Ongoing maintenance
Welcome to our maintenance page. Here we will keep you informed of any work being carried out by our teams on the Lower Mole. We will update this page with more information and photographs of any works we are carrying out as the work progresses. You can also view any information that has previously been sent about our maintenance works to residents here.
Should you require a more accessible version or a paper copy please contact us at fasproject.lowermole@environment-agency.gov.uk. We want to be as accessible as possible but also mindful of the environment, so please consider whether a paper copy is best option before you make your request.
November 2024 maintenance work.
We need to inspect all the underwater assets to make sure they are all in working order. As part of these inspections it will be necessary to lower the water level upstream of Molember Sluice, This may last up to 14 days depending on the progress of our work We carry out this work every 5 years additionally, we may need to do it for the following reasons:
- The riverbed downstream of Island Barn Sluice has experienced some erosion following recent higher flows. This inspection will allow us to take a more detailed look and will allow us to design the repairs.
- There are a number of areas where the riverbanks have eroded below the waterline. The banks include our track we use for access to maintain the channel and in a number of areas are part of the ‘raised defences’ protecting properties. This inspection will allow comparison to their condition 5 years ago so we can determine the priority for any works.
- Our contractors Volker Stevin are working on the sluices to make repairs to a number of gates that are not working and to install improved eel passage arrangements. Lowering the river reduces risks to their staff working in the channel.
- We need to inspect the ground anchors of the sheet piles that support the banks along Molember and Summer Road.
- We need to inspect all the access and egress ladders.
- To inspect the surface water outfalls that enter the River Ember in this reach to see if their flap valves are present and in good working order.
- Thames Water are proposing to construct a new 1400mm diameter new outfall from Island Barn Reservoir to the River Ember as part of their reservoir safety actions. We need to do a condition survey with them prior to their works commencing.
What will the river look like during the work?
The depth of water will drop considerably as we gradually open the gates at Molember Sluice. This will not affect the flow. The river is being slowly lowered over a day to minimise risks to the fish and wildlife. One of the radial gates will then be left open to allow migration of fish and eels.
What about risks to the environment and wildlife?
The work has been planned for this time of year following advice from our Fisheries, Biodiversity and Geomorphology team as its cooler and we are outside of fish spawning and bird nesting periods. We will check the river on a daily basis to monitor the effects on wildlife.
What if the river levels need to be changed?
By only lowering the one reach, should there be a need to restore levels along this section of the river we can close the gates at Molember sluice and lower the gates on the sluice structures upstream to raise river levels within approximately one hour. We will also be installing a sandbag wall to avoid reducing levels in the Ember Court loop too quickly.
What about Flood risk?
By lowering the river, we will be reducing flood risk as there will be more capacity available within the engineered channel should flows increase. If heavy rainfall is forecast the programme will be reviewed and the inspections potentially postponed for a few days until flows within the river reduce again.
February 2024 recovery works update
Maintaining our structures
The Molember, Island Barn, and Viaduct sluices are positioned along the Ember channel. Most of the time, we would keep the gates closed to maintain the water levels. During wet weather periods, we open the gates to prevent flooding. As the structures get older, we need to do maintenance works to ensure they maintain water levels. We will carry out these works whilst the future Flood Alleviation Scheme (the Scheme) is being looked at.
Our planned recovery works are designed to comprehensively address various aspects, ensuring we can use the weirs to effectively control the flow of water. This includes replacing wire ropes that help to move the sluice gates up and down, fixing gates that have broken and repairing mechanical components. To modernise the way, we operate the gates we will install new control panels at each weir site. These panels will play a pivotal role in ensuring seamless communication between the working gates and our operators.
Currently at Molember, one radial gate has broken, and wire ropes need replacing. At Island Barn, we recently fixed one radial gate and one tilting gate and replaced the wire ropes. At Viaduct we need to replace the wire ropes.
Our works will be taking place on the following dates at each structure. Please be aware this could be subject to change; works could be extended until Summer 2025:
Spa Meadow (our site compound) February 2024 - March 2025
Viaduct Weir March 2024 - July 2024
Island Barn June 2024 - October 2024
Molember September 2024 - January 2025
Royal Mills September 2024 - February 2025
During this time, we aim to keep disruptions to a minimum, however plant and machinery will be moving from our depot at Spa Meadow along the partly public accessible access track that runs along the Ember Channel. We apologise for any inconvenience this may cause and thank you for your cooperation and understanding during this period.
Improving the environment and infrastructure
As well as the structure maintenance, we are looking to enhance the Scheme this financial year. Our multifaceted works focus on improving health and safety, security, and the environmental aspects of the Scheme. We are committed improving operational efficiency of the Scheme and the safety of the surrounding community. We acknowledge and appreciate your understanding and cooperation as we embark on these initiatives, collectively striving to create a more resilient and secure environment for all. You can find out more about environment enhancements on our 'improving the environment on the Lower Mole page'.
Bridge enhancements
Several bridges along the Scheme, both public and private, are scheduled for vital improvements. Please see figures 1 and 2, below. During comprehensive bridge inspections last year, we identified the works required for ensuring the safety of both operatives and the public. As critical access points for our teams to reach different weirs, these bridges play a pivotal role in the scheme's operational success. The works aim to address minor defects, thereby enhancing safety for all users of the bridges and surrounding tracks. The two maps below show the locations of the bridges.
Figure 1 – Bridges requiring improvements located on the River Ember (Copyright Google 2023)
Figure 2 - Bridges requiring improvements located on the River Mole (Copyright Google 2023)
Security upgrades
The security of our flood structures along the Rivers Mole and Ember is important. Damage to the structures could result in flooding. We need to ensure they are not accessed by members of the public to avoid any damage and for health and safety reasons. We will be updating security at our sites which includes replacing any worn fencing and installing new access gates in select locations. For further information, see our 'safety and security frequently asked questions page'.
Eel Pass Project
After a component failure on Zenith Weir led to the removal of the previous eel pass, a temporary rope pass was installed in compliance with the 2009 Eel regulations. We are now launching a new and improved eel pass project. The objective is to create a permanent eel pass structure, ensuring the safe and unimpeded passage of eels over the fixed weir. This initiative aligns with our dedication to environmental stewardship and compliance with regulations, promoting the well-being of aquatic life within the waterways. We would remove the weirs as part of the pink and orange options. As a result, many fish and eel passes would not be required at various location along the Scheme. You can find more information about different environmental projects on our 'improving the environment on the Lower Mole page'.
Pennywort maintenance
To see how we manage Pennywort on the River Mole please see our 'environment frequently asked questions page'.