Commercial in Confidence

Swansea Gypsy and Traveller Project Flood Consequences Assessment: LDP Deposit Plan Allocation - Land off Pant Y Blawd Road, Morriston Final Report April 2018

Quality Management

Quality Management

Job No CS/091654

Project Swansea Traveller Sites - Flood Consequences Assessment

Location Swansea

Title Swansea Traveller Sites - Flood Consequences Assessment – Final Report

Document Ref 001 Issue / Revision 001

File reference

Date 01/05/2018

Prepared by 1

Audrey Despinasse

Signature (for file)

Checked by

Kevin Hemmings

Signature (for file)

Authorised by

Daniel Stansfield

Signature (for file)

Revision Status / History

Rev Date Issue / Purpose/ Comment Prepared Checked Authorised

1 21/09/2017 Final Scoping Report AD KH DS

2 01/05/2018 Final FCA Report MDS KH DS

Executive Summary

Contents 1. Executive Summary 5 2. Introduction 6 2.1 Scope of Assessment 6 2.2 Description of the site 6 2.3 Local geology 8 2.4 Soil classification 8 3. Policy and Guidance 9 3.1 Flood and Water Management Act, 2010 9 3.2 National Flood and Coastal Erosion Risk Management Strategy,

November 2011 9 3.3 National Planning Policy and Advice on Flood Risk 10 3.4 Swansea Local Development Plan, July 2016 11 3.5 Caravan Sites and the Control of Development Act, 1960 12 3.6 Relevant Gypsy and Traveller Planning Guidance 13 3.7 Swansea Local Flood Risk Management Strategy, February

2013 13 3.8 Western Wales River Basin District Flood Risk Management Plan,

December 2015 14 3.9 Ogmore to Tawe Catchment Flood Management Plan, 2010 15 3.10 City and County of Swansea Flood Risk Management Plan,

2015 16 3.11 Multi Agency Protocol for flooding incidents at Lower Swansea

Valley. SWLRF Community Level Multi-Agency Response Plan (March 2014) 16

3.12 Strategic Flood Consequences Assessment (Stage 1: 2010) 17 3.13 Strategic Flood Consequences Assessment (Stage 2: 2012) 17 3.14 The SuDS Manual (C753), CIRIA (2015) 18 3.15 Welsh Government SuDS Guidance, December 2016 18 3.16 Climate change allowances 19 4. Sources of Flood Risk 20 4.1 Historical Flooding 20 4.2 Flood Risk from Rivers and Sea 20 4.3 Flood Risk from Groundwater 25 4.4 Flooding from Surface Water 25 4.5 Flooding from Artificial Sources 25 4.6 Flood Warning and Alerts 26 4.7 Residual Flood Risk 27 5. Development Planning Considerations 29 5.1 General Development Considerations 29 5.2 Justifying Location of Development 29 5.3 Proposed Design Plan 30 5.4 Fluvial Flood Risk Considerations 32 5.5 Surface Water Flood Risk Considerations 39 5.6 Other Flood Risk Considerations 39 6. Summary and Conclusions 40 Appendices 42 Appendix A 43

Executive Summary

Figures Figure 2-1: Location map of proposed site 7 Figure 4-1: Historical flooding extents recorded in the vicinity of the

site 22 Figure 4-2: Flood zones map showing flood risk from rivers and the

sea 23 Figure 4-3: Flood defences present in the vicinity of the site and the

area benefiting from them 24 Figure 4-4: Flood warning and flood alerts areas recorded in the vicinity

of the site 28 Figure 5-1: Proposed design for pitches within sub-areas 1a and 1b 31 Figure 5-2. Possible signage. 33 Figure 5-3. The proposed evacuation route 34 Figure 5-4: Maximum Depths provided by the model for a 0.1% flood

event 35 Figure 5-5: Maximum Depths provided by the model for a 1% flood

event 36 Figure 5-6. Maximum depths provided by the model for the 1% AEP

with 25% climate change allowance event. 37 Figure 5-7: Flood propagation in the 0.1% AEP event at sites 1a and 1b

from 7.25 hours to 8.50 hours. 38

Executive Summary

1. Executive Summary

Site Name Land off Pant Y Blawd Road, Morriston

Location Pant Y Blawd Road, Morriston

Client City and County of Swansea Council

Grid Reference SS6797/SS6798

Area (m2) 6,646 both sub-areas 1a and 1b

Current Use Concrete (1a) and Grassland (1b)

Natural Resource Wales Flood Zone Classification

Flood Zone 2 and 3 across the entire site

TAN15 Development Classification

Zone C1 within the entire site

History of Flooding Two historical flood records for site (before defences implemented).

Flood Defences Present along the western part of proposed site

Summary of Risks

Fluvial - Risk of flooding in the event of defence breach or overtopping. Residual flood risk in excess of 1 in 100 year plus climate change return period. Tidal - None Artificial Sources- None Groundwater- None Surface Water- Low to High risk in a minor part of the site.

Introduction

2. Introduction 2.1 Scope of Assessment 2.1.1 Capita have been commissioned by the City and County of Swansea Council (CCS) to

undertake a Flood Consequences Assessment (FCA) of the land allocated for Gypsy and Traveller accommodation in the Deposit Local Development Plan (LDP). The allocated land under Policy H 6 of the Deposit Plan is located off Pant y Blawd Road, Morriston.

2.1.2 The purpose of this Flood Consequences Assessment is to provide a thorough assessment of the flood risk to allow CCS to make an informed decision about the development of the site. This report considers flood risk from all sources (fluvial, tidal, groundwater, surface water and artificial sources), using the existing information available. Potential flood mitigation methods have been assessed in accordance with TAN15 Planning Guidance.

2.1.3 The Flood Consequence Assessment covers:

• Feasibility assessment using Natural Resources Wales (NRW) data. • Identification of policy updates and review of additional pertinent national, regional

and local flood risk policy. • Investigation of historic / known flood events. • Review of flooding from all sources based upon the most up to date data available

primarily from NRW. • Comparison of existing and proposed flood risk. • Desktop assessment of climate change. • Assessment of the development potential of the site. • Clarification of flood risk mitigation measures. • Conclusions and Recommendations

2.1.4 The Assessment has been prepared in accordance with guidance provided by Technical Advice Note 15: Development and Flood Risk (TAN15) (July 2004).

2.2 Description of the site

2.2.1 The site is located west of Llansamlet and the Swansea Enterprise Park, on the east bank of the Tawe River. The exact location of the site can be seen in Figure 2-1. The site is divided into two distinct sub areas:

• 1a located to the north, covers an area of 1,511m2. It is bounded by the Pant Y Blawd Rd to the west.

• 1b located south of 1a and covers an area of 5,135m2. It is bounded by the Pant Y Blawd Rd to the east.

2.2.2 Currently the sub-area 1a is a concrete car-park, while the sub-area 1b is mainly grassland and forms part of a wider area that was recently cleared, re-profiled and re-landscaped as part of the Lower Swansea Valley Flood Risk Management scheme. It is adjacent to the National Cycle Network (NCN) Route 43 cycle and walking route. Both sites are in Council ownership.

Introduction

Figure 2-1: Location map of proposed site

Introduction

2.3 Local geology

2.3.1 Geological data has been downloaded from the British Geological Survey Website1 for both bedrock and superficial geology.

2.3.2 The site lays over the South Wales Upper Coal Measures Formation, widespread throughout the South Wales Coalfield, from the Twyi estuary, west of Pembrey, east to the Rhymney area on the north crop of the coalfield and to Risca on the south crop. The formation is composed of grey coal bearing mudstones/siltstones with seatearths and minor grey, quartz-rich sandstones, coals and ironstones.

2.3.3 Alluvial deposits sit over the bedrock formation and are composed of clay, silt and sand.

2.4 Soil classification

2.4.1 Soil characteristics across the proposed site have been found on the Cranfield University Website, Soilscapes2.

2.4.2 The site is located at the limit between two soil types presenting different characteristics:

• The sub-area identified 1a is underlined by freely draining floodplain soils with a loamy texture (mix of sand, silt and clay sized particles) in the upper 30cm. Freely draining soils absorb rainfall readily and allow it to drain through the underlying layers.

• The sub-area identified 1b is however underlined by slowly permeable seasonally wet acid loamy and clayey soils presenting a loamy and clayey texture. Impeded soil drainage possibly impacts part of site 1b and this should be considered if this site is taken forward for development. This consideration should include that much of site 1B has recently been the subject of re-landscaping, which could further amend drainage.

1 http://www.bgs.ac.uk/products/digitalmaps/dataInfo.html#_625 Viewed the 28th February 2017 2 http://www.landis.org.uk/soilscapes/ Viewed the 28th February

Policy and Guidance

3. Policy and Guidance 3.1 Flood and Water Management Act, 2010

3.1.1 Combined with the Flood Risk Regulations 2009, (which enact the EU Floods Directive in England and Wales) the Act places significantly greater responsibility on Local Authorities to manage and lead on local flooding issues. The Act and The Regulations together raise the requirements and targets Local Authorities need to meet, including:

• Playing an active role leading Flood Risk Management; • Development of Surface Water Management Plans (SWMP); • Implementing requirements of Flood and Water Management legislation; • Preparation of preliminary flood risk assessments and flood risk management plans; • Development and implementation of drainage and flood management strategies; and • Responsibility for first approval, then adopting, management and maintenance of

Sustainable Urban Drainage System (SuDS).

3.1.2 The Flood and Water Management Act also clarifies three key areas that influence development:

1. Sustainable drainage (SuDS) - the Act makes provision for a national standard to be prepared on SuDS, and developers will be required to obtain local authority approval for SuDS in accordance with the standards, likely with conditions. Supporting this, the Act requires local authorities to adopt and maintain SuDS, removing any ongoing responsibility for developers to maintain SuDS if they are designed and constructed robustly.

2. Flood risk management structures - the Act enables the EA and local authorities to designate structures such as flood defences or embankments owned by third parties for protection if they affect flooding or coastal erosion. A developer or landowner will not be able to alter, remove or replace a designated structure or feature without first obtaining consent.

3. Permitted flooding of third party land - The EA and local authorities have the power to carry out work which may cause flooding to third party land where the works are deemed to be in the interest of nature conservation, the preservation of cultural heritage or people’s enjoyment of the environment or of cultural heritage.

3.1.3 On 1st October 2012, the Welsh Government implemented Section 41 of the Flood and Water Management Act 2010 in the operating area of Dwr Cymru Welsh Water. This requires any developer who wishes to make a connection to the public sewer system, that creates any sewers or lateral drains first to enter a Section 104 agreement with the Water and Sewerage Company that will ensure that any sewers or lateral drains created by the connection will be adopted by the Sewerage Undertaker.

3.2 National Flood and Coastal Erosion Risk Management Strategy, November 2011

3.2.1 The Flood and Coastal Erosion Risk Management Strategy (FCERMS), developed under the Flood and Water Management Act 2010, provides the national framework for flood and coastal erosion risk management in Wales and sets out four objectives:

Policy and Guidance

• Reducing the consequences for individuals, communities, businesses and the environment from flooding and coastal erosion.

• Raising awareness of and engaging people in the response to flood and coastal erosion risk.

• Providing an efficient and sustained response to flood and coastal erosion events. • Prioritising investment in the most at risk communities.

3.2.2 A set of measures has been developed through the Strategy to address the above objectives.

3.2.3 The Strategy identifies the Risk Management Authorities (RMAs) in Wales and the flood and coastal erosion risk management functions they may exercise:

• Natural Resources Wales; • 22 Lead Local Authorities; • Three Internal Drainage Boards; • Dwr CymruWelsh Water, Severn Trent Water and Scottish and Southern Water as

water and sewerage companies in Wales; and • Albion water and Dee Valley water plc as water supply only companies in Wales.

3.3 National Planning Policy and Advice on Flood Risk

3.3.1 In determining an approach for the assessment of flood risk and consequences for the proposed development there is a need to review the policy context. Welsh Assembly Government Guidance advises that managing flooding makes an important contribution to achieving sustainable development.

3.3.2 Planning Policy Wales, supported by TAN153, advises caution in respect of new development in areas at high risk of flooding and sets out a precautionary framework to guide planning decisions. The aim of the framework is to:

• Direct new development away from those areas which are at high risk of flooding; and • Only allow development in high risk areas (Zone C) where they can be justified on the

basis of the justification test (justification of development and acceptability of flood consequences) outlined in TAN15.

3.3.3 Flood Risk should be considered at all stages throughout the planning and development process to ensure that new development proposals in flood risk areas are justified and not exposed to unacceptable flood consequences. TAN15 advises that:

• The susceptibility of land to flooding is a material planning consideration; • NRW has the lead role in providing advice to the planning authority on flood risk

issues; • Development Plans should include site specific policies and proposals for

development and flood risk. Planning authorities should apply the Precautionary Framework when allocating sites for development, seeking to direct new development away from those areas at high flood risk, unless they can be justified on sustainability grounds;

3 http://gov.wales/docs/desh/publications/040701tan15en.pdf Viewed 27th February 2017

Policy and Guidance

• The vulnerability of a proposed land use should be considered when assessing flood consequences; and

• Developers are responsible for providing information to demonstrate that their proposal satisfies the tests contained in TAN15. Furthermore, developers should bear the costs of mitigation, construction and long term maintenance of flood defence required for the proposed development.

3.3.4 Within TAN15 the operation of the precautionary framework is governed by:

• A development advice map which designates land into flood risk zones and which is used to trigger the appropriate planning tests; and

• Definitions of vulnerable development and advice on permissible uses in relation to the location of the development and the consequences of flooding.

3.3.5 As the proposed development is for a site for travellers, TAN15 acknowledges the high vulnerability to flooding. As such it specifies guidance in relation to the approval of such sites for development:

• Caravan and camping site developments are permitted in Zone A where there is minimal flooding, and Zone B where there has been historic flooding but none in recent years; and

• Developments of this nature should be refused in Zone C2 (high flood risk areas with no defence infrastructure), and only advised in Zone C1 (high flood risk areas with defence infrastructure) following the application of the justification tests.

3.3.6 Upon the approval of such developments, TAN15 recommends the erection of suitable warning notices to those occupying the site, and that effective warning and evacuation procedures are in place, in addition to enforcement action if the warning notices/signs become out of date.

3.4 Swansea Local Development Plan, July 2016

3.4.1 There is an ongoing procedure from CCS for replacing the Unitary Development Plan (UDP) by a Local Development Plan (LDP). A Deposit Plan4 has been produced for the period 2010-2025, in accordance with National Planning Policy and Guidance. The Deposit version is, at the time of writing, being subject to an independent Examination in Public process.

3.4.2 The Plan aims to provide a clear planning framework to respond to population growth. Its policies and proposals will address social, economic, environmental and cultural well-being goals and ensure a sustainable development.

4 http://www.swansea.gov.uk/media/17120/Deposit-LDP---consultation-

document/pdf/Deposit_LDP_Consultation_-__FINAL_JULY_2016.pdf Viewed 27th February 2017

Policy and Guidance

3.4.3 There is a current unmet need for 7 new pitches to accommodate Gypsies and Irish Travellers identified in the Council’s draft Gypsy and Traveller Accommodation Assessment (2015, GTAA). An estimate has also been made for newly arising Gypsy and Traveller households. This newly arising need yields a total further requirement for 6 pitches up to 2021 and a further 6 in 2021-25. The Welsh Government GTAA Guidance allows tenancy churn on existing sites to be factored into the supply. The GTAA identifies that 6 pitches would become available at the existing Ty Gwyn site over the Plan period based on past trends which could accommodate newly arising need. The allocated land in the Plan therefore makes provision for at least 7 new pitches for Gypsies and Irish Traveller families identified in the GTAA.

3.4.4 The existing Ty Gwyn site and the allocated LDP site (see Policy H 6) are located within Flood Zone C1, part of the flood plain which is developed and served by significant infrastructure, including flood defences. The Plan sets out that the allocated site satisfies the TAN 15 justification test. Welsh Government (WG) and Natural Resources Wales comments on the Deposit Plan have highlighted that a FCA needs to be undertaken to demonstrate the potential consequences of a flood event are acceptable in line with the requirements of TAN 15. WG also sought clarification on the number of pitches that could be provided.

3.5 Caravan Sites and the Control of Development Act, 1960

3.5.1 As the proposed development is for a traveller site, the development falls under the jurisdiction of the Caravan Sites and Control of Development Act, 19605. Under the Act, CCS has the responsibility to provide sites where caravans maybe brought, whether for holidays or other temporary purposes or use as permanent residences, and to manage the sites or lease them to some other person.

3.5.2 In addition, the local authority (CCS) has the power to:

a. Acquire land which is in use as a caravan site, or which has been laid out as a caravan site;

b. Provide for the use of those occupying the site any services or facilities for their health or convenience; and

c. Provide, sites for the accommodation, working space and facilities for gypsies.

5 http://www.legislation.gov.uk/ukpga/Eliz2/8-9/62 Viewed 28th February 2017

Policy and Guidance

3.6 Relevant Gypsy and Traveller Planning Guidance

3.6.1 At the time of this FCA, Welsh Government had consulted on a new draft Circular: Planning for Gypsy, Traveller and Show People Sites, to provide updated guidance on the planning aspects of identifying sustainable sites for Gypsies and Travellers. On adoption it is proposed that this will replace advice contained in Circular 30/2007 “Planning for gypsy and traveller caravan sites”, Circular 78/91 “Travelling Showpeople” and Circular 76/94 “Gypsy Sites Policy and Unauthorised Camping”. The draft Circular sets out that issues of site sustainability are important for the health and well being of Gypsy and Travellers and consideration may include not locating sites in zone C2 risk of flooding and only considering sites for location within zone C1 risk of flooding in line with guidance contained in TAN 15, given the particular vulnerability of caravans.

3.7 Swansea Local Flood Risk Management Strategy, February 2013

3.7.1 Under the Flood and Water Management Act 2010, CCS, as the Lead Local Flood Authority (LLFA), is responsible for developing a Local Flood Risk Management Strategy (LFRMS)6. The purpose of the LFRMS is to address potential flood risk arising from local sources within the boundaries of the Authority area and to ensure that communities are aware of the risks that exist, and the responsibilities of the Council and other key Risk Management Authorities (RMAs) in terms of flood risk and how local communities can be involved in the strategy.

3.7.2 CCS is the responsible body for managing flood risk from local sources, including surface runoff, groundwater and ordinary watercourses but also wherever there is an interaction between these sources and main rivers or the sea. As one of the Coastal Erosion RMA, it is also responsible for managing coastal flooding and erosion risk.

3.7.3 The RMAs identified as working alongside CCS are:

• NRW are, responsible for managing flood risk from main rivers, reservoirs and the sea. As one of the Coastal Erosion RMA, it has operational responsibilities in flood and coastal erosion risk management;

• Dwr Cymru/Welsh Water, as a water and sewerage company, responsible for floods from water and sewerage systems, burst pipes/water mains or system failures;

• Network Rail, as riparian landowners of culverts crossing and serving the railway network, sharing information related to flood risk from these assets;

• The Rivers and Canal Trust, responsible for the canal network and the protection of its structure (some being referenced as flood defences);

• The South Wales Trunk Road Agents, managing, maintaining and improving the strategic road network (motorways); and

• CCS as the Highways Authority and therefore responsible for managing flood risk on roads and highways.

3.7.4 The strategy sets out primary objectives to reduce flood risk to residents and businesses:

6 http://www.swansea.gov.uk/media/6783/Local-Flood-Risk-Management-

Strategy/pdf/Local_Flood_Risk_Management_Strategy_English1.pdf Viewed 27th February 2017

Policy and Guidance

• To commit to the understanding of Flood and Coastal risks and to ensure that all stakeholders understand their roles and responsibilities in relation to Flood and Coastal risk management;

• To work together with other flood risk management Authorities to reduce flood risk, using all available resources and funds in an integrated way and in so doing derive overall benefit;

• To develop policies for effective land use and management and enhance development control procedures. In order to prevent an increase in flood risk as a result of development, avoiding development in flood risk areas and preventing additional flow entering existing drainage systems and watercourses;

• To establish regular maintenance schedules for flood and coastal erosion risk management assets;

• To raise awareness of and engage people in response to flood and coastal erosion risk;

• To enhance property and community level of resilience; • To take a sustainable and holistic approach to flood and coastal management,

seeking to deliver wider environmental and social benefits; and • To prioritise investment in the most at risk communities.

3.8 Western Wales River Basin District Flood Risk Management Plan, December 2015

3.8.1 The Flood Risk Management Plan (FRMP)7 2015-2021 is produced by NRW every six years to describe the sources and risks of flooding within the river basin district and catchment. The FRMP also includes information on how the RMAs plan to work together with communities and businesses to manage and reduce flood risk.

3.8.2 The Western Wales River Basin District FRMP identifies all sources of flood risk present in the Western Wales River Basin District (Fluvial flooding - Tidal/Coastal flooding – Reservoirs - Surface Water) but focuses on flooding from main rivers, reservoirs and the sea.

3.8.3 NRW divided the Western Wales River Basin District into nine Management Catchments to plan work at a catchment scale. The studied site is located within the Tawe to Cadoxton sub-area, described as rich and varied with both mountainous regions and lowland areas. The River Tawe catchment is predominantly agricultural in the upper and middle reaches with towns built around historic mining areas, adjacent to the main river. The second largest city in Wales, Swansea, developed at the downstream extent of the catchment on heavy industry.

7https://www.naturalresources.wales/media/1076/managing-the-risk-of-flooding-in-the-western-wales-river-basin-

district.pdf Viewed 27th February 2017

Policy and Guidance

3.8.4 Historical flooding affecting the catchment occurred in December 1979, October 1998, October 2000, December 2012 and January 2014. The Tawe experienced significant flooding in 1979 and estimates suggest the event was between a 1 in 75 to 1 in 100-year flood event. The 2014 event was a significant coastal flood event resulting in flood defences being overtopped in Swansea Bay. The FRMP8 states the Llansamlet Community Area as the area at the highest risk in the Tawe Valley with the Swansea Enterprise Zone densely populated. Flood risk is from fluvial flooding from the River Tawe and the Nant Fendrod. Another key community at risk of flooding from main river and sea flooding is also noted as Swansea Community. Measures to reduce flood risk within both areas are:

• To improve existing flood warning service; • To undertake initial assessment and feasibility work for reducing flood risk; and • To build a hydraulic model.

3.8.5 In addition to this FRMP, CCS also produced another FRMP with regards to local flood risk within the area identified as an Indicative Flood Risk Area through the Preliminary Flood Risk Assessment.

3.9 Ogmore to Tawe Catchment Flood Management Plan, 2010

3.9.1 Catchment Flood Management Plans (CFMPs) establish long term policies in order to manage flood risk in a sustainable way with their designated areas. They are used to inform planning and decision making by the different key stakeholders.

3.9.2 The CPMP9 identifies the following sources of flooding within the designated area:

• River Flooding; • Tidally influenced river Flooding; • Surface Water Flooding; • Sewer Flooding; and • Groundwater Flooding.

3.9.3 This Ogmore to Tawe CFMP is divided into 12 sub-areas, which have similar physical characteristics, sources of flooding and level of risk. The most appropriate approaches to manage flood risk for each of the sub-areas has been considered and one of six generic flood risk management policies has been allocated. The site is located within the Lower Tawe sub-area which has been assigned Policy Option 5¹. This policy is applied to areas of moderate to high flood risk where further action can generally be taken to reduce flood risk.

3.9.4 The plan identifies a complementary set of management actions within the designated sub-area:

• To emphasize actions to manage the consequences of flooding; • To increase community and individual awareness of flood risks and encourage people

to take actions to help themselves;

8 https://www.naturalresources.wales/media/1076/managing-the-risk-of-flooding-in-the-western-wales-river-basin-

district.pdf Viewed 27th February 2017 9https://www.npt.gov.uk/ldpexamination/SWW04%20Ogmore%20to%20Tawe%20CFMP%20(EA%20Wales%202

010).pdf Viewed 28th February 2017

Policy and Guidance

• To encourage and support partners in the development of local long term plans to manage all sources of flooding; and

• To encourage and support partners in studies aiming to identify flooding issues from surface water and sewers.

3.10 City and County of Swansea Flood Risk Management Plan, 2015

3.10.1 Under the Flood Risk Regulations 2009, CCS is required to prepare a FRMP10 for local sources of flooding. The Plan sets out objectives and a series of measures to address and reduce flood risk during the 6 -year period before the plan is reviewed.

3.10.2 The FRMP covers flooding from surface water, groundwater, ordinary watercourse and the interface with main river flooding

3.10.3 It takes forward the objectives set out in the LFRMS as well as the ones defined in the Welsh Government’s National FCERM.

3.10.4 CCS has been divided into 36 Community areas within the FRMP. The Community Area of Llansamlet is prone to low through to an isolated high risk from surface water flooding. The plan also states the main cause of flood risk within the area as being from ordinary watercourses and the intakes to existing surface water culverts. In addition to wide measures set out in the FRMS, the following measures are defined specifically to the given area:

• Flood Asset Inspection at 3 locations (Birchgrove Road intakes; Gwernllwynchwyth Road and Winch Wen industrial estate); and

• Investigation of accumulations of Surface Water at 5 locations (Parc yr Helig; Peniel Green Road; Trallwn Playing fields; Frederick Place and Heol Dulais).

3.10.5 River Bran and Fendrod which transverse through the centre of the community are susceptible to high flood risk.

3.11 Multi Agency Protocol for flooding incidents at Lower Swansea Valley. SWLRF Community Level Multi-Agency Response Plan (March 2014)

3.11.1 The protocol aims to provide a framework of procedures that will alleviate residents, members of the public and businesses in the flood risk area, as far as it is practical, from the effects of a 0.1%AEP flood event caused by the overtopping of the Rivers Tawe, Nant-y-Fendrod or Nant Bran. It sets out evacuation procedures which are split into three categories and clarifies the roles and responsibilities of the responding agencies through the provision of a framework that can be expanded upon by the responding organisations to depict their own operational responses within their organisation. The rationale behind this response is that it is not rigid and must be adapted as conditions and circumstances determine at the time.

3.11.2 The protocol is intended to be utilised as a co-ordinating document at the local level, in conjunction with:

10 http://www.swansea.gov.uk/media/14992/Flood-Risk-Management-Plan-

2015/pdf/Flood_Risk_Management_Plan_2015_English_Version.pdf Viewed 27th February 2017

Policy and Guidance

• The emergency response plans of all the responding agencies involved. • The Communications Strategy for the Lower Swansea Valley Flood Risk

Management Project. • City & County of Swansea Flood Plan, City & County of Swansea Major Emergency

Plan and South Wales Local Resilience Forum Flood Arrangement.

3.11.3 The activation of the protocol is underpinned by NRW’s flood warning structure. The area considered to be ‘at risk’ is, therefore, divided into sub areas that distinguish between the flood risk associated with the Nant-y-Fendrod and Nant Bran watercourses and the River Tawe, and each will receive the four-stage flood warning service.

3.12 Strategic Flood Consequences Assessment (Stage 1: 2010) 3.12.1 The Council has previously commissioned an overarching Strategic FCA for the County to

inform the allocation of land in the LDP. The Stage 1 desk based study utilises information from a number of stakeholders to understand potential flood risk across the study area. It identifies areas at potential high risk and provides details of historical records of flooding, flood risk structures and procedures in place in the area.

3.12.2 This aims to present sufficient evidence to apply the justification test of TAN15 to proposed development sites.

3.12.3 Initial assessment of flood sources within the City and Council of Swansea indicates flood risk to be mainly fluvial or tidal. Flood risk from groundwater is considered minimal.

3.12.4 The most significant areas of Flood Zones 2 and 3 are associated with large watercourses namely the Tawe River; this includes Morriston, Llansamlet, and central Swansea.

3.12.5 The report also states that significant areas potentially susceptible to surface water flooding are present in the Tawe corridor such as Morriston and Llansamlet.

3.12.6 It should be noted that this report has been written prior to implementation of the current flood defences on the River Tawe. In general terms, fluvial defences and structures are present in and around the City of Swansea and the towns of Clydach, Glais and Pontarddulais. At the time of the report, fluvial defences within the study area typically consisted of formal raised man-made flood defences, in the form of a number of short reaches of walls or raised banks.

3.12.7 The implementation of SuDS within the study area should be consider as the preferred option to manage flood risk from surface water and drainage.

3.13 Strategic Flood Consequences Assessment (Stage 2: 2012)

3.13.1 Stage 2 of the Strategic Flood Consequences Assessment continues the application of the justification test to ensure that proposed development is steered towards the lowest possible flood risk zone.

3.13.2 Candidate Sites in the Swansea Vale area are predominantly located within DAM Zone C and Flood Zone 2/3. Possible development should be sequentially located to areas of low flood risk first.

Policy and Guidance

3.13.3 The report advises that where Candidate Sites in these higher risk flood zones are progressed, the scope of a site-specific FCA or Stage SFCA should consider the effect of climate change on peak river flows and the future design standard of existing/proposed flood defences. A 1D-2D Estry Tuflow fluvial model has been developed in 2015 for the River Tawe for NRW which includes a wide range of return periods for both defended and undefended scenarios. Thus, the use of this model should be considered for future work and liaison with NRW should be undertaken.

3.13.4 All proposed development should consider the incorporation of SuDS at an early stage to ensure flood risk to third parties is not increased. An allowance for climate change should also be included when sizing SuDS schemes for storm water management.

3.14 The SuDS Manual (C753), CIRIA (2015)

3.14.1 This guidance provides best practice on planning, design, construction, operation and maintenance of Sustainable Drainage Systems (SuDS) to facilitate their effective implementation within both new and existing developments.

3.14.2 The guidance supersedes the original SuDS Manual of 2007. It updates the extensive technical information and includes new guidance on SuDS components and the delivery of SuDS in a variety of situations. The publication is the result of CIRIA Research project (RP)992.

3.14.3 The information presented is a compendium of good practise, based on existing guidance and research both in the UK and internationally, and the practical experience of the authors. As well as providing a framework for designing SuDS with confidence to maximise benefits, it highlights that through engagement and collaboration, SuDS can be integrated into the design of urban areas to create high quality places for future generations. It provides guidance on:

• Maximising amenity and biodiversity benefits • Delivering the key objectives of managing flood risk and water quality • Advice on materials, landscape design and maintenance • Community engagement, costs and benefits.

3.15 Welsh Government SuDS Guidance, December 2016

3.15.1 In December 2016, the Welsh Government published a series of standards for the design of SuDS in proposed developments11. They had defined a series of principles to underlie the design of SuDS, these are defined below:

• To manage water on or close to the surface and as close to the source of runoff as possible;

• Treat rainfall as a valuable natural resource; • Ensure that pollution is prevented at source, rather than relying on the drainage

system to treat or intercept it; • Manage rainfall to help protect people from increased flood risk, and the environment

from morphological and associated ecological damage resulting from changes in flow rates, patterns and sediment movement caused by development;

11 http://gov.wales/docs/desh/publications/151230-suds-standards-en.pdf. Viewed 4th January 2017

Policy and Guidance

• Take account of likely future pressures on flood risk, the environment and water resources such as climate change and urban creep;

• Use the “SuDs Management Train”, using drainage components in a series across a site to achieve a robust surface water management system (rather than using a single “end of pipe” feature, such as a pond, to serve the whole development);

• Maximise the delivery of benefits for amenity and biodiversity; • Seek to make the best use of available land through multifunctional usage of public

spaces and the public realm; • Perform safely, reliably and effectively over the design life of the development taking

into account the need for reasonable levels of maintenance; • Avoid the need for pumping where possible; and • Be affordable, taking into account both construction and long term maintenance costs

and the additional environmental and social benefits afforded the system.

3.16 Climate change allowances

3.16.1 In June 2009 the UK Climate Impact Programme (UKCIP09) released new guidance with respect to climate change predictions (superseding UKCIP02). The predictions have moved from a deterministic approach (i.e. one range of outcomes) to a probabilistic approach (i.e. a range of possible outcomes based on a range of climate change scenarios).

3.16.2 The UKCIP09 predicts that, by the 2050s, temperatures across Wales could rise by between 2.0 and 2.5°C. Annual average rainfall is expected to remain the same, but there is some difference expected in the seasonal variations of the storm events with winter rainfall expected to be more intense, but short-lived, rainfall events and summer rainfall may decrease with more frequent short term droughts.

3.16.3 The sea level along the Welsh coast is expected to rise and result in more severe coastal erosion and inundation in low lying coastal areas.

3.16.4 The Welsh Government developed a Guidance on Climate Change Allowances for Planning purposes in August 201612. This Guidance sets out how projected increases to peak river flows and sea levels, resulting from climate change, should be incorporated into FCAs accompanying planning applications.

3.16.5 The Guidance recommends to use the central estimate for the 2080s time-horizon to assess the potential impact of climate change as part of the FCA. In the Western Wales river basin district, the corresponding projected peak river flow is expected to raise by 30%. The upper and lower estimates for the total potential change anticipated by the 2080s are respectively + 75% and +15%.

12 http://gov.wales/docs/desh/publications/160831guidance-for-flood-consequence-assessments-climate-change-

allowances-en.pdf. Viewed 12th may 2017

Sources of Flood Risk

4. Sources of Flood Risk 4.1 Historical Flooding

4.1.1 This part of the river frontage was a low spot in the flood defences prior to the Lower Swansea Valley Scheme. While the adjacent existing Gypsy and Traveller site is known to have flooded in the 1990s, only one flooding event (in the entire historical record) has been recorded within the extents of the site being analysed in this report. It occurred in December 1979 as a consequence of fluvial flooding from the River Tawe, exceeding its channel capacity. Both sub-areas were impacted although not on their eastern side. Another fluvial flood event occurring in October 1967, is recorded in the vicinity of the site, however there are no records of inundation of the site itself. It should be noted that both events occurred before flood defences were in place. The 1967 event could not be attributed with a return period and estimates suggest the 1979 event was between a 1 in 75 to 1 in 100-year return period. Extents of these events are shown on Figure 4-1. It should be noted that all of these events occurred prior to the implementation of the River Tawe flood defence scheme.

4.1.2 No flooding from tidal sources has been recorded within the sites or their vicinity.

4.2 Flood Risk from Rivers and Sea

4.2.1 The risk of flooding from rivers and the sea has been assessed through the NRW flood maps.

4.2.2 The site is adjacent to the River Tawe and lays entirely within Zone C1. This represents the area with a 1% or greater probability of fluvial flooding or a 0.5% or greater probability of flooding from the sea, each year. Extents of flood zones are shown in Figure 4-2.

4.2.3 The NRW flood risk maps indicate that the source of flooding within the area including the study sites are purely fluvial, despite the proximity of Swansea Bay. Therefore, no tidal flood risk is referenced for the site.

4.2.4 In the vicinity of the site, flood defences are present (see Figure 4-3), including the following:

• Bridge Abutment • Embankment • Flood gate • High Ground • Wall

4.2.5 All of the above as a collective are part of the River Tawe flood defence scheme which provides protection to the site for return periods up to and including the 1 in 100 year plus climate change event. This scheme was implemented in 2012/13 and is maintained by NRW to protect a substantial area of north Swansea particularly the industrial/commercial area to the east of the River Tawe.

Sources of Flood Risk

4.2.6 On the river bank in the immediate vicinity of the site, two types of flood defences are present. The sub-area 1a is protected by a concrete flood defence wall on its western side while an embankment is present west of the sub-area 1b, at the southern end of the given wall. Both are fluvial defences constructed as part of the River Tawe scheme in 2012/13 and have a Standard of Protection of 1 in 100 years plus climate change from fluvial flooding. NRW data indicates the current condition as Fair for the embankment and Very Good for the wall. The responsibility of maintenance of the defence would fall to NRW.

4.2.7 The site lays within an area benefiting from flood defences.

4.2.8 The Welsh Government’s Development Advice Maps are used for planning purposes associated with the use of TAN15. According to the latest Development Advice Map, the area of site that is considered for development falls under Zone C1 as part of the floodplain which is developed and served by significant infrastructure including flood defences. As such, the development is subject to the application of the justification test, including the acceptability of consequences.

Sources of Flood Risk

Figure 4-1: Historical flooding extents recorded in the vicinity of the site

Sources of Flood Risk

Figure 4-2: Flood zones map showing flood risk from rivers and the sea

Sources of Flood Risk

Figure 4-3: Flood defences present in the vicinity of the site and the area benefiting from them

4.3 Flood Risk from Groundwater

4.3.1 Groundwater flooding is the responsibility of the LLFA which is CCS in this instance.

4.3.2 There are no groundwater level monitoring points registered by NRW within the proposed site area.

4.3.3 There are no records or reports of groundwater flooding from either NRW or CCS for the proposed site area.

4.3.4 Groundwater flooding is deemed to be unlikely in this location.

4.4 Flooding from Surface Water

4.4.1 Flooding from land can be caused by rainfall being unable to infiltrate into the natural ground surface or entering the drainage system due to blockage, or flows being above the design capacity. The result of this is temporary localised ponding and flooding.

4.4.2 High intensity storms often with a short duration are sometimes unable to percolate into the ground or be drained by formalised drainage systems. This is due to the capacity of the collection system being insufficient to convey runoff to the underground drainage network.

4.4.3 Flooding can also arise from the sewage network, becoming overwhelmed or blocked and this leads to localised flooding.

4.4.4 The proposed site is currently undeveloped and divided into two sub-areas. Currently the sub-area 1a is a concrete car-park lying on freely draining soils while the sub-area 1b is mainly grassland area lying on slowly permeable soils.

4.4.5 Impeded soil drainage within part of the site is considered to have a negative impact on flood risk from surface water, particularly during intense and/or prolonged rainfall periods.

4.4.6 Data from NRW is consistent with the previous statement with a low to high flood risk from surface water in a minor part west of the sub-area 1b, along the track (Appendix A). No flood risk from surface water is considered for sub-area 1a. Low to high flood risk is present on the Pant Y Blawd Road.

4.5 Flooding from Artificial Sources

4.5.1 Artificial sources of flooding include reservoirs, canals, lakes and mining abstraction.

4.5.2 A single reservoir has been highlighted in the vicinity of the site, on the Nant Y Fendrod tributary.

4.5.3 Based on NRW data (Appendix A), there is a flood risk from a breach of this reservoir. In such events, floodwaters would be conveyed to the confluence with the River Tawe, causing waters from the main river to back up. However, this will not impact the proposed site and a breach of this reservoir is highly unlikely.

4.5.4 Considering the information above, the flood risk from artificial sources is considered negligible.

4.6 Flood Warning and Alerts

4.6.1 NRW provide a flood alert and flood warning service that give properties that are at risk from flooding, advanced notice of when fluvial and coastal flooding is likely to happen. These notices come in the form of a free messaging service, which can be in the form of telephone, SMS message, email, and fax or via the NRW Twitter feed. There are three levels that are provided:

i. Flood Alert- Issued between two hours and two days in advance of flooding and warns that flooding is possible and the customer should be prepared. It advises that the customer should be prepared to act on their flood plan, prepare a flood kit of essential items and monitor local water levels and the flood forecast.

ii. Flood Warning- Issued between half an hour and one day in advance of flooding and warns that flooding is expected and immediate action is required. It advises the customer to move family, pets and valuables to a safe place, turn off gas and electricity and water supplies if it is safe to do so and put flood protection equipment in place.

iii. Severe Flood Warning- Issued as soon as flooding poses a significant threat to life and warns that a flood is expected to be severe and there is a danger to life. It advises that the customer should stay in a safe place with a means of escape, be ready to leave home and to co-operate with the emergency services.

4.6.2 The site is eligible to receive Flood Alerts and Flood Warnings from NRW (see Figure 4-4). The Flood Warning area code is 102FWF123B, monitoring the River Tawe at Tawe Vale and Swansea City centre. According to NRW records, the earliest recorded flood warning/alert/watch was on the 15/02/2006 and no data precedes this; so it is assumed that the start of the recorded period was around this date. These Flood Alerts, Flood Warnings, and Severe Flood Warnings are triggered by water levels exceeding 5.7m, 6.2m, and 6.7m at the Morfa, Tawe gauge (059003) respectively and water levels exceeding 3.4m, 4.95m, and 5.2m at the Ynystanglws, Tawe gauge (059001) respectively. It should be noted that whilst the levels above are specified as the trigger levels the water level has exceeded this in the past, but no alert has been issued which would imply that the levels specified are conservative and could cause false warnings.

4.6.3 The parent Flood Alert area: is designated under the code 102WAFF22, monitoring the Lower Tawe area in the Tawe catchment south of the M4 motorway. It includes both the River Tawe and its tributary, the Nant Y Fendrod. Within the area, two flood alerts on the 26/01/2016 and the 03/09/2016 have been issued over the period since the first flood alert on 15/02/2006.

4.7 Residual Flood Risk

4.7.1 Although the site is protected by defences with a high level of protection, residual flood risk needs to be considered. Failure through overtopping of the defences in an extreme event (in excess of the 1 in 100 year event plus climate change) or breaching (although NRW are required to maintain the River Tawe flood defence) could still occur and therefore, a residual risk remains. Such an event would result in flooding behind the defence across a large part of Swansea which includes almost the entire area between Llansamlet and the River Tawe.

Sources of Flood Risk

Figure 4-4: Flood warning and flood alerts areas recorded in the vicinity of the site

Development Planning Considerations

5. Development Planning Considerations 5.1 General Development Considerations

5.1.1 The area of the site for the proposed development falls within Zone C1 based on TAN15 as part of the floodplain which is developed and served by significant infrastructure including flood defences. Under the TAN15 guidance, the development is subject to the application of the justification tests, including the acceptability of consequences.

5.2 Justifying Location of Development

5.2.1 TAN15 Guidance states that “highly vulnerable development in Zone C2 is not permitted and that all other new development should only be permitted within Zones C1 and C2 if determined by the planning authority to be justified in that location.” Development is only justified if demonstrating:

i. Its location in Zone C is necessary to assist, or be part of, a local authority regeneration initiative or a local authority strategy required to sustain an existing settlement; or

ii. Its location in Zone C is necessary to contribute to key employment objectives supported by the local authority, and other key partners, to sustain an existing settlement or region;

and

iii. It concurs with the aims of Planning Policy Wales (PPW) and meets the definition of previously developed land; and

iv. The potential consequences of a flooding event for the particular type of development has been considered, and in terms of the criteria contained in sections 5 and 7 and appendix 1 of the TAN15, found to be acceptable.

5.2.2 The proposed development is considered as a highly vulnerable development, based on TAN15 criteria.

5.2.3 The proposed allocation is justified in-line with the above TAN 15 tests since it is necessary to assist with the delivery of land to satisfy unmet accommodation needs for Gypsies and Travellers and is proposed as part of the Council's LDP (meeting test i); and it is previously developed land which has been landscaped (meeting test iii). Forthcoming sections of this FCA assess the potential consequences of a flooding event and the allocation's acceptability in terms of test iv.

Development Planning Considerations

5.3 Proposed Design Plan

5.3.1 According to the “Designing Gypsy and Traveller Sites” Guidance13 for the Welsh Government, each pitch within the proposed development site should be capable of accommodating an amenity block, a mobile home/touring caravan and parking for two vehicles, respecting the following dimensions:

• Mobile Home should measure up to 20 metres long and 6.8 metres wide, according to Section 60 of the Mobile Home (Wales) Act;

• Parking spaces must be a minimum of 2.4 by 4.8 metres each; • Amenity Block should occupy a minimum of 23m2 area.

5.3.2 A 3-metre gap must be respected between a mobile home and any pitch/site boundary

5.3.3 A 6-metre gap must be respected between mobile homes for fire safety and privacy reasons.

5.3.4 Considering the above elements, 7 pitches can be contained within sub-area 1b (as outlined in Figure 5-1) with further capacity for pitches within 1a. The exact layout will be subject to further testing and consultation with the Gypsies and Travellers, but the plan illustrates that 7 pitches can be accommodated on 1b.

13 https://www.valeofglamorgan.gov.uk/Documents/Living/Planning/Policy/LDP/Examination-Documents-

2015/Designing-gypsy-and-traveller-sites-May2015.pdf Viewed 28th March 2017

De

Figure 5-1: Proposed design for pitches within sub-area 1b

Development Planning Considerations

5.4 Fluvial Flood Risk Considerations

5.4.1 According to the TAN 15 Guidance, flood risk should be assessed under a range of extreme events from the threshold to a flood having a probability of occurrence of 0.1%. When dealing with existing flood defences, particular attention should be given to the scenarios causing overtopping of the defences.

5.4.2 The Tawe Vale Scheme Model is an ESTRY-TUFLOW model that was developed in 2015 for NRW. This model incorporated the flood defence scheme in the Lower Tawe Valley. This model, being the most up to date covering the study area, has been utilised in this study to assess flood consequences at the proposed site and the flood mechanisms.

5.4.3 Flood events with 1% and 0.1% chance of occurring each year have previously been run; including a 1% annual chance + climate change events (20% increase in peak flow). The latter climate change event was run with the old climate change guidance; so climate change events were run based on the updated climate change guidance for the Western Wales river basin. These climate change events were run with the central estimates for the 2050 epoch with a 25% increase in peak flows and the 2080 epoch with a 30% increase in peak flows. The model considers flood defences in place in the surrounding area. It should be noted that there is a degree of uncertainty in estimating climate change events.

5.4.4 The proposed development will increase the area of impermeable surface compared to the current state of the site, particularly across the 1b sub-area. The increase in impermeable area will be small and can be managed at detailed design stage through the implementation of a drainage strategy for the site. This will ensure that surface water runoff from the site will be managed to Greenfield Runoff Rates.

5.4.5 The site topography is intended to be retained and the only permanent features on the site will be the amenity blocks. The overall impact upon floodplain storage will be minimal and minor re-landscaping of the site can be implemented to negate any loss of floodplain storage.

5.4.6 Figure 5-5 and Figure 5-4 show flood depths across the area for the 1% and 0.1% AEP flood scenarios. No flooding occurs within the extents of the proposed site for the 1% and 1%+ 25% CC scenario. The site is however shown to partially flood during the 1% plus CC scenario and the 0.1% flood event. In sub area 1a, flood depths vary between 0 and 2.44 meters in the 0.1% AEP event while in sub-area 1b, flood depths are between 0 and 2.37 meters on the eastern side.

5.4.7 As highlighted by the model outputs, the River Tawe flood defence provides a significant level of protection up to and including the 1% plus 25% climate change event with defence levels being ~11.61m in height in the model in the vicinity of the site. Flooding, however, still occurs in the 0.1% flood event because of defence overtopping.

5.4.8 Figure 5-6 shows these results.

Development Planning Considerations

5.4.9 The Lower Swansea Vale model results show that the defences overtop between 7.25 and 7.5 hours in the 0.1% AEP event. The site starts to flood at 7.25 hours and fully flood by 8.25 hours. The travel time from the upstream section of the catchment to the site of interest is ~2.5 hours. The time from the point at which the flood alert is issued to the time at which the site is inundated is ~3 hours. Therefore the total time available to evacuate the site is ~5.5 hours. This time is the travel time plus the time from the issue of the flood alert to defence overtopping. This time is sufficient for the site to be evacuated. This is because the distance from the potential traveller site to a point of safety in the vicinity of the A4067 is 600m which can be travelled in ~5 minutes. In addition it is understood that it would take no longer than 1 hour to pack up a caravan and hitch up to a vehicle. A clear evacuation route has been specified in Figure 5-3.

5.4.10 Furthermore, residents will have an awareness of the emergency evacuation routes and how to evacuate the site in a timely and safe manner. The site will be evacuated once a flood warning has been issued.

Figure 5-2. Possible signage.

Development Planning Considerations

Figure 5-3. The proposed evacuation route

Development Planning Considerations

Figure 5-4: Maximum Depths provided by the model for a 0.1% flood event

Development Planning Considerations

Figure 5-5: Maximum Depths provided by the model for a 1% flood event

Development Planning Considerations

Figure 5-6. Maximum depths provided by the model for the 1% AEP with 25% climate change allowance event.

Development Planning Considerations

Figure 5-7: Flood propagation in the 0.1% AEP event at sites 1a and 1b from 7.25 hours to 8.50 hours.

7.25 hours 7.50 hours 7.75 hours

8.00 hours 8.25 hours 8.50 hours

Development Planning Considerations

5.4.11 Both sites are located in areas that receive Flood Warnings, so a well-managed and effective system of Flood Warnings and efficient evacuation in line with a Flood Evacuation Plan is deemed sufficient. The time to peak is ~12 hours based on the mean time to peak from four isolated hydrographs from the Ynystanglws gauge upstream. Therefore, there would be sufficient time for flood warnings to be activated and the sites to be evacuated.

5.4.12 The site evacuation route is shown in Figure 5-3. The total length of the route is approximately 600m to the A48 and during the modelled 0.1% AEP flood event it did not flood. For a car towing a caravan the total time to drive this route is estimated to be 5 minutes. It is reasonably estimated that the residents of the site would take no more than one hour to pack up their caravan and be ready to evacuate the site. This would be required upon receipt of a flood warning which was confident that a flood event would be experienced which exceeded the 1% AEP plus climate change event.

5.4.13 Furthermore, the model results for the 1000 year defended scenario from the Lower Swansea Vale model reveal that the site floods when flows overtop the defences upstream of the site. The overtopping of this defence occurs between 7.25 and 7.5 hours and the flow then propagates towards the site from the north. Site 1b subsequently starts to flood at 7.25 hours. Site 1a starts to flood at 7.75 hours given that the total evacuation time for the site is estimated to be 1 hour, there is a significant difference between the evacuation time and the time it takes for the River Tawe flood defences to overtop locally. Figure 5-7 shows this flood propagation.

5.4.14 Users of each site should be made aware of the available access and egress route in the event of an emergency. Several signs should be placed across the site, along approaches to the site, and should be placed in an area with a good level of visibility. Figure 5-2 shows possible signage that could be used.

5.5 Surface Water Flood Risk Considerations

5.5.1 TAN15 states that development should not increase the risk of flooding elsewhere through an increase in surface runoff. Runoff from a development can, if not appropriately controlled, result in flooding at other locations and significantly alter the frequency and extent of flooding downstream in the catchment.

5.5.2 TAN15 also advises that the aim of any new development should not be to create additional runoff when compared to the undeveloped state of the site. The use of SuDS is recommended to help achieve this aim.

5.6 Other Flood Risk Considerations

5.6.1 As discussed previously, the flood risk from artificial sources and groundwater have been deemed to be negligible. Therefore, no development considerations to mitigate flooding from these sources is required.

Summary and Conclusions

6. Summary and Conclusions 6.1.1 Capita has been commissioned by City and County of Swansea Council to undertake a Flood

Consequence Assessment for a proposed traveller site on Pant Y Blawd Road, Morriston.

6.1.2 The proposed allocation is justified in-line with the TAN 15 tests since it is necessary to assist with the delivery of land to satisfy unmet accommodation needs for Gypsies and Travellers and is proposed as part of the Council's LDP (meeting test i); and it is previously developed land which has been landscaped (meeting test iii).

6.1.3 The site is deemed to be a highly vulnerable land use.

6.1.4 Flood risk at the site has been considered from all sources. Flood risk from tidal sources, groundwater and artificial sources is considered negligible within the area.

6.1.5 The proposed development is located within Zone C1. The site benefits from defences which are currently maintained by NRW to a 1% AEP plus 20% climate change Standard of Protection. The site has been shown through additional modelling to be protected up to the 1% AEP plus 25% climate change Standard of Protection which is the central 2050 epoch allowance. The defences do however have the potential to overtop in the 0.1% AEP event.

6.1.6 Mitigation has been considered and the most appropriate mitigation measure that meets the guidance set out in TAN15 is Flood Warning and Flood Alerts. Residents of the site will be mandatorily signed up to the existing flood warning scheme for the flood alert area (102FWF123B) which covers the entire Swansea area between Llansamlet and the River Tawe.

6.1.7 The Lower Swansea Vale model results show that the defences overtop between 7.25 and 7.5 hours. The site starts to flood at 7.25 hours and fully flood by 8.25 hours. The travel time from the upstream section of the catchment to the site of interest is ~2.5 hours. The time from the point at which the flood alert is issued to the time at which the site is inundated is ~3 hours. Therefore the total time available to evacuate the site is ~5.5 hours. This time is the travel time plus the time from the issue of flood alert to defence overtopping. This time is sufficient for the site to be evacuated. This is because the distance from the potential traveller site to a point of safety in the vicinity of the A4067 is 600m which can be travelled in ~5 minutes. In addition it is understood that it would take no longer than 1 hour to pack up the caravan and hitch up to a vehicle. A clear evacuation route has been specified in Figure 5-3.

6.1.8 There is a flood risk from surface water within part of the site. Increasing the coverage of impermeable surfaces will increase surface water runoff. A comprehensive drainage strategy will be completed to ensure that the site runoff will be managed to Greenfield Runoff Rates. The drainage strategy will be completed once the layout of the site has been confirmed and this will ensure that the site manages surface water runoff and drainage.

6.1.9 This site is preferable to other sites in the vicinity, including the ‘tolerated site’ at Millstream Way because the evacuation route is short and the time to defence overtopping in the 0.1% AEP event is similar and therefore this site is the preferred site for development.

Summary and Conclusions

6.1.10 The development is deemed tolerable in relation to Appendix 1c paragraph A1.15 in the TAN15 guidance, although gypsy/traveller sites are not explicitly identified in the table. The site is protected up until the 1% AEP with 25% climate change allowance because the flood defences provide this Standard of Protection. When the Standard of Protection is exceeded flooding propagates along Pant-y-Blawd Road before causing inundation on the site. The residents will have been mandatorily signed up for flood warnings and therefore will have evacuated the site prior to defence overtopping. Once the residents have evacuated the only remaining infrastructure on site will be the amenity blocks. Flood depths and velocities experienced in the 0.1% AEP event are in excess of those specified in the table, however, the residents will have already evacuated and the depths and velocities will be experienced across the entire industrial area within which the gypsy/traveller site is situated which covers a substantial swathe of the city of Swansea. In addition the table is regarded as indicative guidance.

6.1.11 This FCA concludes that the traveller site is suitable to be developed in line with TAN15 because it satisfies the relevant criteria of the Justification Test. The site is therefore deemed to be appropriate for development as a Gypsy Traveller site on the premise that there is a residual risk to the site from overtopping of defences in the 1 in 1000 year event. This risk is successfully mitigated by the implementation of a comprehensive evacuation plan and mandatory sign up of residents to the NRW Flood Warning service. This will include signage on site to advise on the flood risk and signage to identify the short length of evacuation route to the vicinity of the A48/A4067 junction which is the closest safe location. This signage should be permanent.

Appendices

Appendices

Appendix A

Appendix A

Appendix A