The topography and geology of the Calder Valley renders it susceptible to flooding, compacted subsoils overlying impermeable clays soils result in rapid run off during extended periods of rainfall which is funnelled quickly to the valley floor through an extensive system of headwater streams and old culverts built to supply water to the mills in the valley.
The problem has been exacerbated in the last few centuries by the growth in
population, developing industry and house building and along with the increasing
effects of climate change, the risk of flooding now is greater than ever all along our
In the spring of 2018 Source Partnership members Treesponsibility, South Pennine
Facilitation Group and Slow The Flow came together to develop the Calderdale
Council NFM Grant Scheme. This pioneering scheme was designed to fund Natural
Flood Management projects in Calderdale using the expertise of local engineers and
land managers in partnership with willing local landowners.
One of the projects that was identified was Shoebroad Dam in Todmorden. This was
a neglected former mill pond that had overtopped during the Boxing Day flood of
2015 and now presented itself as a hazard to Todmorden. This is one of the many
mill ponds that have become redundant and neglected identified by Slow The Flow
and that might be viable assets if brought back into use.
The History of Shoebroad Dam
The dam was constructed in the 1830’s by the Fielden brothers (1) around the same
time as the larger Gaddings Dam (1834-35) and was used to power the steam
engine at Waterside Mill which once housed the largest weaving shed in the world.
It was located where Morrison’s Supermarket is now situated so its proximity to the
centre of Todmorden is a critical factor in having the opportunity to protect
Todmorden from flood risk using this sizable dam.
The pond had lain abandoned for two generations, with Waterside Mill closing in
1961 and then later demolished in the 1980s. There was an old disused and
redundant valve which would have allowed the pond to be completely emptied and
cleaned out which was defunct. It had a narrow spillway opening for some reason
unknown which probably caused it to over top on Boxing Day 2015. The overtopping
had damaged the dam and there was evidence of landslip present.
The pond had silted up with up to 1.5 metres of it in the bottom. It was unsafe and
posed a threat to Todmorden in the event of a major flood event. The dam was also
overtopping during Storm Ciara in February 2020 as a pump in place to keep the
water purposely low could not keep up with the inflows.
Following the work of the Source Partnership the opportunity to use Shoebroad Dam
as an attenuation feature for Todmorden was recognised and work began to assess its suitability to store storm water. There were many bureaucratic challenges along the way but in May 2020, the work was finally finished. You can see more here on the pictorial blog on Shoebroad Dam on how the dam was constructed.
What was the process to renovate this historical feature?
Firstly, contractors removed as much silt as possible from the pond, depositing it in a
pit known as a ‘borrow pit’ in an adjacent field using the clay removed from the
borrow pit to widen, strengthen and repair the damaged earth dam.
Water flow was then redirected into it from a channel that ran right past it, to increase
it’s utility value.
A low level pipe was added to maintain just a small amount of water in the dam to
maintain wildlife, the remaining volume being available for storm water. The spillway
was modified back to its original width allowing the dam to overspill safely.
So the dam will no longer fill under normal conditions but it will fill in a flood condition
safely, emptying slowly via the low level pipe but in the event of a really big flood the
water will over top over the widened spillway and discharge safely to the stream
The project was completed at a cost of £35,000 in six weeks using a local contractor
and a local civil engineer, the pond can store up to 3.2 million litres of flood water.
This is an example of a low carbon project that provides flood protection with no
disruption to traffic and by creating a permanent pond environment can sequester
carbon in the future. http://slowtheflow.net/slowing-the-flow-and-carbon-reduction-through-floodwater-storage/
What can you to do slow the flow?
The success of the rejuvenation of Shoebroad Dam from a liability to a valuable
asset in the form of a flood attenuation pond offering protection to Todmorden from
increasing flood risk has been replicated across the catchment with many other NFM
schemes now in place via the Calderdale NFM Grant Scheme. They include 17
attenuation ponds, 1000s of new trees planted and our own scheme at Hardcastle
Crags building over 600 leaky woody dams.
More schemes are planned but we need to identify many more additional
opportunities to manage the flow of water in the uplands to slow the flow into the
valley where the majority of the population live and work.
If we can do this, it means that the hard-engineered schemes in the valley can work
more effectively to prevent flood risk.
If you have land, however small, and would like to discuss how you too can
contribute to reducing flood risk in Calderdale, please use this link here to tell us
Other blogs on some of the other schemes in Calderdale can also be found here.