We’ve had a number of questions asked by local residents who are interested in understanding what potential impact, if any, the hydro may have on local flooding. With the help of the Environment Agency, we have put together the following information which we hope will reassure our neighbours, and help shed light on how local waterways are managed.
Does the installation of the second hydro at Osney Lock increase the risk of flooding?
No. The hydro required the Environment Agency’s permission to operate. This would not have been granted if the hydro posed any additional risk to flooding. The Environment Agency (EA) was closely involved in the project throughout the design and construction phase, and has worked closely with the hydro team to integrate the scheme into its waterways management systems.
Has the installation of the hydro resulted in a narrowing of the channel or reduction in flow capacity?
No. The width of new weir B (the weir situated in the same channel as the hydro) is the same width as the original weir gate. The channel was widened to accommodate the hydro. There is no reduction in flow capacity through the weir. The addition of the hydro and fish pass, along with the change in design of the weir gate have actually resulted in an increased flow capacity at that point. This is why Weir A (under the footbridge) is now so rarely in use.
What happens if the hydro stops or the hydro channel becomes blocked?
It is typical for river levels to initially rise quickly in response to changes in flow. Weir overspill then comes into play, and slows the rate of rise. Waterways management is entirely under the control of the EA. When river level rises occur, the EA can increase the flow over Weir B and Weir A as part of the normal operation of flow management to accommodate this change. As part of their role, the EA monitor the river’s response to rainfall and are ready to warn residents if levels pose a flood risk. There is a monitoring and alarm system in place that contacts duty staff should the river rise to at preset alarm levels. The EA plan to automate Weir B in 2016 which will reduce the effect of changing flows on the river levels and reduce the need to call out staff after hours.
How much electricity does the hydro generate?
In an average year it is expected to generate 179,000 kWh. This is equivalent to the power used by more than 50 homes. Generation fluctuates with river flow, such that it may not generate at all (as we saw this summer) or produce over 1000 kWh in a single day (as achieved several days this autumn.) That’s sufficient to make 50,000 cups of tea. The main generating period is during the winter. We will post regular updates of generation on our website and at the hydro so you can see how we are doing.
What community benefit does it generate?
Over its 40-year lifetime the hydro is expected to result in £2 million worth of community benefit. However, during the first few years of operation, the amount available for community benefit will be fairly modest as we need to repay short term loans and recover the costs associated with the construction of the fish pass. In the financial year 2016/17 we hope to donate £15,000 to local environmental projects.
What other plans do you have for the hydro site?
In the first instance we want to finish the hard landscaping and complete the balustrading at the site so we can safely open the site up to the public. In our last survey to residents, concerns were raised about the risk of attracting antisocial behaviour if the site were to be left permanently accessible. With this in mind, we will be trialing restricting opening to daylight hours. We have also been consulting with local residents, community groups, schools and other key stakeholders to learn how we can use the hydro as an opportunity for people to learn about the story of our river – from enhancing understanding of local waterways management to exploring our community’s rich industrial and social heritage.
If you have any questions relating to Osney Lock Hydro, you can contact the team via the contact page on our website. And we would be delighted to meet with anyone interested in learning more about the project for a chat or would like a guided tour with one of our volunteer guides.