Bridgwater Tidal Barrier Scheme

Long List of Options - Consultation Response

FINAL Contents

1.0 INTRODUCTION ...... 3 1.1 Background to the project ...... 3 1.2 Long list of options consultation ...... 3 2.0 CONSULTATION RESPONSES ...... 5 2.1 Analysis of responses ...... 5 2.2 Summary of the main comments and concerns ...... 5 2.3 Further work undertaken ...... 6 3.0 RESPONSE TO COMMENTS AND CONCERNS ...... 7 3.1 Responses to the main comments and concerns raised by consultees ...... 7 3.2 Options assessment ...... 9 3.3 Short list option selection ...... 15 4.0 WHAT HAPPENS NEXT? ...... 15 1.0 INTRODUCTION 1.1 Background to the project Sedgemoor District Council (SDC) and the Environment Agency (EA) are promoting a Tidal Barrier Scheme to protect Bridgwater and areas of the Somerset Levels and Moors from tidal flooding. Sustainable development of Bridgwater and the surrounding area relies on flood risk infrastructure and the Tidal Barrier Scheme is a key component of the 20 Year Flood Plan for Somerset that aims to reduce the frequency, duration and severity of flooding.

The EA and SDC are working together on the project, with support from the Somerset Rivers Authority as a key contributor using funding from the Heart of the South West Local Enterprise Partnership.

The tidal barrier would be constructed across the River Parrett north of Bridgwater. The barrier would consist of abutments on either side of the river, one or two gates and a control building. The barrier would normally be open, but would be closed when a very high tide was expected to prevent the tide travelling upstream and overtopping defences and flooding property and infrastructure. While the barrier was closed river flows would be stored in the river channel upstream. At times of high fluvial flows, the barrier could be closed to keep out the tide and hence create more storage space for river flows. Downstream of the barrier, existing flood defences either side of the River Parrett would be maintained or improved to ensure that the barrier is not bypassed by flows in the floodplain and that flood risk is not increased to property and infrastructure elsewhere. 1.2 Long list of options consultation The EA are undertaking an assessment of options for the barrier location and type and the flood defences downstream of the barrier. As the first stage of the assessment process, 7 potential barrier locations have been identified and the advantages and disadvantages of each location have been considered in order to narrow down this long list of options to a smaller number for more detailed assessment. The 7 barrier locations are shown on Figure 1.

The assessment has taken into account factors such as the area protected, capital and maintenance costs, silt management, ground conditions, environmental impact, navigation, flood defences and operation of the barrier.

Consultation with the public and stakeholders is key part of the assessment process and as the project moves forward regular consultation events will be held. SDC and the EA held the first stakeholder workshop and a public exhibition at Bridgwater Arts Centre on 10 March 2016. Invitations were sent to 32 stakeholder organisations who might have an interest in the project and the public exhibition was advertised via social media and on SDC’s website and Somerset Rivers Authority website. The event was also promoted through community groups. The material used at the consultation events was also uploaded to the SDC website following the event, web link below.

http://www.sedgemoor.gov.uk/bridgwaterbarrier

The aim of the consultation events was to inform attendees about the project and the options being considered, discuss their views and receive feedback on the long list of 3 options in order to feed in to the option selection process. The background to the project and the assessment of the potential sites was presented along with the initial recommendation for which sites might be taken forward.

Figure 1 – Long List Barrier Location Sites © Crown copyright and database rights 2016 OS 100026380

4 2.0 CONSULTATION RESPONSES 2.1 Analysis of responses The workshop was attended by 14 stakeholder organisations and 125 people attended the public exhibition. SDC and EA staff were available at the events to discuss the project and answer questions raised.

Feedback was provided to the project team via forms completed on the day or submitted later and via e-mails sent to the project e-mail address: [email protected].

A total of 37 responses and other communications were received, which comprised:

Form of response: Feedback forms (paper or email) 24 E-mails 11 Letters 2

The consultation sought an indication of support for the 7 barrier locations as well as comments on other issues that might impact the scheme. The responses were analysed and where support for a particular site(s) was indicated, the preferences were as follows:

Barrier 1 2 3 4 5 6 7 Location No. Supporting 3 1 3 9 7 6 9

Stakeholders who provided feedback to the consultation included:

Durleigh Parish Council, Bridgwater Town Council, Sedgemoor District Councillors, Friends of Bridgwater Docks and Canal, Wessex Water, Somerset Drainage Boards Consortium, Military Boats, Royal Yachting Association, Inland Waterways Association, Otterhampton Parish Council, Somerset Wildlife Trust, RSPB, Historic England and local residents of Bridgwater and the surrounding area.

The feedback received is included in Long List Consultation Feedback. Personal details have been redacted.

2.2 Summary of the main comments and concerns The overall feedback from attendees was that the construction of a barrier to reduce tidal flood risk to Bridgwater would be positive for the town and the surrounding area.

The main comments and concerns were:

 Barrier locations further downstream would provide flood protection to a widest area;

 Sea level rise is anticipated to be around 1 m over the next 100 years, downstream defences will not be viable in the future;

5  How the location choice could impact on future development of the town;

 A barrier close to the town will be visually intrusive;

 Who will be responsible for maintaining flood banks and bearing the associated costs in the future?

 The barrier should include a road bridge;

 The barrier will impact on navigation, it should include a lock and the possibility of access for pleasure boats and small craft;

 Impact of the barrier on Kings Sedgemoor Drain;

 Considerations on water management should be analysed in more detail, the barrier should be able to pen water upstream;

 The barrier should be a tidal exclusion sluice to reduce silt movement upstream;

 Sewers crossing the river and proximity to Chilton Trinity sewage treatment works outfall;

 Questions on associated project costs and benefits;

 The plans should not adversely impact on nature and the environment and in particular Natura 2000 sites.

 How often will the barrier be operated? The key messages from the consultation were that the scheme has general support, there was more support for Locations 4 – 7 than for 1 – 3 but that there were concerns about all locations that would need to be addressed in future stages of the appraisal.

2.3 Further work undertaken As a result of the comments received, Location 2 will still be considered so that the following issues can be further examined:

 The impact of the barrier on the discharge from Kings Sedgemoor Drain - we will undertake hydraulic modelling to understand the interaction between barrier and the KSD.

 How the barrier and associated flood defences will protect potential development sites – we have discussed the future development of Bridgwater with SDC to understand the position with the Local Plan and to consider how the barrier scheme will support the Plan.

 Re-examine the advantages of Location 2 including the potential for a future road crossing – we have considered some aspects of the assessment for Location 2 in

6 more detail and discussed the potential for future development and a road crossing with SDC.

3.0 RESPONSE TO COMMENTS AND CONCERNS

3.1 Responses to the main comments and concerns raised by consultees • Barrier locations further downstream would provide flood protection to a widest area. The project will consider the best way of providing flood protection to Bridgwater and this will be a combination of a barrier and improved flood defences downstream. We will work out the location for the barrier to maximise flood protection and that provides the best value for money over its lifetime.

• Sea level rise is anticipated to be around 1m over the next 100 years, downstream defences will not be viable in the future, therefore the barrier should be located downstream of Dunball. The scheme assessment will be over a 100 year period which will include the impact of sea level rise and future works required to mitigate this impact. The overall strategy for future flood defence is detailed in the 2010 Parrett Estuary Flood Risk Management Strategy. It is likely that flood defences will have to be raised in the future to maintain standards of flood protection. In some areas this would be difficult, eg between Drove Bridge and Silveys Wharf and through Dunball, and it may require re-aligning defences in some areas. However our assessment is that the cost of these defences is significantly less than the additional cost of a barrier downstream of Dunball.

• The location choice could impact on future development of the town. The protection of both existing property and future development sites is a key objective of the project. The barrier scheme will help to provide the confidence that further development is sustainable.

• A barrier close to the town will be visually intrusive. We are carefully considering the impact of the barrier and associated works on the townscape and residents of Bridgwater and the surrounding area. Visual impact, noise and traffic will be key issues to be addressed in the environmental assessment of the sites.

• Who will be responsible for maintaining flood banks and bearing the associated costs in the future? Maintaining the flood banks will continue to be part of the EA’s role. The responsibilities for the maintenance and operation of the barrier are under discussion between SDC and EA.

• The barrier should include a road bridge. There are currently no firm proposals for a road crossing north of Bridgwater and this is not something SDC and the EA will be promoting as part of this project. However if firm proposals come forward from other parties within the timescales of this project we will consider them.

• The barrier will have an impact on navigation, it should include a lock and the possibility of access for pleasure boats and small craft.

7 It is the intention that the impact on navigation will be as low as possible. Navigation and any need for a lock will be included in the short list assessment and will depend on the location, form of barrier and frequency of operation.

• What will the impact of the barrier be on Kings Sedgemoor Drain (KSD)? Initial hydraulic modelling has indicated that if a barrier were to be situated downstream of the KSD outfall there could be a small beneficial impact in terms of the volume of water that could be discharged through the outfall in a tidal cycle.

• Considerations on water management should be analysed in more detail, the barrier should be able to pen water upstream. Penning water would add significant complexity and cost to the project due to the increased frequency of barrier operation and the type of gate that may be required for the dual purpose of penning water and excluding surge tides. Penning water may also have an impact on the existing drainage systems in Bridgwater which discharge to the river under gravity via low level outfalls. However we will consider in the assessment of the gate types and operation how the barrier could be operated to maintain an upstream water level.

• The barrier should be a tidal exclusion sluice to reduce silt movement upstream. A tidal exclusion sluice has been previously discounted because of the impact on the saltwater environment upstream, the impact on water quality due to the reduced flushing effect of the tide and the increased sediment deposition downstream. However we will consider how the barrier could be operated to provide silt management and fluvial flood management benefits.

• Sewers crossing the river and proximity to sewage treatment works outfall. We are aware of the sewer crossings and will carefully consider the impact of a barrier on the treatment works discharge and on the Burnham bathing water improvements project.

• What are the project costs and benefits? The current project cost estimate is £30 – 75m depending on the option selected. The potential long term economic benefits due to the reduction in flood risk are in excess of £1,000m.

• The plans should not adversely impact on nature and the environment. A key part of the assessment is the consideration of environmental impacts and opportunities. We will be seeking options which minimise the impacts and where impacts are unavoidable implementing suitable mitigation measures. We will also look for opportunities to enhance the environment through the project. We will assess potential impacts on the Natura 2000 sites on the Somerset Levels and Moors and the managed realignment site at Steart.

• How often will the barrier be operated? Initial analysis indicates that the barrier could be operated around 30 times per year for all purposes including tidal and fluvial flood risk management and maintenance. In the future the barrier may be operated more frequently due to sea level rise.

8  How will the barrier and associated flood defences protect potential development sites? The Bristol Road North development site and the EDF park and ride site to the north of Dunball will be protected by the barrier and improved downstream flood defences. We will also consider how the scheme could protect a potential development site to the north of Chilton Trinity into the future. Whichever barrier location is chosen, the scheme will provide the same level of protection.

 Re-examine the advantages of Location 2 including the potential for a future road crossing. We have not discounted Location 2 and are preparing a separate note on the advantages and disadvantages of a barrier at this site.

3.2 Options assessment We have considered the feedback received from the consultation and have reviewed and updated our assessment. The full assessment matrix is included below along with a summary of the criteria used.

The key points that differentiate between barrier locations are summarised below.

Advantages Disadvantages

 Beneficial for discharge from KSD  Very large barrier with very high capital under some circumstances. and maintenance costs.  Defence infrastructure moved  Significant downstream bank raising to downstream of Bridgwater. mitigate for impact of barrier on water Location 1  No spatial constraints for construction levels. or permanent works.  Within Severn Estuary environmentally designated sites.  Remote site, access for construction and operation difficult.  Beneficial for discharge from KSD  Very large barrier with high capital and under some circumstances. maintenance costs.  Potential for combining with road  Significant downstream bank raising to crossing and facilitating future mitigate for impact of barrier on water development site. levels. Location 2  Defence infrastructure is moved  Only 700m from Severn Estuary downstream of Bridgwater. environmentally designated sites.  No spatial constraints for construction  Potential for significant geomorphological or permanent works. impact on the Parrett.  Impact on navigation of commercial vessels to Dunball.  No spatial constraints for construction  Large barrier with high capital and or permanent works. maintenance costs.  Potential for significant geomorphological Location 3 impact on the Parrett.  Not suitable for combining with road crossing.  Potential for combining with road  Large barrier with high capital and Location 4 crossing and facilitating future maintenance costs. development site.

9  No spatial constraints for construction  Potential for significant geomorphological or permanent works. impact on the Parrett.

 Smaller barrier with capital costs  Immediately downstream of Chilton Trinity some £10-30 million less than STW outfall, may have water quality locations downstream and lower implications. Location 5 maintenance costs.  Narrower channel and hence higher flow  Good access for construction and velocities will make construction more operation. difficult.  Smaller barrier with capital costs  Narrower channel and hence higher flow some £15-35 million less than velocities will make construction more locations downstream and lower difficult. maintenance costs.  West bank adjacent to historic landfill & Location 6  Good access for construction and competent foundation strata at >20m operation. depth.  Minimal geomorphological impact.  Upstream of STW outfall.  Smallest barrier with capital costs  Narrower channel and hence higher flow some £15-35 million less than velocities will make construction more locations downstream and lower difficult. maintenance costs.  Service diversions may be required.  Good access for construction and  May be significant difficulties and high cost Location 7 operation. in improving downstream defences,  Minimal impact on navigation. particularly on the right bank, due to  Minimal geomorphological impact. spatial constraints.  Upstream of STW outfall.  Spatial constraints for construction of barrier.  West bank near to historic landfill.

In the assessment matrix a red, amber, green colour system is used to indicate for each assessment criteria either,

 Minor, Moderate or Major impact or;  The relative impact within a particular criteria.

Summary of assessment criteria:

Navigation: Impact on commercial and recreational navigation on the River Parrett and on the operations of the Port of Bridgwater. The effects are assessed through consideration of the direct impacts during construction and in the permanent condition.

Future connection to inland waterways: In the future there are aspirations to improve the connection to the inland waterways and increase recreational use further upstream. This includes the concept of using the tidal barrier structure to impound (pen) water behind it and create a safer waterway over a longer period of time. If the barrier is operated frequently (ie for tidal exclusion) a lock may be required to allow navigation upstream. Some of the locations would offer a reduced capacity to accommodate such a structure.

Future use as a tidal exclusion sluice: The location should not preclude its potential use at a future date as a tidal exclusion sluice, this function is largely dictated by the regular operation of the closure mechanism of the gate.

10 Geomorphology: The introduction of an impermeable structure within the channel would cause changes to the flow hydrodynamics and the geomorphological response of the river is a significant concern from an environmental, navigational and flood risk management perspective.

Fisheries: The direct land take necessary for the construction of the structures will reduce potential habitats for non-migratory species, and the operation of the barrier will affect the local hydrodynamics through the obstruction of flow, causing changes to local habitats as well as the salinity of upstream areas.

Water quality: Even if the long-term influence of the project is not expected to have a significant effect on the water quality of adjacent and downstream areas, some impacts are likely to occur during the construction phase of the project.

Impact on biodiversity/statutory features: There are a number of different environmental designations which may potentially affect the location of the tidal surge barrier, including a Special Area of Conservation (SAC), Special Protection Area (SPA), and a Site of Special Scientific Interest (SSSI).

Visual / landscape: Impact on the visual amenity and landscape character of nearby settlements and areas used by the public. The barrier structure, particularly if a raised gate type is required, could have a significant visual impact, which is highly dependent on the location of the barrier.

Recreation: Impact the barrier may have on recreation by considering the existing land use of the area.

Heritage: There are a number of statutory and non-statutory heritage designations distributed along the River Parrett and within nearby settlements, and the direct impact of barrier construction on heritage assets is considered.

Strategic infrastructure: The barrier provides benefit to infrastructures because of the increased standard of flood protection but there are impacts due to temporary or permanent closure or diversion of a section of the river or road network or utility/service that may interrupt the infrastructure operation.

Downstream defence raising: The extent and level of tidal flood defence bank raising downstream of each barrier location to prevent outflanking of the barrier and protect existing property and development sites.

Upstream storage: The capacity of the river channel upstream of the barrier locations to store river flows when the barrier is closed.

Land drainage (outfalls): Impact on the discharge from land and surface water drainage outfalls and the KSD when the barrier is closed.

11 Level of maintenance: The maintenance requirements are highly dependent on the specific location, a larger structure spanning a wider section of river will necessitate additional maintenance activities from a mechanical and electrical engineering perspective.

Operational requirements: The operational requirements of the barrier are diverse, covering the need to both provide the flood protection and not negatively impact upon navigation. The barrier must also be able to operate under adverse hydraulic conditions.

Access: Permanent access to the both sides of the barrier and the control building under all conditions.

Geotechnical and geo-environmental issues: The main concern from a geotechnical perspective is the depth to competent foundation strata/bedrock. Consideration is also given to the proximity to historic landfill sites.

Additional planning/regeneration benefits: Benefit to future potential development sites and infrastructure.

Construction/buildability: The assessment is based on physical and environmental constraints applicable to each site and the technical requirements and mitigation required to deliver the permanent works.

Capital cost: The order of capital cost for each barrier location and the associated downstream defences.

Whole life cost: Operational and maintenance costs for the barrier and downstream defences. The average O&M whole life cash cost for the barrier has been estimated based on a range of 1% to 2% of the capital cost per annum over the 100 year design life of the barrier. For larger sized barriers this can increase to between 3% and 5%. The downstream embankments cost has been assumed that will remain as per the existing.

12 BRIDGWATER TIDAL BARRIER SCHEME Major impact/relatively ‐ unfavourable Date : 06/06/2016 LONG LIST OPTION ASSESSMENT MATRIX Moderate impact/relatively ‐ neutral Version: 4 Minor impact/relatively ‐ favourable

Option Option 1 Option 2 Option 3 Option 4 Option 5 Option 6 Option 7

Assessment Criteria Opposite Pawlett Hill Downstream of Dunball Wharf Upstream of KSD Outfall Downstream of Express Park Express Park downstream of Chilton Trinity STW Express Park upstream of Chilton Trinity STW Downstream of A39 Bridge Significant temporary impact on navigation using Dunball Significant temporary impact on navigation using Dunball Minor adverse temporary impact on navigation using Silvey's Minor adverse temporary impact on navigation using Silvey's Minor adverse temporary impact on navigation using Silvey's Minor adverse temporary impact on navigation using Silvey's Upstream of Silvey's Wharf so temporary closure of channel to Wharf but mitigated by temporary bypass channel and Wharf but mitigated by temporary bypass channel and Wharf ‐ no usage at present which allows temporary closure of Wharf ‐ no usage at present which allows temporary closure of Wharf ‐ no usage at present which allows temporary closure of Wharf (no usage at present) which allows temporary closure of navigation during construction has no impact (recreational associated navigation safety measures during construction. associated navigation safety measures during construction. channel to navigation during construction. However very poor channel to navigation during construction. Reasonable line of channel to navigation during construction. However poor line channel to navigation during construction. However poor line navigation upstream very limited at present). Reasonable line Reasonable line of sight through barrier to see approaching Poor line of sight through barrier to see approaching vessels line of sight through barrier to see approaching vessels from sight through barrier to see approaching vessels from opposite of sight through barrier to see approaching vessels from of sight through barrier to see approaching vessels from of sight through barrier to see approaching vessels from Navigation impact vessels from opposite sides of barrier. Potential for permanent from opposite sides of barrier due to sharp bend in channel opposite sides of barrier due to sharp bend in channel nearby sides of barrier. opposite sides of barrier due to bend in channel nearby on opposite sides of barrier due to sharp bend in channel nearby opposite sides of barrier although slight bend in channel nearby impact on navigation to Dunball due to closure on high tides. nearby on downstream end. Potential for permanent impact on on downstream end. upstream end. on downstream end. on upstream end. navigation to Dunball due to closure on high tides.

Although temporary impact during construction, no permanent Although temporary impact during construction, no permanent Although temporary impact during construction, no permanent Although temporary impact during construction, no permanent Although temporary impact during construction, no permanent Although temporary impact during construction, no permanent Although temporary impact during construction, no permanent Future connection to inland adverse impact on existing ability for vessels to navigate adverse impact on existing ability for vessels to navigate adverse impact on existing ability for vessels to navigate adverse impact on existing ability for vessels to navigate adverse impact on existing ability for vessels to navigate adverse impact on existing ability for vessels to navigate adverse impact on existing ability for vessels to navigate between Bridgwater Bay and the inland waterways i.e. between Bridgwater Bay and the inland waterways i.e. between Bridgwater Bay and the inland waterways i.e. between Bridgwater Bay and the inland waterways i.e. between Bridgwater Bay and the inland waterways i.e. between Bridgwater Bay and the inland waterways i.e. between Bridgwater Bay and the inland waterways i.e. waterways Bridgwater and Taunton Canal. Bridgwater and Taunton Canal. Bridgwater and Taunton Canal. Bridgwater and Taunton Canal. Bridgwater and Taunton Canal. Bridgwater and Taunton Canal. Bridgwater and Taunton Canal.

The requirement for access to Dunball Wharf and Silvey's The requirement for access to Dunball Wharf and Silvey's Interface with limited navigation use of Silvey's Wharf Interface with limited navigation use of Silvey's Wharf Interface with limited navigation use of Silvey's Wharf Interface with limited navigation use of Silvey's Wharf No interface with commercial navigation as upstream of both Wharf severely limits (possibly prevents) the potential future Wharf severely limits (possibly prevents) the potential future particularly during spring tides potentially limits future use of particularly during spring tides potentially limits future use of particularly during spring tides potentially limits future use of particularly during spring tides potentially limits future use of Dunball Wharf and Silvey's Wharf and adjacent to A39 Drove use of the barrier as a tidal exclusion sluice. This is because the use of the barrier as a tidal exclusion sluice. This is because the barrier as a tidal exclusion sluice. barrier as a tidal exclusion sluice. barrier as a tidal exclusion sluice. barrier as a tidal exclusion sluice. Bridge which is the current practical limit of commercial regular lowering and raising circa 107m wide gate (or regular lowering and raising circa 82m wide gate (or equivalent Regular lowering and raising circa 74m wide gate (or Regular lowering and raising circa 74m wide gate (or Regular lowering and raising circa 46m wide gate each tide for Regular lowering and raising circa 38m wide gate each tide for navigation. It is considered unlikely that commercial navigation equivalent series of gates) each tide for tidal exclusion would series of gates) each tide for tidal exclusion would be extremely equivalent series of gates) each tide for tidal exclusion would equivalent series of gates) each tide for tidal exclusion would tidal exclusion would be onerous and have consequences on tidal exclusion would be onerous and have consequences on will be extended upstream, therefore there is no likely limit on Future use as tidal exclusion be extremely onerous and have significant consequences on theonerous and have significant consequences on the design life of be onerous and have significant consequences on the design be onerous and have significant consequences on the design the design life of the gate(s) and associated MEICA as well as the design life of the gate(s) and associated MEICA as well as the possible future use as a tidal exclusion sluice. design life of the gate(s) and associated MEICA as well as whole the gate(s) and associated MEICA as well as whole life O&M life of the gate(s) and associated MEICA as well as whole life life of the gate(s) and associated MEICA as well as whole life whole life O&M costs but less than wider more complex gate whole life O&M costs but less than wider more complex gate Operating circa 27m wide gate on a regular basis for tidal sluice life O&M costs. costs. O&M costs. O&M costs. systems downstream . systems downstream . exclusion, although implications on gate design life and O&M costs, relatively not as great when compared to wider more complex gate systems required downstream.

Located on Cannington Bends within an area of the estuary Located approx. 700m downstream of Dunball Wharf and close Located on a tight meander within the estuary upstream of Located 400m upstream from Option 3. The channel width (at Located just downstream of a tight meandering section of the Located between two tightly meandering areas of the estuary. Located downstream of the A39 road bridge along a relatively known as Pawlett Gore Sands, so named due to the presence of to a sharp (almost right angled) bend in the channel planform. Dunball Wharf. Bankfull channel width is approximately 230m bankfull) dramatically narrows here to approx 90m and is estuary. Bankfull width is approx 55m with a central low flow Bankfull width is approx 52m with a central low flow channel. straight section of the estuary. Bankfull width is approx 45m a large sand bar. The channel is approx 170m wide in this The low water channel is known to move from one side of the and there is a large sediment bar in the centre of the channel confined by flood embankments along both banks. There is a channel. The flood embankments are located close to the edge The flood embankments are slightly set back from the channel with a central low flow channel. The flood embankments are location at bankfull, and there is a low flow channel which lies channel to the other just upstream of this location. The channel (likely mud, silt and sand) which indicates that the present low water channel which may migrate within the wider of the channel along the left bank in particular, which is edge and are vegetated by reeds. slightly set back from the channel edge and the banks are along the left bank but may migrate within the wider channel. is approx. 120m wide and the embankments are located close estuary planform may be out of regime and prone to sediment estuarine channel. vulnerable to erosion and coastal squeeze. vegetated by reeds. The embankments are located close to the edge of the estuary to the estuary edge particularly along the left bank and are deposition. The flood embankments particularly those along Less impact on geomorphology due to stability of the low water and therefore may confine the planform of the estuary in this vulnerable to erosion and slumping. the left bank are very close to the estuary edge and are Potential impact due to uncertainty regarding Potential impact due to uncertainty regarding channel. Less impact on geomorphology due to the stability of the low location. vulnerable to erosion and slumping. The low water channel can geomorphological change in the longer term and potential geomorphological change in the longer term. water channel and presence of road bridge confining the Potential impact due to uncertainty regarding become multi‐channel around the large sediment bar. movement of the low water channel. existing planform of the estuary in this location. Potential impact due to uncertainty regarding geomorphological change in the longer term and potential geomorphological change in the longer term and potential movement of the low water channel. Potentially significant impact due to uncertainty regarding Width of barrier requires construction of base in at least two Geomorphological impact movement of the low water channel. geomorphological change in the longer term and potential halves. Temporary significant impact from creating circa 100m Large width of barrier requires construction of base in at least movement of the low water channel. long bypass channel for navigation through sand bar/accreted Large width of barrier requires construction of base in at least two halves. Temporary significant impact from creating circa area on right side of channel. two halves. Temporary significant impact from creating circa 300m long bypass channel for navigation through sand This is exacerbated by the barrier width being similar to that for 300m long bypass channel for navigation through sand bar/accreted area on right side of channel. Option 4 further upstream with a circa 150m long closure bar/accreted area on right side of channel. abutment tying into the right hand bank just upstream of the KSD outfall with a risk of increased sediment deposition in front of the KSD gravity sluices and the Dunball Wharf quayside.

Salmon and eel are the only known migratory species. The Baseline conditions are as Option 1 although proportion of Baseline conditions are as Option 1 although proportion of Baseline conditions are as Option 1 although proportion of Baseline conditions are as Option 1 although proportion of Baseline conditions are as Option 1 although proportion of Baseline conditions are as Option 1 although proportion of Parrett is an Index river for eels and is therefore included in the freshwater species are likely to increase and saltwater freshwater species are likely to increase and saltwater freshwater species are likely to increase and saltwater freshwater species are likely to increase and saltwater freshwater species are likely to increase and saltwater freshwater species are likely to increase and saltwater South West River Basin District (SWRBD) Eel Management Plan decrease further upstream. Direct landtake of in‐channel decrease further upstream. Larger direct landtake of in‐channel decrease further upstream. Direct landtake of in‐channel decrease further upstream. The narrower barrier width decrease further upstream. The narrower barrier width decrease further upstream. The narrower barrier width under the EC Eel Recovery Plan (Council Regulation No habitat progressively less as location moves upstream. habitat as wider channel width at this location; two channels habitat progressively less as location moves upstream. proposed at this site is significantly less than some other proposed at this site is significantly less than some other proposed at this site is significantly less than some other 1100/2007/EC). The SWRBD is currently regarded as failing to and mid channel bar affected. downstream locations, significantly reducing the direct downstream locations, significantly reducing the direct downstream locations, significantly reducing the direct meet the 40% silver eel escapement management target landtake of in‐channel habitat. landtake of in‐channel habitat. landtake of in‐channel habitat. stipulated by the regulations. Significant monitoring of fish has been undertaken at Hinkley Point B which is 0.5km outside of the Parrett transitional water body in the estuary. Fyke netting has been undertaken at Huntspill in the lower section of the Parrett during 2012 and 2013. Species recorded include conger, European eel, cod, Dover sole, sea bass, mullet and some freshwater species Fisheries impact including perch and roach, indicative of significant freshwater flows and tidal flux at this location. All species are likely to be intermittently present depending upon tidal state and prevailing freshwater flow conditions. Twaite shad have been recorded at Hinkley Point B but not in the Parrett water body. No significant impact on passage of migratory fish is envisaged. Due to the wider land take across the channel the option has the most potential to remove fish habitat but this would be a direct and localised impact.

Located within the Parrett transitional water body which is Baseline conditions as Option 1 but risk to Bathing Quality Zone Baseline conditions as Option 1 but risk to Bathing Quality Zone Baseline conditions as Option 1 but risk to Bathing Quality Zone Baseline conditions as Option 1 but risk to Bathing Quality Zone Baseline conditions as Option 1 but risk to Bathing Quality Zone Baseline conditions as Option 1 but risk to Bathing Quality Zone currently assessed as Moderate Potential failing for Ecological reduces as location moves upstream. reduces as location moves upstream. reduces as location moves upstream. reduces as location moves upstream. reduces as location moves upstream. reduces as location moves upstream. This location, which is elements. No significant impacts on water quality are expected This location, which is substantially upstream of the the Bathing This location, which is substantially upstream of the the Bathing substantially upstream of the the Bathing Water Quality Zone, as the barrier will be operated only on surge tides. Water Quality Zone, is expected to have a reduced impact Water Quality Zone, is expected to have a reduced impact is expected to have a reduced impact compared with other compared with other downstream options. compared with other downstream options. downstream options. The site is also located approx. 12km upstream of an important Potential localised impact during closure as barrier is Bathing Water Quality Zone in Burnham on Sea which is immediately downstream of the Chilton Trinity STW outfall Water quality impact currently not meeting EU water quality targets. While no significant impact is expected, option 1 is the nearest to the Bathing Water Quality Zone and therefore has the highest risk of impacting the Bathing Water area during construction or operation.

River Parrett at this location falls within the Severn Estuary Location 2 is approx. 0.7km upstream of the Severn Estuary Location 3 is approx. 1km upstream of the Severn Estuary SAC, Location 4 is approx. 1.3km upstream of the Severn Estuary Location 5 is approx. 2.3km upstream of the Severn Estuary Location 6 is approx. 3km upstream of the Severn Estuary SAC, Location 7 is approx. 4.2km upstream of the Severn Estuary SAC, SPA and Ramsar site (Natura 2000 site) and the SAC, SPA and Ramsar site and Bridgwater Bay SSSI. Bridgwater SPA and Ramsar site and Bridgwater Bay SSSI. Bridgwater Bay SAC, SPA and Ramsar site and Bridgwater Bay SSSI. Bridgwater SAC, SPA and Ramsar site and Bridgwater Bay SSSI. Bridgwater SPA and Ramsar site and Bridgwater Bay SSSI. Bridgwater Bay SAC, SPA and Ramsar site and Bridgwater Bay SSSI. Bridgwater Bridgwater Bay SSSI. Bridgwater Bay NNR approx. 8km Bay NNR approx. 10km downstream. Exmoor and Quantocks NNR approx. 11km downstream. Exmoor and Quantocks Bay NNR approx. 11.3km downstream. Exmoor and Quantocks Bay NNR approx. 12.3km downstream. Exmoor and Quantocks NNR approx. 13km downstream. Exmoor and Quantocks Bay NNR approx. 14.2km downstream. Exmoor and Quantocks downstream. Exmoor and Quantocks Oakwoods SAC approx. Oakwoods SAC approx. 13km south west ‐ Barbastelle and Oakwoods SAC approx. 13km SW ‐ Barbastelle and Bechstein’s Oakwoods SAC approx. 13km SW ‐ Barbastelle and Bechstein’s Oakwoods SAC approx. 14km W ‐ Barbastelle and Bechstein’s Oakwoods SAC approx. 14km W ‐ Barbastelle and Bechstein’s Oakwoods SAC approx. 14km W ‐ Barbastelle and Bechstein’s 11km south west ‐ Barbastelle and Bechstein’s bats have been Bechstein’s bats have been known to forage as far as the Steart bats have been known to forage as far as the Steart Peninsula. bats have been known to forage as far as the Steart Peninsula. bats have been known to forage as far as the Steart Peninsula. bats have been known to forage as far as the Steart Peninsula. bats have been known to forage as far as the Steart Peninsula. known to forage as far as the Steart Peninsula. Somerset Levels Peninsula. Somerset Levels and Moors SPA and Ramsar site is Somerset Levels and Moors SPA and Ramsar site is approx. 7km Somerset Levels and Moors SPA and Ramsar site is approx. 7km Somerset Levels and Moors SPA and Ramsar site is approx. 8km Somerset Levels and Moors SPA and Ramsar site is approx. 9km Somerset Levels and Moors SPA and Ramsar site is approx. and Moors SPA and Ramsar site is approx. 7km east and is approx. 7km east and is hydraulically linked via the River east and is hydraulically linked via the River Parrett. east and is hydraulically linked via the River Parrett. NE and is hydraulically linked via the River Parrett. NE and is hydraulically linked via the River Parrett. 10km NE and is hydraulically linked via the River Parrett. hydraulically linked via the River Parrett. Parrett. Option 3 is outwith any designated sites. There is potential for Option 4 is outwith any designated sites. There is potential for Option 5 is outwith any designated sites. Less risk to changes to Option 6 is outwith any designated sites. Less risk of any Option 7 is outwith any designated sites. Less risk of any Option 1 would have direct land take on the Severn Estuary Option 2 is outwith any designated sites. There is potential for any changes to geomorphology downstream to affect habitats any changes to geomorphology downstream to affect habitats geomorphology downstream affecting habitats with Natura changes to geomorphology downstream to affect habitats with changes to geomorphology downstream to affect habitats with Natura 2000 site and the Bridgwater Bay SSSI habitat features, any changes to geomorphology downstream to affect habitats with Natura 2000 site and SSSI. with Natura 2000 site and SSSI. 2000 site and SSSI. Natura 2000 site and SSSI. Natura 2000 site and SSSI. both temporary during construction and permanent, which with Natura 2000 site and SSSI. While outside designated areas there remains potential for While outside designated areas there remains potential for While outside designated areas there remains potential for While outside designated areas there remains potential for While outside designated areas there remains potential for would have to be mitigated or compensated. Effects on While outside designated areas there remains potential for effects on migratory fish from habitat loss, increased turbidity, effects on migratory fish from habitat loss, increased turbidity, effects on migratory fish from habitat loss, increased turbidity, effects on migratory fish from habitat loss, increased turbidity, effects on migratory fish from habitat loss, increased turbidity, Impact on biodiversity/statutory migratory fish from habitat loss, increased turbidity, effects on migratory fish from habitat loss, increased turbidity, disturbance and changes to water chemistry that form part of disturbance and changes to water chemistry that form part of disturbance and changes to water chemistry that form part of disturbance and changes to water chemistry that form part of disturbance and changes to water chemistry that form part of disturbance and changes to water chemistry that form part of disturbance and changes to water chemistry that form part of the Severn Estuary populations. the Severn Estuary populations. the Severn Estuary populations. the Severn Estuary populations. the Severn Estuary populations. features the Severn Estuary populations. the Severn Estuary populations. Risk to any impact on water levels of the Somerset Levels and Risk to any impact on water levels of the Somerset Levels and Risk to any impact on water levels of the Somerset Levels and Risk to any impact on water levels of the Somerset Levels and Risk to any impact on water levels of the Severn Levels and Less risk to any impact on water levels of the Somerset Levels Risk to any impact on water levels of the Somerset Levels and Moors SPA and Ramsar during a surge event will gradually Moors SPA and Ramsar will gradually increase as the location Moors SPA and Ramsar will gradually increase as the location Moors SPA and Ramsar will gradually increase as the location Moors SPA and Ramsar will gradually increase as the location and Moors SPA and Ramsar at this downstream location during Moors SPA and Ramsar during a surge event will gradually increase as the location moves upstream. moves upstream. moves upstream. moves upstream but is not considered likely to be significant. moves upstream. operation during a surge event. increase as the location moves upstream. Chilton Trinity Ponds Local Wildlife Site is located on the left Chilton Trinity Ponds Local Wildlife Site is located nearby, bank; permanent footprint unlikely to be within site but although the permanent impact will not impact the site. construction impacts would need to be carefully managed to minimise impact on associated species. Site is designated for complex of ponds, reed beds, trees and scrub with rich bird and invertebrate populations.

Clear views from public footpath BW10/12, River Parrett Trail Clear views from public footpath BW10/12, River Parrett Trail Clear views from public footpath BW10/12, River Parrett Trail Clear views from public footpath BW10/12, River Parrett Trail Clear views from public footpath BW10/12, River Parrett Trail Clear views from public footpath BW10/12, River Parrett Trail Clear views from public footpath BW10/12, River Parrett Trail and proposed England Coast Path which run along the left and proposed England Coast Path which run along the left bank and proposed England Coast Path which run along the left and proposed England Coast Path which run along the left and proposed England Coast Path which run along the left and proposed England Coast Path which run along the left and proposed England Coast Path which run along the left bank bank, and public footpath and proposed England Coast Path and public footpath BW28/10 which and proposed England bank. There are long reaching views along the bank so the bank. There are long reaching views along the bank so the bank. There are long reaching views along the bank so the bank. There are long reaching views along the bank so the and public footpath which runs along the right bank. which run along the right bank. There are long reaching views Coast Path which run along the right bank. There are long structure would be clearly visible from a distance along this structure would be clearly visible from a distance along this structure would be clearly visible from a distance along this structure would be clearly visible from a distance along this Residential flats on Linham Road, Bridgwater have clear, direct along the bank so the structure would be clearly visible from a reaching views along the bank so the structure would be clearly route. There will be a less noticeable effect on views from other route. There will be a less noticeable effect on views from other route. There will be a less noticeable effect on views from other route. There will be a less noticeable effect on views from other views toward site 7 (approx. 50m). As flats have main living distance along this route. visible from a distance along this route. There will be a less nearby PRoWs as field boundaries are well vegetated with nearby PRoWs as field boundaries are well vegetated with nearby PRoWs as field boundaries are well vegetated with nearby PRoWs as field boundaries are well vegetated with spaces on upper storeys, there are views from an elevated The village of Pawlett lies 600m north east of site 1, from which noticeable effect on views from other nearby PRoWs as field hedgerows and trees which limit views. hedgerows and trees which limit views. hedgerows and trees which limit views. hedgerows and trees which limit views. position from main living area windows. there will be distant views. Brickyard Farm, Keward Farm and boundaries are well vegetated with hedgerows and trees which A small group of houses on the A38 in Dunball have views There are some industrial buildings near Dunball, the A38 and Site 5 is 200m from residential properties in Chilton Trinity and Site 6 is 400m from residential properties in Chilton Trinity and There are some industrial/business units on the right bank at Gaunt’s Farm are approx. 250m from the site. limit views. toward site 3 (approx. 200m). railway line at 300‐500m however indoor workers, road and 200m from Chilton Trinity Fishing Lakes. 500m from Chilton Trinity Fishing Lakes. approx. 50m and Western Way crosses the River Parrett Visual/landscape impact Overall this option will create a moderate impact. A small group of houses on the A38 in Dunball have views There are some industrial buildings near Dunball, the A38 and rail users are not considered sensitive receptors. There are some industrial/business units on the right bank at There are some industrial/business units on the right bank at adjacent to the site; however indoor workers and road users toward site 2 from a distance (approx. 1km). There are some railway line at approx. 250m however indoor workers, road and Overall this option will create a moderate impact. approx. 200m however indoor workers are not considered approx. 150m however indoor workers are not considered are not considered sensitive receptors. industrial buildings near Dunball at approx. 500m, however rail users are not considered sensitive receptors. sensitive receptors. sensitive receptors. Treatment works approx. 100m south are Overall this option will create a moderate impact. indoor workers are not considered sensitive receptors. Overall this option will create a moderate impact. Overall this option will create a moderate impact. well screened. The landscape impact is likely to be less intrusive in the area Overall this option will create a moderate impact. due to the existing industrial/commercial nature of the area. Overall this option will create a moderate impact.

River Parrett Trail follows left bank of river (BW10/12). River Parrett Trail follows left bank of river (BW10/12). River Parrett Trail follows left bank of river. Agricultural land River Parrett Trail follows left bank of river. Agricultural land River Parrett Trail follows left bank of river. Industrial Park on River Parrett Trail follows left bank of river. Agricultural land Location 7 is on the immediate outskirts of the north east of Footpath BW27/12 follows right bank of river. Footpath BW27/12 follows right bank of river. Agricultural land dominates land use on both river banks. Access via A38 and B‐ dominates land use on both river banks. Access via A38 and B‐ right bank of river. Series of lakes and drains on the right bank and sewage works on left bank of river and business park on Bridgwater, adjacent to A39 ring road. Relatively built up area Mostly surrounded by agricultural land. Village of Pawlett and Dunball Industrial Estate dominate right bank; agricultural roads / farm tracks. No significant impact envisaged; see also roads / farm tracks. No significant impact envisaged; see also and the village of Chilton Trinity approx. 600m west (Local right. Access via A38 & A39. No significant impact envisaged; with housing estates and a waste disposal site on the left bank approx. 1km north east. land on left bank. Access off M5 and A38 then B‐roads and farm Visual/Landscape Impact. Visual/Landscape Impact. Wildlife Site). Access via A38 and B‐roads. No significant impact see also Visual/Landscape Impact. and industrial estate on the right bank. River Parrett Trail Recreational impact Access via B‐roads and farm tracks. tracks. No significant impact envisaged; see also envisaged; see also Visual/Landscape Impact. follows left bank of river and there is a public footpath on right No significant impact envisaged; see also Visual/Landscape Visual/Landscape Impact. bank. However, no significant impact envisaged; see also Impact. Visual/Landscape Impact.

Listed buildings in Pawlett. No other statutory or non‐statutory Motte with two baileys immediately east of Bristol Road, Down No statutory or non‐statutory designations in vicinity or nearby. No statutory or non‐statutory designations in vicinity or nearby. Several listed buildings in Chilton Trinity (approx. 600m west of No statutory or non‐statutory designations in vicinity or nearby. Number of listed buildings in Bridgwater but unlikely to be designations in vicinity or nearby. Scheduled monument End – Scheduled monument approx. 1km north‐east ‐ neither Scheduled monuments approx. 800m north and 1.5km south‐ Scheduled monuments approx. 1.1km north and 1.5km south‐ Location 5). Horsey medieval settlement immediately north of Scheduled Monument approx. 1.6km east although separated affected. Scheduled Monument approx. 2km north‐east approx. 2km south‐east would not be affected. Potential would be affected. No other statutory or non‐statutory east, neither would not be affected. Many non‐statutory east, neither would not be affected. Potential impacts to Board's Farm – Scheduled Monument approx. 1.8km east by Industrial Park so unlikely to affect setting/views. Potential although separated by Industrial Park so unlikely to affect impacts to unknown archaeological interest in footprint and designations in vicinity or nearby. Potential impacts to heritage assets within the Study Area listed on the Somerset unknown archaeological interest in footprint and working although separated by Industrial Park so unlikely to affect impacts to unknown archaeological interest in footprint and setting/views. Potential impacts to unknown archaeological working areas. Reduced flood risk to heritage assets upstream. unknown archaeological interest in footprint and working HER, however it is anticipated that the impact would not be areas. Reduced flood risk to heritage assets upstream; heritage setting/views. Potential impacts to unknown archaeological working areas. Reduced flood risk to heritage assets upstream; interest in footprint and working areas. Reduced flood risk to Heritage impact areas. Reduced flood risk to heritage assets upstream; heritage significant. Potential impacts to unknown archaeological assets downstream would not benefit from additional interest in footprint and working areas. Reduced flood risk to heritage assets downstream would not benefit from additional heritage assets upstream; heritage assets downstream would assets downstream would not benefit from additional interest in footprint and working areas. Reduced flood risk to protection but risk would not be increased. heritage assets upstream; heritage assets downstream would protection but risk would not be increased. not benefit from additional protection but risk would not be protection but risk would not be increased. heritage assets upstream; heritage assets downstream would not benefit from additional protection but risk would not be increased. not benefit from additional protection but risk would not be increased. increased.

Other than overhead HV cables and pylons nearby on the right No strategic services in the area. Therefore no significant No strategic services in the area. Therefore no significant No strategic services in the area. Therefore no significant Foul and potable water mains offset to the side of the right Foul and potable water mains crossing under river channel Significant number of services in vicinity (HV elec, potable bank no strategic services in the area. Therefore no significant impact anticipated. impact anticipated. impact anticipated. hand bank otherwise no strategic services in the area. immediately downstream otherwise no strategic services in the water, foul water, & telecomms) with a FW rising main crossing impact anticipated. A bridge crossing is being considered in this section, although Downstream of Chilton Trinity STW outfall hence some Downstream of Chilton Trinity STW outfall hence some Downstream of Chilton Trinity STW outfall hence some area. under the river channel just downstream. High likelihood of Long distance downstream and past KSD outfall so unlikely to any potential conflict may be mitigated by modifying the potential interface with treated effluent discharge, etc potential interface with treated effluent discharge, etc potential interface with treated effluent discharge, etc Upstream of Chilton Trinity STW outfall hence no interface with service diversions and temporary protection measures to Impact on strategic interface with Chilton Trinity STW outfall re: treated effluent location of barrier. treated effluent discharge, etc accommodate the barrier construction ‐ however this could be infrastructure (STW, roads, discharge, etc. Long distance downstream and past KSD outfall so unlikely to minimised by slight adjustment in location to suit. mains, etc) interface with Chilton Trinity STW outfall re: treated effluent Upstream of Chilton Trinity STW outfall hence no interface discharge, etc. with treated effluent discharge, etc

Limits the amount of raising of flood embankments and walls It is circa 2.2km to Option 1. Initial assessment of barrier It is circa 0.9km to Option 2. Initial assessment of barrier It is circa 0.4km to Option 3. Initial assessment of barrier It is circa 1.6km to Option 4. Initial assessment of barrier It is circa 0.4km to Option 5. Initial assessment of barrier It is circa 1.2km to Option 6 . Initial assessment of barrier upstream of it ‐ circa 2.2km to Option 2 & 6.7km to Option 7. closure shows downstream water levels (and hence flood risk) closure shows downstream water levels (and hence flood risk) closure shows downstream water levels (and hence flood risk) closure shows downstream water levels (and hence flood risk) closure shows downstream water levels (and hence flood risk) closure shows downstream water levels (and hence flood risk) However initial assessment of barrier closure shows raised circa 5km (interpolated) downstream, for which part of raised circa 4km (interpolated) downstream, for which most of raised circa 4km (interpolated) downstream, for which most of raised circa 3km (interpolated) downstream, for which the raised circa 3km (interpolated) downstream, for which the raised circa 2.2km downstream, for which the mitigation of downstream water levels (and hence flood risk) raised more the mitigation of embankment raising would be incorporated in the mitigation of embankment raising would be incorporated in the mitigation of embankment raising would be incorporated in mitigation of embankment raising would be incorporated in mitigation of embankment raising would be incorporated in embankment raising would be incorporated in downstream than 7.6km downstream, for which the mitigation of downstream embankment raising required in any case. downstream embankment raising required in any case. downstream embankment raising required in any case. downstream embankment raising required in any case. downstream embankment raising required in any case. embankment raising required in any case. Downstream defence raising embankment raising significantly offsets the upstream benefit. Defence raising through Dunball would be complex. Defence raising through Dunball would be complex. Defence raising through Dunball would be complex. Bank raising on the right hand bank to the Premier Inn would It has the benefit of being able to tie into the adjacent high be difficult due to very limit space and proximity to existing requirements ground of Pawlett Hill on the right hand bank relatively easily commercial and residential property. when considering potential future sea level rise and raising of Defence raising through Dunball would be complex. flood defences using an adaptive approach.

Sufficient upstream storage for the Parrett fluvial flows Sufficient upstream storage for the Parrett fluvial flows Sufficient upstream storage demonstrated through earlier Sufficient upstream storage demonstrated through earlier Sufficient upstream storage demonstrated through earlier Sufficient upstream storage demonstrated through earlier Sufficient upstream storage demonstrated through earlier demonstrated through earlier modelling for all Options. demonstrated through earlier modelling for all Options. modelling. modelling. modelling. modelling. modelling. Available volume reduces as the Options move upstream. Discharge from the KSD will also be stored upstream when Discharge from the KSD will also be stored upstream when barrier is closed. This may be a significant factor as the Upstream storage barrier is closed. This may be a significant factor as the frequency of closure increases in the future. frequency of closure increases in the future.

Reduced upstream water levels during large tidal events will Reduced upstream water levels during large tidal events will Reduced upstream water levels during large tidal events will Reduced upstream water levels during large tidal events will Reduced upstream water levels during large tidal events will Reduced upstream water levels during large tidal events will Reduced upstream water levels during large tidal events will Impact on land drainage allow greater volume of discharge from drainage outfalls and allow greater volume of discharge from drainage outfalls and allow greater volume of discharge from upstream drainage allow greater volume of discharge from upstream drainage allow greater volume of discharge from upstream drainage allow greater volume of discharge from upstream drainage allow greater volume of discharge from upstream drainage the KSD during a tidal cycle. the KSD during a tidal cycle. outfalls. There may be a minor negative impact on the outfalls. There may be a minor negative impact on the outfalls. There may be a minor negative impact on the outfalls. There may be a minor negative impact on the outfalls. (outfalls) & Kings Sedgemoor discharge from the KSD due to slighly increased tide levels discharge from the KSD due to slighly increased tide levels discharge from the KSD due to slighly increased tide levels discharge from the KSD due to slighly increased tide levels Drain outfall downstream of the closed barrier downstream of the closed barrier downstream of the closed barrier downstream of the closed barrier

Significant berm/sand bar on right hand side of channel will be Significant berm/sand bar on right hand side of channel will be On right hand side of channel in front of 150m long abutment Accreted area on right hand side of barrier opening will require Narrower channel with increased flow velocities will have Narrower channel with increased flow velocities will have Narrowest channel amongst options with increased flow as per existing or potentially accrete over time . This will as per existing or potentially accrete over time . This will sediment deposition in front of KSD outfall likely to increase regular flushing and dredging to keep gate sill relatively free reduced dredging requirements. reduced dredging requirements. velocities is expected to have the least requirement for require regular flushing and dredging to keep gate sill relatively require regular flushing and dredging to keep gate sill relatively with increased regular dredging required to keep gravity sluices from circa 0.5m to 2m depth of sediment for gate operation. Risk of damage from larger commercial vessels passing through Risk of damage from larger commercial vessels passing through maintenance dredging. free from circa 2m depth of sediment for gate operation. free from circa 1m depth of sediment for gate operation. clear. Risk of damage from larger commercial vessels passing through the barrier avoided. the barrier avoided. Risk of damage from larger commercial vessels passing through With larger commercial vessels passing through the barrier With larger commercial vessels passing through the barrier Accreted area on right hand side of barrier opening will require the barrier significantly reduced relative to options 1 and 2 due Moderate size barrier will require commensurate maintenance Moderate size barrier will require commensurate maintenance the barrier avoided. there is generally greater damage to the barrier structure, there is generally greater damage to the barrier structure, regular flushing and dredging to keep gate sill relatively free to reduced commercial traffic. inputs and gate & MEICA refurbishment /replacement works inputs and gate & MEICA refurbishment /replacement works Relatively small size barrier will require commensurate navigation protective measures, etc which requires more navigation protective measures, etc which requires more from circa 2m depth of sediment for gate operation. Large size barrier will require significant maintenance inputs over time still relatively significant. over time still relatively significant. maintenance inputs and gate & MEICA refurbishment Level of maintenance maintence than where navigation is limited to small maintence than where navigation is limited to small Risk of damage from larger commercial vessels passing through and large gate & MEICA refurbishment/ replacement works /replacement works over time still relatively significant. recreational craft. recreational craft. the barrier significantly reduced relative to options 1 and 2 due over time. Large complex gate will require significant maintenance inputs Large complex gate will require significant maintenance inputs to reduced commercial traffic. and large gate & MEICA refurbishment replacement works over and large gate & MEICA refurbishment replacement works over Large size barrier will require significant maintenance inputs time. time. and large gate & MEICA refurbishment replacement works over time. 13 1 of 2 Option Option 1 Option 2 Option 3 Option 4 Option 5 Option 6 Option 7

Assessment Criteria Opposite Pawlett Hill Downstream of Dunball Wharf Upstream of KSD Outfall Downstream of Express Park Express Park downstream of Chilton Trinity STW Express Park upstream of Chilton Trinity STW Downstream of A39 Bridge Minor‐moderate operational complexity introduced through Moderate operational complexity introduced through the need Benefit from having barrier controlling upstream Parrett and Although slightly further upstream there is still a potential Higher flow velocities in narrower channel will potentially Higher flow velocities in narrower channel will potentially Higher flow velocities in narrower channel will potentially the need to manage larger commercial traffic and fluvial flow to manage larger commercial traffic and fluvial flow influenced Tone tidal influence at same location where KSD outfall benefit from having barrier controlling upstream Parrett and create operational issues when opening and closing the barrier create operational issues when opening and closing the barrier create operational issues when opening and closing the barrier influenced by the KSD discharge. by the KSD discharge. Potential to jointly manage flood controlled ‐ potential for joint flood operations centre for both Tone tidal influence in close proximity to location where KSD gate but may assist in keeping the cill clear of silt. gate but may assist in keeping the cill clear of silt. gate but may assist in keeping the cill clear of silt. Operational requirements operations for the Parret/Tone and KSD. catchments. outfall controlled ‐ potential for joint flood operations centre for both catchments.

Access during construction will be limited to existing narrow Operational access to the barrier on right hand bank, where Operational access to the barrier on right hand bank, where Operational access to the barrier on right hand bank, where Operational access good with right bank access directly off Operational access reasonable with right bank access directly Access very good with potential to use existing highway bridge lanes or will require construction of temporary roadway. barrier control building is likely to be located, is relatively close barrier control building is likely to be located, would be the barrier control building is likely to be located, would be the from Express Park access road and NHS car park. On left bank off A38 Britol Road and circa 300m length of access track. On maintenance access road on left bank and via industrial estate Operational access to the barrier on right hand bank, where to Dunball with circa 300m length of access road from same as for the KSD outfall which is directly off the northbound same as for the KSD outfall which is directly off the northbound relatively short access with circa 150m long access track off left bank relatively short access with circa 100m long access on right bank. barrier control building is likely to be located, is fairly remote Bridgwater Business Park and links to the wider primary road A38 at Dunball. On left hand bank access is more remote with A38 at Dunball. Adjacent land has permission for a north bound Squares Road, Chilton Trinity. track from northern end of Chilton Trinity STW (dependent on Adjacent A39 road bridge allows relatively easy vehicle and with circa 600m length of access road off River Road, Pawlett . network (however will need ability for 24/7 access through access off Chinehorn Rhyne using new access track circa 700m in/out access. Planning guidance ensures development does The size of barrier at this location may introduce the need for a 24/7 access through STW). pedestrian access for operatives to cross river and reach barrier On left hand bank access is even more remote with access off Park). On left hand bank access is more remote with access off long. not prejudice the delivery of a barrier in this location.. On left man access service tunnel beneath the barrier sill, although The size of barrier at this location may introduce the need for a plant and equipment located on the opposite bank/abutment. Access Chinehorn Drove using farm access tracks circa 2km long via Chinehorn Rhyne using new access track circa 300m long. The size of barrier at this location may introduce the need for a hand bank access is more remote with access off Chinehorn time to drive from one side to the other via the A39 road bridge man access service tunnel beneath the barrier sill, although Hallicks Farm. The size of barrier at this location may introduce the need for a man access service tunnel beneath the barrier sill. Rhyne using new access track circa 600m long. (circa 4km) is 10 to 15 minutes. time to drive from one side to the other via the A39 road bridge The size of barrier at this location may introduce the need for a man access service tunnel beneath the barrier sill The size of barrier at this location may introduce the need for a (circa 3km) is 8 to 12 minutes. man access service tunnel beneath the barrier sill. man access service tunnel beneath the barrier sill.

Competent foundation strata/bedrock circa 16 to 26 mbgl (low Competent foundation strata/bedrock circa 26 mbgl (low Competent foundation strata/bedrock circa 17 to 24 mbgl Competent foundation strata/bedrock circa 24 to 25 mbgl (low Competent foundation strata/bedrock circa 10 to 15 mbgl Competent foundation strata/bedrock circa 22 to 28 mbgl (high Competent foundation strata/bedrock circa 10 mbgl (high confidence). confidence). (medium confidence). confidence). (medium confidence). confidence). confidence). No known landfill sites within 500m of proposed location. No known landfill sites within 500m of proposed location. No known landfill sites within 500m of proposed location. No known landfill sites within 500m of proposed location. Location is approximately 200m north of the Saltlands Waste Northern boundary of the Saltlands Waste Disposal Site occurs The Saltlands Waste Disposal Site occurs 40m to the northwest Three historic and two authorised landfill sites occur Three historic and two authorised landfill sites occur Three historic and two authorised landfill sites occur Three historic and two authorised landfill sites occur Disposal Site ‐ as the landfill is located upstream of the site, its approximately 30m south of the site and runs parallel with the of the site and runs parallel with the riverbank downstream. approximately 2km to the east of the area, however, these approximately 2km to the north east of the area, however, approximately 2km to the north of the area, however, these approximately 2.5km to the north of the area, however, these impact on any proposed works is not expected to be significant. riverbank upstream and downstream its impact on any The surface of the landfill is approximately two to three metres would not be expected to impact on any proposed works. these would not be expected to impact on any proposed works. would not be expected to impact on any proposed works. would not be expected to impact on any proposed works. Squares Road landfill is a small historic site which occurs proposed works is potentially significant. higher than the river bank. The narrow strip of land between Geotechnical & approximately 250m to the west and is located at a sufficient Chilton Trinity STW is located 150m south west of the site with the historic landfill site boundary and the River Parrett is geoenvironmental issues distance that it would not be expected to impact on any potential to impact on any proposed works. assumed to be free of landfill for the purposes of this proposed works. assessment. This will need to be verified, with further investigation undertaken as necessary if the option is carried forward.

Barrier and downstream embankments protect areas of Barrier and downstream embankments protect areas of Barrier and downstream embankments protect areas of Barrier and downstream embankments protect areas of Barrier and downstream embankments protect areas of Barrier and downstream embankments protect areas of Barrier and downstream embankments protect areas of existing and proposed residential and commercial existing and proposed residential and commercial existing and proposed residential and commercial existing and proposed residential and commercial existing and proposed residential and commercial existing and proposed residential and commercial existing and proposed residential and commercial development. development. development. development. development. development. development. Isolated location with no direct or indirect contribution to Location provides potential for river crossing as part of a long Unlikely to provide opportunity for road crossing in this Could potentially provide road access across the river as part of Unlikely to provide any opportunities for road crossing given Unlikely to provide any opportunities for road crossing given No wider regeneration benefits. Additional wider regeneration or opportunities to facilitate future term northern by‐pass option. It might also facilitate future location given the complexity of the existing A38 in the vicinity a nothern by‐pass. Also provides opportunities for future that the Express Park is substantially built out and no longer that the Express Park is substantially built out and is no longer appropriate growth. employment and housing development in the area supporting of the KSD. development on the west side of the river. Adjacent to existing easily allows reconfiguration. No immediate development easily allows reconfiguration. No development opportunities on planning/regeneration benefits the wider development of the town. land identified for improving local employment. opportunities on the west side of the river as in close proximity the west side of the river due to the close proximity to Chilton to Chilton Trinity STW and a recently completed housing Trinity STW and a recently completed housing development. development.

Width and configuration of channel allows construction of Width and configuration of channel allows construction of Width and configuration of channel allows construction of Width and configuration of channel allows construction of High flow velocities will be an issue and will have a significant High flow velocities will be an issue and will have a significant Piling and gate placement, etc close to bridge ‐ safe working temporary bypass channel to accomodate commercial temporary bypass channel to accomodate commercial temporary bypass channel to fluvial flood flows and temporary bypass channel to fluvial flood flows and impact on construction methodology. impact on construction methodology. zone ‐ will probably dictate moving barrier location slightly navigation using Dunball Wharf. navigation using Dunball Wharf. construction of barrier gate in single cofferdam. construction of barrier gate in single cofferdam. Maintaining fluvial flood flows will require construction of main Maintaining fluvial flood flows will require construction of main downstream. Main structure & gate constructed in two parts. Main structure & gate constructed in two parts. Although flow velocities high not as significant as further Although flow velocities high not as significant as further structure abutments offline on either side of channel. structure abutments offline on either side of channel. High flow velocities will be an issue and will have a significant Although flow velocities high not as significant as further Although flow velocities high not as significant as further upstream for Options 1 to 3. upstream . Construction of gate sill will be difficult and require Construction of gate sill will be difficult and require impact on construction methodology. upstream for Options 1 to 3. upstream for Options 1 to 3. No significant service diversions envisaged. No significant service diversions envisaged. prefabricated sill to be used as potential solution ‐ tidal prefabricated sill to be used as potential solution ‐ tidal Maintaining fluvial flood flows will require construction of main Significant size and cost of permanent (as well as temporary) Significant size and cost of permanent (as well as temporary) Envisaged that service provision (elec, water, telecomms) Envisaged that service provision (elec, water, telecomms) conditions will mean restricted working time. conditions will mean restricted working time. structure abutments offline on either side of channel. protective measures for barrier as well as navigation safety protective measures for barrier as well as navigation safety would be a relatively short distance from Dunball to the barrier. would be a relatively long distance from Dunball to the barrier. No significant service diversions envisaged. No significant service diversions envisaged. Construction of gate sill will be difficult and require measures due to large vessels using Dunball Wharf. measures due to large vessels using Dunball Wharf. There will be challenges in dealing with dredged material and There will be challenges in dealing with dredged material and Envisaged that service provision (elec, water, telecomms) Envisaged that service provision (elec, water, telecomms) prefabricated sill to be used as potential solution ‐ tidal Construction/buildability Maintaining fluvial flood flows will require construction in 2 Maintaining fluvial flood flows will require construction in 2 its reuse. its reuse. would be over a relatively short distance. would be over a relatively short distance. conditions will mean restricted working time. parts (possibly 3). parts (possibly 3). Adjacent land has permission for a north bound in/out access Need to manage impact from working adjacent to landfill sites. Need to manage impact from working adjacent to landfill sites. Significant service diversions envisaged. No significant service diversions envisaged. No significant service diversions envisaged. which may be used for temporary road to reduce impact on Access for construction will place additional load on existing Access for construction will place additional load on existing Envisaged that service provision (elec, water, telecomms) Envisaged that service provision (elec, water, telecomms) Envisaged that service provision (elec, water, telecomms) existing congested network. network. network. would be over a relatively short distance. would be a significant distance from Pawlett to the barrier. would be a significant distance from Dunball to the barrier. Need to manage impact from working adjacent to landfill sites. Access for construction will place additional load on existing network. Impact on access across the A39 bridge may influence the work at Hinkley Point C.

Capital cost of approx. 107m barrier in range of £65‐75m Capital cost of approx 82m barrier in range of £50‐60m (based Capital cost of approx. 74m barrier in range of £52‐62m (based Capital cost of approx. 74m barrier in range of £45‐55m (based Capital cost of approx. 46m barrier in range of £32‐37m (based Capital cost of approx. 38m barrier in range of £27‐32m (based Capital cost of approx 27m barrier in range of £20‐25m (based Capital cost ‐ barrier (based on Hartel Barrier in Holland as benchmark) on Hartel Barrier as benchmark). on Hartel and Ijssel Barriers as benchmarks plus 150m long on Hartel and Ijssel Barriers as benchmark) . on Hull Barrier and Hartel Barrier as benchmarks). on Hull Barrier and Ipswich Barrier as benchmarks) on Hull Barrier and Ipswich Barrier as benchmarks) Green = less than £30m 20m wide crest closure bank). Amber = £30‐50m Red = more than £50m Capital cost ‐ downstream Capital cost of approx. 7.5km of associated downstream works Capital cost of approx. 6km of associated downstream works in Capital cost of approx. 5km of associated downstream works in Capital cost of approx 5km of associated downstream works in Capital cost of approx 3km of associated downstream works in Capital cost of approx 3.5km of associated downstream works Capital cost of approx 5km of associated downstream works in embankments in range of £13‐16m range of £10‐13m range of £10‐13m range of £10‐13m. range of £7‐10m in range of £7‐10m range of £11‐14m Green = less than £10m Amber = £10‐15m Red = more than £15m Average annual barrier O&M cash cost (based on 1 to 2% of Average annual barrier O&M cash cost (based on 1 to 2% of Average annual barrier O&M cash cost (based on 1 to 2% of Average annual barrier O&M cash cost (based on 1 to 2% of Average annual barrier O&M cash cost (based on 1 to 2% of Average annual barrier O&M cash cost (based on 1 to 2% of Average annual barrier O&M cash cost (based on 1 to 2% of capital cost over 100 year design life) = £0.65m to £1.5m. capital cost over 100 year design life) = £0.5m to £1.2m. capital cost over 100 year design life) = £0.5m to £1.2m. capital cost over 100 year design life) = £0.5m to £1.1m. capital cost over 100 year design life) = £0.3m to £0.7m. capital cost over 100 year design life) = £0.3m to £0.6m. capital cost over 100 year design life) = £0.2m to £0.5m. Average annual maintenance cost for d/s embankments as per Average annual maintenance cost for d/s embankments as per Average annual maintenance cost for d/s embankments as per Average annual maintenance cost for d/s embankments as per Average annual maintenance cost for d/s embankments as per Average annual maintenance cost for d/s embankments as per Average annual maintenance cost for d/s embankments as per Whole life cost existing. existing. existing. existing. existing. existing. existing.

HIGHEST CAPITAL AND WHOLE LIFE COST. HIGH CAPITAL AND WHOLE LIFE COST. HIGH CAPITAL AND WHOLE LIFE COST. LOWEST CAPITAL AND WHOLE LIFE COSTS. MEDIUM CAPITAL AND WHOLE LIFE COSTS. RISKS TO DELIVERY MEDIUM CAPITAL AND WHOLE LIFE COSTS . LOWER CAPITAL AND WHOLE LIFE COSTS . SIGNIFICANT ADVERSE IMPACTS THAT ADD RISK TO POTENTIAL IMPACT ON NAVIGATION AND UNSTABLE RIVER BED IN THIS UNSTABLE RIVER BED IN THIS LOCATION MAKES THIS A HIGH TECHNICAL RISKS APPEAR MANAGEABLE . OVERALL RATING APPEAR TO BE MANAGEABLE. RISKS TO DELIVERY APPEAR TO BE MANAGEABLE. RISKS TO DELIVERY APPEAR TO BE MANAGEABLE. DELIVERY LOCATION MAKE THIS A HIGH RISK OPTION RISK OPTION PERCEIVED TO BRING THE LEAST BENEFIT TO REGENERATION.

14 2 of 2 3.3 Short list option selection The options appraisal process requires that options which appear unlikely to be beneficial, are not taken forward for more detailed assessment. Further assessment can concentrate on those options which are more likely to be practical and have significant benefit. In making the assessment about which options are taken forward we have to judge if the options are technically feasible, if they are likely to have significant environmental impacts and if they offer value for money and are affordable.

Our assessment is that although there are some advantages associated with Locations 1 and 3, these are far outweighed by the disadvantages and these two locations should not be taken forward to the short list. The disadvantages are largely driven by the size of the barrier and the associated capital and maintenance costs, the location near to environmentally designated sites, the impact on navigation to Dunball Wharf and the potential for significant geomorphological impacts in the River Parrett.

Location 2 does have some advantages in terms of its relationship with the KSD, larger storage capacity and potential to include a road crossing. Should additional external funding be available, for example through wider private sector development, and delivery be within the project timescale, this location could be viable if navigation issues could be resolved.

Location 4 is smaller in scale overall than the structures that would be required at 2 and 3, it avoids the issues with navigation to Dunball Wharf and it offers some potential for facilitating future development to the north of Bridgwater. Therefore although the costs are relatively high and there could be significant geomorphological impacts it is taken forward to short list assessment.

Locations 5, 6 and 7 are narrower, the barrier is smaller and therefore cheaper to construct, maintain and operate. Access is generally good to these sites although there are some spatial constraints that would impact on construction and the arrangement of the permanent works. The proximity to a historic landfill on the west bank, services crossing the river channel and the lack of space to improve defences downstream of the barrier locations are all disadvantages of these locations. These three locations will be taken forward to the short list assessment stage.

4.0 WHAT HAPPENS NEXT?

We are undertaking a more detailed assessment of Locations 2 and 4 – 7 including the downstream defences. This work includes hydraulic modelling, geotechnical assessment, concept design, environmental assessment, costing and economic assessment. We are planning to consult on the emerging outcomes of this work in September 2016 before we decide on which option to take forward for funding approval and legal consents.

In the meantime if you have comments or questions about the project please e-mail them to [email protected]

15