Geoff Jones

Inveterate dabbler in business, travel, gadgets & life

Whaley Bridge 147 years of floods!

Damage to overflowInteresting to find a couple of old reports on ‘freak weather’ in Whaley Bridge 147 years ago.

Whaley Bridge is mentioned twice in the flood chronologies for events in June 1872 and July 1881:

On 19th [June 1872] the Goyt was 12 to 14 feet above its normal level. At Whaley Bridge houses near the river were completely flooded and people were taken into the chapel and inns … in Macclesfield a woman and child were drowned when the river Bollin overflowed. Two reservoirs burst in the vicinity.
From: https://theconversation.com/heatwaves-and-flash-floods-yes-this-is-britains-new-normal-121351

The summer of 1872 was a wet and exceptionally thundery summer with frequent and at times severe thunderstorms.

Some reports of the thunderstorms that occurred during that summer.

18th June 1872

Chesterfield: Severe thunderstorm at night

Macclesfield: Thunderstorm lasting 12 hours.

From https://www.netweather.tv/forum/topic/62652-the-very-thundery-summer-of-1872/

Still, we managed a quick ride from Buxton down The Goyt after a couple of very very wet days with the overflow at the Errwood Reservoir in full flow

Update 5 Aug 2019

December 1964

Toddbrook Incident date: December 1964 Construction details The reservoir was constructed in 1840-41 to supply water to the Peak Forest canal. It is on the north-west edge of the Peak District National Park near Whaley Bridge. The embankment is 24 m high with 1:2 upstream and downstream slopes. Further details of the dam construction are given in Incident No. 23. Incident description The water level was one metre above the spillway crest for a period of 24 hours following heavy rain and it took another two days for the level to fall to normal top water level. Damage was caused to the lower part of the spillway channel. Some parts of the side walls were washed out and some erosion took place on the right bank adjacent to the downstream toe of the dam.The main deterioration was caused by excessive flow down the spillway. Response The 1964 flood damage was repaired in 1965 and subsequent flood studies confirm the spillway was inadequate to take the design flood. An additional spillway was built in 1969 with a 75-m weir built over the southern section of the embankment discharging over a concrete-protected portion of the downstream face. The sill level is above the original spillweir level. Lessons The incident showed that despite the dam being in existence since 1840, the spillway was inadequate. The incident instigated a flood study of the reservoir resulting in an additional spillway constructed.

Charles, J Andrew; Tedd, Paul; Warren, Alan. “Delivering Benefits Through Evidence Lessons from Historical Dam Incidents”. environment-agency.gov.uk. Environment Agency. p. 140. Retrieved 1 August 2019.

CHARLES J A (1986). The significance of problems and remedial works at British earth dams.
Proceedings of BNCOLD/IWES Conference on Reservoirs 1986, Edinburgh

From: https://obiterj.blogspot.com/2019/08/emergency-at-toddbrook-rservoir-whaley.html

22. Toddbrook
1977
Construction details
The 24-m high dam consists mainly of boulder clay with sands and
gravels. There is doubt about the existence of a puddle clay core even though it is shown on the original construction drawings. The dam is founded on fluvio-glacial sand and gravels, glacial till overlying a faulted sequence of mudstones, sandstones and shales of the Millstone Grit Series and Lower Coal Measures.
Incident history
The dam has a history of leakage. Since 1880, there were complaints about leakage into mine workings. In 1930 leakage was observed at the toe of the downstream slope. As a result of an investigation into the leakage, a depression was found on the upstream slope. This was investigated in 1931 and the area was then reinstated.
Incident description In November 1975 when the reservoir was low, a depression was noted in the same position on the upstream face as the 1931 depression. In Autumn 1977, 120 mm of subsidence was measured since 1975. The reservoir was emptied to inspect the full extent of the depression and revealed a crater approximately four metres across at the upstream toe partly in filled with silt and into which a tree appeared to have been sucked.
Investigations
Extensive investigation included boreholes, sampling and piezometers. Exploratory shafts were sunk on the upstream and downstream faces between 1978 and 1980. In 1981, a 1.2-m diameter masonry culvert was found beneath the dam, possibly for stream diversion during construction. Tracer tests showed this to have formed a leakage path through the dam.
Remedial works
In 1981, a compacted clay blanket was placed over the suspect area of the upstream toe and the bed of the reservoir. To solve the leakage problem, a single row grout curtain 60 m long within the clay core was formed using the tube-à-manchette system. The reservoir was refilled in December 1983.
Lessons
Until the reservoir was drawn down, the extent of the crater caused by erosion was unknown. The good practice of periodic inspection of the upstream face of a dam is illustrated by this incident.
Spillway in 2016

Left is an interesting video from Miles Haslam showing the spillway in August 2016 with a small tree growing in it at the point that recently failed ! and on the right with a photo during the recent overflow showing the same tree 3 years later!

Post Views (>151116): 816

Reader Comments

Comments are closed.