SRA End of Year Report 2017-18: Dredging & River Management (W1)
West Somerset Streams
A high proportion of watercourses in West Somerset are classified as ‘Rapid Response Catchments’ and ‘High Risk’ rivers – ‘High Risk’ means people could die in times of flood. Where watercourses can fill up and flow dangerously quickly when it rains, it is important to maintain their capacity to convey and discharge safely as much flood water as possible. SRA funding enables extra maintenance to be delivered by the Environment Agency.
Achieved: 1) Carhampton – A39 bridge/ culvert: cleared of five tonnes of silt and gravel downstream. Vegetation was also cleared from about 200m of watercourse downstream of the A39. Both activities followed on from SRA- funded clearance works in Carhampton in 2016- 17.
2) Minehead – Parkhouse Lane, Minehead: Culvert cleared to improve the conveyance capacity of the Bratton Stream. Plus: The final stage of works on the Bratton Stream through The Parks in Minehead, funded by the SRA in 2016-17, was also completed. It had been deferred from spring 2017 to allow for fish spawning. Most of Minehead lies within the floodplain of the Bratton Stream and its tributaries. About a third of the properties in the town and nearly all of its businesses are at high risk of surface water flooding.
Being Achieved: Near Gallox Bridge, Dunster. A project joint-funded by the SRA and the Environment Agency, delivered by the Environment Agency using contractors Land & Water. Its aim is to prevent the erosion of a 35-metre stretch of bank, by putting in a ‘rock roll’ system, and thereby in turn protect an access track and the main River Avill flood bank. Site investigations included an ecology survey, the use of ground-penetrating radar and a topographical level survey. A detailed design was completed and work began – but matters were delayed by the unexpected discovery of asbestos piping, of uncertain origin. Its removal required specialists. Work was completed in April 2018.
West Sedgemoor and Aller Moor Viewed Rhynes
Previous funding regimes restricted maintenance on these moors mostly to every other year. Extra, SRA-funded annual maintenance ensures that drainage channels can convey flood water to Main Rivers and pumping stations. This helps to protect local homes and businesses, local roads and 650 metres of the A378 at Wrantage. It also enables seasonal water level management in accordance with Water Level Management Plans and it reduces the likelihood of summer flooding, which can be particularly damaging to farmers and wildlife. Achieved: Just under 30,000 metres of additional channel maintenance (weed clearance and sediment removal) was delivered by the Parrett IDB for the SRA on West Sedgemoor and Aller Moor.
Sedgemoor District Council flood relief and drainage assets
Additional SRA funding gives Sedgemoor DC greater capacity to deal with issues before they become problems and to put in enhancements, such as telemetry, that make flood defence schemes and infrastructure more efficient. Being achieved: CCTV surveys were done in North Newton, Cheddar and Wedmore to identify problems and allow preventative maintenance to be planned. Further CCTV work will be done using funds carried forward to 2018-19, to help ascertain conditions and plan more repairs. Achieved: Carried forward from 2016-17. In summer 2017, telemetry equipment was installed at Blake Gardens, Bridgwater and Bays Pond, Cheddar. Real-time data will help flow regulation and barrier deployment.
Brue Tree Work
Throughout the Brue valley catchment, water is collected and distributed via rhynes, drains and channels, so as to obtain desired levels. The main artery of this water management system is the River Brue. This project increases the capacity of parts of the Brue to carry water. Originally part of the SRA’s Enhanced Maintenance Programme for 2015- 16; delayed for environmental reasons.
Being achieved: As the Brue is a Main River, a Public Sector Co-operation Agreement between Somerset Drainage Boards Consortium (SDBC) and the Environment Agency, enabled SDBC to deliver this activity for the SRA. SDBC – with contractors WM Longreach – carried out 1.3km of tree work between the A38 road bridge at Highbridge and Hackness Sluice. Increasing flow in these lower reaches of the Brue will allow water to evacuate faster at times when there is a risk of flooding.
Work involved the selective removal of trees, branches and scrub vegetation using pole- saws and chainsaws operated from a floating, tugboat-propelled pontoon. Because of the environmental sensitivity of the area, a ‘light- touch’ approach was taken. Ecologists oversaw the work, so as to ensure protection for water voles, otters, kingfishers and other birds.
Felling, pruning and scrub-removing was only carried out where trees, branches or vegetation were judged to significantly impede high level flows. Further carefully targeted maintenance work upstream of Hackness Sluice is planned for autumn 2018, then more in 2019-20.
Pumping Station Repairs and Improvements
SRA funding enables extra resilience, security and efficiency at permanent pumping stations. It means the Environment Agency can better protect people, homes, businesses and land.
Westonzoyland Pumping Station
Being achieved: 1) SRA funding is being used by the Environment Agency to develop plans to automate Westonzoyland Pumping Station.
Plans involve replacing the current single pump – powered by a 1990s’ lorry engine – with a more efficient and powerful electrical canister pump (like that used at Screech Owl) and a supplemetary pump for use when need be. Automation would enable better use of Environment Agency staff time: for example, no worker would have to be sent out to Westonzoyland to get the old engine going and then later turn it off. Preparations have included a topographical survey and the production of an Options Appraisal that includes costings and a detailed outline design. A Final Report will inform the business case for the work and budgetary requirements for 2018-19. A bid to the SRA is expected in 2019-20 for funding for an automated trash screen (like that coming at West Sedgemoor – see below).
West Sedgemoor Pumping Station
2) The Environment Agency is using SRA funding to develop plans at West Sedgemoor Pumping Station for a new trash screen that can be cleared automatically. Such a screen protects pump equipment, by stopping material being sucked into the pumping mechanism. Preventing blockages also reduces flood risk locally by stopping water backing up. Work has so far included a detailed study of the West Sedgemoor compound to work out the best ways of carting off the soggy heaps of material that a screen is expected to catch. As access is tight, it is crucial that the drivers of skip lorries and trailers have enough space to manoeuvre and turn their vehicles round. Trials have been run, and a model layout prepared, with encouraging results. The scheme will therefore progress in 2018-19.
North Drain Pumping Station
Carried forward from 2016-17 – Being achieved: A design and construction plan has been completed for roof repairs at North Drain Pumping Station but work has been delayed to minimise the impact on roosting bats. As bats are legally protected, mitigation measures have also been taken: for example, new bat boxes were put up in 2017. Roof repairs due to start May 2018. Not yet achieved: Saltmoor Pumping Station – roof repairs, possibly combined with lifting-out of old pump when roof is off. Work delayed by complications to do with asbestos, Listed Building status and cost.
South Somerset Enhanced Maintenance
SRA funding enables smaller schemes that deal with local issues in a pro-active way that makes flood alleviation schemes work with extra effectiveness. Some unspent funding was carried forward from 2016-17. Achieved: Enhanced maintenance to repair bank erosion on Merriott’s flood attenuation dam, upstream of Moorland Road.
Main River Asset Improvements
The Environment Agency has many assets in Somerset; bids for national funding fall short of what is needed to maintain and improve them all. SRA funding enables stronger action to be taken against flooding and potential flooding.
Being achieved: 1) Frome. Repairs to part of Frome’s Flood Defence Scheme, which protects 300 properties. The focus has been on the River Frome’s revetment: that is the fortified layer which protects earthen river banks – and the properties and the roads behind those banks – from erosion, especially on bends where this shield is pressed hardest during times of high flow.
A design and build contract was awarded in September 2017 to contractors Land & Water by the Environment Agency, which is delivering this scheme for the SRA. Minor vegetation works have been done, and banks surveyed to establish priority areas.
Extensive consultation has included talks with Frome Town Council, Mendip District Council, Wessex Water, Network Rail and local community groups.
Work has begun on a detailed design which reflects input from all of these interested parties. It is focused on strengthening the ‘toe’ of the revetment in particularly problematic areas and on improving the condition of the outfalls that spill over different sections of the revetment.
Ecological considerations have also been important. For example, the coarse fish spawning season (March 15th – June 15th) ruled out construction then. Works are therefore due to start in the second half of June.
Being achieved: 2) Huntworth, near Bridgwater – Carried forward from 2016-17. Delivered for the SRA by the Environment Agency. A new electric canister pump was installed in autumn 2017 at the Screech Owl outfall near Huntworth, close to Bridgwater. It is operational. It was used over the winter and early spring to remove excess floodwater from around The Boat & Anchor Inn and from along Marsh Lane by the Huntworth Business Park (which includes an Argos distribution centre and The Canalside conference centre).
Not installed (as at 31 March, 2018) was a supporting hydrometry and telemetry station at The Boat & Anchor to provide information about local flood levels and (if need be) remotely trigger the pump into action. Permission from the Canal & River Trust was required to put equipment on land owned by the Trust. It is due to be installed by the end of June 2018.
The whole scheme is also tied-in with the SRA- funded de-silting of Huntworth Brook, which feeds into the Screech Owl outfall.
Maintaining Resilience of Wet Grassland
This project is investigating how water levels and land can be managed to enable flood- resilient farming and good environmental outcomes in flood-prone areas for the next 20 to 30 years. Work began as part of the SRA’s 2016-17 Enhanced Programme, and more funding was given for 2017-18. The Parrett IDB is leading the project for the SRA, working closely with Natural England.
Being achieved: After five initial visits to landowners in 2016-17, exploratory work continued with visits to seven more landowners in West Moor SSSI, south of Langport at the River Isle/River Parrett junction. The aim has been to find out more about people’s individual approaches to farming and to discuss their environmental grants. Grassland condition surveys, which began in February 2017, continued until July 2017; bird surveys were carried out from April to June 2017. Information gathered is being used to help assess current water level management arrangements, so as to establish issues of concern and identify possible improvements.
Opportunities for collaborative working are also being explored, as this wet grassland resilience project may fit in very neatly with the Levels Land Trust work outlined on pages 26-27. Since January 2018, therefore, Will Barnard from Pawlett Hams has been consulting West Moor landowners again, getting their views about the idea of a ‘moor association’ and their thoughts and feelings in general about farming on the moor. He has also been consulting graziers.
Once people involved have agreed a way forward, talk will turn more specifically to how engineering works could bring benefits to both farmers and wildlife. Such works could include better maintenance of existing water level management control features or the design and installation of new equipment.
After a public consultation about the possibility of ring banks for Moorland, Chadmead and Fordgate in 2015, which revealed significant opposition in Fordgate to the idea, the SRA Board commissioned further work in Chadmead and Moorland. The aim was to see whether residents – given more information – could reach a consensus, either for or against. Consensus is important because a ring bank protectively circling people’s homes has to be an ‘all or nothing’ job. No gaps can be left because water could flow through those gaps and the ring bank would not work. As there was more initial consensus in Chadmead, a draft technical report was prepared by the Parrett IDB, suggesting three possible design options. Being achieved: Two meetings were held in August 2017 with local people, so they could decide for themselves what (if any) progress was desirable. Feedback from the meetings was encouraging. Property owners therefore agreed that a detailed survey should be carried out on their land in April 2018. This will enable the preparation of a technically sound ring bank design. Local people will be consulted about this design and if everyone supports the idea of a ring bank actually being built, attention will turn to how its construction and maintenance could be funded.
Step change in encouraging and enforcing riparian work
After the 2013-14 floods, it was widely felt in Somerset that problems were exacerbated because too few riparian owners knew and carried out their responsibilities, particularly for maintenance. There was a need to be more pro-active.
Who is a riparian owner? A riparian owner is somebody who has any sort of watercourse (including a main river) on or under their property, or next to any boundary of their property – unless that watercourse is known to be owned by someone else. Ownership of watercourses along boundaries extends to the centre of those watercourses.
In Somerset, the Environment Agency will continue to deal with the owners of main rivers. Somerset County Council as the Lead Local Flood Authority, and the Internal Drainage Boards, will also continue to carry out their usual business regulating ordinary watercourses in Somerset.
The main purpose of SRA involvement with riparian ownership problems is (as ever) to provide an additional resource. So, for example, whereas the county council and IDBs focus on getting single issues sorted out at lots of different sites across Somerset, the new SRA- funded Riparian Responsibilities Officer will seek to deliver greater benefits by targeting areas with multiple problems or opportunities. The Riparian Responsibilities Officer will raise awareness of maintenance responsibilities, encourage riparian owners to undertake maintenance and, where appropriate, undertake enforcement of the Land Drainage Act and Internal Drainage Board byelaws.
Being achieved: A Riparian Responsibilities Officer was jointly appointed by Somerset County Council (SCC) and the IDBs, for the SRA. The officer began work in September 2017, initially for one day a week, quickly moving up to 2.5. SCC and the IDBs worked together to identify and agree an appropriate scope of works to maximise the benefit of this additional resource for the SRA and its partners. Meetings, site visits and research have helped to formalise ways of identifying sites and adding value to forthcoming SRA-funded projects such as the major examination of problems in and around Beckington.
Cannington Flood Alleviation Scheme
Part of the SRA’s Enhanced Programme for 2016-17, carried forward after the scheme’s completion was delayed by the need to divert a gas main. An SRA contribution of £300,000 enabled a £4.35m scheme to go ahead, led by the Environment Agency in partnership with EDF, Cannington Parish Council, Wessex Water and Somerset County Council.
Achieved: A new relief channel to divert flood water away from Cannington and better protect 200 homes and the A39 was completed in mid- July and a Hydro-Brake® flow control structure in late summer 2017. As part of the re-modelling of the area, a new access has been created to The Grange (a large, historic complex of holiday accommodation). CCTV and hydrometry / telemetry equipment have been installed, and fencing and planting carried out. Some final landscaping work was deferred because of bad weather. It is due to be done before the end of June 2018.