Work on the Morpeth Flood Alleviation Scheme is entering its final stages. Environment Agency Project Manager Anthony Myatt reports on what has been completed so far, and what there still is to do.
Morpeth Town Centre (1)
The new and upgraded flood defences in the town will protect it from a one-in-50-year flood — or one with a two per cent chance of happening in any year. All of the town centre defences in the main alleviation scheme are now built, but final small jobs and tidying-up is ongoing.
High Stanners (2)
Mr Myatt said: “This was a particularly challenging area for developing the design. In the past with flood schemes that have been put forward, the constant challenge has been the need for large structures, such as high walls.
“High Stanners is a very important public space and people want accessibility to the riverside so working with the community and looking at the options, we came up with a combination of walls and floodgates and an embankment to give the feeling of access to the river.”
The flood wall and floodgates are now complete and watertight. However, repairs are needed to one of the floodgates after it was damaged. The problem does not affect the operation of the gate, but materials for the work are not due to arrive until Easter.
A soakaway has been created on the riverside near Oldgate Bridge to resolve a drainage issue. It will be monitored over the coming months and further work will be carried out if necessary.
The Environment Agency is also monitoring the embankment to make sure that grass seed is taking.
Meanwhile, branches have been removed from trees closest to the River Wansbeck as part of a regular maintenance programme to try to reduce the amount of debris in the river that could cause obstruction.
Mr Myatt added: “The delivery of the work in this area has been quite challenging. The constant challenge has been finding the location of unidentified services, which led to significant delays, but the team has continued to deal with that challenge and has delivered a high quality product that fits in with this area of Morpeth.”
Mr Myatt said: “This was more challenging in some ways than the upstream storage area because we had to construct walls through 24 or 25 back gardens.
“The Environment Agency took the approach to have negotiations with each of the residents, discussing options for the walls and the final design of the gardens to minimise the impact of the works on them and their properties.
“We did come up with some challenges, such as unidentified services and access issues, but we have come to a completion on that piece of work and I would hope that the residents are pleased with the outcome.
“We are certainly happy with how the finished product looks.”
St Robert’s Church, Oldgate (3)
Discrete flood defences have been built close to the church.
Mr Myatt said: “A significant amount of work has gone into constructing the foundations.
“We were constantly changing the foundations of walls through the town to a size that would allow higher walls to be constructed. We have tried to make the flood defences as unobtrusive as we could.”
Pretoria Avenue (4)
Mr Myatt said: “In this area the works ended up being a lot larger than first intended.
“When we investigated the existing defences we didn’t feel they were up to standard when compared to the latest construction techniques and the standard of the new defences.
“It was so marked that we decided to take down all the old defences and install a new scheme of defences to the current standards.
“There was quite a lot of disruption to the residents, definitely for parking. We had to make sure that we maintained access and delivered a quality product at the end.”
The Chantry (5)
Flood walls have been built to fit the character of the historic building and The Chantry garden has been re-modelled.
Mr Myatt said: “This is a very significant building in Morpeth and it is the gateway to the town. We looked to ensure that our design was in keeping with that environment. We worked with landscape architects to deliver a scheme that would protect that beautiful area and also make it a bit special for people.”
St George’s United Reformed Church (6)
A new flood wall, clad with natural stone, has been built, and access ramps are being reinstated. A landscape contractor will complete the restoration of the garden at the church and plant flower beds in the car park.
Mr Myatt said: “This was a similar situation to The Chantry. We had to demolish an old defence and reconstruct it in natural stone so that it was in keeping with the local area.
“We reconstructed a flood wall along The Terrace car park and clad the river side of the wall with natural stone. It makes it more attractive when looking over from the other side of the river.”
Low Stanners and Middle Greens (7)
Mr Myatt said: “This area was planned to have significant reconstruction of existing flood walls, but when we carried out some survey work and site investigation we found that the existing wall was the right height that was needed to defend the town and in line with other defences.
“We have reconstructed a ramped system at Stobs Ford and reconstructed the wall through Middle Greens allotments because some sections of the wall had become eroded over time. We are completing the reinstatement of the allotments to quite a high standard.”
Upstream storage at Mitford (8)
Work is ongoing to bring the upstream floodwater storage area at Mitford into operation.
Once in place and combined with town centre defences, it will protect Morpeth from a 1-in-137-year flood — one with a 0.7 per cent chance of happening in any year.
The main dam structure and clay embankment is now complete, but progress has been hampered due to wet ground conditions.
Work on access roads, drainage and some earthworks, including finishing the spillway and completing top-soiling of the dam, will be re-started when conditions allow.
The team is continuing to install equipment that will control the flow of water when the dam is operational, and testing and commissioning of the penstock gates will be done as soon as possible.
Mr Myatt said: “The dam works by channelling the Wansbeck through a system of six culverts. The flow of the Wansbeck is controlled by a series of penstocks. In the event of water levels increasing, the water is held back to limit the amount that flows downstream.
“Due to the bad weather we had towards the end of last year, we were unable to complete the work as intended for the end of December. The risk of churning up the embankment that was completed was too great and could have perhaps caused more work going forward.
“We now envisage the completion of the structure by the end of April, but that is subject to conditions.”
The Cotting Burn
An upstream floodwater storage system is also being designed for the Cotting Burn.
Initial preparations will soon be carried out, including pruning and removal of trees.
“A contractor is to be appointed, materials ordered and work plans formed, with construction expected to start in the summer. It is scheduled to take three or four months.
Meanwhile, lockable covers have been fitted to two manholes on the burn to prevent water escaping during a flood. However, further surveys are needed for the same upgrade to a manhole at Copper Chare due to its proximity to building foundations.
Mr Myatt said: “We are about to go to tender for the Cotting Burn upstream storage area.
“We are in the process of consulting with residents, sorting out tree clearance, and getting ourselves ready for that work to be completed.
“The purpose of this structure is to keep water upstream of the culvert system through the Cotting Burn, which historically has flooded severely.
“We have tried to minimise the risk of that situation by putting lockdown covers on existing manholes, but this structure is to keep water back and also manage debris.
“There have been a lot of problems in the past with trees getting into the culvert system and causing blockages. We thought it was important to try to tackle that and keep it away from the town as best we can.”
A system is being designed to restrict the flow from the Wansbeck into the Leat.
However, further investigations are needed to ensure that listed buildings will not be affected.
Once the main upstream storage area at Mitford and the work at Abbey Mills is complete, nine vertical tree poles will be placed across the river upstream of Lowford Bridge to catch large debris, such as trees and branches, before they reach Morpeth and potentially block bridges.