The partial collapse of the concrete spillway at Toddbrook reservoir, Whaley Bridge, has been deemed “catastrophic”, with approximately 1,500 of the town’s residents having had to be evacuated while engineers pumped water from the reservoir to prevent the dam from further collapse.
While residents have since returned to their homes and normality has – almost – resumed, the events at Whaley Bridge are a reminder of the vulnerability of some of the nation’s older infrastructure and its ability to cope with modern day pressure points, including climate change and population growth.
In England, reservoirs capable of holding 25,000m cubic metres or more of water are regulated under the Reservoirs Act. Where a reservoir is deemed to be “high risk” (a danger to human life), the Reservoirs Act allocates responsibility for safety to a reservoir undertaker. This individual or individuals can be the owner, operator or a nominated representative of a group of owners or company.
Among its obligations under the act, the reservoir undertaker has a duty to maintain the reservoir to ensure its safety under a number of loading regimes, and to have the dam inspected periodically by qualified civil engineers. These inspections take place every ten years and should make any recommendations to make further provision against escapes of water, should any issues be uncovered.
But following an inspection at Whaley Bridge in November 2018, which gave the dam a clean bill of health with no recommendations made in the interest of reservoir safety, questions should be raised around whether these inspections are sufficient when it comes to dealing with our ageing infrastructure.
In the 1800s when many of the country’s reservoirs were built, their function wasn’t to provide flood alleviation, but mainly to supply water in that area.
The role of dams and reservoirs within our ecosystem has shifted and the pressure is on to ensure companies have the funding available to improve the resilience of UK infrastructure. In PR19 Ofwat announced an additional £12 billion of spending above business-as-usual costs to increase the resilience and safety of utility projects. This is crucial, particularly as flooding is expected to become more commonplace.
Spells of extreme weather are increasing in frequency. The Environment Agency has warned that the country’s infrastructure will need to adapt to cope with an increase in global temperature of 4C by 2100. This, coupled with demands from a growing population and the increase in other infrastructure such as roads close to dams as a result, means criteria around the safety of ageing reservoir infrastructure should be revised to account for such factors.
Currently, the Reservoirs Act does not require a review of the standard of a reservoir’s infrastructure. Yet over time, findings from industry research, recommendations or changes in best practice guidelines may make adjustments desirable so a reservoir’s infrastructure remains as robust as possible. Ongoing supervision and inspections are paramount in ensuring dams and reservoirs are up to scratch.
As events at Whaley Bridge have shown us, the timescale and costs associated with the clean-up and rebuilding of a community are significant, not to mention the impact it has on people’s livelihoods. While not currently a legal requirement, reservoir undertakers must ensure plans are in place to control or mitigate the effects of flooding. These plans should be specific to each reservoir and shared with the local authority. The Environment Agency also has a responsibility to ensure reservoir undertakers do not delay safety work on reservoir infrastructure and that such work, where recommended, is prioritised and implemented.
The flooding issues we’ve seen at Toddbrook Reservoir are unlikely to go away anytime soon and threats to other areas of infrastructure are very real. The challenges associated with climate change and a growing population demonstrate that now is the time to identify solutions to ensure we’re able to cope with increased flood risk. The regulator’s latest PR19 review is encouraging, but all parties – local government, utility companies and the Environment Agency – have a part to play in minimising future risk.