from the top of the dam, extending for about 150 feet (46m) was seen. This was evaluated as not being a threat to the integrity of the dam, but a team went back later in the evening to check. By about 1900 hrs, the crack had widened so that ‘a man’s finger’ could be inserted, and it now extended vertically down the dam face, although no leaks were seen. The resident engineer was sent for to evaluate the crack, and when he arrived, at about 2200 hrs, the crack was wide enough to insert ‘a man’s fist’. While considering the options for reducing the water level, even though the dam was not full, the dam collapsed at 2330 hrs, releasing 710 million gallons (3,2 million m3) of water into the valley, killing 244 people.

The engineering profession at this time possessed a well-reputed weekly magazine, The Engineer, which stated “Its (Dale Dyke Dam) fall, coupled with that of the failure of the Holmfirth reservoir … show that the practice of civil engineering is far from what it should be … The broken dam was constructed much according to the ordinary practice in such works. It failed nonetheless.“ The court criticized the design and the construction of the dam, and the accident led to reforms in engineering practice and in standards on specifics that needed to be met when constructing such large-scale structures as the Dale Dyke Dam.

We work in an industry with a requirement for continual improvement. Although we use industry standards in much of our work, standards are continually developing, sometimes due to changes made following major accidents. Do you know what the requirements in the original standards your facility was built in accordance with are? Do you know whether these standards have been updated and improved on since the facility was designed and constructed? Have you assessed these improvements and considered whether they are relevant to your current operation? Are you continually looking for ways that your operation can be improved?

Reflekt AS