West of England
Full Business Case Template Scheme: ASEA Ecology Mitigation and Flood Defence
Originated Reviewed Authorised Date 1 Version 1.0 GW BS 11/01/2018 2 3
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Doc v21 Last updated Nov 2017 Executive Summary
The project comprises delivery of significant flood defence and ecological assets designed to unlock and safeguard development at Avonmouth‐Severnside Enterprise Area (ASEA), located between the Bristol Channel and the City of Bristol and spanning South Gloucestershire (SGC) and Bristol City Council (BCC). The flood defence element of the project will primarily enhance and upgrade existing flood defence infrastructure along a 17km stretch. The infrastructure will provide flood risk management to a 1 in 200‐year (0.5% Annual Exceedance Probability [AEP]) Standard of Protection (SOP), based on hybrid 2076 and 2098 design levels (i.e. taking into account climate change, coastal change and sea level rise). The 2098 design level will be provided south of Binn Wall to maximise protection of existing and future development in ASEA. The 2076 design level will be delivered north of Binn Wall, where flood risk to ASEA is lower. The ecological mitigation element of the project comprises the provision of at least 85 ha of wetland habitat creation, in line with the recommendations of the Cresswell Study1.
The project rationale is underpinned by local and sub‐regional economic development and planning aspirations to unlock the full economic potential of ASEA. Flood defence investment is required to ensure that future development at ASEA benefits from the Environment Agency’s (EA) recommended SoP for new developments, i.e. 1 in 200 years (0.5% AEP). The ecological mitigation is required to ensure that the statutory environmental impacts of ASEA development are managed to satisfy the requirements of the Cresswell Study. By satisfying the EA and Cresswell Study regulations, full development at ASEA is more likely to be acceptable in planning terms thus bringing forward desirable economic growth for the region.
The rationale for public sector investment in the project is predicated on the presence of market failure at ASEA as well as the proposed flood defence infrastructure and ecological assets acting in the general public interest. From a market failure perspective, the presence of the 1957/58 planning consent creates imperfect competition conditions at ASEA. The planning consent allows development in the 1957/58 planning envelope to proceed based on legacy planning consents, without requirement for appropriate investment in strategic flood or ecological mitigation. As such, the financial burden of delivering these assets would be passed onto development plots lying outside the 1957/58 planning envelope or public authorities holding statutory responsibility for the measures, impacting on the financial viability of such sites and therefore the ability to bring forward the development. These conditions confer competitive advantage on sites within the 1957/58 envelope. Development viability is also a concern in the absence of strategic flood defence infrastructure, as localised land raising (which has been pursued at some development sites to date), would become increasingly expensive over time as higher levels of land raising are required to mitigate against climate change effects. This will erode development viability by increasing land raising costs and reducing the scale of development area. From a public good perspective, the flood defence element of the scheme will also help to safeguard existing economic activity already located in ASEA as well as safeguarding properties from flood events.
1 Identified by the Severnside and Avonmouth Wetland Habitat Project (Stage 1 & 2) and referred to as the Cresswell Study
Doc v21 Last updated Nov 2017 The economic appraisal demonstrates that the project will represent excellent value for money.
In terms of commercial and management considerations, SGC and BCC will act as promoters for the project. EA will act as delivery partners, with responsibility for procurement via existing mechanisms such as WEM Framework (Lot 4: Asset Delivery). The LEP will act as key funding partners. Within this context, SGC, BCC, EA and the Local Enterprise Partnership will all have representation on the governance structures that will oversee project development and implementation. These include the Strategic Directors Board (SDB), who will provide overarching authority for the ASEA programme and the Delivery Board who will help realise the agreed outcomes and benefits for the ASEA development area. Both governance structures are committed to unlocking the significant full economic potential of ASEA through implementation of the flood defence and ecological mitigation assets that form this project.
Doc v21 Last updated Nov 2017 1 Strategic Case
1.1 State Aid Considerations The Department for Business Energy and Industrial Strategy (BEIS) suggest that State Aid can be given to support a wide variety of activities including environmental protection and where intervention is needed to deliver growth and other important objectives. By providing flood protection (alongside ecological mitigation) to unlock economic growth and development, the main objectives of the project are closely aligned to the types of activities that can benefit from State Aid. Further, paragraph 203 of the Official Journal of the European Union (OJEU) C262/44 states that infrastructure for activities that the state normally performs in the exercise of its public powers (e.g. flood protection) fall outside of the scope of State Aid rules. The Department for Business Innovation and Skills (the predecessor to BEIS) established the following series of questions, to help determine whether funding would represent a violation of State Aid rules: 1. Is the assistance granted by the state or through state resources? Funding is provided via state resources, routed via public sector bodies such as the Environment Agency (EA) and voluntary organisations between business and local authorities such as the LEP. 2. Does the assistance give an advantage to one or more undertakings over others? The proposed assets represent appropriate public infrastructure, acting as a public good and benefiting all existing and potential future residential and commercial properties in the area. The project will not benefit one developer or landowner exclusively, it will be of further benefit to the public in general and the wider economy across the West of England. 3. Does the assistance distort or have the potential to distort competition? The project will deliver assets where there is no direct competition to provide similar infrastructure, therefore competition will not be distorted. Replication of the infrastructure would be uneconomical, meaning that the proposed assets represent a natural monopoly. Further, the infrastructure acts as a public good, providing benefits to society at large. 4. Does the assistance affect trade between Member States? Occupants of the existing and proposed residential and commercial properties at Avonmouth Severnside Enterprise Area (ASEA) could feasibly originate or be based in any member state. Given the responses to these questions, public sector funding for the project is considered to comply with State Aid regulations. 1.2 Project Description The project seeks to deliver a strategic flood defence solution and associated ecological mitigation to unlock and safeguard development of the ASEA. The flood defence element of the project seeks to provide a 1 in 200‐year (0.5% AEP) standard of protection (SoP) to a hybrid 2076/2098 design level. This will reduce flood risk from tidal flooding to the ASEA development area in Bristol and South Gloucestershire. The project is located between Bristol and the Severn Estuary, immediately adjacent to the M4, M5 and M49 motorways as demonstrated in Figure 1. It includes upgrading of key tidal defences on the Severn Estuary and associated works to discharge fluvial flows to the Estuary. The project area, including ASEA, is almost entirely within a single tidal flood cell, protected by around 17 km of defences or raised railway embankment, including sea walls, revetments, embankments and tidal outfalls. Existing defences are generally in good condition, though at some locations they require refurbishment and there are low spots. Furthermore, there are longer term implications of coastal change, climate change and the consequential sea level rise predicted. The scope of upgrading is principally determined by the requirements of new areas of employment‐led development. This brings
Doc v21 Last updated Nov 2017 additional opportunity for cost‐effective improvements in flood risk for existing properties across the existing flood plain. The ecological mitigation element of the project involves wetland habitat creation. Wetland habitat creation is included within the project to ensure that supporting habitats to the Natura 2000 Severn Estuary site are maintained after the industrial development takes place. The requirement for wetland habitat creation is not directly contingent on upgrading of flood defences; rather it is required to compensate for the existing development at ASEA as well as unlocked development at the site. Compensation for coastal squeeze on the tidal defences has been provided through completed projects in Somerset and the Forest of Dean. Further, a Habitat Regulations Assessment is currently in progress to identify any additional ecological mitigation required to offset construction stage impacts. The project comprises work in five defined areas, three areas of flood defence works and two areas of ecological mitigation in the form of wetland habitat creation, as shown in Figure 1.1.: Area 1: Severnside – Old Passage to Binn Wall, representing the northern section of flood defence works. Area 2: Avonmouth Docks – Bristol Port to the River Avon, up to the proposed Portway P&R site. Representing the southern and riverine sections of flood defence works. Area 3: Chittening Warth – Station Road to Chittening Warth Industrial Estate, alongside the route of the Severn Beach Railway Line and representing the central section of flood defence works. Area 4: Hallen Marsh – 100 ha of agricultural land north east of Avonmouth Docks, bounded to the east by M49 and south by a railway line. Area 5: Northwick – 85 ha of agricultural land to the West of Area 1, bounded to the north by M48 and south by M4.
Doc v21 Last updated Nov 2017
Figure 1.1. Project Overview 1.3 Project Objectives and Case for Change The primary project objectives are listed in Table 1.1.
Table 1.1. Overall Strategic Objectives Source: CH2M Objective Theme Objective Description Unlocking Ensure the flood defences and ecological mitigation in ASEA are adequate for economic the lifetime of the proposed industrial development, to support business development growth.
Providing Ensure the environmental impacts that result from the proposed industrial ecological development will be mitigated such that the development plans will be legally mitigation compliant.
Doc v21 Last updated Nov 2017 Adhering to Discharge requirements identified within the ‘review of consent’ of Severnside statutory planning planning permission under Regulation 63 of the Habitat Regulations 2010. and other regulations Safeguarding Ensure the flood defence improvements required for new development are of existing economic benefit to the existing properties and the area as a whole. activity and settlements
The case for change can be understood in terms of the key issues affecting the ASEA development area, which the project should seek to leverage from or address:
Strong economic and market demand drivers for employment‐led development in the West of England; Supply‐side constraints around supply of suitable industrial/warehousing premises; ASEA’s significance and role as a key current and future employment destination in the sub‐ region, which heightens the importance of realising the full economic potential of the area to support the region’s growth aspirations; ASEA’s role in contributing to the Growth Incentive element of the City Deal. The Growth Incentive means that development at key enterprise zones and areas in the West of England should be promoted to facilitate business rate growth, which can be recycled into wider infrastructure investment and economic development throughout the West of England via the Economic Development Fund; Development at ASEA is laden with a significant infrastructure burden that the private sector may struggle to meet alone. Coordinated delivery of infrastructure is essential to ensure that ASEA can maximise its development and economic potential. Failure to do so could result in restricted development, leading to loss of additional economic output. Equally, there is a danger that the City Deal’s business rate forecasts are not met, jeopardising economic development across the West of England; The need to provide strategic ecological mitigation (as identified by the Severnside and Avonmouth Wetland Habitat Project [Stage 1 and 2], hereafter referred to as the Cresswell Study) in order for planning consent to be granted at many future developments within ASEA. In the event that the project does not materialise, further development of ASEA is likely to be limited, delayed or stalled indefinitely, meaning the full economic potential of the area would not be realised. Existing economic activity would be subject to increasing flood risk too thus potentially reducing the attractiveness to employment below current levels.
1.4 Rationale for Public Intervention At a strategic level, public investment is required to address flood risk issues and to deliver ecological mitigation to compensate for the environmental impacts of employment‐led development. Existing flood defences in the area provide a variety of standards of protection ranging from 1 in 10 years to 1 in 200 years. The EA’s recommended standard of protection for new development to be safe from tidal flooding is 1 in 200 years plus. Therefore, the existing flood defences do not provide the recommended level of protection for the proposed industrial and warehousing development at ASEA.
Doc v21 Last updated Nov 2017 Drawing upon findings of the Cresswell Study, there is a requirement for ecological mitigation to address the environmental impacts of economic development. Specifically, future development outside of the 1957/58 extant planning consent area at ASEA would be constrained without provision of new wetland habitat to satisfy the requirements of the Cresswell Study. Effectively, any proposed development plots promoted outside the 1957/58 area would be expected to provide extensive and prohibitively expensive ecological mitigation in order to maintain legal and planning compliance.
Further to the strategic rationale outlined above, public sector investment can also be justified on the basis of market failure. Market failure in the context of ASEA is two‐fold:
Development viability considerations affecting all of ASEA’s future development land, but plots outside of the consented 1957/58 envelope in particular. Imperfect competition allowing the 57/58 extant planning permission areas to avoid any statutory infrastructure cost burden relating to ecological mitigation or strategic flood defence. Market failures such as these act to delay or indefinitely stall development. Public sector delivery of a strategic flood defence solution and associated ecological mitigation works would address these market failures.
It would reduce the infrastructure burden on developers, and public authorities, reducing development viability concerns (particularly for plots outside the consented 1957/58 envelope). For example, in the absence of public sector funding, the project costs could be passed onto development outside the 1957/58 envelope. Such development represents around 75 ha of developable area
Simultaneously, land raising would also act to reduce the net lettable area for commercial premises as plot areas decrease to allow for embankments and landscaping associated with land raising. The reduction of net lettable area would be in the region of 40,000 sq m across ASEA, This would further erode development viability. Public sector investment in the project removes these development viability issues.
Public sector support would also remove the market imperfection that proffers competitive advantage to development within the 57/58 envelope to the detriment of non‐57/58 plots. It would also make recent and future development acceptable in planning terms. In light of the onerous high‐level cost estimates for delivering such flood defence and ecological assets, the private sector is unable to address these market failures. Hence, public sector support is required and appropriate to remove these specific barriers to development.
The project also warrants public support because it will provide public good assets. This is because the flood defence and ecological infrastructure represent assets that the market will have difficulty supplying without public sector intervention. Further, the assets will help to safeguard significant existing economic activity already present in ASEA (and further afield). Major employment sites
Doc v21 Last updated Nov 2017 including Avonmouth Docks, Central Park (occupiers include Tesco, Next and Royal Mail) and Access 18 (occupiers include Antalis, Nisbet, Budget Greetings Cards; Richard Austin Alloys, Flexipads World Class Ltd and New Earth Solutions) are already operational in the ASEA area and support a large number of jobs and economic output.
1.5 Strategic Fit The strategy is closely aligned to a range of national, sub‐regional and local economic and planning policy. At a national level, the project fits well with the National Planning Policy Framework which seeks to promote sustainable economic growth and reduce environmental threats posed by issues such as coastal flooding and climate change. At a sub‐regional level, ASEA is highlighted as one of the LEP’s most important economic development opportunities within the Strategic Economic Plan. However, flood risk is acknowledged as a key constraint to development, alongside the presence of internationally important habitat. Development at ASEA is also considered as a strategic priority in the draft West of England Joint Spatial Plan and the existing and emerging Local Plan’s for South Gloucestershire Council (SGC) and Bristol City Council (BCC). The suite of local planning policy documents also recognises the significant environmental, flood risk and infrastructure constraints that could hinder development at ASEA.
The project follows on from a large body of earlier work related to unlocking development at ASEA. This includes the Integrated Development, Infrastructure and Flood Risk Management Study2 which sets out potential mechanisms to address the identified constraints at the site and the Outline Development Strategy3 which establishes the significant economic potential of unlocking development at ASEA.
The project and its resulting economic impacts (i.e. the unlocking of the full economic potential of ASEA), are also a critical element of the Growth Incentive element of the City Region Deal. As a result, there is a significant financial incentive to promote development at ASEA by removing constraints associated with flood risk and ecological/environmental issues. This will allow the West of England to capture business rate growth to cover the capital cost of the implementing the project and support its wider economic development aspirations.
1.6 Options Appraisal The preferred intervention option for the flood defence element of the project was identified through the Avonmouth‐Severnside Flood Management Optioneering Technical Report4 which recommended improvement to existing tidal defences. The report estimated a cost of between £31m and £70m for delivery and identified a strong economic and funding case to pursue the design and delivery of a strategic flood defence solution.
Subsequently, the Severn Estuary FRM Strategy considered a large number of options. The recommended option was hold the line with upgrading to mitigate for sea level rise. For most locations, the preferred alignment of flood defences follows the line of existing defences, except for the Severn Beach railway section. Here, a new defence line set back from the railway on the landward side is currently proposed to avoid building within the environmentally sensitive RAMSAR site on the seaward side and affecting the railway embankment. Defences will primarily consist of earth
2 White Young Green (February 2012) 3 Amion Consulting/White Young Green (April 2012) 4 Atkins (November 2013)
Doc v21 Last updated Nov 2017 embankments with some flood walls proposed in specific locations where available land is constrained.
At a strategic level, the short list of options considered for the project are shown in Tables 1.2 and 1.3. For the EA, the minimum requirement to remove planning conditions on development is to provide 1 in 200‐year (0.5% AEP) SoP for 60 years, up to 2076 (i.e Option 4A). Options appraisal considers also the case for extending the 1 in 200‐year (0.5% AEP) SoP for 100 years (up to 2116) by either building higher defences as part of the project (Option 4C) or in future, in response to sea level rise (Option 4B).
Benefits delivered Reason for short- Option Description Target SoP / list Issues involved 1 Do Nothing No target. SoP Flood risk increases Baseline for quickly fails – quickly as defences economics regular breaches deteriorate, breaches are not repaired, and sea levels rise. 2 Do Minimum Current 5% SoP, Continued mitigation Baseline for EA’s (Environment falling over time due against present risk. Partnership Agency and private to sea level rise – Current annual O&M Funding Calculator owners maintain currently 1,050 cost ~£160k. Flood as part of FDGiA defences) homes at significant risk increases as business cases and moderate risk defences deteriorate (none at very and sea level rise. significant); within Development 100 years 1,195 continues to be homes at very permitted using significant risk. ground raising, using up storage for others. 3 Improved Tidal 0.5% SoP over 100 Reduced flood risk Phased delivery Defences: deliver years (to 2116) to Avonmouth- approach primarily FRM strategic policy Severnside area; to suit EA for phased mitigates for sea requirements, implementation; level rise. rather than wider primarily FDGiA and LEP economic PF funded; development Environment Agency . objectives working alone. Potential for 4 Improved Tidal Option 4A: 0.5% significant impacts Immediate delivery Defences: aimed at SoP to end of 60- including designated approach to suite economic year planning period sites, landscape and wider LEP development; short (falling to 2% SoP public. economic term by 2116) development implementation; Option 4B: 0.5% objectives. primarily ASEA LEP SoP to end of 60- and FDGiA funded. year planning period then upgrade to extend 0.5% SoP to 2116 Option 4C: 0.5% SoP over 100 years (to 2116)
Doc v21 Last updated Nov 2017 Table 1.3. Shortlist of Strategic options Source: Severn Estuary FRM Strategy, FDGiA OBC
Option Assessment process – options to improve tidal defences Do Nothing Baseline option against which all other options are measured. The Do (Option 1) Nothing option is used as a baseline economic reference case; this being the walk away option under which all operation and maintenance activities would cease. Under this option, once any part of the defence fails or breaches it would be left in that state indefinitely, quickly leading to an unacceptably high and progressively increasing level of flood risk. Do Minimum, Continued current activities for existing assets by the Environment Agency reactive and private owners. This option includes essential refurbishment and like- maintenance for-like replacement of assets, including the tidal defences and outfalls, (Option 2) and also to the assets on the fluvial (rhyne) system that drains floodwater from behind the tidal defences into the estuary. This option increases flood risk as problems would not be addressed in advance, leading to unacceptably high and progressively increasing level of flood risk. Improve Tidal The extent and scale of the flood defence works depends on the height of Defences existing defences and ground levels along the length of the scheme (Aust (Options 3, 4) to Avonmouth) and the target SoP – this differs depending on the option (3, 4A, 4B and 4C). Some sections of existing defences do not require raising in the short term – this applies to Binn Wall and Avonmouth Dock. Other sections of low lying land require defence works to be undertaken sooner – this applies to Aust and New Passage.
Options 1 and 2 were rejected as they did not contribute to the realisation of SGC, BCC and the LEP’s wider economic development objectives. Option 3 was also rejected on the basis that a phased approach to delivery over a number of years would not align with SGC, BCC and the LEP’s goal to promote economic development at ASEA now.
The preferred option selected was a hybrid version of Option 4A, which provides a 1 in 200 (0.5% AEP) SoP based on a combination of 2076/2098 design levels. The 2098 design level will be provided south of Binn Wall (i.e. Areas 2 and 3 in Figure 1.1) to maximise protection of existing and future development in ASEA. The 2076 design level will be delivered north of Binn Wall (i.e. Area 1 in Figure 1.1), where flood risk to ASEA is lower. This option is preferred on the basis that it is the most appropriate and acceptable design level from a planning perspective, providing sixty years of protection to ASEA from the conclusion of the City Deal period (2038).
Also note that the Strategic Director’s Board confirmed in Summer 2017 that options promoting 2076 design levels (i.e. Option 4a) were preferred over options promoting 2116 design levels (i.e. Option 4b and 4c). This view was informed by the analysis undertaken by CH2M that the costs of delivering 2116 design levels would be significantly higher than 2076. At the same time, the increase in benefits would be negligible as 2076 design levels unlock/safeguard development across the whole of ASEA; no additional development at ASEA is unlocked by 2116 design levels. As a result, whilst costs increase significantly, benefits increase only marginally for the 2116 design levels (Options 4b and 4c), which would reduce benefit/cost ratios. The decision to select a 2076/2098 hybrid option (Option 4a) merely reflects the opportunity to maximise protection of existing, recent and future development in ASEA south of Binn Wall. The supporting analysis justifying this position is provided in Appendices A and B.
The specification of the resulting flood defence works required to support Option 4a are outlined in
Doc v21 Last updated Nov 2017 Table 1.4.
Table 1.4. Preferred option – flood defence works required Source: FDGiA OBC
Scale of Defence to Flood Location Flood defence type achieve 0.5% SoP defences to 2076/2098 Avonmouth Park and Ride New sheet pile flood wall 0.8m high docks site adjacent to railway line (7km River Avon New RC flood wall to replace 1.2m high defence) existing bank Avonmouth New RC flood wall to replace 2.2m high docks tidal bank along dock edge North of Replace existing defences 1.7-2.7m high Avonmouth with RC wall docks Severnside Chittening Raise tidal flood bank Raise by 1.6m railway to Industrial Estate Severn Severn Beach New sheet pile flood wall on 1.1m high Beach railway line landward side South of Severn Raise existing tidal bank; Raise by 1.2m Beach carries Severn Way path South of Station Raise existing bank; form new Raise by 1.2m Road footpath South of Station New RC wall; form new Raise by 0.6m Road footpath Binn Wall (north) No raising of FDL needed, Repairs only only repairs to flood wall New Passage New sheet pile flood wall and 1.4m high glass panels; coast side of Severn Way path Severnside, North of Chestle Raise tidal flood bank Raise by 2.6m north Pill Northwick Warth Raise tidal flood bank; carries Raise by 2.6m Severn Way path Raise tidal flood bank; form Raise by 1.6m Old Passage: flood ramp in road; or direct new flood wall property level protection if more appropriate/acceptable
Further detail on the optioneering process is also provided in Appendix C.
The preferred intervention options for the ecological mitigation element of the project relate to operational considerations rather than spatial considerations, given that the areas identified for ecological mitigation were limited to Hallen Marsh and Northwick. At both locations, three operational approaches to providing a minimum of 85 ha of wetland habitat to meet the requirements of the Cresswell Study were identified:
Do Nothing: no compensatory habitat would be created at Hallen Marsh and Northwick, meaning alternative provision of compensatory habitat would be required elsewhere to allow future development in ASEA to come forward. Multiple, Connected Habitat Areas: creation of an open, diverse mosaic of new wetland habitat. Utilising site‐wide management of the rhines and removal of some of the hedgerows.
Doc v21 Last updated Nov 2017 Single Habitat Area: focus on creating specific habitats, e.g. one area of wet grassland and a separate area of open water habitat, which could be managed independently.
The Do Nothing scenario was rejected on the basis that five other sites had already discounted from delivering compensatory habitat prior to consideration of Northwick. The ‘multiple, connected habitat area’ approach was identified as the preferred approach because:
It maximises available habitat, therefore unlocking the maximum quantum of employment‐led development in ASEA. It will provide more ecologically diverse and functional habitat. Enable the rhine systems and associated ditches to be managed holistically, minimising flood risk. It will provide a more sustainable scheme, which can be constructed and managed more holistically than development of separate, potentially isolated habitat units.
1.7 Environmental Sustainability Considerations Environmental sustainability underpins the project, which combines the delivery of strategic flood defence infrastructure to safeguard and unlock economic activity in ASEA alongside ecological assets to provide mitigation against employment‐led development in ASEA. The strategic flood defence infrastructure will reduce flood risk to existing and future development in the area, linking environmental sustainability to economic growth and vitality. Simultaneously, the provision of ecological assets to meet the requirements set out in the Cresswell Study to provide appropriate habitat for wetland birds, will allow the full extent of proposed development in ASEA to come forward in a timely manner. Again, this demonstrates the linkages between environmental sustainability and economic growth and development that are central to the project.
The preferred options highlighted above reflect the most sustainable options for delivering the proposed flood defence and ecological assets. For example, the preferred alignment option for flood defence predominantly builds on existing structures, minimising demand for materials and maintenance requirements. Similarly, the preferred operational approach to ecological mitigation proposes to follow the ‘multiple, connected habitat area’ approach, which involves simpler and more sustainable construction and management. Further, there is potential to reuse some of the waste material generated in creating the ecological assets as part of flood defence works (e.g. bunds and embankments).
1.8 Equality and Diversity Impact Assessment It is a requirement that all schemes coming through for funding produce an Equality and Diversity Impact Assessment and to draw up a plan of action to address equality and diversity issues relevant to the scheme.
The project directly assists in facilitating the Strategic Economic Plan’s overall vision, underpinned by five strategic objectives:
1. Create the right conditions for business to thrive. Give confidence and certainty to our investors to attract and retain investment to stimulate and incentivise growth; 2. Enhance & protect our natural & built environmental assets to build our resilience to climate change;
Doc v21 Last updated Nov 2017 3. Create places where people want to live and work, through delivery of essential infrastructure including transport and housing to unlock suitable locations for economic growth; 4. Shape the local workforce to provide people with skills that businesses need to succeed and that will provide them with job opportunities; and 5. Ensure all our communities share in the prosperity, health and well‐being and reduce the inequality gap. The project will directly contribute to the achievement of objectives 1, 2 and 3. In addition, by providing necessary infrastructure to unlock land, it will also help indirectly to deliver objectives 4 and 5.
The approach to the Equality and Diversity Impact Assessment follows the standard format of other Assessments for projects within the area. The framework below was adapted to highlight how the project recognises that delivering excellence in Equality & Diversity is intrinsically linked to the successful achievement of the WoE 2030 Vision.
Figure 1.2. Achievement of the WoE 2030 Vision
Equality and Diversity and the ASEA Scheme
The project seeks to provide a 1:200 (0.5% AEP) standard of protection (SoP) from tidal flooding to the Avonmouth and Severnside Enterprise area in Bristol and South Gloucestershire. Wetland creation is included within the project to ensure that supporting habitats to the Natura 2000 Severn Estuary site are provided in order to mitigate the impact of industrial development.
The ASEA is expected to contribute significantly to achieving employment and economic growth over the next few decades. As well as safeguarding existing employment sites, developments within ASEA is expected to create close to 14,000 new jobs over the next 25 years, of which at least 6,000 new jobs are envisaged to be created in the next decade. However, the growth potential of the area is currently
Doc v21 Last updated Nov 2017 hindered by the ecological and environmental issues, which limit the scale of area available for development purposes within the ASEA. As such, investment in critical infrastructure to unlock development at ASEA is essential.
Appendix 1 of the West of England Guidance Note advises that it is important to recognise that equality and diversity will be more or less relevant to a Scheme depending on the aims of the Scheme in question. As the Scheme is primarily for flood defence works, equality & diversity issues are less relevant. Although the scheme intends to unlock land for future employment, this assessment can only consider jobs that relate solely to the Scheme. As such, equality and diversity issues will apply to construction jobs and the scheme once operational (primarily in relation to footpaths and accessibility).
It is clear that this project will contribute to the maximisation of impact in relation to the LEP identified Drivers of Growth – through specifically contributing in the area of ‘Place & Infrastructure’ and through indirectly impacting on the delivery of significant growth in respect of the “People – Knowledge, Economic, Skills and Social Inclusion” Driver of Growth; enabling the continuation of the development of skills to meet the requirements of employers in the West of England.
The LEP is clear on its strategic focus for Equality & Diversity and this Scheme complements and will contribute to the achievement of these strategic objectives:
Table 1.5. LEP Equality and Diversity Impact Assessment Strategic Objectives Source: LEP Strategic Economic Plan Strategic objectives Scheme Contribution Driver of Growth: “Place & Infrastructure” ‐ The removal of particular local barriers to work through our People and Skills Driver of Growth. ‐ The use of inclusive design principles to meet the key components of successful neighbourhoods which include: Resident empowerment, Access and connectivity, Services and amenities, Built and natural environments, Social networks/well‐being, Housing. ‐ Supporting the diversity of employment opportunities which is a critical component of success. Driver of Growth: “People – Knowledge, Economic, Skills and Social Inclusion”
‐ Ensure the needs of all social groups are met through wide‐ranging activities to improve employability.
By unlocking the site for a range of employment development, the project will make a strong but indirect contribution to promoting equality and diversity. Development will create new opportunities on site for access to employment opportunities and open space. It will play a fundamental part in improving accessibility for the residents living within the area, parts of which contain pockets of long‐ standing deprivation and significant minority ethnic populations.
Aims, Objectives and Outcomes
Doc v21 Last updated Nov 2017 The overall aim is to ensure that equality & diversity principles and values are applied across the project, and actions proactively taken which contribute to maximising success in delivering the ASEA scheme. No negative impacts have been identified in relation to any equalities groups.
Table 1.6. Impact assessment – objectives and outcomes Source: CH2M Objectives Key Actions Intended Impact To ensure that Consultation with local The scheme design is successful consultation in relation communities and representative in maximising accessibility for all, to the scheme design is groups, will identify any required for example, taking into account appropriate and impacts design modifications required to the needs of disabled residents upon the scheme design meet the needs of these groups. and visitors. where appropriate. For example, path diversions and the impacts on disabled people and older people. To ensure that best All aspects of the scheme design The scheme design is successful practice in inclusive will be reviewed to ensure in maximising accessibility for all, design forms an integral compliance with best practice in for example, taking into account and central part of the inclusive design. the balanced needs of disabled project design. residents and visitors.
To ensure that equality & Appropriate checks within the The successful construction diversity questions are procurement process will be contractors have in place policy specifically built‐in to utilised. and practice which demonstrate procurement activity in the importance of embedding relation to construction equality & diversity into all contracts. aspects of business life.
The above objectives will be continuously monitored to understand both progress and the impact of these actions on the achievement of our project objectives.
2 Economic Case
2.1 Economic Appraisal An economic appraisal has been undertaken based on guidance provided in the following documents:
West of England LEP One Front Door Programme – Support Manual (including the ‘Impact Guidance Note’). Joint Defra/EA FCERM R&D programme’s (project FD2662) ‘Flood and coastal erosion risk management and the local economy’. HM Treasury ‘The Green Book’. Homes and Communities Agency ‘Additionality Guide’ and ‘Employment Densities Guide’.
Further, sections of the analysis (particularly in relation to future economic development unlocked) pivot from the existing Amion Model established in 2012/13 to support the Growth Incentive element of the City Deal.
Doc v21 Last updated Nov 2017 Within this context, the package of benefits associated with the scheme arise through three primary routes:
Construction phase job creation and GVA uplift associated with implementation of construction works; Safeguarding current economic activity in the form of jobs and GVA at existing businesses that will benefit from reduced flood risk; Unlocking/Safeguarding land subject to future/recent development resulting in job creation and GVA uplift.
A summary of the economic analysis results is presented below. More detail on the methodological approach and outputs generated by the economic analysis are presented in Appendix D.
Construction Phase Impacts
The main economic impacts generated in the construction phase relate to direct and indirect employment creation and gross value added (GVA) generation. The direct effects capture the change in employment and economic output attributable to the design and build process itself. The indirect effects capture the knock‐on implications for the supply chain that supports construction industries and benefits from increased expenditure within that industry.
Direct GVA impacts: Direct GVA impacts are calculated through the application of best‐practice turnover‐to‐GVA ratios provided in the West of England LEP’s Support Manual. The Support Manual recommends a range of ratios between 0.37 and 0.43 to convert turnover to GVA . Applying this ratio to the scheme turnover of
Direct Employment Impacts: Direct employment impact is calculated through the application of best‐ practice ‘cost‐per‐job’ benchmarks listed in the Support Manual. The guidance indicates that £90,000 (2014 prices)5 of infrastructure investment is required to sustain one full‐time equivalent (FTE) employee. .
Indirect GVA Impacts: It is likely that much of the construction contractors’ supply chain requirement will be met in the local area. Most expenditure will therefore be locally based and support local firms, so the upper‐end of the multiplier range suggested by the Support Manual guidance has been used.
Indirect Employment Impacts: Similarly, to supply chain requirements, it is likely that much of the construction contractors’ employment requirement will be met in the local area. Hence, the upper‐ end of the multiplier range in the guidance was therefore used.
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Operational Phase Impacts
5 Note that this benchmark has been converted to 2016 prices for consistency with other price bases used in the analysis. Therefore, the benchmark used is actually £91,263 of infrastructure investment per employee.
Doc v21 Last updated Nov 2017 Existing Economic Activity: The scheme will act as a public good to safeguard the following scale of floorspace, employment and GVA across ASEA based on a 100‐year appraisal period:
Around 575,000 sq m of employment floorspace will benefit from reduced flood risk relative to the Do Nothing scenario; Around 13,500 jobs will benefit from less disruption and temporary/permanent closure as a result of reduced flood risk relative to the Do Nothing scenario
Future and Recent Economic Development: The scheme will address market failure related to: imperfect competition, development viability and the planning and environmental requirement to provide flood defence and ecological mitigation, to safeguard and/or unlock the following scale of recent and future economic development across ASEA by the end of the City Deal (2038):
Net Impacts: Following the application of appropriate factors of additionality (e.g. deadweight, leakage, displacement, substitution and multiplier effects), the gross impacts outlined above translate to the following net additional impacts:
Reduction in Capital Damages to Existing Properties
Doc v21 Last updated Nov 2017 The project will also reduce flood risk associated with existing commercial and residential properties, resulting in lower anticipated capital damages to buildings. As the monetised benefits associated with this impact of the project are reported in the FDGiA outline business case, they are not incorporated into the value for money assessment outlined below. That said, the monetised values are reported below for completeness:
Business Rates Growth
Based on the quantum of development anticipated at ASEA, the development area is assumed to generate in business rates in the reference case, increasing to over in the intervention case. The full scale of business rates generated in the reference and intervention cases is well above the baseline business rate value of £147m generated at ASEA until the end of the City Deal. This suggests that ASEA could contribute some in business rates, above and beyond the baseline value, in the reference case. This contribution could increase to in the intervention case. These metrics imply gross additional business rates of (constant prices) in the intervention case. When discounted and converted to net additional business rates as a result of intervention, the scale of business rate uplift is equivalent to across the appraisal period.
. Note that the above analysis is only included to demonstrate that the project will be a net contributor to the City Region’s Growth Incentive and related Economic Development Fund. The business rate growth is not incorporated into the value for money analysis below. More detail on the generation of business rates is provided in Appendix D, alongside the rest of the detailed economic analysis. 2.2 Value for Money Statement The monetisable scheme benefits outlined above can be summarised as follows:
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Combining these various benefit streams, the total scheme benefits amount to from an economic development perspective. Compared to total scheme costs to , this scale of benefits generates a BCR in the region of This suggests the project represents very good value for money. Table 2.1. Value for Money Assessment Source: CH2M Total project cost £1.9 million expenditure to date
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Grant sought (EDF/LGF/RIF) (further to £1.9 million expenditure to date) Net Quantified Benefits Construction Stage Employment: full‐time equivalent jobs during the construction stage (direct and indirect) Construction Stage GVA: ) Safeguarded Employment at existing development: full‐time equivalent jobs benefitting from reduced business downtime Safeguarded GVA at existing development:
Net Unlocked/Safeguarded Employment at Future and Recent Development Sites: full‐time equivalent jobs Net Unlocked/Safeguarded/Accelerated GVA at Future and Recent Development Sites: VfM indicator*
Table 2.2. Summary Table of Assumptions Source: CH2M Criterion of assessment Assumption Jobs Calculated as follows: Construction stage employment: based on cost per job benchmarks provided in the LEP’s ‘Impact Guidance Note’ Safeguarded employment and unlocked employment: based on floorspace data provided by SGC and BCC, converted to full‐time equivalent jobs using the HCA’s Employment Densities Guide GVA Calculated as follows: Construction stage GVA: based on GVA/Turnover ratio benchmarks provided in the LEP’s ‘Impact Guidance Note’ Safeguarded GVA and unlocked GVA: based on GVA per Employee benchmarks sourced from the Annual Business Survey, weighted by ONS sub‐regional productivity data to suit the specific West of England context.
Please see Appendix D for further details on the assumptions, methodological framework and calculations underpinning the economic analysis presented above.
Doc v21 Last updated Nov 2017 3 Financial Case
3.1 Chief Financial Officer sign off Appendix X presents the Section 151 Office sign‐off letter from the Chief Financial Officers of SGC and BCC stating: All relevant financial approvals are in place to deliver the project as set out in the Full Business Case. All appropriate financial due diligence will have been undertaken in respect of the Full Business Case. Recognition that they are responsible and accountable for ensuring that the project delivers good value for money in the use of public resources, that being the suitability and effectiveness of the project as well as the economic growth and wider societal outcomes achieved in return for the public resources received.
3.2 Scheme Cost The projected costs for the project are given in Table 3.1. Note that this FBC submission precedes the outcome of the tender process, which is scheduled for Summer 2018. As such, the cost and budget profile information reported here is based on best current estimates based on the designs submitted for planning. A more definitive view on costs and budget profile will be available following the tender returns in September 2018; it may be possible to incorporate the details of this process into the FBC prior to final approval. The tender process will also provide greater detail on construction programme and process. This will inform greater certainty on the ‘other scheme costs’ cost category, which are currently underpinned by initial views on likely construction programme and process. Greater detail on the financial model for the current analysis is provided in Appendix E. Optimism Bias and other risk budgets are calculated using a Monte Carlo analysis, following a risk workshop at which all the key partners were represented, including SGC, BCC, EA and the WEM Lot 3 and WEM Lot 4 suppliers.
The cost figures presented in Table 3.1, with the funding profile provided in Tables 3.2 to 3.4 are subject to change in line with an increasingly refined cost model as the project moves through the tender process, with the construction cost subject to more detailed pricing and programming as part of that process. Please see Appendix E for more details. Table 3.1. Cost Elements Source: CH2M
Total projected Amount to be eligible Cost Heading claimed (£ expenditure ‘000s) (£’000s) Expenditure to date Business Case Development £1,900 £1,900 Expenditure to date Sub‐Total £1,900 £1,900 Future Expenditure
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In total, £1.9 million of LEP funding has already been spent to date.
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Also note that post‐construction maintenance costs for ecological mitigation is incorporated for five years under the ‘Environmental Mitigation for Areas 4&5’ line item in Table 3.1. After that point, maintenance costs for ecological mitigation will be dependent on what kind of management plan is implemented by the SGC and BCC. At this point, it is understood that a bridging payment covering five years (and captured above) would later be replaced by environment stewardship funding.
. An Outline Business Case for FDGiA funding was submitted earlier this year and is currently awaiting review by the EA’s Large Project Review Group (expected mid‐summer).
3.3 Spend Profile and Funding Sources At this stage, and in advance of the tender process anticipated to conclude in September 2018, the expenditure profile for the project is assumed to mirror the anticipated budget profiles established by SGC and BCC. Future capital expenditure therefore extends over five years between 2018/19 to 2022/23. A more definitive view capital expenditure profile will be available at the end of the tender process in September 2018; it should be possible to incorporate the details of this process into the FBC prior to final approval.
Revenue spending is profiled from 2018/19 for a period of sixty years, in line with EA requirements. The revenue spending is broadly linear across the period.
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Table 3.2. Capital Spend (£’000s) Source: CH2M
Pre‐2018 1 LEP £1,900
Doc v21 Last updated Nov 2017 EA/ FDGiA Total £1,900
Table 3.3. Revenue Spend (£’000s) Source: CH2M
Pre‐2018 LEP £0 599
EA/ £0 FDGiA Total £0
Table 3.4. Total Spend (£’000s) Source: CH2M
Pre‐2018 LEP £1,900
EA/ £0 FDGiA Total £1,900
Doc v21 Last updated Nov 2017 4 Commercial Case
4.1 Procurement The recommendation of the ASEA Strategic Directors Board is that the EA should act as project delivery lead for the design and build stage of the project. The main basis for the recommendation relates to the operational experience gained through delivery of EA flood risk programme. The intent is that EA will take on the employer project management function to include responsibility for procurement and project/contract management. The procurement exercises for the required works and services would be delivered in line with the EA Financial Scheme of Delegation ensuring value for money and OJEU compliance. It is proposed that EA procure the construction contract through their Water and Environment Management (WEM) Framework (Lot 4: Asset Delivery).
The WEM Framework provides access to the best suppliers in flood and coastal risk management. It is a commercial agreement between the Environment Agency, consultants and contractors ('suppliers') with agreed terms for the award of individual contracts to deliver projects for Flood and Coastal Risk Management (FCRM). Lot 4 covers construction works, coastal works (e.g. beach nourishment, dredging and coastal structures) and design and build. The Framework is deemed appropriate for adoption on this project for the following reasons:
The Framework was established to be the UK’s primary vehicle for delivery of significant flood risk management projects. Lot 4 was specifically set up to deliver large scale flood defence construction schemes. The Framework has already been through a full open tender process to identify the best suppliers to deliver large scale flood mitigation projects. The successful contractor would be awarded via a mini‐competition process with five suppliers. Framework use aligns to the UK Government Construction Strategy. Neither SGC nor BCC have an equivalent WEM Framework. WEM is therefore a more efficient, tried and tested route to market. The Framework has been procured in accordance with EU regulations, including supply chain management and engagement with locally‐based SMEs. EA has statutory powers of entry available for much of the land associated with the ASEA project. EA is unable to transfer such powers to SGC or BCC commissioned contractors without significant legal process and agreement.
The WEM Lot 4 design and build contract will be awarded under a NEC3 ECC Option C target cost contract with activity schedule. The principal suppliers for appraisal and outline design of the project are:
CH2M (WEM Lot 3): modelling, appraisal, outline design, OBC report and tender pack design and build contract; and for the ecology project also the detailed design BMM JV (WEM Lot 4): ESE contractor services to develop the works methodology, confirm buildability and provide practical site investigation advice and input into costing of options, risks register and construction programme. Arcadis: cost and risk management services.
Doc v21 Last updated Nov 2017 In accordance with the procurement strategy a competitive tender process involving WEM Lot 4 suppliers in bidding for one contract is scheduled from April to October 2018. Following approval of the FDGiA FBC the contract will be let to the preferred WEM Lot 4 supplier.
On return of tenders, the project team will undertake a detailed cost review of the tenders against each other and also against a Project Cost Tool (PCT) pre‐tender estimate to establish the most economically advantageous offer. The project team will also undertake a detailed quality review of each of the tenders to establish the best quality offer. The project team will then recommend to the Flood Defence and Ecology Group the preferred WEM Lot 4 supplier.
The procurement timescales are given below. Following construction of the works a minimum two‐ year defects liability period is scheduled, which is necessary to accommodate the landscaping works and planting establishment period.
Table 4.1. Procurement Timescales Source: CH2M
Procurement task Start Complete Pre-procurement engagement February 2018 March 2018 FDGiA OBC approval – OGC Gateway 2 April 2018 June 2018 Preparation of tender pack (incl. Works Information) April 2018 July 2018 Tender issue July 2018 July 2018 Tender return October 2018 October 2018 Tender evaluation October 2018 November 2018 Award recommendation / approvals December 2018 December 2018 FDGiA FBC approval – OGC Gateway 3 December 2018 December 2018 Contract award – commence design only December 2018 December 2018 Instruction to commence construction December 2018 December 2018
4.2 Operation and Financial Viability The flood defence element of the project will be operated and maintained by the EA as part of their statutory responsibility to manage flood risk and maintain flood defence assets. Maintenance responsibility may be devolved to organisations such as Bristol Port and Network Rail where assets exist on their land and impinge on operations. Where possible, maintenance will be managed using the EA’s existing processes, such as the Flood and Coastal Risk Management Operational Framework.
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The financial viability of the future LEP funding grant of is demonstrated through anticipated net additional business rate uplift of Section 2.1). This demonstrates that LEP funding will generate a significant increase in revenue to the West of England LEP as part of the Growth Incentive element of the City Deal. This revenue stream can be recycled as part of the Economic Development Fund to allow investment in other economic development priorities across the wider West of England area.
4.3 Social Value Act The Social Value Act requires people who commission public services to think about how they can also secure wider social, economic and environmental benefits. Such Social Value benefits are expected to be factored into the pre‐procurement phase of project development, allowing the issues to be embedded into project design. Within the context of the current project, factors such as the potential social, environmental and economic impacts of the scheme have been appraised from the outset of Full Business Case development. Considerable consultation and engagement has also been undertaken throughout the process to ensure opportunities for Social Value benefits from the project are maximised.
SGC’s Social Value Policy defines Social Value as the “the additional benefit to the community from a commissioning/procurement process over and above the direct purchasing of goods, services and outcomes”. The project is well‐aligned and supports SGC’s Social Value Policy. Specific Social Value benefits that the project could support include:
Creating skills and training opportunities e.g. apprenticeships – the project could help deliver this Social Value benefit by providing employment, skills and training opportunities for local people during the construction stage. Promoting and supporting local innovation to enhance local productivity and enable local businesses to adapt to global changes that may affect competitiveness – the project could support this Social Value benefit by reducing flood risk for existing businesses and provide the conditions for growth and enhanced productivity at new businesses. Improving market diversity – the project could help achieve this Social Value benefit by providing commercial premises for a range of businesses. Providing additional opportunities for individuals or groups facing greater social or economic barriers – the project could support this benefit by enabling significant job creation, which will improve employment opportunities for residents across the West of England. Ensuring all council led projects, plans and programmes make a positive contribution to the creation, protection, enhancement and management of green infrastructure – the project will help deliver extensive green infrastructure in the form of 85 ha of wetland habitat.
Doc v21 Last updated Nov 2017 5 Management Case
5.1 Promoter and Delivery Arrangements The project is being jointly promoted by the two local authorities in which ASEA lies: SGC and BCC. The EA are delivery partners for the project, performing the employer project management function to include responsibility for procurement and project/contract management (as outlined in Section 4.1). The intent is that project oversight will be via the three existing project partners (SGC, BCC and EA) although a new Collaborative Agreement will be required to outline the basis of the arrangements (this will be set in place in time for the full application). It is envisaged that a draft version of the Collaborative Agreement will be developed over the summer and may be available prior to final approval. As outlined above, delivery arrangements for the current stage of the project involves the following principal suppliers for appraisal and outline design:
CH2M (WEM Lot 3): modelling, appraisal, outline design, OBC report and tender pack design and build contract; and for the ecology project also the detailed design. BMM JV (WEM Lot 4): ESE contractor services to develop the works methodology, confirm buildability and provide practical site investigation advice and input into costing of options, risks register and construction programme. Arcadis: cost and risk management services.
Delivery arrangements for the construction stage, including detail on the preferred contractor, will be available towards the end of 2018, after submission of this FBC.
5.2 Project Governance and Delivery This project is a partnership between SGC, BCC and EA. The project will help to unlock the economic potential of ASEA and protect the existing communities from flooding. The governance structure comprises the Strategic Directors Board (SDB) and Delivery Board. The Strategic Directors Board (SDB) comprises members of SGC, BCC, West of England LEP and the EA. Its role is to provide strategic guidance; programme prioritisation and decision‐making via bi‐monthly meetings. The SDB will provide overarching authority for the ASEA programme. The SDB will need to make decisions regarding investment and ensure on‐going overall alignment of the programme. Some of the duties and responsibility of the SDB include: Authorise the organisational strategic direction against which the programme is to deliver. Provide and ensure the continuing organisational context for the programme. Authorise funding support for the programme. Resolve strategic and directional issues between projects, which need the input and agreement of senior stakeholders to ensure the progress of the programme (and any change requirements therein). Authorise the progress of the programme and projects against strategic objectives. Provide continued commitment and endorsement in support of the programme objectives at executive and communications events. Provide advice and support to the Senior Responsible Officer (SRO). Ensure the work of projects and sub‐groups is coordinated and to provide appropriate advice and guidance. Co‐ordinate and monitor effectiveness of resources deployed to develop ASEA.
Doc v21 Last updated Nov 2017 Co‐opt additional members from time to time and shall invite any number of persons as are required to inform the Board and attend to business on meeting agenda.
The Delivery Board consolidates various related bodies including the Flood Defence and Ecology Groups and the ASEA Growth Board and consists or representatives from SGC, BCC and the EA. The purpose of the Delivery Board is to help realise the agreed outcomes and benefits for the ASEA programme area. The Delivery Board signed off this draft LEP FBC at the monthly meeting on 25th January 2018. Some of the duties and responsibility of the Delivery Board include: Provide resource and specific commitment to support the SRO, accountable for successful delivery of the programme. Define the acceptable risk profile and risk thresholds for the programme and its constituent projects including project tolerances for exception reporting with respect to costs, risks, issues and dependencies. Receive and comment upon exception reports from all projects associated to the Board. Seek to resolve strategic and directional issues between projects. Develop and make available to each project, generic document templates e.g. risk and issues register, project business case etc.
All other stakeholders (e.g. Natural England) lie outside the formal governance structure, but provide useful support and insight into project development. Further guidance on project governance and delivery is outlined in the Collaborative Agreement provided in Appendix F. 5.3 Programme Plan Note that this FBC submission precedes the tender process, which is scheduled for Summer 2018. As such, the Programme Plan reported here provides an indicative overview of anticipated milestones for the project only. A more definitive view on the programme plan will be available at the end of the tender process in September 2018; it should be possible to incorporate the details of this process into the FBC prior to final approval. Also note that programme changes following the tender process could have implications on the ‘other scheme costs’ cost category, given that the cost of some of the other scheme costs will be driven by the timing, scale and location of construction activities determined by the programme. Again, it is expected that more specific information derived from the tender process can be incorporated into the FBC prior to final approval.
Table 5.1. Programme Plan Source: CH2M
Milestone completion dates Baseline month/year Draft Full Business Case Submission Feb 2018 Final Full Business Case Submission Oct 2018 Contract Award Nov 2018 Construction Start Dec 2018 Readiness for Service Aug 2023 Construction Finish Aug 2023 Contract Completion Feb 2024 Project Closure Aug 2024
Doc v21 Last updated Nov 2017 5.4 Risks, Constraints and Dependencies The main risks and risk mitigation measures associated with the project are defined as: Design flood defence levels: The outline designs are based on the current estimates of extreme water levels and wave / water level joint probabilities for the Severn Estuary. Design levels have considered both forthcoming guidance on uncertainty allowances and the more conservative approach of the National Planning Policy guidance. Future update of these estimates may come through before detailed design that possibly necessitate a change in flood defence levels. If this situation arises prior to award of design and build contract, a Project Board meeting will be convened to provide guidance to the project team on the way forward. Communication with partners: Communication needs to be clear and unambiguous to ensure aims and objectives are fully understood. From the outset, in developing the scheme the key partners (South Gloucestershire Council, Bristol City Council and Environment Agency) have worked closely together and with key stakeholders, including the Lower Severn Internal Drainage Board, Natural England, Highways England and Network Rail, and the public. Further consultation is planned so that feedback can help shape the detailed design. Consents and approvals; notably Natural England and planning permission: The project team continue to work closely with partner organisations to mitigate this. A Habitats Regulations Assessment (HRA) has been completed and approved in principle by Natural England. The project team are drawing on our experience of delivering similar projects that required a HRA (e.g. Exeter flood defences) to plan for and manage these risks. Working on linear, constrained sites (e.g. Avonmouth docks): This is likely to result in disruption to the docklands, businesses and the public. The project team will work closely with the preferred design and build supplier to understand and minimise the likelihood and impact of any disruption particularly during detailed design.
To date, the project team have managed some significant project risks, including: Availability of information relating to contaminated ground, unfavourable ground conditions and presence of UXO (unexploded ordnance) – the project team have undertaken geotechnical investigations that identified variation in soil strength and settlement parameters and for this reason the risk budget includes provision for greater than expected settlement. Construction programme: drafted by the ESE contractor (BMM JV) to inform the milestones outlined in this OBC, which allows for expected environmental constraints related to working close to the Severn Estuary SPA and likely poor ground conditions during wet winter periods. The actual construction programme will be determined by constraints to manage environmental risks and the requirements of Bristol Port Company in particular, as the construction works need to be managed flexibly to avoid disruption.
Project risks have been identified by the project team and management actions for the key risks have been assigned to the relevant organisation within the team. The risks are regularly reviewed and the progress against the management actions monitored. The key project risks are given in Table 5.2.
Table 5.2. Key Project Risks and Ownership Source: ABS, ONS, CH2M Key Risks H/M/L Owner Mitigation
Doc v21 Last updated Nov 2017 1 Potential solutions involve H BCC, Appraisal and implementation is staged land operated by protected SGC, with likely phased business cases to undertakers EA mitigate risk to whole project. Consultation with protected undertakers carried out to ensure support of proposed solutions.
2 Aligning funding streams from H BCC, Ensure procurement approach does not Councils and Environment SGC, rely on achieving a specific programme. Agency EA Aim to have both Lot 3 and Lot 4 WEM suppliers under contract early in the process to make it easier to adapt.
3 Dealing with inland drainage H BCC, Continue to engage with the Lower SGC, Severn IDB to ensure they support the EA proposals. We have established that outfall capacity is more than adequate except there might be issues at Cotteralls outfall (to consider further).
4 Other infrastructure being H BCC, We will have to keep abreast of other built within ASEA SGC, development, notably a new junction on EA M49 that might impact on drainage and topography and a new high voltage connection project for Hinkley Point C around the Hallen Marsh site – to be managed by change control rather than contingency.
5 Differing political drivers, local H BCC, Draft legal agreement between EA, SGC elections etc SGC, and BCC acknowledges that each EA organisation works to own rules and instructions. Any differences will be escalated early to the ASEA Strategic Directors Board. Allow time for organisations to sign‐off.
6 Major Flood during project H BCC, We have 3 organisations within which to development changing SGC, share additional work. But there remains political drivers. Could put EA a risk requiring contingency planning and extra strain on resources. knowledge of where additional resources could be provided.
7 Construction risks: H BCC, We have considerable ground Unforeseen ground SGC, investigation from previous projects conditions, including soft EA which has been added to. We anticipate ground, particularly in the further specific ground investigation and coastal floodplain, and hard innovative ground works at detailed ground or obstructions design stage. affecting piling works.
8 Construction risks: H BCC, We are designing defences around what
Doc v21 Last updated Nov 2017 Unsuitability of site‐won soil SGC, material is available locally, however, the for reuse in construction or EA requirement for import of material is still need for soil treatment. likely.
9 Environmental risks: discovery H BCC, We have carried out a geophysical of significant archaeology. SGC, investigation and allowed time for D&B EA contractor to undertake more fieldwork.
10 Environmental risks: discovery H BCC, We have identified 1ha of new inter‐tidal of unexpected rare species, SGC, area at Cake Pill that can be created for unforeseen invasive species; EA general ecological mitigation. Natural England/NGOs may We are addressing estimated losses of require inter‐tidal intertidal habitat due to coastal squeeze compensation. through provision of like‐for‐like habitat at Steart, Alvington & Plusterwine. We will limit risks associated with rare / invasive species and potential for temporary incursions within N2K sites at construction stage through the Construction Environmental Management Plan and supervision by Ecological Clerk of Works.
11 Discovery of contaminated H SGC Treat on site or remove to licensed tip land in the port and other BCC EA historic industrial areas of the project, landfill areas, together with contamination on or on adjacent to railway land. Contaminants (eg. asbestos, hydrocarbons) in areas proposed for piling or excavation works
12 Discovery of unknown M SGC Develop a single combined services services affecting scheme BCC EA record. Geophysical survey of potential design and/or injury to clashes and positive identification of personnel services prior to detailed design
13 Adverse Weather Conditions H SGC Aim to construct earthworks in dryer delaying scheme construction BCC EA months. Allow for reduced productivity in ‐ prolonged wet or cold programme and budget conditions.
14 Flooding over the working M SGC Maintain capacity of existing viewed area, but less than a 1:10 BCC EA rhines and outfalls. Ensure ESE contractor probability event, which is and tendering permanent works covered by Major Risk B7‐2‐ contractors understand the requirements Loss of material, degradation, of the scheme. Allow for downtime in replacement and clean‐up programme and budget
15 Need for maintaining current M SGC Ensure ESE contractor and tendering
Doc v21 Last updated Nov 2017 SoP during construction phase BCC EA permanent works contractors understand not properly understood. the requirements of the scheme. Allow Damage to completed flood for reduced productivity in programme defences after contractual and budget completion but prior to establishment of vegetation
16 Influential stakeholder(s) H SGC Clarify uncertainties & scheme details object to scheme proposals BCC EA with NE, SGC, BCC, HE, IDB and others, prior to submitting formal planning application. Implement a staged or Iterative design approach
17 Stakeholder feedback during M SGC Clarify uncertainties & scheme details detailed design requires BCC EA with NE, SGC, BCC, HE, IDB and others, incorporation of more prior to commencing detailed design. expensive defence‐types, habitat types or accommodation works in order to gain approvals and consents
18 Need for extensive rock M SGC Allow for additional design and armour BCC EA consenting costs. Also allow for cost of more expensive defences at embankments.
19 Project is required to install M SGC Clarify uncertainties & scheme details piles from the railway due to BCC EA with NR, NE, SGC, BCC, HE, IDB and environmental constraints. NR others, prior to submitting formal object to scheme proposals. planning application Approval to work on NR land is initially refused
20 Land access difficulties M SGC Early liaison with landowners. Issue notice including Bristol Port (access BCC EA of entry. Make risk budget allowance for to works and procurement of additional temporary/permanent access site compounds). routes and reduced productivity
Risks ownership has been allocated to the party best placed to manage a given risk. A detailed project risk register, produced by the WEM Lot 3 supplier following a risk workshop involving South Gloucestershire Council, Bristol City Council, Environment Agency, ESE contractor and NEAS, provides more comprehensive detail on the current approach to risk management (see Appendix G). Risks are apportioned between parties, covering those that arise in planning, design, implementation, construction and any residual risks. The general principle followed is that risk is passed to the party best able to manage them, subject to value for money. Table 5.3 sets out a proposed risk allocation matrix for the flood defence project. For some shared risks, the majority of the risk will be allocated to the supplier. Table 5.3. Risk Transfer Matrix – Potential Allocation Source: CH2M
Doc v21 Last updated Nov 2017 Risk item EA SGC/BCC Supplier Shared Design risk √ √ √ √ Construction / development risk √ √ √ √ Transition and implementation risk √ √ √ √ Availability and performance risk √ √ √ √ Operating risk: post scheme √ √ Termination risks √ √ Technology / obsolescence risks √ Residual value risks √ √ Financing risks √ √ Legislative risks √ √
For the main design risk of unknown ground conditions in the project area, at tender stage, tenderers will be provided with geotechnical assumptions to base their price upon. This will enable all tenderers to price the flood defence works based on the same assumptions and therefore the tenders can be evaluated on an equal basis.
5.6 Service Diversions A list of major service diversions required as part of the project are listed below. The costs associated with managing these diversions is incorporated into the cost estimates provided in the Section 3. As Cat 3/4 statutory undertaking enquiries are typically valid for three months, to avoid abortive work, such information will be collated in summer 2018 to ensure validity at the time of FBC approval in Autumn 2018.
Table 5.4. Service Diversion Summary Source: CH2M
Location Description
Chestle Pill LV Power Supply to Penstocks may clash with proposed RC defence wall
A403 (South of New Water supply, HV electric and BT all present in the verge next to the road and at Pill) least one of these is likely to require diversion to enable piling. Assume twin HV needs diversion for costing
Doc v21 Last updated Nov 2017 Chittening Warth, Twin HV cables alongside railway may clash with embankment north of Stupp Pill
Northern Harbour Telecom cable alongside harbour arm may clash with RC wall Arm ‐ Dock Entrance
Avon Frontage ‐ Telecom cable at port boundary may clash with RC wall within port
Lamplighters Marsh Optical Fibre Telecom cable next to railway may clash with sheet piles, but probably within railway boundary and not affected. Assume sheet piles could be diverted to avoid cable if necessary.
5.7 Engagement and Consultation The project team have engaged with statutory and non‐statutory stakeholders, operators, businesses, landowners, the public and EA, SGC and BCC internal teams. As part of the engagement process, a number of stakeholder sub‐groups have been established and approached at key project stages. Two stakeholder meetings and a round of public exhibitions and roadshows have also been held. Feedback from the engagement process has helped to shape the preferred options developed during the appraisal stage. A summary of feedback from the engagement process is provided in Appendix H alongside a recent project newsletter published as part of the engagement and consultation effort. The Preliminary Environmental Information Report (PEIR) has been consulted on internally and externally. The project team have engaged with Natural England on the Habitats Regulations Assessment. The Water Framework Directive assessment has been through an internal Environmental Agency engagement process with relevant specialists. The project team will continue this engagement as it works through the detailed design phase of the project as there is opportunity for partners and the local community to shape the final design. 5.8 Project Assurance The full programme of works within ASEA comes under the assurance of the Councils involved – SGC and BCC. From an EA perspective, the Large Project Review Group (LPRG) will assure the business case for the flood defence elements to satisfy requirements of FDGiA. The project programme includes sufficient time allowance to gain approvals as required from the governance groups involved in the project. This includes the Strategic Directors Board and Delivery Board. Note that the Delivery Board approved this draft version of the LEP FBC during their meeting on 25th January 2018. 5.9 Monitoring and Evaluation
Scheme: ASEA Ecology Mitigation and Flood Defence
Doc v21 Last updated Nov 2017 1. Scheme background and context Provide a short description of the scheme, including costs, the delivery timeframe and an explanation of the wider delivery context.
The project will deliver an integrated flood defence solution and ecological assets that will help to unlock the development potential of ASEA. The flood defence solution represents a hybrid scheme providing protection to a 1 in 200‐year (0.5% AEP) SoP based on a 2076 or 2098 design level in different locations. EA regulations state that the minimum level of flood protection should meet a 1 in 200‐year (0.5% AEP) SoP; therefore, the project meets (and in some locations exceeds) this requirement. A 2098 design level will be provided south of Binn Wall, where enhanced defence would maximise protection of ASEA. North of Binn Wall, a 2076 design level will be sufficient and help to control costs and reflect the reduced threat of flooding from this area affecting ASEA.
Ecological assets will be provided in the form of wetland habitat at two locations within the locality (Hallen Marsh and Northwick). The ‘multiple, connected habitat area’ approach to wetland creation will be adopted. The ecological assets are required to compensate for loss of habitat as a result of encroachment from employment‐led development on ASEA, rather than construction of flood defence infrastructure directly.
Milestone completion dates Baseline month/year Actual completion Draft Full Business Case Submission Feb 2018 Final Full Business Case Submission Oct 2018 Contract Award Nov 2018 Construction Start Dec 2018 Readiness for Service Aug 2023 Construction Finish Aug 2023 Contract Completion Feb 2024 Project Closure Aug 2024
Doc v21 Last updated Nov 2017 2. Logic Model Complete a logic model to reflect the project scope i.e. all the activities covered by the investment. Ensure also that there is a clear progression between the steps in your logic model. State assumptions between the investment and the predicted outcomes and impacts. For outcomes relating to direct jobs creation, please provide an annual profile of jobs created and clearly state the time period over which net additional jobs and GVA will be created. Please define the impact area of the intervention ie West of England or other geographical scale. (indicative 350 words)
Doc v21 Last updated Nov 2017 Logic Model
Context and Rationale The strategy is closely aligned to a range of national, sub‐regional and local economic and planning policy. The National Planning Policy Framework seeks to promote sustainable economic growth and reduce environmental threats posed by issues such as coastal flooding and climate change. ASEA is highlighted as one of the LEP’s most important economic development opportunities within the Strategic Economic Plan. However, flood risk is acknowledged as a key constraint to development, alongside the presence of internationally important habitat. Development at ASEA is also considered as a strategic priority in the draft West of England Joint Spatial Plan and the emerging Local Plan’s for SGC and BCC. The suite of local planning policy documents also recognises the significant environmental, flood risk and infrastructure constraints that could hinder development at ASEA. Market failure exists in the form of development viability and imperfect competition that arise partly because of the 1957/58 planning consents. These consents allow some development in ASEA to proceed based on a legacy planning approval that excludes any requirement to meet current flood defence and ecological standards. Therefore, the financial burden of flood defence and ecological mitigation would fall disproportionately on development sites outside of the 1957/58 planning envelope, eroding development viability and constraining development of the site. Further, the project will provide public assets which will act as a public good, protecting existing commercial and residential properties from flood risk. Objectives Resources/ Input Activities Outputs Direct & Indirect Outcomes Impact The aims/ objectives of the scheme are: In order to achieve the set of activities to In order to address the aims and objectives We expect that, once accomplished these We expect that if accomplished these We expect that if accomplished these (Ensure that all aims/objectives are SMART) fulfil these aims/ objectives we need the we will accomplish the following activities: activities will produce the following outputs will lead to the following change activities will lead to the following changes following: (What will the money be used for? e.g. deliverables: e.g. new products or services, skills, in service, organisation or community: (Resources should not be limited to money construction, project management, (Provide measurable outputs e.g. length of behaviour, new business/contracts, etc: (quantitative economic impacts e.g. indirect e.g. grant, match funding, in‐kind, project equipment/fit out, etc): new road/cycle path, m2 of space (Ensure that all outcomes are SMART and jobs and/or GVA to be cross‐referenced team, specialist support, etc. The inputs constructed/refurbished, number of relevant to the aims/objectives to allow for with FBC as appropriate) define the scope of the project being businesses supported, learners engaged, attribution; distinguish between direct and considered in the logic model) etc) indirect outcomes) £1.9 million has already been spent on 404,000 sq m of net floorspace at New or expanded businesses. Phase 1 (business case development) future/recent developments (328,000 Increased economic activity and Future grant funding from LEP will be sq m safeguarded, 76,000 sq m output in ASEA. used for the following activities: unlocked) Unlocking/safeguarding economic m ss development at future/recent
development sites
17 km of new or enhanced flood Statutory flood defence and defence infrastructure. environmental requirements are met Wetland habitat at Hallen Marsh and ensuring planning compliance for Specialist ongoing consultant support Northwick measuring at least 85 ha in future development and allowing full Providing a strategic flood defence for detailed design and other works total. development potential of ASEA to be i solution and ecological mitigation and construction contractors. realised.
Reduced risk of flooding for Reduced frequency and severity of commercial properties, covering flood events, leading to reduced 575,000 sq m. business closures (temporary and ‐ permanent). .
Safeguarding existing economic .
activity and settlements
c .
Doc v21 Last updated Nov 2017
Doc v21 Last updated Nov 2017 3. Evaluation design and methodologies The key evaluation questions will include: Have the objectives and targets been met? Have the economic impacts (e.g. safeguarded jobs, GVA) materialised at existing commercial properties? Has the scale economic impacts safeguarded/unlocked/accelerated (e.g. net jobs, GVA, business rate growth) materialised at ASEA’s recent and future development sites? Do the assets meet planning and environmental requirements (i.e. at least 0.5% SoP flood defence levels to 2076 and at least 85 ha of wetland habitat creation)? Was the project delivered to agreed timescales and budget?
Evaluation will follow both the process and outcome/impact evaluation approach. Process evaluation will relate to establishing whether the project was delivered to timescales and budget. The process evaluation methodology will focus on comparing actual to expected expenditure over time based on contract details, receipts and invoices. This will take the form of a quarterly and annual review. Actual and expected timescales will be compared against the milestones outlined under Section 1 ‘Scheme Background and Context’. Timescale monitoring will be an ongoing process.
The outcome/impact evaluation process will involve monitoring of planning approvals, floorspace, job creation and GVA data over time. This will help to establish whether existing economic activity was protected and new economic activity was attracted as a result of the scheme. Attribution of the new economic activity to the project will be assessed by reviewing what development within ASEA proceeds outside of the consented 1957/58 planning envelope, as such development is heavily constrained in the absence of the project. Systematic review will take place 1,3 and 10 years following project completion to provide short and medium‐ to‐long term perspectives on the realisation of outcomes and impacts. Further, targeted interviews will take place with industry leaders, key business stakeholders/occupiers, landowners, developers, property agents and local officers responsible for economic development at ASEA (i.e. SGC/BCC economic development project managers). These interviews and discussions will help determine the extent to which the project is responsible for realising economic outputs and outcomes at ASEA; for example, targeted questioning will be used to ascertain whether business relocation/growth and business’ continued operation can be attributed to the project. This will aid with identifying whether the project generated the impacts that have been estimated in this FBC.
The evaluation process will be designed to assure the LEP that grant funding of around £66 million represented value for money, as well as an efficient and effective use of public funds. LEPs are particularly interested in how their investments support economic development, therefore the outcome/impact evaluation will focus on how key economic development indicators (e.g. jobs/GVA) will be safeguarded or enabled as a result of the scheme.
The scheme beneficiaries, including business and firms locating in ASEA, will be easily identifiable and accessible through stakeholder engagement processes and business surveys.
4. Data requirements 4.1 For schemes fully or part‐funded via the Local Growth Fund only Relevant performance indicators will be provided for each scheme when a draft logic model is shared at, or prior to, submission of a Full Business Case for approval. n/a
Doc v21 Last updated Nov 2017 4.2 Data collection methods Provide an overview of the data collection approaches including timing and frequency of data collection. Data collection for process evaluation will utilise data collected by the project team (e.g. actual versus expected expenditure profile, milestone completion). Budget monitoring and evaluation could take place on a quarterly or annual basis. Timescale monitoring and evaluation could take place on an ongoing basis (as/when milestones are reached).
Data collection for output/impact evaluation will utilise small‐area job and GVA data that is publicly available from ONS (e.g. the Business Register and Employment Survey, Sub‐Regional Productivity, Inter‐Departmental Business Register). This could be supplemented by business surveys of ASEA occupiers. Such surveys could qualitatively inform the actual level of net additional impacts, by asking for feedback on the importance of the project on business’ locational choices. Further, targeted interviews and stakeholder discussions will also take place with industry leaders, key business stakeholders/occupiers, landowners, developers, property agents and local officers responsible for economic development at ASEA (i.e. SGC/BCC economic development project managers). This will inform the evaluation process by trying to highlight attributable impact of the project. The review and analysis could take place 1, 3 and 10 years following project delivery.
Doc v21 Last updated Nov 2017 4.3 Data collection and establishing the baseline Refer to the scheme logic model to help structure the baseline data collection and reporting activities.
Metric Unit Frequency Data source Baseline Reporting to? (inc. Target) (& Responsibility) date Inputs Future £, by Quarterly Supplier invoices; FBC at full Highlight n source or Annual Quarterly grant claims – approval report; Finance Officer Project governance Outputs New‐build B2/B8 m2 Annual or Detailed design plans FBC at full Project floorspace – 404,000 sq Every two submitted to local approval governance, m net additional years, until planning authority evaluation the end of report every the City two years Deal (2038) New wetland habitat – Ha Annual or Detailed design plans – FBC at full Project minimum of 85 ha in Every two Main flood approval governance, total years defence/environmental/ evaluation New/Enhanced flood km landscaping contractor report after 1, defence – 17 km 3, 10 years Existing floorspace m2 Annual or Consultant team FBC at full Project protected to 0.5% SoP – Every two approval governance, 575,000 sq m years evaluation report after 1, 3, 10 years Outcomes and impacts construction stage # FTEs Annual Direct FTE numbers Throughout Highlight jobs from contractor. construction report; Indirect FTE numbers stage Annually calculated using Impact throughout Guidance Note by construction Project Manager. stage.
in construction £ Annual Contractor Throughout Highlight stage GVA expenditure/turnover construction report; profile, with project stage Annually manager applying throughout benchmarks and ratios construction from Impact Guidance stage. Note to establish direct and indirect impact.
0 net additional jobs # FTEs Annual or Business surveys and/or FBC at full Project Every two ONS; plus targeted approval governance, years interviews/discussion evaluation with relevant report after 1, stakeholders. 3, 10 years n net £, GVA Annual or Business surveys and/or FBC at full Project additional GVA Every two ONS; plus targeted approval governance, years interviews/discussion evaluation with relevant report after 1, stakeholders. 3, 10 years net £, Annual or SGC and BCC finance FBC at full Project additional business rates business Every two department, LEP’s approval governance, rates years Growth Incentive evaluation Doc v21 Last updated Nov 2017 report after 1, 3, 10 years 1 safeguarded jobs # FTEs Annual or Business surveys and/or FBC at full Project Every two ONS; plus targeted approval governance, 5. Delivery plan
This project will be subject the WECA performance management system and evaluation framework. This will include a post implementation review (PIR) and post project evaluation review (PER), which will include a lessons learned workshop to capture and disseminate key learning points, in accordance with best practice. Each evaluation will consider team performance, benefits realisation assessment, better information management, asset performance evaluation, and environmental and other long‐term monitoring.
Data collection for the budgetary element of process evaluation will occur on a quarterly basis, reviewing financial records to determine patterns of expenditure on an ongoing basis throughout the construction stage. The findings of the evaluation will be reported on a quarterly basis through a highlights report prepared by the project manager for the LEP. The timescales element of process evaluation will occur on a continual basis, with particular focus around the time of specific milestones.
More specifically, data collection with regard to outputs will rely on planning application and approval data for permitted and completed development sites alongside reports from the main contractors for project works. The EA will need to confirm the quantum of existing development protected by the flood defence scheme as the project progresses, using flood modelling. This information will be reported in Years 1, 3 and 10 post‐ completion. Baseline data will be recorded at the point the LEP full business case is approved, as development may begin to come forward in advance of completion of the project, based on confidence that the project will be delivered in light of LEP approval. At this stage, it should be noted that 20,000 jobs currently exist in the wider ASEA area (Business Register and Employment Survey, 2016). This figure can act as the baseline value against which future growth and impact evaluation can be measured.
Data relating to outcomes and impacts will be collected from the point of LEP approval also, for similar reasons. Data will be sourced for small area geographies from publicly available datasets where possible (e.g. BRES, IDBR, ONS). This data will be supplemented by data from business survey data and targeted interviews with key stakeholders (including businesses, developers, landowners, property agents and local authority officers). As above, operational stage impacts will be reported after 1, 3 and 10 years following project completion. Construction stage impacts will feature within the project highlights report, on an annual basis.
Doc v21 Last updated Nov 2017 6. Resourcing and Governance
A monitoring and evaluation budget of 0 will be allocated as part of the ongoing project management costs for the project. Project management costs are covered through the LEP grant funding; therefore, the monitoring and evaluation budget will be covered by LEP funding. The budget will cover baseline data collection, development of quarterly highlight reports during the construction stage and the biennial evaluation report. The biennial evaluation report may involve some consultant support.
Risk management and quality checking will be the responsibility of the project manager. Such issues will be minimised by use of SGC’s professional services framework to source consultant support.
In the spirit of collaboration on this project, EA processes for evaluation and monitoring will be adopted where appropriate and considered best practice. Similarly, the evaluation process will benefit from drawing on the experience of multiple project partners, including BCC and SGC.
1
Doc v21 Last updated Nov 2017 7. Dissemination The evaluation will be used to determine whether the project represented value for money as well as efficient and effective use of public resources. The process evaluation will highlight whether the project was delivered to time and budget. The process evaluation will be designed to inform the project partners on project progress and financial position. This could provide insight into possible budget efficiencies and process enhancements that could be applied on future major projects, including on collaborative schemes.
The outcome and impact evaluation will be used to determine the economic development effects of implementing the project. This will inform SGC and BCC, and specifically the planning and economic development officers in both organisations, on the scale of development that materialises at ASEA as well as the number of jobs and level of economic activity (measured in terms of GVA) unlocked by the scheme.
Findings from the process evaluation will be presented in quarterly highlight reports for internal use amongst the project partners to inform future programme and project management. Where lessons learned can be applied elsewhere, the highlight reports may be disseminated to a wider public‐sector audience. Biennial evaluation reports will be disseminated more widely, including publication on the websites of the project partners. This will allow the public to access information relating to the economic development impacts of the scheme more easily. Again, any lessons learned through the evaluation reports can be shared between the project partners, as well as more widely across the West of England and further afield if appropriate.
Doc v21 Last updated Nov 2017 Appendix A
ASEA – Build-up of Flood Defence Levels The below information has been produced to help the ASEA EMFD Project Delivery Board (PDB) and the ASEA Strategic Directors Board (SDB) understand what will be delivered on site with regards to Flood Defence protection. It describes how the team have met the instruction from the SDB to “go as high as possible within the rules of planning and affordability”. CH2M have worked hard with regards to the LEP business case to ensure that not only are the levels justifiable but also that we get the best and highest protection scheme that we can. This document should be read in conjunction with the Technical Memorandum produced by CH2M “2076 v 2116 Tidal Flood Defence Levels” (see Appendix B). The conclusion of that document is that there is neither a planning justification nor a LEP business case justification for the 2116 scheme, and that submission to planning of a full 2116 scheme would be a significant planning risk and therefore a risk to project delivery. However, this document then looks in detail at the substantial defence height that can be achieved whilst remaining within the acceptable limits of planning and business case justification. There are numerous different factors that must be considered when deciding on a Flood Defence level: Sea Level Rise predictions, settlement, risk allowance, dual probability of events (I.e. sea level, wave action, wind, tide etc). These are all complex to deal with and often change due to new information from research. To ensure protection, “worst case” scenarios are often used. Furthermore, the coastal conditions vary along the coastline, meaning that there is not a single uniform flood defence level that should be applied throughout. The final design standard of protection from an engineering perspective (when considering all of the above) is referred to as a 2076 level of protection, however, in reality it is a 2076 “plus” solution and would, based on current predictions also protect against a 2116 event in most locations. The below table sets out where additional allowances have been made over and above usual assumptions for each factor that makes up a flood defence level.
Additional Level or Depth Allowances (m)
Description Walls Embankments
Initial Design Still Water Flood Level (From EA Coastal - 1.18m Boundary Data, established from long-term level gauge records) and allowance for wave action (varies, depending on foreshore run-up, shape of flood defences, and exposure of coastline)
Hydraulic Uncertainty (an assessment of the statistical error 0.25 0.25 that may exist in the coastal boundary data and wave run-up calculations)
Initial settlement during construction period 0.05 0.15
Settlement over 60 year design life (for a 3.0m high 0.05 0.25 embankment) Additional Level or Depth Allowances (m)
Description Walls Embankments
Desiccation allowance (maximum allowance from EA N/A 0.0 guidance for a high-risk material is 0.9m). However, the existing flood defence banks do not show signs of desiccation, so this is thought to be very cautious. To reduce height of designed embankments, we will allow for soil blending and admixtures within the upper layers to reduce risk of desiccation cracking.
Topsoil (considered as not waterproof) above flood defence 0.0 0.20 level
Maximum total allowances above still water flood level 0.99 2.67
The below graph shows the total level increases provided within the design to provide the required flood defences. These levels includes the allowances as set out in the above table. The below level increases are then added to the basic still-water design flood levels to create actual levels above AOD.
1:200 AEP (2116)
1:200 AEP (2076)
One final aspect to note, is that the project team are still looking into the possibility of FDGiA funding to “top-up” the above levels where technically and financially possible. For example, there is a wall to the northern end of the project, that is not required to protect the ASEA but would protect some existing properties. Furthermore, where walls are required, increasing heights are not always very expensive. For example the walls in the port could potentially be increased now rather than later, and this is likely to suit the port better. This same approach cannot be applied to the embankments north of Severn beach or the Severn beach wall itself (Binn Wall) as raising a wave return wall or introducing rock armour to ensure robustness of embankments is not financially viable or environmentally justifiable at this stage. The above information sets out the requirements for the ASEA flood defence project. The levels derived for the scheme are justifiable and also ensure the maximum standard of protection is realised. This approach meets the requirements of the Strategic Directors Board and it is recommended that the Project Delivery Board accept this approach to enable the project to move forward.
Appendix B
T E C H N I C A L MEMORANDUM 2076 v 2116 Tidal Flood Defence Levels
PREPARED FOR: Manor Singh
COPY TO: ASEA Project Delivery Board
PREPARED BY: Gary Wilson, Bruce Slattery, Chris Green, Karn Shah
DATE: May 15, 2017
PROJECT NUMBER: 675037
APPROVED BY: Luke Lovell and Naomi Gornall (EA client PM)
About this note This note responds to an e-mail from Ian Steel (South Gloucestershire Council), date 28th April 2017. The e-mail was sent following the April Project Delivery Board Meeting on the 27th April 2017. During that meeting, a high level summary of the ‘LEP’ and FDGiA economic cases were presented, following a more detailed presentation of the same cases on Monday 24th April (which Ian Steel did not attend). In the e-mail, Ian asks CH2M to consider some observations and these are addressed as follows. Response to Questions Q1. The presentation seems to set-out to make the case for the 2076 period. This wasn’t the ask of the Strategic Directors Board (SDB). The ask was to develop the 2116 option and then only to revert to the 2076 if there was “kickback” through the business case development process.
Following the SDB CH2M were instructed to “go as high as possible whilst remaining within any planning or business case justifications”. This is what the project team have now achieved.
Providing a 1 in 200 year standard of protection in 2116 was developed as an option, but the appraisal has found it cannot be justified, either for planning purposes, or economically (in terms of LEP objectives).
The key justification for the scheme is the regeneration of the ASEA. The scheme is limited to providing an equivalent measure to that which would be imposed on the developers if they were to currently seek planning approval. In the case of tidal and other flood defences, the developer would have to land raise or provide other defences to meet the 60 year period at the time of application. As the City Deal lasts for a further 21 years (to 2038), and given the defences have been designed to the higher tidal range with additional free board and over topping allowances, they provide a level of defence that would be suitable for the applications received in 2038. Additionally, From a LEP Business Case point of view, there are only marginal additional benefits from building to 2116 standards, despite a significantly higher cost.
Q2.The employment ratio used in relation to construction costs could probably justify a higher employment multiplier figure i.e. from 1.7 to 1.8. This would also create an alignment so that the employment and output multipliers derive from the same construction sector. This may not have a significant impact upon benefits during the construction phase though.
1 2076 V 2116 TIDAL FLOOD DEFENCE LEVELS
The LEP Guidance provides a range of factors for employment multipliers (1.7 to 2.0) and output multipliers (1.8 to 1.9), and suggests that “Generally, lower multipliers would be used for flood defences or public realm works”, hence why the bottom end of the ranges was selected for both calculations. As noted, any change in multiplier factors will have limited impact on the project overall, as such we do not propose to change the factors for the scheme.
Q3. Is it a correct approach to compare the BCR between the two periods i.e. 2076 vs 2116? It’s reasonable to assume that all of the planned development is likely to take place in say, the next 15(ish) years with the ‘benefit’ realised by say, 2030 – 2040. Anything after this period is likely to be a redevelopment of an existing site. Therefore, it’s hardly surprising that the 2116 scenario returns a low BCR when compared to 2076. Indeed, any comparison between a 2030/40 date and any date after this period is likely to return a very limited benefit.
The analysis follows the development forecast specified in the Amion model. Therefore all of the planned development is likely to take place in the next 21 years to 2038 (i.e. the duration of the City Deal/business rate retention). The benefits have a persistence of ten years, as per the Amion model, although impacts are only captured up to 2038. The rationale for a 2076 scheme design is for planning reasons. The scale of impacts (in terms of future development land), generated by 2076 and 2116 levels of protection are identical, the only factor affecting BCRs is the increased cost of implementing 2116 levels of protection. This leads us to maintain that this is both a correct and proportionate approach for the comparison of the alternatives for the scheme.
Q4. (Linked to the above point) should there be a greater consideration/weight to value for money? Costs will naturally be higher for the increased 2116 level of defence. However, the actual additional cost for the forty years to 2116 are effectively 50% of the yearly construction costs to 2076. Should this not be a factor in the value for money argument?
We don’t consider this point to be relevant, as the objective of the project is to promote planning applications and thus regeneration of the area. As Ian points out, the site will be developed by 2076, hence any marginal effects after this time are not relevant to us in terms of the project.
Q5. It may be inappropriate to draw the comparison to the scale of business rate uplift. The application is through the LEP ‘One Front Door’ process. Therefore, while we have an indicative Outline Business Case aligned to the use of City Deal, the LEP application at Full Business Case stage will be allocated to the appropriate funding streams available to the LEP i.e. not just the business rate uplift calculations through City Deal.
SGC have been consistent in their advice to date that LEP funding towards the scheme would be repaid via business rate uplift as part of the pooled Economic Development Fund. Therefore we have tested whether the scale of business rate uplift is sufficient to cover the cost of the scheme. If there is no onus or less onus on relying on business rate uplift to repay LEP funding, then we can focus less on the importance of generating business rate uplift.
It should also be noted that if the project will utilise multiple funding streams as part of the LEP ‘One Front Door’ process, we require clear steer on what funding streams will be accessed as well as timing and scale of funding to be secured from each potential stream. Further, we will need advice on the nature of the funding (i.e. funding via grant, interest-free loan, interest-based loan). Depending on the final funding package, there is a risk of further costs and delay to the programme, resulting from additional work to rectify the potentially abortive work based on information to date.
2 2076 V 2116 TIDAL FLOOD DEFENCE LEVELS
Q6: Accepting the point above: a) The figures as tabled, include a maximum optimum bias at 60%. This seems to be excessive. Being brutally honest, it does start to suggest that CH2M and the Early Supplier contract are not providing reasonable construction sums at the outset in lieu of a high optimum bias.
We believe that the 60% optimism bias at this stage can be justified, given the significant risks related to ground conditions, archaeology, working adjacent to a European Protected habitat site and Network Rail assets, etc. Given the benefits justify this, we recommend erring on the side of caution at this stage, but are planning to critically review the optimism bias during a risk workshop planned on the 15th May.
This is also usual practice at this stage within large scale Environment Agency (EA) projects with the types of risks we have identified. We have checked and the EA project team and they are comfortable with this figure at this stage. We hope to reduce the optimism bias allowance before business cases are finalised but we will need to invest in more detailed investigations pre-FBC before we can confidently reduce the allowance. b) If looking at parcels that are able to help fund the 2076 and 2116 flood defence interventions (and indeed ecology interventions as well) through business rate uplift (as part of City Deal) then we shouldn’t just be looking at the parcels directly identified through the Amion and Atkins work but, the entirety of the fiscal boundary of the Enterprise Area.
The current analysis focusses on those plots that are additional as a result of the scheme, i.e. they lie outside the 57/58 boundary and within the fiscal boundary, but would only come forward in the event of the scheme being implemented. We do not capture business rates from existing development or development inside the 57/58 boundary that could theoretically come forward in the absence of the scheme. This means the assessment captures only the additional impacts of the scheme, as per LEP Guidance.
Q7. The 2116 scenario assumes the costs for lock gates. Is it reasonable to assume that a) the project would pay for such costs and b) that they will actually be a requirement given the aspirations at Bristol Port for the deep water terminal in the estuary.
Whilst the lock gates would be a requirement if we were able to justify the 2116 scenario (as they would be required to provide protection to the wider ASEA area), because the development is enabled in its entirety by 2076, there is no economic case for funding the dock gates now. Indeed the mechanical lock gates installed now would be worn out long before 2076. It would be entirely speculative to anticipate whether or not the deep water port will be developed during the life of the scheme.
Q8. At an earlier meeting we had previously talked in terms of the business case development being an iterative process. I would suggest that the process incorporates the Economic Development Teams and the two Councils in much the same way as the development of the other technical disciplines e.g. flood specialists for flood/flow modelling, ecology specialists for survey requirements etc.
In addition to meetings with SGC’s project lead in the early and middle stages of the project to date, we are keen to attend more regular meetings with relevant officers at both councils as the project develops.
[ 3 2076 V 2116 TIDAL FLOOD DEFENCE LEVELS Conclusions To conclude, we believe that there is neither a planning justification nor a LEP business case justification for the 2116 scheme, and hence a 2076 scheme level should be selected as the core preferred option for this project. A full 2116 scheme would be a significant planning risk and therefore a risk to project delivery. Further work in now being undertaken with regards to the 2076 scenario and a further document has been produced “ASEA – Build-up of Flood Defence Levels” that looks in detail at the substantial defence height that can be achieved whilst remaining within the acceptable limits of planning and business case justification.
4 Appendix C
Avonmouth Severnside Enterprise Area
Draft High Level Options Report
Prepared for Environment Agency
1 September 2016
CH2M HILL Ash House Falcon Road Exeter EX2 7LB
Contents
1 Introduction ...... 7 1.1 Background ...... 7 1.2 Study area and boundaries ...... 9 1.3 Previous analysis ...... 10 1.4 Project objectives...... 13 1.5 Purpose of this report ...... 14 2 Appraisal Process ...... 15 2.1 Appraisal process ...... 15 2.2 Stakeholder consultation ...... 15 3 Area 1 – Severnside ...... 16 3.1 Issues, Risks, Constraints and Opportunities ...... 17 3.2 Defence alignment options ...... 18 3.2.1 Coastal Defence – Existing alignment ...... 19 3.2.2 Set Back Defence 1 – Realigned close to M4 ...... 20 3.2.3 Set Back Defence 2 – Realigned close to A403 ...... 20 3.3 Stakeholder comments ...... 21 4 Area 2 – Avonmouth Docks ...... 22 4.1 Issues, Risks, Constraints, and Opportunities ...... 23 4.2 Defence alignment options ...... 24 4.2.1 Coastal Defence – Existing alignment ...... 25 4.2.2 Set Back Defence 1 – Realigned behind Avonmouth docks ...... 26 4.2.3 Set Back Defence 2 – Realigned through Avonmouth ...... 26 4.3 Stakeholder comments ...... 27 5 Area 3 – Central Embankment and Outfalls ...... 28 5.1 Issues, Risks, Constraints and Opportunities ...... 29 5.2 Defence alignment options ...... 30 5.2.1 Coastal Defence – Existing alignment ...... 31 5.2.2 Set Back Defence 1 – Realignment behind the railway ...... 32 5.2.3 Set Back Defence 2 – Realignment adjacent to A403 ...... 33 5.2.4 Surface drainage (Rhine network and outfalls) ...... 33 5.3 Stakeholder comments ...... 35 6 Area 4 – Hallen Marsh ...... 36 6.1 Habitat creation requirement ...... 36 6.2 Habitat creation process ...... 38 6.3 Issues, Risks, Constraints and Opportunities ...... 38 6.4 Water level management ...... 40 6.5 Stakeholder comments ...... 40 7 Area 5 – Northwick ...... 42 7.1 Habitat creation requirements ...... 42 7.2 Habitat creation process ...... 44 7.3 Issues, Risks, Constraints and Opportunities ...... 44 7.4 Water level management ...... 46 7.5 Stakeholder comments ...... 46 8 Option Assessment ...... 48 8.1 Assessment criteria ...... 48 8.2 Recommended option alignments ...... 51 8.2.1 Area 1 ...... 51
8.2.2 Area 2 ...... 52 8.2.3 Area 3 ...... 53 8.2.4 Area 4 ...... 55 8.2.5 Area 5 ...... 55 9 References ...... 56
Appendix A – Long-list assessment matrix Appendix B – Hallen Marsh Option Sketches Appendix C – Northwick Option Sketches
Document History
Reference Number: IMSW002194-CH2-Z00-000-RP-C-0001 Client Name: Environment Agency This document has been issued and amended as follows:
Version Date Description Created By Verified By Approved By
1 04/08/2016 Draft Ian Ball Chris Green Chris Green
2 01/09/2016 2nd Draft Ian Ball Chris Green Luke Lovell
1 Introduction 1.1 Background The Avonmouth / Severnside Enterprise Area (ASEA) is a development project designed to enable continued economic growth in Bristol and South Gloucester. It occupies an area of low lying land to the northwest of Bristol, adjacent to the Severn Estuary between the mouth of the River Avon and Aust cliffs (Figure 1). The area contains a number of settlements, including Avonmouth and Severn Beach; infrastructure for a wide range of existing and new industries; and an extensive area of undeveloped land to the east of Chittening and Severn Beach that is intended for further industrial and commercial development.
Figure 1 Geographic location of the Avonmouth Severnside Enterprise Area project location – highlighted in red (Crown copyright and database rights 2016 Ordnance Survey).
Existing industrial installations within the area include: • Bristol Port and its associated facilities; • Seabank Power Station; • Wind turbines; • Liquid Natural Gas (LNG) Plant; • Underground gas and oil pipelines; 7
• Sewage Treatment Works; and • Waste treatment plants. These facilities are supported by part of the national highway network; passenger and freight railway lines; and overhead power lines. While some significant development has taken place within the ASEA, the extensive area of undeveloped land offers significant opportunities for the local economy to grow and increase employment for the region. In 1957 and 1958 planning permission was granted for approximately 750 hectares of land and an additional 450 hectares extending into the Severn Estuary. The initial permissions were granted for the development of a chemical works facility; however, the permissions provide “in principle” consents for a wide range of land uses which have been successfully implemented to provide the following: • Factories for the production of chemical and allied products; • Offices; • Warehouses and stores; • Canteens, clubs, hostels, training establishments, amenity and welfare buildings; • Sports pavilion and sports playing fields; and • Infrastructure to support development of the above. Further development will ensure that the area expands its role as an internationally significant industrial location, able to attract business investment and provide increased employment for the local and wider population. While the area is currently protected from flooding by formal and informal flood defences as well as surface water drainage infrastructure, the ongoing development of the ASEA is dependent on the improvement of flood defences along the Severn estuary and effective drainage of surface water from the development area. The influence of climate change and its effect on sea level rise and rainfall increases will reduce the standard of protection provided by flood defences over time, requiring additional works. Projections for sea level rise are varied, but suggest a potential increase in water level of 0.4-1.7m over the next 100 years (EA, 2011 and UKCP09, 2016). Such an increase poses a risk from flooding both from elevated tidal levels and additional wave overtopping, permitted by larger waves reaching the coast. The result of additional flood risk will be an increase in the existing flood inundation area, affecting other parts of the ASEA, with much of the area between the coast and the M49 flooded by a 1.3% AEP event in 2110. Such an increase in flood risk would affect over 3000 existing properties in the flood plain and will act as an obstruction to further economic development. A key planning requirement for allowing further development within the ASEA is the provision of mitigatory freshwater habitat, necessary to address the projected environmental impacts created by the proposed new industrial facilities that will be constructed in the coming years. The following key land-use constraints apply: • The need to avoid impacts on the internationally designated intertidal habitat in the Severn Estuary; • The proposed flood defences have potential to interfere with industry and transport links both in the Bristol Port and throughout the study area; • The project should avoid specification of active flood defences such as demountable barriers and flood gates; • Flood defences have potential to disrupt rail transport and the physical infrastructure of the railway. Special permissions will be required to undertake works on the railway and associated approvals processes can cause long delays;
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• The study area is likely to include culturally and historically significant water management structures and settlements, and pending completion of an archaeological desk study, this may constrain the footprint or alignment of some options; • Potential land contamination throughout the study area. The following key environmental constraints apply: • The study area is likely to include culturally and historically significant water management structures and settlements, and pending completion of an archaeological desk study, this may constrain the footprint or alignment of some options; • Sites identified for potential habitat creation projects are likely to contain Protected Species, and this may affect the feasibility of some habitat creation options; and • Some stakeholders are likely to object to raising water levels in the network of rhines that could be used to provide water supplies to the habitat, due to potential for increased flood risk. 1.2 Study area and boundaries The Avonmouth Severnside Enterprise Area is protected, to some degree, by flood defences along the River Avon and the Severn Estuary. These defences take many different forms, are in varying condition, and provide a variable standard of protection (see technical note IMSW002194-CH2-Z00- Z00-TN-C-0002 for further details of weak spots). The Enterprise Area itself is drained by a network of rhines that discharge surface drainage into the Severn Estuary through a series of outfalls through the flood defences along the Avonmouth to Aust shoreline. Modelling work to understand the capacities of the rhine network and outfalls is ongoing, but will provide important information regarding flood management The project also includes the creation of two areas of habitat mitigation. Creation of lowland wet grassland (freshwater) and open water (freshwater lakes, ponds and scrapes) habitats is necessary to address the likely impact of future development of the enterprise area on supporting habitats that lie outside the Severn estuary SPA and Ramsar site boundary, which have been identified by the Cresswell Report (Cresswell Associates, 2011), as supporting over-wintering and migratory wildfowl and wading birds (i.e. SPA qualifying species and qualifying assemblages). The Cresswell Report has identified that approximately 10ha of open water habitat and 75ha of wet grassland habitat is required. Figure 1 shows the study area and defines the five smaller areas used in this project for option development and implementation, as follows: • Area 1 – Severnside • Area 2 – Avonmouth Docks • Area 3 – Central Outfalls & Existing Embankments • Area 4 – Hallen Marsh (habitat mitigation area) • Area 5 – Northwick (habitat mitigation area)
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Area 1 - Severnside
Area 5 - Northwick
Area 3 - Central Outfalls & Existing Embankments
Area 2 – Avonmouth Docks
Area 4 – Hallen Marsh
Figure 2 – Coastal defence areas and habitat mitigation areas for the Avonmouth Severnside Enterprise Area (ASEA). 1.3 Previous analysis A range of documents have been produced which explore the possible strategic approaches for flood risk management in the ASEA, and which examine the technical requirements for flood defences. These documents cover high-level strategic approaches as well as more detailed examination of specific alignments with relative benefits and constraints. The Severn Estuary Shoreline Management Plan (SMP) (Severn Estuary Coastal Group, 2000) indicated a preference for ‘Hold the Line’ in the short and long term between Avonmouth and Aust, although it leaves open the option for managed realignment in the long-term.
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The draft Severn Estuary Shoreline Management Plan 2 (SMP2) updated these preferred policies, and stated that ‘Hold the Line’ was preferred in the short-, medium-, and long-term, accounting for sea levels rise. The Tidal Severn Flood Risk Management Strategy (TSS) (Environment Agency, 2006) advanced specific approaches that may be adopted within the project area. The strategy identified a range of 23 possible flood risk management options throughout the Severn Estuary, which was subsequently reduced to 17 options as a consequence of economic, technical and environmental analysis. The Severn Estuary was divided into a number of Management Units, for which a preferred option was identified during further analysis (Table 1). These options were in line with the preferred options described in the SMP2. Table 1 Summary of TSS strategic recommendations (extracted from Capita Symonds, 2011)
Management Unit Settlement Preferred Option 7/B East – Northwick Maintain current line of defence to existing Old Passage to New Passage standard of protection 15/A East Severn Beach Raise defence to optimum standard based in New Passage to New Pill current guidance 15/B East Severnside Works Maintain current line of defence to existing New Pill to Mitchell’s Salt Rhine standard of protection 15/C East Avonmouth Construct new line of defence Mitchell’s Salt Rhine to Customs House
The Severn Estuary Flood Risk Management Strategy (Environment Agency, 2011) provided an overview of the high level appraisal of flood risk for locations throughout the Severn Estuary. The economic appraisal within the strategy indicated that Present Value damages of £473.8 million under the ‘Do Nothing’ scenario for the ASEA (Flood Cell 7 in the strategy). The strategy indicated that the ASEA offers a high standard of protection at present (SoP of 0.5% AEP broadly, but with weaker sections with 5% AEP along the River Avon), but that it would decline by 2030 and would fail by 2060, providing no flood defence. As such it was concluded that the ‘Do Minimum’ option of maintaining structural integrity of existing defences within the Severn estuary was not appropriate because of the declining SoP. The Strategic Flood Risk Assessment for Avonmouth and Severnside (SFRA2) (Bristol City Council, South Gloucester Council and Lower Severn Drainage Board, 2011) provided a more detailed examination of the study area and included an asset survey of the Avonmouth and Severnside flood defence as well as Flood Zone Maps for the area. This data was used to formulate Local Coastal Defence Policies for 15 discrete sections of the coast between Avonmouth and Aust. ‘Hold the Line’ was the only option recommended for the majority of the sections, with ‘Retreat’ considered for the former ICI waste disposal site south of Severn Beach, and ‘Advance’ of the defence line along sections where the railway is presently the de facto flood defence. The SFRA2 provided broad order cost estimates for defence height raising on existing alignments indicating costs of £56.8 million in 2010 prices to raise defences to 10.74mAOD to account for climate change, however the report indicates that this cost excludes pump systems and storage necessary for addressing issues when the rhine system will not effectively drain, as well as maintenance costs. The SFRA2 suggested that the indicative cost for raising banks and providing other infrastructure as well as maintenance would be between £200-300 million, and was unlikely to be acceptable on environmental grounds. The report concluded by highlighting the need for reassessment of the target crest level for flood defences, investigation of the feasibility of defences at the railway line, and further work in cost estimation. The Avonmouth and Severnside Integrated Development, Infrastructure and Flood Risk Management Study (Bristol City Council and South Gloucestershire Council, 2012) examined the 11 potential issues for new development within the ASEA covering a wide range of criteria. Topics covered included planning policy, contaminated land, heritage, ecology, transport links, and flood risk. The study confirmed that the existing defences provide varying Standard of Protection, with many areas falling below that required by the Environment Agency for new development. The study indicated that sea level rise over a 100-year period may be as much as 1m, leading to significant overtopping and flood risk to the majority of the ASEA. The principal flood risk mitigation options identified by Bristol City Council and South Gloucestershire Council (2012) included: 1. Do nothing – this option was considered unacceptable due to insufficient standard of protection. 2. Implementation of strategic land raising across the study area on a site by site basis to ensure that development is above the predicted flood levels - this option was considered unacceptable as it would result in elevated flood risk to third party areas, contrary to government policy. 3. Implementation of a strategic flood defence by raising existing defences to a height of 10.74m OD – this option was the recommended approach, although it was recognised that residual risk from wave overtopping, larger tidal flood levels, breach, and fluvial flooding will still exist. The study underlined the need for a more detailed assessment of residual risk associated with wave overtopping after improvement works are completed. In parallel with the Avonmouth and Severnside Integrated Development Infrastructure and Flood Risk Management Study, was the development of the outline development strategy (AMION Consulting Limited, 2012), which picked up on the previous work for the strategic flood defences necessary to support the development of the ASEA. An options appraisal was completed which examined two alternatives for provision of flood defence, with new structures providing a consistent crest level of 10.74m OD and new structures providing a consistent crest level of 12.74m OD. The assessment examined the cost of such works as well as the potential environmental impacts of flood defence works. Preference was identified for the lower crest level due to the lower cost and the reduced environmental impact for this approach, however the strategy acknowledges that residual risk of flooding would remain. It was indicated that additional measures to mitigate the residual risk would need to be incorporated into the final scheme. The Avonmouth-Severnside Flood Management Optioneering report (Atkins, 2013) examined the following three broad solutions to addressing increased flood risk, but also considered further detail in how each of the broad solutions might be achieved through engineering works etc. 1. Strategic ground raising. Due to the extent of ground raising or embankment height required (up to 4m), ground raising was deemed more resilient to flooding; 2. Improve existing tidal defences, with localised fluvial flood protection. Sub-variations within this option include; and 3. Secondary perimeter road raising (A4-A403 defences), with localised fluvial flood protection. Sub-variations within this option include. Assessing the various potential engineering options against engineering, economic and environmental parameters, resulted recommendation of phased works with: • Construction of the landward perimeter wall, or seaward revetments and embankments, along Avonmouth Docks during 2012-2016. This will address the source of greatest tidal flood risk, particularly to the general Avonmouth development area and Avonmouth village. Non-structural measures may be adopted to address fluvial flood risks. • Wave recurve wall addition to the Aust to New Passage earth embankment if required during 2017-2030. This will address the source of tidal flood risk, particularly to the 12
Severnside development area and the communities of Northwick, Redwick and Pilning. Residual ring banks or ground raising for development sites at unacceptable fluvial flood risk, with flood storage and environmental mitigation adopted. Re-engineering of the railway embankment along Chittening Warth may also be completed. The report concludes with discussion regarding the additional work that is required to confirm the choice of a preferred option for flood defence, including development of the business case; further site investigation to confirm the conditions and inform design; engineering design; and environmental assessment. 1.4 Project objectives The overall strategic objectives of the project were identified at the outset as: 1. To ensure that the identified solutions for the flood defences and ecological mitigation in the Avonmouth-Severnside area are adequate for the proposed economic development, to support business growth as outlined in the Enterprise Area Outline Development Strategy. 2. To ensure delivery of the flood defence and ecology mitigation elements through securing the funding required. This means gaining approval from the West of England Local Enterprise Partnership (LEP) for the Full Business Cases for Flood Defence and Ecology Mitigation. 3. To maximise the opportunity for FDGiA through the OBC and FBC processes by reducing flood risk to existing domestic and industrial properties within the Avonmouth-Severnside flood cell. The objectives of the project were refined and expanded during discussions with Environment Agency and key stakeholders, and have been established to direct the development of a sustainable scheme that meets the statutory responsibilities of all parties while aligning with individual organisation policies. The project objectives are outlined below and have been separated into four broad categories: Economic objectives • Reduce the cost of flood damage; • Reduce the risk of flooding to infrastructure, utilities and businesses; • Enable delivery of the Outline Development Strategy; and • Ensure the scheme is affordable/meets funding criteria. Social objectives • Reduce the risk of flooding to properties and life; • Improve landscape; and • Improve recreational opportunities. Environment objectives • Improve ecological opportunities; and • Minimise environmental impact of works. Technical objectives • Take account of risks of climate change; • Delivers best practice; • Ensure the scheme is deliverable (in engineering terms); 13
• Ensure the scheme is capable of achieving required consents; and • Minimise disruption to infrastructure and services during construction. 1.5 Purpose of this report This report provides a summary of the appraisal process for the improvement of flood and coastal erosion risk management (FCERM) structures along the estuary frontages of the Avonmouth Severnside Enterprise Area, as well as the options for habitat mitigation further inland. The FCERM options primarily consist of elevated structures to prevent overtopping and inundation during tidal events, as well as flood conveyance channels and storage areas to manage surface drainage issues. The purpose of this report is to provide a summary of the long-list appraisal process, highlighting the assessment criteria used within the appraisal process, and to discuss the outcome of the long-list option appraisal. The report concludes by indicating how the appraisal process will be advanced during subsequent stages of work. The report includes the following sections: 1. Introduction – presents the background of why the project work is being undertaken and summarises the previous analysis completed to date; 2. Options Assessment – Describes the appraisal process, and details the stakeholder consultation conducted during the option assessment; 3. Area 1 – a summary of the defence alignment options considered for Area 1; 4. Area 2 – a summary of the defence alignment options considered for Area 2; 5. Area 3 – a summary of the defence alignment options considered for Area 3; 6. Area 4 – a summary of the options in creating mitigating habitat within Area 4; 7. Area 5 – a summary of the options in creating mitigating habitat within Area 5; and 8. Option assessment – proposes an assessment process for the appraisal of short-list technical options and highlights the data required to complete the appraisal. The full Options Assessment Summary Table is included as Appendix A.
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2 Appraisal Process 2.1 Appraisal process The adoption of the two-phase Options Appraisal process will enable a progressive approach for determining a preferred option for each area. The initial phase will discuss the high level options and help to identify the most suitable alignment for flood defences and habitat mitigation, considering likely environmental impacts, buildability, health and safety concerns, and whole life cost implications. The subsequent phase of analysis will focus on the specific management techniques to be employed at each alignment, focussing the option appraisal process. 2.2 Stakeholder consultation A stakeholder consultation event was held at Bristol on 14th June 2016 to present the long list options for different defence alignments throughout the study area and to seek comments on the direction of options development. Stakeholders attending the event comprised representatives from: • Bristol City Council • Highways England • South Gloucestershire Council • Network Rail • Environment Agency • Wessex Water • Natural England • Lower Severn Internal Drainage Board • West of England LEP • Bristol Port
Specific topics covered during the workshop included discussion of the alignment and technical options under consideration for the flood defence works, and discussion about the various ways in which wet grassland and open water habitat can be created to provide the necessary habitat mitigation required for the qualifying species and assemblages of birds associated with the Severn Estuary SPA/Ramsar site. The event sought to identify priorities and preferences in achieving the project objectives, which the project team subsequently used in the formulation of this report and will use in further appraisal work moving forward.
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3 Area 1 – Severnside Area 1 comprises the existing hard defences at Severn Beach and approximately 4km of the estuary frontage embankment between Severn Beach and Aust. The Area 1 frontage connects to an area of high ground at Aust Cliffs to the north, however the entire length of Area 1 is characterised by low lying ground (Figure 3).
Elevation (mOD)
Figure 3 – Area 1 flood defence extent between Severn Beach and Aust. This map is reproduced from Ordnance Survey © material by Halcrow on behalf of the ENVIRONMENT AGENCY with the permission of the Controller of Her Majesty’s Stationery Office. © Crown copyright. Unauthorised reproduction infringes Crown copyright and may lead to prosecution or civil proceedings. Licence Number: 100026380
At the southern end of Area 1 the land behind the defences is used for residential development in the form of communities at Severn Beach and New Passage. Further north, the land is predominantly used for agriculture, with some residential property scattered amongst the villages of Northwick and Pilning, and a number of small hamlets. The southern portion of Area 1 includes the eastern pier of the second Severn crossing and connects to the settlement of Severn Beach. Severn Beach includes a large number of residential properties as well as retail facilities and infrastructure supporting the settlement. The flood defences throughout Area 1 varies as the level of development behind the defence changes. Details of the flood defence assets within Area 1 are presented in Table 2, including a description of the defence, the owner responsible for the maintenance of the asset, the condition (estimated from visual inspection) and the estimated residual life extracted from the coastal defence technical note (CH2M, 2016).
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Table 2 Area 1 flood defence assets
AIMS ref. Description Operator Condition Residual life (yrs) 112GF22200301C03 - Steep earth embankment Environment Agency Good 115 112GF22200301C04 protected by masonry surface (Grade 2) 112GF22200302C01 - Rock revetment toe, concrete Environment Agency 112GF22200302C04 access way, masonry Good 29 revetment and a concrete (Grade 2) wave return wall 112GF22200302C05 Shallow-sloped earth Environment Agency Very good 115 embankment (Grade 1) 112GF22200401C01 - Shallow-sloped earth Environment Agency Fair 100 112GF22200401C02 embankment (Grade 3) 112GF22200501C01 Elevated ground across road Environment Agency Good 115 and earth embankment (Grade 2)
3.1 Issues, Risks, Constraints and Opportunities Issues Area 1 is currently defended by a relatively narrow and shallow earth embankment for much of its length. This embankment lies between a wide intertidal saltmarsh area and a low lying area of farmland which has been identified as possible habitat mitigation (Area 5 – Northwick). Changes to the flood defence within Area 1 may result in environmental impacts due to potential loss of intertidal habitat or damage to hedgerows and other features important to a variety of native species, although such damage may also be mitigated by the ASEA project. The cumulative impact of works in Area 1 will be a key consideration during the option appraisal and design phases. The main areas identified for commercial and industrial development within the ASEA are in Areas 2 and 3, further south. This distribution of development makes the case for extending the coastal defences to Aust more difficult. Flood defence improvement works in Area 1 may also face problems in attracting top-up funding due to the relatively few assets that are protected by the existing embankment, and the long section of frontage affected. Risks The existing flood defence embankment from Severn Beach to Aust has a number of low spots within the defence, distributed throughout the study area. Hydraulic modelling indicates that these areas may result in overtopping in a 1:20 return period (5% AEP). The existing standard of protection offered at Severn Beach is higher than the adjacent sections of defence. The flood defences occupy a narrow and elevated strip of land between the existing coastline and residential and commercial development immediately behind the defence. Opportunities to raise existing embankments will be difficult as the expansion of the defence footprint is constrained by the development landward of the defences. Residual overtopping of the seawall at Severn Beach is presently managed by a flow channel behind the defence which drains through a number of small outfalls in the seawall. This may become unfeasible in the future as sea levels rise, causing the flapped valves to stay closed when discharge is required.
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Constraints The inspection and maintenance of a new defence along Area 1 should not create substantial issues due to the relatively good access throughout the frontage with clear space to the seaward and landward side of the crest of the existing embankment, and good access to all areas of the existing defences at Severn Beach. Changes to accessibility are expected in future years as the intertidal area seaward of the existing embankment responds to increased water levels as a consequence of climate change, narrowing the space for maintenance and inspection activities. If a local realignment defence option were to be progressed, the access to the site for inspection and maintenance equipment should be considered as a potential risk to be addressed during option development and design. Construction of new flood defences will be subject to an Environmental Permit, while any works required on the seaward side of the existing defences will require a Marine Licence if below the mean high water spring level. Both of these consents may be necessary for works along the existing defence alignment, although a preference for constructing on the landward side of existing structures may eliminate the need for a Marine Licence. Realignment further inland would also only require an Environmental Permit. Opportunities Although the preferred policy is to ‘Hold the Line’, opportunities for local realignments are not excluded from the appraisal. The various available alignment and defence techniques may offer an opportunity for environmental benefit, with the potential creation of saline habitats if realignment is adopted. 3.2 Defence alignment options Flood defence alignments were proposed within the previous, incomplete Avonmouth to Aust Tidal Defence Scheme proposals, were refined in the Avonmouth-Severnside Flood Management Optioneering project (Atkins, 2013), and were adopted as a starting point for the analysis conducted within this project. The alignments discussed in this section of the report relate to upgrading the existing flood defence structures and shorelines as well as realigned defences that would connect to higher ground further inland. The Avonmouth to Aust Tidal Defence Scheme project was stalled prior to completion of the options assessment process; however, conclusions have been drawn from the interim qualitative analysis for Severn Beach to Aust. Any improvement to the existing embankment was considered likely to be embankment raising, or possibly hardening if foreshore recession continued. No specific type of asset was defined for the two possible alignments towards the A403. The various options for aligning the flood defences in Area 1 are outlined in
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Figure 4.
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Figure 4 – Alignment options for Area 1. This map is reproduced from Ordnance Survey © material by Halcrow on behalf of the ENVIRONMENT AGENCY with the permission of the Controller of Her Majesty’s Stationery Office. © Crown copyright. Unauthorised reproduction infringes Crown copyright and may lead to prosecution or civil proceedings. Licence Number: 100026380 3.2.1 Coastal Defence – Existing alignment The Coastal Defence option will seek to retain and improve the flood defence along the existing alignment, avoiding the cost and compensation that will be necessary for new flood defences. The existing defences are largely composed of earth embankments, and the crest level will be increased to improve the standard of protection. Furthermore, risk of erosion due to increased wave action could be addressed by hardening of the seaward face of the embankment. The necessary increase in crest elevation of the defence may be achieved through a variety of engineering solutions. However it is likely that increasing the footprint of the defence by expanding towards the estuary would not be acceptable due to the negative environmental impact this would have on intertidal habitats. An increase in defence footprint may be achieved by widening the defence landwards, if this does not overly impact on existing properties and facilities. Alternatively, the crest elevation may be increased through the introduction steeper slopes or vertical faces that will retain the existing defence footprint. This may include retaining walls, steel sheet piles or rock structures, although such approaches will incur large capital construction costs. 20
Over time it is likely that the intertidal area between the existing flood defence and the River Severn will reduce in size as a consequence of sea level rise. This coastal squeeze may expose the existing defence to more significant erosive forces, leading to a need for a hardened defence and toe protection. While this need may be encountered during the design life of the structure it will be possible to adopt an adaptive approach that delays the implementation of these features until the issue becomes relevant. Historic mapping analysis in the Avonmouth to Aust Tidal Defence Scheme report (Atkins, 2006) indicated future saltmarsh stability to the south, with erosion likely to the north. These findings are supported by modelling outputs in the Severn Estuary Flood Risk Management Strategy Coastal Habitat Management Plan (CHaMP) (ABPmer and Royal Haskoning, 2006), which indicated an accelerating decline in intertidal habitat between 2006 and 2100. This may allow for the adoption of an adaptive management approach along this section of the coast. 3.2.2 Set Back Defence 1 – Realigned close to M4 Set Back Defence 1 provides a realignment option that delivers flood defence to Severn Beach and the areas identified for development within the ASEA, and allows natural evolution of the coast in Area 1. The specific alignment presented is a theoretical alignment that will require land purchase or agreement with landowners for defence construction. Avoiding maintenance of the existing defences will likely result in the long-term realignment of the coast further inland, particularly as sea levels increase as a consequence of climate change. A large number of residential and commercial properties and a large area of agricultural land would be afforded a standard of protection below 1 in 200 years (AEP 0.5%). Significantly the option provides no formal protection to the A403 highway, which acts as an important transportation route for commercial and industrial activities within the ASEA. The specific defence approach adopted is dependent on the conditions expected at the site as the coast realigns. The defence is likely to be very sheltered due to the hard defences further south, and the very short fetch that would be expected to the defence. As such the primary function of the defences will be to prevent inundation during extreme tidal and surge conditions, which may be achieved through the construction and modification of existing earth embankments. There is also the possibility of retaining the existing flood defences with relatively simple improvement works, and construction of a secondary defence line further inland to control flooding during extreme events. Such an approach will allow continued use of the area seaward of the secondary defence, while protecting the greater number of assets and associated value further inland. The area seaward of the secondary defence would be afforded a standard of protection less than the target 0.5% AEP. The presence of two flood defence structure would introduce higher maintenance costs than a single defence structure. 3.2.3 Set Back Defence 2 – Realigned close to A403 Set Back Defence 2 provides a long term realignment of the coastal defence inland, creating a flood defence aligned to the A403 road, broadly parallel with the existing flood defence. The inland location would result in a number of residential properties and a large area of agricultural land being afforded a standard of protection below 1 in 200 years (AEP 0.005%). As the influence of climate change expands it is likely that the areas seaward of the realigned defences would be inundated on a more regular basis which may require the permanent relocation of residents. The defence line will seek to take advantage of areas of high ground further inland as well as any opportunities offered by the A403 infrastructure. The location substantially inland is unlikely to expose the defence to significant wave action in the short- or medium-term, and the hard defences further south will provide a high degree of protection from wave action. As such it is likely that any new structures will be earth embankments, introducing new structures between areas of naturally high ground and suitable existing structures. It may be possible that an adaptive approach can be adopted, with increasing bank height over time as the influence of sea level rise is realised.
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Similar to Set Back Defence 1, this option also has the potential for retaining the existing flood defences as the primary defence line, with secondary flood defences further inland to control flooding during extreme events. 3.3 Stakeholder comments Preliminary feedback from some stakeholder organisations regarding the alignment options indicated that options for major coastal realignment should be discounted due to the impact on residential property and important infrastructure and the divergence of this approach from the agreed conclusions of the Severn Estuary Strategy. However, the stakeholders were divided on the best way forward, with some indicating a preference for retaining a flood defence wholly on the existing alignment, while others indicated a preference for a hybrid option that capitalises on the potential benefits of locally realigned defences alongside re-use of parts of the existing structure. This may be achieved through a combination option with primary and secondary defences. The potential for realignment in the centre of Area 1 (north of Chestle Pill) was also highlighted as an opportunity to create additional saltwater habitat that might be needed for compensation of the scheme. Ecologically the existing alignment was considered to create a smaller ecological impact than the realignment options. While realigning defences inland would reduce the potential for coastal squeeze, the footprint of a new defence will be significantly larger than the increased footprint of an elevated defence at the existing defence alignment. A realigned defence may also lead to loss of land identified for habitat mitigation, therefore the alignment for Area 1 should be cognizant of the objectives of the overall project.
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4 Area 2 – Avonmouth Docks Area 2 comprises approximately 2.6km of the right bank of the River Avon Estuary and a 3.4km section of the Severn estuary between the mouth of the River Avon and Chittening. The Area 2 frontage connects the River Avon embankment to the south east of the M5 flyover and the entrance to Avonmouth docks. It also connects the Avonmouth docks with the defence embankment next to the railway at Chittening. Overall the coast and river are characterised by relatively higher land than other parts of the ASEA, however any overtopping of defences will cause rapid flows of floodwater through the docks and into the lower-lying development further inland.
Elevation (mOD)
Figure 5 – Coastal defences in Area 2 Avonmouth Docks. This map is reproduced from Ordnance Survey © material by Halcrow on behalf of the ENVIRONMENT AGENCY with the permission of the Controller of Her Majesty’s Stationery Office. © Crown copyright. Unauthorised reproduction infringes Crown copyright and may lead to prosecution or civil proceedings. Licence Number: 100026380
The land between the existing flood defences and the M5/M49 highway is occupied by significant residential development and industrial and transport infrastructure. Avonmouth comprises a large number of residential properties within the southern portion of Area 2, supported by the M5, M49, A403 and a local railway line that passes through Avonmouth and runs adjacent to the Severn estuary coast. The Avonmouth docks occupy a large part of the western side of Area 2. The right hand bank of the River Avon affords protection to this development through elevated flood embankments, including recently elevated flood banks close to Avonmouth docks that were constructed in 2002. Much of the flood defence on the Severn estuary coast is afforded by elevated ground and supplemented by narrow flood walls. Similar to Area 1, the crest levels of flood defences in this Area vary along the shoreline providing varying standards of protection. Details of the flood
23 defence assets within Area 2 are presented in Table 3, including a description of the defence, the owner responsible for the maintenance of the asset, the condition (estimated from visual inspection) and the estimated residual life extracted from the coastal defences technical note (CH2M, 2016). Table 3 Area 2 flood defence assets
AIMS ref. Description Operator Condition Residual life (yrs) N/A Avon estuary embankment Bristol Port Fair/Poor 0-50 Company (Grade 3/4) N/A High ground at site of future Bristol Port Fair N/A sea container facility Company (Grade 3) 112GF22200101C01 - Avonmouth concrete block Bristol Port Fair 20-30 112GF22200101C02 wall Company (Grade 3) N/A Avonmouth coastal earth Bristol Port Fair 100 embankment Company (Grade 3)
4.1 Issues, Risks, Constraints, and Opportunities Issues Increasing the crest elevation of both the embankments around Avonmouth docks and the defences along the Severn estuary faces potential difficulties due to the additional footprint that may be required to accommodate higher structures. A design that increases the elevation of the earth embankments will need to resolve issues regarding habitat impacts, embankment stability, and maintenance needs. Changes to the small wall along the Severn Estuary may also face difficulties with space for revised flood defences due to the proximity of industrial pipelines and transport infrastructure. Risks The defences along the River Avon offer a potentially higher standard of protection due to higher crest levels than other sections of coastal defence along the Severn Estuary, however the permeability of the existing structure may reduce the effective standard of protection. The new embankment around the southern side of Avonmouth docks, constructed in 2002, provides a clearly defined profile that can be effectively maintained in the future. Some other areas of flood defences are particularly susceptible to flooding, including the lock gates within Avonmouth docks and a narrow flood wall close to the fuel storage depot infrastructure within the docks. These areas will be unlikely to provide effective flood protection in the future. Constraints One of the most significant constraints on the implementation of a scheme in Area 2 is the potentially negative impact of the defence structure or construction works on activities within Avonmouth docks. The existing lock gates that afford access to shipping to the floating harbour do not operate as flood defence gates; they are designed to hold water within the dock only and must be opened at high tides to allow filling of the dock and prevent off-seat loading. Therefore, to provide an effective flood defence, the project would need to include the replacement of the existing unused central gates with new gates that are dedicated to withstanding elevated coastal water levels. Replacement of the gates will affect access into the docks for vessels during construction. Access to areas within the docks will also require permission from the port operators, complicating the maintenance and inspection regimes for flood defences.
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Construction of new flood defences will be subject to an Environmental Permit, while any works below mean high water spring level will require A Marine Licence. Both of these consents may be necessary for works along the existing defence alignment. Although a preference for constructing on the landward side of existing structures still applies in Area 2, and may eliminate the need for a Marine Licence. If constructing landward is not possible there may be imperative reasons of overriding public interest (IROPI) for construction that impacts the adjacent Natura 2000 site. Realignment further inland may only require an Environmental Permit. Opportunities Area 2 will offer larger flood defence benefits than either Area 1 or Area 3 due to the protection of large numbers of residential properties, Avonmouth docks, and other commercial and industrial facilities. It is possible that the larger benefits which might be realised in Area 2 will support the construction of new defences in coastal areas as well as the upgrade of some existing structures. 4.2 Defence alignment options Flood defence alignments were proposed within the incomplete Avonmouth to Aust Tidal Defence Scheme project and were adopted as a starting point for the analysis conducted within this project. The alignments discussed in this section of the report relate to upgrading the existing flood defence structure as well as realigned defences that will make use of existing infrastructure. The various options for aligning the flood defences in Area 2 are outlined in Figure 6.
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Figure 6 – Alignment options for Area 2.
This map is reproduced from Ordnance Survey © material by Halcrow on behalf of the ENVIRONMENT AGENCY with the permission of the Controller of Her Majesty’s Stationery Office. © Crown copyright. Unauthorised reproduction infringes Crown copyright and may lead to prosecution or civil proceedings. Licence Number: 100026380 4.2.1 Coastal Defence – Existing alignment The Coastal Defence option will seek to retain the flood defence along the existing alignment, offering potential cost savings and minimising environmental impacts by utilising existing structures. To accommodate the impacts of climate change, the standard of protection of the different types of existing structures will be increased through various engineering techniques, including modifications to existing arrangements and fuller reconstruction/replacement. It may be possible to increase the level of the existing earth embankments along the River Avon, although there is very little space between the intertidal area in the Avon and access roadways behind the flood defences. It is likely that increasing the footprint of the defence into the estuary 26 would not be acceptable due to the environmental impact on the intertidal areas, although it may be justified if there are no realistic alternatives. It may be possible to achieve a higher crest elevation with a narrowed crest width or through the introduction of a small flood wall, though this is likely to impact the maintenance regime of the structure. The flood defences along the Severn Estuary currently comprise high ground with a short and narrow concrete blockwork wall. It is not anticipated that the wall will offer effective flood protection as water levels increase as the short wall will not be able to effectively resist greater water depths. It is likely that the wall will be replaced by a larger structure able to effectively resist the deeper water depths predicted along the defence, as well as the more significant wave conditions which might propagate to the wall location. Within Avonmouth docks the replacement of the lock gates may be pursued to increase the crest level of the structures, however the practicality of such a change will need to be established through further engagement with Bristol Ports Company. Over time it may be expected that the intertidal area within the River Avon and the Severn Estuary would be reduced due to the fixed defence location, allowing larger wave conditions to impinge on the coastal defences. Area 2 formed part of a larger Habitat Behavioural Unit (HBU) within the Severn Estuary Flood Risk Management Strategy CHaMP (ABPmer and Royal Haskoning, 2006). For this HBU the CHaMP suggested erosion of the intertidal area over this century, with a potential loss of 25% of the 2006 habitat area by 2100. This finding contrasts with the results of the Avonmouth to Aust Tidal Defence Scheme (Atkins, 2006), which suggested future expansion of saltmarsh areas. 4.2.2 Set Back Defence 1 – Realigned behind Avonmouth docks Set Back Defence 1 provides realignment of the flood defence from the coastal edge of the Avonmouth docks to the landward boundary of the docks, seaward of the railway line. This alignment will need to allow construction of a flood defence that can be readily accessed and managed by the Environment Agency, although it is recognised that the proximity to Network Rail infrastructure make this a challenge. The construction of a flood defence landward of the Avonmouth docks would leave the port facility exposed to increased flood risk unless additional or duplicate flood defences were also constructed by Bristol Ports along the coast. The construction of such additional flood defences may seem inefficient, and may lead to complications in proving benefits in the economic assessment for FDGiA funding, however this option may offer a suitable compromise in providing flood defence to enable development of the ASEA while not impacting operations at the dock. Access to the port facilities across the realigned defences might be achieved by elevated roadways or gates in the defence. This could potentially impact operations within the dock, by restricting the size of vehicle or loads carried on the road network. The inland location will not expose the new structures to wave action, therefore it will not be necessary to introduce significant armouring to resist erosive forces. It will be difficult for the realigned defence to be constructed as an earth embankment due to the large footprint necessary and the constrained space between the Avonmouth docks and the railway line. Alternatively, a vertical flood wall may be constructed to provide the necessary standard of protection to the residential properties and the transport infrastructure further inland. 4.2.3 Set Back Defence 2 – Realigned through Avonmouth Set Back Defence 2 provides a variety of realignments further inland, between the railway line and the M49 and landward of the Avonmouth settlement, Avonmouth docks, and the local railway lines and A403. The inland alignment will take advantage of higher ground where appropriate, and will afford ready access to Environment Agency staff for inspection and maintenance. Such a significant realignment inland may be considered appropriate due to the high degree of potential complexity in achieving a flood defence along the existing coastline or between Avonmouth docks and the railway line.
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The alignment landward of Avonmouth would expose a large number of residential properties to future flooding, as well as compromising the flood protection of Avonmouth docks, the railway line and the A403. The defence would also need to accommodate several road crossings either needing changes in elevation or through flood gates that would need to be operated during flooding. The flood defences are not expected to be exposed to permanent wave action or tidal fluctuation, therefore the construction can be relatively simple, such as an embankment or a flood wall. It is likely that a narrow footprint will be preferred due to the need to construct the defence within the existing developed areas. 4.3 Stakeholder comments Preliminary feedback from some stakeholder organisations indicated that the options for realignment away from the coast should be discounted as these would: • lead to duplication of the defence structures already in place within the Port area; • conflict with the strategic objectives of the Port to maintain a coastal defence alignment; • fail to protect important infrastructure or residents in Avonmouth; and • require a complex and expensive solution, particularly in accommodating multiple road and rail crossings. While there was broad agreement that the existing alignment of defences is the most appropriate solution for Area 2, stakeholders identified several potential issues that need to be addressed. 1. The successful implementation of an increased crest elevation along the existing alignment will require detailed agreement with the port; 2. The construction activities associated with improving the standard of protection in the port, such as the replacement of lock gates, should not impact the commercial operations in the port; 3. Issues regarding access for future maintenance activities should be clarified and addressed with the port operators; and 4. Port defences must be flexible to the potential future development of the proposed deep sea container unit (DSCU), as this would form part of the flood defence. The programme for this work may also necessitate the construction of temporary flood defences until the DSCU is completed. Subsequent discussion with Bristol Ports Company provided a strong endorsement for upgrading the existing coastal defences. This will provide the least disruption to port activities both during construction and throughout the design life, while protecting the most assets within the Area. Phasing of defence improvements will also be possible, allowing an adaptive approach to address the most at risk sections throughout the design life.
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5 Area 3 – Central Embankment and Outfalls Area 3 comprises a 4.6km frontage of the Severn Estuary between Chittening and Severn Beach. In the southern section of Area 3 the flood defences are fronted by an area of intertidal saltmarsh which helps reduce wave action and overtopping at the defence line. The railway line embankment comprises a high embankment at the coast in this section of the frontage, however closer to Severn Beach the railway line moves further inland. The land area is generally low-lying behind the flood defences, particularly at Severn Beach where much of the residential properties occupy ground that is significantly lower than the flood defence crest level.
Elevation (mOD)
Figure 7 – Coastal defences in Area 3 Central outfalls. This map is reproduced from Ordnance Survey © material by Halcrow on behalf of the ENVIRONMENT AGENCY with the permission of the Controller of Her Majesty’s Stationery Office. © Crown copyright. Unauthorised reproduction infringes Crown copyright and may lead to prosecution or civil proceedings. Licence Number: 100026380
The area behind the flood defences is used for a wide range of purposes, including transportation along the railway line and the A403 highway, residential development at Severn Beach, industrial facilities (including power generation, waste disposal, and distribution), and agriculture. It is this area that has the greatest opportunities for new industrial and commercial development. There are a variety of existing flood defence structures in Area 3. The southern section is formed from a wide intertidal area in front of the railway embankment, with earthwork banks connecting to high ground at Chittening and the former ICI waste disposal site, and a formal flood defence embankment and seawall between south of Severn Beach and the Second Severn Crossing. The crest 29 level of the defences in the southern and middle sections of Area 3 are have a varying crest level. However, the formal flood defences within the Severn Beach area provide a consistent crest level and standard of protection. Details of the flood defence assets within Area 3 are presented in Table 4, including a description of the defence, the owner responsible for the maintenance of the asset, the condition (estimated from visual inspection) and the estimated residual life extracted from the coastal defences technical note (CH2M, 2016). Table 4 Area 3 flood defence assets
AIMS ref. Description Operator Condition Residual life (yrs) 112GF22200201C01 - Railway Line/ (Fluctuating de Environment 112GF22200201C07 facto Flood Defence) Agency and Good 115 & Network Rail (Grade 2) 112GF22200202C01 112GF22200202C02 - High ground (part of ICI waste N/A Good n/a 112GF22200202C03 disposal site) (Grade 2) 112GF22200202C04 - Masonry revetment and earth Environment Good 29 112GF22200202C06 embankment Agency (Grade 2) 112GF22200301C01 Reinforced concrete seawall Environment Good/Fair 35-55 Agency (Grade 2/3) 112GF22200301C02 Reinforced concrete seawall Environment Fair 29 with masonry revetment Agency (Grade 3)
Direct modification and raising of the railway line to improve its waterproofing and function as a flood defence to Area 3 and the wider ASEA has been considered. Previous discussions with Network Rail on similar flood risk management projects have clarified that use of rail infrastructure for flood defence is forbidden by the organisation. The requirement for the existing railway embankment to resist wave action will introduce new loading conditions on the structure, which may exceed its primary design requirements, while the different environmental conditions anticipated at a formal flood defence may necessitate additional maintenance activities and higher costs for Network Rail. Changes to the transportation infrastructure would also result in permanent and temporary impacts on services, created by construction and maintenance activities of the flood defence. 5.1 Issues, Risks, Constraints and Opportunities Issues The flood defences in Area 3 include a range of defence types, with differences in ease of access or space for construction. The flood defences in the southern section are largely constrained by the railway line, which is adjacent to a wide intertidal area and forms the de facto flood defence. Previous studies indicated that flood defence works would not be immediately required as the railway embankment crest is above the present 1 in 200-year water level. However, the resilience of the embankment may be in doubt if the upper section of the embankment doesn’t provide effective flood defence dues to the porous nature of the ballast material. The use of the railway as a de facto defence is dependent on the continued existence of the intertidal saltmarsh that moderates wave action on the toe of the embankment. It will be challenging to integrate additional structures close to, or within railway land while ensuring adequate access. At the former ICI waste disposal site there is a wide area of relatively high ground between the existing coast and the assets further inland. This area offers potential space for realigning the coast as well as a possible location for a site compound. However, ground
30 contamination may be an issue, and it is unclear what mitigation may be needed if exposure of waste material cannot be avoided. Risks Existing defences north and south of the section of undefended railway line are in good condition and minor raising of embankments to accommodate climate change affects can be incorporated into the project. Whilst the existing railway line is above the current 1:200 (0.5%) AEP flood level, the likely poor condition of the railway means that it is reliant on the existing saltmarsh to protect it from erosion. There are a number of surface water and watercourse outlets along the Area 3 frontage. These are prone to blockage from siltation, and the Environment Agency carries a maintenance liability for these outfall assets. Constraints Atkins (2006) indicated slow erosion of the saltmarsh to the south and slow expansion of the saltmarsh to the north of Area 3. Area 3 was part of a larger HBU (including Area 2) within the Severn Estuary Flood Risk Management Strategy CHaMP (ABPmer and Royal Haskoning, 2006). This work suggests short-, medium- and long-term loss of intertidal habitat. It is therefore considered likely that maintaining the existing defence line for Area 3 would lead to coastal squeeze in some areas due to the relatively wide intertidal habitats that front some of the flood defences. Higher water levels may be expected to encourage changes in the habitat types and an overall reduction in intertidal habitat, requiring compensation. Construction of new flood defences will be subject to an Environmental Permit, while any works below mean high water spring level (such as outfall structures) will require a Marine Licence. Both of these consents are likely to be necessary for works along the existing defence alignment, while realignment further inland may only require an Environmental Permit. Opportunities Flood defences in Area 3 offer a relatively high standard of protection to a substantial residential development at Severn Beach (approximately 1000 properties) as well as the large and varied industrial development within the ASEA. Successful implementation of a flood defence in Area 3 will be dependent on correctly programming investment in flood defence works to match the increased risk created by climate change. Effective management of the drainage network and outfalls within Area 3 is a significant concern for the project. The capability of the rhine system to manage surface drainage will contribute to the successful development of the ASEA, with expectation that increased capacity will be required to address climate change in the future. The management of surface drainage may be addressed through modification/refurbishment of existing structures, the construction of new drainage infrastructure, or the introduction of temporary storage areas, with a balance required between the potential benefits offered and the land take and cost required to implement. 5.2 Defence alignment options Possible flood defence alignments were proposed within the incomplete Avonmouth to Aust Tidal Defence Scheme and were adopted as a starting point for the analysis conducted within this project. The alignments discussed in this section of the report relate to upgrading the existing flood defence structures as well as realigned defences that will capitalise on higher ground further inland. The Avonmouth to Aust Tidal Defence Scheme project was stalled prior to completion of the options assessment process; however, conclusions have been drawn from the interim qualitative analysis for Severn Beach to Aust. Any improvement to the existing embankment was considered likely to be
31 embankment raising, or possibly hardening if foreshore recession continued. No specific type of asset was defined for the two possible alignments towards the A403. The various options for aligning the flood defences in Area 3 are outlined in Figure 8.
Former ICI waste disposal site
De facto railway defence, protected by saltmarsh
Existing earthwork embankment
Figure 8 – Alignment options for Area 3. This map is reproduced from Ordnance Survey © material by Halcrow on behalf of the ENVIRONMENT AGENCY with the permission of the Controller of Her Majesty’s Stationery Office. © Crown copyright. Unauthorised reproduction infringes Crown copyright and may lead to prosecution or civil proceedings. Licence Number: 100026380
5.2.1 Coastal Defence – Existing alignment The Coastal Defence option will seek to retain and improve flood defence along the existing alignment, offering potential savings in materials. Increasing the standard of protection offered by 32 the flood defences will involve reconstruction and replacement of existing structures to increase the crest level as well as measures to improve resistance to erosion. Modifying the de facto railway embankment along the Severn estuary will be complicated by the issues involved in accessing the Network Rail asset to improve and maintain the flood defence. Investment in the railway embankment by Network rail is likely to be low priority. Therefore investment from Network Rail to benefit both transport and flood defence are unlikely. It is unlikely that the construction of a new embankment seaward of the defence will be acceptable due to the environmental impact of such works on the designated intertidal habitat. Adopting a narrower form of defence with a smaller footprint close to the existing embankment may address the possible issues of access while minimising the environmental impact, although will incur higher costs due to the need for an entirely new structure. Creating a formal defence along the high ground at the former ICI waste disposal site can be achieved in a number of ways. Constructing a rock or concrete revetment would increase the crest elevation of the area to provide a consistent standard of protection and would protect against erosion. This would however fix the coastal position and lead to coastal squeeze in front of the defence. Upgrading the flood defences at Severn Beach is complicated by the proximity of development to the existing flood defences. Increasing the crest level of the masonry revetment and earth embankment structure could involve steepening the embankment slopes, however this would make maintenance more challenging. Expansion of the footprint in a seaward direction would impact the intertidal habitat and would require compensation. Elevation of the reinforced concrete seawall further north may be possible, although the residual life of the steel sheet piles in the structure may necessitate more significant work over time. The intertidal area in the south of Area 3 may be expected to narrow over in the future due to the fixed flood defence, allowing larger wave conditions to impinge on the coastal defences. Modification to the flood defences will therefore include provision to more effectively resist erosion, particularly at the structure toe. 5.2.2 Set Back Defence 1 – Realignment behind the railway Set Back Defence 1 provides realignment of the flood defence from the de facto flood embankment at the railway line to a new structure along the A403. This will create a flood defence immediately landward of the railway line for much of Area 2, before moving further inland behind Severn Beach. The alignment will afford protection to the industrial development at Chittening and areas further inland to the north of Hallen Marshes, however it will not provide flood defence to the railway line or the residential and commercial properties at Severn Beach. The alignment will capitalise on existing features, making use of the higher ground in the natural topography further inland of Severn Beach. This approach will minimise the work necessary to provide a continuous flood defence with consistent crest elevation, however it may still require long sections of new defence. It is likely that the flood defence will not be exposed to wave action as the railway line will break incident waves and will dissipate much of the wave energy. As such the realigned defence is most likely to be achieved through changes to the road embankment. It may be necessary to adopt a narrower form of defence to ensure the structure within the existing built environment if modification to the road embankment is not possible. Greater space is afforded for the defence inland of Severn Beach with a broader capability to accommodate defences with a wider footprint. The influence of sea level rise will change the morphology of Area 3, with narrowing of the intertidal habitat. The railway line will likely experience greater erosion than present, and may lead to infrastructure damage and interference with transport operations.
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5.2.3 Set Back Defence 2 – Realignment adjacent to A403 Set Back Defence 2 provides realignment behind the industrial development at Chittening and the de facto flood embankment at the railway line to a new structure along the A403. The realignment will provide flood defence to the main area for future development within the ASEA, however a wide number of assets closer to the coast will not be protected by the realigned food defence. The alignment will take advantage of the higher ground along the A403 road and the ground further inland. Similar to Set Back Defence 1, this alignment will take advantage of the higher ground elevation at the A403 providing flood defence to inland areas and minimising the amount of work necessary to increase the level of flood defences. The defences will not provide flood protection to the residential areas at Severn Beach and will fail to defend the railway line from inundation more regularly as sea levels rise. Upgrade of the defence along the A403 road will protect the road transport network, but as such will pass behind the industrial development at Chittenting, providing a reduced standard of protection at this location. As with Set Back Defence 1, it is unlikely that the new flood defence will be exposed to wave action as the railway line will break incident waves and will dissipate much of the wave energy affecting this Area. Raising of the road embankment may be pursued, however if this is not possible the introduction of a new and narrow flood defence structure seaward of the A403 may be necessary. The influence of sea level rise will change the morphology of Area 3, with narrowing of the intertidal habitat. Damage to the transport infrastructure at the railway may be expected as erosion increases through with change to the nearshore water levels and wave heights over time. 5.2.4 Surface drainage (Rhine network and outfalls) Surface drainage is a significant concern within Area 3, with the low lying area behind the existing railway embankment intended for future industrial development. The area is currently drained by a rhine network with smaller drainage channels feeding larger rhines, which in turn discharge through the railway embankment into the Severn estuary. The outfalls within the study area are described in Table 5 and Figure 9. Table 5 Rhine outfall asset data
AIMS ref. Description Owner 112GF22200401C01001 Chestle Pill – twin culverts, approximately 20m Environment Agency long and of a 2m diameter, with a flap valve on the downstream end of each culvert 112GF22200201C07001 New Pill – twin culverts, approximately 20m long Environment Agency and of a 2.1m diameter, with a flap valve on the downstream end of each culvert 112GF22200102C04001 Stup Pill – twin culverts, approximately 5m long Environment Agency and of a 1.5m diameter, with 2.1m2 flap valves on the downstream end of each culvert 112GF22200102C02001 Mitchells Salt – twin culverts, approximately 5m Environment Agency long and of a 1.5m diameter, with flap valves on the downstream end of each culvert 112GF22200101C04001 Holes Mouth – Four adjacent culverts each with a Environment Agency flapped outfall (three metal gates and one timber) 112GF22200101C01001 Kings Weston (also referred to as Elbury Outfall) Environment Agency – two adjacent culverts (1.5m x 2.1m) each with a timber flapped outfall
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AIMS ref. Description Owner 112GF22200501C01002 Cake Pill – reinforced concrete culvert and Environment Agency headwall structure approximately 1.2m high, 1.2m deep and 22.4m long 112GF22200302C05002 Cotteralls Pill – single culvert with a metal flap Environment Agency gate
Cotteralls Outfall
Chestle Pill
Industrial intake
New Pill
Stup Pill
Holes Mouth Mitchells Salt
Kings Weston
Figure 9 – Outfall locations as presented in the scope for the Avonmouth Severnside Enterprise Area (ASEA) Ecology Mitigation and Flood Defence Project. This map is reproduced from Ordnance Survey © material by Halcrow on behalf of the ENVIRONMENT AGENCY with the permission of the Controller of Her Majesty’s Stationery Office. © Crown copyright. Unauthorised reproduction infringes Crown copyright and may lead to prosecution or civil proceedings. Licence Number: 100026380
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Work to establish whether the existing drainage network has sufficient capacity to effectively discharge surface flood water has not been completed, but will inform final option selection in this area. While work is outstanding, the broad approaches which may be adopted can be described, along with the advantages and disadvantages for use in this project. Increase desilting activity The estuary coast of the River Severn experiences substantial sediment deposition which has previously led to siltation of the outfalls and reduced efficiency. The rhine network itself may have experienced silting as the drainage of surface water transported sediment from higher ground. If the storage capacity within the existing network, or discharge capacity through the outfalls is insufficient to handle the surface drainage, it is possible to desilt the coastal outfalls and potentially the rhine network. Additional culverts Additional culverts offer the potential to increase the total capacity of the drainage system. This will allow more effective management of surface water drainage during high flow rates, however it may result in lower flow speeds during low flow conditions and could result in additional sedimentation. Construction of additional culverts may create significant disruption to the railway, the A403 and other access routes. Increase size of rhine network Increasing the size of the rhine network will increase the storage capacity and potential flow rate through the open channel areas, however there is still potential difficulty in discharging through the existing culverts. The widening and deepening of the existing network may create additional environmental opportunities. Additional storage (dry ponds) Where surface flooding exceeds the discharge capacity of the outfall and rhine network, and exceeds the capacity for temporary storage within the existing rhine network, the temporary storage within larger defined areas may be possible. The excavation of such areas will need to be cognizant of the local geotechnical conditions as well as potential historic environment assets. More regular inundation of such areas may lead to changes in the local groundwater level, resulting in changes to habitats. 5.3 Stakeholder comments Preliminary feedback from some stakeholder organisations regarding the alignment options indicated that the realignment along the A403 would be less preferred due to the lack of protection to the railway line and industrial facilities seaward of this alignment. There was general agreement that the existing defence alignment is broadly appropriate, although there was appreciation that a hybrid option capitalising on the benefits of the existing defence alignment at Severn Beach and a realignment along the back of the railway line might be preferable. The selection of a preferred option will be dependent upon further engagement with Network Rail and other agencies. Specific issues discussed by stakeholders included the foreshore erosion close to the flood defences at Severn Beach in the northern section of Area 3. It was suggested that the defence design and alignment may be amended to address the erosion issue, although it is unclear how this would be incorporated into the existing flood defence scheme. Maintaining the existing defence alignment in the middle section of Area 3 may create potential issues with coastal squeeze, narrowing the intertidal area as sea levels rise, although the actual impact is unclear at this stage. Constructing a formal embankment in this section of Area 3 will have further ecological impacts through the structural footprint.
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6 Area 4 – Hallen Marsh Area 4, known as Hallen Marsh (Figure 10), lies to the north east of Avonmouth, adjacent to existing commercial and industrial developments. It is bordered to the east by the M49 motorway, and to the south by a railway line. A number of public rights of way cross the site.
Area 4 Hallen Marsh
Figure 10 - Area 4 (Hallen Marsh) Identified mitigation area
This map is reproduced from Ordnance Survey © material by Halcrow on behalf of the ENVIRONMENT AGENCY with the permission of the Controller of Her Majesty’s Stationery Office. © Crown copyright. Unauthorised reproduction infringes Crown copyright and may lead to prosecution or civil proceedings. Licence Number: 100026380 The whole of Area 4 is characterised by predominantly low-lying ground, with some small areas of raised land within the site. It comprises approximately 111ha of semi-improved species poor grassland and arable land, predominantly used for agriculture. Criss-crossing the site are a number of ditches, some of which form the primary, flowing rhine network managed by the Internal Drainage Board (IDB). The land is also characterised by a network of hedgerows, of varying quality and density. 6.1 Habitat creation requirement Area 4 has been identified as having the potential to create mainly (freshwater) wet grassland habitat, with some ephemeral bodies of water (such as shallow scrapes that dry-up in summer) which can be reconciled with continued agricultural practices such as livestock grazing or management for hay or silage. Creation of a small number of ponds (permanent open water habitats) could also be accommodated within the site. While this habitat will be used as mitigation for the industrial and commercial development within the ASEA, the impacts on farming will need to be addressed. Table 6 provides a summary of the habitat requirements of the qualifying species and qualifying assemblage of birds that have been ‘scoped in’ for this project (Cresswell Associates, 2011).
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Table 6 - Summary of habitat requirements of wintering wildfowl and waders Species ‘scoped in’ Food type Habitats & specific requirements (Cresswell 2011) Gadwall Stems, leaves and Gravel pits, lakes, reservoirs and coastal wetlands in winter. seeds Breeding gadwalls found in the shallow vegetated edges of lakes and gravel pits. Shallow water - depth not exceeding
0.30m 1 Teal Seeds and aquatic Commonly found in sheltered wetlands. Shallow water - invertebrates depth not exceeding 0.20m Mallard Seeds, acorns and Wide range of wetland and open water habitats. Shallow berries, plants, water - depth not exceeding 0.35m Dabbling ducks insects and shellfish Shoveller Small insects and Open wetlands, such as wet grassland or marshes with plant matter sifted some emergent vegetation. Shallow water - depth not
from the water exceeding 0.30m
Pochard Plants and seeds, Open lakes and gravel pits. Deep water areas - at least 1m 2 snails, small fish and deep but also sloped sides to enable easy access and
insects egress. Tufted duck Molluscs, insects and Gravel pits, lakes, reservoirs. Deeper water - depth between
Divingducks some plants 0.35m and 5.0m Lapwing Worms and insects Found on wetlands with short vegetation. In winter they flock on pasture and ploughed fields. Curlew Worms, shellfish and Feed on mud or very soft ground, searching for worms and
shrimps other invertebrates with their long bills.
3 Common snipe Small insects, Edges of pools in well-vegetated wetlands including worms and
Waders insect larvae
A total of 111ha of land is potentially available in Area 4. However, some of the land may not be desirable for creation of new wetland habitat, due to the existing landscape and/or wildlife value (e.g. existing areas of woodland and thick hedgerows). A Phase 1 habitat survey has been undertaken (reference the CH2M report, once completed) which identifies areas of particular ecological value that should be retained, or could be incorporated within a new wetland habitat landscape. The main target habitat considered during this high-level appraisal for Area 4 is wet grassland, also known as coastal & floodplain grazing marsh. This habitat is of particular value to wintering and breeding wading birds, such as lapwing, curlew and common snipe. Wet grassland can be defined as periodically inundated pasture or meadow with ditches which maintain the water levels, containing standing brackish or fresh water. Sites may contain seasonal water-filled hollows (scrapes) and permanent ponds with emergent swamp communities. The grassland is often species-poor due to agricultural inputs and nutrient loads in the flood water.
1 Dabbling ducks search for food sifting through surface water, up-ending in the shallow reaches and often dabbling in the mud. Content with shallower and more restricted bodies of water than diving ducks. Generally feed in and around aquatic and marginal vegetation. Flooding releases seeds and invertebrates from vegetation, so is an important requirement for this species group. Dabbling ducks benefit from a large edge/surface area ratio on flooded areas (i.e. lots of emergent vegetation - seed sources).
2 Diving ducks dive and feed at the bottom of the water, often many feet below the surface. Require deep water (>2m) with high densities of invertebrates in sediment.
3 Waders – overwintering waders require soft, damp soil and high water tables. Winter flooding to create islands of grassland and shallow open water suitable for roosting. 38
Restoration or creation of wet grassland usually depends on raising water levels, so the availability of water is a crucial factor. Potential water sources include rainfall, surface water and groundwater. The water regime required for a site to support wintering waders includes maintenance of a high water table during the late autumn and winter months, with ‘splashy’ conditions over the whole field and/or shallow flooding from 1 to 30 cm over up to 30% of the field. Water levels should ideally be allowed to fluctuate to avoid stagnation. 6.2 Habitat creation process Delivering the required area of wetland habitat will be dependent on the availability of suitable land. The specific approaches used to create the habitats will be developed during subsequent stages of appraisal and outline design. Subject to landowner negotiations and other constraints, habitat creation may be maximised throughout the whole of Area 4 through the creation of connected habitats. Parts of the site could be hydrologically and physically connected through, for example, site-wide management of the rhines and removal of some of the hedgerows. This would enable the creation of an open, diverse mosaic of new wetland habitat (wet grassland, scrapes, ponds, lakes) together with retention of existing ecologically diverse features of the site, such as woodland areas, mature, dense hedgerows and existing ponds. If a smaller area of total land is available it may require the creation of discrete independent habitat ‘units’ which focus on creating specific conditions, e.g. one area of wet grassland and a separate area of open water habitat. These habitat units could then be managed independently of adjacent fields or units, without consideration of connectivity with existing or other new habitat areas. This could provide more flexibility in terms of negotiation with landowners and could also enable site specific hydrological requirements to be accommodated. Agricultural management on a field-by-field basis would be easier to achieve, but regardless of the approach taken the overall aim of the work will be to deliver the maximum area of habitat mitigation as possible within the constraints posed by Area 4. 6.3 Issues, Risks, Constraints and Opportunities There are a number potential issues, constraints and risks that will need further consideration during the more detailed option appraisal and outline design stages of the project. These include: • The need for a buffer zone surrounding the mitigation habitats may be necessary to ensure that the habitats are functional. The introduction of such an area will restrict the locations within Hallen Marsh which might be able to contribute to habitat mitigation areas, and may require changes to the existing landscape. • Areas suitable for the creation of required habitats will be affected by the ground conditions within Hallen Marsh. The soil characteristics and proximity to rhines will influence whether the habitat mitigation scheme is viable. • Ensuring changes to the landscape and habitats within the mitigation area is acceptable to users. The existing pasture and agricultural use of Hallen Marsh will be retained after the mitigation works, however the changes introduced to the landscape are likely to affect productivity of the area. It will be critical to reach agreement with tenancy owners over use of the land, potentially provide compensation for reduced productivity, or land purchase if required. • There may be some resistance or a presumption against penning of water levels in the rhines, particularly Stup Pill Rhine or other main arterial drains, due to the possibility of raising water levels upstream and causing capacity issues in these locations. Use of in-channel sluice or weir structures to pen water levels may also require significant mitigation to comply with the Eel Regulations. • Scrapes and ponds/lakes would need to be carefully designed, to ensure there were no unforeseen impacts on groundwater levels.
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• There is likely to be a need for additional habitat areas, to mitigate for lost/damaged habitat and/or species impacts. Wider constraints within and adjacent to the sites also need detailed consideration, such as heritage/archaeology, landscape, and utilities such as gas/water mains and National Grid pylons. • There is the potential for background disturbance (from adjoining industrial areas and roads/rail) that could reduce the use of new habitat by birds. • Careful consideration of safety implications relating to attraction of potentially large flocks of birds adjacent to M49 motorway. • Potential sources or pathways of pollution need to be considered e.g. sediment, fertilizer, pesticides, herbicide run-off from adjoining agricultural land. At this stage, it is also important to highlight some habitat design principles and ways in which habitat creation opportunities could be maximised: • If possible, new wetlands should be located close to or be connected existing wetlands. This enables more rapid colonisation by locally characteristic plants and animals. • Ensure there is a source of clean water to supply the ponds, lakes and other freshwater wetland features. However, avoid linking lakes, ponds to existing inflowing watercourses, especially in areas of intensive agriculture (potential to pollute or introduce high level of nutrients and sediment). • Creating a mosaic of inter-connected habitats, including wet grassland (including scrapes), ponds, lakes and ditches provides greater biodiversity benefits than creating isolated habitats. • For surface water features, create a mosaic of very shallow and temporary features, as well as semi-permanent and permanent features. Provide different types of ponds, e.g. deep, shallow, varied etc. and ensure some of the features are off-line (i.e. not connected to ditches/rhines). For shallow ponds/lakes, maximise the draw-down zone around periphery, to provide plenty of marginal habitat. Some slopes around the water bodies should be very shallow, i.e. 1:50 slopes. • The design of new channels and surface water features should incorporate varied profiles and ensure that gradients of slopes vary as much as possible, in order to create micro-habitats along banks, margins and under water. Profiles should incorporate marginal shelves to maximise ecological potential. Introduce variety in the profile of both the drawdown zone and the rest of the water body. • Create low-level, muddy or gravel islands in ponds and lakes to provide refuge and roosting areas for birds. • Flexibility in design is important to enable the exact profiles of channel and wetland features to be directed on-site once channel has been excavated to the proposed design level. The location of wetland features should tie-in with areas of locally appropriate substrate and ground water conditions. Examples are provided below to demonstrate typical features that should be, where possible, incorporated into the design of new or regraded channels and wetland features. Typical scrape cross-section
Typical pond cross-section
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6.4 Water level management Hydrological management of rhines to develop the required habitats could be achieved through the penning of water (to raise ground water levels), and rhine widening to create muddy marginal berms (feeding areas for wading birds). Minimal excavation would be required for scrapes, as some of the existing ridge and furrow topography could be utilised. Ditches could be created to extend rhines to supply water to new scrapes. However, water level management via penning would need careful consideration and investigation, to ensure it did not compromise flood defence and ground water control function of rhines for agricultural land upstream of habitat areas. More localised water level management might be achieved by pumping water from retained rhines into new scrapes, or by capturing rainwater and holding it within units via a series of bunds. This would enable habitat areas to be managed on a field-by-field basis, but may require more ongoing management (and thus be less sustainable and costlier). Pumping would require continuous operation, maintenance and replacement, or an external power supply. Careful consideration and investigation would be required, to ensure it did not deny downstream landowners a supply of water. 6.5 Stakeholder comments The Internal Drainage Board indicated that as the area is used for pasture and arable farming and is therefore of relatively low strategic value. It was noted that the area of pasture and arable farming land is presently leased to four tenants, and they should be actively engaged to address their concerns and identify a solution that allows farming activities to be continued. Consultation with land owners and tenants will be critical for the identification of a preferred option. The stakeholders also expressed a preference for landowners or tenants to conduct maintenance of the habitat areas, but it was recognised that this may increase operational costs. Several specific considerations were also identified that will be important for the effective implementation of the habitat creation works. These considerations included: • A careful balance will be required between providing necessary habitats and payments for impacting the productivity of the land. • Scrapes need to consider the impacts that such works would have on the groundwater of the nearby areas, and the discharge along the rhine system. • Existing hedgerows and High Level Stewardship/Entry Level Stewardship agreements with landowners may influence the mitigation requirements for any works to create habitat areas. The possibility of using development land for habitat creation may be explored, however this would need to be balanced against the revenue lost from development. Loss of revenue from development may be mitigated through land swaps. It was broadly agreed that it is preferable to create habitat in as few areas as possible. One larger area of habitat will be more ecologically valuable than an equal area composed of smaller habitat areas. It was also agreed that a 100m buffer around habitat areas will not be required, with priority
41 given to establishing functional habitat. Determination of mitigation habitat delivered by an option should include peripheral habitats as well as specific wetlands. The potential benefits of linking the Hallen Marsh and Northwick sites to create wildlife corridors, largely through rhine widening, was also discussed. .
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7 Area 5 – Northwick Area 5, known as Northwick (Figure 11), lies directly north of the M4 motorway and south of the M48 motorway. It is bordered by the villages of Aust to the north and Northwick to the south. The main A403 road runs through the centre of the site. A number of public rights of way also cross the site. The north-west corner of the site rises steeply to Old Passage, whilst the majority of the rest of the site is characterised by predominantly low-lying ground, with some small areas of raised land within the site. It comprises approximately 250ha of semi-improved species poor grassland and arable land predominantly used for agriculture. Criss-crossing the site are a number of ditches (although they are not as extensive as at Hallen Marsh, Area 4). The land is also characterised by a network of hedgerows, of varying quality and density. Topographical data (LIDAR) suggests that there a number of relic channels and a number of major rhines crossing the site, some of which may form a flowing rhine network managed by the Internal Drainage Board (IDB).
Area 5 Northwick
Figure 11 - Area 5 Identified mitigation area This map is reproduced from Ordnance Survey © material by Halcrow on behalf of the ENVIRONMENT AGENCY with the permission of the Controller of Her Majesty’s Stationery Office. © Crown copyright. Unauthorised reproduction infringes Crown copyright and may lead to prosecution or civil proceedings. Licence Number: 100026380
Many of the habitat options, issues, constraints and opportunities discussed in this section are the same or very similar to those discussed in section 6 (Area 4, Hallen Marsh), but are repeated here for clarity. 7.1 Habitat creation requirements Area 5, Northwick, has been identified as having the potential to create areas of permanent standing water in the form of ponds and lakes with possible scrapes. Due to the low-lying nature of some the land, and the potential availability of water from major rhines that cross the site, there is also the potential in some areas to create large expanses of wet grassland habitat, with some ephemeral bodies of water (such as shallow scrapes that dry-up in summer). Pedestrian access at Northwick has also been highlighted as an aspiration. Table 7 provides a summary of the habitat requirements of the qualifying species and qualifying assemblage of birds that have been ‘scoped in’ for this project (Cresswell Associates, 2011).
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Table 7 - Summary of habitat requirements of wintering wildfowl and waders Species ‘scoped in’ Food type Habitats & specific requirements (Cresswell 2011) Gadwall Stems, leaves and Gravel pits, lakes, reservoirs and coastal wetlands in winter. seeds Breeding gadwalls found in the shallow vegetated edges of lakes and gravel pits. Shallow water - depth not exceeding
0.30m 4 Teal Seeds and aquatic Commonly found in sheltered wetlands. Shallow water - invertebrates depth not exceeding 0.20m Mallard Seeds, acorns and Wide range of wetland and open water habitats. Shallow berries, plants, water - depth not exceeding 0.35m Dabbling ducks insects and shellfish Shoveller Small insects and Open wetlands, such as wet grassland or marshes with plant matter sifted some emergent vegetation. Shallow water - depth not
from the water exceeding 0.30m
Pochard Plants and seeds, Open lakes and gravel pits. Deep water areas - at least 1m 5 snails, small fish and deep but also sloped sides to enable easy access and
insects egress. Tufted duck Molluscs, insects and Gravel pits, lakes, reservoirs. Deeper water - depth between
Divingducks some plants 0.35m and 5.0m Lapwing Worms and insects Found on wetlands with short vegetation. In winter they flock on pasture and ploughed fields. Curlew Worms, shellfish and Feed on mud or very soft ground, searching for worms and
shrimps other invertebrates with their long bills.
6 Common snipe Small insects, Edges of pools in well-vegetated wetlands including worms and
Waders insect larvae
A total of 250ha of land is under consideration for use in Area 5. However, there are a number of areas which are not considered physically suitable for creation of new wetland habitat, due to the topography. There are also a small number of areas of existing landscape and/or wildlife value (e.g. existing areas of woodland and thick hedgerows) where it would be preferable to retain the existing landscape. The actual area where habitat creation is therefore considered technically feasible is 227ha. A Phase 1 habitat survey has been undertaken (reference the CH2M report when completed) which identifies areas of particular ecological value that should be retained, or could be incorporated within a new wetland habitat landscape. Target habitats considered during this high-level appraisal for Area 5 include both wet grassland and open water habitat (ponds/lakes). The importance of wet grassland habitat for wintering and breeding wading birds, such as lapwing, curlew and common snipe, is summarised in Section 6.1. Open water habitats, such as ponds, lakes and shallow scrapes, provide vital refuge areas and feeding grounds for a number of wildfowl, including the dabbling ducks and diving ducks listed in Table 7 above. Ponds (<2ha) and lakes may be permanently or seasonally flooded, and in addition to providing habitat for wildfowl, they offer
4 Dabbling ducks search for food sifting through surface water, up-ending in the shallow reaches and often dabbling in the mud. Content with shallower and more restricted bodies of water than diving ducks. Generally feed in and around aquatic and marginal vegetation. Flooding releases seeds and invertebrates from vegetation, so is an important requirement for this species group. Dabbling ducks benefit from a large edge/surface area ratio on flooded areas (i.e. lots of emergent vegetation - seed sources).
5 Diving ducks dive and feed at the bottom of the water, often many feet below the surface. Require deep water (>2m) with high densities of invertebrates in sediment.
6 Waders – overwintering waders require soft, damp soil and high water tables. Winter flooding to create islands of grassland and shallow open water suitable for roosting. 44 an invaluable network of semi-natural habitat within protected sites, urban areas and the wider countryside. Ponds in agricultural settings are often adversely affected by run off from intensive farming methods and damage from poaching and grazing by livestock, particularly cattle. Buffers of semi-natural terrestrial habitat and fencing around ponds can serve to safeguard and enhance the nature conservation value, although heavy shading can greatly reduce the species diversity of ponds. Ponds will undergo natural succession to marsh and scrub over-time and therefore occasional desilting may be required, but the maintenance of a wide range of successional is important in maintaining the overall species diversity of the habitat. A maximum depth of 1m is normally sufficient for small ponds and 1.5 to 2m for larger ponds or lakes. Maximising the area of shallow water (<0.4m deep) around the pond edge for marginal and aquatic vegetation and incorporating as much physical diversity as possible e.g. by varying bank slope and water depth and wavy edge will contribute to the diverse habitat provided by ponds and lakes. If possible, construct several ponds/lakes close together, with varying sizes, depths and permanence. 7.2 Habitat creation process Many of the fundamental habitat delivery aims, opportunities and constraints are the same as those at Hallen Marsh. While habitat mitigation works at Northwick will include the provision of open water space, the high level options for achieving habitat mitigation are the same. Alternative locations for the provision of these mitigation requirements have been previously explored, eliminating some other sites. The opportunity to provide habitat mitigation areas that will support species affected by works in the ASEA are therefore limited. Subject to landowner negotiations and other constraints, habitat creation may be maximised throughout the whole of Area 5 or the maximum available portion of the Area through the creation of connected habitats. Parts of the site could be hydrologically and physically connected through, for example, site-wide management of the rhines and removal of some of the hedgerows. This would enable the creation of an open, diverse mosaic of new wetland habitat (wet grassland, scrapes, ponds, lakes) together with retention of existing ecologically diverse features of the site, such as woodland areas, mature, dense hedgerows and existing ponds. If a smaller area of total land is available it may require the creation of specific habitat ‘units’ which focus on creating specific habitats, e.g. one area of wet grassland and a separate area of open water habitat. These habitat units could then be managed independently of adjacent fields or units, without consideration of connectivity with existing or other new habitat areas. This could provide more flexibility in terms of negotiation with landowners and could also enable site specific hydrological requirements to be accommodated. Agricultural management on a field-by-field basis would be easier to achieve, but regardless of the approach taken the overall aim of the work will be to deliver the maximum area of habitat mitigation as possible within the constraints posed by Area 4. 7.3 Issues, Risks, Constraints and Opportunities There are a number potential issues, constraints and risks that will need further consideration during the more detailed option appraisal and outline design stages of the project. Many of these are the same as discussed for Area 4, Hallen Marsh, but are repeated here for clarity. These include: • Areas suitable for the creation of required habitats will be affected by the ground conditions within Northwick. The soil characteristics and proximity to existing rhines will influence whether the habitat mitigation scheme is viable. More substantial works are anticipated at Northwick, with larger scrapes to create freshwater habitats. The drainage of such areas will be heavily influenced by the ground conditions. • Ensuring changes to the landscape and habitats within the mitigation area is acceptable to land users. The existing pasture and agricultural use of Northwick will be retained after the mitigation
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works, however the changes introduced to the landscape are likely to affect productivity of the area. It will be critical to reach agreement with tenancy owners over use of the land, potentially provide compensation for reduced productivity, or land purchase if required. • The ownership and maintenance of any structures within the mitigation areas will also require agreement. Maintenance by landowners or tenants may avoid the need for access by third parties, however it may incur additional costs. • There may be some resistance or a presumption against penning of water levels in the rhines, due to the possibility of raising water levels upstream and causing capacity issues in these locations. Use of in-channel sluice or weir structures to pen water levels may also require significant mitigation to comply with the Eel Regulations. • Scrapes and ponds/lakes would need to be carefully designed, to ensure there were no unforeseen impacts on groundwater levels. • There is likely to be a need for additional habitat areas, to mitigate for lost/damaged habitat and/or species impacts. Wider constraints within and adjacent to the sites also need detailed consideration, such as heritage/archaeology, landscape, and utilities such as gas/water mains and National Grid pylons. • Careful consideration of safety implications relating to attraction of potentially large flocks of birds adjacent to M4 and M48 motorways. • Potential sources or pathways of pollution need to be considered e.g. sediment, fertilizer, pesticides, herbicide run-off from adjoining agricultural land. At this stage, it is also important to highlight some habitat design principles and ways in which habitat creation opportunities could be maximised: • If possible, new wetlands should be located close to or be connected existing wetlands. This enables more rapid colonisation by locally characteristic plants and animals. • Ensure there is a source of clean water to supply the ponds, lakes and other freshwater wetland features. However, avoid linking lakes, ponds to existing inflowing watercourses, especially in areas of intensive agriculture (potential to pollute or introduce high level of nutrients and sediment). • Creating a mosaic of inter-connected habitats, including areas of wet grassland (including scrapes), ponds, lakes and ditches provides greater biodiversity benefits than creating isolated habitats. • For surface water features, create a mosaic of very shallow and temporary features, as well as semi-permanent and permanent features. Provide different types of ponds, e.g. deep, shallow, varied etc. and ensure some of the features are off-line (i.e. not connected to ditches/rhines). For shallow ponds/lakes, maximise the draw-down zone around periphery, to provide plenty of marginal habitat. Some slopes around the water bodies should be very shallow, i.e. 1:50 slopes. • The design of new channels and surface water features should incorporate varied profiles and ensure that gradients of slopes vary as much as possible, in order to create micro-habitats along banks, margins and under water. Profiles should incorporate marginal shelves to maximise ecological potential. Introduce variety in the profile of both the drawdown zone and the rest of the water body. • Create low-level, muddy or gravel islands in ponds and lakes to provide refuge and roosting areas for birds. • Flexibility in design is important to enable the exact profiles of channel and wetland features to be directed on-site once channel has been excavated to the proposed design level. The location of wetland features should tie-in with areas of locally appropriate substrate and ground water conditions.
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Examples are provided below to demonstrate typical features that should be, where possible, incorporated into the design of new or regraded channels and wetland features. Typical scrape cross-section
Typical pond cross-section
7.4 Water level management Hydrological management of rhines to develop the required habitats could be achieved through the penning of water (to raise ground water levels), and rhine widening to create muddy marginal berms (feeding areas for wading birds). Minimal excavation would be required for scrapes, as some of the existing ridge and furrow topography could be utilised. Ditches could be created to extend rhines to supply water to new scrapes. However, water level management via penning would need careful consideration and investigation, to ensure it did not compromise flood defence and ground water control function of rhines for agricultural land upstream of habitat areas. More localised water level management might be achieved by pumping water from retained rhines into new scrapes, or by capturing rainwater and holding it within units via a series of bunds. This would enable habitat areas to be managed on a field-by-field basis, but may require more ongoing management (and thus be less sustainable and costlier). Pumping would require continuous operation, maintenance and replacement, or an external power supply. Careful consideration and investigation would be required, to ensure it did not deny downstream landowners a supply of water. 7.5 Stakeholder comments Preliminary feedback from some stakeholder organisations highlighted the length of the process completed to date in identifying appropriate areas for habitat creation. Five other sites were discounted from delivering habitat mitigation prior to Northwick, therefore alternative sites are unlikely to be readily identified. The habitat creation scheme is required to allow the future development of the ASEA. A larger partnership may provide the drive and direction necessary to implement the habitat creation works, although a Vision may need to be developed to draw stakeholders together. Such a Vision may include tourism benefits as well as direct ecological improvements It was agreed that low intervention and maintenance options are preferred at Northwick. Such an approach could capitalise on the natural topography, with higher land areas providing water supply for grassland in the lower areas to develop wetland habitat. The existing rhines and outfall
47 structures at the coast have known siltation issues making penning an unattractive option, although recent upgrade works has mitigated this at Aust. It was also stated by stakeholders that a Water Framework Directive assessment may identify a benefit in using higher land to store water, reducing soil erosion and runoff, and improving the rhine system. A potential benefit was identified from early engagement with local landowners to allow more effective wildlife and species protection and development. Past conversations with landowners has indicated that this is an area of interest, and such activities may therefore have strong support.
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8 Option Assessment 8.1 Assessment criteria The appraisal of the short-list options will need to consider a wide range of criteria to provide the comprehensive assessment necessary for business case approval. The following section outlines a number of criteria that are recommended for the option assessment process, with a brief explanation of what the assessment will consider. Aligned with Severn Estuary Flood Risk Management Strategy The Severn Estuary Flood Risk Management Strategy states the preferred option for managing the coastal areas within the study area. Aligning with the strategy will ensure the works within the Avonmouth to Aust coastal area are managed in the most sustainable manner, and in accordance with the Shoreline Management Plan (SMP2). Adaptive approach for flood defence Adaptive management of flood risk offers significant benefits for the project through efficiencies in cost and material use achieved by greater understanding of the future flood risk. Periodic review of the climate change impacts will allow upgrade of flood defences; however some locations or flood defence structures are more suited to implementing further works for crest elevation. Constructing flood defences close to the railway line or incorporating highway structures within the flood defence will introduce significant impacts on local transport. Reduction in flood risk The ability of a flood defence to provide the necessary standard of protection in a reliable and consistent manner is an essential consideration for the effective implementation for the options being considered. The inability of a flood defence to operate under all conditions could lead to flooding of the Enterprise Area and the adjacent residential and transport developments. The improvement of flood protection to some locations at the price of increased flood risk to other areas is considered unacceptable. Ecological opportunities/impacts The influence that flood defence works have on designated habitats (SAC, SPA, SSSI, etc.) within the study area and nearby locations will be assessed to ensure that the potential impacts are understood and adequate mitigation can be introduced if necessary. The following designations may have an influence on a scheme to improve the standard of flood protection at the ASEA: • Severn Estuary SAC • Severn Estuary Ramsar site • Severn Estuary SSSI • Aust Cliffs SSSI • Lawrence Western Moor Local Nature Reserve • Forest of Avon Community Forest Construction or modification of flood defences could potentially have a detrimental effect on geomorphology and ecosystem performance driven by changes to hydrodynamics, water chemistry and/or turbidity. Each of the designated areas may be affected during construction, with the relative impact determined by the size of the proposed works and the distance of works from the environmental receptor. An assessment of the potential consequences of construction will be examined in a draft Habitats Regulations Assessment (HRA), which will be prepared in accordance
49 with the requirements of the Conservation of Habitats and Species Regulations 2010 (as amended). This will be revised as necessary during the detailed design and in parallel with the EIA process Preliminary high level assessment of the potential ecological risks will be undertaken based on existing baseline data, where the initial survey work and consultation has provided a suitable basis for commencing the identification of potential ecological risks. Protected species surveys, specifically for otter, water vole, badger, great crested newt and bats, are being undertaken as the scheme progresses to inform mitigation and enhancement measures as appropriate. Historic environment opportunities/impact Known historic environmental assets within the study area include a heavy anti-aircraft battery, designated as a Scheduled Monument a short distance south of Chittening at the coast, as well as the ‘Mere Bank and flanking ditches’ Scheduled Monument which is located further inland at Avonmouth. There are also a large number of listed buildings throughout the study area along with a number of National Character Areas. Protection of historic environmental assets during construction may result in additional cost and time delays to the project. The influence that flood defence works might have on statutory and non- statutory heritage designations will be assessed to ensure that the flood defence options avoid impacts on assets or include adequate mitigation if required. Geomorphological/hydromorphological impact The Severn Estuary is a dynamic environment with the interplay between waves, tides and land drainage and the landform, or geomorphology, is a reflection of that. The estuary is a high turbidity low energy environment but there is also a wealth of sediments such as sands and gravels. In areas like Aust and Severn Beach the outcropping rock has a controlling effect on the form of the estuary. A quantitative assessment of the potential impacts on the geomorphology has been carried out. Each of the proposed options has been assessed in order to understand its effect on the stability of the current form of the estuary, the influence on any sediment transport routes, the potential to lead to impacts on regions colonised by important habitats. Where it is possible to provide a ‘soft defence’ or encourage coastal realignment this will be considered as an opportunity to allow for the natural evolution of the estuary and associated habitats. The effect of the proposed works has been considered on a range of scales, from the frontage itself, the surrounding area, and the macro scale of the whole estuary. Any potential changes need to be understood against a backdrop of a dynamic estuarine environment and the changes continuing due to direct anthropogenic change such as dredging, construction of defences, and major projects such as Hinkley Point and the proposed Severn Estuary tidal power project. Climate change, with the potential for increased storminess and more energetic waves will also have a considerable influence in the future. Geotechnical and geo-environmental risk Assessment of the geotechnical and geo-environmental risk covers two broad topics. The geotechnical assessment examines the suitability of ground conditions for the construction or modification of flood defence works, and the level of confidence in the ground information collected. This is largely determined by the amount of previous ground information collected along the defence alignments. The geo-environmental risk of each potential option is assessed by the potential release of contaminants from waste disposal and land fill sites. The study area includes several such sites, particularly the former ICI waste disposal site south of Severn Beach.
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Land take and land use change The potential land take of a defence or habitat creation scheme is considered an important factor in the options appraisal and development process. Adoption of structures with a large footprints may encounter difficulties due to the existing development and transportation constraints as well as the potential environmental impact and associated compensation requirements. Further, the introduction of structures with a large land take may result in a change of land use in some areas, particularly in Areas 4 and 5 where potential loss of agricultural land may be necessary to accommodate new structures. Landscape and visual amenity Assessment of the impact of the proposed defence alignment and structure on the visual amenity and landscape character for a variety of receptors, including nearby settlements and public rights of way. Changes to the landscape character may be mitigated in part through choice of construction materials at the design stage, or additional features such as vegetated embankments. It is expected that the most significant impacts will occur where new structures are introduced to previously undeveloped sections of the study area, or where a new structure would create a significant change from the existing character of the area. Recreation and Amenity The assessment of recreation and amenity use impact is assessed by consideration of the influence of defence alignments on the access to Public Rights of Way, bird watching locations and facilities, and other recreational activities within the study area. Public access is presently provided along much of the coast, while the intertidal and other habitat areas provide recreation use for both the local population and tourists. Direct impact to the public footpaths or recreational use of the area may create complications in obtaining approval for the project at a later stage, and may require potential compensatory measures. Health and Safety Consideration of the Health and Safety implications of defence options is a statutory requirement for all design work, and there are some specific areas of concern for the ASEA that may create potential problems. • The proximity of the defences to power generation and transmission infrastructure may complicate construction; • The proximity of the public, including residential housing, existing commercial and industrial activities, and transport routes; • Retaining the ability to safely maintain the second Severn crossing, which is presently achieved through a railed system beneath the bridge. The maintenance equipment passes very close to the flood defence in the area, and changes to these structures may create additional health and safety risks for maintenance staff. • Proximity to railways and highways
Buildability The buildability of a flood defence is dictated by the specific location and type of flood defence under consideration. Construction within close proximity to important services and infrastructure will complicate construction and increase the programme and cost of the works. Work within the Severn estuary will place restrictions on the timing and methodology of construction activities due to
51 the large tidal range, but may also be restricted by the seasonal sensitivity of protected species and habitat areas. Access can impose constraints on how construction is undertaken, with preference for access routes that use less congested parts of the transport network or impose less impact on existing properties and buildings in close proximity to access routes. Similarly, construction which involves significant heavy civils works in close proximity to existing properties and buildings, or main railways, roads, and bridges will be constrained by the need for safe working zones and minimising the impact from noise, vibration, dust etc. Sustainability The determination of whether an option is sustainable considers a variety of perspectives. Effective use of land, whole life power demands, requirement to regularly deployment of operations team for effective management all contribute to the long term sustainability of structures. Whole-life costs Comprises outline estimates of capital cost based on an indicative estimate of the length, height and material to be used for a specific alignment. Only indicative estimates can be made at this point as identification of the specific engineering solutions to be adopted requires further investigation and assessment. This criterion also includes outline estimates of maintenance costs based on broad understanding of the potential challenges facing each alignment throughout the design life of the project. 8.2 Recommended option alignments Fuller details of the High level option assessment are included in Appendix A. The following sections define the recommended alignment option for each of the five Areas within the wider study area, pending further discussions with stakeholders in September 2016. 8.2.1 Area 1 It is recommended that defences are largely constructed along the existing alignment to capitalise on the flood defence structures already in place while maximising the area and number of properties afforded flood defence. This will ensure the construction of a sustainable flood defence that uses less materials than a new construction and will require lower capital costs. The existing outfalls within Area 1 can be retained at their existing location, requiring less capital construction works and lower costs. Reconstruction of the existing defences will protect the limited number of assets within Area 1 and will prevent inundation to adjacent locations. This includes the small number of settlements as well as the transport infrastructure of the A403. The area considered for freshwater habitat mitigation will be fully protected by the existing alignment and will allow greater flexibility in the provision of compensation for future industrial development. Improvement of the existing embankment from Severn Beach to Aust may be achieved in a number of ways, and identification of the preferred option will require further analysis. Potentially viable options include: • Increase to the crest elevation and width of the existing earth embankment; • Increase to the crest and width of the existing embankment with armouring of the defence and protection at the toe to protect against erosion; and • Increases to the crest elevation of the embankment through the introduction of a flood wall at the back of the embankment crest. The advantages of continued defence along the coastal alignment are wide reaching, covering engineering, environmental and social characteristics. Flood defences along the existing alignment 52 will protect all known and unknown historic environment assets, including the existing embankment structure. Higher elevation defences will create visual impact for recreational users and the small number of residents, and public access along the defence might also be impacted. These impacts are unlikely to be significant due to the small increase in flood defences. Elevation of the defences that form the existing Severn Beach tidal defence scheme will be achieved through modification to the earth embankments and concrete structures. Retaining the existing alignment also has a number of disadvantages. Increases in water level in the Severn Estuary will lead to coastal squeeze throughout Area 1 as the intertidal area narrows. This will permit larger wave action close to the coast, leading to erosion of the defence structure requiring additional materials to resist the erosion and higher associated costs. Table 8 outlines the objectives which would be met by the recommended alignment for shortlist appraisal. Table 8 Objectives met by recommended coastal alignment option for Area 1.
Objective Comment Reduce the cost of flood damage The elevated standard of protection created by the new flood defences will reduce the frequency and extent of future flood events, reducing damages. Reduce the risk of flooding to infrastructure, Elevated defences will protect areas with planning utilities and businesses; permission for future development in the adjacent Area 3. Enable delivery of the Outline Development Protection of the areas identified for future Strategy development within the ASEA Reduce the risk of flooding to properties and The increased standard of protection will safeguard life properties currently at risk. Take account of risks of climate change The crest level of the defences will be established to provide the necessary standard of protection with account of climate change. This may be implemented in an adaptive manner. Ensure the scheme is deliverable (in The likely defence techniques are clearly understood, engineering terms) with broad experience of successful delivery of similar projects throughout the UK. Ensure the scheme is capable of achieving The alignment avoids impacts to environmentally required consents designated areas and takes advantage of existing structures to avoid the
If improvement of the existing defences is not possible due to environmental impacts of construction, a primary-secondary defence line system might be adopted. This would comprise maintenance works of the existing structures to act as the primary defence, and the construction of flood embankments further inland to control flooding to properties and infrastructure. 8.2.2 Area 2 It is recommended that defences are largely constructed along the existing alignment to capitalise on the existing flood defence structure while maximising the area and number of properties afforded flood defence. Works along the Severn Estuary coast will need to align with Bristol Ports Company’s long term plans for the proposed DSCU, which might form part of the primary flood defence for Area 2. The Port has indicated support for maintaining and improving the coastal defences in Area 2.
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The flood defence is likely to involve modification of the existing structures, with increased elevation through minor modification. On the right bank of the River Avon the crest level of the earth embankment will be increased through changes to the earth embankment or the addition of a small flood wall. It may be necessary to armour the existing embankment to ensure that the embankment is not damaged by more regular inundation and wave action in the future. The tidal gates will be modified or replaced to increase the crest level of the structure and improve the SoP provided. It will be important to ensure that a consistent SoP will be provided by the flood defences within the port area and the adjacent flood defences along the River Avon and Severn estuary. Any changes to the flood defences will require discussion with Bristol Ports Company to ensure the needs of the docks and the needs for flood defences can be delivered together. The short and narrow flood wall to the north of Avonmouth docks area will likely be replaced by a new and more significant wall. This will ensure that the defence will effectively resist the additional flood risk created by higher water levels and will not negatively impact the nearby infrastructure. Flood defences within Area 2 will provide maximum benefits through protection of all assets within Area 2, and will prevent flood inundation of adjacent areas. The potential for partnership funding may be possible through the protection of transport and industrial facilities close to the coast. Locating defences within the Avonmouth docks will potentially create complications for accessing the flood defences assets for inspection and maintenance tasks. Table 9 outlines the objectives which would be met by the recommended alignment for shortlist appraisal. Table 9 Objectives met by recommended option for Area 2
Objective Comment Reduce the cost of flood damage Elevated flood defences along the coast will improve the standard of protection and reduce flood damages Reduce the risk of flooding to infrastructure, Elevated defences will protect the existing transport utilities and businesses and industrial infrastructure, including the Avonmouth dock facilities Enable delivery of the Outline Development Aligning future defences along the existing defence Strategy alignment will ensure that the full ASEA is protected from flooding, and will allow the development strategy to be realised Reduce the risk of flooding to properties and Elevated defences will protect the existing residential life development at Avonmouth Take account of risks of climate change Introduction of elevated flood defences will account for the increased risk of flooding expected from sea level rise
8.2.3 Area 3 It is recommended that defences are largely constructed along the existing alignment to capitalise on the existing flood defence structure while maximising the area and number of properties afforded flood defence. The defences in the southern section of Area 3 will likely involve the raising of an existing embankment seaward of the railway line, with works at the toe of the structure to protect against erosion. The defences at the former ICI waste disposal site will likely involve the introduction of formal flood and coastal erosion protection around the existing area of high ground. This will ensure that contaminants will not be released into the environmentally designated Severn Estuary area. Where possible modifications to defences will be sought on the landward side of existing structures, however temporary and permanent impacts are expected for improvements on the existing 54 alignment. Provision of compensatory habitat will be required if these impacts are realised for the preferred defence option, although impacts through to 2030 are covered by the compensatory schemes at Steart and Alvington. Flood protection to the whole Hallen Marsh area will allow the maximum freshwater habitat mitigation area to be delivered within Area 4. Construction within close proximity to the railway line and the A403 will add significant health and safety and logistic difficulties. Combined with tidal working, the programme for delivering the flood defences in this area may be longer than other areas with fewer constraints. Effective collaboration with partner organisation will be necessary to allow safe and effective delivery. It is recommended that any necessary improvements to the surface drainage of the ASEA and discharge through coastal outfalls is delivered through temporary storage areas landward of the coastal defences. Such an approach will allow for storage of water when outfalls become tide- locked, and a more detailed technical assessment will establish the volume of temporary storage required. Identification of suitable locations will dictate whether this option is possible, however it potentially addresses the flood risk without introducing significant health and safety concerns or substantial capital expenditure. It also offers additional potential environmental benefit. Table 10 outlines the objectives which would be met by the recommended alignment for shortlist appraisal. Table 10 Objectives met by preferred option for Area 3
Objective Comment Reduce the cost of flood damage Elevated flood defences along the coast will improve the standard of protection and reduce flood damages. Improved management of surface flooding behind the defences will reduce flood damages. Reduce the risk of flooding to infrastructure, Elevated defences will protect the existing transport utilities and businesses and industrial infrastructure, including the railway line, A403 and industrial facilities at Chittening Enable delivery of the Outline Development Aligning future defences along the existing defence Strategy; and alignment will ensure that the full ASEA is protected from flooding, and will allow the development strategy to be realised Improve ecological opportunities Protection of areas inland will ensure the full area at Hallen Marsh can be used to create freshwater habitat mitigation. Take account of risks of climate change Introduction of elevated flood defences will account for the increased risk of flooding expected from sea level rise Ensure the scheme is deliverable (in Flood defences along the existing alignment will engineering terms) ensure the preferred policy of ‘Hold the line’ will be pursued. Increasing the ability to handle surface drainage will also help to address potential increases in rainfall.
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8.2.4 Area 4 In order to achieve the overall aim of providing sufficient habitat mitigation for the ASEA, whilst accounting for uncertainty regarding the quality of the wetlands provided, the project should seek to maximise the total area of habitat mitigation required for the enterprise area. The potential benefits of this are that: • It will maximise the total area of habitat mitigation (i.e. provide more than the minimum 85ha area), which will ‘future proof’ commercial development within the enterprise area, allowing economic growth in the enterprise area to be extended beyond current plans. • It will provide a more sustainable scheme, which can be constructed and managed more holistically than development of separate, potentially isolated habitat units. • It will deliver more ecologically diverse and functional habitat, which will be able to accommodate existing valued landscape, ecological and heritage features within a wider mosaic of habitats. • Enable the rhine systems and associated ditches to be managed holistically, whilst taking into account upstream and downstream constraints and managing flood risk in a more holistic manner. Successful delivery of the habitat relies on further detailed investigations and modelling of technical solutions, as well as comprehensive landowner and wider stakeholder negotiations. Potential solutions for the management of habitat areas are included in Appendix B. 8.2.5 Area 5 As per Area 4 above, the project should seek to maximise the area of land available for habitat. There is the potential to develop this area into a more managed nature-reserve type area, which would require development of a wider partnership to enable ongoing operation. The facility could incorporate existing features, such as public rights of way, landscape and heritage features to provide additional benefits for amenity, education and tourism, with potential economic benefits such a site could bring. Successful delivery of such an option relies on further detailed investigations and modelling of technical solutions, as well as comprehensive landowner and wider stakeholder negotiations
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9 References AMion Consulting Limited, 2012. Outline Development Strategy. Final Report prepared by AMion Consulting Limited. April 2012, pp.98. Atkins, 2006. Avonmouth to Aust Tidal Defence Scheme. Stage 1 Interim Report. Part 3: Coastal Inundation Modelling. Report prepared by Atkins. November 2006. Atkins, 2013. Avonmouth-Severnside Flood Management Optioneering. Final Report prepared by Atkins for Avonmouth/Severnside Development Board: Flood Risk Sub Group. November 2013, pp.75. Bristol City Council and South Gloucestershire Council, 2012, Avonmouth and Severnside Integrated Development, Infrastructure and Flood Risk Management Study. Final report produced for South West Regional Development Agency, Bristol City Council and South Gloucestershire Council. April 2012, pp.114. Bristol City Council, South Gloucester Council and Lower Severn Drainage Board, 2011. Strategic Flood Risk Assessment Avonmouth / Severnside. Final Report produced by Bristol City Council, South Gloucestershire Council and Lower Severn Drainage Board. February 2011, pp.352. Cresswell Associates, 2011. Severnside and Avonmouth Wetland Habitat Project – Stage 2 Review of Constent at Severnside and Avonmouth Imapct Assessment. Final report produced for South Gloucestershire Council, Bristol City Council and Natural England. December 2011. Environment Agency, 2006. Tidal Severn Flood Risk Management Strategy. Final report produced by the Environment Agency. March 2006. Environment Agency, 2013. Severn Estuary Flood Risk Management Strategy – Baseline Assessment. Final Report produced by Atkins Limited for the Environment Agency. 2013, pp. 172. Severn Estuary Coastal Group, 2000. Severn Estuary Shoreline Management Plan (SMP). Executive Summary report prepared by Severn Estuary Coastal Group. December 2000, pp.157. UK Climate Impacts Programme. UKCP09. Available online at: http://ukclimateprojections.defra.gov.uk/
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Appendix A: High level option assessment matrix
Matrix Legend: Minor or no substantive impact Moderate impact High impact Severe impact which eliminates option
Area Long list Alignment
option
(to enable (toenable
-
Outline
cal and cal geo
SevernEstuary Flood Risk
Alignedwith Development Strategy(protects thefor ASEA future development) and Management Strategy approach Adaptive for flood defence Reductionin flood risk protectionto ofASEA a 1:200SoP withCC for 60 years) opportunities/ Ecological impacts environment Historic opportunities/impact Geomorphological/ hydromorphologicalimpact Geotechni environmentalrisk Landtake and land changeuse Landscapeand amenity visual Recreationand amenity and Health safety Buildability Sustainability Wholelife costs All Do Existing Does not support No changes to the Unacceptable No negative Reducing standard Failure of the Lower standards of The flood defence Preserving existing Where currently Residual Health and This option has no This option has no Do nothing has no Nothing alignment ‘Hold the line’ flood defence are standard of ecological impacts of protection over existing defences protection offered approach will not defence levels will provided, public Safety risk for the buildability issues buildability issues capital or intended. protection will be area associated time will increase will be expected by flood and coastal require an increase avoid visual impact, access in the short- public will be a as minimal as minimal maintenance cost
afforded to assets. with capital or flood risk of known over time, allowing erosion structures in structure however the term will be concern due to the intervention intervention implications. maintenance and unknown more natural throughout the footprint. Lower landscape retained, however deterioration of the works. historic evolution of study area will lead standard of character will access to the existing flood environment undeveloped to the erosion of protection to areas change over time. coastal areas will defences. assets. coastal areas and existing industrial, behind the defence be compromised in the potential land fill or waste will reduce the the medium and development of disposal sites. suitability of short term as the new bays. development and standard of may require protection declines. changes to land use. All Do Existing Does not support No changes to the Unacceptable No increase in Reducing standard Maintenance of Lower standards of The flood defence Preserving existing Maintenance of the Maintenance of the Moderate. Poor sustainability Moderate whole Minimum alignment ‘Hold the line’ flood defence are standard of footprint of flood of protection over existing structures protection offered approach will be defence levels will existing structures existing flood Piecemeal as regular life costs are intended. protection will be defences, however time will increase will lead to coastal by flood and coastal unlikely to require avoid visual impact. will, where defences will require interventions likely maintenance works expected as
afforded to assets. maintenance of flood risk of known squeeze in areas erosion structures an increase in Landscape currently provided, works close to the to be ad-hoc and will be required. piecemeal existing structures and unknown with intertidal throughout the structure footprint. character may retain public access Severn estuary, and not strategically interventions will will lead to coastal historic habitat. study area will lead Lower standard of change over time, to the coast, may require tidal aligned be required to squeeze in areas environment to the erosion of protection to areas however the though this will working. address with intertidal assets. existing industrial, behind the defence decline over time intermittent habitat. land fill or waste will reduce the as the standard of damage. disposal sites. suitability of protection declines development and over time. may require changes to land use. 1 Improve Coastal Defence Supports preferred It is possible to The existing Development on This Area contains a Holding the flood The existing Widening of the Limited and Improvements The existing The increase in Flood defences The cost of (coastal) – Existing policy of ‘Hold the improve the alignment protects the seaward side of number of listed defences along the alignment will flood defence localised changes along the existing alignment offers crest elevation can along the existing improving the flood alignment line’ standard of all assets within the existing buildings and has existing alignment protect waste footprint on the to landscape defence alignment relatively minor risk be readily achieved alignment will take defence along the protection over Area 1, providing defences would high archaeological will result in disposal sites in landward face of character and will protect the from a health and through increasing advantage of the existing alignment time to address the the maximum cause both potential for narrowing of the Area 1 from the existing visual amenity as public access along safety perspective. the crest elevation existing structure, may be relatively elevated risk of available benefit permanent and unknown assets. intertidal area becoming exposed, embankment will status quo the coast and will The existing of the existing making efficient high depending on flooding created by for the project. temporary impacts The existing seaward of the ensuring that result in the loss of essentially increase the flood alignment does not embankment or use of land areas. the erosion SLR. Incremental on the intertidal alignment will offer defences. The wide contaminants do a small amount of preserved. Seaward protection for the have service introducing a short The updated flood protection required increase in the area. This might be flood protection for area of saltmarsh not impact the agricultural land. views from behind bird watching transmission flood wall. The defence is unlikely on the seaward crest elevation of avoided through both known and south of Aust may adjacent This increase in the defence may be facility in the south infrastructure, and close proximity of to require face of the the existing use of steel sheet unknown assets. transition to environmentally footprint size is interrupted but of the Area. would not involve important intertidal deployment of an structure. embankment can pile cut-off. The The flood mudflat, and will designated areas. much less than the properties are fairly works in close habitat and Operations team to Introduction of be adopted. area at Northwick embankment along expose the existing This alignment footprint required limited in Area 1, proximity to any potentially soft provide the rock protection intended for much of Area 1 is a defences line to offers greater for a new defence resulting in popular traffic routes ground may necessary standard along throughout freshwater habitat historic feature that more energetic confidence in the further inland. relatively few or railway lines. The complicate of protection. Area 1 and toe mitigation will be may require wave conditions as ground conditions receptors. Views northern section of construction of protection to the protected. mitigation to avoid depths increase. as more historic GI from Severn Way Area 1 crosses New more significant embankment will damage. data is available may be slightly Passage Road, and civil works. require substantial Temporary impacts along the existing elevated but runs parallel with this capital costs. Steel on breeding and defences. preserved by the highway towards Aust sheet piling may over-wintering bird retained route Cliffs, however this is result in lower assemblages along the top of the a low traffic volume capital costs, associated with the defence. road that can be although may Severn Estuary. effectively managed require additional Water quality will to reduce health and maintenance. need protection on safety concerns. The the seaward side of residual health and the embankment safety risk to the during public will be development. relatively low. Set Back Does not support The existing No flood protection No direct impact is Realignment of the Realignment The inland location Direct land take for Minimal Realignment of the Realignment works A relatively short The alignment The capital cost of Defence 1 – ‘Hold the line’ defences can be within Area 1 will expected on the flood defences will further inland will of the defence will flood defences will construction, defences will result adjacent to the M4 section of flood adjacent to the M4 constructing the Realigned close retained along the result in the existing intertidal offer no long term allow natural not afford be small. therefore minimal in the future loss of will involve defence will be is shorter than the relatively short to M4 existing alignment unacceptable area. Brackish defence for historic evolution of the protection to waste Substantial change short-term effects the coastal public construction works in constructed other alignments, length of until flood risk to future flood risk to habitat will form environment coast. The area disposal sites within to the landscape on landscape or access route. The close proximity to a adjacent to the M4. requiring less embankment is assets in adjacent the small behind the existing assets, exposing close to Severn Area 1, potentially character of Area 1 amenity. In the bird watching major road network, The defence would material. likely to be
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Area 3 becomes settlements of defences as sea them to more Beach may allowing can be expected, long-term sea level facility will be although the specific likely be achieved Deployment of an relatively small, unacceptable. Northwick and levels rise and regular inundation transition from contaminants to be with development rise is likely to exposed to greater alignment may through a simple Operations team while maintenance Phased Redwick, as well as inundation and damage. terrestrial habitat released into the of brackish habitat restrict public flood risk. mitigate any risk from embankment with during extreme costs are expected construction of the the area intended becomes more to estuarine. Initial adjacent areas close to the access and affect high speed traffic. The armouring and events is unlikely to to be limited. new defence can for habitat frequent. This will narrowing of the designated areas. coast. Agricultural visual amenity proximity to Redwick sheet-pile cut-off as be required. then be completed mitigation at compromise the intertidal area The ground output within this along Severn Way will require more required. Access to to improve the Northwick. area at Northwick across much of conditions are not Area may decline as and result in long effective traffic the site is good. standard of intended for Area 1 will be as well defined the environment term landscape control than protection. freshwater habitat expected, however along set back becomes more character change. improvements along mitigation. breaching of the defence alignment saline. the existing defence existing defences 1. alignment. may be required. There is potential for a new bay to open up between the footings of the First and Second Severn crossings. A landward realignment would allow for the development of a stable coastal form to evolve over time and the creation of the maximum potential habitat. Set Back Does not support Modification of the Unacceptable No direct impact on Realignment of the Realignment The inland location Direct land take for Minimal Realignment of the Realignment works Introduction of a The construction of The cost of works Defence 2– ‘Hold the line’ flood defence future flood risk to the existing flood defences will further inland will of the defence will flood defences will construction, defences will result adjacent to the A403 structure adjacent a new structure along the low-lying Realigned close through changes to a large number of intertidal area. The defend some allow natural not afford impact owners therefore minimal in the future loss of will involve to the A403 would adjacent to the inland area will to A403 the A403 highway assets in Area 1, space at Northwick historic evolution of the protection to waste close to the A403. short-term effects the coastal public construction works in be a relatively A403 will impact require a large would make an including Redwick intended for environment coast. The area disposal sites within Substantial change on landscape or access route. The close proximity to a simple design, existing land use. embankment, adaptive approach and some freshwater habitat assets, but would close to Severn Area 1, potentially to the landscape visual amenity. In facility presently popular road with however it is likely The large number although no coastal unsuitable due to properties at mitigation is largely provide no flood Beach may be allowing character of Area 1 the long-term, used for bird potentially high speed that construction of road crossings to erosion protection repeated Northwick. Some of protected by the defence to areas expected to contaminants to be close to the coast however, sea level watching will be traffic, requiring would require access undefended will be required. interference with the potential area realigned defences. close to the coast. develop into a more released into the can be expected. rise likely to restrict exposed to greater effective traffic closure of the assets will Maintenance may the transport intended for This will expose saline habitat. adjacent Existing agricultural public access and flood risk. management. No highway. potentially require be expected to be network. habitat mitigation known and Initial narrowing of designated areas. and pasture use affect visual significant service Modification to the deployment of an moderate due to Introduction of a at Northwick would unknown assets the intertidal area The ground may become less amenity along transmission road itself to act as Operations team to the length of the new structure not be protected. close to the coast across much of conditions are not productive as Severn Way and infrastructure will be a flood defence close flood gates. defence. adjacent to the to more regular Area 1 will be as well defined salinity increases. result in long term encountered. The would require more A403 may permit inundation and expected, however along set back landscape residual health and complex design and adaptive change damage. breaching of the defence alignment character change. safety risk to the civil works. over time to existing defences 2. public will be address increasing may be required. relatively low. flood risk There is potential for the development of a new bay between the First and Second Severn crossings. 2 Improve Coastal Defence Supports preferred The defences along Protection of the Land take on Historic Much of the Severn More geotechnical Widening of the Limited and Recreation and Construction of flood The coastal Flood defences The cost of flood (coastal) – Existing policy of ‘Hold the the existing coast Avonmouth docks coastal saltmarsh environment assets estuary coast in information is flood defence localised effects on amenity use within defences within a alignment can along the existing defence along the Seaward line’, which is in for much of Area 2 and the residential may be required, within Area 2 are Area 2 is made available along the footprint on the low quality Area 2 is not working dock will benefit from alignment will take existing alignment alignment keeping with the covers the and industrial although it is likely better known, with ground and is existing defence landward face of industrial landscape common due to the introduce significant avoiding the advantage of the is highly dependent port’s preference Avonmouth docks development that widening and listed buildings and intended for future alignment. Much of the existing character and predominance of H&S risks, largely difficult rerouting existing structure, on the form of
for a coastal area. The lock gates further inland will increase in a Scheduled use as a deep sea the area within the embankment along visual amenity. industrial based on the large of services required making efficient defence within alignment can be replaced at provide the largest elevation of flood Monument inland. berth. The existing Avonmouth docks the River Avon is Visual impact from development and vessels accessing the at the docks. The use of land areas. Avonmouth docks. a future date when potential benefits. defences can be Flood defences defence is a hard area is made not expected to elevated defences the Avonmouth area and the high potential to The lock gates of The need to the standard of The port supports achieved by along the existing structure, and ground, potentially affect land use in would be expected dock facilities. The traffic flows which combine flood the docks will provide erosion protection needs to proposals to increasing the alignment will modification of the requiring deeper this area. Flood as a result of effect of raising the may be expected. The defence works with require closure by protection at the be increased, improve protection footprint of the protect the known structure in this piles for new defences within the reduced visibility of existing flood docks also contain the new deep staff from the EA toe of flood however other to port assets. structure on the and unknown area would not defence structures. Avonmouth docks estuary, however defence alignment fuel storage depots at water berth Operations team or defences may be works within the landward side of assets. alter the alignment are unlikely to visual receptors is likely to be the coast, which pose facilities may avoid Bristol Ports necessary if coastal port area may need the defences. or form of defence. result in a change likely to be of low neutral, with no net an additional risk the need to Company. squeeze becomes a to be implemented It is therefore not to the land use. sensitivity and benefit or impact during construction. construct a new significant concern. at a specific date to expected that any potentially minor on recreational and The docks are located structure in this avoid impacting the geomorphological increase in defence amenity use in the on made ground, section. Upgrading port operations. change will occur. crest elevation in future. which may include of the small flood The port supports a on the berth side, Area 2 are likely to some contaminants. wall in the north of phased approach the improvement of make the impact An offshore pipeline Area 2 is a well the defence above minor. close to Holes Mouth understood water would not outfall will need to be engineering alter the defence effectively considered solution, while line nor the and managed during changes to the ‘hardness’ of the design and flood embankment wall so there would construction. These along the River be very little impact H&S concerns are Avon will be on geomorphology largely applicable to achieved without Potential coastal future maintenance significant design squeeze will be activities. concerns. restricted to the
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River Avon embankment. Set Back Does not support There are no The realignment No direct impact on Flood defences Realignment of The ground Realignment Potential Recreation and Construction close to A high The low-lying The new and large Defence 1 – ‘Hold the line’. Port restrictions for behind the existing the existing behind the flood defences are conditions along behind the permanent loss of amenity use within the railway line will embankment or ground along this structure required Realigned does not favour adaptive changes to dock area protects intertidal area or Avonmouth docks not expected to this alignment may Avonmouth docks existing screening Area 2 is not introduce significant flood wall will be realignment will for flood defence behind this option the flood defences all assets except for designated areas. will protect the cause allow for shorter area will potentially vegetation adjacent common due to the H&S concerns during necessary to require a large will incur large Avonmouth behind the the dock area, The railway line is a same historic reconfiguration of piles than the require a high to railway. Visual predominance of both initial provide the footprint that capital docks Avonmouth docks. including the potential habitat environment assets the port area, or existing alignment. defence with a receptors generally industrial construction and for required standard makes inefficient expenditure. railway line, area for birds and as the defence impact the local Ground conditions large footprint due of low sensitivity development. future maintenance of protection The use of space. The Maintenance of the
residential areas, reptiles, and may along the existing geomorphology. are moderately well to the lower ground except for Realignment activities. close proximity to alignment would flood gates will be and the sites for contain bat roosts. alignment. The There is the defined, however level. Change in residential behind the Construction within the railway line will also require a large an ongoing future industrial Phasing of works Avonmouth docks potential for the further detail will land use may be properties backing Avonmouth dock the popular industrial complicate number of requirement, with development. The may avoid bird include no listed dock to be flooded be difficult to required, although onto railway line in facilities is likely to area will require construction, as will crossings that high labour input docks are not as nesting season. buildings, and is during extreme collect due to the the proximity of the Avonmouth. Visual have a negligible careful traffic the provision of would need to be due to the safety protected, and the Works prior to built on made events leading to proximity of the alignment to the amenity of these impact on management to services to the managed by the EA requirements of port does not construction may ground that is the outflow of flood railway line. railway line receptors likely to recreational and mitigate the risk of docks. Several flood Operations team to working close to favour this option. be possible to expected to contain water once the tidal suggests that the be affected to a amenity use in the additional traffic on gates will be ensure that the the railway line. encourage common no unknown assets. level in the Severn land may not be of minor to moderate future. the network. required to required standard species to move falls, but this is high value. The port degree. maintain road of protection is away from the unlikely to does not support access. provided. works areas. Piling significantly impact this option. cleared vegetation the sediment after site clearance dynamics of the may allow nearshore. remaining fauna to Realigned defences move to adjacent will allow retreat of areas the coast along the River Avon. Set Back Does not support There are no Flood protection No direct impact on Realignment Realignment of The ground Realignment Limited numbers of Recreation and Close proximity to a A high The low-lying The new and large Defence 2 – ‘Hold the line’. restrictions for provided to very the existing further inland will flood defences are conditions along further inland will low sensitivity amenity use within wide range of services embankment or ground along this structure required Realigned Port does not adaptive changes to few assets or intertidal area or expose some of the not expected to this alignment may require a high visual receptors are Area 2 is not that support the flood wall will be realignment will a for flood defence through favour this option the flood defences potential future designated areas. known assets to cause allow for shorter defence with large present close to the common due to the industrial necessary to large footprint that will incur large Avonmouth behind the assets, offering The scrub land is a more regular reconfiguration of piles than the land take due to alignment. Larger predominance of developments. achieve the makes inefficient capital Avonmouth docks. very limited potential habitat flooding. The larger the port area, or existing alignment, the low-lying defences would be industrial Construction within required standard use of space. The expenditure.
benefits. The docks for protected area of undefended impact the local however little GI ground. Much of necessary due to development. the popular industrial of protection. The alignment would Maintenance of the are not as species. Phasing of space will expose geomorphology. data is available. the area inland of lower ground levels Realignment area will require provision of also require a large flood gates will be protected, and the works to avoid bird additional unknown There is the the existing than other options, behind the careful traffic services to the number of an ongoing port does not nesting season. assets to potential potential for the development is which would Avonmouth dock management to docks will require crossibgs that requirement. favour this option damage. dock to be flooded intended for require removal of facilities is likely to mitigate the risk of additional would need to be during extreme industrial screening have a minimal additional traffic on consideration managed by the EA events leading to development as vegetation, impact on the network. within the design of Operations team to the outflow of flood part of the ASEA, hedgerows, scrub recreational and the flood defence. ensure that the water once the tidal and loss of such and some mature amenity use in the Several flood gates required standard level in the Severn land would impact trees. future. will be required to of protection is falls, but this is potential revenue maintain road provided. unlikely to and job creation. access to significantly impact The docks are not undefended the sediment as protected, and locations. dynamics of the the port does not nearshore. favour this option Realigned defences will allow retreat of the coast along the River Avon. 3 Improve Coastal Defence Supports preferred It is unlikely that an Protecting the The freshwater This option will Flood defences The existing Improving defences Raising the level of Improvements Flood defences along The highly confined Use of existing The more (coastal) – Existing policy of ‘Hold the adaptive approach railway will offer habitat mitigation protect the heavy along the existing alignment offers along the existing existing defence along the existing the existing defence site will significantly structures will significant hard seaward line’ can be employed significant would be protected anti-aircraft battery alignment will protection to the alignment may line would defence alignment alignment will involve complicate reduce the total structures that may alignment for the existing additional benefits from saline scheduled result in narrowing former ICI waste require permanent potentially result in will protect the construction in close construction volume of new be required at the alignment. over realignment intrusion. The monument at of the intertidal disposal site and larger limited adverse public access along proximity to the activities. The material required coast will likley Modification to the options. Protection defences would Chittening as well area seaward of the preventing possible temporary visual impacts on the coast and will railway line, requiring proximity of the to provide effective lead to high capital existing railway of Severn Beach likely impact the as Severn Beach defences. The wide contaminants from footprints in the residential increase the flood clear and effective railway line may flood defence. The costs and ongoing embankment will realise existing saltmarsh and its area of saltmarsh in being released into intertidal area. receptors of high protection to the site rules to mitigate restrict the avoidance of flood maintenance should be substantial benefits in intertidal area archaeological the southern the adjacent Landscape sensitivity at Severn recreation and the risk. Works at the construction gates for access will requirements. The completed a single from the large with the footprint value. Construction section of Area 3 environmentally character of the Beach due to amenity facilities former ICI waste methodology reduce the need to impact on the time to avoid number of of the defence works are unlikely would narrow and designated areas. intertidal area is reduced visibility of within Severn disposal site may adopted. Access at deploy EA intertidal habiatat disruption of residential and extending seaward. to have an impact transition to Generally good GI likely to change as a estuary views. Beach. expose construction Severn Beach is Operations team that may be transport. The commercial Steel sheet piling on known heritage mudflat. The data is available. consequence of Users of Severn workers to relatively good, staff during necessary would potential buildings. All future on the seaward assets. former ICI waste coastal squeeze. Way and highway contaminants, although extreme events. require mitigation, environmental industrial areas will side of the railway disposal site will be will be relatively requiring additional accommodating an further increasing impacts of a new be protected. embankment protected, and may unaffected as safety measures. elevated crest level cost. Complicated defence seaward of would cause become a headland defence height of Seabank Power within the existing site access and the railway line will permanent loss of as the coastline the new structure Station is immediately constraints may be tidal conditions will likely favour a intertidal area, either side migrates would be similar to adjacent to the flood difficult. increase costs. single construction requiring habitat further inland, with the existing railway defences, placing programme. mitigation. a potential for embankment. additional H&S Ecological issues in outflanking. Landscape impacts restrictions on the north of Area 3 likely to be minor construction are less significant due to limited scale activities. as the intertidal of works required Maintenance habitat is in poorer to raise existing activities will be condition, although defence line. required close to the defences may still railway line. impact these areas.
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Set Back Does not support Realignment No flood defence The intended The heavy anti- Set back defence 1 No protection is Realignment Potential visual Realigned defences Flood defences will be The highly confined Taking advantage Less erosion Defence 1 – ‘Hold the line’ but behind the railway for the railway line freshwater habitat aircraft battery will be constructed afforded to the landward of the benefit to footpath will not provide constructed between site for improving of the high ground protection will be Realignment to the set back line may permit an would significantly mitigation area scheduled in close proximity former ICI waste railway line will users if Severn Way flood defence to the railway line and flood defence along along the A403 required in the new behind the alignment only adaptive approach lower the potential would be protected monument at to the de facto disposal site, require a high partly re-routed the public access the A403, requiring the existing alignment will flood defence as railway line excludes the for the benefits available. from saline Chittening will be defence, and may potentially leading structure with a along defence crest along the existing clear and effective alignment will reduce the height the railway line will railway, and improvement of The lack of damage. Potential protected by the therefore lead to to the release of potentially large as this would coast, which will be site rules to mitigate significantly and footprint of dissipate wave
protects all other flood defence, protection to habitats for reptiles flood defences coastal squeeze for contaminants into footprint, however enable elevated lost over time as the risks created by complicate the defence energy prior to it assets. A hybrid although changes Severn Beach and nesting birds in landward of the much of Area 3. The the adjacent the space seaward views over estuary the coast retreats. rail and road traffic. construction required. A new reaching the alignment may be to the A403 would substantially scrub land behind railway line, type of defence environmentally of the A403 is over a 2km+ length. The amenity beach Seabank Power activities. The structure will realigned defence, possible to highway would lower the potential the defences will however the lack of adopted is more designated areas. undeveloped and is Visual amenity of and public open Station is immediately proximity of the require flood gates however an incorporate make an adaptive benefits from also be protected flood defence will likely to have a Generally good GI not intended for residential spaces at Severn adjacent to the flood railway line and to permit access to entirely new alignment behind approach residential and from flood risk and expose the listed larger impact on data is available. future industrial receptors at Severn Beach will also be defences, placing A403 highway may undefended areas defence will incur the railway line and unsuitable due to commercial habitat changes. buildings at Severn the geomorphology development, Beach will be exposed to higher additional H&S restrict the at Severn Beach, substantial costs. the current Severn repeated properties. Realignment Beach. The loss of and habitat therefore its use unaffected in the flood risk, with restrictions on construction necessitating Beach FDS interference with further inland close areas close to the resilience than the may be acceptable. short term but inundation of the construction methodology deployment of the the transport to Severn Beach coast will also defence alignment. increasingly less so recreation and activities. adopted. EA Operations network. will cause damage increase the risk of At Severn Beach the in longer term as amenity areas as Maintenance team staff during to hedgerows. flooding to promontory that existing defence well as the activities will be extreme events. Timing of unknown assets. the Bridge and line deteriorates. transport required close to the works/sensitive site village are built on The public access infrastructure to highway. clearance. Use of is unlikely to along the coast will reach them protective fencing change. The estuary be unaffected in to exclude channel in this area the short term, construction areas is dominated by the however the long- from surrounding outcropping rock term loss of public habitats of value to and is unlikely to access and visual be retained. change in amenity would be formation. Macro expected. Highway scale changes in the users will be estuary may result relatively in the deposition of unaffected as additional sediment future defence on the shore, height would be although such similar to the changes are existing railway unclear. embankment. Minor localised landscape character change in short-term increasing in time and scale as Severn Beach becomes increasingly susceptible to flooding. Set Back Does not support Realignment Realignment along The intended Set back defence 2 Set back defence 2 No protection is Realignment Potential visual Realigned defences Flood defences will be The highly confined Taking advantage Less erosion Defence 2 – ‘Hold the line’ behind the railway the A403 would freshwater habitat will not provide may lead to coastal afforded to the landward of the benefits to users of will not provide constructed between site for improving of the high ground protection will be Realignment line may permit an offer a low mitigation area flood defence to squeeze for much former ICI waste railway line will Severn Way less flood defence to the railway line and flood defence along along the A403 required in the new adjacent to adaptive approach standard of would be protected the scheduled of Area 3 as the disposal site, require a high pronounced (1km the public access the A403 requiring the existing alignment will flood defence as A403 for the protection for both from saline monument at flood defence will potentially leading structure with a instead of 2km) but along the existing clear and effective alignment will reduce the height the railway line will improvement of the railway line and damage. Potential Chittening, and will be constructed in to the release of potentially large otherwise impacts coast, which will be site rules to mitigate significantly and footprint of dissipate wave flood defence, Severn Beach as habitats for reptiles not provide close proximity to contaminants into footprint, however the same as Set lost ofver time as the risks created by complicate the defence energy prior to it although changes per Set Back and nesting birds in protection to the the de facto the adjacent the space seaward Back Defence 1. the coast erodes. rail and road traffic. construction required. A new reaching the to the A403 Defence 1. It would scrub land behind known and defence. At Severn environmentally of the A403 is The amenity beach Seabank Power activities. The structure will realigned defence, highway would provide limited the defences will unknown assets at Beach the high designated areas. undeveloped and is and public open Station is immediately proximity of the require flood gates however an make an adaptive flood protection to also be protected Severn Beach. defences along the Generally good GI not intended for spaces at Severn adjacent to the flood railway line and to permit access to entirely new approach the industrial from flood risk and existing alignment data is available. future industrial Beach will also be defences, placing A403 highway may undefended areas defence will incur unsuitable due to development at habitat changes. are unlikely to development, exposed to higher additional H&S restrict the at Severn Beach, substantial costs. repeated Chittening. Realignment permit landward therefore its use flood risk, with restrictions on construction necessitating interference with further inland close migration of may be acceptable. inundation of the construction methodology deployment of the the transport to Severn Beach habitats, leading to recreation and activities. adopted. EA Operations network. will cause damage coastal squeeze. amenity areas as Maintenance team staff during to hedgerows. The narrower well as the activities will be extreme events. Timing of intertidal areas will transport required close to the works/sensitive site dissipate less wave infrastructure to highway. clearance. Use of energy allowing reach them protective fencing larger wave to exclude conditions at the construction areas coast. from surrounding habitats of value to be retained. Improve Full structural This approach will Desilting will be Desilting of the Removal of silt will No negative Desilting will allow No geo- No land take or The landscape and This approach will Desilting of the area Desilting of the Sea level rise may Regular (fluvial) repairs, safety is aligned with part of an ongoing outfalls will have potential impacts are greater discharge environmental risk change in visual amenity not impact around the outfall outfall structures be expected to maintenance improvements ‘Hold the line’ maintenance increase the temporary impact expected from this through the outfalls is expected from landscape character would be recreation and and within the has been previously increase the activities and costs and continued regime that is capacity to on aquatic option. within the study this option. is expected from unaffected by this amenity use of the culverts will become conducted as part frequency with associate with desilting necessary to discharge surface invertebrate area. this option. option. Negligible area. safer. However, of the ongoing which desilting disposal may effectively manage flooding thereby assemblages. landscape residual health and maintenance activities are create a relatively
surface drainage, reducing flood risk, Marginal habitat character change. safety issues will programme. necessary. high whole life cost and will form part however regular retained by limiting remain. Continuing this of an adaptive desilting will be desilting to the activity should face management necessary to inner sections of few difficulties. maintain the the channels.
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programme for the increased capacity. flood defences. This aligns with the preference for improving or optimising the performance of existing asset rather than building new structures. Additional This approach will Additional culverts Creation of new Addition of new No negative Additional culverts No geo- Minor increase in Minor localised This approach will Work required within Accommodating Introduction of High cost culverts within is aligned with can be added in an culverts will culverts will cause impacts are within the existing environmental risk land area required landscape and not impact tidal environment. additional culverts new culverts will associated with the the rhine ‘Hold the line’ adaptive manner to increase the substantial expected from this structure will is expected from to introduce visual impacts. recreation and Disruption to highway within the existing increase the complex capital network accommodate the capacity of localised damage, option. increase the total this option. additional culverts amenity use of the from engineering flood defences discharge capacity works and additional discharge through including capacity of the and widened area. works will require should be during extreme potential effects discharge the existing coastal vegetation removal outfalls, however channels at the traffic management. achievable, events, but may that the works requirements, embankment and and long term the specific outfall. although the exacerbate would have on the however it will be other impact in the arrangement proximity of the problems during A403 highway and more cost effective embankments intertidal area employed may railway line and low flow the railway line to complete works within Area 4. through the result in lower flow A403 may restrict conditions. in a single Assuming no provision of a rates through each the construction construction restrictions within permanent man- individual culvert, methodology and programme the rhines this will made structure. encouraging timing. reduce flood risk siltation. from surface water. Increase the size This approach will Increases to the Increasing the Additional land No negative Increasing the rhine No geo- Minor increase in Minor localised This approach will The side slopes of the Few constraints will Increasing the size Substantial of the rhine is aligned with capacity of the capacity of the take for the new impacts are network will environmental risk land area required landscape and not impact rhines may be steep affect the widening of the rhine excavation and network ‘Hold the line’ rhine network may rhine network will rhine network may expected from this increase the is expected from to widen rhine visual impacts. recreation and and will require care of the rhine network will have disposal of material be completed as allow for temporary have very small option. capacity to store this option. network. The wider amenity use of the to avoid falls, slips network. minor impact on will be necessary. demand increases storage of impact on existing surface flood channels may result area. and trips. Care for land use in the Regular over time, allowing additional surface hedgerows and waters, however in lower water level services passing area, and will allow maintenance will work to be water within the habitat areas. the discharge to the during normal across the site continuation of also be required to scheduled when channels, however Widening rhines Severn estuary will operation and (including high agricultural use ensure that the required. the discharge may will provide still be limited by cause a drop in the voltage power lines, within the vicinity rhines do not be limited by silted additional habitat the capacity of the overall ground will be necessary). of the rhines. It become silted, outfalls, or a small area for protected existing outfalls. water level. may be necessary reducing the total number of culverts species. A carbon This may result in to deploy staff to storage capacity. in the existing calculation will be high water levels ensure rhines are structure. undertaken on the within the rhines not blocked during outline design to for extended extreme events. identify any periods of time. The significant carbon extended period of footprint to be discharge may avoided where provide some possible through benefit from design choices. scouring accrete material within the culverts and on the estuary face of the outfalls. Additional This approach will The construction of Creation of Additional land Identification of The temporary No geo- Increase in land Potential landscape This approach will The side slopes of the Constraints Loss of land to Relatively high storage (dry is aligned with new storage ponds temporary storage take for the new suitable locations storage of surface environmental risk take to and visual benefits not impact rhines may be steep affecting the accommodate initial capital costs ponds) ‘Hold the line’ within the ASEA can areas will provide storage areas may will prevent flood water will is expected from accommodate if storage areas recreation and and will require care creation of additional storage, to create storage be implemented additional capacity have very small damage to historic allow discharge this option. temporary storage, preserve existing amenity use of the to avoid falls, slips additional dry however interim areas. Maintenance over time, however to manage surface impact on existing environment through the existing however the area field pattern and area, and may offer and trips. Care for storage areas will use may be will be necessary to the areas will need water, which will hedgerows, habitat assets. outfalls. The required is grassland cover. opportunities for services passing be highly pursued. While ensure that the to be identified and be discharged areas and extended period of currently unknown. improvement. across the site dependent on the productivity for areas remain reserved at an early through the outfalls associated species discharge may Some potential (including high specific locations agriculture and funtional between date. over a longer they support. Work provide some change in land use voltage power lines, identified. pasture ay be extreme events. period of time. This will provide benefit from for storage areas, will be necessary. affected, the land approach is additional habitat scouring accrete although may still be put to susceptible to flood areas for protected material within the agriculture may still use beyond its risk when multiple species. culverts and on the be possible. flood management events happen over estuary face of the function. a short period of outfalls. time, but this risk can be designed for/ managed.
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Appendix B: Hallen Marsh Option Sketches
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Appendix C: Northwick Option Sketches
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Appendix D - Economic Analysis
1.1.1 Construction Stage Impacts The main economic impacts generated in the construction phase relate to direct and indirect employment creation and gross value added (GVA) generation. The direct effects capture the change in employment and economic output attributable to the design and build process itself. The indirect effects capture the knock‐on implications for the supply chain that supports construction industries and benefits from increased expenditure within that industry. 1.1.1.1 Direct GVA impacts Direct GVA impacts are calculated through the application of best‐practice turnover‐to‐GVA ratios provided in the West of England LEP’s Support Manual. The Support Manual recommends a range of ratios between 0.37 and 0.43 to convert turnover to GVA. A midpoint ratio of 0.4 has been utilised. Applying this ratio to the scheme turnover of (capital expenditure only), suggests a total GVA impact of £33.2m. 1.1.1.2 Direct Employment Impacts Direct employment impact is calculated through the application of best‐practice ‘cost‐per‐job’ benchmarks listed in the Support Manual. The guidance indicates that £90,000 (2014 prices) of infrastructure investment is required to sustain one full‐time equivalent (FTE) employee. This benchmark was manually adjusted using ONS GDP deflators to £91,263 (2016 prices) to ensure consistency with the price base used for other benefit streams. Given that the estimated turnover equates to , this benchmark suggests of investment could support gross direct FTEs. 1.1.1.3 Indirect GVA Impacts It is likely that much of the construction contractors’ supply chain requirement will be met in the local area. Most expenditure will therefore be locally based and support local firms, so the upper‐ end of the multiplier range suggested by the Support Manual guidance has been used. Applying a multiplier of 1.9 to the direct GVA impact noted above results in a total direct and indirect GVA impact of during the construction phase. 1.1.1.4 Indirect Employment Impacts Similarly, to supply chain requirements, it is likely that much of the construction contractors’ employment requirement will be met in the local area. Hence, the upper‐end of the multiplier range in the guidance was therefore used. Applying the multiplier 2.0 to the direct employment impact noted above results in a total direct and indirect employment impact of employment opportunities created during the construction phase. 1.1.2 Operational Stage Impacts The methodology adopted to assess the following three categories of potential operational stage economic impacts of the project are presented below: Existing economic activity safeguarded, associated with reduced business downtime at existing commercial premises; Recent and future economic activity unlocked and/or safeguarded, associated with the strategic development aspirations for ASEA; and, Business rate uplift generated, associated with the rates payable at any commercial properties developed since the onset of the City Deal in 2013. 1.1.3 Existing Economic Activity Safeguarded Although the ASEA area is designated for significant employment‐led development going forward, the area is already home to a thriving business community. Nevertheless, because current flood defences are not consistent or adequate to provide a 1 in 200‐year Standard of Protection (SoP) across the entire flood cell, existing businesses are currently at significant risk from coastal flooding. This means that affected businesses are threatened by periods of temporary closure (and in extreme cases, permanent closure) in the wake of flood events. This results in business downtime and the potential for lost economic output within the West of England sub‐region. Within this context, provision of enhanced flood defences up to a 1 in 200‐year SoP (based on hybrid 2076 and 2098 design levels [i.e. taking into account climate change, coastal change and sea level rise]) will reduce the level of flood risk that existing businesses are subject to. As a result, the scale of temporary (and permanent) business closure, associated business downtime and lost economic output within the West of England will all be reduced where a suitable flood defence solution is implemented. 1.1.3.1 Methodology To estimate the impact of the flood defence scheme on existing economic activity, an approach was adopted that is aligned to the Joint Defra/EA FCERM R&D programme’s (project FD2662) ‘Flood and coastal erosion risk management and the local economy’ toolkit. The approach attempts to explore and capture the local economic benefits of flood risk management, measured in terms of local income or GVA. The approach to assessing the value of existing economic activity safeguarded can be summarised as follows: Existing commercial properties inundated by different flood events were identified using EA’s National Receptor Dataset (NRD), overlain on flood extent mapping. The commercial floorspace associated with affected properties was obtained from NRD, split by economic sectors using Multi‐Coloured Manual (MCM) codes. Floorspace data was converted to employment by sector using employment density benchmarks sourced from the Homes and Communities Agency’s (HCA) ‘Employment Densities Guide’ (2015). Employment estimates were converted to annual GVA values using GVA per employee benchmarks sourced from the 2015 Annual Business Survey (ABS). The scale of GVA lost as a result of a specific flood events (e.g. 50% AEP, 20% AEP, 10% AEP etc) was estimated for the Do Nothing, Do Minimum and Do Something scenarios, based on the number of businesses (and subsequently floorspace, employment and GVA) affected by each flood event and the recovery period for affected businesses. Recovery periods were based on industry benchmarks and professional experience and varied by sector. The resulting GVA impacts were converted to annual average values before being extrapolated over the appraisal period and discounted to determine present values. The difference in ‘lost’ GVA associated with business downtime across the scenarios represents the safeguarded GVA resulting from following a particular flood defence solution. Further, the Joint Defra/EA FCERM R&D programme’s toolkit is explicit in its advice that certain businesses will relocate or face closure under threat of flood risk. In particular, a small proportion of businesses with medium/high adaptive capacity and low location dependence will relocate to alternative accommodation with less threat of flood risk. Similarly a small proportion of businesses with low adaptive capacity will face permanent closure. As such, in addition to the temporary losses in GVA alluded to above, the assessment captures the scale of GVA that could be permanently lost to the local area as a result of businesses relocating or closing due to flood risk. It is also worth noting that the safeguarding economic activity assessment focussed on GVA impacts of affected properties. In contrast, the economic appraisal developed for the FDGiA business case focussed on avoided capital damages for residential and commercial properties rather than operational impacts at commercial properties, meaning there is no risk of double counting impacts. That said, from a methodological perspective, the safeguarding economic activity assessment was consistent with the economic appraisal prepared for the FDGiA business case in a number of ways: Common appraisal period of 100 years, including fixed horizon years (2016, 2046, 2076 and 2116); Common use of key data inputs (flood modelling extents, refined version of NRD); Consistent use of annualisation, interpolation and discounting techniques. 1.1.3.2 Economic Impacts on Existing Commercial Properties Floorspace Affected Based on the approach described above, Table A.1 demonstrates that the hybrid 2076/2098 flood defence solution will result in significantly less inundated commercial floorspace than the Do Nothing and Do Minimum scenarios, across multiple flood events and across the appraisal period. As an illustrative example, by 2116, around 1.3 million sq m of commercial floorspace will be at risk of inundation based on a 1 in 200 year flood event under Do Nothing conditions. Under the Do Minimum scenario, the quantum of at‐risk floorspace falls to around 961,000 sqm, before falling to 717,000 sq m under the preferred flood defence option.
Table A.1. Commercial Floorspace Inundated Source: EA NRD, CH2M Defence Scenario/Climate Flood Event Change Epoch
Do Nothing 1 in 5 1 in 10 1 in 20 1 in 50 1 in 75 1 in 100 1 in 200
2016 133 133 133 4,676 5,017 7,762 8,055
2046 133,540 218,434 253,433 370,164 402,266 480,312 535,907
2076 208,559 271,441 393,186 528,350 617,766 665,296 815,606
2116 510,594 622,249 736,232 982,812 1,055,901 1,210,146 1,294,794
Do Minimum 1 in 5 1 in 10 1 in 20 1 in 50 1 in 75 1 in 100 1 in 200
2016 133 133 133 4,676 5,017 7,762 8,055
2046 133 133 4,904 5,900 8,055 8,449 17,520
2076 4,904 6,069 8,055 11,143 13,912 22,768 91,879
2116 11,469 14,179 35,104 208,906 303,940 527,867 960,686
Do Something (2076/2098) 1 in 5 1 in 10 1 in 20 1 in 50 1 in 75 1 in 100 1 in 200
2016 133 133 133 133 133 133 171
2046 133 133 133 171 171 171 1,073
2076 133 133 171 1,073 1,081 1,199 13,763 2116 1,073 1,081 3,371 78,678 110,625 329,176 716,813
Employment Affected The quantums of floorspace listed in Table A.1 are translated into employment estimates in Table A.2, based on the aforementioned HCA employment density benchmarks. The analysis demonstrates that based on a 1 in 200 year flood event in 2116, the quantum of employment affected ranges from more than 31,000 under Do Nothing conditions to around half (17,000) under the preferred flood defence option.
Table A.2. Employment at Inundated Commercial Floorspace – Business Downtime Source: EA NRD, CH2M, HCA Defence Scenario/Climate Change Epoch Flood Event
Do Nothing 1 in 5 1 in 10 1 in 20 1 in 50 1 in 75 1 in 100 1 in 200
2016 6 6 6 156 169 258 266
2046 4,852 6,605 7,475 9,929 10,552 11,812 13,246
2076 6,580 8,100 10,352 12,943 14,629 15,781 19,567
2116 12,628 14,753 17,797 23,731 25,514 28,786 30,615
Do Minimum 1 in 5 1 in 10 1 in 20 1 in 50 1 in 75 1 in 100 1 in 200
2016 6 6 6 156 169 258 266
2046 6 6 163 186 266 281 510
2076 163 210 266 338 395 636 2,064
2116 352 409 942 4,981 7,218 12,440 23,058
Do Something (2076/2098) 1 in 5 1 in 10 1 in 20 1 in 50 1 in 75 1 in 100 1 in 200
2016 6 6 6 6 6 6 7
2046 6 6 6 7 7 7 32
2076 6 6 7 32 32 32 419
2116 32 32 139 2,011 3,021 7,908 17,228
GVA Affected – Business Downtime The affected employment estimates outlined in Table A.2 are translated into estimates for lost GVA per event in Table A.3, following application of GVA per employee and business downtime benchmarks. The analysis demonstrates that for following a 1 in 200 year event in 2116, the scale of GVA lost as a result of flooding could amount to £1.4 billion under the Do Nothing scenario, falling to £1.1 billion in the Do Minimum scenario and £820m under the preferred flood defence solution.
Table A.3. GVA Lost per Event (£) Source: EA NRD, CH2M, HCA, ABS Defence Scenario/ Climate Change Flood Event Epoch
Do Nothing 1 in 5 1 in 10 1 in 20 1 in 50 1 in 75 1 in 100 1 in 200 2016 £416,142 £416,142 £416,142 £7,468,546 £8,057,711 £12,861,229 £13,398,505
2046 £226,539,589 £317,772,757 £361,250,883 £490,173,234 £522,991,873 £578,587,737 £643,302,807
2076 £323,547,314 £395,976,855 £510,937,837 £632,547,174 £698,525,945 £751,396,565 £924,587,911
2116 £618,500,966 £703,766,559 £847,152,272 £1,110,616,933 £1,197,929,597 £1,337,601,692 £1,408,391,246
Do Minimum 1 in 5 1 in 10 1 in 20 1 in 50 1 in 75 1 in 100 1 in 200
2016 £416,142 £416,142 £416,142 £7,468,546 £8,057,711 £12,861,229 £13,398,505
2046 £416,142 £416,142 £7,886,993 £9,202,998 £13,398,505 £13,791,471 £27,839,788
2076 £7,886,993 £9,837,133 £13,398,505 £16,652,067 £20,147,336 £35,740,536 £104,976,175
2116 £17,714,796 £21,077,733 £46,974,191 £237,672,389 £346,042,683 £609,162,486 £1,082,767,850
Do Something (2076/2098) 1 in 5 1 in 10 1 in 20 1 in 50 1 in 75 1 in 100 1 in 200
2016 £416,142 £416,142 £416,142 £416,142 £416,142 £416,142 £484,936
2046 £416,142 £416,142 £416,142 £484,936 £484,936 £484,936 £2,137,224
2076 £416,142 £416,142 £484,936 £2,137,224 £2,137,224 £2,137,224 £20,629,680
2116 £2,137,224 £2,137,224 £5,620,361 £104,119,369 £145,150,254 £411,223,055 £820,184,277
However, it should be noted that the figures in Table A.3 reflect GVA impacts per event. In order to calculate the annual average loss in GVA under each scenario, the per event losses outlined above were multiplied by event frequencies and aggregated for each horizon year. The resulting annual average GVA losses in each horizon year are outlined in Table A.4, and demonstrate that losses are significantly smaller across all horizon years under the preferred flood defence solution, relative to Do Nothing and Do Minimum scenarios.
Table A.4. Annual Average GVA Loss – Business Downtime Source: EA NRD, CH2M, HCA, ABS Horizon Year Scenario 2016 2046 2076 2116
Do Nothing £133,287 £10,908,451 £14,801,615 £24,607,736
Do Minimum £133,287 £271,759 £848,934 £8,143,308
Do Something (2076/2098) £11,071 £21,313 £137,409 £5,448,529
Further to the business downtime impacts associated with temporary closure of commercial properties described from Table A.1 to A.4, some businesses are expected to relocate out of the West of England or permanently close in response to flood risk. The Joint Defra/EA FCERM R&D programme’s toolkit suggests that businesses in sectors such as manufacturing have low adaptive capacity to flood risk and are therefore particularly perceptible to permanent closure or relocation. Specifically, the toolkit suggests that between 1% and 5% of such businesses may permanently close or relocate. Using the 1% benchmark to provide a conservative estimate of the impact of implementing the preferred flood defence solution, the total scale of annual GVA lost from the West of England sub‐ region in response to flood risk is estimated at between £1.7 million (Do Nothing) and £1.0 million (preferred flood defence solution) by 2116. Table A.5. Annual GVA Loss – Permanent Closure/Relocation Source: EA NRD, CH2M, HCA, ABS Horizon Year Scenario 2016 2046 2076 2116
Do Nothing £85,223 £883,384 £1,317,871 £1,714,210
Do Minimum £85,223 £112,442 £244,657 £1,363,371
Do Something (2076/2098) £4,849 £4,849 £35,713 £1,035,683
The present value of annual average GVA losses from temporary and permanent closures/relocation can be interpreted by interpolating between the horizon year values and applying the prevailing discount rate over the 100‐year appraisal period. By following this approach, the present value of GVA losses are outlined in Table 4.6. The analysis demonstrates that the preferred flood defence solution could reduce lost GVA from £263m (Do Nothing) or £27m (Do Minimum) to around £11m. Therefore, the present value of safeguarded GVA at existing businesses could amount to £252m versus the Do Nothing scenario or £16m versus the Do Minimum scenario, over the 100‐year appraisal period.
Table A.6. Present Value of Safeguarded GVA Source: EA NRD, CH2M, HCA, ABS GVA Metric
Scenario PV of Safeguarded GVA PV of Safeguarded GVA PV of Lost GVA vs. Do Nothing vs. Do Minimum
Do Nothing £262,625,562
Do Minimum £26,637,257 £235,988,305
Do Something (2076/2098) £10,951,294 £251,674,268 £15,685,963
1.1.4 Recent and Future Economic Activity Unlocked and/or Safeguarded 1.1.4.1 Avonmouth Severnside Enterprise Area The ASEA development area is a 1,800ha site, of which 650ha was earmarked for future development as part of sub‐regional economic and development planning in recent years. Strategic aspirations for ASEA include the delivery of more than 1.5 million sq m of employment floorspace. ASEA is also looking to deliver between 6,000 and 12,000 jobs by 2026, primarily in the logistics/warehousing and industrial sectors. From a planning policy perspective, delivery of an appropriate flood defence solution and associated ecological mitigation are critical to unlocking the full extent of development at ASEA and achieving these ambitious objectives. The project is also vital to safeguarding recent development activity at ASEA, which may not otherwise comply with current planning and environmental policy. In effect, fulfilment of the long‐term economic aspirations for ASEA is contingent on interventions proposed by this project. To assess the extent of recent and future development dependency on the project, the following stages of analysis were undertaken, which are described in more detail below: Identification of development plots and plot characteristics including: Flood risk with and without the project; Status, in terms of whether plots have recently been developed/are within the development pipeline or whether they are aspirational/future development opportunities; Compliance with planning and environmental requirements with and without the project; Scale, in terms of plot size (hectares) and floorspace (sq m). Establishment of land use mix and development proposals for all development plots, to determine floorspace mix; Estimate of gross job creation potential based on land use and floorspace mix; Estimate of gross GVA uplift based on job creation estimate; Conversion of gross impacts to net impacts, utilising relevant factors of additionality.
Identification of Plots The development area is fragmented across multiple land owners, with a range of developers promoting individual plots of land within ASEA. In order to identify plot characteristics, including ownership, developer interest, location, shape, size and development proposals, SGC and BCC provided land inventories for the ASEA area falling within their boundaries. SGC and BCC also provided mapping showing the approximate position of each future development plot within ASEA. This allowed CH2M to digitise the inventory, meaning that the position and size of each development plot relative to flood risk mapping and planning considerations such as the 1957/58 planning consent and fiscal boundaries could be understood. The digitised version of the ASEA development plots is presented in Figure A.1.
Figure A.1: ASEA Development Plots Source: SGC, BCC, CH2M
Plot Characteristics Flood Risk Figure A.2a demonstrates that all development plots across Avonmouth and Severnside are at risk from a 1 in 200‐year flood event without intervention.
Figure A.2a: Flood Extent without intervention (1 in 200‐Year Flood Risk) Source: CH2M Simultaneously, Figure A.2b demonstrates that all development plots in Avonmouth and Severnside will be free from flood risk during a 1 in 200‐year flood event following intervention. Combined, Figures A.2a and A.2b suggest that the project will alleviate flood risk issues for development plots within ASEA and ensure compliance with the the Environment Agency’s (EA) recommended standard of protection for new developments (i.e. 1 in 200 years).
Figure A.3b: Flood Extent with Intervention (1 in 200‐Year Flood Risk) Source: CH2M Development Plot Status A number of the development plots in the Avonmouth section of ASEA have already received planning approval, with development works completed and occupiers on site in some cases, Further, although those development plots identified as ‘future’ in Severnside are yet to be built, the 1957/58 planning envelope allows development at most plots to come forward within the consented area, without reference to current planning requirements and environmental regulations relating to flood risk. Compliance with Planning and Environmental Requirements Nevertheless, recent, current and future development across ASEA must recognise and acknowledge the findings of the Severnside and Avonmouth Wetland Habitat Project Stage 1 & 2 (also known as the Cresswell Report). In the case of Avonmouth, BCC’s planning and economic development officers have advised that recently and currently developed plots were allowed to proceed on the basis that ecological mitigation would be delivered retrospectively, to meet the requirements of the Cresswell Report. Similarly, future development at plots within the 1957/58 planning envelope would still require SGC to provide compensatory wetland habitat as a form of ecological mitigation. In both cases, the responsibility for delivering this mitigation now lies with the local authorities. In reality, neither BCC or SGC are able to fund the significant flood and ecological works required as part of the project. LEP support is required to provide a strategic and integrated solution as well as upfront capital funding. This will remove the medium‐to‐long term operational risk associated with non‐compliance with the Cresswell Report for recent development at Avonmouth and future development within the 1957/58 planning envelope at Severnside. The project can make the recent and future developments acceptable in planning terms. Within this context, recent development at Avonmouth and future development within the 1957/58 planning envelope can be described as safeguarded by the project. This means that whilst development has already or can proceed in the absence of the project, the project retrospectively ensures compliance with planning and environmental regulations and reduces planning risk. As such, the economic impacts associated with such development can be described as safeguarded by the project. In addition, there are some plots in Avonmouth that are not subject to planning applications or planning approvals at present. Similarly, there are some plots in Severnside that fall outside of the 1957/58 planning envelope and would therefore need to comply with current planning standards and environmental regulations. Such development can be described as dependent on the project, as the project provides the flood and ecological mitigation that may otherwise be unaffordable on a plot‐by‐plot basis or through local authority funding. As such, the economic impacts associated with such development can be described as created or unlocked by the project. Development Scale In light of the differentiation of development plots described above, Table A.7 presents a summary of the plot inventory for future development sites in ASEA, split by current status (for Avonmouth) and location inside/outside of the 1957/58 planning envelope (for Severnside). This provides the basis for understanding the scale of development that is safeguarded or unlocked by the project. Note that Site A01 in Avonmouth is assumed to support no future development, based on advice from BCC planners regarding the likelihood of development commencing at that location.
Table A.7. ASEA Future Development Plot Inventory Source: SGC, CH2M Floorspace (sq m)
Avonmouth Plots: Current Severnside Plots: Location Status Land Owner/ Developer Built/ Not Inside 57/58 Outside 57/58 Total ASEA Approved: Developed: Envelope: Envelope: Safeguarded Unlocked Safeguarded Unlocked
Severnside: Harrow n/a n/a 347,234 ‐ 347,234 Estates/Robert Hitchins Ltd
Severnside: Gazeley Logistics Property Partnership n/a n/a 8,748 20,853 29,601 (SEGRO/Moorfield)
Severnside: Bericote n/a n/a 111,484 ‐ 111,484
Severnside: Unknown/Not n/a n/a 487,173 ‐ 487.173 Stated
Severnside Subtotal n/a n/a 954,640 20,853 975,493
Avonmouth: A01 0 ‐ n/a n/a 0
Avonmouth: A02 16,785 ‐ n/a n/a 16,785
Avonmouth: A03 38,520 ‐ n/a n/a 38,520
Avonmouth: A04 19,350 ‐ n/a n/a 19,350
Avonmouth: A05 17,325 ‐ n/a n/a 17,325
Avonmouth: A07 27,045 ‐ n/a n/a 27,045
Avonmouth: A08 53,415 ‐ n/a n/a 53,415 Avonmouth: A09 7,740 ‐ n/a n/a 7,740
Avonmouth: A10 4,050 ‐ n/a n/a 4,050
Avonmouth: A11 6,390 ‐ n/a n/a 6,390
Avonmouth: A12 ‐ 20,070 n/a n/a 20,070
Avonmouth: A13 30,870 ‐ n/a n/a 30,870
Avonmouth: A14 35,145 ‐ n/a n/a 35,145
Avonmouth: A15 78,075 ‐ n/a n/a 78,075
Avonmouth: A16 38,700 ‐ n/a n/a 38,700
Avonmouth: A17 54,450 ‐ n/a n/a 54,450
Avonmouth: A18 3,960 ‐ n/a n/a 3,960
Avonmouth: A19 ‐ 9,450 n/a n/a 9,450
Avonmouth: A20 2,880 ‐ n/a n/a 2,880
Avonmouth: A21 ‐ 21,870 n/a n/a 21,870
Avonmouth: A22 14,895 ‐ n/a n/a 14,895
Avonmouth: Hallen Marsh ‐ 15,120 n/a n/a 15,120
Avonmouth Subtotal 449,595 66,510 n/a n/a 516,105
Total 1,491,598
The inventory suggests that around 450,000 sq m of employment floorspace in Avonmouth is already built/approved. This scale of development is safeguarded by the project. Around 67,000 sq m of floorspace is not developed yet; this scale of development is unlocked by the project. In terms of Severnside, some 955,000 sq m of floorspace is located within the 1957/58 planning envelope. This scale of development is safeguarded by the project. Around 21,000 sq m of floorspace lies outside of the 1957/58 planning envelope and is therefore unlocked by the project. In total, combining the various elements from Avonmouth and Severnside, some 1.45 million sq m of floorspace is safeguarded by the project with 88,000 sq m unlocked (Figure A.3).
Figure A.3: Unlocked and Safeguarded Development at ASEA Source: SGC, BCC, CH2M (Note that the Avonmouth Development Plot ‘Hallen Marsh’ does not feature on Figure A.3. This is recognised as unlocked development in this analysis)
It is worth nothing that for the Severnside plots, there is residual uncertainty about land ownership/developer interest. Further, it was not possible to establish detailed information on plot size, proposed floorspace or intended land use. Therefore, high level assumptions were made to convert plot sizes to floor area using a best practice plot ratio of 0.45 for industrial and warehousing (from Office for the Deputy Prime Minister’s ‘Employment Land Reviews: Guidance Note’ [2004]). This process is reflected in the floorspace metrics reported in Table A.7 above. Further, through discussion with BCC and analysis of planning conditions attached to certain development plots in the Avonmouth area, the following plots are assumed to be independent of the proposed interventions and are not considered to be safeguarded or unlocked by the project: A01 – as noted above, BCC planners confirmed that development would be unlikely to commence at this location due to deliverability constraints. A03 – discounted on the basis that the approved planning application contained site‐specific habitat/ecological mitigation conditions that were required prior to development. Development at this site is therefore already safeguarded from future planning risks, independent of the current project. A04 – discounted on the basis that the approved planning application contained site‐specific habitat/ecological mitigation conditions that were required prior to development. Development at this site is therefore already safeguarded from future planning risks, independent of the current project. A22 – discounted on the basis that the approved planning application contained no conditions relating to a requirement for land raising or other flood defence/ecological mitigation. Development is therefore considered to be fully compliant with planning regulations already. For all other plots in ASEA, flood defence and ecological mitigation will make recently‐built and future developments inside and outside the 57/58 planning envelope acceptable in planning and environmental terms. The associated economic outputs in terms of jobs and GVA will therefore be safeguarded (for recent development) or unlocked (for future development) as a result of the project. Land Use Mix As noted above, the land use mix proposed for future development at ASEA is expected to be dominated by logistics/warehousing and industrial properties. However, previous studies have conflicting approaches to the distribution of plots and floorspace between B2 and B8 land uses. In particular, the ODS presented a number of land use mix scenarios, including: Scenario 1 – 100% of development designated as B8; Scenario 2 – 75% of development as B8, 25% as B2; Scenario 3 – 50% of development as B8, 50% as B2. The ODS also allows for a small proportion of Sui Generis land uses (c. 5%). In contrast, the Amion Model, which presents a consolidated model of business rate growth and economic and employment impact across designated Enterprise Zone and Enterprise Areas in the West of England adopts the following land use mix for future development at ASEA: Reference Case – 76% of development designated as B8, 24% as B2; Intervention Case – 81% of development as B8, 19% as B2; Given that B2 land uses typically have a higher employment density and generate higher levels of GVA per employee compared to B8 land uses, a conservative approach to assessment would select a land use mix that reduces the scale of B2 land use in favour of B8. Further, property market analysis indicates that demand for B8 land use outweighs demand for B2 in the sub‐region. For these reasons, the economic development assessment undertaken is aligned with the Amion Model ‘Intervention Case’ land use mix described above, which assumes a propensity for B8 development. Development Profile The Amion Model was used to forecast the development profile of ASEA under the reference and intervention cases. For the purposes of the present assessment, the reference and intervention cases are defined as follows: Reference Case: Covering those development plots that are not contingent on the project as they have already achieved planning and environmental compliance: Avonmouth: as established above this includes A01, A03, A04 and A22. Severnside: adopting a conservative approach, this includes all sites within the 1957/58 planning envelope (even though it is established above that these could be regarded as safeguarded plots) Intervention Case: Covering those development plots, both recently developed, in development and proposed for the future, that are contingent on the project to ensure long‐term planning and environmental compliance: Avonmouth: safeguarded development at plots A02, A05‐11, A13‐18, A20 (already built/in development) and unlocked development at plots A12, A19, A21, Hallen Marsh (proposed future development). Severnside: unlocked development outside the 1957/58 planning envelope (proposed future development). As noted above, the intervention case allows additional development plots at Avonmouth and Severnside to come forward as a result of provision of flood defence and ecological mitigation. Further, the intervention case also accelerates the timing of delivery of development at plots within the 1957/58 planning envelope at Severnside. This relates to the project providing greater confidence and certainty for developers in such plots, leading to a more rapid onset of development. The rate of accelerated development promoted by the project in the intervention case is consistent with the acceleration rate and resulting development profile assumed in the Amion Model. Both of these project impacts (additional development and accelerated development) are demonstrated in the development profiles assumed under the reference and intervention cases outlined in Table A.8a to A.8c. In summary, the Tables demonstrate that the project will: More than 443,000 sq m of floorspace safeguarded (c. 377,000 sq m) or unlocked (c. 67,000 sq m) at Avonmouth; Nearly 21,000 sq m of floorspace unlocked at Severnside; Around 464,000 sq m of floorspace safeguarded (c. 377,000) or unlocked (c. 87,000 sq m) across ASEA.
Table A.8a: ASEA Development Profile ‐ Avonmouth Source: BCC, CH2M, Amion Model Floorspace (sq m) Floorspace (sq m)
Int. Case Int. Case
Case Case
Year Ref. Safeguarded Unlocked Accelerated Total Additional Year Ref. Additional Safeguarded Unlocked Accelerated Total 2016 72,765 376,830 0 0 449,595 376,830 2028 0 0 2,467 0 2,467 2,467
2017 0 0 0 0 0 0 2029 0 0 2,467 0 2,467 2,467
2018 0 0 7,597 0 7,597 7,597 2030 0 0 2,102 0 2,102 2,102
2019 0 0 4,844 0 4,844 4,844 2031 0 0 1,757 0 1,757 1,757
2020 0 0 5,386 0 5,386 5,386 2032 0 0 1,757 0 1,757 1,757
2021 0 0 3,628 0 3,628 3,628 2033 0 0 1,757 0 1,757 1,757
2022 0 0 4,165 0 4,165 4,165 2034 0 0 1,757 0 1,757 1,757
2023 0 0 4,165 0 4,165 4,165 2035 0 0 1,757 0 1,757 1,757
2024 0 0 4,165 0 4,165 4,165 2036 0 0 1,757 0 1,757 1,757
2025 0 0 4,165 0 4,165 4,165 2037 0 0 2,093 0 2,093 2,093
2026 0 0 4,165 0 4,165 4,165 2038 0 0 2,093 0 2,093 2,093
2027 0 0 2,467 0 2,467 2,467 Total 72,765 376,830 66,510 0 516,105 443,340
Table A.8b: ASEA Development Profile ‐ Severnside Source: SGC, CH2M, Amion Model Floorspace (sq m) Floorspace (sq m)
Int. Case Int. Case
Case Case
Year Ref. Safeguarded Unlocked Accelerated Total Additional Year Ref. Additional Safeguarded Unlocked Accelerated Total 2016 29,648 0 0 29,648 0 2028 37,072 773 ‐1,663 36,183 ‐889
2017 15,442 0 0 15,442 0 2029 37,072 773 ‐1,663 36,183 ‐889
2018 15,442 2,382 74,388 92,212 76,770 2030 37,072 659 ‐6,902 30,829 ‐6,243
2019 46,586 1,519 10,686 58,790 12,204 2031 37,072 551 ‐11,857 25,765 ‐11,307
2020 74,197 1,689 ‐10,518 65,367 ‐8,830 2032 37,072 551 ‐11,857 25,765 ‐11,307
2021 66,258 1,137 ‐14,185 53,211 ‐13,047 2033 37,072 551 ‐11,857 25,765 ‐11,307
2022 63,084 1,306 ‐3,299 61,090 ‐1,993 2034 27,612 551 ‐2,397 25,765 ‐1,846
2023 63,084 1,306 ‐3,299 61,090 ‐1,993 2035 22,824 551 2,391 25,765 2,942
2024 63,084 1,306 ‐3,299 61,090 ‐1,993 2036 22,824 551 2,391 25,765 2,942
2025 63,084 1,306 ‐3,299 61,090 ‐1,993 2037 29,442 656 601 30,700 1,257
2026 63,084 1,306 ‐3,299 61,090 ‐1,993 2038 29,442 656 601 30,700 1,257
2027 37,072 773 ‐1,663 36,183 ‐889 Total 954,640 20,853 0 975,493 20,853
Table A.8c: ASEA Development Profile ‐ ASEA Source: BCC, SGC, CH2M, Amion Model Floorspace (sq m) Floorspace (sq m)
Int. Case Int. Case
Case Case
Year Ref. Safeguarded Unlocked Accelerated Total Additional Year Ref. Additional Safeguarded Unlocked Accelerated Total 2016 102,413 376,830 0 0 479,243 376,830 2028 37,072 0 3,240 ‐1,663 38,650 1,57
2017 15,442 0 0 0 15,442 0 2029 37,072 0 3,240 ‐1,663 38,650 1,57
2018 15,442 0 9,979 74,388 99,809 84,367 2030 37,072 0 2,761 ‐6,902 32,931 ‐4,14
2019 46,586 0 6,362 10,686 63,634 17,048 2031 37,072 0 2,308 ‐11,857 27,522 ‐9,55
2020 74,197 0 7,074 ‐10,518 70,753 ‐3,444 2032 37,072 0 2,308 ‐11,857 27,522 ‐9,55
2021 66,258 0 4,765 ‐14,185 56,839 ‐9,419 2033 37,072 0 2,308 ‐11,857 27,522 ‐9,55
2022 63,084 0 5,471 ‐3,299 65,256 2,172 2034 27,612 0 2,308 ‐2,397 27,522 ‐8
2023 63,084 0 5,471 ‐3,299 65,256 2,172 2035 22,824 0 2,308 2,391 27,522 4,69
2024 63,084 0 5,471 ‐3,299 65,256 2,172 2036 22,824 0 2,308 2,391 27,522 4,69
2025 63,084 0 5,471 ‐3,299 65,256 2,172 2037 29,442 0 2,749 601 32,793 3,35 2026 63,084 0 5,471 ‐3,299 65,256 2,172 2038 29,442 0 2,749 601 32,793 3,35
2027 37,072 0 3,240 ‐1,663 38,650 1,578 Total 1,027,405 376,830 87,363 0 1,491,598 464,19
1.1.4.2 Gross Economic Activity Unlocked Assumptions Building on the floorspace assumptions outlined for the reference and intervention cases in Tables A.8a to A8c, the economic and employment impacts associated with the project were estimated within the framework provided by the Amion Model. The Amion Model, originally set up to support the West of England City Deal in 2012/13, was updated so that key inputs reflected current best practice data. The following assumptions were incorporated into the amended Amion Model: Use of employment density benchmarks sourced from the HCA’s ‘Employment Densities Guide’ (2015), in particular, use of 77 sq m per employee for B8 and 36 sq m per employee for B2. Use of a persistence factor of ten years to capture the duration of GVA benefits for each job created at ASEA, in line with recommendations within HCA’s ‘Calculating Cost per Job | Best Practice Note’ (2015). Use of GVA per employee benchmarks in line with Table A.9. Variable benchmarks were used to forecast GVA uplifts at Severnside (SGC) and Avonmouth (BCC), to reflect the different baseline levels of productivity in each local authority area, sourced from ONS’ ‘Regional and Subregional Productivity’ data tables (2017). In particular, national benchmarks for each employment sector were sourced from the Annual Business Survey (ABS) before being weighted by the relative level of productivity in SGC and BCC from the ONS data tables. Appraisal period of 23 years between 2016 and 2038, to tie in with the end of the West of England City Deal. Discount Rate of 3.5% in line with HM Treasury Green Book recommendations.
Table A.9. GVA per Employee Benchmarks Source: ABS, ONS, CH2M Land Use Sector Bristol South Gloucestershire
B2 General industry £62,199 £68,745
B8 Storage & distribution £58,930 £65,132
Gross Employment Impact Based on the floorspace profiles outlined in Table A.8a to A.8c, the aforementioned land use mix (81% B8 and 19% B2) and the employment density benchmark outlined above (77 sq m per employee for B8 and 36 sq m per employee for B2), the employment impact of the project is presented in Tables A.10a to A.10c. In summary, the employment impact comprises: Nearly 7,000 gross FTEs safeguarded (c. 5,900) or unlocked (c. 1,050) across Avonmouth; More than 300 gross FTEs unlocked at Severnside Around 7,300 gross FTEs safeguarded (c. 5,900) or unlocked (c. 1,400) across ASEA.
Table A.10a: ASEA Gross Employment Impact ‐ Avonmouth Source: BCC, CH2M, Amion Model
Y e a r Gross Jobs (FTE) Y e a r Gross Jobs (FTE) 2025 2024 2023 2022 2021 2020 2019 2018 2017 2016 2027 2026 2025 2024 2023 2022 2021 2020 2019 2018 2017 2016 Table 2027 2026 Source: SGC, CH2
Year
A.10b:
1,147 1,044 1,169 Ref. Case ASEA Ref. Case 584 994 994 994 994 994 734 243 243 467
0 0 0 0 0 0 0 0 0 0 0 M, Amion Model
Gross 5,938
Safeguarded Employment Safeguarded 0 0 0 0 0 0 0 0 0 0 0
Gross
Unlocked 120 Unlocked 18 27 66 66 66 66 57 85 76 12 21 21 21 21 21 24 38 39 66 Int. Int. 0 0 0 0
Impact Jobs
Case Case
(FTE)
1,172 ‐ ‐ Accelerated ‐ Accelerated 168 224 166 ‐ ‐ ‐ ‐ ‐ ‐ 26 52 52 52 52 52 Severnside
0 0 0 0 0 0 0 0 0 0 0 0 0 0
1,453 7,084 1,030 Total Total 570 963 963 963 963 963 926 838 120 243 467 66 66 66 66 57 85 76 39 66
0
1,210 5,938
‐ ‐ Additional Additional 192 120 206 139 ‐ ‐ ‐ ‐ ‐ ‐ 14 31 31 31 31 31 66 66 66 66 57 85 76 39 66 0 0 0
Total Total 2038 2037 2036 2035 2034 2031 2030 2037 2036 2035 2034 2033 2032 2031 2028 2038 2030 2033 2032 2029 2029 2028 Year
15,042
Ref. Case 1,147 Ref. Case 464 464 360 360 435 584 584 584 584 584 584 0 0 0 0 0 0 0 0 0 0 0
Safeguarded 5,938 Safeguarded 0 0 0 0 0 0 0 0 0 0 0 0
Gross 1,048
329 Unlocked Unlocked 10 10 10 33 28 28 28 28 28 28 39 33 33 12 12 39 9 9 9 9 9 9
Int. Int. Jobs
Case Case
(FTE)
‐ ‐ ‐ ‐ Accelerated Accelerated 109 187 187 187 ‐ ‐ ‐ 38 38 38 26 26 0 9 9 0 0 0 0 0 0 0 0 0 0 0 0
15,371
Total 8,132 Total 406 406 406 484 484 486 406 570 570 406 406 33 28 28 28 28 28 28 39 33 33 39
6,986 ‐ ‐ ‐ 178 329 178 178 ‐ ‐ ‐ ‐ Additional Additional 46 46 29 20 20 98 33 28 28 28 28 28 28 39 33 14 14 33 39 Table A.10c: ASEA Gross Employment Impact ‐ ASEA Source: BCC, SGC, CH2M, Amion Model Gross Jobs (FTE) Gross Jobs (FTE)
Int. Case Int. Case
Case Case
Year Ref. Safeguarded Unlocked Accelerated Total Additional Year Ref. Safeguarded Unlocked Accelerated Total Additional 2016 1,614 5,938 0 0 7,551 5,938 2028 584 0 51 ‐26 609 25
2017 243 0 0 0 243 0 2029 584 0 51 ‐26 609 25
2018 243 0 157 1,172 1,573 1,329 2030 584 0 44 ‐109 519 ‐65
2019 734 0 100 168 1,003 269 2031 584 0 36 ‐187 434 ‐150
2020 1,169 0 111 ‐166 1,115 ‐54 2032 584 0 36 ‐187 434 ‐150
2021 1,044 0 75 ‐224 896 ‐148 2033 584 0 36 ‐187 434 ‐150
2022 994 0 86 ‐52 1,028 34 2034 435 0 36 ‐38 434 ‐1
2023 994 0 86 ‐52 1,028 34 2035 360 0 36 38 434 74
2024 994 0 86 ‐52 1,028 34 2036 360 0 36 38 434 74
2025 994 0 86 ‐52 1,028 34 2037 464 0 43 9 517 53
2026 994 0 86 ‐52 1,028 34 2038 464 0 43 9 517 53
2027 584 0 51 ‐26 609 25 Total 16,189 5,938 1,377 0 23,503 7,314
Gross GVA Impact Through application of the location and sector‐specific GVA per employee benchmarks (Table A.9) to the gross FTE estimate (Tables A.10a to A.10c), in combination with adoption of the appropriate discount rate (3.5% per annum) and a persistence factor of ten years, these employment impacts translate to the present value gross GVA uplift impacts outlined in Tables A11a to A11c. These i
Note that accelerated development at plots within the 1957/58 planning envelope is a key driver of the GVA impacts in Severnside in particular, given that earlier development leads to earlier creation of jobs and therefore earlier GVA generation, reflected in higher GVA in present value terms.
Table A.11a: ASEA Gross GVA Impact ‐ Avonmouth Source: BCC, CH2M, Amion Model Gross GVA Impacts (£m) Gross GVA Impacts (£m)
Year ef . C a s Int. Case Year ef . C a s Int. Case Ad diti on al 2026 2025 2024 2023 2022 2021 2020 2019 2018 2017 2016 2027 2026 2025 2024 2023 2022 2021 2020 2019 2018 2017 2016 Table 2027 Source: SGC, CH2M, Amion Model
Year
A.11b:
ASEA £397 £395 £383 £347 £307 £264 £218 £165 £101 Ref. Case £50 £52 £54 £56 £58 £60 £62 £64 £66 £69 £59 £46 £31 £0 £0
Gross
£261 £271 £280 £290 £300 £311 £321 £333 £344 £356
Safeguarded GVA Safeguarded £0 £0 £0 £0 £0 £0 £0 £0 £0 £0 £0 £0 £0 £0
Gross
Impact
GVA £28 £10 £10 £29 Unlocked £26 £24 £22 £20 £17 £15 £11 Unlocked £9 £8 £8 £7 £6 £5 £4 £2 £0 £0 £7 £0 £0 Int. ‐
Severnside Impacts
Case
Accelerated Accelerated £36 £40 £44 £49 £53 £68 £80 £73 £30 £33
£0 £0 £0 £0 £0 £0 £0 £0 £0 £0 £0 £0 £0 £0 (£m)
£429 £395 £359 £319 £277 £238 £185 £134 £438 £437 £404 £411 £425 Total £338 £347 £356 £366 £375 £385 £394 Total £46 £31 £28 £29
£339 £344 £356 Additional £288 £295 £302 £310 £317 £325 £332 £28 £29 £45 £49 £52 £55 £59 £73 £84 £75 £40 £42 £0 £0
Total Total 2029 2028 2038 2037 2036 2035 2034 2033 2032 2031 2030 2038 2030 2029 2028 Year 2037 2036 2035 2034 2033 2032 2031
Gross £5,624
Ref. Case GVA £592 £379 £399 £165 £175 £203 £233 £261 £286 £312 £342 £156 £0 £0 £0 £0 £0 £0 £0 £0 £0 £0 £0
Impacts £3,067 Safeguarded Safeguarded
(£m) £0 £0 £0 £0 £0 £0 £0 £0 £0 £0 £0 £0 £0 £0 £0 £0 £0 £0 £0 £0 £0 £0 £0
£366 £127 £20 £23 £25 Unlocked £10 £11 £13 £14 £16 £18 Unlocked £9 £8 £9 £3 £3 £4 £4 £5 £6 £6 £7 £3 £9 Int.
Case £211
‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ Accelerated Accelerated £31 £23 £22 £24 £28 £32 £33 £29 £25 £27 £20 £0 £0 £0 £0 £0 £0 £0 £0 £0 £0 £0 £0
£4,025 £5,961 Total Total £356 £384 £146 £154 £179 £205 £233 £262 £294 £322 £139 £20 £23 £25 £10 £11 £13 £14 £16 £18 £9 £9
£3,433 £338 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ £23 £15 £19 £20 £24 £27 £28 £24 £19 £20 £23 £25 £21 £17 Additional £10 £11 £13 £14 £16 £18 £9 £9 Table A.11c: ASEA Gross GVA Impact ‐ ASEA Source: BCC, SGC, CH2M, Amion Model Gross GVA Impacts (£m) Gross GVA Impacts (£m)
Int. Case Int. Case
Case Case
Year Ref. Safeguarded Unlocked Accelerated Total Additional Year Ref. Additional Safeguarded Unlocked Accelerated Total 2016 £100 £356 £0 £0 £456 £356 2028 £399 £0 £33 ‐£23 £409 £10
2017 £112 £344 £0 £0 £456 £344 2029 £379 £0 £30 ‐£31 £378 ‐£1
2018 £123 £333 £9 £73 £538 £414 2030 £342 £0 £27 ‐£27 £341 ‐£1
2019 £163 £321 £14 £80 £579 £416 2031 £312 £0 £24 ‐£25 £312 ‐£1
2020 £225 £311 £20 £68 £623 £398 2032 £286 £0 £22 ‐£29 £279 ‐£8
2021 £276 £300 £23 £53 £652 £376 2033 £261 £0 £19 ‐£33 £247 ‐£14
2022 £320 £290 £27 £49 £685 £365 2034 £233 £0 £17 ‐£32 £218 ‐£15
2023 £361 £280 £30 £44 £715 £354 2035 £203 £0 £15 ‐£28 £190 ‐£13
2024 £399 £271 £33 £40 £742 £343 2036 £175 £0 £13 ‐£24 £164 ‐£11
2025 £434 £261 £36 £36 £767 £333 2037 £165 £0 £12 ‐£22 £155 ‐£10
2026 £395 £0 £38 £33 £466 £71 2038 £156 £0 £12 ‐£20 £147 ‐£8
2027 £397 £0 £39 £30 £467 £69 Total £6,216 £3,067 £492 £211 £9,986 £3,771
1.1.4.3 Net Economic Activity Unlocked In order to establish an accurate estimate of the additional economic activity unlocked by the project at a sub‐regional level, it is necessary to convert the gross impacts outlined above into net impacts using standard additionality factors. This ensures that the assessment only captures the extent to which economic impacts accrue as a direct result of intervention, discounting those impacts that may have materialised anyway. Therefore, the conversion minimises the potential for over‐estimating impacts as a result of the project. In line with the West of England LEP’s ‘Impact Guidance Note’ (2015) and other best practice guides such as HCA’s ‘Additionality Guide’ (2014), the following additionality factors are considered in the gross to net impact conversion process: Deadweight: to capture the range of effects that would have occurred even in the absence of intervention (i.e. the Reference Case); Displacement: to capture the effects of new economic activity that could crowd out or displace existing economic activity; Leakage: to capture the effects that accrue beyond the sub‐region and do not benefit the target area; Substitution: effectively ‘within‐firm displacement’, capturing changes in behaviour including recruitment of jobless individuals to replace existing employees in response to a policy or intervention; Multiplier effects: to capture the effects of increased activity in local supply chains (indirect multiplier) and increased spending associated with those employed (induced multiplier) as a result of an intervention. The gross‐to‐net conversion process is underpinned by the following equation: Net Additional Impact = Net Impact in Intervention Case – Net Impact in Reference Case (i.e. Deadweight) Where the net impacts in the intervention and reference cases are captured using the formula: Net Impact (in Intervention Case or Reference Case) = Gross Impact (in Intervention Case or Reference Case)*(1‐Displacement)*(1‐Leakage)*Multiplier Effect For the purpose of this assessment, additionality factors for displacement, leakage and substitution were sourced from HCA’s ‘Additionality Guide’ (2014) based on subregional additionality. Multiplier factors were sourced from the LEP’s ‘Impact Guidance Note’ (2015). All factors are outlined in Table A.12:
Table A.12. Additionality Factors Source: ABS, ONS, CH2M Employment Output Factor Additionality Additionality
Leakage 10.4% 10.4%
Displacement 37.4% 37.4%
Substitution 0.0% 0.0%
Multiplier Effects 1.55 1.70 Combined, the net effect of gross‐to‐net conversion generates a net additionality factor of 87% for employment and 95% for GVA. This means that 87% of the gross employment impact and 95% of the gross GVA impact is net additional as a result of the Scheme. Given the net additionality ratios and through application of the additionality factors ( Table A.12) to gross impacts (Tables A.10a to A.10c and A.11a to A.11c), the net additional impacts of flood defence and ecological mitigation are presented in Tables A.13 and A.14 as well as summarised below:
l
al
‐
‐ ‐ ‐
‐
‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐ ‐ 1.1.5 Business Rate Uplift The project contributes to the Growth Incentive element of the City Region Deal. The Growth Incentive allows the West of England to retain and pool business rate growth over and above a defined baseline, for investment on economic development and infrastructure projects elsewhere in the West of England as part of the wider Economic Development Fund. The Growth Incentive mechanism allows the West of England LEP to provide capital funding for the project via the Economic Development Fund, on the basis that the funding is ‘repaid’ by business rate uplift once employment‐led development is realised at ASEA following project delivery. Within this context, it is necessary to assess the ability of the project to unlock sufficient business rate uplift to cover the capital funding provided by West of England LEP. The business rate growth assessment is predicated on two sources: The baseline net business rate charge for businesses in ASEA as of September 2012; The development assumptions underpinning the analysis presented in the preceding sections of this appendix. 1.1.5.1 Baseline Business Rates in ASEA The City Region Deal states that the baseline business rate charge at ASEA (and other enterprise areas) would be set at September 2012 values, with any growth in business rates after that date contributing to the principles of the City Region Deal. The Deal estimates the September 2012 business rate charge as £6.4 million per annum, comprised predominantly of business rates accruing in Avonmouth (£6.2 million) with a much smaller contribution from Severnside (£0.2 million). Given the City Region Deal is expected to remain in place until March 2038, the total baseline value of business rates in ASEA between 2016 and 2038 is estimated at £147m (constant prices). Therefore, any business rates collected over the appraisal period to March 2038 above this threshold can be incorporated into the City Region Deal pooling arrangements as part of the growth incentives proposal. 1.1.5.2 Future Development Potential at ASEA Pivoting from the development assumptions underpinning the economic case analysis, the project will allow the full potential of ASEA to be realised. As noted in Tables A.8a to A.8c, some 1.5 million sq m of commercial floorspace will exist at ASEA following implementation of the project, of which, some 375,000 sq m will represent recently developed (post‐baseline) floorspace that will be safeguarded by the project and some 87,000 sq m will represent additional floorspace that will be unlocked by the project. A range of warehousing and manufacturing firms will occupy this floorspace (and in some cases, already do), and will be liable to a business rate charge that will be retained by the West of England local authorities via the City Region Deal. These business rates are over and above the £6.4 million per annum baseline value established in 2012. The estimation of future business rate generation at ASEA is supported by the following assumptions: Rateable value of £86/sq m for B2 and B8 premises, in line with current rental values (Alder King South West Market Monitor 2016); Standard business rate multiplier of 0.497 adopted (valuation office agency, 2016/17); No change in business rate multiplier across the appraisal period; No inflationary change in rateable values across the appraisal period; No premises qualifying for the small business rate multiplier or small business rate relief. Site 34 sits outside the fiscal boundary for Severnside, therefore business rate generation at this site does not contribute to business rate uplift estimation; Site 74 already generates some £48,000 in business rates per annum in the baseline according to the Amion model, therefore any business rates associated with this plot is excluded from this model.
1.1.6 Economic Analysis Summary The outputs of the economic analysis outlined above is presented in Table A.16. The results of the analysis can be summarised as follows:
Both metrics demonstrate that the project represents very good value for money.
Appendix G - Risk Register ASEA Ecology Mitigation and Flood Defence Project
ASEA Ecology Mitigation and Flood Defence Project
RISK REGISTER / OUTPUTS
Details of the risk register and risk outputs are provided in this appendix as supporting information to the OBC.
The project has been subject to the risk management processes and techniques described in Environment Agency Operational Instruction 152_10 ‘Manual of Technical Guidance for Risk Management in ncpms Projects’. Risks were identified by the project team at progress meetings and at a dedicated risk workshop on 15th May 2017 attended by the Environment Agency, Bristol City Council and South Gloucestershire Council project leads.
Mitigation measures have been identified and as far as possible incorporated into the scheme proposals. Residual risks after mitigation have been quantified through team discussion and analysis using rates provided by the ESE Contractor. Enclosed within this appendix are the following files developed for use with the Palisade Decision Tools @Risk Software. The software has allowed multiple project outcome scenarios to be simulated and output from this has been used to determine risk budgets for incorporation into the economic assessment.
Table 1 List of Risk Management Files Title/Filename Details ‘IMSW002194-CH2-000-000-RA-GEN-0002’ Main risk register. Identifies key project risks, together with their probability of occurrence and consequences of them coming to fruition. Mitigation measures are shown. The residual risks are re-evaluated post-mitigation and quantified in terms of ‘Least Cost’, ‘Most Likely’, and ‘Maximum Cost’. ‘IMSW002194-CH2-000-000-RA-GEN-0004’ The Monte-Carlo risk simulation output file based on analysis of the risk register
At this stage of project development, all of the quantified risks are allocated to the client, and the results are presented in terms of ‘All Risks Excluding Big 7’, as required by the Operational Instruction. There are a number of Contractor Risks relating to Weather and Flooding, but allowance for these has been made within the ESE Contractor’s costed working methodology, so are not quantified in the risk register.
A selection of the risk output is shown on the following pages. Key data taken through to the economic assessment are:
In Table 2 (next page) the key project risks are listed and in Table 3 the full list of main risks, taken from the risk register. In Table 4 the consideration of Optimism Bias is presented.
ASEA Ecology Mitigation and Flood Defence Project
Table 2 Ranked List of Key Project Risks Risk Mean ID Simulation Rank Risk Item Risk Value (£k) 1 Risk 17938 Project is required to install piles from the railway due to environmental constraints. ID30 NR object to scheme proposals. Approval to work on NR land is initially refused. Effort and staff time to manage stakeholder engagement is higher than planned. Impact on contruction costs due to programme delays and onerous conditions. Design rework. 2 Risk 3690 Need for extensive rock armour ID25 3 Risk 3203 Influential stakeholder(s) object to scheme proposals. Planning, WFD compliance, ID13 EA Environmental Consent, End-user sign-off or other consent is refused due to disagreement with stakeholders on the nature or visual appearance of the scheme, environmental impact, extent of mitigtion or other reasons. or stakeholders require additional data and/or analysis to enable consent. Effort and staff time to manage stakeholder engagement is higher than planned. Impact on Contruction phase costs due to programme delays, additional capital works or onerous conditions. 4 Risk 1640 Local source of suitable fill material cannot be found or remote sources of material ID41 cannot be provided free from cost of transportation 5 Risk 1602 Adverse Weather Conditions delaying scheme construction - prolonged wet or cold ID6 conditions (this item does not account for flooding, see item 10) 6 Risk 1550 Unable to agree boundary or influence of SPA with NE. NE or other stakeholders ID17 demand intertidal compensation habitt to be provided by the scheme. Application of onerous conditions where working close to the SPA boundary 7 Risk 1384 Design change to avoid archaeology or to avoid heritage assets ID24 8 Risk 1312 Purpose of habitat areas changes to full or partial public access nature reserve. ID26 Significant changes to footpaths 9 Risk 1128 Stakeholder feedback during detailed design requires incorporation of more ID23 expensive defence-types, habitat types or accommodation works in order to gain approvals and consents, or to satisfy consent conditions. Project is required to take on existing assets (eg. Cotteralls Pill) 10 Risk 1025 Under-estimation of compensation budget for construction-related or permanent ID38 provable losses 11 Risk 846 Discovery of significant archaeology or heritage assets in scheme footprint ID14 12 Risk 846 Discovery of unexpected or unrecorded protected or rare species in scheme ID15 footprint or greater than expected effort required to achieve planned mitigation 13 Risk 808 Unsuitability of site-won soil for reuse in construction or need for soil treatment ID5 14 Risk 732 Discovery of UXO ID8 15 Risk 641 Flooding over the working area, but less than a 1:10 probability event, which is ID10 covered by Major Risk B7-2- Loss of material, degradation, replacement and clean- up 16 Risk 513 Project is unable to identify an operator for habitat areas, or agree terms of use, ID18 possible management costs 17 Risk 440 Discovery of unknown services affecting scheme design and/or injury to personnel ID7 18 Risk 320 Need for maintaining current SoP during construction phase not properly ID11 understood. Damage to completed flood defences after contractual completion but prior to establishment of vegetation 19 Risk 303 Discovery of contaminated land in the port and other historic industrial areas of the ID2 project, landfill areas, together with contamination on or on adjacent to railway land. Contaminants (eg. asbestos, hydrocarbons) in areas proposed for piling or excavation works 20 Risk 225 Unforseen hard ground or obstructions (eg. gravel lenses, buried structures, buried ID4 rock armour or railway ballast) affecting construction of foundations (eg. pile installation) ASEA Ecology Mitigation and Flood Defence Project
Risk Mean ID Simulation Rank Risk Item Risk Value (£k) 21 Risk 220 Discovery of unexpectedly soft, weak or permeable ground conditions in the ID3 coastal floodplain or in the existing defences, affecting foundation design and construction methodology 22 Risk 211 Land access difficulties including Bristol Port (access to works and procurement of ID36 site compounds). 23 Risk 205 Insufficient natural supply of fresh water to wetland scrapes and ponds ID19 24 Risk 205 Adequacy of Site Information. Project is unable to transfer risk to contractor ID42 25 Risk 51 Discovery of unforeseen invasive species in scheme footprint or greater than ID16 expected effort required to achieve mitigation 26 Risk 51 Increased footprint and changes to nature of flood defences from existing ID27 arrangements increases maintenance and requires new specialist equipment to enable safe maintenance
ASEA Ecology Mitigation and Flood Defence Project
Table 3 Key Risks Consequence Mitigation Probability Cost Impact Cost Impact Time Impact 1 Discovery of contaminated land in the port Safety/Health - Operational staff or the public could suffer burns or Treat on site or remove to licensed VL V VL and other historic industrial areas of the respitory problems, or action may be required to remove material from site tip H project, landfill areas, together with in accordance with a previously unplanned or more expensive safe contamination on or on adjacent to railway method of working land. Contaminants (eg. asbestos, Reputation - Discovery of contaminated material may alarm the public and hydrocarbons) in areas proposed for piling or this could manifest as criticism of the scheme and the promoting excavation works organisations Delay to Programme - Discovery of contaminants could lead to delay as a safe method of working is identified and agreed. Safe method may be more time consuming. Cost - Delays and more complex and expensive method of working or on- site treatment would lead to additional costs. Increased cost of transport and disposal at appropriately licensed tip facility. 2 Discovery of unexpectedly soft, weak or Delay to Programme - Discovery of soft ground could lead to delay as an Assumed not yet included in scheme M H VL permeable ground conditions in the coastal alternative alignment, source of material, foundation design or method of cost estimate. Excavate and replace floodplain or in the existing defences, working is identified and agreed. Possible need for soil treatment. These with additional Imported material from affecting foundation design and construction alternatives may be more time consuming to deliver. remote site or improve in-situ methodology Cost - Delays and more complex and expensive design or method of working would lead to additional costs. Increased cost of materials, plant and labour to account for changed design. 3 Unforeseen hard ground or obstructions Delay to Programme - Discovery of hard ground or obstructions could lead Excavate and remove obstructions M H VL (e.g.. gravel lenses, buried structures, buried to delay as an alternative alignment, source of material, foundation design rock armour or railway ballast) affecting or method of working is identified and agreed. These alternatives may be construction of foundations (eg. pile more time consuming to deliver. installation Cost - Delays and more complex and expensive design or method of working would lead to additional costs. Increased cost of materials, plant and labour to account for changed design. 4 Unsuitability of site-won soil for reuse in Delay to Programme - Discovery that excavated soil is unsuitable for use Ground investigation. Seek alternative M H VL construction or need for soil treatment in bank construction could lead to delay as alterntive source and disposal sources of material. Extend testing to sites re found, or a change to the methodology of working with existing off-site sources. Excavate and replace material is agreed. Alternative method may be more time consuming. with additional Imported material from Cost - Delays, or more complex and expensive method of working would alternative local site or improve in-situ lead to additional costs 5 Adverse Weather Conditions delaying Safety/Health - Operational staff could suffer from long working periods in Aim to construct earthworks in dryer M V H scheme construction - prolonged wet or cold cold or wet conditions, leading to mitigation in the form of reduced working months. Build in productivity and H ASEA Ecology Mitigation and Flood Defence Project
Table 3 Key Risks Consequence Mitigation Probability Cost Impact Cost Impact Time Impact conditions (this item does not account for hours. programme float. Assumed not yet flooding, see item 10) Delay to Programme - Wet or cold weather could obstruct some included in scheme cost estimate. Allow construction activities (eg. surface water flooding preventing access, wet for reduced productivity in programme weather affecting earthworks or cold weather affecting concrete and and budget brickwork). Cost - Delays could cause increased cost of standing plant and labour. 6 Discovery of unknown services affecting Safety/Health - Operational staff or the public could suffer as a result of a Develop a single combined services L V VL scheme design and/or injury to personnel services strike (burns, explosion, sewage discharge), or action may be record. Geophysical survey of potential H required to mitigate in accordance with a previously unplanned or more clashes and positive identification of expensive safe method of working services prior to detailed design. Plan Reputation - Discovery of unrecorded services or a services strike may diversions in detailed design phase. alarm the public and this could manifest as criticism of the scheme and the Allow for cost of unforeseen diversions promoting organisations in risk budget. Warning - services Delay to Programme - Discovery of unrecorded services could lead to diversions may not yet be included in delay as a diversion is put in place or a safe method of working is scheme cost estimate identified and agreed. Safe method may be more time consuming. Cost - Delays, diversions or more complex and expensive method of working would lead to additional costs. 7 Discovery of UXO Safety/Health - Operational staff or the public could suffer as a result of an XO desk study has been undertaken as L V VL explosion, or action may be required to mitigate in accordance with a part of the GI. Further work may be H previously unplanned or more expensive safe method of working required prior to construction, or the Reputation - Discovery of unrecorded UXO may alarm the public and this project may wish to transfer the risk to could manifest as criticism of the scheme and the promoting organisations the contractor. Allow for cost and cost of Delay to Programme - Discovery of unrecorded UXO could lead to delay delay due to unforeseen clearances in as a safe recovery or clearance is put in place or a safe method of risk budget working is identified and agreed. Safe method may be more time consuming. Cost - Delays or more complex and expensive method of working would lead to additional costs. Cost of UXO clearance. 8 Flooding over the working area, but less than Safety/Health - Operational staff could be forced to evacuate the working Maintain capacity of existing viewed L V H a 1:10 probability event, which is covered by area in flooding conditions, leading to reduced working hours rhines and outfalls. Ensure ESE H Major Risk B7-2- Loss of material, Reputation - Flooding may alarm the public and this could manifest as contractor and tendering permanent degradation, replacement and clean-up criticism of the scheme and the promoting organisations works contractors understand the Delay to Programme - Flooding could obstruct some construction activities requirements of the scheme. Allow for (eg. flooding preventing access, degradation of earthworks) downtime in programme and budget ASEA Ecology Mitigation and Flood Defence Project
Table 3 Key Risks Consequence Mitigation Probability Cost Impact Cost Impact Time Impact Cost - Delays could cause increased cost of standing plant and labour. Flooding could cause loss or damage to materials. 9 Need for maintaining current SoP during Delays to programme - EA Asset Protection will expect current SoPs to be Ensure ESE contractor and tendering L V VL construction phase not properly understood. maintained by the contractor during the construction period. If this is not permanent works contractors H Damage to completed flood defences after fully understood by the contractor, then this issue could lead to a reduction understand the requirements of the contractual completion but prior to in Sop or delays scheme. Assumed not yet included in establishment of vegetation Cost - Delays or change to construction methodology or rework could lead scheme cost estimate. Allow for reduced to increased cost. productivity in programme and budget 10 Influential stakeholder(s) object to scheme Reputation - Disputes with stakeholders could damage long-term relations Clarify uncertainties & scheme details H V V proposals. Planning, WFD compliance, EA between organisations. The general public may become aware and this with NE, SGC, BCC, HE, IDB and H H Environmental Consent, End-user sign-off or could manifest as criticism of the scheme and the promoting organisations others, prior to submitting formal other consent is refused due to Delay to Programme - Delay due to uncertainty as to whether the project planning application. Implement a disagreement with stakeholders on the will proceed. Disputes could obstruct consenting, and thus delay staged or Iterative design approach to nature or visual appearance of the scheme, commencement on site. Attempts to resolve disputes may require ensure project is 'right-first-time' on environmental impact, extent of mitigation or additional design work, data collection and analysis. Delay to programme submission of consent applications and other reasons. or stakeholders require to prepare statutory EIA & planning application at start of construction. Allow for delays additional data and/or analysis to enable Cost - Delays in obtaining consents or in agreeing designs could cause to the overall project, and additional consent. Effort and staff time to manage increased design costs or construction costs of standing plant and labour. design and consultation costs. Note stakeholder engagement is higher than Cost due to redesign of options or appealing decision other items linking to this key risk planned. Impact on Construction phase costs due to programme delays, additional capital works or onerous conditions 11 Discovery of significant archaeology or Delay to Programme - Discovery of protective species could lead to delay Archaeological desk study completed at H V VL heritage assets in scheme footprint as an appropriate method of working or translocation is identified and appraisal stage. Geotechnical H agreed with biodiversity stakeholders. Agreed method may be more time investigations have included consuming. archaeological watching brief. Further Cost - Delays and more complex and expensive method of working or site investigations planned in detailed translocation would lead to additional costs. Additional analysis and design. Allow for cost and cost of delay reporting. due to unforeseen archaeology in risk budget. Warning - overall scheme cost estimate may not yet allow for archaeological supervision costs 12 Discovery of unexpected or unrecorded Delay to Programme - Discovery of protective species could lead to delay Carry out comprehensive protected M V VL protected or rare species in scheme footprint as an appropriate method of working or translocation is identified and species surveys and continue to liaise H or greater than expected effort required to agreed with biodiversity stakeholders. Agreed method may be more time with NE and other biodiversity achieve planned mitigation consuming. stakeholders. Minimise scheme footprint ASEA Ecology Mitigation and Flood Defence Project
Table 3 Key Risks Consequence Mitigation Probability Cost Impact Cost Impact Time Impact Cost - Delays and more complex and expensive method of working or on known habitats. Allow for cost and translocation would lead to additional costs. Additional analysis and cost of delay due to unforeseen reporting protected species in risk budget. Warning - overall scheme cost estimate may not yet allow for planned protected species mitigation costs. This risk item relates to new protected species encountered post-planning or during construction 13 Discovery of unforeseen invasive species in Delay to Programme - Discovery of invasive species could lead to delay Carry out comprehensive invasive L M VL scheme footprint or greater than expected as an appropriate method of working or disposal is identified and agreed species surveys and continue to liaise effort required to achieve mitigation with biodiversity stakeholders. Agreed method may be more time with NE and other biodiversity consuming. stakeholders. Minimise scheme footprint Cost - Delays and more complex and expensive method of working or on known habitats. Allow for cost and disposal would lead to additional costs. Additional analysis and reporting. cost of delay due to unforeseen invasive species in risk budget. Warning - overall scheme cost estimate may not yet allow for planned invasive species mitigation costs. This risk item relates to new invasive species encountered post- planning or during construction 14 Unable to agree boundary or influence of Reputation - Disputes with NE could damage long-term relations between Clarify uncertainties & scheme details M V V SPA with NE. NE or other stakeholders organisations. The general public may become aware and this could with NE and others, prior to submitting H H demand intertidal compensation habitat to be manifest as criticism of the scheme and the promoting organisations formal planning application. Allow for provided by the scheme. Application of Delay to Programme - Delay due to uncertainty in boundaries or need for delays to the overall project, and onerous conditions when working close to intertidal mitigation habitat could lead to delayed agreement of HRA and additional design and consultation costs. the SPA boundary WFD compliance This item does not include for Cost - Resolution of any dispute may require change of alignment of flood procurement of additional intertidal defences, change in defence-type, or changes to construction habitat methodology, leading to increased costs 15 Project is unable to identify an operator for Reputation - Disputes with NE over viability of consented habitat if Commence early negotiations with M VH VL habitat areas, or agree terms of use, possible unmanaged could damage long-term relations between organisations. potential site operators. Allow a budget management costs The general public may become aware and this could manifest as criticism for initial period of monitoring and of the scheme and the promoting organisations maintenance. Allow for costs of initial Delay to Programme - Delay due to uncertainty in quality and management, monitoring and sustainability of habitat. This could lead to delayed agreement of HRA and maintenance ASEA Ecology Mitigation and Flood Defence Project
Table 3 Key Risks Consequence Mitigation Probability Cost Impact Cost Impact Time Impact WFD compliance. If adequate habitat cannot be provided, this could delay the main ASEA project or development within it. Cost - Resolution of any dispute may require change of the nature of the habitat, leading to increased costs 16 Insufficient natural supply of fresh water to Reputation - Disputes with NE over viability of consented habitat if Budget for purchasing, installation and M H VL wetland scrapes and ponds unmanaged could damage long-term relations between organisations. operation of pumps post-completion. The general public may become aware and this could manifest as criticism llow for costs of pumping, monitoring of the scheme and the promoting organisations and maintenance Delay to Programme - Delay due to uncertainty in quality and sustainability of habitat. This could lead to delayed agreement of HRA and WFD compliance. If adequate habitat cannot be provided, this could delay the main ASEA project or development within it. Delays as pumping arrangements designed and operation and maintenance regime is agreed. Cost - Resolution of any dispute may require change of the nature of the habitat or additional pumping and associated maintenance, leading to increased costs 17 Adequacy of proposed habitat as Reputation - Disputes with NE over effectiveness and overall area Take a cautious approach to viability of compensation is questioned by NE and provided of consented habitat if unmanaged could damage long-term habitat. Procure more than minimum others relations between organisations. The general public may become aware land area for habitat in case some of it and this could manifest as criticism of the scheme and the promoting does not establish properly. Budget for organisations post-completion purchasing, installation Delay to Programme - Delay due to uncertainty in quality and and operation of pumps sustainability of habitat. This could lead to delayed agreement of HRA and WFD compliance. If adequate habitat cannot be provided, this could delay the main ASEA project or development within it. Cost - Resolution of any dispute may require change of the nature of the habitat, leading to increased costs 18 Stakeholders demand for project to address Reputation - Disputes with stakeholders over effectiveness of defences Project cannot protect against groundwater flood risk could damage long-term relations between organisations. The general groundwater flooding due to naturally public may become aware and this could manifest as criticism of the permeable soils and likely obstructions scheme and the promoting organisations along defence alignment preventing Delay to Programme - Delay due to uncertainty in quality and sheet-pile cutoffs below defences. sustainability of flood defences. This could lead to delayed planning consent or commencement of construction. Cost - Resolution of any dispute may require change of design, leading to increased costs ASEA Ecology Mitigation and Flood Defence Project
Table 3 Key Risks Consequence Mitigation Probability Cost Impact Cost Impact Time Impact 19 Stakeholder feedback during detailed design Reputation - Disputes with stakeholders about finishes or appearance of Clarify uncertainties & scheme details M VH VL requires incorporation of more expensive project could damage long-term relations between organisations. The with NE, SGC, BCC, HE, IDB and defence-types, habitat types or general public may become aware and this could manifest as criticism of others, prior to commencing detailed accommodation works in order to gain the scheme and the promoting organisations design. Also plan for iteration of options approvals and consents, or to satisfy consent Delay to Programme - Delay due to need for redesign work and & re-working of some aspect conditions. Project is required to take on uncertainty as to whether the project will proceed if it cannot meet newly existing assets (eg. Cotteralls Pill) stated stakeholder requirements. Disputes could obstruct consenting, and thus delay commencement on site. Resolution may require additional design work and consultation. Cost - Delays in obtaining consents or in agreeing designs could cause increased design costs or construction costs of standing plant and labour. Cost of revised defence types could be more expensive. . 20 Design change to avoid archaeology or to Delay to Programme - Delay due to time taken to redesign the scheme to Undertake pre-planning geophysical M VH VL avoid heritage assets avoid archaeology or heritage assets. Disputes over requirements for surveys wherever possible. Additional additional investigation could obstruct consenting, and thus delay surveys may be required prior to commencement on site. Attempts to resolve disputes may require completion of the design for additional design work, data collection and analysis. Delay to programme construction. to prepare statutory EIA & planning application Cost - Delays in obtaining additional survey information, consents or in agreeing designs could cause increased design costs, survey costs or construction costs relating to alternative methodology. Cost due to redesign of options or appealing decision. 21 Need for extensive rock armour Reputation - Additional rock armouring would impact on the SPA, and Overtopping analysis indicates that rock L VH VL likely to be a cause of objection from environmental stakeholder. Disputes armour is not required. Remain alert to with stakeholders about finishes or appearance of project could damage potential changes in guidance. Allow for long-term relations between organisations. The general public may additional design and consenting costs. become aware and this could manifest as criticism of the scheme and the Also allow for cost of more expensive promoting organisations defences at embankments. Delay to Programme - Cost of additional rock armouring. Delay due to need for redesign work and uncertainty as to whether the project will proceed if it cannot meet newly stated requirements. Disputes could obstruct consenting, and thus delay commencement on site. Resolution may require additional design work and consultation. Cost - Delays in obtaining consents or in agreeing designs could cause increased design costs or construction costs of standing plant and labour. ASEA Ecology Mitigation and Flood Defence Project
Table 3 Key Risks Consequence Mitigation Probability Cost Impact Cost Impact Time Impact Cost of revised defence types could be more expensive. 22 Purpose of habitat areas changes to full or Delay to programme - delays caused by need to obtain additional funding Be vigilant to potential scope creep. M VH VL partial public access nature reserve. for additional visitor facilities Allow risk budget for additional Significant changes to footpaths Cost - Delays in obtaining consents or in agreeing designs could cause footpaths, parking, bird-hides, fencing, increased design costs or construction costs of standing plant and labour. water control structures, signage, Cost due to redesign of options. Cost of additional visitor facilities interpretation information, dog-waste bins, etc. 23 Increased footprint and changes to nature of Cost - Cost of specialist equipment to be procured by the project Allow budget for purchasing specialist VH M VL flood defences from existing arrangements mowing equipment increases maintenance and requires new specialist equipment to enable safe maintenance 24 NR unable to provide funding contribution Delay to Programme - If project is developed on the assumption that NR Allow for cost of all railway-related flood will make a contribution, and it does not, then this could lead to a funding defence works within the scheme, shortfall. NR is subject to a spending review cycle, and their planned study assuming no 3rd party funding from NR. into the Avonmouth and Severn Beach branch line is not due in this spending period. Cost - Cost of items due for NR contribution may need to be funded from the project. 25 Project is required to install piles from the Reputation - Disputes with NR could damage long-term relations between Clarify uncertainties & scheme details M VH VL railway due to environmental constraints. NR organisations. The general public may become aware and this could with NR, NE, SGC, BCC, HE, IDB and object to scheme proposals. Approval to manifest as criticism of the scheme and the promoting organisations others, prior to submitting formal work on NR land is initially refused. Effort Delay to Programme - Delay due to uncertainty as to whether the project planning application. Attempt to install and staff time to manage stakeholder will proceed. Disputes could obstruct NR technical approvals, and thus all defences from outside of railway engagement is higher than planned. Impact delay commencement on site. Attempts to resolve disputes may require land, thus minimising interface with NR. on contruction costs due to programme additional design work, data collection and analysis. Implement a staged or Iterative design delays and onerous conditions. Design Cost - Delays in obtaining consents or in agreeing designs could cause approach to ensure project is 'right-first- rework. increased design costs or construction costs of standing plant and labour. time' on submission of consent Cost due to redesign of options or appealing decision applications and at start of construction. 26 NR object to landward defence alignment Reputation - Disputes with Network Rail and others could damage long- Ongoing discussions with NR due to non-protection of railway term relations between organisations. The general public may become aware and this could manifest as criticism of the scheme and the promoting organisations Delay to Programme - Delay due to uncertainty as to whether the project will proceed. Disputes could obstruct NR approvals process and thus delay commencement on site. Attempts to resolve disputes may require ASEA Ecology Mitigation and Flood Defence Project
Table 3 Key Risks Consequence Mitigation Probability Cost Impact Cost Impact Time Impact additional design work. Cost - Delays in obtaining approvals or in agreeing designs could cause increased design costs or construction costs of standing plant and labour. 27 Rail network service disruption incident Cost - NR require EA to operate under a BAPA & APA, requiring EA to Project must enter into APA and BAPA provide insurance against NR incurring costs arising from the scheme agreements to enable work on or next to the railway 28 Track possessions / access Delay to Programme - There is inherent uncertainty in obtaining track Appoint a contractor / designer with possessions. NR reserve the right to cancel these experience of working in the rail Cost - NR will require the projet to pay for track possessions to allow industry, with rail safety and access construction works on or close to the railway. This often requires shift- planning specialists work and redundancy in personnel and plant to ensure effective handover at the end of the line possession 29 Land required for habitat not available for Reputation - Disputes with landowners could damage long-term relations Project aims to provide more habitat use or landowners/tenants make with client organisations. The general public may become aware and this area than the minimum recommended in unreasonable conditions on use as habitat. could manifest as criticism of the scheme and the promoting organisations the Cresswell Report. Includes risk of obstruction by manorial rights Delay to Programme - Delay due to uncertainty as to whether land at Northwick purchase or change in tenancy agreements will proceed. Disputes could obstruct technical and environmental approvals, and thus delay design stages or commencement on site. Attempts to resolve disputes may require additional design work, data collection and analysis. Cost - Delays in obtaining agreeing land purchase or tenancy agreements could cause increased design costs or construction costs of standing plant and labour. Land purchase costs could rise if parcels are treated as 'ransom' areas to make the project viable 30 Land access difficulties including Bristol Port Delay to Programme - Obstructed access could delay construction Early liaison with landowners. Issue M VH VL (access to works and procurement of site activities notice of entry. compounds) Cost - Delays could cause increased cost of standing plant and labour 31 Landowners demand design changes to suit Reputation - Disputes with landowners could damage long-term relations their requirements, possibly obstructing with client organisations. The general public may become aware and this access until agreement is reached. Eg. size could manifest as criticism of the scheme and the promoting organisations and height of defences, footpaths, Delay to Programme - Obstructed access could delay consenting, design landscaping, property access, views, and construction activities selection of materials Cost - Delays could cause increased cost of design and construction 32 Under-estimation of compensation budget for Cost - compensation may increase M VH VL construction-related or permanent provable ASEA Ecology Mitigation and Flood Defence Project
Table 3 Key Risks Consequence Mitigation Probability Cost Impact Cost Impact Time Impact losses 33 Unreasonable request for accommodation Disproportional impacts on Reputation, Cost, Delay to Programme works or compensation claim 34 Local source of suitable fill material cannot Cost - Additional cost of material and transportation from remote site. See L H VL be found or remote sources of material also item 5 above cannot be provided free from cost of transportation 35 Adequacy of Site Information. Project is Cost - Project costs may increase if risk has been undervalued or cannot M H VL unable to transfer risk to contractor be transferred 36 Loan from LEP is found not to be interest Cost - Value of interest added to project costs free 37 Basis of LEP or FDGIA funding award Reputation -delays to funding approvals could impact of reputation change Delay to Programme - Obstructed access to funding could delay consenting, design and construction activities Cost - Delays could cause increased cost of design and construction. 38 Project is expected to fund long-term Cost - Value of monitoring and maintenance added to project costs monitoring and maintenance of Areas 4 & 5 39 Waste management regulations change Cost - Value of additional monitoring and administration added to project costs 40 EIA regulations change, or need for strategic Programme - Delays to consents level EIA Cost - Value of re-work of environmental documents
Appendix H Avonmouth Severnside Enterprise Area (ASEA) Ecology Mitigation and Flood Defence Project December 2017
Summer 2017 Public and Stakeholder Engagement Period Summary of Feedback
Avonmouth Severnside Enterprise Area (ASEA) Ecology Mitigation and Flood Defence Project South Gloucestershire Council, Bristol City Council and the Environment Agency are working together to improve flood defences and create new habitats for important wildlife species. This project will help to ensure that economic development can continue within the Local Enterprise Partnership’s designated Enterprise Area without harming the environment. In addition, this work will also have benefits for the local community.
Purpose of this report During summer 2017 the ASEA project team published information outlining proposals for flood defence and habitat creation works in the Avonmouth and Severnside area. The purpose of this exercise was to provide everyone with an opportunity to comment prior to the submission of planning applications. This report provides an overview of the engagement activities undertaken during this period and the feedback received. It also explains how this feedback is being used to help shape the final proposals that will be used in the planning submission. Project context This project is focussing on managing flood risk along a 17km stretch of coastline from Aust to Avonmouth and aims to deliver a minimum of 80 hectares of wetland habitat to mitigate the impacts of development within the Enterprise Area. The study area falls partly within South Gloucestershire Council and partly in Bristol City Council. Background information on the project can be viewed at: www.insouthglos.co.uk/enterprise/avonmouth/flood-ecology/ Engagement activities undertaken Between 20th June and 8th August 2017 the following specific engagement activities were undertaken: - Information outlining the proposals for both flood defence works and the creation of habitat areas was published on the project website. This included: - A series of display posters (reproduced within Appendix A) which explained the required height of the flood defences and the proposed method of construction. For the habitat areas details of the current area and works required were included. - Artist’s impressions showing how the flood defences could look.
Avonmouth Severnside Enterprise Area (ASEA) Ecology Mitigation and Flood Defence Project December 2017
- Cross-sections providing technical details, such as the heights of the current and proposed flood defences. - Short three-dimensional animation videos showing how the defences would relate to the existing landscape in key areas. - An interactive mapper, bringing together all of the above information. - Two public exhibitions were held, in Avonmouth (within Bristol City Council area) on 4th July 2017 and in Severn Beach (within South Gloucestershire Council area) on 18th July 2017. - Stakeholders, landowners and members of the public were directed to the website, and invited to attend the public exhibitions via emails, newsletters, direct mailouts, local media, social media and posters. Copies of the project newsletter, exhibition materials and feedback forms were also placed for reference in Avonmouth Library. - The project team attended seven community, parish and forum meetings across both the Bristol City Council and South Gloucestershire Council areas to explain the project and to answer questions (these meetings followed a number of initial briefings and presentations held during 2016/17). - A meeting was held with residents at New Passage specifically to discuss proposals close to their properties. A follow up meeting was also held in September. - Feedback was invited via a bespoke feedback form (included in Appendix A) or by email. Scope of engagement The nature of the project and current stage of work meant that this phase of engagement was focussed on specific issues. The project team was keen to clearly explain which elements of the proposals could, at this stage, genuinely be influenced by feedback. The feedback requested focussed on detailed issues, and the project team was particularly keen to understand how the proposed works would impact on individuals. Feedback was not requested in relation to: - The position/alignment of the flood defences as a ‘hold the line’ approach has been decided through previous work (see the FAQ section of the webpage for details). This position seems to be well understood by residents and stakeholders. - The required height of the flood defences as this has been established using detailed computer modelling, taking account of predictions of sea level rise. A number of questions were nevertheless raised on this topic and the project team has sought to further explain the technical work underpinning these predictions. - The type of flood defence (wall, bank etc) as technical constraints have dictated the required form, and as a general rule flood banks have been proposed unless precluded by space/habitat constraints. However, during the engagement period it became clear that some residents had concerns over the proposals at specific locations and, as a result, some elements of the proposals have been reviewed, to take account of feedback (see below).
Avonmouth Severnside Enterprise Area (ASEA) Ecology Mitigation and Flood Defence Project December 2017
Level of response received During the engagement period: - Around 25 people attended the Avonmouth event. - Around 60 people attended the Severn Beach event. - 42 emails and feedback forms were submitted. - The presentations given by team members at the various community meetings were well attended by Councillors, residents and stakeholders. - Meetings held to discuss the issues at New Passage were well attended by residents directly affected by the proposals. Feedback received Flood defence proposals During the engagement period a wide range of constructive discussions took place and have helped to evolve and improve the proposals. Generally there was a good degree of acceptance that improved flood defences are required, and a number of respondents were grateful that the proposals would offer both property and land a greater degree of protection into the future. However, there were some concerns and questions around some aspects of the proposals. The proposals to install a sheet pile flood wall in the New Passage area were the subject of the greatest number of comments. Here, residents expressed serious concern that the proposal would be unacceptably visually intrusive, significantly impact on views out to the estuary, have a negative impact on wildlife/habitats and prevent access to the coastline. A meeting was held with residents to address these issues and a revised proposal has been worked up, taking account of their feedback. Other concerns were raised in relation to the flood defence proposals in terms of: - Impact on the landscape and wildlife as a result of the loss of poplar trees and hedgerows. - The potentially stark appearance of raised concrete flood walls and the risk of damage and graffiti. - Impact on access to the coastline, for example for recreation and fishing. - Volume and routeing of construction traffic, particularly considering the volume of material that would need to be brought in to create the raised embankments. Table 1 provides an overview of the comments in relation to the proposed flood defence works. It seeks to provide a general feel for the type, nature and strength of comment received therefore, responses are grouped and presented in summary format. Table 1 explains how each comment has been considered by the project team and the extent to which design changes have been made to address the issues raised.
Avonmouth Severnside Enterprise Area (ASEA) Ecology Mitigation and Flood Defence Project December 2017
Habitat area proposals The proposals for the creation of wetland areas attracted fewer comments compared to the flood defence works. There was clear support for the principle of improving habitats and supporting the species of the Severn Estuary. Some respondents raised questions about the proposed location of the wetland areas and a number of residents were concerned about the volume of construction traffic, the movement of materials and the impact on current farming practices. Table 2 provides an overview of the comments received and sets out how these have been considered within the evolving design and planning. Overarching comments A number of the comments made related to the project as a whole. These are summarised in Table 3. Design changes made in response to feedback In response to the feedback received a number of amendments have been made to the proposals to help ensure that they address local issues and concerns. These include: - A redesign of flood defence proposals for the New Passage area, introducing glass panels above a low concrete wall to help reduce the visual impact and ensure that views out to the estuary are largely retained. These proposals have been discussed with residents and have been well received. - Alterations to the proposed materials/colour for the concrete flood wall at Avonmouth. In addition, ongoing work is looking at: - Consideration of alternative flood defence options to help mitigate impact on the poplar trees adjacent to the landfill site at Northwick We have prepared a short report outlining the issues and options we have considered. This is available on our webpage. - How best to ensure the proposals are fully accessible to all. Next steps Over the coming weeks the designs for the flood defences and wetland areas will continue to evolve in response to the feedback received, ongoing stakeholder discussions and emerging technical work. We hope to be in a position to submit planning applications to Bristol City Council and South Gloucestershire Council at the start of 2018. As part of the normal planning application process residents, communities and stakeholders will have another opportunity to review the amended proposals and comment should they wish. Once planning consent is granted we hope that works can be delivered in phases, with the earliest preparation works starting on site in 2018/19. For future updates on the project please visit: http://www.insouthglos.co.uk/enterprise/avonmouth/flood-ecology/. Please send comments or queries to: [email protected]
Avonmouth Severnside Enterprise Area (ASEA) Ecology Mitigation and Flood Defence Project
Table 1 – Comments and responses: flood defence issues
Location/Topic Comment Response Northwick Query whether managed realignment has been We did consider managed realignment for this section and are proposing around 1ha of considered for the Northwick area. additional coast habitat via realignment of the bank near Cake Pill. However, there are relatively few opportunities for realignment in the majority of the scheme due to existing infrastructure, commercial and residential development and legacy land use issues. The scheme is aligned with the ‘hold the line’ approach set out in the Severn Estuary Strategy. Concern regarding the impact of the flood Our proposals will protect the landfill site at Northwick from flooding. While the defences are defence proposals on the land fill at Northwick lower than existing high ground, provision of raised flood embankments will protect the material contained within the landfill site. Strong concern from several residents about the In response to concerns about the removal of the poplar trees we have undertaken further work proposed removal of poplar trees adjacent to the to explore additional flood defence options and re-assess the constraints in this location. We landfill site at Cake Pill. These are felt to be an have prepared a short report outlining the issues and options and this is available on our important feature of the local landscape and a webpage. In summary, the options we have considered include: valuable habitat for wildlife. - Realigning the flood defences seaward of the trees. This would cause the flood defence embankment to encroach onto the intertidal marsh of the Severn Estuary, which has multiple national and international protective designations including being designated a Special Protection Area. As such, planning permission would be unlikely to be achieved. Site walkovers have been undertaken with Natural England to consider these issues, - Realign flood defences landward of the trees. This would encroach into the landfill site. It is highly likely that working in this area will disturb contaminants and therefore significant mitigation measures will need to be included in the design to avoid causing pollution. - Change flood defence type. We have considered using a sheet piled or concrete flood wall as an alternative to an embankment. A wall could have a potentially negative visual impact on the area and the foundations required could damage the existing poplar tree roots. - Current alignment, but with localised encroachment into the intertidal marsh. We have considered a variation which would allow the embankment to encroach into a triangle of drier intertidal marsh at the northern end. This area of land had previously been designated to provide an enhanced habitat for wading birds and is the only area of land within the scheme area that is available for this type of improvement. At this time, and based on current information, the original flood defence option presented to the public in Summer 2017 is preferred because it is acceptable under the Habitats Directive, minimises risk of erosion to the landfill site, minimises land take, avoids slow die off of the poplars, provides for new native planting and retains the use of visually softer earthwork embankments. Any proposal would be subject to obtaining planning consent and we will continue to work with South Gloucestershire Council, as Local Planning Authority, to ensure our proposals are likely to be accepted.
Avonmouth Severnside Enterprise Area (ASEA) Ecology Mitigation and Flood Defence Project
Location/Topic Comment Response Concern that the flood defence proposals The proposed flood defence embankment between New Passage and Aust will require the require the loss of ancient hedgerow. removal and replacement of existing hedgerow. We will consider translocation of some of the more valuable, species-rich lengths of hedge from the existing position – this involves coppicing the hedge then scooping it up into a trench on the new boundary line – which has the advantage of regenerating much more quickly. Recognition that the Pilning wetland area has The success of the Pilning wetland area is recognised and this project seeks to complement that. been really successful. Concern that the flood We will continue to work with the landowner to ensure our proposals are compatible with the defence works will affect the existing Pilning existing success of the wetland area. wetlands area by bringing more people beyond the settlement boundary of New Passage and within closer proximity/increasing disturbance to wildlife. Concern that proposals affect lines of sight, breeding and roosting sites. North of New Concern that footpaths are to be set back on a The aim of the lower level is to help minimise the disturbance to birds on the estuary caused by Passage lower level (rather than along the top of the moving people. The lower level means people can still see over the crest to the estuary. People embankment) and that this will impact on walking will be encouraged to use the lower level through the use of information signs. enjoyment of walks and views. New Passage Query about why the height increase required at The height proposed at New Passage takes account of forecast increases in sea level due to New Passage is so high. Whilst improved flood climate change and also includes other factors relating to coastal environments including wave defences are generally welcome there is a action, storm surges and foreshore surface conditions. Contingency is built into the scheme to concern that the proposals are very high. ensure the defence can withstand a 1:200 year scale event for decades into the future. Concern that the height proposed at New Our sea level rise calculations are based on national guidance for the impacts of climate change. Passage is based on uncertain predictions of This guidance is based on the results of significant scientific research. Our aim to provide tidal sea level rise and that there is no economic flood protection for at least 60 years is in line with current guidance. need for 60 years of protection. Concern that there are existing drainage issues The Environment Agency is aware of this issue and is investigating possibilities for addressing at New Passage which require attention to this either as part of the ASEA project, or separately through joint working with the South prevent water diverting off the existing ramp and Gloucestershire Council highways and drainage team. pooling in adjacent gardens. Query about why the solution for New Passage A flood wall is proposed at New Passage because there is limited space in this location. is proposed to be a wall rather than an An earth bank of the height required would mean widening the base by up to 10 metres. We embankment. General feeling that an cannot construct any works on the seaward side of the current footprint of the defences, as it embankment would be more appropriate or that would encroach on the Severn Estuary area, which has multiple national and international this section should be seen as a transition protective designations, Therefore in this area an embankment would encroach significantly into section between the wall at Severn Beach and resident’s gardens. This option was therefore discounted. the embankment at Northwick. A wall provides a slimmer foundation and potentially less disturbance during construction.
Avonmouth Severnside Enterprise Area (ASEA) Ecology Mitigation and Flood Defence Project
Location/Topic Comment Response The published proposals showed a sheet pile flood wall. However, following discussions with residents a revised proposal has been drawn up and this includes a dwarf wall with a reinforced concrete foundation, with glass panels above (see below). Preference for a rock armour/revetment option A rock armour and revetment option was identified in previous studies as an option for the area coupled with raising of the embankment between Aust and New Passage. However, this work did not go down to the geographic scale of between New Passage and Chestle Pill as considering what was required specifically for the New Passage to Chestle Pill area. identified by previous studies. This project is now looking at the design in much more detail both geographically and using new hydraulic modelling than previous more broader scale studies. Based on this a rock-armour and revetments solution would not be appropriate. Rock armour and revetments are typically used in locations where there is known to be significant wave action. As the New Passage and Chestle Pill area is relatively sheltered and protected by a long, shallow-sloped salt-marsh run-up, rock-armour and revetment have been ruled out due to reduced wave action applying to this section. In addition, the hard finish of rock armour and revetment may be considered to have an adverse impact by encroaching into the Severn Estuary designated area
Significant concern was raised by multiple A residents meeting was held on 7th August 2017 to discuss the proposals for New Passage. This residents around the proposal for a sheet piled was organised by local residents and was attended by the ASEA project team. flood wall at New Passage. The meeting was very positive. It was a constructive discussion that helped the project team to Detailed comments were submitted regarding understand local concerns and provided an opportunity to work with residents to identify practical the impact to individual properties. solutions to overcome these concerns. Concerns were also raised by Severnside CEF At the meeting design options were openly explored. A number of design iterations were and Severn Beach Parish Council. suggested by the project team that could help to address local concerns and the pros and cons of The detailed concerns raised in relation to the these were debated. The outcome was a general consensus that, given the practical constraints, initial proposal shown in the public engagement a glass panel flood defence parapet above a dwarf wall would be a preferred solution. materials are set out individually below In response to these comments an alternative design proposal was drawn up. This is includes a dwarf wall, with glass panelling above. The ways in which this solution addresses specific concerns are explained below. The revised design was discussed with New Passage residents at a second meeting on 27th September 2017. The response was very positive and residents felt that this was much preferable to the original proposal. Visual impact – a sheet pile solution was These issues were discussed in detail at the residents meeting. considered too imposing. The design of the In order to reduce the overall impact of the defence on the landscape a revised design wall, as shown in the artists impressions, was incorporating glass panelling has been agreed with residents. The importance of keeping the felt to not be in keeping with the local landscape. framing of the glass to a minimum in order to further reduce visual impact, is noted. A softer, greener solution would be preferred.
Avonmouth Severnside Enterprise Area (ASEA) Ecology Mitigation and Flood Defence Project
Location/Topic Comment Response A number of suggestions for alternative designs Further work is required to identify appropriate materials and render – this could be designed to and mitigation were submitted including a blend in with adjacent properties. Overall this revised design will have a lesser visual impact. curved wall, various terraced structures, soil Visual impact will be considered in detail within the Environmental Impact Assessment. banks to conceal the wall, and use of planting or The extent to which the proposals are acceptable within the Green Belt is being considered as green paint to reduce visual impact. part of the Planning Statement that supports the Planning Application. It was suggested that the sheet pile solution was not appropriate within the Green Belt (in terms of openness and visual amenity), AONB and SSSI. Impact on views out to the estuary and into the This glass panel solution will ensure that users of the footpath can still enjoy views out to the Pill – there was concern that the concrete wall estuary. would prevent people (particularly those in wheelchairs) enjoying the view from the Public Right of Way). Impact on access to the coast - in terms of The importance of retaining access to the coastline is recognised. provision of gates/gaps in the defence, and There will be a flood gate included at the top of the current access ramp to the foreshore at New potential difficulty of access for people with Passage. This will only be closed during periods of high tide. Similar solutions are proposed for mobility impairments. other locations along the 17km stretch. Our designs will comply with all relevant design standards. Impact on habitat and wildlife - including Where not directly in the footprint of a new hard flood defence structure, all grassland areas meadow grass, bee orchids and bats. disturbed by construction activities will be reinstated to their original condition. We would delay cutting grass in this area until September each year in order to protect the wildlife. In order to preserve the flower species in this area, we will retain the top soil and put it back post-construction where disturbed. Our Environmental Impact Assessment will consider the impact of our proposals on other habitats and species, including bats. Impact on access for ongoing maintenance – for We are still assessing what would be the most appropriate access route for ongoing example, to service the tidal outfalls at Chestle maintenance once the new flood defence scheme is completed. For the section between New Pill and Cotterall Pill. Passage to Aust, we are aiming to improve access from both ends; at New Passage and Cake Pill. We also need to have access to the new flood gates we are proposing and be mindful of land ownership and setup access agreements where necessary. Concern around volume and routeing of traffic We have been seeking advice from a construction company to identify appropriate access during construction. Suggestion that access routes. This will include looking at options to gain access across farmland. There are a number should be via farmland. of route options being considered, including access from the A403, down from Cake Pill and a Concern particularly about impact to New route off New Passage Road. The route will depend on the load limits of Chestle Pill. We are Passage Road.
Avonmouth Severnside Enterprise Area (ASEA) Ecology Mitigation and Flood Defence Project
Location/Topic Comment Response sensitive to the impact access may have on residents and will be looking at how we can mitigate these impacts, for example by restricting access times and routes. To minimise the impact of construction traffic generally across the study area we will re-use materials where we can. We will use a supply chain well known for considerate construction, we are looking at potential to bring material in by train. In respect of the revised designs discussed at These comments have been considered in detail and are, where possible, reflected in the re- the New Passage residents meeting the worked designs for New Passage. This design incorporates glass panels and we will reflect following comments were subsequently preferences for materials where possible. received: The re-worked design includes a 5m access width (as opposed to the 3m requested) as this is - Preference for wall and glazed panel the width required by the Environment Agency for maintenance works and access. solution - Preference for lower footpath - Preference not to have handrails - Preference for narrower 3m access road, with passing places to reduce impact - Consolidated gravel finish to the path is preferred over tarmac - Preference for a rubble to stone façade to the wall would be better than solid concrete Severn Beach Concern that the Binn wall at Severn Beach is Hydraulic modelling and design has been undertaken to latest national standards, accounting for not proposed to be raised. Concerned that with 60 years of predicted sea level rise to account for the life of the enterprise area. The modelling no height increase Severn Beach will become shows that the existing defences at Severn Beach are already at the required defence level but the area most likely to flood in the future. may require some strengthening/reinforcement. Request for the ramp at New Passage to remain This ramp will be retained with a flood gate installed across the opening and there will be no due to life boat usage. restricted lifeboat access. Generally positive comments about the Positive feedback here is appreciated. proposals to raise the defence and improve the footpath to the south of Severn Beach (as shown in the artist impression). Severn Beach Concern that the proposals do not offer We are working with Network Rail to combine the flood defence with the railway line, but if that rail line protection to the railway line. Preference for the can not be achieved, we will revert to our current solution of going landward of the rail line. We flood wall to be located to the seaward side of will seek planning consent for our current solution to demonstrate that a full defence can be the railway line, so as to provide protection to provided even if Network Rail do not wish to have the defence on Network Rail land. This is infrastructure. important for secure funding for the whole scheme.
Avonmouth Severnside Enterprise Area (ASEA) Ecology Mitigation and Flood Defence Project
Location/Topic Comment Response Improvements to the footpath alongside the Our proposals already include for improvements to this footpath. railway would be appreciated. Avonmouth Concern over the proposed appearance of the The project team acknowledges that the images shared were very indicative. Comments about concrete flood wall at Avonmouth and impact on the colour and materials of the wall at Avonmouth are noted. Whilst there are very few publicly views into Avonmouth from the port/cruise accessible viewpoints affected by the wall the project will seek to use appropriate materials to ships. make the wall blend into its surroundings. Query about what the proposed sheet piles at The sheet piles would be close to the railway line and not obscure the view from the paths. The Lamplighters Marsh would look like and whether sheet piles would be unclad, but the retained vegetation would screen views to the sheet piles. views of the River Avon would be obstructed There is potentially an opportunity to plant more vegetation to screen the sheet piles from the public footpath at Lamplighters Marsh. Concern that land at Lamplighters Marsh is not At Lamplighters Marsh we have aligned the defences along the boundary next to the railway, so protected by the proposed works. that we are protecting the railway, the dockyard, and other residential property in Avonmouth. This alignment also helps to minimise impact on the Lamplighters Marsh Nature Reserve. We will be ensuring that the ASEA scheme does not increase flood risk to Shirehampton by testing the proposed scheme within hydraulic modelling. Concern that parts of Shirehampton (Station Whilst an upgrade or alteration to defences in this location are not part of this project the Road and Wellington Mews) are not protected Environment Agency and Bristol City Council will be investigating their performance as part of a by the proposed works. separate project and will update the community as plans progress. Some concerns about groundwater flood risk at Groundwater issues are largely outside the scope of this project. The Bristol City Council Local Avonmouth. Flood Risk Management Strategy has an action to undertake a citywide groundwater flood risk assessment and will include the above in such assessment Ecology Concern that the proposals will impact on the We are seeking to do no works on the protected areas. Works will be on the landward side in saltmarsh and that coastal squeeze will reduce order to not impact the protected area. We are working with Natural England in developing and the area of saltmarsh. Notes that the wider implementing the scheme. Coastal squeeze is being addressed elsewhere in the Estuary by the impact on the saltmarsh should be considered. Environment Agency. Concern over ability of ground dwelling wildlife These issues, and potential mitigation measures, are being considered as part of the to pass over large vertical structures. Environmental Impact Assessment. Public rights of Query around extent to which the proposed The project team is aware of Natural England’s project to establish the England Coast Path on the way (PROW) flood defence works are consistent with Severn Estuary and has received detailed feedback from Natural England as part of this ambitions to for the proposed English Coast engagement process. We will continue to work together on the interface between our projects. Path National Trail. The proposals must meet the requirement of the We are aware of these requirements. The project will seek to provide suitable access for all. We Equalities Act 2010, the Marine and Coastal are working with Natural England to ensure the project is aligned with their vision for an England Access Act and the Fieldfare standards for all. Coast Path. Detailed comments received about the
Avonmouth Severnside Enterprise Area (ASEA) Ecology Mitigation and Flood Defence Project
Location/Topic Comment Response requirements for gates/structures, gradients and need to retain views for people in wheelchairs. Various comments about the extent to which These comments are noted. At this stage the project is unlikely to change the status of the path, improvements to the Public Rights of Way which is a public footpath, not a bridleway should cater for multi user groups – wheelchair access, cyclists and horse riders. Suggestion that interpretation information The value of interpretation panels, in helping to provide information about local wildlife and should be included along the coastal PROW. heritage is acknowledged and appropriate information will be provided where possible. Access Concern around likely disturbance caused by It is inevitable that such a large construction project will introduce additional traffic to the network. site working. In particular, concern that This matter will be covered in the Environmental Statement. For example, we are working with transportation of materials to create the raised construction experts to identify likely temporary access routes from the A403 to avoid impacting embankments will be difficult – large volumes of local lanes and streets in the New Passage area and at Aust. materials, narrow roads etc. Concern to ensure that future access for We are aware of individual concerns about previous access for maintenance over private land and maintenance is not across private property. have passed these to the appropriate maintenance teams. Our proposals for future access will not rely on access over private land. Flood Query whether the flood defence works will The proposed scheme will be subject to its own Flood Risk Assessment (FRA) as part of the risk/drainage increase flood risk outside of the Enterprise planning application process. The FRA process will ensure that the scheme has no negative Area. Some concern was expressed about impact on flood levels elsewhere. flood risk for example to the areas north of the M48. Concern that proposals will adversely affect We are working closely with the Lower Severn Internal Drainage Board to ensure that our flood risk and lead to increased risk of flooding proposals are acceptable. We are also modelling our proposals to ensure that they do not increase from the rhines, due to blocking of internal flood risk elsewhere. drainage. Keen to ensure drainage ditches along the sea Our proposals will incorporate appropriate drainage. walls are reinstated. General/other Query raised about if/how the ASEA flood Our modelling will be reviewed by experts within the IDB. models would be subject to third party review. Concern that flood walls would be subject to Concerns are noted. Where possible we will look to use anti-graffiti surfaces, graffiti/damage Important to ensure that access to the coastline Our proposals will not restrict access for fishing. The embankments will still allow access, albeit is retained for fishing. that there will be a need to cross a higher bank. Where flood walls are proposed, gates will be incorporated to ensure access is retained.
Avonmouth Severnside Enterprise Area (ASEA) Ecology Mitigation and Flood Defence Project
Location/Topic Comment Response Have long term maintenance/management Yes, long term maintenance/management costs are included within our cost estimates as sums costs been taken into account? that support our funding bid. Concern that increased protection from flooding The area will remain in the flood zone as defined on the flood map for planning. For brand new will encourage additional residential development, the planning process requires a Sequential Test to first be passed whereby development. alternative sites outside of the floodplain must be considered. This involves the Local Planning Authority (LPA) needing to agree there is a genuine need for new residential development within the floodplain. and both Local Authorities have confirmed there is no strategic policy for residential development in Avonmouth and Severnside. In addition, the flood defence proposals will provide protection from 60 years’ worth of climate change based on the latest planning guidance, which is sufficient for commercial development but residential development would require a 100 year climate change scheme. Concern that the increased protection from The objective of the scheme is to help realise the potential within the Enterprise Area – the extent flooding will encourage additional/inappropriate of which is already defined and agreed through various policy. The majority of landholdings to be levels of commercial development. developed are in private developer ownership and benefit from the extant 1957/58 consent. As such, sites will come forward for development as and when the developer either completes a commercial deal with an occupier or, takes forward a development on a speculative basis. Those that are not covered by the extant consent, would need to apply for planning permission in the normal way.
Avonmouth Severnside Enterprise Area (ASEA) Ecology Mitigation and Flood Defence Project
Table 2 – Comments and responses: habitat creation issues
Comment Design response Queries about why land adjacent to the existing Pilning Wetland The project cannot force landowners to give up their land or make them re-use it as wetland. Land Area is not being utilised for the habitat areas. Suggests that using is being acquired through negotiation and to incorporate this land into the scheme and any planning this area would create habitat areas that are better connected application without consent from the owners would carry an unacceptable risk. (avoiding the A403 acting as a barrier for birds) and would also provide a source of materials for the creation of embankments (and reduce the need to bring in material). Concern that proposals will lead to a loss of farming land or will Our project aim is for the land, except that used for permanent ponds, to remain in active farming impact on current farming practices. Request that scrapes have use as grazing land. Our designs include for shallow side slopes to the scrapes. shallow slopes to allow for the movement of farm machinery and to reduce the chance of poaching by cattle. Concern that proposals will affect flood risk due to the blocking of Our proposals are designed to increase wetness in only the fields we have acquired for wet internal drainage. Suggests additional pumping stations and grassland habitat, without affecting the main drainage rhines. We are working closely with the sumps should be provided to mitigate extra risk. Internal Drainage Board to ensure that our proposals are acceptable. We are also modelling our proposals to ensure that they do not increase flood risk elsewhere. Keen that habitat areas are seen as assets. For example they We agree the scheme should create spaces and infrastructure that we can all be proud of Details can help attract businesses and improve the environment for local of access will need to be agreed with the organisation that eventually take on responsibility for employees. Feeling that positive use of the habitat areas should maintenance of the wetland areas. At this stage, we envisage that public access is unlikely to be be encouraged – e.g. health walks. encouraged. However, access along the Severn Way will remain public so users of the public right of way will benefit from improved local habitat.
Comment that there needs to be some commitment to the Part of our project is to establish a management regime for the habitats and, in due course, we will management of the habitats be talking to organisations that may take on a management role. Concern that the proposals are not ambitious enough and that 80 hectares is the minimum required amount of compensatory habitat, as specified by previous extra effort should be made to compensate for wildlife lost to studies. Where possible we are looking to provide additional habitat. industry. Query about whether the wildlife areas will have buffers, to The project does not have the ability to prevent future uses on adjacent land causing disturbance. prevent future uses up to the boundary and causing a disturbance.
Avonmouth Severnside Enterprise Area (ASEA) Ecology Mitigation and Flood Defence Project
Comment Design response Suggests that proposals should allow for visual access to new The existing public rights of way are being retained and therefore it will still be possible to look out wetland areas – to allow recording etc of species. across the habitat areas. Concern that proposals represent an expedient answer not the The proposals for habitat creation focus on land where we can be most certain that we can reach best answer (e.g. focus on land owned by the Council rather than an agreement with landowners to acquire the land in a reasonable time scale. other sites) Comment that replacement of hedges should not just be at the Where possible we will ensure that hedgerows are replaced as part of this project and have identified discretion of landowners. areas for replacement scrub planting within the project proposals. Beyond that replacement of hedges will be at the discretion of the landowners, but we intend to work closely with them to encourage appropriate replacement. Comment that proposed lakes should be dug deep with graduated The proposed ponds will incorporate a deeper area with steep sides which will permanently hold sides to ensure they do not dry out and to provide plenty of water, as well as shallow margins. margins for foraging. Could we use Northwick habitat land as a kind of sustainable In principle wetland habitat areas could be used in this way. In this instance our view is that this urban drainage system (SUDS) for excess water in the main rhine would not be practical as the habitat area is downstream of the perceived flooding problem at to alleviate flooding in Aust. Aust. SUDS only really helps reduce flood risk to property downstream of the SUDS facility. However, if the community can provide any information on flooding problems in the Aust area we
can review this in more detail.
Avonmouth Severnside Enterprise Area (ASEA) Ecology Mitigation and Flood Defence Project
Table 3 – Comments and responses: overarching issues
Comment Response Concern that the proposals are already ‘fixed’ and that there is As part of this information sharing exercise we have been keen to manage expectations. The limited opportunity for influence or full consultation. alignment of the defence, the height required and (to a large extent) the type of flood defence (bank or wall) have been dictated by previous studies and a number of important technical and practical constraints. Therefore we have sought to open about the extent to which these can be influenced. The purpose of this engagement period was to listen to and understand everyone’s views. Where significant concerns have been raised we have listened to feedback and revisited designs. For example, we have worked closely with the residents of New Passage to agree a solution which meets the requirements of the community. Request that the Environment Agency engages with local As the project moves forward to procurement the Environment Agency will be keen to explore businesses when allocating works as this will have a positive options to engage local businesses. impact on the local economy. Concern that meeting with New Passage residents was not The two residents meetings held have been planned and organised by the local community and advertised to all. attended by the Environment Agency. If anyone who didn’t attend these sessions would like to be notified of future meetings we would be pleased to hear from you. Details about the proposals were sent by direct mailout to all residents of New Passage. Concern that the LEP funding for this project could be used on The LEP funding, agreed via the city growth deal, is associated with new business rates only (i.e. other public services, which arguably would provide a greater new businesses brought online in the defined boundary for ASEA). These developments cannot go benefit to the community. ahead unless our project delivers the necessary mitigations. There will be no new money to use on other things (raised via business rates) unless the development is first unlocked by our scheme.
Query over how land raising of sites in the ASEA is managed Due to the provisions of the extant 57/58 area, the only way we can sustainably put a halt to the land raising is by providing better flood defences. Concern that the Councils are not appropriate to determine the Across both BCC and SGC there are different roles. Some officers are involved in progressing the planning applications because they are perceived to have a project and promoting the scheme. Others are involved in the consenting process. The team has vested interested interest in the project. been mindful of the need to ensure that these two functions remain separate to enable the applications to be considered in the appropriate way. All contact with the consenting function of the planning authority has been made through normal pre-application processes.
Appendix A: Display Boards and Feedback Form