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SRA maintenance activities 2016-17

For 2016/17, Somerset Rivers Authority has prioritised schemes and projects which will meet the most pressing needs and deliver the greatest benefits. In particular, Somerset Rivers Authority (SRA) has chosen to prioritise extra maintenance to rivers, roads and structures, such as pumping stations, as existing funding is not enough to cover Somerset’s needs.

Outlined below are all schemes, activities and actions currently in the SRA’s 2016/17 Enhanced Programme for maintenance. Each description is followed by a summary of the planned objectives, outcomes and benefits; in short, why the work is being done.

It’s a vital principle of SRA work that it delivers an extra level of flood protection for Somerset. A final note on each scheme shows whether it represents additional work or additional funding.

Click to download a PDF of the SRA 2016/17 Enhanced Programme for Maintenance.

Maintaining dredged profiles

Carrying out on-going maintenance of those lengths of river that have previously been dredged, such as the original dredging in 2014 of 8km of the River Parrett and River Tone, and the 750m of the Parrett downstream from Northmoor Pumping Station towards the M5. Maintenance dredging will take place of those sections of the river where maintenance is most needed.

Why: Maintenance of dredged profiles to avoid the need for capital dredging in the future.

Extra work

Silt monitoring

On-going survey of River Parrett and River Tone profiles to ensure that maintenance dredging is targeted in the areas most in need.

Why: Identify locations, equations and types of silt build-up to enable maintenance work to be better targeted. By collecting data to better understand the relationship between fluvial and tidal deposition and the associated locations and sources of silt, better management of conveyance can be obtained by optimising dredging activities and better understanding gained of the impact of other possible flood risk solutions (upper catchment).

Extra work

Computer hydraulic modelling

Further hydraulic modelling will be required to test the effectiveness of proposals and the interaction of works at various locations. This will require amending/extending the hydraulic model that the Environment Agency have commissioned. Years 1 and 2 concentrate on the rivers Parrett, Tone and Brue; Year 3 onwards develops other models.

Why: Due to the complex nature of flooding and the way changes in one area can impact on other areas, it is essential that all options are tested in a hydraulic model, prior to being recommended for implementation, to assess their effectiveness (i.e the level of flood risk reduction achieved) and ensure no adverse impacts elsewhere. Modelling all works in a comprehensive model of the system will enable effectiveness, and hence value for money, to be assessed and demonstrate to the wider community that measures being proposed do not have adverse impacts elsewhere, or, that there are adverse impacts.

Extra work

Intermittent asset maintenance

Proposed asset repairs likely to include:

  • Bridge repairs (countywide)
  • North Drain inlet (near Wells)
  • South Hill sluice penstock (north of Burnham–on–Sea)
  • Huntworth Brook (near Bridgwater)
  • Rode Bridge de-silting (River Frome)
  • Spring Gardens channel maintenance (near Frome)
  • Vallis flow gauge repairs (Mells River)
  • Witham Friary flow gauge repairs (Frome)
  • Frome removal and relocation of gauge (St Leonards Weir, Frome)

These are all assets owned by the EA, whose funding bids for maintenance can fall short of what’s required. Unfunded asset repairs are normally placed on an Environment Agency national priority list. Note: the SRA’s proposed asset repairs may change, if the Environment Agency’s list changes.

Why: Asset maintenance and improvement is crucial for the accurate and timely delivery of data and information that shapes and strengthens operational response to flooding and potential flooding. Without SRA funding, the Environment Agency would be reliant on landowners undertaking work or having assets handed to them, or data could be taken from donor sites elsewhere which might be inaccurate for certain locations. This in turn could give rise to problems such as the inappropriate issuing of alerts (causing needless worry to communities).

There is also a value, well-recognised by people across Somerset, in maintaining and improving assets so they perform reliably when required.

Extra funding

Taunton Strategic Flood Alleviation Improvements Scheme

This scheme will work by ‘storing’ water in the upper catchment of the River Tone (above Taunton) in times of flood, releasing this in a controlled and gradual fashion and reducing peak water levels downstream. The aim is to store approximately 1.8 million cubic metres of water. The water storage area would only be used during flood events – most of the time it would be dry and could be maintained for agriculture.

Following outline feasibility, the next steps are detailed feasibility, land acquisition and obtaining all necessary consents to enable the project to be delivered.

Why: The proposed project would store a substantial volume of water in the upper catchment of the River Tone, reducing peak flows downstream during flood conditions. It will allow planned development – housing, employment land and regeneration sites – approximately 4,350 new homes and nearly 10,000 new jobs, in the town centre and at new employment sites – to be safely brought forward. It will mitigate the effects of climate change.

Without such a scheme, existing properties and business premises will face unacceptable levels of flood risk and associated human and economic consequences.

Extra work

Countywide de-silting of structures

Focused on problem areas countywide, a scheme to de-silt waterways beneath engineering structures, i.e. road bridges/culverts. It is proposed that each year a list of priority schemes is identified.

Why: Silting-up is a problem because it can cause damage to an engineering structure (bridge, culvert, etc) or flooding. De-silting increases the flow of water through a structure. It reduces the risk of structural damage caused by pressure, or by floating debris colliding and getting stuck. It also cuts the risk of flooding on roads and in nearby properties. This will also reduce the risk of motorists becoming stuck and requiring resource to rescue them, making inappropriate manoeuvres on the highway, wasted journeys, increased traffic on other roads, highways emergency callouts. SRA funding is required because a lack of Somerset County Council revenue funding means that de-silting is not done as a routine operation.

Extra work

Highway culverts inspections and remedial works in Internal Drainage Board areas

Carry out inspections of circa 700 culverts which cross public highways and, focused on problem areas, repair/remove blockages/increase capacity where appropriate or replace life-expired structures.

Why: To improve conveyance and flood risk management by having a better understanding of structures which have dual functions (flood risk and highway) and where responsibilities are sometimes unclear. Culverts are all vulnerable to potential blockages from debris and vegetation and many were not designed to accommodate the structural loading of modern traffic. There is significant potential for water flow capability to be lost, either by blockage or collapse, and this results in local flooding and traffic disruption. This programme will prioritise the most vulnerable and strategically important culverts for preventative maintenance and so help prevent disruption to residents and road users.

Extra work

River Isle - Isle Brewers bank repairs and badger damage

The village of Isle Brewers near Fivehead benefits from an existing flood alleviation scheme which protects a number of properties. Maintenance is undertaken annually and consists of grass cutting and asset (i.e. flap valves and penstocks) maintenance. Funding via the Government’s Flood Defence Grant-in-Aid is sufficient for this work only. A routine Environment Agency asset inspection highlighted that some banks have badger damage. Funding will repair this damage and exclude the badgers using DEFRA-approved contractors. Other works could include deployment of badger mesh to discourage re- habitation of the banks.

Why: This repair work will ensure that the standard of flood protection afforded to the village of Isle Brewers by the existing defence is maintained.

Extra funding

Countywide Enhanced maintenance - Drain Jetting

This is an enhanced maintenance regime focused on problem areas, in addition to that currently delivered by Somerset County Council to alleviate localised highway flooding.

Why: In conjunction with the programme of gully emptying, the cleaning of highway drains from road gullies to outfall alleviates local highway flooding, with associated safety benefits to highways users.

Extra funding

Countywide Enhanced maintenance - Road Sweeping

This is an enhanced maintenance regime, focused on rural problem areas, in addition to that currently delivered by Somerset County Council to alleviate localised highway flooding.

Why: It is known that the effectiveness of highway drainage systems is severely impeded by debris and detritus accumulating on highway drains, with resulting localised flooding. Road sweeping would offer safety benefits to highway users as well as preventing future clogging of highway drains.

Extra funding

West Somerset Streams - annual maintenance (versus Environment Agency funded biannual)

The Environment Agency currently undertakes routine maintenance work on various main rivers in West Somerset. Reduction in funding has meant that this work can only be delivered on a bi-annual rather than an annual basis. SRA funding will allow an annual maintenance regime to be reinstated on Doniford Stream, Horner Green, Traphole Stream and Washford Stream, plus a one-off pioneer work programme to be undertaken.

Why: As a high proportion of watercourses in West Somerset are classified as 'Rapid Response Catchments', it is important to ensure that channel conveyance is maintained leading to maximum flood water discharge capacity. A number of flood alleviation schemes are in place which provide an enhanced level of protection, but the removal of debris and vegetation from within channels is seen as a priority by the West Somerset Flood Action Group.

Extra funding

Additional de-silting / dredging

Removal of silt from smaller main river channels and viewed rhynes identified at an Internal Drainage Board (IDB) workforce workshop in 2014. Over 250km across IDB areas identified.

Why: Increased conveyance.

Extra work

Funding for programme of Enhanced Maintenance of Sedgemoor District Council flood relief and drainage assets

Enhanced maintenance of land drainage schemes and structures within Sedgemoor. 

Why: Sedgemoor District Council currently maintains a number of land drainage schemes, structures and channels within its area. These schemes provide drainage at various locations: Wedmore, Blackford, North Petherton, Cheddar, North Newton, Greinton and Goathurst. In addition, land drainage structures are identified from time to time which may require maintenance. If it is assessed as appropriate, Sedgemoor District Council may undertake maintenance activities using its permissive powers to ensure that structures remain effective. Therefore, this funding is requested so that we can continue - and increase our ability - to maintain these schemes, to undertake surveys and assessments, and to enhance our capacity to undertake preventative maintenance for the benefit of the communities these assets serve. 

Clearly, working in partnership with other organisations in the maintenance of existing land drainage structures and channels should be a priority principle of the SRA, alongside the installation of new assets. Existing schemes make up a fundamental part of land drainage within Somerset.

Extra work 

Flood alert systems

Flood warning and flood telemetry systems have been improving in recent years and several providers now offer sophisticated flood detection devices that provide real-time information. This project proposes to try out flood alert systems in Somerset.

Why: If water height is monitored in real time, and pre-determined danger levels are reached, information can be sent back to a service provider, warnings can be automatically triggered via text and email and flashing signs and diversions can be activated. Technology also allows for warnings to be broadcast via text message and email to numerous third parties. Emergency services could be alerted, or local radio stations.

Multi-level warnings can be generated according to the height of the water. Levels can be configured to suit the particular nature of a site or a local authority’s requirements. For example: open, closed to cars, closed.

Such a system could significantly reduce the risk of vehicle damage or personal injury, particularly when it is dark.

Extra work

Sustainable Urban Drainage Systems (SuDS) Inspections

Major developments are required to use SuDS for surface water drainage, but no authority is funded to inspect the construction of SuDS to ensure they comply with approved plans. SRA funding will be used to inspect new SuDS schemes to ensure compliance and review existing SuDS schemes including:

  • Blackbrook Barton
  • Chelston Business Park
  • Farriers Green, Monkton Heathfield
  • Cotford St Luke (all Taunton Deane)
  • East Huntspill (Sedgemoor)
  • Houndwood, Street
  • North of Wells Road, Glastonbury (Mendip)
  • New Barns, Wincanton
  • Canal Way, Ilminster
  • Land adjacent to hospital, South Petherton (all South Somerset)

Why: The objectives of this proposal are two-fold. First to ensure that new SuDS that are not adopted by a Water & Sewage Company, Highway Authority or other public body are constructed and therefore function as designed and approved. The second objective relates to existing schemes and is the assurance that these SuDS schemes are functioning as designed and approved.

A report will examine the effectiveness of schemes, and what actions (if any) need to be undertaken. It will study whether schemes have been adequately designed, whether they were constructed as designed, whether there are any deficiencies, and whether they are being adequately maintained. It will confirm whether the public perception that SUDS schemes are not working, and are a major cause of downstream flooding, is correct, or provide evidence to the contrary.

Extra work

West Sedgemoor and Aller Moor Viewed Rhynes Enhanced Maintenance

Carrying out maintenance of all viewed Rhynes in West Sedgemoor and Aller Moor on an annual basis rather than a biennial basis.

Why: Increased conveyance.

Extra funding

CCTV Surveys of privately owned drains

Surveys on culverts on private property where it’s suspected there are issues with the flow of water and/or a lack of information about important watercourse networks. Accurate knowledge will enable requests to riparian owners to remedy problems - and/or enforcement.

Why: Greater understanding of where there are blockages will enable these problems to be put right, by requesting riparian owners to remedy the problems or carry out enforcement. Lead Local Flood Authority officers often get involve in neighbourhood disputes. It is often very difficult to ascertain ownership of culverted watercourses without carrying out a CCTV survey. Furthermore, enforcement cannot be taken against anyone unless proof is obtained about the location of culverts.

Extra work

Encouraging reduction of urban and village runoff

'Slow the Flow' and natural flood management projects are seeking to reduce flooding by holding back the flow from rural areas but runoff from urban areas, especially those areas constructed before the advent of SuDs, also contributes to flooding. This activity seeks to address this by a campaign to raise awareness of steps that individuals can take and encourage them to do so.

Why: The objective is to raise awareness of the steps that individuals can take to reduce runoff and hence flooding. A publicity campaign showing the benefits of water butts, rainwater harvesting, replacing concrete drives with permeable paving, etc, will be undertaken to encourage uptake by showing the benefits.

Extra work

Sponge EU Project

A demonstration project to retrofit Sustainable Urban Drainage Systems (SuDS) to a large retail park/industrial estate in Taunton or Bridgwater to show what can be achieved in an urban area. If the application is successful, the project will be 60% funded by the EU 2 Seas Programme.

Why: The objective is to raise awareness of the steps that owners of large impermeable areas can take to reduce runoff and hence flooding. A SuDS retrofit will be undertaken to demonstrate the environmental and flood risk benefits that can be achieved. Runoff from urban areas, especially those areas constructed before the advent of SuDS, contributes to flooding. This activity seeks to address this.

Extra work

Rain garden project

A small rain garden demonstration project to show the environmental and runoff reduction benefits that can be achieved. The project will be 50% funded by Wessex Water.

Why: The objective is to raise awareness of what can be achieved through the installation of a rain garden. The results of the installation will be used to encourage others.

Extra work

South Somerset enhanced and programmed maintenance

South Somerset District Council (SSDC) will review nearly 40 sites where programmed maintenance of flood alleviation schemes is currently carried out and determine whether the work can be made even more effective by doing more to the existing sites or indeed extending the scope.

This work could be one-off maintenance operations but could also include reviewing 55 debris capture screens. The design and construction of these screens will be looked at to identify if these could be improved and as such be able to more readily maintain flows.

Watercourses in selective areas will be looked at where, for whatever reason, any effective maintenance is currently not carried out and actioned as necessary.

Why: The aims of this proposal are to investigate sites where SSDC carries out planned maintenance works and verify effectiveness. It would also include a Health & Safety (H&S) review and replace screens, etc, as necessary to improve H&S.

It would provide information on existing planned maintenance and verify the effectiveness. It would also seek to improve efficiencies by improving the designs and replace as appropriate. This will have a knock-on effect on improved H&S of sites.

The outcome will be delivered by producing records of which sites have been reviewed and where further action is needed and how that action is to be pursued.

Extra work

Tree work

Removal of trees and woody vegetation from channels identified at an Internal Drainage Board (IDB) workforce workshop in 2014. Over 60km across IDB areas identified. Needs to be assessed on evidence on a case-by-case basis.

Why: Increased conveyance. Work has not been carried out before, as necessary, because of higher priority projects and limits on existing funding. If the work is not done now then the channels’ capacity will go on getting smaller, thereby increasing flood risk to local areas.

Extra work

Planning Requirements

What developers can be asked to provide is laid down in planning legislation and the extent to which planning requirements can be created is not widely understood. The project will set out how planning requirements to reduce runoff can be determined and the extent they can be created.

Why: Runoff from new development is controlled through the planning process and what developers can legitimately be required to provide is set out in planning legislation and guidance. This needs to be better understood so that it's known to what extent planning requirements can be created, eg by requiring rainwater harvesting on all new development. If requirements are not possible, this needs to be clearly explained to the public. If it is considered that changes to legislation are required, the route for doing so needs to be set out.

Extra work

Riparian enabling and enforcement

Increased resource to ensure that riparian owner responsibilities for ditch maintenance are carried out.

Why: The aim of this proposal is to work with communities to ensure that watercourses are maintained throughout the county and flood risk is reduced. A riparian enabling and enforcement officer will take a proactive approach to engaging communities and farmers and provide advice to ensure that the flow of water is maintained in ordinary watercourses and that flood risk is reduced. The alternative is a volunteer scheme but it is difficult for a volunteer to carry out enforcement.

Extra funding

Countywide Enhanced maintenance - Gully emptying

Focused on problem areas, an enhanced maintenance regime in addition to that currently delivered by Somerset County Council to alleviate localised highway flooding. This programme calls on a wide variety of data, such as Environment Agency surface water flooding maps, historical records of highway service requests, highway maintenance history and so on. It's propose to cleanse gullies every six months at locations across the county which are most susceptible to flooding.

Why: This programme of gully emptying is designed to mitigate high risk areas (top 20%; ie between 4,000 and 7,000 gullies) and to alleviate localised highway flooding, with associated safety benefits to highway users. It willl keep roads open, communities accessible and safeguard properties from flooding.

Extra funding

Natural Flood Management: Slow the Flow

There is growing demand through the West Somerset Flood Group for Natural Flood Management advice and support. There is currently no funding for Land Management advice in West Somerset or Frome catchments because they don't connect to the Levels.

Why: Alleviate local flooding in quick-response catchments of West Somerset, working with and through the West Somerset Flood Group. Alleviate local flooding in Frome catchments. Use the SRA's Heart of South West Local Enterprise Partnership Growth Deal money to give capital grants for natural flood management schemes where small-scale soft engineering is necessary.

Extra work

Building Local Resilience (9 objectives/work programmes)

Continued employment of one community resilience development worker to provide inspiration, support, advice, information and practical help to communities, households, businesses, and landowners across Somerset to encourage and enable them to become more resilient.

Project to use community development principles of engagement, participation, inclusion, self-determination and partnership.

Why: Objectives -

1) To encourage and enable every town and parish in Somerset at risk of flooding to engage with local resilience planning and, beyond production of plans, to encorage and enable communities to move forward with preparedness / adaption at household, business & community level.

2) To develop a model of "a resilient community" to set minmum standards, promote best practice & improve understanding of risks & expectations.

3) To build on the work of Community Resilience In Somerset Project (CRISP) to develop and share tools, techniques and materials to support community resilience activities and to create an ongoing programme of events and training to embed community resilience.

4) To establish an annual or bi-annual Community Resilience Forum to maintain and support a developing network of dedicated voluntary community leaders.

Extra work

If you would like to get in touch please contact us at sra@somerset.gov.uk or tel: 01823 355111
The Flood Action Plan is now overseen by the Somerset Rivers Authority and can be contacted on the above.