Strategy Approval Report

Authority Strategy IMSW000584 Reference

Defra / WAG LDW WXS003E/001A/001A Number FSOD F/1011/0135

Promoting Authority Environment Agency – South West Region

Strategy Name Parrett Estuary Flood Risk Management Strategy

View of Parrett Estuary during 1981 flood from Stockland Bristol north west to Highbridge

Date June 2010

Version 7

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StAR for Parrett Estuary Flood Risk Management Strategy

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* Version 7 – Changes only to Executive Summary

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Environment Agency – SW Region PEFRMS June 2010

CONTENTS

1 Executive Summary ...... 1 1.1 Introduction and Background ...... 1 1.2 Problem ...... 2 1.3 Options ...... 2 1.4 Recommended Strategy ...... 2 1.5 Economic case and outcome measures ...... 3 1.6 Environmental and social considerations ...... 3 1.7 Risks...... 4 1.8 Implementation ...... 4 1.9 Contributions and funding ...... 5 1.10 Status ...... 5 1.11 Recommendations...... 5 2 Business case...... 2 2.1 Introduction and Background ...... 2 2.2 Problem ...... 5 2.3 Options Considered ...... 10 2.4 Economics...... 13 2.5 Environmental and Social Issues ...... 18 2.6 Choice of Preferred Option ...... 22 2.7 Other Considerations...... 27 3 Strategy Plan...... 30

TABLES Table 1.1 Economic case and outcome measures on FMU basis Table 1.2 Strategy main risks Table 1.3 Cost of Strategy 2011 / 2014 / 2017 Table 2.1 Flood Management Units Table 2.2 Designations Table 2.3 Strategy Objectives Parrett Estuary Flood Risk Management Strategy Table 2.4 Significant Flood Events Table 2.5 Properties at risk Table 2.6 Summary of flood risk management options Table 2.7 Short listed options - Cannington / Huntspill and Pawlett FMUs Table 2.8 Summary of Potential Options – Bridgwater West and East FMUs Table 2.9 Summary of whole life cost and PV cost Table 2.10 Cost of Strategy 2011 / 2014 / 2017 Table 2.11 Preferred strategic options for each FMU – damages (£k) Table 2.12 Not Used Table 2.13 Environmental and social impacts affecting option selection Table 2.14 Summary of Option Assessment Table 2.15 Recommended overall preferred option and outcome measures Table 2.16 Environmental impacts and opportunities Table 2.17 Outcome Measure 1 Economic Benefits to 2017 CSR

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Table 2.18 Outcome Measure 2 Number of households moved out of any flood probability category to a lower one to 2017 CSR Table 2.19 Outcome Measure 2b Number of households moved from the very significant or significant flood probability (high risk) category to the moderate or low category (low risk) to 2017 CSR Table 2.20 Final Outcome Measures to 2017 CSR Table 2.21 Strategy main risks Table 3.1 Comparison against strategy objectives Table 3.2 Cannington outfalls programme of work Table 3.3 Cannington embankments programme of work Table 3.4 Bridgwater programme of work Table 3.5 Spend profile

FIGURES Figure 2.1 Parrett fluvial catchment Figure 2.2 Restriction of floodplain by M5 Figure 2.3 Important points of environmental interest Figure 2.4 Outline plan of 1981 flood extent (affecting PEFRMS area) Figure 2.5a Cannington and Bridgwater West- Current standards of defence and standards of protection Figure 2.5b Bridgwater East - Current standards of defence and standards of protection Figure 2.5c Huntspill and Pawlett FMU - Current standards of defence and standards of protection Figure 2.6a Standards of defence through time accounting for sea level rise, current condition and deterioration if no action taken – Cannington / Bridgwater West FMUs. Figure 2.6b Standards of defence through time accounting for sea level rise, current condition and deterioration if no action taken – Bridgwater East FMU Figure 2.6c Standards of defence through time accounting for sea level rise, current condition and deterioration if no action taken – Pawlett & Huntspill FMU Figure 2.7 Potential managed realignment options Figure 3.1 Summary of Our Plan Figure 3.2 Preferred strategic option Figure 3.3 Vulnerability plans (sequence of requirement for improvement work, if defences maintained as today)

APPENDICES Appendix A Figures Appendix B Option development Appendix C Economics Appendix D Sedgemoor District Council commitment Appendix E Flood risk analysis Appendix F Rate of deterioration Appendix G Geomorphology Appendix H Strategic Environmental Assessment H1 SEA – Non Technical Summary H2 SEA H3 SEA – Appendices H4 Responses H5 Statement of Case H6 Consultation Brochure Appendix J Carbon footprinting Appendix K NRG approval history

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1 Executive Summary

SUBMISSION TO OBTAIN STRATEGY APPROVAL South West Region: Parrett Estuary Flood Risk Management Strategy (PEFRMS) Approval Value: £ 200M Sponsoring Director: Director of Operations APPROVAL ROUTE Section A9 of the Financial Scheme of Delegation states that, for whole life costs in a Flood Risk Management Strategy Agency Board approval is required in excess of £50,000,000. Route: National Capital Programme Manager Miles Jordan National Review Group Ken Allison Regional Director Richard Cresswell Director of Operations David Jordan Director of Finance Mark McLaughlin Chief Executive Paul Leinster Board Defra /WAG required (Natura 2000) 1.1 Introduction and Background 1.1.1 This report presents a 100 year flood risk management strategy for the Parrett Estuary through and downstream of Bridgwater, Somerset. It covers the flood cells that are only within the Parrett. Those flood cells at the estuary mouth will be considered within the Severn Estuary Flood Risk Management Strategy (SEFRMS) to be submitted for approval in 2010. Refer to key plan. 1.1.2 We instigated this strategy as many properties alongside the estuary currently receive a low standard of protection. It is timed to ensure that it is reflected in Sedgemoor District Council’s (SDC) Local Development Framework. As a consequence the Council has set a tariff for developer contributions within its supplementary planning guidance. 1.1.3 The Parrett Estuary is part of the Severn Estuary/Bristol Channel system with one of the highest tidal ranges in the world of up to 14m and is navigable to Bridgwater. More than 11,000 properties and 3,000 hectares of agricultural land are located within the River Parrett tidal floodplain, which makes up our strategy area. Most of the properties at risk lie within Bridgwater, including local emergency facilities. 1.1.4 The defences are located immediately adjacent to the estuary throughout the area and comprise earth embankments and walls. The land behind is generally level at approximately 6m AOD and defence levels range typically between 7.5m and 8.5m AOD. Flood warning and flood awareness systems are in place, but do not cover all those at risk if the defences breach. 1.1.5 We divided the strategy area into four hydraulically independent flood management units (FMUs), divided by topographic watersheds. The key plan shows the boundaries. 1.1.6 We considered National and European policy including the Water Framework and Habitats Directives. We drew on the following previous studies, strategies and projects: Shoreline Management Plan (Bridgwater Bay to Bideford Bay) (1998)(recommended Observe and Monitor in conjunction with possibly retreating the defence line); Coastal Habitat Management Plan (CHaMP) (2006), The Parrett Tidal Sluice Appraisal (2006); The Parrett Catchment Flood Management Plan (CFMP) consultation draft (2008); Severn Estuary FRM Strategy (in progress due late 2010); Steart Coastal Management Project (on going). 1.1.7 The recommended works will be implemented under Section 147 of the Water Resources Act 1991, using powers under Section 165. New works fall under the Town and 1 Environment Agency – SW Region PEFRMS June 2010

Country Planning (Environmental Impact Assessment)(England and Wales) Regulations 1999 (SI293) or under Environmental Impact assessment (Land Drainage Improvement Works) Regulations 1999 SI 1783 as amended by SI 2005/1399 and SI 2006/618. 1.1.8 Our main strategy aim is to provide a plan for the sustainable management of flood risk to people, property and the environment over the next 100 years that: a) reduces risk to life and protects and enhances residents’ well-being; b) protects property and existing infrastructure; c) protects and enhances biodiversity, cultural heritage and landscape. 1.2 Problem 1.2.1 This area is exceptionally vulnerable to breach risk as peak tidal levels i.e. events up to 1 in 200 probability (0.5%AEP) over the next 100 years will be 2 to 3m above land levels and there is little high ground to which to retreat. Breaches would lead to rapid, widespread, deep flooding similar to a dam-break situation. This is a particular concern in Bridgwater where hundreds of properties lie immediately behind the defences. Overtopping without breach in the rural areas is less of a concern, where approximately 200mm depth of overtopping is tolerable before breaching. 1.2.2 The current standard of protection (at onset of overtopping) varies between 1 in 5 (short lengths downstream of Bridgwater) and greater than 1 in 200 probability (0.5% AEP) (various lengths throughout the strategy area). The actual flood risk to property is typically less than this as property is either set back from the defences, or is in an urban area with a higher standard of protection. The flood risk experienced by residential property ranges between less than 1 in 20 and more than 1 in 200 (5% to 0.5%AEP). 1120 residential and 43 commercial properties have an existing risk of less than 1 in 75 (1.3% AEP). If we do not act, sea level rise will increase flood risk, and 10,864 residential and 943 non-residential properties will be unserviceable by 2108 due to frequency of flooding. This point is reached when repeated flood damage exceeds the current value of the property. Roads and primary infrastructure such as the distribution network out of Hinkley Point Power Station also lie in the tidal floodplain. 1.2.3 We will improve 4 outfalls and short lengths of highly vulnerable banks at Cannington under a Framework for Action during summer 2010. We assessed the damages assuming these works are in place. 1.2.4 46ha of SPA habitat will be lost from our strategy area due to coastal squeeze over the next 100 years if we maintain the current defence lines. (This is part of the 2000ha to 3500ha of habitat replacement required for the whole of the Severn Estuary.) 1.3 Options 1.3.1 From a longer list of options we considered the following: do nothing; do minimum (i.e. reactive repair to today’s levels), set-back banks/managed realignment in rural areas; upgrading existing defences; surge barrier; and flood warning and awareness. 1.4 Recommended Strategy 1.4.1 Main actions within the strategy are: a) Strengthen and upgrade the defences holding the line at all locations until a tidal barrier for Bridgwater is operational (these works will not be obsolete once a barrier is in place). b) Construct a tidal barrier for Bridgwater between 2030 and 2050 (current optimum 2046). c) Managed realignment at Pawlett Hams after construction of tidal barrier. We may control tidal inflows to create specific habitats or reduce risks of sudden erosion. d) Provide replacement habitat for coastal squeeze and BAP habitat. e) Mitigate losses of freshwater habitat during upgrading of defences in the area. f) Improve and direct our existing flood warning systems on the basis of the flood risk mapping generated by the strategy, to reduce risk to life

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1.4.2 Flood risk standards a) Minimum standard of protection against breach in 1 in 200 chance (0.5% AEP) b) Minimum standard of against overtopping is 1 in 50 chance (2% AEP) c) Flood risk to property is 1 in 200 chance (0.5% AEP) d) We aim to achieve the above standards by 2017. The rate of degradation of the defences and the actual rate of sea level rise will dictate the times at which we intervene.

1.4.3 The main benefits of the preferred options are: a) Reduced flood risk (as compared to doing nothing) to at least 2,115 residential properties and 137 commercial properties by 2017 increasing to 10,864 residential properties and 943 commercial properties in 2108. These properties would otherwise have been made unserviceable (written off) over the Strategy period but instead will have a flood risk of less frequent than 1:200 (0.5%AEP). b) Realignment of defences at Pawlett Hams (circa 2046) will allow up to 387 ha of inter- tidal habitat to be created, which far outweighs any losses caused by holding the line elsewhere and will contribute 341ha to the Severn Estuary targets. c) Substantial opportunities to increase freshwater habitats and populations of some protected/RDB (red book data species)/BAP freshwater species during defence upgrading programme, e.g. freshwater invertebrates. Conservatively the economic valuation of these enhancements has not been included in the analysis, because the decision is not sensitive to this element. d) Continued navigation of the Parrett Estuary and commercial use of Dunball Wharf. e) 6 Scheduled Monuments, 59 listed buildings and a number of sites in the historic monument record will be at reduced flood risk. f) Protection of infrastructure including roads, primary emergency services and primary electrical grid. 1.5 Economic case and outcome measures 1.5.1 The following table summarises the present value costs, benefits and benefit cost ratios of the preferred strategic plan over the next 100 years for each FMU. The figures presented take account of timing of investment to accommodate the impacts of climate change. Bridgwater West and East have been considered jointly in the table below as the provision of the preferred solution (a tidal barrier) influences both flood management units equally.

Table 1.1 – Economic case on FMU basis* Bridgwater Bridgwater Huntspill & Location Cannington West East Pawlett Proposed SoP (minimum) 1 in 50 (2%AEP) overtopping 1 in 200 (0.5%AEP) breach

Present Value costs £k £29,000 £18,000 £32,600 Present Value benefits £k £343,000 £1,700,000 £184,000 Net present value £k £314,000 £1,680,000 £151,000 Benefit cost ratio 11.8 95.4 5.6 Number of residential properties benefiting 1700 1138(W ) + 7266(E) =8404 786

Cost per residential property £k £17 £2 £42 *assuming Cannington Outfalls and urgent banks project is completed 2010 1.6 Environmental and social considerations 1.6.1 The area supports a large area of coastal habitats designated within the Severn Estuary Natura 2000 complex. We have prepared a Strategic Environmental Assessment (SEA) together with a Strategic Environmental Proposal, Opportunities and Risk Plan. Refer to Figure 6.3 of the SEA. 3 Environment Agency – SW Region PEFRMS June 2010

1.6.2 The strategy, and the required Habitats Regulations Assessment (HRA), is supported by Natural England (see Appendix H). The HRA found there will be an adverse effect on the internationally designated sites, where 7ha of habitat fronting the defences will be lost in the short to medium term and a further 39ha will be lost in the long term due to coastal squeeze. The strategy acceptability depends on the timely provision of compensatory habitat for coastal squeeze. We will provide this through the Steart habitat creation project in the short term and managed realignment at Pawlett Hams in the longer term, which will contribute 341ha of habitat to the Regional Habitat Creation programme, specifically contributing to the habitat requirements of the wider Severn Estuary. Defra accepts the HRA and is satisfied that there are Imperative Reasons of Overriding Public Interest (IROPI) to pursue the Strategy (refer to Appendix H). 1.6.3 Our consultation on the draft strategy and SEA included; a brochure sent to 1300 homes, local press features, local drop-in surgeries, contacts with Parish Councils and Bridgwater Town Council, letters to landowners on Pawlett Hams, detailed strategy document in 2 main libraries and our offices, advert and brochure on our website and we fully consulted with Statutory stakeholders through the SEA. The majority of responses were either positive or neutral. 1.6.4 Our proposed strategy is our environmentally preferred approach to achieving our targets and vision. 1.7 Risks Table 1.2 - Strategy main risks Risk Key Mitigation The options are unaffected by SLR. Revised predictions will only change Certainty of sea level rise the timing of the requirements. Strategy reviews should focus on this (SLR) estimate. High risk Low risk Global economic climate Would likely alter benefit cost ratios but ranking of options would remain influencing costs the same. High risk Medium risk Over design event Ensure major incident plan is in place. Continue flood warning practices. Low risk Low risk 1) Construction of barrier brought forward with external contributions to Political drivers change assist development. Work closely with Sedgemoor District Council. policy 2) Value of environmental replacement habitat reduced in favour of Medium risk preserving farmland. Review policy and update strategy as required. Low risk (as there is time for strategy to adapt) Only one option i.e. Bridgwater Bay lagoon, has a potential hydraulic Severn Estuary tidal impact, whilst others have habitat needs. We will check invest power solutions programme at regular strategy reviews. Medium risk Low risk 1.8 Implementation 1.8.1 We propose the following short term programme of work packages: a) By 2011 i. Cannington Outfalls. Framework for Action project - due for construction 2010. ii. Cannington embankments (2 short urgent sections) b) By 2014 i. Improve standard of protection (SoP) of Cannington FMU defences to minimum of 1:50 (2%AEP) c) By 2017 i. Improve SoP of short lengths of more vulnerable Bridgwater FMU’s defences Flood warning systems will be updated in keeping with national initiatives.

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Table 1.3 – Cost of Strategy Projects 2011 / 2014 / 2017 Cannington Huntspill Bridgwater and Outfalls & Other Banks Urgent Banks Banks Pawlett Totals Item Outcome Measures 2011 2014 2017 Defra Outcome Measures OM1 11.80 11.80 95.40 - - Defra Outcome Measures OM2 1440 865 756 - - Defra Outcome Measures OM2b 0 536 756 - - Defra Outcome Measures OM3 0 0 0 - - Defra Outcome Measures OM5 0.3 0 0 - - To 2017 2011 (£k) 2014(£k) 2017 (£k) (£k) (£k) Costs pre StAR 0 0 0 - 0 Agency costs (including surveys) 77 329 64 - 470 Preliminary costs 0 0 0 - 0 Consultants fees 173 1070 208 - 1451 Construction costs 491 7530 1470 - 9491 Environmental enhancement costs 20 308 60 - 388 Compensation 73 385 75 - 533 Contingency – 95%ile (represents - 60 % of project) 145 5780 1130 7055 Inflation @ 5% per annum 6 5240 1650 - 6896 Total capital cost to 2017 985 20600 4650 - 26300 Post 2017 Future construction costs including (after 2017) 0 48400 39000 75200 163000 Maintenance costs over period of strategy 0 3000 13000 2000 18000 Whole life cash cost (including 200000 maintenance but without inflation) 979 66800 55000 77200 (Note 2) Notes: 1. For a full breakdown of costs refer to Appendix C- Economics. 2. Total excludes inflation and rounded to nearest £m 1.9 Contributions and funding 1.9.1 All projects are expected to qualify for FDGiA. 1.9.2 New developments in Bridgwater are the most significant source of contributions. There are no existing dominant beneficiaries in the area. We have aligned our strategy with SDC's Local Development Framework, which will put planning obligations on major developments for flood defence provision. This will raise allocated funds of £9m, i.e. £1700 per new house (approximately 40%, of the cost of the proposed barrier in Bridgwater). 1.10 Status 1.10.1 The strategy appraisal has confirmed the policy recommendations from the Parrett CFMP and the emerging North Devon and Somerset SMP. 1.10.2 The strategy plans to deliver compensatory habitat for coastal squeeze to satisfy the Habitats Directive. Defra has not objected to these planned actions. 1.10.3 Implementing this strategy will make provision for sea level rise and provide continued or improved protection for at least 11,000 properties against tidal flooding over the next 100 years and will provide at least a 1:200 (0.5%) standard of protection to property. 1.10.4 Natural England has provided a letter of support for this strategy. 1.11 Recommendations 1.11.1 It is recommended that the Parrett Estuary Flood Risk Management Strategy is approved under A9 scheme of delegation, at a whole life cash cost (excluding inflation, but including an optimism bias allowance of 60%) of £200 million (PV cost £80million).

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Directors Briefing Paper Region: South West Project Executive: John Taberham Function: Flood defence Project Manager: Graham Quarrier

Parrett Estuary Flood Risk Management Strategy Title: Code: IMSW000584 Strategy

NEECA NCF Cost Black & Veatch N/A N/A Consultant: Contractor: Consultant:

Gradual degradation of 40km raised defences (2-3m above ground levels) The Problem: provides an increasing risk of breach, especially with sea level rise

11,000 homes within the theoretical undefended People at risk : floodplain of between 5% and 0.5% risk. 1120 homes Probability of exposure: at significant risk in the existing defended situation i.e. Consequence of exposure: >1.3% Environmental resources at risk: Severn SPA and cSAC subject to coastal squeeze if Probability of exposure: defences are maintained Consequence of exposure: Assets at risk from flooding: General infrastructure, mainly in Bridgwater eg main Probability of exposure: roads, hospitals, schools, power lines. Consequence of exposure:

Maintain and improve current line of defence until between 2030 and 2050. Defences then retreated at Pawlett Hams Description of proposed strategy: (387ha BAP habitat replacement) and surge barrier installed to protect Bridgwater. Elsewhere, we will continue to strengthen and hold the line. 2621 properties have flood risk reduced by 2017. 11,000 Outcome for people at risk: properties maintained at 0.5% risk at end of 100 years Provision for new inter-tidal habitat exceeds losses. Outcome for environmental Freshwater habitat losses will be mitigated during re- resources at risk: construction of floodbanks Outcome for assets at risk: Flood risk to properties improved to 0.5%

Costs (PVc): Benefits: Ave. B: C ratio: (100 year life inc. £80m £ 2,200m 27.5 (PVb) (PVb/PVc) maintenance) Incremental Range4.24 Whole life cost NPV: £ 2,120m £200m B: C ratio: to 53.27 (cash value):

Choice of Preferred See Description of Strategy. Satisfies all objectives Option:

Total cost for which approval is sought: £ 200 Million (incl. £75 Million contingency)

Delivery programme: 1) Upgrade 4 outfalls by 2011 and 2) Upgrade and strengthen Cannington and Bridgwater FMU defences by 2017.

Are funds available for the delivery of this programme? Yes, projects to 2017 have OM score > 2.5

External Natural England agrees with the strategy. Sedgemoor District Council is using approvals: this Strategy to inform its Local Development Framework.

Defra Defra has agreed the Habitats Regulations Assessment and Imperative Reasons approval: of Overriding Public Interest (IROPI) (March 2010).

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2 Business case 2.1 Introduction and Background

Purpose of report and methodology

2.1.1 The PEFRMS identifies the preferred strategic tidal flood risk management approach for the Parrett Estuary through and downstream of Bridgwater, Somerset. 2.1.2 Steart and Burnham-on-Sea flood cells are included in the Severn Estuary Flood Risk Management Strategy (SEFRMS) (due in 2010), as they form part of the Severn Estuary frontage. However, actions at Steart have the potential to impact on the Parrett Estuary. Therefore, we have studied the Steart Flood Management Unit in outline and have ensured that this information is fully integrated within the SEFRMS. 2.1.3 This appraisal has been undertaken in accordance with the Defra FCDPAG series of documents and the “Supplementary Notes to Operating Authorities”.

Legislative Framework and Previous History 2.1.4 The Environment Agency has permissive powers for managing the flood risk from designated main rivers and the sea under Section 165 of the Water Resources Act 1991. 2.1.5 The management of tidal flooding is a significant issue for Sedgemoor District Council as a substantial part of the Council area is within the tidal floodplain. The Council requires strategic FRM solutions to allow Bridgwater to develop safely. We worked with Sedgemoor District Council (SDC) to align our strategy with the Council's Local Development Framework. Under the Framework, SDC introduced planning obligations for those new developments that rely on flood defences. SDC have agreed (full Council meeting 16/9/09) to levy a tariff on new houses built within the flood plain. The new housing allocation in the area will make up approximately 40% of the total number of dwellings protected by the tidal barrier. Therefore, the tariff is set to raise £9.84m (40%) of the estimated cost (calculated to include an optimism bias allowance). This equates to approximately £1,700 per new house. 2.1.6 We have developed this strategy considering information obtained and to implement policies and plans derived from the following: a) Bridgwater Bay to Bideford Bay Shoreline Management Plan, Halcrow (1998). The SMP recommended to “Observe and Monitor (in conjunction with possibly retreating the existing defence line)”. b) North Devon and Somerset Shoreline Management Plan (Hartland Point to Anchor Head), Halcrow, due 2010. We are concurring with their emerging policies. c) Parrett Catchment Flood Management Plan (CFMP) 2004 (update nearing completion). Considers the need for a strategy to deal with sea level rise either by improvement of banks, or by means of a tide excluding structure. We are now meeting this need with our PEFRMS. The CFMP boundary meets our own strategy boundary to ensure that we have a comprehensive coverage of flood defence issues. d) Severn Estuary Coastal Habitat Management Plan (2007) The CHaMP estimated inter- tidal habitat losses of approximately 2000ha over the whole Severn Estuary. We are obliged to compensate for at least the 46ha loss attributed to the Parrett Estuary. e) Severn Estuary Flood Risk Management Strategy, (due 2010). There are many overlaps with this strategy (including shared hydraulic and environmental data), most notably assessing the future of the Steart Peninsula. We have developed this strategy in close liaison with the Severn Estuary Strategy team. f) Steart Coastal Management Project – In response to high level targets and proposals for managed realignment as compensation for the Bristol Deep Water Container Terminal, the habitat replacement opportunities are now being assessed under the current Steart Coastal Management Project. This is being undertaken incorporating the findings from the SEFRMS and PEFRMS investigations.

2 Environment Agency – SW Region PEFRMS June 2010 g) The Parrett Tidal Sluice Technical Review, (February 2006). Presents an assessment of the feasibility of tidal exclusion structure options. We have produced it in parallel with this strategy to obtain an early understanding of the likely operating regime and its impacts on development. h) Severn Tidal Power Feasibility Study (ongoing). This feasibility study is ongoing and the draft short list of options for consideration includes a lagoon enclosing Bridgwater Bay. Proposals for consultation are currently programmed to take place in summer 2010 and if a scheme were to go ahead in Bridgwater Bay it would be at least 8 years before it would be operational. No attempt has been made to consider the implications of this within this strategy, but this would need to be assessed in future reviews of the strategy. Location 2.1.7 The strategy area is located on the reach of the River Parrett where tide levels dictate the flood risk. Flood risk dominance changes from fluvial to tidal immediately upstream of Bridgwater at the M5 motorway crossing (refer to Figures 2.1 and 2.2 Appendix A). Acknowledging this the SMP upstream boundary is set at this crossing and this is reflected in our strategy. 2.1.8 The boundaries relating to the strategy are shown on the Key Plan. The strategy area is the area presently within the Environment Agency’s defined floodplain as published on our website between the M5 bridge over the River Parrett upstream of Bridgwater and the mouth of the estuary at Burnham-on-Sea and Stert Point. 2.1.9 The study area includes a wider area beyond the strategy area, which may either be directly affected by strategy proposals, or can directly affect the proposals. For example wading birds using the strategy area will often roost some distance inland outside the strategy area, but within the wider study area. 2.1.10 There are even wider influences, such as migrating birds and an inflow of fine marine sediments, which we have also considered in this appraisal.

Description of area 2.1.11 The area is largely grade 3 agricultural land. Most of the 11,000 homes protected are located in Bridgwater. 1,300 are located in the smaller communities including Combwich, Pawlett, Huntspill and Highbridge. 2.1.12 Rural areas are defended from tidal inundation by earth embankments and a combination of earth embankments and walls defend Bridgwater. All defences follow both banks of the estuary. The defence crests are typically 7.5m AOD outside Bridgwater and 8.4m AOD through Bridgwater. The level of a 1:200 probability event today in central Bridgwater would be 8.2mAOD and the same event would be 8mAOD at Combwich. Natural ground levels are fairly flat, typically 6m AOD, only rising to higher ground close to strategy boundaries. The tidal range in the Parrett Estuary is typically 11m. 2.1.13 Flood risk is from surge tides. Fluvial flows are limited by the capacity of the fluvial system upstream and do not influence extreme water levels in the estuary. 2.1.14 All tidal defences and associated assets in the area are the responsibility of the Environment Agency. The Parrett IDB generally maintains and operates drainage channels and control structures in the defended tidal floodplain. 2.1.15 We have divided the strategy area into four independent Flood Management Units (FMUs) plus Steart FMU as listed in Table 2.1. 2.1.16 We considered ground levels and flooding mechanisms to identify these unit areas. Each FMU is at risk from a common hazard (e.g. failure within a particular length of bank) and is broadly suitable for a common solution. 2.1.17 Each FMU is bounded by high ground and is geographically discrete within the order of tidal flood events influencing our business case.

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Table 2.1 – Flood Management Units Ref Name Characteristics Existing defences - Banks and walls Large agricultural area (mainly grade 3, some grade 2 at FMU boundary) Can Cannington Connectivity with Steart at Combwich (via 50m of low land) Includes part of north-west Bridgwater Bridgwater Existing defences - Banks and walls BrW West Large urban area and some agricultural land (grade 1 to 3 – mostly 3) Existing defences - Banks and walls Bridgwater BrE Large urban area and some agricultural land (grade 3) East Connectivity with Pawlett and Huntspill in extreme events Existing defences – Banks Pawlett and P&H Rural (grade 3 with small area of grade 2 land) Huntspill Connectivity with Bridgwater East (NB. Estuary frontage considered but will be approved under the Severn Estuary Flood Risk Management Strategy.) St Steart Existing defences – Shingle ridge, walls and banks Rural Connectivity with Cannington and Bridgwater (left bank) at Combwich Designations 2.1.18 Environmental designations and constraints are indicated on Figure 2.3 in Appendix A and tabulated below:

Table 2.2 – Designations Designation Feature Severn Estuary Special Protection Area (SPA) Waterfowl – saline habitat Severn Estuary candidate Special Area of Conservation (cSAC, Migratory fish – saline habitat boundary as SPA) Severn Estuary Ramsar site, (boundary as SPA) Waterfowl, fish and estuarine invertebrates – saline habitat Bridgwater Bay Site of Special Scientific Interest (SSSI; Inter tidal habitats, plus grazing boundary as SPA). In addition Berrow Dunes SSSI fringes the marsh, freshwater and brackish Study Area to the northwest of Burnham-on-Sea. ditches. Bridgwater Bay National Nature Reserve (NNR) Waterfowl, widgeon – saline habitat Somerset Levels and Moors Special Protection Area Freshwater habitat

Physical Constraints 2.1.19 Below is a summary of what we have found to be the main physical constraints. Refer also to Figure 2.3 in Appendix A and Section 2.6.2 for particular environmental and social constraints. a) High ground is found at the margins of the strategy area, which means that to retreat development or defences would not be straightforward. b) Ground levels are typically between 1.5m and 2.5m below the level of the tidal defences. c) The M5 motorway forms a physical barrier, as demonstrated in the 1981 flood. d) The strategy area is crossed by 3 lines of primary infrastructure power pylons from Hinkley Point nuclear power station (400kV). e) Lower rural defences which overtop before urban flood defences provide a small amount of attenuation of flood levels in Bridgwater. However, major set back of defences would increase extreme tidal water levels in Bridgwater as a result of the reduction in flow resistance. f) Bridgwater is a statutory port. The limit of navigation is at the first road bridge into Bridgwater approaching from downstream.

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Strategic objectives to be achieved 2.1.20 We developed the following objectives to achieve; sustainable flood risk management, local objectives derived from consultation and the aims of “Create a Better Place”. The resulting objectives are listed in Table 2.3.

Table 2.3 - Strategy Objectives Parrett Estuary Flood Risk Management Strategy No Description

1 Develop an integrated approach for the whole estuary with regard to other studies and strategies. Works will not have damaging effects elsewhere. 2 Reduce flood risk via flood warnings and sustainable defences to minimise risk to life, injury, distress and property damage within the Study Area. 3 Develop a sustainable flood risk management plan for the next 100 years.

4 Provide flood management solutions that: • are technically achievable; • are economically viable; • are compatible with objectives for biodiversity; • are adaptive to climate change, notably sea level rise and increased storminess; • maintain, or enhance, social opportunities, livelihoods, recreation and amenity; and • take account of likely future geomorphological change. 5 Maintain adequate discharge of surface water to the estuary.

6 Manage risks of saline intrusion to wildlife and farming interests.

2.2 Problem 2.2.1 Currently 1,380 residential and 63 non-residential properties are at risk of a 1 in 200 (0.5% AEP) event, of which, 1,120 residential and 43 commercial properties are currently at risk in the 1 in 75 (1.33%AEP) event. Climate change will significantly increase the number of properties at risk. (Refer to Table 2.5).

History of flooding 2.2.2 The Parrett Estuary embankments date back to the 14th century. 2.2.3 Flood defences were repaired and improved in reaction to flood events until the late 1970’s when defences were built in readiness for anticipated tidal events. 2.2.4 Table 2.4 illustrates a history of major flood events in our strategy area.

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Table 2.4 Significant Flood Events Date Comments 1607 Potential tidal wave caused by a sub-Atlantic earthquake, which broke the sea bank at Burnham-On-Sea leading to massive flooding of at least 30 villages and their cattle

destroyed. 28 people were drowned at Huntspill and 26 at Brean, a death toll that was repeated in many other villages.

1798, 1809. These flood events led to reactive repairs and improvement to protect against similar 1875, 1883, event reoccurring. Unfortunately, bigger events continued to occur and overwhelmed the 1903, 1904, improved defences. 1936, 1957, 1963 1974 This tidal flood event triggered the onset of the phased “Parrett in Bridgwater” scheme, which commenced in 1977 to improve the standard of the tidal defences protecting Bridgwater and the majority of the works phases were complete by 1981. 1981 A 1.45m surge coincided with the peak of a modest spring tide and tidal defences overtopped over long lengths of Somerset’s north and west facing coastline. Wave action caused additional problems and structural damage where defences were exposed to open fetches in the Severn Estuary. A large volume of tidal water overtopped the defences and filled the majority of the tidal floodplain of the River Parrett. The seawater flowed back to the M5 motorway, flooding communities and hundreds of hectares of agricultural land. Hundreds of livestock drowned both in open fields and in stock houses, but no people died during the event as the defences did not breach. Fortunately the phased “Parrett in Bridgwater” scheme was largely complete by the time of the 1981 event. As a result in Bridgwater damages were limited to isolated locations only (Figure 2.4).

Existing defences 2.2.5 We implemented a number of schemes during the 1980s and 1990s to provide protection against flood events of a 1 in 100 chance of occurring in any year. The height of the banks are designed to ensure that water flows into agricultural land first rather than towns. 2.2.6 Today the banks and associated structures offer various standards of protection. If we do nothing, by 2017 limited lengths (identified for urgent work) will offer less than 1 in 1 standard of protection (100%AEP). We assessed the standards based on a fragility analysis which accounted for condition (degraded condition/bank shape), crest level and increasing sea level throughout the strategy period to reflect climate change as per Defra 2006 guidelines. The results of which are shown on Figure 2.6.

Probability of flooding and erosion risk 2.2.7 The current standards of protection are summarised in Figure 2.5 in Appendix A. (Note that much of the property is set back from the defences and is at less risk than the defences protecting it due to flood storage on the land between the property and defence). Appendix E provides details on how these figures are determined. These values are current; they do not include sea level rise or other changes that will occur in the future. These standards take account of still water levels, fluvial flows and current condition. 2.2.8 As Figure 2.5 shows most urban areas are directly defended to at least 1 in 100 (1%AEP) on current sea levels although this will decrease with time.

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Table 2.5a – Residential Properties at risk 2008 Properties written off (by 2108)

Flood risk - Residential

FMU Residential

>1 in 20 (5%) >1 in (5%to 1.33%) (0.5% to 0.3%) (0.5%to 0.5%)(0.3%to (1.33% to to 0.5%) (1.33% 1 in 20 to 1 in to in 1 in 20 1 75 1 in 75 to 1 in in 75 to 1 200 in 1 < 1 in 500 in (<0.2%) 500 < 1 1 in 200 to 1 in 333 to200 1 in in 333 1 to333 1 in in 500 1 Cannington 996 105 156 55 27 4120 1,670 Bridgwater West 0 0 0 0 0 4100 1,140 Bridgwater East 0 0 0 0 0 7270 7,270 Huntspill & Pawlett 0 19 104 112 56 915 786 Total Strategy Area 996 124 260 167 83 16400 10,900

Table 2.5b - Commercial Properties at risk 2008 Properties written off (by 2108) Flood risk - Commercial Commercial

FMU >1 in 20 (5%)in 20 >1 (5% 1.33%)(5% to (0.5% to 0.3%) (0.5% to 0.5%) (0.3% to (1.33% to (1.33% to 0.5%) 1 in 20 in 20 to in 1 1 75 1 in 75 to 1 in 200 to in 1 in 75 1 200 < 1 in 500 in (<0.2%) < 1 1 in 200 to in to 200 1 1 in 333 in to 333 1 1 in 500 Cannington 31 3 5 1 0 327 46 Bridgwater West 0 0 0 0 0 443 116 Bridgwater East 0 0 0 0 0 817 696 Huntspill & Pawlett 0 9 15 8 4 93 85 Total Strategy Area 31 12 20 9 4 1680 943

Scope of problem 2.2.9 Table 2.5 details the numbers of properties at risk. Cannington FMU has a significant number of properties at high flood risk. However, there are a number of other assets at risk and these are summarised below. a) Pylon lines from Hinkley Point Nuclear Power Station (400kV). b) 4,380 hectares of agricultural land. c) Parrett Trail which runs the full length of the left bank of the defences. d) Possible buried archaeological remains. e) Burnham-on-Sea beach might suffer additional erosion if flood defence alignments do not allow for sea level rise and relax their line overall. f) Primary emergency facilities e.g. Bridgwater hospital, several doctors surgeries and a police station. g) Education assets including land supporting the land based studies at Bridgwater College, Cannington.

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2.2.10 Our defences will deteriorate to a poor condition over time if no improvement works are made periodically. Refer to Figure 2.6 in Appendix A. 2.2.11 For efficient flood risk management, we have to know when to invest in our defences rather than react after an event. Thus we have used national studies to assess how long this process of deterioration takes for different types of defence in different environments (e.g. National Assessment of Defence Needs and Costs (Risk Assessment for Strategic Planning) [NADNAC (RASP)] condition grade deterioration curves). The defences in the Parrett Estuary have a typical lifespan of 60 years from being newly constructed before major renovation work could be expected. However, they are likely to deteriorate to a poor condition in 35 years. Further details are given in Appendix F. 2.2.12 Current Defra guidance for flood management suggests that sea levels in our strategy area will rise by approximately 105mm by 2025, 354mm by 2055, 550mm by the 2080s and 985mm by 2115, on today’s sea levels. The standard of defence provided by the defences will reduce as a consequence. For example, we calculated that a defence currently providing a level of protection of 0.5% (1:200 chance of being over topped or breached in any year) will provide a standard of 1.3% (1:75) in 50 years time. 2.2.13 Taking the above factors into account we have developed a managed adaptive programme ensuring effective use of full asset value and a realistic, pragmatic approach to implementation. 2.2.14 In the first instance we have assumed a 35 year rolling cycle of work, which reflects the time taken for newly built good defences to deteriorate to a poor condition. Taking sea level rise into account we would see a pattern of standard of protection provision as shown in the following diagram.

SoP

Optimum SoP

yr0 yr 100 Time 2.2.15 However, not all assets at the start each period are in immediate need of upgrading and still have some value in them. No practical, or economically efficient, implementation programme should invest in upgrading defences while they are still adequate. Therefore, in practical terms the implementation will typically be over 5 to 10 years at the start of each period, during which we will upgrade the “next worst” defences until all defences are up to standard. 2.2.16 We must assume that at any point in time at least some part of the defences of each FMU may offer the optimum standard of protection while other parts will offer a higher standard. However, the defences of the FMU as a whole are only as good as the lowest standard. For this reason we assessed damages assuming the optimum standard throughout.

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2.2.17 Costs of the embankment works include for appropriate raising to ensure that the optimum standard is achieved at the end of the 35 year periods. 2.2.18 At present, the outfalls cannot discharge to the estuary during periods of high tide. This is known as tide locking. Rising sea levels could have an adverse impact on this and the effects over the full tidal cycle may lead to longer durations of tide locking in agricultural areas, but will have no measurable impact on flood risk.

Geomorphological considerations: 2.2.19 We have also reviewed how the estuary as a whole will respond to sea level rise, particularly the impact on the more vulnerable areas at the mouth of the estuary. a) Currently the estuary is largely in regime (i.e. the capacity of the channel is just right to accommodate the volume and energy of the tidal water). We would need to ease back the defences by a few metres to maintain a stable regime throughout the estuary in response to sea level rise. b) The Bristol Channel/Severn Estuary and the tidal River Parrett carry a very high silt load which is kept in suspension by the high energy system associated with the high tidal range. Silt can be deposited and saltmarsh is accreting in places where banks are set back from the tidal channel i.e. where the estuary is over-wide compared with that required to pass the tidal prism. We have accounted for these processes together with the natural movement of meanders and pinch points when calculating our standards of protection. Refer to Appendix G for details. c) As sea levels rise, increasing volumes of water in the tidal prism will pass in and out of the estuary with each tide i.e. the tidal prism will increase with time. This will put pressure on the estuary to widen to accommodate it. This is particularly the case at the mouth of the estuary and we must take care to understand the effects of our actions. Burnham-on-Sea beach is a particular concern, as it is especially vulnerable and a mainstay of local employment. Action will be needed if the beach is to be maintained in the long term, although this is not a flood risk management issue as the flood defence at Burnham on Sea offers a high standard of defence and is not at risk of being undermined by erosion . d) Sea level rise will accelerate erosion of Burnham on Sea beach, ie the beach is threatened by sea level rise regardless of what flood risk management options we employ in the Parrett Estuary. SLR presents a greater risk to the beach than our proposed FRM actions. For example removal of all defences at Pawlett may add to the tidal prism by only 5 to 10%. Holding the line would restrict the estuary by a similar amount. We would have options to manage the impact of realignment on the tidal prism eg managed tidal exchange, if required. However, it is likely that any works to maintain the beach at Burnham on Sea as a result of the impact of sea level rise would by default have sufficient design capacity to mitigate for the minor effects of managed realignment on the estuary. The best scenario in respect of erosion of the beach is to provide an increased tidal capacity just sufficient to keep the Parrett in regime with increasing tidal volumes . e) Options exist to throttle the estuary from the side of the channel to reduce the tidal prism and so manage the effects of climate change, but this is high risk in terms of predictability of project outcome in a high silt environment. We would also expect major objections from key stakeholders as the approach would not be consistent with “Making space for water” or the objectives set out by the “Water framework directive”. f) Steart (part of the SEFRMS) is a planned area for habitat creation. The Steart Parrett Estuary defences are not under threat in the short term. Options for habitat creation must be managed in combination with the more influential coastal frontage. These issues are part of the separate habitat creation project. However, in general comment the options at Steart are various, but all will require management. Influences from the PEFRMS options are minimal, especially when put in context with the much greater issue of sea level rise, but will need to be managed along with other factors when designing a scheme at Steart. 9 Environment Agency – SW Region PEFRMS June 2010 g) We have also found, that if the defences downstream of Bridgwater were allowed to breach or be realigned inland, tide levels in Bridgwater would increase due to hydraulically “short cutting” the estuary. This would put many properties at high flood risk. Therefore, realignment options downstream of Bridgwater should not be considered prior to upgrading of the Bridgwater defences. Equally, due to the potential for reflected surge waves off a tidal barrier, we should not install a barrier prior to upgrading defences downstream of Bridgwater. We will consider these issues in tandem as part of our continued geomorphological monitoring and study of the estuary over the next 30 years to ensure that we provide the best outcome based on real observed data. 2.3 Options Considered

Long listed options 2.3.1 Table 2.6 below shows a complete list of options considered. Potentially effective options green and grey (where grey is the baseline).

Table 2.6 – Summary of flood risk management options Name Description 1 Do nothing Undertake no further maintenance or construction work within the catchment. Included as a baseline for comparison during assessment. 2 Do Minimum Carry out work to repair breaches as and when they occur and general maintenance over 100 years, but otherwise allow the standard of defence to deteriorate in line with sea level rise and general “wear and tear”. 3 Off line flood storage Contain flood waters within purpose built storage areas designed to fill at a certain water level in the estuary. Not effective in reducing flood levels of the most vulnerable properties. 4 On line flood Contain floodwaters within the floodplain. Lowers lengths of the existing tidal storage/Attenuation embankment, maintain the existing banks, construct spillways and construct new embankments inland to contain the “ponded” floodwater. Not effective in reducing flood levels of the most vulnerable properties. 5 Optimise existing Redirecting flood flows to low risk areas. This is a flood storage variation on options flood storage 3 and 4 above. Not effective in reducing flood levels of the most vulnerable properties. 6 Flood warning and Issue warnings to allow people to prepare for a flood flood awareness 7 Upgrade banks/Hold Improve the existing banks to either strengthen, or raise them, or both (includes the line to keep pace minor realignment of up to 50m from their present position) with sea level rise.

8 Bridge and weir Replace or modify bridges and weirs to reduce flow constraints. Hydraulic capacity modifications is not a controlling factor. Not effective in reducing flood levels. 9 Land management Change in land use to reduce run off and sediment delivery to the estuary. Runoff from the land is not the cause of flooding. Not effective in reducing flood levels. 10 Sustainable Urban Drainage systems that mimic natural processes, such as allowing water to soak into Drainage System the ground. Runoff from the land is not the cause of flooding. (SUDS) Not effective in reducing flood levels. 11 Set back Reposition the defence line back from the estuary (including possibility of regulated banks/Managed tidal exchange) realignment 12 Barrier Construct a structure across the estuary 13 Dredging Remove sediment from the river bed to If we widen or increase the depth of increase the hydraulic capacity. the channel the surface water level

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Table 2.6 – Summary of flood risk management options Name Description 14 Channel widening Widen the channel to increase hydraulic will largely remain unchanged as it capacity. responds to the tide. Not effective in reducing flood levels. 15 Development control Prevent inappropriate development in the floodplain. Runoff from the land is not the cause of flooding. This is a partial solution to future problems not current issues. 16 Individual property Protect individual buildings or small groups of buildings with flood defences placed protection within the property boundary. Relates to a small number of properties and does not contribute to protection of infrastructure. Not a strategic solution. (At project level this should always be considered). 17 Insurance Compensate for flood damage. Moves risk costs and additional cost to nation in insurance fees. Therefore, not sustainable or justifiable. 18 Hold the line then set Combined option to test optimum approach. back defences 19 Hold the line then Combined option to test optimum approach. install a surge barrier for Bridgwater

Short listed options 2.3.2 We have reviewed each of the short list options to form programmes of work suitable for each FMU that follow a ‘managed, adaptive approach’. To achieve this we decided when , to what level and how we take action. 2.3.3 On this basis we had an unlimited number of options, with different interventions over the strategy period delivering different standards of protection. We developed and applied rules to fix the variables guided by the FCDPAG series. The application of these rules is demonstrated in Appendix B Option development. 2.3.4 We grouped the flood risk issues and types of solution into two groups, namely rural areas and urban areas. These short listed options are summarised in the following sections and further detail of their appraisal is included in Appendix B Option development. Rural FMUs- Cannington / Huntspill and Pawlett FMUs 2.3.5 These are largely rural FMUs where property is set inland from the defences. 2.3.6 Short-term options are limited. If we were to set back the defences here we would “short cut” the estuary and cause tide levels to rise in Bridgwater (up to 150mm) and increase flood risk. However, in the medium to long term, Bridgwater defences will need to be upgraded to keep pace with sea level rise and deterioration of the defences. This may provide an opportunity to set back the defences in Cannington/Huntspill and Pawlett if the impact is accounted for in the upgraded Bridgwater defences. 2.3.7 If the defences are set back, we will also need to consider the potential impact of an additional volume of water flowing in and out of the estuary and whether this could cause erosion problems downstream. These are issues to consider and do not preclude set back options in these FMUs. Figure 2.7 in Appendix A shows the potential line of managed realignment options. 2.3.8 The Parrett Tidal Sluice Technical Review, (February 2006) established that a surge barrier was a good feasible option for tackling the reduction in the standard of the defences in Bridgwater due to the combined effects of their deterioration with time and sea level rise the original freeboard will have been taken up by approximately 2050. The cost of a surge barrier would be lower if it is located closer to Bridgwater than in the wider estuary towards the mouth and is not viable in the rural FMUs. 11 Environment Agency – SW Region PEFRMS June 2010

Table 2.7 – Short listed options - Cannington / Huntspill and Pawlett FMUs Ref Name Description DN Do nothing Do nothing – does not provide benefit, but used as a baseline to assess cost of potential damages. DM Do minimum Repair breaches. Level of protection allowed to deteriorate with sea level rise and worsening condition of the defences. HTL Hold the line (upgrade defences) Maintain the current defence line and upgrade the defences to keep pace with sea level rise and “wear and tear”. HTL/MR - 1)Hold the line (upgrade defences) HTL then set back banks in Pawlett and Huntspill H&P1* then 2) set back banks (managed FMU in tandem with upgrading of Bridgwater realignment) defences. HTL/MR- 1)Hold the line (upgrade defences) As above then set back banks in Pawlett and H&P2* then 2) set back banks (managed Huntspill FMU in tandem with upgrading of realignment) Bridgwater defences. HTL/MR – 1)Hold the line (upgrade defences) As above then set back banks in Cannington FMU C1* then 2) set back banks (managed in tandem with upgrading of Bridgwater defences. realignment)C1 line HTL/MR – 1)Hold the line (upgrade defences) As above then set back banks in Cannington FMU C2* then 2) set back banks (managed in tandem with upgrading of Bridgwater defences. realignment) C2 line HTL/MR – Not used – reference refers to previous internal C3* Environment Agency document. Midway alignment that had no advantages over other alignments but at additional cost. HTL/MR – 1)Hold the line (upgrade defences) As above then set back banks in Cannington FMU C4* then 2) set back banks (managed in tandem with upgrading of Bridgwater defences. realignment)C4 line FW Flood warning Flood warning and awareness *Refer to Figure 2.7 for locations Urban FMUs - Bridgwater West and East FMUs 2.3.9 Property lies immediately behind these defences and a proportion is at immediate risk if the defences are overtopped. Options must reflect the direct nature of this risk. Due to limited land availability set back options are not appropriate here. The barrier has no measurable impact on the rural FMUs.

Table 2.8 – Summary of Potential Options – Bridgwater West and East FMUs Ref Name Description DN Do nothing Do nothing – does not provide benefit, but used as a baseline to assess cost of potential damages. DM Do minimum Repair breaches. Level of protection allowed to deteriorate with sea level rise and worsening condition of the defences. HTL Hold the line (upgrade Maintain the current defence line and upgrade the defences defences) to keep pace with sea level rise and “wear and tear”. HTL/Ba Hold the line (upgrade Hold the line and improve defences until they require defences) then install Barrier significant upgrading then install a surge barrier. Ba Barrier Install a Barrier at the outset. FW Flood warning Flood warning and awareness

Steart FMU 2.3.10 Options for Steart will be presented under the SEFRMS. Identification of projects to 2017 12 Environment Agency – SW Region PEFRMS June 2010

2.3.11 Our appraisal has shown that 4 projects are needed by the end of our 2017 CSR period; a) Cannington outfalls, b) Cannington embankments urgent raising of low lengths, c) Cannington Embankments improvement works; and d) Bridgwater minor improvement works. 2.3.12 Huntspill and Pawlett FMU have defences at a lower than 1 in 50 standard of protection, but only 19 properties have a risk of greater than 1 in 75 (1.33%AEP) of a total number protected of 1206. The outcome measure score is less than 2.5 and has not been considered for early works. However, this will be reviewed after 2017. There will be no contributions from other sources. The justification of these priority projects is further explained in the following sections. The scope of these projects is summarised below. 2.3.13 Cannington outfalls and urgent banks is an ongoing project currently at detailed design stage being carried out under the Framework for Action. The project is to do minimal works to upgrade outfalls and banks in the Cannington FMU, which are in such a poor condition that they are immediately at risk of failure and threaten the protection of at least 1400 residential properties in Bridgwater through “backdoor” flooding. This will improve the risk to all property to at least 1 in 20. As this work is ongoing and will be complete by mid- 2010 our baselines for risk assessments assume this work has been done. 2.3.14 By 2014 we will improve the remaining Cannington embankments to a minimum residual standard of protection of 1 in 50 (2% AEP) (accounting for degradation and sea level rise) by the end of the 35 year programme cycle, increasing the protection to 865 properties. 2.3.15 By 2017 we will then improve low elements of the Bridgwater defences to a minimum residual standard of protection of 1 in 200 (0.5%AEP) (accounting for degradation and sea level rise) by the end of the 35 year programme i.e. 2046. 2.4 Economics Methodology 2.4.1 Outlined below is our approach to the benefit calculations. We have included details in Appendix C. In summary we have: a) Assessed the damages that will occur if we do nothing. Damages are driven by a combination of deteriorating banks and increasing sea levels, leading ultimately to bank breach. b) Considered the range of options available to address embankment and wall deterioration and increasing sea levels. c) Considered in detail if and when works would be required. The underlying principle adopted is to maximise the use of assets and only intervene when the risk of breaching or overtopping becomes high (and therefore economically worthwhile). The rate of deterioration of assets is a critical issue and discussed further in Appendix C. d) Considered what standard of protection is economically justified. A range of different standards have been considered and the benefits and costs associated with the different standards assessed. e) Optimised the choice of option, timing and standard in accordance with the FCDPAG3 decision rule. This is reported in Appendix C.

Benefits have been derived as indicated below: a) Residential and commercial property i. based on standard depth damage data in the Multicoloured Manual ii. land use codes taken, where available, from NPD data iii. includes emergency costs and activities of emergency services, local councils and the Environment Agency 13 Environment Agency – SW Region PEFRMS June 2010

iv. includes an allowance for clean-up of utilities, infrastructure, gardens and outdoor space. v. damage is capped at write-off value of property, set equal to its market value (average residential £190,000 per property). vi. market value of commercial property is estimated based on its rateable value. vii. Risk to life is an issue where flooding is potentially rapid and of depths up to 3m without nearby high ground for refuge. This has been calculated following the guidance within Assessing the Risk to Life from Flooding for Use in Appraisal of flood Risk Management Measures (Defra 2008) . b) Agriculture i. included in accordance with the Multi-Coloured Manual ii. market value of agricultural land is based on local real market values (average taken as £17,500/ha)) c) Roads i. roads are unlikely to suffer frequent tidal flooding and damage is negligible. Therefore, we have not included for this at this strategic level. d) Railways i. damage capped at delays associated with a single major flood event, conservative as viability of railway on present alignment would be brought into question. e) Environmental i. we will need to ensure that for all options conservation requirements can be delivered. Therefore economic damage to the environment has not been quantified. Benefits have been valued, in accordance with Flood and Coastal Erosion Risk Management: Economic Valuation of Environmental Effects August 2007. Costs have been derived as summarised below: a. Price Base 2.4.2 We used 2009 Q1 prices to prepare our cost estimates for all options. The costs include for future operation, maintenance, mitigation and repair costs for a 100 year appraisal period to 2108. These are presented as Present Value (PV) costs. b. Comparison with Form A Costs 2.4.3 The forecast cost incurred in preparation of the strategy is £420k. This is less than the approved Form A budget of £428k. c. Cost Estimates 2.4.4 We determined costs for all options from schedules of rates from recent local schemes. Our references also included studies which costed the protection of Steart Peninsula. We have also compared estimates with those derived from our national unit cost database of out-turn costs. Our estimates are at the lower end of these costs, but this reflects our intention to win spoil from land close to the site and the lack of site constraints. The derived unit capital costs with 60% optimism bias are included in Appendix C - Economics. 2.4.5 We included costs for mitigation of freshwater habitat losses at Pawlett Hams in the construction costs. We have also assumed that borrow pits for spoil could be designed to recreate a suitable freshwater habitat locally. The embankment cost build-up includes a 10% allowance (of base construction cost) specifically for habitat creation in connection with the banks and borrow pits, in addition to reinstatement landscaping and seeding. A further 2% of total cost has been added for other environmental enhancements (as reported in Table 2.10) which can be used in areas beyond the immediate banks and borrow pits but in connection with the works.

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2.4.6 We have included pre-construction professional fees for preparation of the business case, detailed design and associated environmental studies in the first two years for the major improvement schemes. In response to benchmarking against similar projects we have included 40% to allow for contractor’s preliminary items. Professional fees and compensation costs for the construction phase have been estimated based on the nature of the works. 2.4.7 We have included future costs for operations, maintenance and refurbishment over the 100 year period of the strategy. The options and the programme of interventions take account of the effects of sea level rise. 2.4.8 Table 2.9 summarises whole life and present value costs, including 60% optimism bias for all short listed options for the alternative standards. We have determined present values using a 3.5% discount rate – reducing to 3% for years 31-75 and 2.5% thereafter. We have shown AEP values that best demonstrate the range of differential options. Intervals smaller than shown represent small changes in defence level and therefore cost. 2.4.9 The embankment costs include for the rebuilding of the banks on a 35 year cycle to reflect structural deterioration and climate change.

Table 2.9 – Summary of whole life cost and PV cost FMU Option Whole life PV cost (SoP against overtopping) cost (£k) (£k) DM £2,600 £800 HTL 4% £65,000 £27,300 HTL 2.5% £67,400 £28,300 HTL 2% £69,000 £29,000 HTL 1% £73,900 £31,100 HTL 0.5% £76,900 £32,400 HTL/MR – C1 4% £63,800 £27,500 HTL/MR – C1 2.5% £66,200 £28,500 HTL/MR – C1 2% £67,800 £29,200 HTL/MR – C1 1% £72,800 £31,400 Cannington HTL/MR – C1 0.5% £75,700 £32,600 HTL/MR – C2 4% £62,800 £27,600 HTL/MR – C2 2.5% £65,100 £28,600 HTL/MR – C2 2% £66,700 £29,300 HTL/MR – C2 1% £71,500 £31,400 HTL/MR – C2 0.5% £74,400 £32,700 HTL/MR – C4 4% £71,400 £30,600 HTL/MR – C4 2.5% £73,700 £31,600 HTL/MR – C4 2% £75,200 £32,300 HTL/MR – C4 1% £79,800 £34,500 HTL/MR – C4 0.5% £82,600 £35,700 DM £3,200 £1,000 HTL 4% £81,200 £31,400 HTL 2.5% £84,200 £32,500 HTL 2% £86,200 £33,300 HTL 1% £92,400 £35,700 Huntspill & Pawlett HTL 0.5% £96,100 £37,200 HTL/MR – H&P1 4% £73,000 £30,800 HTL/MR – H&P1 2.5% £75,500 £31,900 HTL/MR – H&P1 2% £77,100 £32,600 HTL/MR – H&P1 1% £82,300 £34,900 HTL/MR – H&P1 0.5% £85,300 £36,200 Bridgwater West and DM £2,100 £626 East (combined as HTL £93,514 £24,234 barrier option serves HTL/Ba £53,581 £17,814 both banks) Ba £54,762 £29,580

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2.4.10 Shown below is the cost of the strategy to 2017.

Table 2.10 – Cost of Strategy Projects 2011 / 2014 / 2017 Cannington Huntspill Bridgwater and Outfalls & Other Banks Urgent Banks Banks Pawlett Totals Item Outcome Measures 2011 2014 2017 Defra Outcome Measures OM1 11.80 11.80 95.40 - - Defra Outcome Measures OM2 1440 865 756 - - Defra Outcome Measures OM2b 0 536 756 - - Defra Outcome Measures OM3 0 0 0 - - Defra Outcome Measures OM5 0.3 0 0 - - To 2017 2011 (£k) 2014(£k) 2017 (£k) (£k) (£k) Costs pre StAR 0 0 0 - 0 Agency costs (including surveys) 77 329 64 - 470 Preliminary costs 0 0 0 - 0 Consultants fees 173 1070 208 - 1451 Construction costs 491 7530 1470 - 9491 Environmental enhancement costs 20 308 60 - 388 Compensation 73 385 75 - 533 Contingency – 95%ile (represents - 60 % of project) 145 5780 1130 7055 Inflation @ 5% per annum 6 5240 1650 - 6896 Total capital cost to 2017 985 20600 4650 - 26300 Post 2017 Future construction costs including (after 2017) 0 48400 39000 75200 163000 Maintenance costs over period of strategy 0 3000 13000 2000 18000 Whole life cash cost (including 200000 maintenance but without inflation) 979 66800 55000 77200 (Note 2) Flood frequency 2.4.11 We modelled flood risk and damages using the optimum standard of protection in 2008, 2025, 2055, 2085 and 2108 to take account of rising sea levels and deteriorating defence condition. We based our flood damage analysis on the results of hydraulic modelling at each epoch, using overtopping and breach frequency as derived for each FMU. When damages identified for properties exceed the market value, we have capped the damage value.

Option benefit assessment 2.4.12 The option benefit assessment is based on the avoidance of £2,246 million of damages incurred under the Do nothing Option at Q1 2009 prices. These are based on the premise that eventually an un-repaired breach will develop. Because of the height of the banks and the severity of the flooding, 10,864 residential properties would be written off in the 100 year period. 2.4.13 We considered reductions in calculated damages as a result of flood warning. However, in this area flood warning serves to minimise risk to life, but has little impact on material asset damages as there are few options to protect property but we are able to evacuate if a breach is predicted. 2.4.14 We took a managed adaptive approach to the development of all other options and worked on a 35 year cycle of works reflecting the rate of deterioration of the defences. We assumed that works planned in any 35 year cycle would provide at least a residual acceptable standard of protection by the end of the cycle. We accepted that not all works would be carried out in the first year of a 35 year cycle, but would rather be carried out as a programmed sequence of works within the period. Therefore, defences will have various

16 Environment Agency – SW Region PEFRMS June 2010 standards of protection, but all will provide at least the optimum standard (at the end of their design life), or a higher standard (newer defences will provide a higher standard to allow for deterioration and sea level rise over their design life). To reflect this we programmed benefits on the same 35 year cycle based on provision of the optimum standard of protection (selection of the standard of protection is discussed below).

Selection of Standard of Protection Rural 2.4.15 Our analysis of how the existing flood embankments protect the hinterland has shown that the probability of damage to property is lower than the probability of overtopping of the defences in the rural areas. The modelling has shown that the flood capacity of the hinterland is large and considerable volumes of water are stored before significant damage is caused. 2.4.16 Effective use of this storage volume allowed us to consider lower bank standards of protection than those frequently used in similar circumstances. However if the embankment level is too low the force of overtopping water would lead to a bank breach. The storage volume in the land behind the defences has been assessed based on LiDAR data. A detailed assessment of the strength of the embankment under hydraulic load has been undertaken using guidance within Design of Reinforced Grass Waterways CIRIA. 2.4.17 The selection of the standard of protection is detailed in Appendix C Table C10. The decision process follows PAG3 section 6.2. For both the Cannington and Huntspill & Pawlett flood management units a 2% standard is preferred. A 2% standard scheme (i.e. with banks built and maintained at this level) will protect urban band A properties at least between 1% to 0.3%AEP i.e. within the indicative range. This standard is also required to prevent the risk of breach up to the 0.5% event i.e. the banks will tolerate the overtopping volumes. The small number of rural band D properties will receive better protection than their indicative standard (5% to 40%AEP – ref. FCD PAG3).

Urban 2.4.18 The residual damages are higher in Bridgwater than in rural areas, as Bridgwater does not have a large storage volume and damage commences almost immediately on overtopping. A detailed assessment has shown that currently the standard of protection to Bridgwater is greater than 1 in 200 years. However this service would reduce significantly in the future due to sea level rise to 1 in 25 years by 2055 (without freeboard). The installation of a barrier when required in the future will achieve at least a 1 in 200 year standard of protection. 2.4.19 The PV damages for the preferred strategic options for each FMU are presented in Table 2.12 along with PV damages avoided. Tables C11.1 to C11.3 in Appendix C provide further details.

Table 2.12 – Preferred strategic options for each FMU – damages (£k) FMU Present Value PV Costs Net Present Benefit/Cost Benefits (PVb) Value Ratio Cannington 343,000 29,000 314,000 11.8 Bridgwater West & 1,700,000 18,000 1,80,000 95.4 Bridgwater East

Huntspill & Pawlett 184,000 32,600 151,000 5.6

17 Environment Agency – SW Region PEFRMS June 2010

2.5 Environmental and Social Issues

Strategic Environmental Framework 2.5.1 A SEA has been undertaken in accordance with Environment Agency policy and in agreement with Defra advice that a SEA should be undertaken for all FRM strategies. Further details can be found in the SEA Environmental Report (Appendix H). A Habitats Regulations Assessment (HRA) of the Strategy has also been undertaken. Natural England has provided advice on the HRA and a letter of support confirming that in their view the 100 year strategy and the proposed options included in the five year programme of works are likely to lead to an environmentally acceptable solution (see Appendix H). Defra has confirmed that we have complied with our obligations under the Habitats Regulations (see Appendix H). 2.5.2 The HRA explains how the integrity of the designated sites within and adjacent to the strategy area will be maintained, or where affected mitigation and compensation will be made. This will be further addressed at Scheme Appraisal stage through Environmental Impact Assessments (EIA). 2.5.3 The HRA found there will be an adverse effect on the internationally designated sites, where 7ha of Atlantic salt meadow habitat fronting the defences will be lost in the short to medium term and a further 39ha will be lost in the long term due to coastal squeeze. 2.5.4 We prepared a Statement of Case (SoC) (Appendix H) to demonstrate Reasons of Overriding Public Interest (IROPI), which Defra and Natural England support. This concluded that none of the alternative solutions identified in the PEFRMS could be considered to be sustainable over the long term, or were likely to produce lesser adverse effects than the preferred Strategy. 2.5.5 The SoC also concluded that the preferred strategy is required for Imperative Reasons of Overriding Public Interest (IROPI) as it addresses the unacceptable risk to human health and public safety from an uncontrolled breach of the existing flood defence. 2.5.6 Compensatory measures, estimated to include the provision of at least 46 ha of Atlantic salt meadow before losses from coastal squeeze are incurred, will be delivered in two key phases (refer also to the diagram below): a) 0-30 years - provision of 7 ha Atlantic salt meadow: the project being developed on the Steart Peninsula of approximately 380ha of compensatory habitat (approval has been given for the purchase of land options to compensate for short term losses within the Severn Estuary SPA) As an alternative we could design bank layouts to provide for this compensation requirement. Minor realignment of the Cannington FMU banks will also yield 0.3ha. b) 30-100 years - provision of 39 ha of Atlantic salt meadow: the managed realignment at Pawlett Hams, which will provide 387 ha of intertidal habitat, of which approximately 70% would be Atlantic salt meadow. This is 341ha in excess of the losses due to coastal squeeze.

18 Environment Agency – SW Region PEFRMS June 2010

2.5.7 We developed ten strategic environmental objectives to aid environmental appraisal. These were derived from our own Environmental Vision, national government guidance on SEA and sustainability appraisal and feedback from the consultation process. These objectives are: a) To reduce the risk that flooding poses to human life and communities b) To protect recreation facilities and tourism c) To protect and enhance biodiversity d) To protect and enhance air and mitigate impacts from climate change e) To protect and enhance the water resource f) To protect and enhance land quality g) To protect geomorphological processes i.e maintain a stable regime h) To protect and enhance the landscape character and visual amenity i) To protect existing material assets and infrastructure j) To protect and enhance the historic environment Environmental Constraints, Risks and Opportunities People, property and the built environment 2.5.8 Areas within the strategy are some of the most economically deprived in the country (English Indices of Deprivation 2007 (ID 2007)). One of the main aims of the Sedgemoor Local Plan (1991-2011) is to encourage inward investment and tourism. Public confidence in low flood risks will be important to the success of this plan. Human Health 2.5.9 Existing flood defences protect more than 11,000 homes. In addition, Bridgwater fire station, hospitals and medical centres lie within the floodplain (refer to figure 2.5). Floods would affect the provision of health care services and restrict emergency access. 2.5.10 Access to stretches of the embankment and outfall structures for maintenance is currently difficult in places, especially in areas where the bank is narrow. Safe access will be dealt with at project level. 19 Environment Agency – SW Region PEFRMS June 2010

Habitats 2.5.11 In front of the flood defences habitats are typically sub and inter-tidal mudflats, sandbanks, saltmarsh and reed beds. Landward there is a mix of unimproved, semi- improved and improved grassland and coastal floodplain grazing marsh. 2.5.12 Freshwater habitats affected by the preferred option are not internationally designated, but are nationally important. They will not be under threat for at least 30 years and will be maintained until that time. Mitigation for their loss after that time will be incorporated into preceding neighbouring schemes so that replacement habitat is available at the appropriate time. Species 2.5.13 The rhynes and ditches within the strategy area support an outstanding diversity and quantity of aquatic invertebrates; this is recognised within the Ramsar selection criteria (SEA Appendix C). 2.5.14 There is also a small but important run of salmon into the Parrett as they migrate to their spawning ground in the River Tone. 2.5.15 Protected species known to live in the strategy area include lamprey (Lampetra fluviatillis), sea lamprey (Petromyzon marinus) and European eel (Anguilla anguilla), otter (Lutra lutra) and water vole (Arvicola terrestris) (see SEA Appendix C). There are populations of brown hare (Lepus europaeus; a UK BAP species) on Pawlett Hams and there are badgers throughout the strategy area. 2.5.16 Our preferred option is for realignment at Pawlett Hams, which is designated as cSAC and SPA for its terrestrial features. The change of state from a freshwater habitat to a saline one will not affect these features e.g. over wintering birds. Otherwise species will remain unaffected by our proposals. Recreation and Tourism 2.5.17 The adjoining beach at Burnham-on-Sea is a seasonal tourist attraction, which is a notable source of local income and important to the sustainability of the community. 2.5.18 Combwich Common, to the north of Combwich, is protected as recreational open space and Combwich harbour is now largely recreational. Other recreational pursuits are bird watching, fishing, walking and riding (River Parrett Trail plus other public footpaths and bridleways). Cultural heritage 2.5.19 The range of archaeological sites (302 in total) includes dry land sites (crop marks/ soil marks, earthworks, find spots and settlement sites) and a small number of inter-tidal sites (fish weirs and causeways). A total of 245 listed buildings/structures have also been identified (see Table 4.3 the SEA). However, prehistoric archaeology may be under- represented. 2.5.20 Some of the flood banks are medieval in origin. Channel migration due to sea level rise and/or engineering works might also affect riverside and in-channel archaeological features, such as historic landing places, hards and wrecks, (pers. comm. SCC Archaeologist). 2.5.21 There is a high risk that archaeological sites will encountered during bank works. These would likely be Romano-British, or Medieval. Cost of mitigation has been accounted for. Landscape character 2.5.22 The dominant land use is for agriculture. The majority is grade 3 land, although there are areas of grade 2 land near Pawlett and the Huntspill River (MAGIC 2009 www.magic.gov.uk ). We have listed important features of the local landscape below; further details are given in appended SEA (Section 4.7):

20 Environment Agency – SW Region PEFRMS June 2010 c) ground levels along the coast are typically higher than those further inland, which reflects past inundations and fluctuations in sea level; d) land adjacent to the Parrett Estuary is composed of estuarine alluvium deposits underlain by Liassic and Triassic bedrock; e) soils associated with the alluvium and bedrock are typically clay rich and make up approximately 80% of the strategy area; f) the large volume of sediment carried by the tide has deposited extensive inter-tidal mud flats in the Bay and along the Parrett Estuary; g) a large ebb tide delta, which has formed at the mouth of the Parrett Estuary. The delta represents one of the only areas along the Severn Estuary coastline where unconsolidated material is being actively deposited. Consultation 2.5.23 Consultation has been undertaken throughout preparation of the strategy. Details of the consultation process are presented in the accompanying SEA included as Appendix H. 2.5.24 Feedback from this process has varied between neutral to supportive. The most significant concerns relate to replacement of the freshwater habitat on Pawlett Hams, although there is a general acceptance that this may not be sustainable for its freshwater interests in the face of sea level rise. There is also a concern that there will be erosion of archaeological deposits if managed realignment results in tidal creeks developing in undisturbed substrata. 2.5.25 Sedgemoor District Council adopted the draft Strategy recommendation for its Local Development Framework.

Environmental and social impacts that directly affected the option selection 2.5.26 These impacts are summarised shown on Table 2.13 below along with the main mitigation measures if selected as a management option.

Table 2.13 Environmental and social impacts affecting option selection

Option Option Positive Key Impacts Negative Key impacts Management options Yes/No Main mitigation measures Benefit Natura 2000 Major adverse effect on No - sites. communities. Establish a more Effects on surface/groundwater. natural estuarine Short term effects on freshwater regime. systems. Townscape features would be

Do Nothing Do Nothing lost. Inundation of historic sites/features. - Major adverse effect on No - communities. Effects on surface/groundwater. Loss of intertidal habitat Flooding of Do MinimumDo landscape/townscape.

21 Environment Agency – SW Region PEFRMS June 2010

Table 2.13 Environmental and social impacts affecting option selection

Option Option Positive Key Impacts Negative Key impacts Management options Yes/No Main mitigation measures Improved flood Loss of intertidal habitat. Yes Compensatory habitat. protection – Reduced visual amenity through Summer construction - communities, terrestrial Bridgwater. minimise impact on and freshwater designated site features. biodiversity.

Minor setback at pinch

Hold The The Hold Line points alleviates erosion. Creation of intertidal Potential loss of agricultural Yes Diversions of PRoW. habitat in realigned land, property and PRoW. Construction of surge area. Increased risk of flooding in barrier for Bridgwater. Establish a more Bridgwater. EIA identify surface and natural estuary. Effects on surface/groundwater groundwater regime in realigned area. mitigation. Loss of grazing marsh and Compensatory habitat. freshwater systems. Mitigation measures e.g.

Managed Realignment Managed Inundation of historic archaeological watching sites/features. briefs etc. Improved flood Obstruct fish migration during Yes Impacts on fish migration protection – Bridgwater, extreme events. assessed at project level. freshwater and Potential landscape impact. Liaison with Sedgemoor Tidal Tidal Surge Surge terrestrial biodiversity District Council. from tidal inundation.

Environmental and social enhancements delivered by the preferred option 2.5.27 We will provide habitat enhancements during implementation. Pawlett Hams realignment will also provide significant biodiversity benefits once implemented Enhancement opportunities at project level would include creation of freshwater habitat in borrow pits, enhancement of the Parrett Trail with seats, planting and information boards. 2.5.28 Otherwise we are unable to safely contribute to our Region Recreational Strategy as the Parrett Estuary is a dangerous stretch of water and we should not encourage its recreational use. 2.6 Choice of Preferred Option Technical Assessment 2.6.1 All our shortlist “Do Something” options are technically viable and provide the indicative range of protection for at least half the Strategy period (i.e. between 1:100 and 1:300 in urban areas/high grade land and between 1:2.5 and 1:20 in the agricultural areas). 2.6.2 Options must be compatible between FMUs e.g. we cannot set back defences downstream of Bridgwater today as this would raise tidal water levels in Bridgwater (refer to 2.2.12g). However, we can set back defences downstream once Bridgwater defences are upgraded to account for sea level rise and the impact of setting back downstream. 2.6.3 Do nothing and do minimum options do not meet our objectives. These options also present a considerable risk to life through uncontrolled breaches. 2.6.4 Historically the rural defences upstream and downstream of Bridgwater have been kept at a lower standard than Bridgwater. Any overtopping outside of the town will provide some attenuation of flood levels in Bridgwater and therefore the logical choice of defence standards would be to maintain this differential to minimise damages in over-design events.

22 Environment Agency – SW Region PEFRMS June 2010

Economic Assessment and Decision Rule 2.6.5 Table 2.14 shows the overall environmental suitability, damages, benefit/cost ratio and incremental benefit/cost ratio of each option for each FMU. The preferred option is highlighted in bold in each case. 2.6.6 In Table 2.14 the incremental benefit-cost ratios are used to compare the alternative alignments of defence and the timing of intervention against the do minimum option rather than to assess the standard that the defence should provide. The design standard is identified in section 2.4.15 and in Table C10 in appendix C. 2.6.7 In accordance with the FCDPAG3 decision rule, our preferred option for the Cannington FMU throughout the strategy period is to hold the line using a series of 35 year upgrading programmes to keep pace with sea level rise (in line with the estimate serviceable life of the embankments from new and accepting a 5 to 10 year practical implementation programme within each 35year cycle). As this is only marginally preferred over a realignment option, this will need to be reviewed in future reassessments of the strategy. 2.6.8 In accordance with the FCDPAG3 decision rule, the preferred option for both Bridgwater East and West is to hold the line by upgrading as necessary until sea level rise is such that it becomes viable to provide Bridgwater with a tidal surge barrier. The current optimum time is between 2041 and 2050. However, a 10 year development period will be needed. 2.6.9 Five alternative barrier locations were considered during the assessment. This analysis showed that costs of the barrier were sensitive to the width of the river, because of the extensive foundations and cut-off walls required. Environmentally there are no strong drivers in relation to the ultimate location, so the minimum cost approach was adopted, locating the barrier immediately downstream of the urban area. Whilst locating the barrier further downstream would reduce the length of embankment to be raised in the future, the saving is insufficient to offset the increased barrier costs. Therefore we would only consider a downstream location if it brought development benefits and developer contributions were forthcoming.

23 Environment Agency – SW Region PEFRMS June 2010

Table 2.14 – Summary of Option Assessment Flood management unit Cannington Bridgwater East Huntspill & Pawlett Bridgwater West

Option £m £m £m £m B/C B/C B/C B/C B/C B/C B/C Env Env. Env. Env. Incremental Incremental Incremental PV PV Damages PV Damages PV Damages Do nothing
357 NA NA
1,699 NA NA
185 NA NA Do minimum
285 93.3 NA
916 1251.7 NA
135 51.9 NA Hold the line  15 11.8 9.6  - 70.1 39  2.5 5.5 4.1 Hold the line/Managed  16 11.8 9.5 NA NA NA NA NA NA NA NA Realignment – C1 Hold the line/Managed  15 11.7 9.5 NA NA NA NA NA NA NA NA Realignment – C2 Hold the line/Managed
/ 19 10.7 8.7 NA NA NA NA NA NA NA NA Realignment – C4 Hold the line/Managed NA NA NA NA NA NA NA NA  4.5 5.6 4.2 Realignment – H&P1 Barrier NA NA NA NA  - 57.4 32 NA NA NA NA Hold the NA NA NA NA  - 95.4 53 NA NA NA NA line/Barrier Flood warning (with other  - 79.0 -  - 876.7 -  - 44.2 - preferred option) Note:The residual SoP in any period has been used to assess the value of benefits (where initial SoPs deteriorate with time in response to sea level rise) to ensure a precautionary assessment. Similar figures have been used in Table C10 which uses the mean to present the most likely outcome.

2.6.10 Again in accordance with the FCDPAG3 decision rule, the preferred option for the Huntspill & Pawlett FMU is to hold the line until Bridgwater flood defence is improved (provisionally 2046) and then realign the defences at Pawlett Hams, cutting off this meander of the estuary. This will provide 387ha of BAP habitat, 241ha of which will contribute to the compensatory habitat need of the Severn Estuary and is the most economically viable option. 2.6.11 We also recommend that flood warning and awareness improvements are made in tandem with all the preferred options. No major new investment is required.

Economic and Environmental Sensitivity (including Climate Change) 2.6.12 This strategy is being launched at a time when there are uncertainties in the predictions which will influence the future of the Parrett Estuary, the major ones being the rate of sea level rise and potential energy generation schemes in the Severn Estuary. Therefore, this strategy does not only identify programmes of work, it also identifies when to review and ask questions. We have drawn up the strategy based on the knowledge of today, but we have also set the baseline to allow us to be flexible in the long term and respond to the reality of the emerging physical environment and national priorities which may affect our future decisions. To reflect this we will commit to review this strategy at least every 10 years, or review it to assess the potential impact of wider considerations (such as 24 Environment Agency – SW Region PEFRMS June 2010 commitment to a Severn Barrier option, or a change in driving policies such as the Habitat Regulations etc.) whichever is the sooner. 2.6.13 Contributions from developers could alter the timing and funding requirement of the proposed tidal barrier in particular.

Recommended Overall Preferred Option 2.6.14 The overall preferred option derivation is shown on Table 2.15 below:

Table 2.15 – Recommended overall preferred option and outcome measures FMU Preferred Option SoP in 2108 B/C PV PV No. Props ratio benefit cost protected £k £k 2108 Res (comm) Cannington Hold the line with 1 in 50 11.8 343,000 29,000 1670 (46) upgrading (overtopping) 1:200 (Breach) Bridgwater Hold the line with Higher than 1 in 95.4 1,700,000 17,800 1140 (116) West upgrading/Barrier 50 (overtopping) Bridgwater Hold the line with 1:200 (Breach) 7370 (696) West upgrading/Barrier Huntspill & Hold the line with 1 in 50 5.6 180,000 32,600 786 (85) Pawlett upgrading/Managed (overtopping) Realignment – H&P1 1:200 (Breach) 2.6.15 The preferred options selected for each FMU meet the technical criteria identified in Section 2.7.1. There are no political or social issues affecting the appraisal of options at present although policy drivers may change in the future. 2.6.16 This strategy will provide a minimum standard of protection (against overtopping) of 1 in 50 probability (2%AEP). There is justification for improving the tidal defences to Bridgwater to a higher standard and we expect this to be provided by a surge barrier rather than raising the defences. The defences would provide a good standard of protection to10,864 residential properties and 943 commercial properties through to 2108. 2.6.17 The strategy will avoid £2.26 billion of present value damages over the 100 year period. 2.6.18 Table 2.16 shows environmental impacts and opportunities associated with the preferred strategy.

Table 2.16 – Environmental impacts and opportunities Positive impacts of strategy • Higher level of flood protection to the surrounding residential properties, infrastructure, public amenity, designated sites and reduce risk of saline intrusion to groundwater. • Reduced flood risk and ease of access leads to reduced health and safety risk. • River Parrett Trail would be unaffected by realignment option and upgrading the banks will improve its protection and offer opportunities to enhance it. • Realignment will allow up to 387 ha of inter-tidal saltmarsh habitat to be created. • Populations of protected/RDB/BAP species may increase following habitat creation. • Reduced risk of contamination from agricultural, sewage works and consented discharge sources following construction of surge barrier. • Minor set back of existing line of defence allows the estuary to fall into a more natural form. • Navigation of the Parrett Estuary and operation of the wharfs would be maintained. • Improved flood protection to 6 Scheduled Monuments, 59 listed buildings and a number

25 Environment Agency – SW Region PEFRMS June 2010

Table 2.16 – Environmental impacts and opportunities Negative impacts following environmental mitigation • Productivity of up to 387 ha of agricultural land at Pawlett Hams would be reduced to create compensatory habitat. • Public Rights of Way at Pawlett Hams would be lost or more likely re-routed. • Regular inundation of up to 387 ha of the Severn Estuary SPA and Ramsar site to create BAP habitat, although this could be offset by creation of similar ditch networks at nearby sites. • Visual amenity of the landscape may change due to wider and taller banks. Potentially adverse impact of surge barrier on visual amenity. • Power lines within the realignment area would need to be protected from flooding. • Navigation would be restricted when the surge barrier is closed. • Loss of 6 statutory historic records following realignment, such as peats and trackways (refer to the accompanying Strategic Environmental Assessment for details). Potential for erosion of unknown sites

Outcome Measures 2.6.19 Outcome measures relate to capital expenditure works planned under the strategy by 2017 i.e. Cannington FMU outfall and embankment works and upgrading of short lengths of Bridgwater defences. All other works until that date will be to maintain the current defences, provide safe access or enhance flood warning measures. Table 2.17 – Outcome Measure 1 Economic Benefits to 2017 CSR

Pvb PVc Option £k £k PVb/PVc Ratio Hold the line – Cannington 248,000 21,000 11.8 Hold the line - Bridgwater East and West 332,000 3,480 95.4 Hold the line - Huntspill and Pawlett 0 0 0

Table 2.18 – Outcome Measure 2 Number of households moved out of any flood probability category to a lower one to 2017 CSR Option No moved to lower category Hold the line - Cannington 1,870 Hold the line - Bridgwater 756 East and West Hold the line - Huntspill and Pawlett 0

2.6.20 No properties are attributable to Outcome Measure 3 (Number of households for which the probability of flooding is reduced from significant or greater (high risk) through projects benefiting the most deprived 20% of areas to 2017 CSR). 2.6.21 0.3 ha of BAP habitat will be created due to upgrading of Cannington FMU defences (minor realignment on principally the existing line), which will contribute to Outcome Measure 5 (Contribution to the UK Biodiversity Action Plan habitats to 2017 CSR).

Table 2.19– Outcome Measure 5 Contribution to the UK Biodiversity Action Plan habitats to 2017 CSR Option Contribution ha Hold the line – Cannington 0.3 Hold the line - Bridgwater East and West 0 Hold the line - Huntspill and Pawlett 0

26 Environment Agency – SW Region PEFRMS June 2010

Table 2.20 – Final Outcome Measures to 2017 CSR Option Outcome Measure Score

Cannington Outfalls & Urgent Embankments 15.30 (Min)

Cannington Embankments 4.37 Bridgwater Embankments 32.80

Residual Risk 2.6.22 This is a low risk strategy that promotes proven solutions implemented over a long timescale. There is a low level of controversy attached to the solutions proposed. Notable risks are shown table 2.21 below.

Table 2.21 - Strategy main risks Risk Key Mitigation Certainty of sea level The options are unaffected by SLR. Revised predictions will only change the rise (SLR) timing of the requirements. Strategy reviews should focus on this estimate. High risk Low risk Global economic Would be likely to alter benefit cost ratios but ranking of options would remain climate influencing the same. costs Medium risk High risk Over design event Ensure major incident plan is in place. Continue flood warning practices. Low risk Low risk 1) Construction of barrier brought forward with external contributions to assist Political drivers development. Work closely with Sedgemoor District Council. change policy 2) Value of environmental replacement habitat reduced in favour of preserving Medium risk farmland. Review policy and update strategy as required. Low risk (as there is time for strategy to adapt) Only one option i.e. Bridgwater Bay lagoon, has a potential hydraulic impact, Severn Estuary tidal whilst others have habitat needs. We will check invest programme at regular power solutions strategy reviews. Medium risk Low risk 2.7 Other Considerations

Health and Safety 2.7.1 Public safety - This strategy uses well tried techniques and experience to prevent people from being exposed to risk and has been reviewed by a CDM coordinator. This is in line with the Environment Agency’s Public Safety Risk Assessment (PSRA) Policy and PAG4. However, we have developed options with an awareness of PSRA, particularly with regard to the risk of uncontrolled breach and degradation of the embankments, many of which serve as public footpaths. Specific risk assessments will be needed at project stage. 2.7.2 Construction and Safety – At this stage the options are not sufficiently developed to allow a comprehensive assessment, but points to further consider at project stage include: a) dangers associated with the deep soft muds on the estuary side of the defences; b) fast flowing tides; c) high steep banks; d) livestock in rural areas; e) temporary reduction in standard of defence should be avoided as this will increase the risk of rapid inundation of a wide area; and f) dangers associated with working on restricted sites near traffic will relate to works in urban areas.

2.7.3 Emergency planning – This is a vital part of managing the risks of tidal flooding and the authorities constantly update their procedures to account for changing circumstances. It is important that the outcomes of this strategy and assessment of flood risk areas are fed into the emergency planning system. This is especially important as there are several 27 Environment Agency – SW Region PEFRMS June 2010 emergency service sites with in the flood risk zone (refer to Figure 2.5 in Appendix A). Local councils are already aware of this strategy through the consultation progress and partnership with Sedgemoor District Council on its Local Development Framework.

Sustainability 2.7.4 Options have been assessed to ensure delivery of sustainable construction targets. An important criterion of option development has been to develop integrated engineering, environmental and sustainable solutions. We will develop this further at project stages. 2.7.5 A carbon calculator has been used to identify relative carbon footprint for all options considered as potentially viable. Details of the results are included as Appendix J. In rural FMUs holding the line or realignment to H&P1, C1 and C2 with holding the line elsewhere have the least and comparable carbon impacts. In Bridgwater barrier options have the least carbon impact.

Planning Policy and Development Control 2.7.6 We will feed the revised flood risk assessment for Bridgwater, in particular where significant amounts of development are planned, into planning policy through our development control facility and will be administered in accordance with PPS25. Major developments in Bridgwater will contribute to costs of a tidal surge barrier and we are working with Sedgemoor District Council to ensure this is clearly represented in the Local Development Framework. 2.7.7 Managed retreat at Pawlett Hams will not be a significant planning and development control issue as no properties are affected and this area is not designated for development.

Flood Warning 2.7.8 Flood warning and awareness is a generic option that will enhance other options reflecting revised flood risk assessments made by this strategy alongside any construction solutions implemented. Our present system uses established tide gauges at Hinkley Point and Bridgwater to supplement warnings from the Storm Tide Forecasting Service. We will invest in flood warning under national and regional investment programmes to improve software applications or communication networks. This investment will be targeted, to be more specific and relevant based on the flood risk mapping generated during this strategy. Its relevance will ensure that the public will heed the warning more effectively. It is generally not possible to warn effectively against breach failure to reduce damage to property, because of the rapid onset of flooding. 2.7.9 Under the “do nothing” option risk to life is significant and has been included as a economic parameter in our benefit calculations. Under “do something” options our actions substantially reduce the risk to life. Therefore, the impact of flood warning on further reducing risk to life and flood damage to property is negligible. On this basis flood warning benefits have not influenced the economic assessment. 2.7.10 Flood Warning is cost effective as it is relatively inexpensive and is justified by the economic return that would occur in an over-design event. It is not an effective option on its own as it does not manage the impact of the “do nothing” scenario where property is written off within the strategy period and Bridgwater becomes unviable as a a town. Maintenance 2.7.11 We have assessed maintenance requirements and costs for the preferred strategic options and we have included allowances in the benefits cost assessment.

Monitoring 2.7.12 We will arrange monitoring to provide information needed for detailed design and to support decisions about tidal defences in Bridgwater in particular. It will be targeted at

28 Environment Agency – SW Region PEFRMS June 2010 providing information regarding the changing environment and its sensitivities, climatic factors and the dynamic form of the estuary and its sediments.

Reviews 2.7.13 This strategic report will be reviewed in the future to take account of changes in flood risk, national policy, funding and environmental issues. We will review strategy proposals at least every 10 years against the new data sets arising from the monitoring programme e.g. condition assessments, aerial photos for erosion/deposition, bank levels and sea level rise, or sooner if fundamental influences change (e.g. commitment to a Severn Estuary Barrier option, change in Habitat’s regulations, guidance on sea level rise predictions etc.). Data from the SW Coastal Observatory will be particularly important, refer to www.channelcoast.org/southwest for details. 2.7.14 In approximately 2020 we will need to decide whether a surge barrier to defend Bridgwater in the long-term and if managed realignment (including possibility of regulated tidal exchange) at Pawlett Hams remain the preferred options. Factors which will influence the decision and alter the balance of the preferred option will be actual climatic factors, environmental and land use policy at that time and improved estuary data derived from the monitoring programme (including environmental).

Technical aspects of design 2.7.15 Hydraulic analysis . We have used a proven ISIS hydrodynamic 1-D model, which runs from the estuary mouth to above the tidal limit of the estuary, to determine water levels for a range of flood risk probabilities. We have run the model assuming spills and also with ‘glass walls’. We have used the model to test the effects of allowing some overtopping of rural defences. 2.7.16 Tide levels. We have used tidal levels at the downstream boundary taken from the Severn Estuary/ Bristol Channel model developed within the Severn Estuary Flood Risk Management Strategy. 2.7.17 Fragility analysis. We have used a fragility analysis developed for this strategy, which incorporates our deterioration rates for defences being used at national level to draw up system asset management plans. This also incorporates deterioration which will be caused in some places as a result of the tendency of the estuary to try to increase in width in response to an increased tidal prism, an effect of sea level rise. The risk of breaching failure of embankments is a very important element in the analyses used. Overtopping which has a low risk of breaching embankments can be tolerated in rural areas. We have used standard guidelines, including those within the Eurotop manual to determine tolerable overtopping rates, which are dependent on embankment condition. 2.7.18 Digital ground models. We have made extensive use of ArcGIS software to use digital ground models based on LiDAR surveys. In particular we have used this tool to determine the spread of floodwater in flood cells to differentiate between the probability of overtopping a defence and the probability of receptor properties being damaged as a result. 2.7.19 Surface water. Discharge will be maintained not enhanced. During states of surge tide surface water discharge in Bridgwater will be improved by the surge barrier i.e. surface water flood risk is improved. Strategy impacts will not be felt for 30 years, therefore discussion with water utilities should be made near time of implementation.

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3 STRATEGY PLAN

Achievement of strategy objectives 3.1 Table 3.1 shows how our preferred option meets our strategy objectives and relates them to our National themes.

Management approach 3.2 Refer to summary figures 3.1 and 3.2.

Capital works to 2017 CSR period 3.3 The preferred plan is to maintain and hold the line in all FMUs in the short term. To do this we will carry out general maintenance and: a) Present to 2011 i. Upgrade four failing Cannington outfalls (currently progressing under framework for action) ii. Carry out urgent bank raising work on lengths of Cannington FMU embankment currently at immediate risk of failure (refer to figure 3.3 vulnerability assessment). Appraisal is due to be complete 2010 b) 2011 to 2014 i. Upgrade all Cannington embankments with a standard of protection of less than 1:50 to a residual minimum standard of protection of 1:50 by 2046. c) 2014 to 2017 i. Upgrade short lengths of wall in Bridgwater currently with a low standard of protection to 1 in 200 (0.5%AEP). Note though that few properties are at risk as overtopping volumes are small.

3.4 Note. Huntspill and Pawlett defences have a standard of protection lower than 1:50 (2% AEP) but the outcome measure score is not sufficient to consider improving these defences until after 2017.

Capital works medium term (9 to 20 years) 3.5 During this period we propose to continue our short-term programme of works to hold the line in all FMUs and upgrade vulnerable defences and those failing to meet a residual minimum 1:50 standard of protection in rural areas and a 1 in 200 standard of protection in Bridgwater will be maintained. These works will be sequenced as the need arises as indicated on Figure 3.3.

Capital works long term (21 to 100 years) 3.6 By year 2046, we will construct a surge barrier, which will only operate to exclude the highest tide levels. Defence levels could then be maintained at their current level or reduced in level providing closure of the barrier can be guaranteed when it is needed. Lead in time for this work will be of the order of 10 years and will require further studies prior to that date. 3.7 Until 2046 (within 2030 to 2050) we will hold the line and upgrade as indicated on Figure 3.3. 3.8 After 2046 enhanced protection of Bridgwater will allow us to implement the managed realignment of the Pawlett Hams defence. Elsewhere we propose to continue to upgrade the existing defences and hold the line throughout the strategy period. However, this decision is finely balanced with managed retreat options in Cannington FMU and we will keep this under constant review if any of our baseline assumptions change significantly. If this were to happen we would create Atlantic meadow saltmarsh where there is currently medium grade farmland.

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Table 3.1 Comparison against strategy objectives Objective (shortened version) Short Long term term Realignment Hold the H&P1/Surge line Barrier/Hold the line Reduced flood Integrated approach for the whole estuary   risk Reduce flood risk via flood warnings and sustainable   defences Provide flood management solutions that: are appropriate   technically economically, environmentally, socially and are adaptive to climate change Maintain the discharge of surface water * * An enhanced Integrated approach for the whole estuary   environment Manage risks of saline intrusion to wildlife and farming   for wildlife interests.

Provide flood management solutions that: are appropriate   technically economically, environmentally, socially and are adaptive to climate change Improved and Provide flood management solutions that: are appropriate   protected technically economically, environmentally, socially and are inland and adaptive to climate change coastal waters Restored, Provide flood management solutions that: are appropriate   protected land technically economically, environmentally, socially and are with healthier adaptive to climate change soils Maintain the discharge of surface water * *

Manage risks of saline intrusion to wildlife and farming   interests. Wiser, Reduce flood risk via flood warnings and sustainable   sustainable defences use of natural resources Limiting and Reduce flood risk via flood warnings and sustainable   adapting to defences climate change Provide flood management solutions that: are appropriate   technically economically, environmentally, socially and are adaptive to climate change A better quality Integrated approach for the whole estuary   of life Reduce flood risk via flood warnings and sustainable   defences Provide flood management solutions that: are appropriate   technically economically, environmentally, socially and are adaptive to climate change

Other action throughout strategy period (0 to 100 years) 3.9 We will continue to maintain the defences to ensure that the defence standards are retained. Where realignment is proposed we will maintain the existing defences and not allow them to fall into a poor condition until realignment has taken place. 3.10 Flood warning and awareness activities will be retained and targeted to reflect our improved knowledge of the flood risk areas. 3.11 We will regularly revisit this strategy at 5 to 10 year intervals, or sooner if crucial data sets are significantly altered (e.g. sea level rise guidance, environmental prioritisation, construction costs). 3.12 Our development control staff will advise on flood risk for new developments based on the findings of this strategy and any subsequent updates of this document. 3.13 To enable future works to be effective and appropriate we will continue to monitor the changing shape of the estuary using LiDAR and bathymetry. We will also commence collecting sediment data to inform the barrier development in particular.

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Management of environmental impacts 3.14 We have assessed the impacts on environmental interests. Negative impacts on internationally designated areas have been considered in the Statement of Case accompanying this document which shows an over-riding public interest. We will compensate for lost BAP habitat with the realignment of defences at Pawlett Hams. We will mitigate for lost national interest freshwater habitat as we carry out our implementation programme. We will ensure archaeological interests are met with appropriate action throughout implementation of the strategy. 3.15 We will seek to avoid or lessen the any significant adverse effects of the strategy at the earliest opportunity, either through our own actions or through liaison with the statutory bodies, groups or individuals who are responsible for the maintenance of associated assets that do not fall under our remit. We will carry out environmental monitoring of potential realignment areas (refer to Table 7.1 of the SEA). This will include the Cannington area which although not currently preferred may become so if the balance of factors change. We will also carry out sediment dynamic modelling of the estuary in preparation for the tidal surge barrier.

Programming of works arising 3.16 The general programme of the overall strategic proposal is shown on Figure 3.1 included in Appendix A and described with the proposed works in section 3.2 above. 3.17 The programme for the short term work to be implemented before 2017 is as shown in the following tables.

Table 3.2 - Cannington outfalls programme of work Phase Timescale Submission of PID June 2009 Complete detailed design Dec 2009 Construction start March 2010 Construction substantially complete July 2010

Table 3.3 - Cannington embankments programme of work Phase Timescale Submission of PAR for urgent work (2011) October 2009 Complete detailed design April 2010 Construction start July 2010 Construction substantially complete October 2010 Submission of PAR for upgrading work (2014) April 2012 Complete detailed design October 2012 Construction start April 2013 Construction substantially complete October 2013

Table 3.4 – Bridgwater programme of work Phase Timescale Submission of PAR for Bridgwater upgrading (2017) April 2015 Complete detailed design October 2015 Construction start April 2016 Construction substantially complete October 2016

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Procurement/Project Management 3.18 Work programmed to 2017 comprises embankments, outfalls and excavations for freshwater habitats. Existing framework contracts are suitable to implement these works. We will package works into large value contracts, probably with one NCF supplier, so efficiencies can be gained over a period of years through re-use of material, access tracks etc. 3.19 Extensive clay deposits exist in the flood plain so we anticipate most bank construction will be conventional. But we shall investigate innovative techniques such as using old tyres for fill at detailed design stage. Key staff responsible for preparing this strategy are summarised in below: Agency Staff Framework Staff Client NEECA Team Project Sponsor – Nick Lyness Project Manager – A Purcell Business User – John Viney SEA – U Bycroft/P Whittock Strategic & Dev. Planning Team Leader – Economic Lead – J Mason Alan Rafelt ncpms Project Executive – John Taberham Project Manager – G Quarrier NEAS NEAS Officer – C Wilson Technical Advisers Procurement – Scott Lawrance Estates Officer – Kevin Aylott Benchmarking 3.20 We have benchmarked this strategy against the other local Parrett banks works and wider Somerset embankment works. Welmore sluice in Anglian Region is similar in size and operation and has been used for details of the barrier. 3.21 Other coastal flood risk management strategies also prepared by Black & Veatch include: Humber, Blyth, Ouse to Seaford, Tidal Tees and Deben. (suffolkestuaries.co.uk) 3.22 Contractors have not been directly involved with preparing this strategy. However, data from contractors carrying out recent work has been used.

Spend Profile 3.23 The spend profile is as shown on table 3.6 below.

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Table 3.5 – Spend profile Maintenance Cost Year Capital Cost (£k) Total Cost (£k) (£k) 2008/9 - 79 79 2009/10 755 79 834 2010/11 2200 79 2280 2011/12 5130 79 5210 2012/13 5130 79 5210 2013/14 5140 79 5220 2014 - 2017 3000 316 3320

2017– 2046 33700 2210 35940

2046 - 2081 74200 8440 82600

2081 - 2108 52400 6750 59200

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