Leckwith Road Site Flooding Consequences Assessment

8 September 2017

Cardiff Council

Mott MacDonald Fitzalan House Fitzalan Road Cardiff CF24 0EL United Kingdom

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Cardiff Council County Hall Atlantic Wharf Leckwith Road Site Cardiff 380206 009 A CF10 4UW http://pims01/pims/llisapi.dll/properties/2119390873 Flooding ConsequencesMott MacDonald Assessment

8 September 2017

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Mott MacDonald | Leckwith Road Site Flooding Consequences Assessment

Issue and Revision Record

Revision Date Originator Checker Approver Description A 8 September 2017 N Haines N M Price C Williams First issue

Document reference: 380206 | 009 | A

Information class: Standard

This document is issued for the party which commissioned it and for specific purposes connected with the above- captioned project only. It should not be relied upon by any other party or used for any other purpose.

We accept no responsibility for the consequences of this document being relied upon by any other party, or being used for any other purpose, or containing any error or omission which is due to an error or omission in data supplied to us by other parties.

This document contains confidential information and proprietary intellectual property. It should not be shown to other parties without consent from us and from the party which commissioned it.

This report has been pr epared sol el y for use by the party which commissi oned it (the ‘Client’) i n connecti on with the capti oned proj ect. It should not be used for any other purpose. N o person other than the Client or any party who has expressl y agreed ter ms of r eliance with us (the ‘Reci pient(s)’) may rel y on the content, i nformati on or any views expressed i n the repor t. We accept no duty of care, responsi bility or liability to any other r eci pient of thi s document. T his r eport is confi denti al and contains pr opri etar y intell ectual property.

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We accept no r esponsibility for any error or omission i n the r eport which is due to an error or omission i n data, infor mation or statements supplied to us by other par ties incl udi ng the client (‘D ata’). We have not i ndependentl y verified such D ata and have assumed it to be accurate, complete, reli abl e and current as of the date of such infor mation.

Forecasts presented i n this document were pr epared usi ng Data and the report is dependent or based on D ata. Inevitabl y, some of the assumptions used to develop the for ecasts will not be realised and unantici pated events and circumstances may occur. C onsequentl y M ott MacDonal d does not guarantee or warr ant the concl usi ons contained in the repor t as there are li kel y to be differ ences between the for ecasts and the actual results and those di ffer ences may be material. Whil e we consi der that the infor mation and opini ons gi ven i n this r eport are sound all parti es must rel y on their o wn skill and judgement when making use of it.

Under no circumstances may this report or any extr act or summar y ther eof be used in connection with any public or pri vate sec urities offering i ncluding any rel ated memorandum or prospectus for any securities offering or stock exchange listing or announcement.

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Mott MacDonald | Leckwith Road Site Flooding Consequences Assessment

Contents

Executive summary 1

1 Introduction 3 1.1 Scope 3 1.2 Site location and description 4 1.3 Proposed development 5

2 Sources of information and consultations 6 2.1 Planning Policy Wales (PPW) 6 2.2 Technical Advice Note 15 Development and Flood Risk (TAN15) 7 2.2.1 Development Advice Zones 7 2.2.2 Development category 7 2.2.3 Justifying the location of development 7 2.2.4 Assessment of flooding consequences 8 2.2.5 Surface water management 9 2.3 Local planning policy and guidance 9 2.3.1 Cardiff Strategic Flood Consequences Assessment (SFCA) 9 2.3.2 Cardiff Local Flood Risk Management Strategy (LFRMS) and Cardiff Flood Risk Management Plan (FRMP) 10 2.4 Consultation with Natural Resources Wales 10 2.4.1 Preliminary pre-application enquiry 10 2.4.2 Product 4 flood data 11 2.4.3 Good Practice Guide 101 – Producing flood risk hydraulic models and flood consequences assessments for development planning purposes 11 2.4.4 Other correspondence with NRW 11 2.5 Consultation with Lead Local Flood Authority (Cardiff Council) 12 2.5.1 Request for local flood information 12

3 Assessment of the suitability of the site for development proposed 13 3.1 Development advice zone 13 3.2 Justifying the location of development in principle 13

4 Assessment of flooding consequences 14 4.1 Historical records of flooding 14 4.1.1 Information from NRW “Product 4” data 14 4.1.2 Information from the Cardiff SCFA 14 4.2 Flooding from rivers 14 4.2.1 Information from NRW “Product 4” data 14 4.2.2 Information from other sources 16

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Mott MacDonald | Leckwith Road Site Flooding Consequences Assessment

4.3 Flooding from the sea 16 4.3.1 Information from NRW “Product 4” data 16 4.3.2 Information from other sources 16 4.4 Surface water flooding 17 4.5 Flooding from sewers 17 4.6 Groundwater flooding 18 4.7 Flooding from reservoirs and canals 18

5 Development constraints and flood mitigation measures 20 5.1 Operational escape and evacuation routes 20 5.2 Flood free during the indicative threshold frequency 21 5.3 Tolerable conditions in extreme floods 21 5.4 Structural integrity and flood resilience 22 5.5 The development does not increase flood risk elsewhere 22 5.6 Residual risks 23

6 Conclusions and recommendations 24 6.1 Suitability of the site for development 24 6.2 Constraints and mitigations 24 6.3 Qualifications and recommendations for further work to determine further flood-related constraints 24

Appendices 26

A. Consultation with Natural Resources Wales 27 A.1 Preliminary Pre-Planning Application Screening 27 A.2 “Product 4” data 28 A.3 Other correspondence 29

B. Consultation with Cardiff Council (LLFA) 30

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Mott MacDonald | Leckwith Road Site 1 Flooding Consequences Assessment

Executive summary

Cardiff Council is investigating options for the redevelopment of land off Leckwith Road, Leckwith, Cardiff CF11 8BR. Cardiff Council is investigating the development of a new ten form of entry school in the site.

Cardiff Council commissioned Mott MacDonald to undertake a preliminary Flooding Consequences Assessment (FCA) to identify the acceptability of flooding consequences in accordance with Planning Policy Wales (TAN15) and local planning guidance. The objectives of the FCA were as follows: ● To determine the viability of the proposed development options with respect to flood risk. ● To identify flooding-related development constraints, and potential mitigation measures likely to be necessary to reduce the predicted flooding consequences to an acceptable level in line with TAN15 guidance, such that the cost and practicability of these mitigations and constraints can be assessed by others and balanced against other factors. The FCA was undertaken in consultation with Natural Resources Wales. Consultation with the Lead Local Flood Authority, Cardiff Council was request however it was not received in time to inform this report. The site lies between two major rivers in Cardiff, the River Ely and the River Taff, and is approximately 4.5km away from the Severn Estuary shoreline at Cardiff Bay Barrage. The site can be affected by both fluvial and tidal events however flood risk in the area is fluvially- dominated. The site is also at low risk of surface water, reservoir and ground water flooding. NRW data shows that the site was not affected by the two major flooding events in Cardiff in December 1960 and December 1979.

The TAN 15 Development Advice Map (DAM) indicates that the site area falls within development advice zone B “Areas know to have been flooded in the past evidenced by sedimentary deposits”, and zone C1 “areas of the floodplain which are developed and served by significant infrastructure, including flood defences”.

Due to the location of the site in zone C1, the LPA should accept the principle of a school or residential development at the site, subject to parts (i) or (ii) and (iii) and (iv) of the TAN 15 Justification Test being passed.

However, the assessment has shown that the available escape and evacuation routes are not operational under “all conditions” (required by part (iv) of the TAN 15 Justification Test). A school or residential development on this site will therefore be subject to acceptance by NRW and the LPA of a departure from this guidance. If it is established that a new school is required then, in selecting a site for development, the risks, and consequences of flooding at this site should be balanced against those at available alternative sites.

If the principle of development at this site is accepted by the LPA then, in order for the development to proceed, it will be necessary to demonstrate via a full flooding consequences assessment that the potential consequences of flooding as a result of the development are otherwise acceptable in terms of the criteria set out in TAN 15.

Based on our assessment it is anticipated that the following flood mitigation and management measures are likely to be required for the development of a school at this site.

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Mott MacDonald | Leckwith Road Site 2 Flooding Consequences Assessment

● To meet this TAN 15 acceptability criteria requirement, it is expected that the area around the main school building including the car park and access road will need to be at least 7.84m AOD. Open Source Lidar data indicates that existing ground levels are at or above this elevation. ● The main school building should have a finished flood level of at least 8.14m AOD. Open Source Lidar data indicates that the majority of the site is elevated above this level. If the school building were to be located in either the western segment of the site or the north- western portion of the eastern segment of the site, it is anticipated that building floor levels would only need to be elevated above existing ground levels to the normal extents required by Building Regulations. If the school building were to be located in the south-eastern portion of the eastern segment of the site, then it is anticipated that the building flood levels would need to be approximately 0.2m above existing ground levels. ● Flood resilience measures should be considered for all school buildings to at least a level of 8.37m AOD. ● If the school building were to be located in south-eastern portion of the eastern segment of the site, compensatory flood storage will need to be provided. If the school building were to be located in either the western segment of the site or the north-western portion of the eastern segment of the site, the need to provide significant compensatory flood storage could be avoided. It is recommended that:

● An assessment of the scale of the requirements for compensatory storage should be progressed as early as possible in the feasibility stage. This assessment may not identify an acceptable technical solution or may demonstrate that it is not practicable to provide the compensatory storage required with respect to cost and programme. For example, the solution could involve moving or removing significant volumes of material, remediation or inflated disposal costs of material due to historical uses (landfill) and may necessitate work on other Cardiff Council or third-party land. ● The assessment of land raising is based upon Open Source Lidar topographic data and should be verified with surveyed topographic data once available. The flood levels provided in this report are estimates and should be treated with caution. ● It is also recommended that the public sewer asset location plan and flood history are obtained for the site to inform this assessment of flood risks and constraints.

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Mott MacDonald | Leckwith Road Site 3 Flooding Consequences Assessment

1 Introduction

Cardiff Council is investigating options for the redevelopment of several schools in Cardiff where the existing school buildings are in poor condition or they will not serve the predicted future need. One such school is the Fitzalan High School. An initial high-level scoping report identified that there are significant constraints in relation to flooding to one of the sites being investigated by the Council, a site off Leckwith Road. Cardiff Council therefore commissioned Mott MacDonald to undertake an assessment of flooding consequences to identify the levels and other mitigations that would be required.

1.1 Scope Cardiff Council is investigating options for the redevelopment of land off Leckwith Road, Leckwith, Cardiff CF11 8BR.

The scope of the FCA reflects the stage of planning consideration and current level of detail available.

The FCA was undertaken in consultation with Natural Resources Wales and the Lead Local Flood Authority, Cardiff Council.

The information and recommendations presented within this assessment are dependent upon the accuracy and reliability of the information, correspondence and data available to Mott MacDonald, at the time of the assessment. Any party developing detailed design should not rely on assumptions made in this report but should satisfy themselves in that regard.

The FCA includes an assessment of the predicted effects of climate change over the lifetime of the development. Our assessment of the effects of climate change is based on the guidance provided by Welsh Government in place at the time of this report. These recommendations may change in the future increasing the extent of predicted effects and we would recommend that you seek further advice should this occur during the lifetime of the project.

Mott MacDonald has followed accepted procedure in providing the services but given the residual risk associated with any prediction and the variability which can be experienced in flood conditions Mott MacDonald takes no liability for, and gives no warranty against, actual flooding of any property (client’s or third party) or the consequences of flooding in relation to the performance of the service. The Flooding Consequences Assessment has been prepared for the purposes of identifying likely development constraints and associated mitigations only.

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Mott MacDonald | Leckwith Road Site 4 Flooding Consequences Assessment

1.2 Site location and description The site, hereafter referred to as “Leckwith Road Site”, is located in the Leckwith Moors, off Leckwith Road, west Cardiff at National Grid Reference (ST 16221 75693) The site lies between two major rivers in Cardiff: the River Ely (approximately 100m to the south-west) and the River Taff (approximately 1.6 km to the east) (Figure 1). The site is located approximately 3.8km away from the Severn Estuary shoreline at Cardiff Bay Barrage.

Figure 1: Location of Leckwith Road Site

Source: Base Mapping: Crown copyright and database 2016, Ordnance Survey

This site is approximately 10.3ha in area. The topography of the site is varied. Open source Lidar indicates that the western segment of the site slopes downward from the A4232 embankment at around 13.5m AOD to around 9m AOD at the boundary with Pwll Coch School. The eastern segment of the site slopes downward from west to east from around 11.5m AOD at the boundary with Pwll Coch School to around 8m AOD at Leckwith Road. The site for the most part comprises artificial or grass playing pitches however the area to the west and south appears to be vegetated with trees and shrubs. The site is bounded to the south by the Leckwith Athletics track, to the south-west by the A4232, to the north by residential development (Lawrenny Avenue) and Pwll Coch School, and to the east by Leckwith Road (Figure 2).

A significant drain dissects the site running from the rear of properties along Lawrenny Avenue, then down to eastern boundary of Pwll Coch School, along the rear of the Leckwith Athletics track stand and through to a small pond area adjacent to the A4232 road.

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Mott MacDonald | Leckwith Road Site 5 Flooding Consequences Assessment

Figure 2: Approximate extent of the development site

Source: Base Mapping: Crown copyright and database 2016, Ordnance Survey. Approximate red line boundary produced by Mott MacDonald 2017.

1.3 Proposed development Cardiff Council is investigating the option of constructing of a new ten form of entry school at the site.

The FCA focuses on the identification of flood-related constraints and associated mitigation or management measures that would be necessary for each of the development proposal to be acceptable in terms of planning policy.

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Mott MacDonald | Leckwith Road Site 6 Flooding Consequences Assessment

2 Sources of information and consultations

Mott MacDonald accessed the following sources of information in the preparation of this FCA:

● Planning Policy Wales (PPW). ● Planning Policy Wales Technical Advice Note 15 (TAN15): Development and Flood Risk. ● Natural Resources Wales’ “Product 4” data, reference ATI-13209a (received 17 July 2017) and ATI-13209e (received 25 July 2017). ● Natural Resources Wales’ online long term flood risk interactive maps (https://naturalresources.wales/evidence-and-data/maps/long-term-flood-risk/?lang=en last accessed August 2017). ● Open source LiDAR data (http://lle.wales.gov.uk/Catalogue/Item/LidarCompositeDataset/?lang=en), accessed in July 2017. ● Cardiff Strategic Flood Consequences Assessment Phase 2 Part 1 Update Extend Development Lifetime to 2110 Areas A, G, H and I (Final Report, November 2011) (https://www.cardiff.gov.uk/ENG/resident/Planning/Local-Development- Plan/EvidenceBaseDocs/SCFA%20Report%20Phase%202%20Part%201%20Update%20Ex tend%20Dev.%20lifetime%20to%202110%20Areas%20AGHandI.pdf last accessed July 2017). ● Cardiff Local Flood Risk Management Strategy (LFRMS) (September 2014) (https://www.cardiff.gov.uk/ENG/Your-Council/Strategies-plans-and-policies/Local-flood-risk- management-strategy/Pages/default.aspx last accessed July 2017). ● Cardiff Flood Risk Management Plan (FRMP) (December 2015) (http://www.cardiff.gov.uk/ENG/resident/Community-safety/Flood-and-Coastal-Erosion-Risk- Management/Documents/Cardiff%20Flood%20Risk%20Management%20Plan.pdf last accessed July 2017). ● Welsh Government Policy Clarification Letter “Climate change allowances for planning purposes”, document reference Cl-03-16 (http://gov.wales/topics/planning/policy/policyclarificationletters/2016/cl-03-16-climate- change-allowances-for-planning-purposes/?lang=en last accessed July 2017). ● The joint EA and DEFRA Technical Report, “Flood Risk Assessment Guidance for New Development” (report number FD2320/TR2), dated October 2005. ● BSI Standards Publication “Assessment and managing flood risk in development – Code of Practice” BS8533:2011.

We also undertook consultation with Natural Resources Wales and Cardiff Council as Lead Local Flood Authority.

2.1 Planning Policy Wales (PPW) Planning Policy Wales (PPW) provides the planning policy framework under which the Local Planning Authorities (LPAs) must prepare their Local Development Plans (LDPs). This should encourage patterns of development that are economically, socially and environmentally sustainable. As part of this, PPW highlights the need to reduce flood risk by avoidance of development within high risk areas, as opposed to the previous approach of flood defence and mitigation of the consequences of flooding.

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Mott MacDonald | Leckwith Road Site 7 Flooding Consequences Assessment

2.2 Technical Advice Note 15 Development and Flood Risk (TAN15) Accompanying PPW, Technical Advice Note 15: Development and Flood Risk (TAN 15) provides technical guidance on the assessment of flooding risk and consequences and includes advice on what should be included in FCAs.

2.2.1 Development Advice Zones Figure 1 of TAN 15 defines three Development Advice Zones (A, B, and C), which are summarised in Table 1. The figure also attributes different planning actions for each of the zones.

Table 1: Development Advice Zones Zone Sub- Description of Zone Use within PPW and TAN 15 Zone A Considered to be at little or no risk Used to indicate that justification test is not of fluvial or tidal/coastal flooding applicable and no need to consider flood risk further B Areas know to have been flooded Used as part of precautionary approach to in the past evidenced by indicate where site levels should be checked sedimentary deposits against the extreme (0.1%) flood level. If site levels are greater than the flood levels used to define adjacent extreme flood outline there is no need to consider flood risk further C Based Environment Agency / NRW Used to indicate that flooding issues should extreme flood outline, equal to or be considered as an integral part of decision greater than 0.1% (river, tidal or making by the application of the justification coastal) test including assessment of consequences C1 Areas of the floodplain which are Used to indicate that development can take developed and served by place subject to application of justification significant infrastructure, including test, including acceptability of consequences flood defences C2 Areas of the flood plain without Used to indicate that only less vulnerable significant flood defence development should be considered subject infrastructure to application of justification test, including acceptability of consequences. Emergency services and highly vulnerable development should not be considered Source: Figure 1, Planning Policy Wales TAN 15

2.2.2 Development category Section 5 of TAN 15 states “particular flooding consequences may not be acceptable for particular types of development … the precautionary framework identifies the vulnerability of different land uses to flooding”.

TAN 15 divides types of development into the following three categories: emergency services, highly vulnerable development, and less vulnerable development.

Table 2 of TAN 15 identifies schools and residential developments as “highly vulnerable development”.

2.2.3 Justifying the location of development The overarching aim of TAN15 is to ensure that new development is “directed away from zone C and towards suitable land in zone A, otherwise to zone B, where river or coastal flooding will be less of an issue”.

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Mott MacDonald | Leckwith Road Site 8 Flooding Consequences Assessment

Furthermore, Section 6 of TAN 15 states that “highly vulnerable development in zone C2 should not be 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.

TAN 15 goes on to state that development can only be justified in that location if it can be demonstrated that:

(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 PPW and meets the definition of previously developed land (PPW fig 2.1); and

(iv) The potential consequences of a flooding event for a particular type of development have been considered, and in terms of the criteria contained in sections 5 and 7 and appendix 1 (of TAN 15) found to be acceptable.

2.2.4 Assessment of flooding consequences Appendix 1.2 of TAN 15 states that an assessment of flooding consequences should develop a full appreciation of:

● The consequences of flooding on the development. ● The consequences of the development on flood risk elsewhere within the catchment for a range of potential flooding scenarios up to that flood having a probability of 0.1% ● The assessment can be used to establish whether appropriate mitigation measures can be incorporated within the design of the development to ensure that development minimises risk to life, damage to property and disruption to people, etc. Appendix 2 of TAN 15 recognises that flood consequences will change over time as result of climate change.

2.2.4.1 Acceptability criteria for flooding consequences Appendix 1.11 and Appendix 1.12 of TAN 15 present the main criteria for deciding whether developments in flood risk areas are acceptable in line with part (iv) of the Justification Test (see Section 2.2.3 above).

● Section A1.12 states “a site should only be considered for development if the following conditions can be satisfied; – Flood defences must be shown by the developer to be structurally adequate particularly under extreme overtopping conditions (i.e. that flood with a probability of occurrence of 0.1%) – The cost of future maintenance for all new/approved flood mitigation measures, including defences must be accepted by the developer and agreed with the Environment Agency. – The developer must ensure that future occupiers of development are aware of the flooding risks and consequences

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Mott MacDonald | Leckwith Road Site 9 Flooding Consequences Assessment

– Effective flood warnings are provided at the site – Escape/evacuation routes are shown by the developer to be operational under all conditions – Flood emergency plans and procedures produced by the developer must be in place – The development is designed by the developer to allow the occupier the facility for rapid movement of goods/possessions to areas away from the floodwaters – Development is designed to minimise structural damage during a flooding event and is flood proofed to enable it to be returned to its prime use quickly in the aftermath of the flood. – No flooding elsewhere.” ● Section A1.14 states “development should be designed to be flood-free during the 1% fluvial flood… and 0.5% tidal flood” and “there is therefore a frequency threshold of flooding below which flooding of development should not be allowed”. ● Section A1.15 of TAN 15 states “beyond the threshold frequency, proposed development would be expected to flood under extreme conditions”. TAN 15 provides indicative value for tolerable flood conditions. Value for residential developments are given in Table 2 below. Note, TAN15 does not provide figures specifically for new school developments.

Table 2: Indicative value for tolerable flood conditions (in events beyond the “threshold frequency” Type of Maximum depth Maximum rate Maximum Maximum Development of flooding of rise of flood speed of velocity of (mm) waters (m/hr) inundation of flood water flood risk (hrs) (metre/sec) Residential 600 0.1 4 0.15 Source: Section A1.15 TAN 15

2.2.5 Surface water management Section 8 of TAN 15 defines the surface water requirements for new developments, as follows: ● Surface water run-off from new developments should be managed so that the development does not increase the risk of flooding elsewhere. ● Sustainable Drainage Systems (SuDS) should be implemented, wherever they will be effective, in all new development proposals, irrespective of the Development Advice Zone in which they are located. ● The aim should be for new development not to create additional run-off when compared with the undeveloped situation, and for redevelopment to reduce run-off where possible.

Consideration must also be given to maintaining the effectiveness of any drainage systems.

2.3 Local planning policy and guidance

2.3.1 Cardiff Strategic Flood Consequences Assessment (SFCA) The main aim of the Cardiff SFCA is to provide flood risk information to inform local planning activities, including planning policy. The Cardiff SFCA is informed by the guidance outlined in TAN 15.

Cardiff has been divided into nine Sub Areas (A to I) for the purpose of the SFCA. The Leckwith Road Site is within sub-area H “Taff/Ely 2d modelled area”. The SFCA states that the flood risk

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Mott MacDonald | Leckwith Road Site 10 Flooding Consequences Assessment

to Area H can be affected by both fluvial and tidal events however flood risk is the area is “fluvially dominated”.

The Cardiff SFCA is presented as a series of technical reports. The SFCA reports relevant to the site location are:

● Cardiff Strategic Flood Consequences Assessment Phase 2 Part 1 Update Extended Development Lifetime to 2110 Areas A, G, H and I (Final Report, Revised November 2011), hereafter referred to as the “SFCA report”. ● Appendix A of the SFCA report, Area H - 0.1% annual chance fluvial predicted maximum depth 2010 map, drawing number 5097656/RCF/321 Rev A. ● Appendix A of the SFCA report, Area H - 0.1% annual chance fluvial predicted velocities 2010 map, drawing number 5097656/RCF/322 Rev A. ● Appendix A of the SFCA report, Area H - 1% annual chance tidal predicted flood extents, current and with climate change map, drawing number 5097656/RCF/320 Rev A.

2.3.2 Cardiff Local Flood Risk Management Strategy (LFRMS) and Cardiff Flood Risk Management Plan (FRMP) Cardiff Council as the Lead Local Flood Authority (LLFA) has statutory responsibility for managing the flood risk from local sources, namely surface runoff, groundwater and ordinary watercourses.

The Flood and Water Management Act 2010 requires the LLFA to produce a LFRMS and FRMP for its area. The FRMP takes forward the objectives and actions set out in the strategic framework provided by the LFRMS.

The site lies in the “Canton” area of the FRMP. The delivery plan for this area indicates a focus on Prevention (measures to reduce the number of properties identified at risk of flooding from Local Flood Risk sources) and Preparedness (community based awareness and engagement activities).

2.4 Consultation with Natural Resources Wales

2.4.1 Preliminary pre-application enquiry A pre-application enquiry was made with Natural Resources Wales (NRW). NRW responded by providing preliminary pre-application advice, and a checklist for the scope of FCA that will be required for submission with a planning application. These are included in Appendix A.1.

The preliminary NRW advice indicated that:

● The proposed development site lies within Zone C1 as defined by the Development Advice Map (DAM). ● The NRW Flood Map, confirms the site to be within the 1% (1 in 100 year) and 0.1% (1 in 1000 year) annual probability fluvial flood outlines and the 0.5% (1 in 200 year) and 0.1% (1 in 1000 year) annual probability tidal flood outlines of the River Ely. ● It will be necessary to demonstrate, through submission of a FCA, that the consequences of both tidal and fluvial flooding can be managed over the lifetime of the development. ● The impacts of climate change should be assessed for a design life of 100 years, unless agreed otherwise with the LPA. ● The site lies on 3 historic landfills and there is potential for land contamination.

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Mott MacDonald | Leckwith Road Site 11 Flooding Consequences Assessment

2.4.2 Product 4 flood data On 17 July 2017 NRW provided “Product 4” flood risk data, this includes:

Product 4 data reference number ATI-13209a ● Fluvial flood data from the Taff and Ely Velocity Depth Mapping Study (2014) for the site and 3 access routes. ● Figure 1: Current Floodmap. ● Figure 2: Depth Grid for 1%AEP (1 in 100 + 25%) year event plus Climate Change central estimate – defended. ● Figure 3: Depth Grid for 0.1%AEP (1 in 1000) year event – defended. ● Figure 4: Hazard Grid for 0.1%AEP (1 in 1000) year event – defended. ● Figure 5: Historic Floodmap.

Product 4 data reference number ATI-13209e ● Tidal flood data from the Extreme Sea Level Study (Environment Agency 2011) for the Severn Estuary, and interpolated by NRW for the site. This is included in Appendix A.2.

2.4.3 Good Practice Guide 101 – Producing flood risk hydraulic models and flood consequences assessments for development planning purposes NRW Good Practice guide “producing flood risk hydraulic models and flood consequence assessments for development planning purposes” was published September 2015. The guidance provides good practice advice for developers and their consultants preparing flood risk documentation to support development planning proposals.

GPG 101 states that a FCA or appraisal must include consideration of climate change on all coastal levels up to and including the 0.1% (1 in 1000) annual probability of occurrence. Historically, climate change has not generally been considered in conjunction with a 0.1% (1 in 1000) annual probability event, including the Cardiff SFCA.

2.4.4 Other correspondence with NRW Other relevant ad-hoc correspondence with NRW undertaken as part of this FCA, is included in Appendix A.3.

● In relation to assessment of compensatory flood storage, NRW confirmed that this should be provided for all return periods up to and including the 1000 year event. ● NRW confirmed that the tidal flooding data should be included in the FCA for completeness only. In terms of assessment of TAN15 A1.11-A1.15 criteria, this should be undertaken in relation to the dominant source of flood risk in this location (fluvial flood risk from Rivers Taff and Ely). ● The maximum predicted flood levels for a given event should be used unless there is justification to use lower values such as mean flood levels. ● NRW confirmed that TAN15 does not provide indicative value for tolerable flood conditions specifically for new school developments. For the purposes of this assessment they confirmed that the conditions provided for residential development would also apply to school developments (i.e. precautionary approach).

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2.5 Consultation with Lead Local Flood Authority (Cardiff Council)

2.5.1 Request for local flood information Cardiff Council flood risk team was contacted on 5 July 2017 and requested to provide local flood risk information for the site (Appendix B). A reply had not been received in time to inform this report.

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3 Assessment of the suitability of the site for development proposed

3.1 Development advice zone The TAN 15 Development Advice Map (DAM) indicates the extents of the Development Advice Zones for areas in Wales. The DAM indicates that the majority of the site lies within zone B however area located on the south, north and east periphery of the site lie with development advice zone C1. No areas of the site lie within development advice zone C2.

Figure 3: Extract from Development Advice Map

Source NRW Long term flood risk online map, last accessed August 2017. Red line indicates approximate site boundary. Approximate red line boundary produced Mott MacDonald 2017.Approximate red line boundary produced Mott MacDonald 2017.

3.2 Justifying the location of development in principle As previously stated in Section 2.2.3, in accordance with TAN 15, the LPA should accept the principle of a school or residential development at the site, subject to parts (i) or (ii) and (iii) and (iv) of the TAN 15 Justification Test being passed.

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4 Assessment of flooding consequences

4.1 Historical records of flooding

4.1.1 Information from NRW “Product 4” data Figure 5 of the Product 4 data provided by NRW (Appendix A.2) provides the approximate extent of flooding for the major December 1960 and December 1979 events on the River Taff. The site is not located in any of the areas indicated by Figure 5 to have been affected by historical flooding events on the River Taff.

The Product 4 data does not include any information on historical tidal flooding events.

4.1.2 Information from the Cardiff SCFA Section 2.4 of the Cardiff SFCA report states that “The Taff catchment has experienced widespread flooding on a number of occasions over the last 60 years. These include the floods of 1946/47 (due to snowmelt), December 1960, December 1979, December 1992 and October 1998, all of which were from heavy rainfall. The most notable flooding to Cardiff occurred in 1960 and 1979, where thousands of properties were affected.” It does not provide information as to whether the site was affected by any of these flood events.

This section of the report also states that “In contrast, the Ely catchment has only suffered from two significant events in the last few decades. These were a result of heavy rainfall falling on a wet catchment in March 1998 and in October 2000. The 1998 event only affected a small number of properties in the Ely Bridge area of Cardiff, St Fagans, Peterston Super Ely, Brynsadler and Talbot Green. In October 2000, few reports of flooding were reported and these were in St Fagans only.” The site is not located in any of the areas indicated by the SFCA to have been affected by historical flooding events on the River Ely.

The SCFA does not provide any information on historical tidal flood events however it does state that “Tidal flood risk is considerably lower in Cardiff since the construction of the Cardiff Bay Barrage in 1999. The barrage significantly reduces the risk of tidal flooding.”

4.2 Flooding from rivers

4.2.1 Information from NRW “Product 4” data The Product 4 data is taken from the Taff and Ely Velocity Depth Mapping (referred to as the “VDM study”) completed by Mott MacDonald on behalf of NRW in 2014. This study uses a 1D/2D linked ISIS-TUFLOW hydraulic model to assess river flooding from both the River Taff and the River Ely in Cardiff. The model consolidates information from previous studies of the Rivers Taff and Ely (namely, Ely Model Update, Atkins, 2012 & Cowbridge Road Ely Flood Modelling, Arup, 2012), utilises updated hydrology and, where required, new survey information.

The model also incorporates the risk from tide locking at the sluice gates at Cardiff Bay Barrage. For the purpose of the VDM study, the fluvial events have been predicted to coincide with a maximum level set at the mean high water spring (MHWS) level.

The Product 4 data provided flood hazard information. This has been calculated by NRW using the joint EA and DEFRA Technical Report, “Flood Risk Assessment Guidance for New Development” (report number FD2320/TR2), dated October 2005, which provides a method for

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assessing and quantifying flood hazard based on variables such as flood water depth and velocity and hazards likely to be presented by floating debris. Using this method, the hazard is classed as “Danger for some” (includes children, the elderly and the infirm), “Danger for most” (includes the general public), or “Danger for all” (includes emergency services).

The VDM study has modelled a climate change scenario in line with the latest Welsh Government climate change guidance, which comprises:

● a central fluvial climate change factor of 25% (referred to as: “Q100CCc”), and; ● a sea-level rise in the downstream boundary condition by raising levels by 1.08m (to allow for sea-level rise to the year 2115).

Table 3: Summary of key fluvial flood data for the site, assuming flood defences are in place Scenario Expected flood level in Velocity of Hazard rating metres above ordnance flood water datum (m AOD) (metre/sec) 1 in 100 year mean 7.84 0.00 0.51 “Very Low Hazard” fluvial event, plus max 7.84 (0.00) 0.51 “Very Low Hazard” allowance for climate change Current day 1 in mean 8.32 0.09 0.95 “Danger for Some” 1000 year fluvial max 8.37 0.47 1.73 “Danger to Most” event Source: NRW Product 4 data, provided in Appendix A.2. Note: the Product 4 also contains “undefended” data which is can be found in Appendix A.2.

The Product 4 data also includes information on the flood risk posed to three escape and evacuation routes, namely:

● Access 1: Lawrenny Avenue, Leckwith Road, endpoint at Leckwith Road (ST 15890 75135). ● Access 2: Lawrenny Avenue, Broad Street to Grosvenor Street, endpoint at (ST 15997 76548). ● Access 3: Lawrenny Avenue, Leckwith Road to Cowbridge Road East endpoint at (ST 16293 76595).

Table 4: Summary of key fluvial flood data for the escape and evacuation routes in 1 in 100 plus climate change event, assuming flood defences are in place. Access route Depth of flooding Velocity of flood Hazard rating number (mm) water (metre/sec) 1 mean 0.30 0.22 0.96 “Danger for Some” max 0.83 0.92 1.94 “Danger for Most” 2 mean 0.45 0.24 1.09 “Danger for Some” max 1.12 1.16 2.07 “Danger for All” 3 mean 0.47 0.40 1.28 “Danger for Most” max 1.92 1.71 2.14 “Danger for All” Source: NRW Product 4 data, provided in Appendix A.2.

Table 5: Summary of key fluvial flood data for the escape and evacuation routes in 1 in 1000 event, assuming flood defences are in place. Access route Depth of flooding Velocity of flood Hazard rating number (mm) water (metre/sec) 1 mean 0.73 0.35 1.48 “Danger for Most”

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Access route Depth of flooding Velocity of flood Hazard rating number (mm) water (metre/sec) max 1.35 1.25 2.39 “Danger for All” 2 mean 0.97 0.39 1.59 “Danger for Most” max 1.95 1.44 3.65 “Danger for All” 3 mean 0.26 0.19 0.93 “Danger for Some” max 1.67 1.67 2.01 “Danger for All” Source: NRW Product 4 data, provided in Appendix A.2.

Information relating to the 1 in 1000 year fluvial event with allowance for climate change and information on the rate of rise of flood waters or speed of inundation was not provided.

4.2.2 Information from other sources The NRW Long Term Flood Risk online map indicates that the site is within the “River Ely at Ely in Cardiff” Flood Warning and Flood Alert Area.

4.3 Flooding from the sea

4.3.1 Information from NRW “Product 4” data The Product 4 data is based on the set of national extreme sea levels published by the EA in 2011 for the baseline year of 2008. The levels were adjusted for climate change from 2008 to 2017 and projected inland over a digital terrain model to produce depth grids and outlines for both the 0.5% (1 in 200) AEP (annual exceedance probability) and the 0.1% (1 in 1000) AEP tidal events.

Table 6: Summary of key tidal flood data assuming no flood defences are in place Scenario Year Predicted flood level in metres above ordnance datum (m AOD) 1 in 200 year tidal event 2017 8.0 1 in 200 year tidal event (95% confidence bound) 2017 8.4 1 in 200 year tidal event 2117 9.1 1 in 200 year tidal event (95% confidence bound) 2117 9.5 1 in 1000 year tidal event 2017 8.4 1 in 1000 year tidal event (95% confidence bound) 2017 9.0 1 in 1000 year tidal event 2117 9.5 1 in 1000 year tidal event (95% confidence bound) 2117 10.1 Source: NRW Product 4 data, provided in Appendix A.2.

Data on rate of rise of flood waters (m/hr), speed of inundation of flood risk (hrs), velocity of flood water (metre/sec) and hazard rating were not provided.

4.3.2 Information from other sources The NRW Long Term Flood Risk online map indicates that the site is within the “Coast from Aberthaw to Severn Bridge” Flood Alert Area. The site does not benefit from a tidal flood warning service.

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4.4 Surface water flooding The NRW Long Term Flood Risk online map (reproduced in Figure 4) indicates that very small, isolated areas of the site are at “low” risk of surface water flooding. Some areas adjacent to the site, such as the junction with Leckwith Road are shown to have “medium” or “high” risk.

“Low” risk means areas that each year have a chance of flooding between 1 in 1000 (0.1%) and 1 in 100 (1%), “medium” risk means areas that each year have a chance of flooding between 1 in 100 (1%), and 1 in 30 (3.3%) and “high” risk means areas that each year have a chance of flooding of greater than 1 in 30 (3.3%).

However, the maps do not take into consideration existing positive drainage networks. The site is already developed and it is reasonable to assume that it has an existing positive drainage network. Therefore, it may be expected that this risk is not unusual or exceptional and can be mitigated by means of industry standard methods without excessive cost or time implications.

Figure 4: Surface water flood map

Source: NRW Long term flood risk online map, last accessed August 2017. Red line indicates approximate site boundary.

4.5 Flooding from sewers The LLFA, Cardiff Council, did not provide any information to inform this report.

The sewerage undertaker Dwr Cymru Welsh Water was not contacted as part of this assessment.

Flooding from sewers and drains is typically caused by blockages or hydraulic overload.

Therefore, it is reasonable to expect that the risk and consequences of flooding from sewers and drains can be mitigated by means of industry standard methods without excessive cost or time implications e.g. by designing and maintaining sewers and drainage systems in line with

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current standards and best practice, and by setting the finished floor levels within the building above the surrounding ground levels.

4.6 Groundwater flooding Groundwater flooding occurs when water levels in the ground rise above surface levels. It is most likely to occur in areas underlain by permeable rocks, called aquifers.

The Cardiff Flood Risk Management Plan (PFRA) states “There is no information on historic groundwater flooding which suggests that the risk of groundwater flooding is low in Cardiff.”

The LLFA, Cardiff Council, did not provide any information to inform this report.

We have not found any record of groundwater flooding in the vicinity of the site.

It is considered that, relative to other potential sources of flooding, the risk of flooding from groundwater at this location is low and it is reasonable to expect that it can be mitigated by means of industry standard methods without excessive cost or time implications e.g. by setting the finished floor levels within buildings above the surrounding ground levels.

4.7 Flooding from reservoirs and canals The NRW Long Term Flood Risk online map indicates that the site is within an area that could be flooded if a large reservoir were to fail and release the water it holds.

The site could be effected by the uncontrolled release of water from the Pontsticill (Taf Fechan) reservoir. Figure 5 below shows the maximum extent of flooding possible due to this reservoir. However, NRW state that this is a worst-case scenario and it is unlikely that any actual flood would be this large.

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Figure 5: Reservoir flood map

Source: NRW Long term flood risk online map, last accessed August 2017. Red line indicates approximate site boundary. Approximate red line boundary produced Mott MacDonald 2017.

The NRW Long Term Flood Risk online map further indicates that the site could be effected by flood depths between 0.3m and 2m and velocities between 0 and 0.5 m/s if this reservoir were to fail.

Flooding from reservoirs is unlikely to happen. All large reservoirs must be inspected and supervised by reservoir panel engineers. As the enforcement authority for the Reservoirs Act 1975 in Wales, NRW ensures that reservoirs are inspected regularly and that essential safety work is carried out.

However, in the unlikely event that a reservoir dam failed, a large volume of water would escape catastrophically and rapid, widespread flooding could happen.

As such the low probability but high consequences of reservoir flooding should be appropriately acknowledged and mitigated. It is recommended that this risk can be managed within acceptable limits through a Flood Warning and Evacuation Plan for the development. The plan should outline what to do in the event of a reservoir emergency and the actions to be taken in the case of such an event.

In relation to canals, there are no known canals in the vicinity of the site. It is therefore considered that the risk of flooding from the canal is nil.

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5 Development constraints and flood mitigation measures

Where consideration of a development site can be justified, the development must then meet the acceptability criteria detailed in TAN15 Section 7 and Appendix 1.

The purpose of this assessment is to identify flooding-related development constraints, and potential mitigation measures likely to be necessary to reduce the predicted flooding consequences to an acceptable level in line with TAN15 guidance, to inform an initial assessment of cost and practicability of these mitigations.

As such an assessment has only been made of the following acceptability criteria that are deemed critical to the above:

● Escape/evacuation routes are shown by the developer to be operational under all conditions. ● Development is designed to be flood free during the indicative threshold frequency for the type of development. ● Development is assessed against the indicative tolerable conditions under the extreme flooding conditions. ● Development is designed to minimise structural damage during a flooding event and is flood proofed to enable it to be returned to its prime use quickly in the aftermath of the flood. ● No flooding elsewhere. The remaining acceptability criteria are not covered as will be better assessed as part of a full FCA for a defined (detailed) development proposal:

● Flood defences must be shown by the developer to be structurally adequate particularly under extreme overtopping conditions (i.e. that flood with a probability of occurrence of 0.1%). ● The cost of future maintenance for all new/approved flood mitigation measures, including defences must be accepted by the developer and agreed with the Environment Agency (n.b. now NRW). ● Effective flood warnings are provided at the site. ● The development is designed by the developer to allow the occupier the facility for rapid movement of goods/possessions to areas away from the floodwaters.

Based on the information currently available and reviewed as part of this assessment, and subject to undertaking a full FCA for a defined development proposal, it is reasonable to expect that as a minimum the following flood mitigation and management measures would be required for the development to proceed.

5.1 Operational escape and evacuation routes As stated in Section 4.2.1, all three potential escape and evacuation routes are indicated to have an average Hazard to People Classification of “Danger for Some” or higher for the 1 in 100 year event plus climate change and above. This implies the accesses are unlikely to be safe for

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the intended occupants of a school (e.g. children) however it may be acceptable for the general public and passable for emergency services.

The maximum hazard rating for Access 1 in the 1 in 100 event plus climate change is “Danger for Most” which implies that the access is unlikely to be safe for the intended occupants of a school however it may be passable for emergency services.

The maximum hazard rating for all three possible access routes in the 1 in 1000 event is “Danger for All” which implies the access’ are unlikely to be safe for the intended occupants of a school or the emergency services.

The above demonstrates the possible escape and evacuation routes are not predicted to be operational under all conditions. It is recommended that further consultation is undertaken with NRW to assess whether this is tolerable. For the school development, this may be acceptable as it is practical to evacuate the occupants before flooding occurs. To assist with evacuation, the site is covered by the NRW Flood Warning Service.

The developer and future site occupiers should register with the NRW Flood Warnings Direct service (0845 9881188). Procedures, roles, responsibilities, and triggers for evacuating the school site should be clearly set out in an Emergency Flood Plan.

5.2 Flood free during the indicative threshold frequency To meet this TAN 15 acceptability criteria requirement, it is expected that the area around the main school building including the car park and access road will need to be at least 7.84m AOD.

Open Source Lidar data indicates that all of the site is elevated above this level and therefore it is not expected that the land would have to be raised to meet this constraint.

BS8533:2011 states that an additional “freeboard” should also be allowed for finished floor levels of buildings. It states that the minimum freeboard is generally 600 mm where there is a lack of information on which to base the flood level, or 300 mm where there is confidence in the predicted flood level. For this site, the flood levels have been derived for recent NRW hydraulic models therefore it is considered that there is good confidence in the predicted flood level.

As such for the development proposal it is recommended that the main school building should have a finished flood level of at least 8.14m AOD.

Open Source Lidar data indicates that the majority of the site is elevated above this level. If the school building were to be located in either the western segment of the site or the north-western portion of the eastern segment of the site, it is anticipated that building floor levels would only need to be elevated above existing ground levels to the normal extents required by Building Regulations. If the school building were to be located in south-eastern portion of the eastern segment of the site, then it is anticipated that the building flood levels would need to be approximately 0.2m above existing ground levels.

The assessment of minimum land and floor levels has been based on Open Source Lidar topographic data and should be verified with surveyed topographic data once available.

5.3 Tolerable conditions in extreme floods As stated in Section 2.2.4, Section A1.15 of TAN 15 states “beyond the threshold frequency, proposed development would be expected to flood under extreme conditions”. TAN 15 provides indicative value for tolerable flood conditions. Values for residential developments are given in Table 7 below.

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Table 7: Indicative value for tolerable flood conditions (in events beyond the “threshold frequency” Type of Maximum depth Maximum rate Maximum Maximum Development of flooding of rise of flood speed of velocity of (mm) waters (m/hr) inundation of flood water flood risk (hrs) (metre/sec) Residential 600 0.1 4 0.15

Source: Section A1.15 TAN 15

Given that the maximum 1 in 1000 year flood level is 8.37m AOD, and provided the area around the buildings is raised to at least 7.84m AOD and the main school buildings have a finished floor level of at least 8.14m AOD, the maximum depth of flooding in events beyond the “threshold frequency” will range between 530mm and 230mm. These are within the maximum depth tolerances provided in Section A1.15 of TAN 15 (and summarised in in Table 7).

The assessment of land raising has been based upon Open Source Lidar topographic data and should be verified with surveyed topographic data once available. We do not have the data needed to assess the other tolerances provided in TAN 15 A1.15 (replicated in Table 7), namely maximum rate of rise of flood waters, maximum speed of inundation of flood risk and maximum velocity of flood water. It is recommended that further consultation is undertaken with NRW to assess whether further hydraulic is necessary to determine these values.

5.4 Structural integrity and flood resilience TAN 15 advises to incorporate flood resilient construction measures within the proposed development to mitigate against the flooding. Flood resilient buildings are designed and constructed to reduce the impact of flood water entering the building so that no permanent damage is caused, and the building may be retried to normal use as quickly as possible following a flood event. Flood resilient measures include air brick covers, raised sockets and electrical systems or water-resistant flooring. It is recommended that the initial assessment of cost and practicability of these mitigations includes:

● Raising of floor levels for all school buildings to at least 8.14m AOD (flood proofing). ● Flood resilience measures for all school buildings or residences to at least a level of 8.37m AOD.

5.5 The development does not increase flood risk elsewhere As Section 4.2 has outlined, the site is at risk from fluvial flooding from the Rivers Taff and Ely. The construction of school or residential buildings, and raising of ground for car parking and access routes, will occupy space that would otherwise be available for the storage or conveyance of flood water.

To demonstrate that the development will not increase flood risk elsewhere, at planning application stage the FCA would need to determine the net volume of water that could be displaced by the new development located in the floodplain. Compensatory flood storage will normally need to be provided to ensure no detriment is caused as a result of the development.

As described above, any new development on the site is expected to be raised to be flood free in the 1 in 100 year plus climate change event therefore compensatory flood storage may be required to ensure flood risk does not increase elsewhere.

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An assessment of the compensatory storage will need to be undertaken whether a school or a residential development is proposed. An assessment of the scale of the requirements for compensatory storage should be progressed as early as possible in the feasibility stage. This assessment may not identify an acceptable technical solution or may demonstrate that it is not practicable to provide the compensatory storage required with respect to cost and programme.

If the school building were to be located in south-eastern portion of the eastern segment of the site, compensatory flood storage will need to be provided. If the school building were to be located in either the western segment of the site or the north-western portion of the eastern segment of the site, the need to provide significant compensatory flood storage could be avoided.

The assessment of the compensatory storage should include,

● further hydraulic modelling to assess the scale and technical feasibility of compensation required; ● further assessment of historical landfill uses and the implications or constraint for land raising or evacuation, and; ● an assessment of the availability of land in the vicinity (within site or in surrounding area) of the proposed development to accommodate anticipated compensatory flood storage requirements. It is possible that compensatory storage could be provided at the other potential school sites (Lawrenny Avenue and Fitzalan School).

5.6 Residual risks It is not possible to completely eliminate future flood risk. There is always a residual risk of flooding on any development. For this site, the risk may arise from the breach or overtopping of local fluvial or tidal flood defences or localised flooding caused by a blockage in the local drainage or watercourse systems.

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6 Conclusions and recommendations

6.1 Suitability of the site for development The construction of a school at this site may be contrary to Planning Policy Wales guidance in relation to flood risk and flooding consequences, as available escape and evacuation routes are not operational under “all conditions” and therefore the development does not meet all the acceptability criteria detailed in TAN15 Section 7 and Appendix 1.

Therefore, the development proposal will be subject to acceptance by NRW and the LPA of a departure from this guidance.

If the principle of development is accepted by the LPA then a flood consequences assessment (FCA) will need to be prepared that demonstrates that the potential consequences of flooding as a result of the development, are otherwise acceptable in terms of the criteria set out in TAN 15.

6.2 Constraints and mitigations The following flooding-related development constraints, and mitigation measures have been identified for the development proposals.

● The area around the main school building including the car park and vehicle access will need to be raised to at least 7.84m AOD. Open Source Lidar data indicates that existing ground levels are at or above this elevation. ● The main school building should have a finished flood level of at least 8.14m AOD. Open Source Lidar data indicates that the majority of the site is elevated above this level. If the school building were to be located in either the western segment of the site or the north- western portion of the eastern segment of the site, it is anticipated that building floor levels would only need to be elevated above existing ground levels to the normal extents required by Building Regulations. However, if the school building were to be located in south-eastern portion of the eastern segment of the site, then it is anticipated that the building flood levels would need to be approximately 0.2m above existing ground levels. ● Flood resilience measures should be considered for all school buildings to at least a level of 8.37 m AOD. ● If the school building were to be located in south-eastern portion of the eastern segment of the site, compensatory flood storage will need to be provided. If the school building were to be located in either the western segment of the site or the north-western portion of the eastern segment of the site, the need to provide significant compensatory flood storage could be avoided.

6.3 Qualifications and recommendations for further work to determine further flood-related constraints Although development of a school at this site is contrary to Planning Policy Wales guidance on flooding consequences, if it is established that a new or extended school is required then the risks and consequences of flooding at this site should be balanced against those at available alternative sites.

The above advice is based on the information that has been obtained and made available at the time of this assessment. Further flooding-related development constraints, and potential

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mitigation measures will be required however without further work, the extent of these measures cannot be determined. Recommendations for further work to determine these constraints and mitigations are provided below.

An assessment of the scale of the requirements for compensatory storage should be progressed as early as possible in the feasibility stage. This assessment may not identify an acceptable technical solution or may demonstrate that it is not practicable to provide the compensatory storage required with respect to cost and programme. For example, the solution could involve moving or removing significant volumes of material, remediation or inflated disposal costs of material due to historical uses (landfill) and may necessitate work on other Cardiff Council or third-party land. This assessment of flood consequences is based on a review of existing readily available information. The assessment of land raising is based upon Open Source Lidar topographic data and should be verified with surveyed topographic data once available.

In preparing an FCA for a planning application for a proposed development at this site it may be necessary to undertake additional modelling and mapping of predicted flooding consequences and associated hazards. It is also recommended that the public sewer asset location plan and flood history are obtained for the site to inform this assessment of flood risks and constraints.

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Appendices

A. Consultation with Natural Resources Wales 27 B. Consultation with Cardiff Council (LLFA) 30

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A. Consultation with Natural Resources Wales

A.1 Preliminary Pre-Planning Application Screening

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Ein cyf | Our ref: CAS-35188-H4L5, CAS-35191- V8R8, CAS-35193-C3Z6, CAS-35194-B5Y0, CAS-35195-D8K6, CAS-35199-H0W4, CAS- 35204-W9D6, CAS-35205-T4S7, CAS-35207- N2S4 Eich cyf | Your ref:

Rivers House St Mellons Business Park Fortran Road Cardiff Mott MacDonald CF3 0EY Fitzalan House Fitzalan Road Ebost | Email: Cardiff [email protected] CF24 0EL Ffôn | Phone: 03000 653 095

FAO: James Tugwell

30 June 2017

Annwyl Syr/Madam | Dear Sir/Madam,

PRELIMINARY PRE-APPLICATION ADVICE – CARDIFF COUNCIL’S 21ST CENTURY SCHOOL’S BAND B PROGRAMME – VARIOUS LOCATIONS.

Thank you for your enquiry dated 23 June 2017.

We have considered your enquiry in relation to our Development Planning checklist. We advise the following matters are relevant to your proposed developments and suggest you consider these further prior to the submission of any planning application:

A1. WILLOWS HIGH SCHOOL - ADDING A TWO FORM OF ENTRY EXTENSION TO THE EXISTING SCHOOL TO INCREASE THE CAPACITY TO AN EIGHT FORM OF ENTRY HIGH SCHOOL - WILLOWS HIGH SCHOOL, WILLOWS AVENUE, CARDIFF

Flood Risk The proposed development site lies within Zone C2 as defined by the Development Advice Map (DAM) referred to under Technical Advice Note 15: Development and Flood Risk (TAN15) (July 2004). Our Flood Map, which is updated on a quarterly basis, confirms the site to be within the 0.5% (1 in 200 year) and the 0.1% (1 in 1000 year) annual probability tidal flood outlines of the River Rhymney, a designated main river. Therefore we advise you need to demonstrate, through submission of a flood consequences assessment (FCA), the consequences of flooding can be managed over the lifetime of the development.

Please find attached a document intended to help you prepare your FCA. This document provides advice to you on the scope of your FCA (based on the information available to us). Please note, a submission in line with our advice will enable a better understanding of the risks and consequences of flooding, but will not necessarily mean the risks and consequences are demonstrated as being managed acceptably in line with TAN15. We refer you to our website for further advice.

Flood data for this area is available upon request from our Data Distribution Team. Please provide a grid reference and location plan of the site. Please use this information to inform your FCA.

European Protected Species

Tŷ Cambria 29 Heol Casnewydd Caerdydd CF24 0TP Cambria House 29 Newport Road Cardiff CF24 0TP Croesewir gohebiaeth yn y Gymraeg a’r Saesneg Correspondence welcomed in Welsh and English

Our records show there may be protected species, including bat species, within the proposed development site. We advise liaison with the Local Planning Authority ecologist to discuss and agree the scope of any surveys required. We refer you to our website for further advice.

A2. WILLOWS HIGH SCHOOL - CONSTRUCTING A NEW EIGHT FORM OF ENTRY HIGH SCHOOL ON THE EXISTING WILLOWS SITE - WILLOWS HIGH SCHOOL, WILLOWS AVENUE, CARDIFF

Flood data for this area is available upon request from our Data Distribution Team. Please provide a grid reference and location plan of the site. Please use this information to inform your FCA.

European Protected Species Our records show there may be protected species, including bat species, within the proposed development site. Furthermore, the proposal involves the demolition of the existing building on site. We advise liaison with the Local Planning Authority ecologist to discuss and agree the scope of any surveys required. We refer you to our website for further advice.

A3. WILLOWS HIGH SCHOOL - CONSTRUCTING A NEW EIGHT FORM OF ENTRY HIGH SCHOOL ON SPLOTT PARK - SPLOTT PARK, CARDIFF

Flood Risk The proposed development site lies within Zone C2 as defined by the Development Advice Map (DAM) referred to under Technical Advice Note 15: Development and Flood Risk (TAN15) (July 2004). Our Flood Map, which is updated on a quarterly basis, confirms the site to be within the 0.1% (1 in 1000 year) annual probability tidal flood outlines of the River Rhymney, a designated main river. Therefore we advise you need to demonstrate, through submission of a flood consequences assessment (FCA), the consequences of flooding can be managed over the lifetime of the development.

Flood data for this area is available upon request from our Data Distribution Team. Please provide a grid reference and location plan of the site. Please use this information to inform your FCA.

European Protected Species

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Our records show there are trees on the proposed development site and there may be protected species, including bat species, within the vicinity of the proposed development site. Furthermore, the proposal involves the demolition of the existing building on site. We advise liaison with the Local Planning Authority ecologist to discuss and agree the scope of any surveys required. We refer you to our website for further advice.

A4. WILLOWS HIGH SCHOOL - CONSTRUCTING A NEW EIGHT FORM OF ENTRY HIGH SCHOOL AND A TWO FORM OF ENTRY PRIMARY SCHOOL AT SPLOTT PARK - SPLOTT PARK, CARDIFF

Flood Risk The proposed development site lies within Zone C2 as defined by the Development Advice Map (DAM) referred to under Technical Advice Note 15: Development and Flood Risk (TAN15) (July 2004). Our Flood Map, which is updated on a quarterly basis, confirms the site to be within the 0.1% (1 in 1000 year) annual probability tidal flood outlines of the River Rhymney, a designated main river. Therefore we advise you need to demonstrate, through submission of a flood consequences assessment (FCA), the consequences of flooding can be managed over the lifetime of the development.

Flood data for this area is available upon request from our Data Distribution Team. Please provide a grid reference and location plan of the site. Please use this information to inform your FCA.

European Protected Species Our records show there are trees on the proposed development site and there may be protected species, including bat species, within the vicinity of the proposed development site. Furthermore, the proposal involves the demolition of the existing building on site. We advise liaison with the Local Planning Authority ecologist to discuss and agree the scope of any surveys required. We refer you to our website for further advice.

A5. WILLOWS HIGH SCHOOL - CONSTRUCTING A NEW EIGHT FORM OF ENTRY HIGH SCHOOL ON TREMORFA PARK - TREMORFA PARK, CARDIFF

Flood Risk The proposed development site lies within Zone C2 as defined by the Development Advice Map (DAM) referred to under Technical Advice Note 15: Development and Flood Risk (TAN15) (July 2004). Our Flood Map, which is updated on a quarterly basis, confirms the site to be within the 0.5% (1 in 200 year) and 0.1% (1 in 1000 year) annual probability tidal flood outlines of the River Rhymney, a designated main river. Therefore we advise you need to demonstrate, through submission of a flood consequences assessment (FCA), the consequences of flooding can be managed over the lifetime of the development.

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Flood data for this area is available upon request from our Data Distribution Team. Please provide a grid reference and location plan of the site. Please use this information to inform your FCA.

European Protected Species Our records show there are trees on the proposed development site and there may be protected species, including bat species, within the vicinity of the proposed development site. We advise liaison with the Local Planning Authority ecologist to discuss and agree the scope of any surveys required. We refer you to our website for further advice.

B6. FITZALAN HIGH SCHOOL - CONSTRUCTING A NEW TEN FORM OF ENTRY HIGH SCHOOL ON THE EXISTING FITZALAN SITE - FITZALAN HIGH SCHOOL, LAWRENNY AVENUE, CARDIFF

Flood Risk The proposed development site lies within Zone C1 as defined by the Development Advice Map (DAM) referred to under Technical Advice Note 15: Development and Flood Risk (TAN15) (July 2004). Our Flood Map, which is updated on a quarterly basis, confirms the site to be within the 1% (1 in 100 year) and 0.1% (1 in 1000 year) annual probability fluvial flood outlines and the 0.5% (1 in 200 year) and 0.1% (1 in 1000 year) annual probability tidal flood outlines of the River Ely, a designated main river. Therefore we advise you need to demonstrate, through submission of a flood consequences assessment (FCA), the consequences of flooding can be managed over the lifetime of the development.

Flood data for this area is available upon request from our Data Distribution Team. Please provide a grid reference and location plan of the site. Please use this information to inform your FCA.

Contamination Due to the previous use of the site as Lawrenny Avenue West historic landfill site, there is potential for land contamination. We refer you to our website for further advice.

Historic Landfill The proposed development is on Lawrenny Avenue West historic landfill site. The Environment Agency provided the Local Authority with Historic Landfill data in 2007. You may wish to consult the Local Authority’s Environmental Health department with regard to this aspect.

B7. FITZALAN HIGH SCHOOL - CONSTRUCTING A NEW TEN FORM OF ENTRY HIGH SCHOOL ON THE SITE TO THE SOUTH OF LAWRENNY AVENUE - SOUTH OF LAWRENNY AVENUE, CARDIFF

Flood Risk

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The proposed development site lies within Zone C1 as defined by the Development Advice Map (DAM) referred to under Technical Advice Note 15: Development and Flood Risk (TAN15) (July 2004). Our Flood Map, which is updated on a quarterly basis, confirms the site to be within the 1% (1 in 100 year) and 0.1% (1 in 1000 year) annual probability fluvial flood outlines and the 0.5% (1 in 200 year) and 0.1% (1 in 1000 year) annual probability tidal flood outlines of the River Ely, a designated main river. Therefore we advise you need to demonstrate, through submission of a flood consequences assessment (FCA), the consequences of flooding can be managed over the lifetime of the development.

Flood data for this area is available upon request from our Data Distribution Team. Please provide a grid reference and location plan of the site. Please use this information to inform your FCA.

Contamination Due to the previous use of the site as Lawrenny Avenue West historic landfill site, there is potential for land contamination. We refer you to our website for further advice.

B8. FITZALAN HIGH SCHOOL - CONSTRUCTING A NEW TEN FORM OF ENTRY HIGH SCHOOL ON THE SITE ADJACENT TO LECKWITH ROAD - LECKWITH ROAD, CARDIFF

Flood Risk The proposed development site lies within Zone C1 as defined by the Development Advice Map (DAM) referred to under Technical Advice Note 15: Development and Flood Risk (TAN15) (July 2004). Our Flood Map, which is updated on a quarterly basis, confirms the site to be within the 0.1% (1 in 1000 year) annual probability fluvial flood outlines and the 0.5% (1 in 200 year) and 0.1% 1 in 1000 year annual probability tidal flood outlines of the River Ely, a designated main river. Therefore we advise you need to demonstrate, through submission of a flood consequences assessment (FCA), the consequences of flooding can be managed over the lifetime of the development.

Flood data for this area is available upon request from our Data Distribution Team. Please provide a grid reference and location plan of the site. Please use this information to inform your FCA.

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Contamination Due to the previous use of the site as Lawrenny Avenue, Lawrenny Avenue East and Lawrenny Avenue West historic landfill sites, there is potential for land contamination. We refer you to our website for further advice.

Historic Landfill The proposed development is on Lawrenny Avenue, Lawrenny Avenue East and Lawrenny Avenue West historic landfill sites. The Environment Agency provided the Local Authority with Historic Landfill data in 2007. You may wish to consult the Local Authority’s Environmental Health department with regard to this aspect.

European Protected Species Our records show there are trees on the proposed development site and there may be protected species, including bat species, within the vicinity of the proposed development site. We advise liaison with the Local Planning Authority ecologist to discuss and agree the scope of any surveys required. We refer you to our website for further advice.

C9. THE COURT SPECIAL SCHOOL MOVED ONTO SITE OF MEADOWBANK SPECIAL SCHOOL - REMODEL AND EXPAND MEADOWBANK SCHOOL TO ACCOMMODATE 112 PUPILS (RECEPTION TO YEAR 6) FROM THE COURT SCHOOL - MEADOWBANK SCHOOL, COLWILL RD, CARDIFF

Flood Risk The proposed development site lies within Zone C1 as defined by the Development Advice Map (DAM) referred to under Technical Advice Note 15: Development and Flood Risk (TAN15) (July 2004). Our Flood Map, which is updated on a quarterly basis, confirms the site to be within the 0.1% (1 in 1000 year) annual probability fluvial flood outlines of the River Taff, a designated main river. Our records confirm the site previously flooded during the December 1960 flood event. Therefore we advise you need to demonstrate, through submission of a flood consequences assessment (FCA), the consequences of flooding can be managed over the lifetime of the development.

Flood data for this area is available upon request from our Data Distribution Team. Please provide a grid reference and location plan of the site. Please use this information to inform your FCA.

European Protected Species Our records show there are trees on the proposed development site and there may be protected species, including bat species, within the vicinity of the proposed development site. We advise liaison with the Local Planning Authority ecologist to discuss and agree the scope of any surveys required. We refer you to our website for further advice.

Other Matters Please note the view expressed in this letter is a response to a pre-planning enquiry only. We trust these comments will prove helpful but they should not set a precedent for any future Natural Resources Wales’ response to any formal application for planning permission or other legal consent. Such applications shall be assessed on the information submitted and regulations of relevance at that time. The details contained in this letter are based on the information available to date.

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If you have any queries on the above please do not hesitate to contact us.

Yn gywir | Yours faithfully,

Sarah Lund Ymgynghorydd Cynllunio Datblygu | Development Planning Advisor Cyfoeth Naturiol Cymru | Natural Resources Wales

Ein diben yw sicrhau bod adnoddau naturiol Cymru yn cael eu cynnal, eu gwella a’u defnyddio yn gynaliadwy, yn awr ac yn y dyfodol. | Our purpose is to ensure that the natural resources of Wales are sustainably maintained, enhanced and used, now and in the future.

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CHECKLIST : FULL Flood Consequence Assessment (FCA)

Information This checklist is intended to help you prepare your FCA. It documents our advice and action to you on the scope of your FCA. for the Please complete and send this checklist to us with any draft or completed FCA enquirer you wish to receive our advice on, as it will help us be as effective as we can be in (applicant/ responding to you. consultant/ agent) Any omission may delay our response or result in your FCA not demonstrating that the risk and consequences of flooding can be managed.

If this checklist is being used without having received our scoping advice, please tick here

Please note that a comprehensive submission will enable a better understanding but will not necessarily mean the risks and consequences of flooding could be manageable in line with TAN15. We reserve the right to request further information in future if it is needed to establish the risk and consequences of flooding.

For internal Initial enquiry use Date 23/06/17 Method (e.g. phone) Email Contact name James Tugwell Contact address Mott MacDonald, Fitzalan House, Fitzalan Road, Cardiff, CF24 0EL Contact email address [email protected] Telephone number 02920 467836 Site address Leckwith Road, Cardiff, CF11 8AP OS grid reference/NGR ST 16282 75752 Development proposal B8 Constructing a new ten form of entry high school on the site adjacent to Leckwith Road. LPA Cardiff Council

Other/notes to help scoping

Full FCA checklist

Full FCA This checklist for a full FCA is based on the technical requirements for assessing elements flooding consequences in section A1.17 of TAN15. They are summarised below, but you should also refer to the full descriptions in TAN15. Hydraulic modelling may need to be carried out as part of your submission. Natural Resources Wales does not currently have specific guidance on its website with respect to modelling. In the interim we recommend you refer to the modelling best practice guidance available on the Environment Agency’s website at: http://intranet.ea.gov/policies/environmentalwork/29629.aspx. We take a risk based approach to reviewing any modelling work.

Cross Element description For use by Natural Resources For use by Notes ref. to Wales only. enquirer A1.17 Scoping advice: evidence (applicant/ of needed? consultant/ TAN15 Yes/No (and why) agent) If no evidence included, why? 1 Location plan showing all Required Tidal and fluvial flood sources of flooding risk needs to be considered. Include localised flooding from existing drains/culverts etc. 2 Levels survey of existing Levels are required for the and proposed development existing ground level, proposed to Ordnance Datum finished floor levels and access (Newlyn) routes from the site 3 Standard and condition of Not Required flood alleviation measures already in place, and an assessment of the performance of the defences under flooding conditions 4 Access/evacuation plan Required To establish safest routes from the site and within the neighbouring streets and out of the area of flood risk identified 5 Assessment of potential Required As point 1. The risk flood sources (rivers, tidal, from tidal flooding and fluvial coastal, groundwater, flooding from the River Ely surface water, or needs to be considered. combination, etc) 6 A plan of the site showing Required Flood depths, any existing information on velocities, rate of rise and speed extent and depth of flood of inundation for all fluvial and events or on flood tidal flood events (plus predictions allowances for climate change) where applicable, must be provided (where available). http://gov.wales/topics/planning/ policy/policyclarificationletters/2

016/cl-03-16-climate-change- allowances-for-planning- purposes/?lang=en 7 A plan and description of Not Required any structures which may influence local hydraulics 8 Assessment of probability Required These will inform the and trends of flooding design of the development and (extent, depths, routes, etc) also any supportive Emergency Flood Plan 9 Cross-sections of the Not Required proposed development relative to the source of flooding 10 Assessment of likely rate or Required speed and duration of flooding 11 Assessment of implications Not Required of drains/sewers (existing/proposed) during flood events 12 Volume of water displaced Required Yes – If the proposed and runoff from the site site is being raised above flood following development levels as mitigation. There must be no increase in flooding elsewhere up to and including the 0.1% (1 in 1000 year) event. The surface water runoff must not be increased post development 13 Assessment of impact of Required It will be important to any displaced water assess the impact of any new elsewhere built development on the storage of fluvial flood water in this specific area 14 Assessment of impact on Not Required fluvial and coastal morphology 15 Assessment of the impacts Required In accordance with of climate change for the current guidance i.e. FCDPAG3 design life of proposed Supplementary note for development Operating Authorities (PAG) issued in October 2006 and endorsed by WAG for use in the development planning context in July 2007. 100 years lifetime of development to be used (unless an alternative figure is agreed with the appropriate local authority) 16 Assessment of residual Required if applicable risks after construction of defences (e.g. maintenance) 17 Clear and comprehensive Yes summary

Hydraulic model and Advise whether Natural modelling report - Resources Wales model is If Natural Resources available and any other advice Wales hydraulic model on modelling: used, please submit model control sheet. Model data at this location is available from: Data Distribution Please ensure all material Team, NRW, Rivers House, St has been submitted (to Mellons Business Park, Cardiff avoid delays in obtaining CF3 0EY information) and indicate datadistribution@naturalresourc how the model has been eswales.gov.uk submitted e.g. CD. Any additional elements Advise what they are and why they are needed:

Any FCA should include the following points:

Awareness of flood risk: The developer must ensure that future occupiers of the development are aware of the flooding risks and consequences. The development should be designed to allow the occupier the facility for rapid movement of goods/ possessions away from the areas of floodwaters.

Escape routes/ emergency evacuation: TAN15 states that escape/evacuation routes should be demonstrated by the developer to be operational under all conditions (see paragraph A1.12).

Structural integrity of the building: You may wish to consider whether the flood risk to the structural integrity of buildings can be managed. We advise that you should seek advice from your Building Regulations Team/ Structural Engineers. Consideration should also be given to flood resilience and resistance measures and whether these measures should be incorporated into the design of the building.

Flood warning: We encourage the applicant and future occupiers to register on our

Flood Warnings Direct service (0845 9881188) Our website also provides useful practical information on flood preparation www.naturalresourceswales.gov .uk

Does your FCA satisfy the following acceptability criteria in TAN15?

Appendix 1 Paragraph A1.12, A1.14 and A1.15

Note space for use by enquirer Have you ensured…… (applicant/ consultant/ agent)

Flood defences must be shown by the developer to be structurally adequate, particularly under extreme overtopping conditions (i.e. that flood with a probability of occurrence of 0.1%)

The cost of future maintenance for all new/approved flood mitigation measures, including defences, must be accepted by the developer and agreed with Natural Resources Wales

The developer must ensure that future occupiers of the development are aware of the flooding risks and consequences

Effective flood warnings are provided at the site

Escape/evacuation routes are shown by the developer to be operational under all conditions

Flood emergency plans and procedures produced by the developer must be in place

The development is designed by the developer to allow the occupier the facility for rapid movement of goods/possessions to areas away from the floodwaters

Development is designed to minimise structural damage during a flooding event and is flood proofed to enable it to be returned to its prime use quickly in the aftermath of the flood

No flooding elsewhere

Development is designed to be flood free during the indicative threshold frequency for the type of development

Development is assessed against the indicative tolerable conditions under extreme flooding conditions

Mott MacDonald | Leckwith Road Site 28 Flooding Consequences Assessment

A.2 “Product 4” data

380206 | 009 | A | 8 September 2017 http://pims01/pims/llisapi.dll/properties/2119390873

ATI–13209a – Pwll Coch School

E: 316249 N: 175742

1.0 Current Flood Map Figure 1 shows the current Flood Map (version 201707) at this location. The flood map represents a combination of the undefended fluvial and tidal flood extents derived from detailed local models and national generalised model data. Undefended scenarios are provided as being a possible worst case scenario in the event of defence failure.

In Cardiff the risk from river flooding has recently been assessed by the local flood risk mapping study summarised in Section 2.0 below.

More information on the Flood Map can be obtained from the Natural Resources Wales website http://www.naturalresources.wales/floodriskmap

2.0 Local Flood Risk Mapping Study

Taff and Ely Velocity Depth Mapping Study The results summarised below are taken from the Taff and Ely Velocity Depth Mapping, or ‘VDM’,study (v2.2 & v2.3). The v2.2 was undertaken by Mott MacDonald in 2014 (ref 4). This study uses a 1D/2D linked ISIS- TUFLOW hydraulic model to assess river flooding from both the River Taff and the River Ely in Cardiff. The model consolidates information from previous studies of the Rivers Taff and Ely (namely, Ely Model Update, Atkins, 2012 & Cowbridge Road Ely Flood Modelling, Arup, 2012), utilises updated hydrology and, where required, new survey information.

The model also incorporates Cardiff Bay and the risk from tide locking at the sluice gates at Cardiff Bay Barrage. For the purpose of this study the fluvial events have been predicted to coincide with a maximum level set at the mean high water spring (MHWS) level. Additional scenarios have been run to simulate a 1 in 200year tide against a number of fluvial flows (resulting in tide locking for 1.5hours longer than the MHWS cycle) and this information is available on request.

For the climate change scenario, sea-level rise has been incorporated into the downstream boundary condition by raising levels by 1.08m (to allow for sea-level rise to the year 2115).

In August 2016 Welsh Government updated the Climate Change allowances for planning purposes which will be adopted into FCAs. NRW are expected to use these climate projections from 1st December 2016. NRW re-ran the Taff and Ely VDM model to include the new climate change scenarios which are summarised in the results below (v2.3)*.

Guidance documents are available via the following link: http://gov.wales/topics/planning/policy/policyclarificationletters/2016/cl-03-16-climate-change-allowances-for- planning-purposes/?lang=en

*Note: Climate Change factor 25% will be termed Q100CCc (Climate Change central estimate) Climate Change factor 70% will be termed Q100CCu (Climate Change upper estimate)

Page 1 of 6 Model Results - the Site Shapes drawn around the site and access routes were used to query the height, depth, velocity and hazard grids to provide the results in Tables 1-8. NULL indicates site is flood free during this scenario.

Depth grids for the defended 1 in100 year plus climate change central estimate (+25%) and 1 in 1000 year events are reproduced in Figures 2 & 3 for the site.

The defended 1 in 1000 year event hazard grid is represented in Figure 4. The hazard rating below relates to the Hazard to People Classification using the hazard matrix (ref.5).

Flood Hazard Colour Hazard to People Classification Rating (HR) Code Less than 0.75 Very low hazard – Caution 0.75 to 1.25 Danger for some – includes children, the elderly and the infirm 1.25 to 2.0 Danger for most – includes the general public More than 2.0 Danger for all – includes the emergency services

Table 1 Defended Level Data Defended

1 in 1 in 1 in 1 in 1 in 1 in 1 in 1 in 1 in 2 1in 5 10 30 50 75 100 100CCc 200 1000

Model Grid Size (m) 4 4 4 4 4 4 4 4 4 4 Wet Cells 0 0 0 0 0 0 0 1 0 305 Elevation, mean NULL NULL NULL NULL NULL NULL NULL 7.84 NULL 8.32 (mAOD) Elevation, max NULL NULL NULL NULL NULL NULL NULL 7.84 NULL 8.37 (mAOD) Depth, mean (m) NULL NULL NULL NULL NULL NULL NULL 0.02 NULL 0.31 Depth, max (m) NULL NULL NULL NULL NULL NULL NULL 0.02 NULL 1.46 Velocity, mean (m/s) NULL NULL NULL NULL NULL NULL NULL 0.00 NULL 0.09 Velocity, max (m/s) NULL NULL NULL NULL NULL NULL NULL 0.00 NULL 0.47 Hazard, mean NULL NULL NULL NULL NULL NULL NULL 0.51 NULL 0.95 Hazard, max NULL NULL NULL NULL NULL NULL NULL 0.51 NULL 1.73

Table 2 Site Undefended Level Data Undefended 1 in 1 in 100 1000 Model Grid Size (m) 4 4 Wet Cells 0 697 Elevation, mean NULL 8.74 (mAOD) Elevation, max NULL 8.74 (mAOD) Depth, mean (m) NULL 0.45 Depth, max (m) NULL 1.98 Velocity, mean (m/s) NULL 0.12 Velocity, max (m/s) NULL 0.70 Hazard, mean NULL 1.05 Hazard, max NULL 1.99

Page 2 of 6 Model Results – Emergency Access to Site

Table 3 Defended Level Data for Access 1 Defended

1 in 1 in 1 in 1 in 1 in 1 in 1 in 1 in 1 in 2 1in 5 10 30 50 75 100 100CCc 200 1000

Model Grid Size (m) 4 4 4 4 4 4 4 4 4 4 Wet Cells 0 0 0 0 0 0 0 1126 549 1391 Elevation, mean NULL NULL NULL NULL NULL NULL NULL 7.86 7.73 8.36 (mAOD) Elevation, max NULL NULL NULL NULL NULL NULL NULL 8.17 8.05 8.65 (mAOD) Depth, mean (m) NULL NULL NULL NULL NULL NULL NULL 0.30 0.22 0.73 Depth, max (m) NULL NULL NULL NULL NULL NULL NULL 0.83 0.72 1.35 Velocity, mean (m/s) NULL NULL NULL NULL NULL NULL NULL 0.22 0.16 0.35 Velocity, max (m/s) NULL NULL NULL NULL NULL NULL NULL 0.92 0.82 1.25 Hazard, mean NULL NULL NULL NULL NULL NULL NULL 0.96 0.81 1.48 Hazard, max NULL NULL NULL NULL NULL NULL NULL 1.94 1.64 2.39

Table 4 Site Undefended Level Data for Access 1 Undefended 1 in 1 in 100 1000 Model Grid Size (m) 4 4 Wet Cells 64 1436 Elevation, mean 7.28 8.75 (mAOD) Elevation, max 7.29 8.85 (mAOD) Depth, mean (m) 0.14 1.08 Depth, max (m) 0.29 1.75 Velocity, mean (m/s) 0.12 0.29 Velocity, max (m/s) 0.41 1.01 Hazard, mean 0.63 1.66 Hazard, max 1.09 2.35

Page 3 of 6 Table 5 Defended Level Data for Access 2 Defended

1 in 1 in 1 in 1 in 1 in 1 in 1 in 1 in 1 in 2 1in 5 10 30 50 75 100 100CCc 200 1000

Model Grid Size (m) 4 4 4 4 4 4 4 4 4 4 Wet Cells 0 0 0 0 0 0 0 1017 0 1315 Elevation, mean NULL NULL NULL NULL NULL NULL NULL 7.52 NULL 8.24 (mAOD) Elevation, max NULL NULL NULL NULL NULL NULL NULL 7.82 NULL 8.32 (mAOD) Depth, mean (m) NULL NULL NULL NULL NULL NULL NULL 0.45 NULL 0.97 Depth, max (m) NULL NULL NULL NULL NULL NULL NULL 1.12 NULL 1.95 Velocity, mean (m/s) NULL NULL NULL NULL NULL NULL NULL 0.24 NULL 0.39 Velocity, max (m/s) NULL NULL NULL NULL NULL NULL NULL 1.16 NULL 1.44 Hazard, mean NULL NULL NULL NULL NULL NULL NULL 1.09 NULL 1.59 Hazard, max NULL NULL NULL NULL NULL NULL NULL 2.07 NULL 3.65

Table 6 Site Undefended Level Data for Access 2 Undefended 1 in 1 in 100 1000 Model Grid Size (m) 4 4 Wet Cells 646 1587 Elevation, mean 7.29 8.84 (mAOD) Elevation, max 7.30 8.92 (mAOD) Depth, mean (m) 0.54 1.34 Depth, max (m) 1.01 2.52 Velocity, mean (m/s) 0.31 0.34 Velocity, max (m/s) 1.29 1.66 Hazard, mean 1.25 1.83 Hazard, max 1.60 4.09

Page 4 of 6 Table 7 Defended Level Data for Access 3 Defended

1 in 1 in 1 in 1 in 1 in 1 in 1 in 1 in 1 in 2 1in 5 10 30 50 75 100 100CCc 200 1000

Model Grid Size (m) 4 4 4 4 4 4 4 4 4 4 Wet Cells 0 0 0 0 0 0 0 79 0 179 Elevation, mean NULL NULL NULL NULL NULL NULL NULL 8.08 NULL 8.11 (mAOD) Elevation, max NULL NULL NULL NULL NULL NULL NULL 8.12 NULL 8.30 (mAOD) Depth, mean (m) NULL NULL NULL NULL NULL NULL NULL 0.47 NULL 0.26 Depth, max (m) NULL NULL NULL NULL NULL NULL NULL 1.92 NULL 1.67 Velocity, mean (m/s) NULL NULL NULL NULL NULL NULL NULL 0.40 NULL 0.19 Velocity, max (m/s) NULL NULL NULL NULL NULL NULL NULL 1.71 NULL 1.67 Hazard, mean NULL NULL NULL NULL NULL NULL NULL 1.28 NULL 0.93 Hazard, max NULL NULL NULL NULL NULL NULL NULL 2.14 NULL 2.01

Table 8 Site Undefended Level Data for Access 3 Undefended 1 in 1 in 100 1000 Model Grid Size (m) 4 4 Wet Cells 0 354 Elevation, mean NULL 8.49 (mAOD) Elevation, max NULL 8.74 (mAOD) Depth, mean (m) NULL 0.39 Depth, max (m) NULL 2.50 Velocity, mean (m/s) NULL 0.19 Velocity, max (m/s) NULL 1.66 Hazard, mean NULL 1.06 Hazard, max NULL 5.15

3.0 Defences There are formal defences throughout the study area; on the River Taff these defences typically have a Standard of Protection in excess of 1 in 100 years as shown by the Area Benefitting from Defences in the Flood Map.

4.0 Additional Information The historic outlines provided in Figure 5 have been derived from plans showing the approximate extent of flooding for the major December 1960 and December 1979 events on the River Taff.

The local authority may be able to provide information on issues such as localised flooding from sewers, drains and culverts.

Page 5 of 6 5.0 References 1. Department for Environment, Food and Rural Affairs, 2011. Technical Report Design sea levels. R&D Report SC060064. Defra/Environment Agency 2. Flood and Coastal Defence Appraisal Guidance: FCDPAG3 Economic Appraisal. Supplementary Note to Operating Authorities – Climate Change Impacts; October 2006; Department for Environment, Food and Rural Affairs. 3. Using the national coastal flood boundary data for England and Wales, Environment Agency Operational Instruction 490_11, Issued 4/2/2011 4. River Taff and Ely at Cardiff VDM v2.2, Mott McDonald (2014) 5. Supplementary note on flood hazard ratings and thresholds for development planning and control purpose. FD2320/TR2, May 2008.

Notes The scope of the model is the mapping of flood risk, it is not intended for detailed design. The model should be considered as the starting point for more detailed modelling, commensurate with the consequences of flooding at the site of interest.

NRW models are available under licence agreement for the purpose of further development. Contact Natural Resources Wales at [email protected] for details of terms, conditions and pricing.

If the data is used in support of an FCA, please include the reference number.

NRW accept no responsibility for the selection of the access route.

Please refer to NRW standard terms and conditions.

Flood Risk Analysis 17/07/2017

Page 6 of 6 Legend Site

! ! ! ! ! ! ! ! ! ! ! Defences Main Rivers Areas Benefiting Access 2 from Defences Flood Storage Areas Flood Zone 3 Flood Zone 2

Access 1

Site

Project

Pwll Coch School, CF11 8BR [Ref: ATI-13209a]

Drawing Figure 1: Access 3 Current Floodmap [v201707]

± Date 17 Jul 2017

Scale 1:10,000 Legend Site Q100+CCc Depth (m) 0 - 0.3 Access 2 > 0.3 > 0.6 > 1.0 > 2.0

Access 1

Site

Project

Pwll Coch School, CF11 8BR [Ref: ATI-13209a]

Drawing Figure 2: Access 3 Depth Grid for 1% AEP (1 in 100 + 25%) year event plus Climate Change central estimate - defended ± Date 17 Jul 2017

Scale 1:10,000 Legend Site Q1000 Depth (m) 0 - 0.3 Access 2 > 0.3 > 0.6 > 1.0 > 2.0

Access 1

Site

Project

Pwll Coch School, CF11 8BR [Ref: ATI-13209a]

Drawing Figure 3: Access 3 Depth Grid for 0.1% AEP (1 in 1000) year event - defended

± Date 17 Jul 2017

Scale 1:10,000 Legend Site Q1000 Hazard

< 0.75 Access 2 0.75 - 1.25 1.25 - 2.0 > 2.0

Access 1

Site

Project

Pwll Coch School, CF11 8BR [Ref: ATI-13209a]

Drawing Figure 4: Access 3 Hazard Grid for 0.1% AEP (1 in 1000) year event - defended

± Date 17 Jul 2017

Scale 1:10,000 Legend Site Historic Flood Map

Access 2

Access 1

Site

Project

Pwll Coch School, CF11 8BR [Ref: ATI-13209a]

Drawing Figure 5: Access 3 Historic Floodmap (v201707)

± Date 17 Jul 2017

Scale 1:10,000 ATI-13209e – Fitzalan High School E: 315918 N: 175950

1.0 Current Flood Map

Figure 1 shows the current Flood Map (version 201707) at this location. The Flood Map represents the undefended fluvial and tidal flood extents derived from a combination of detailed and generalised modelled data.

The current tidal flood map in this area was updated by NRW in 2013. This mapping study uses sea levels from within the Severn Estuary, based on the set of extreme sea levels published by the EA in 2011 (ref2) for the baseline year of 2008. The levels were adjusted for climate change from 2008 to 2013 (+17.5mm), projected inland over a digital terrain model to produce elevation and depth grids as well as outlines for both the 0.5% (1 in 200) AEP (annual exceedance probability) and the 0.1% (1 in 1000) AEP tidal events.

More information on the Flood Map can be obtained from the Natural Resources Wales website http://www.naturalresources.wales/floodriskmap.

2.0 Extreme Sea Levels & Climate Change Guidance

Sea levels used in this projection model come from a nationally consistent set of extreme sea levels (ref 2). These levels were derived using a tidal model calibrated to UK tidal gauge data. The model output is provided for node locations spaced at approximately 2km. 95% confidence bounds for these values were also derived using the confidence intervals for each node location. The extreme sea levels comprise still water level including storm surge, however they do not account for local wave action. The baseline estimations are for the year 2008, so climate change is calculated relative to this year, for example add 28mm for the year 2016.

Extreme sea levels for the node points closest to the site location are included in Table 1 for a range of return periods (events) e.g. T100 is the 1 in 100 year return period tide, which is equivalent to the 1% AEP (Annual Exceedance Probability). The node locations are shown in Figure 2.

Table 1: 2008 Baseline Extreme Sea Levels for adjacent nodes Extreme Event Sea Level (mAOD) Node Easting Northing T25 T50 T75 T100 T200 T1000 414 318818 170758 7.57 7.69 7.77 7.83 7.97 8.37 416 318686 169326 7.51 7.63 7.71 7.77 7.91 8.33

To provide the estimate of extreme sea levels for the site (Table 2), levels were interpolated from the adjacent nodes.

Table 2: 2008 Baseline Extreme Sea Levels interpolated between adjacent nodes Extreme Event Sea Level (mAOD) Node Easting Northing T25 T50 T75 T100 T200 T1000 Site 315918 175950 7.55 7.67 7.75 7.81 7.95 8.35 95% Confidence Bound (+/- m): 0.20 0.20 0.30 0.30 0.40 0.60 Combined Level (inc 95%): 7.75 7.87 8.05 8.11 8.35 8.95

The current guidance on climate change from DEFRA is as follows:

Table 3: Sea level rise, mm per year Assumed vertical land 1990-2025 2025-2055 2055-2085 2085-2115 movement -0.5 3.5 8.0 11.5 14.5

The calculated future extreme sea levels are shown in Table 4 and 5.

Table 4: Design Scenario (excluding 95% Confidence Bound) Extreme Event Sea Year Sea level rise(m) Level (mAOD) T200 T1000 2017 0.032 8.0 8.4 2092 0.746 8.7 9.1 2117 1.109 9.1 9.5

Table 5: Sensitivity Scenario (including 95% Confidence Bound) Extreme Event Sea Year Sea level rise(m) Level (mAOD) T200 T1000 2017 0.032 8.4 9.0 2092 0.746 9.1 9.7 2117 1.109 9.5 10.1

Table 5 shows the figures when adopting a precautionary approach as advised by Agency guidance (ref 4), these levels include the upper level 95% confidence bound.

3.0 Additional Information

The local authority may be able to provide information on issues such as localised flooding from sewers, drains and culverts.

4.0 References

1. Tidal Flood Mapping Study (Penarth and Chepstow), Study report Issue 1, Atkins July 2008 2. Department for Environment, Food and Rural Affairs, 2011. Technical Report Design sea levels. R&D Report SC060064. Defra/Environment Agency 3. Flood and Coastal Defence Appraisal Guidance: FCDPAG3 Economic Appraisal. Supplementary Note to Operating Authorities – Climate Change Impacts; October 2006; Department for Environment, Food and Rural Affairs. 4. Using the national coastal flood boundary data for England and Wales, Environment Agency Operational Instruction 490_11, Issued 4/2/2011

5.0 Notes

Undefended scenarios are provided as being a possible worst case scenario in the event of defence failure. They are used as the basis of the Flood Map.

Extreme sea levels provided as part of this project are accurate to one decimal place (Table 4). Two decimal places have been provided to show the gradual change between nodes seen in the model, however, this does not imply greater accuracy.

The scope of the model is the mapping of flood risk, it is not intended for detailed design.

The model should be considered as the starting point for more detailed modelling, commensurate with the consequences of flooding at the site of interest.

NRW models are available under licence agreement for the purpose of further development. Contact Natural Resources Wales Data Distribution team for details of terms, conditions and pricing.

If the data is used in support of an FCA, please include the reference number. Please refer to NRW standard terms and conditions.

Flood Risk Analysis 25/07/2017

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Contact: Ffôn / Tel: 0300 065 3000, E-bost / E-mail: [email protected] / [email protected] Mott MacDonald | Leckwith Road Site 29 Flooding Consequences Assessment

A.3 Other correspondence

380206 | 009 | A | 8 September 2017 http://pims01/pims/llisapi.dll/properties/2119390873

Haines, Natalie

Fr o m : Llewellyn, Carl Sen t : 26 July 2017 15:20 To: Haines, Natalie Su b j ect : RE: ATI13209C Flood Product 4 Invoice Fitzalan High School, CF11 8XB

It should be for all return periods up to and including the 1000 year event

Regar d s

Eich Enw/ Carl Llewellyn Teitl swydd/ Dadansoddiad Risg Llifogydd / Flood Risk Analysis Cyfoeth Naturiol Cymru / Natural Resources Wales Ffôn/Tel: 03000 653092 E-bost/E-mail: [email protected]

On 23rd August 2016 the Welsh Government published a Policy Clarification Letter regarding climate change allowances for planning purposes, supplemented by a guidance note and map. The letter and supporting documents supplement the policy advice provided in Technical Advice Note (TAN) 15: Development and Flood Risk. Local planning authorities, applicants and their consultants are expected to use these climate projections from 1st December 2016.

The documents are available via the following link: http://gov.wales/topics/planning/policy/policyclarificationletters/2016/cl-03-16-climate-change-allowances- for-planning-purposes/?lang=en

Fr o m : Haines, Natalie [mailto:[email protected]] Se n t : 26 July 2017 14:59 To: Llewellyn, Carl Su b j e ct : RE: ATI13209C Flood Product 4 Invoice Fitzalan High School, CF11 8XB

Hi Carl Thanks providing the attached … however it doesn’t confirm the return period for the calculation …. Natalie

Fr o m : Llewellyn, Carl [mailto:[email protected]] Se n t : 26 July 2017 14:53 To: Haines, Natalie Su b j e ct : RE: ATI13209C Flood Product 4 Invoice Fitzalan High School, CF11 8XB

See attached for clarity

Regar d s

Eich Enw/ Carl Llewellyn Teitl swydd/ Dadansoddiad Risg Llifogydd / Flood Risk Analysis

1 Cyfoeth Naturiol Cymru / Natural Resources Wales Ffôn/Tel: 03000 653092 E-bost/E-mail: [email protected]

The documents are available via the following link: http://gov.wales/topics/planning/policy/policyclarificationletters/2016/cl-03-16-climate-change-allowances- for-planning-purposes/?lang=en

Fr o m : Haines, Natalie [mailto:[email protected]] Se n t : 26 July 2017 14:47 To: Llewellyn, Carl Su b j e ct : RE: ATI13209C Flood Product 4 Invoice Fitzalan High School, CF11 8XB

Hi Carl Sorry to bother you again but can you confirm that in terms of compensatory flood storage for these sites, NRW would only expect this to be calculated on a “volume-for-volume” basis (rather than “level-for-level”) up to the 1 in 100 +CC event Thanks, Nat al i e

Fr o m : Llewellyn, Carl [mailto:[email protected]] Se n t : 25 July 2017 14:11 To: Haines, Natalie Su b j e ct : RE: ATI13209C Flood Product 4 Invoice Fitzalan High School, CF11 8XB

Aft ernoon Nat alie

Yes t h at i s co r r e ct

Regar d s

Eich Enw/ Carl Llewellyn Teitl swydd/ Dadansoddiad Risg Llifogydd / Flood Risk Analysis Cyfoeth Naturiol Cymru / Natural Resources Wales Ffôn/Tel: 03000 653092 E-bost/E-mail: [email protected]

The documents are available via the following link:

2 http://gov.wales/topics/planning/policy/policyclarificationletters/2016/cl-03-16-climate-change-allowances- for-planning-purposes/?lang=en

Fr o m : Haines, Natalie [mailto:[email protected]] Se n t : 25 July 2017 14:07 To: Llewellyn, Carl Su b j e ct : RE: ATI13209C Flood Product 4 Invoice Fitzalan High School, CF11 8XB

Thanks for this and the call Carl. Based on our discussion, we will use the tidal data in the FCA for completeness only. In terms of assessment of TAN15 A1.11-A1.15 criteria, this should be undertaken in relation to the dominant source of flood risk in this location (fluvial flood risk from Rivers Taff and Ely). Please can you confirm my understanding, thanks Natalie

Fr o m : Llewellyn, Carl [mailto:[email protected]] Se n t : 25 July 2017 12:19 To: Haines, Natalie Su b j e ct : RE: ATI13209C Flood Product 4 Invoice Fitzalan High School, CF11 8XB

As discussed

Eich Enw/ Carl Llewellyn Teitl swydd/ Dadansoddiad Risg Llifogydd / Flood Risk Analysis Cyfoeth Naturiol Cymru / Natural Resources Wales Ffôn/Tel: 03000 653092 E-bost/E-mail: [email protected]

The documents are available via the following link: http://gov.wales/topics/planning/policy/policyclarificationletters/2016/cl-03-16-climate-change-allowances- for-planning-purposes/?lang=en

Fr o m : Haines, Natalie [mailto:[email protected]] Se n t : 20 July 2017 15:32 To: Llewellyn, Carl Cc: Price, Nicholas M Su b j e ct : FW: ATI13209C Flood Product 4 Invoice Fitzalan High School, CF11 8XB

Hi Carl

I understand Nick discussed the issue I have been trying to resolve with regards to the flood data for the Fitzalan High Sc h o o l si t e .

3 Please see full email chain below (from both Michell Lewis and Paul Morris), but to summarise: - the FCA screening stated the site was at risk from both fluvial and tidal flooding sources, as also confirmed by the Car d i f f SFCA. - the product 4 data issued on 17/ 7 provided only fluvial data - I subsequently requested the corresponding tidal data - today I received a reply saying that the data (as part of the Cardiff VDM study) was available but would have to purchase an additional P4 - similarly to Nick’s situations for his sites, the P4 data issued does not contain any information on the 1000+CC.

Although I have not started work on the other site adjacent to Fitzalan (Sanatorium Park and Pwll Coch, P4 ref: at i13209c and at i13209b) I have just scanned t he P4 dat a and see t he same issue applies t o t hese as well.

Any assistance much appreciated Thanks, Nat al i e

Natalie Haines (née Newton) IEng MICE Engineering Project Manager

D +44 (0)29 2046 7871 T +44 (0)29 2046 7800 F +44 (0)29 2047 1888 [email protected]

Mott MacDonald Fitzalan House Fitzalan Road Cardiff CF24 0EL United Kingdom

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Mott MacDonald Limited. Registered in England and Wales no. 1243967. Registered office: Mott MacDonald House, 8- 10 Sydenham Road, Croydon CR0 2EE, United Kingdom The information contained in this e-mail is intended only for the person or entity to which it is addressed and may contain confidential and/or privileged material. If you are not the intended recipient of this e-mail, the use of this information or any disclosure, copying or distribution is prohibited and may be unlawful. If you received this in error, please contact the sender and delete the material from any computer.

Fr o m : Morris, Paul [mailto:[email protected]] Se n t : 20 July 2017 11:11 To: Haines, Natalie Cc: Llewellyn, Carl Su b j e ct : RE: ATI13209C Flood Product 4 - Fitzalan High School, CF11 8XB

Hi Nat alie,

Our Data Distribution team has been in contact with regards to a Product 4 request for the above school. From the correspondence, I can see that you’re preparing an FCA to support the potential redevelopment of this site as well as other similar sites within Cardiff. I understand you have had P4 responses to some of these requests for data including one for the above school.

4 You raised a query about the risk of tidal flooding to the above site based on the data from the Cardiff SFCA study for Area H. I’ve checked our Taff & Ely VDM study which represents our best available information within the area. As stated in the ATI P4 report, the model was run for additional scenarios to simulate an extreme tidal event in combination with an extreme fluvial event. For example, the 1 in 200 year (defended) tidal scenario has been combined with the 1 in 30 year, the 1 in 100 year and the 1 in 1000 year (defended) fluvial scenarios on both the Taff and Ely. There’s also a 1 in 200 year + CC (defended) tidal scenario combined with both the 1 in 100 year + 20%* (defended) fluvial scenarios again on the Taff and Ely. *Please note that this hasn’t been updated according to the new WG climate change allowances for planning purposes.

We can provide this additional information on request as a separate Product 4 or provide the raw data as a Product 6. Alternatively, we could provide the model as a Product 7 (list of products attached).

We would advise that this model is more appropriate for detailed decision making going forward. The Cardiff SFCA model is available but, as it is a strategic study, is not warranted for other purposes.

You may wish to speak to Carl Llewellyn who is the Development of Flood Risk officer for Cardiff (carl.llewellyn@nat uralresourceswales.gov.uk or 0300 065 3092) for further advice on this.

Ki nd r egar ds, Paul .

Paul M or r i s Dadansoddiad Risg Llifogydd/Flood Risk Analysis Cyfoeth Naturiol Cymru /Natural Resources Wales

Ff ôn al l annol /External Tel :03000 653 100 Ff ôn mew nol /Internal Tel: 3100 E- b o st /E-mail: [email protected]

Fr o m : Haines, Natalie Se n t : 19 July 2017 12:13 To: 'Data Distribution' Su b j e ct : RE: ATI13209C Flood Product 4 Invoice Fitzalan High School, CF11 8XB

Hi Michelle I’m sorry to persist ….. but I have also already checked the SFCA (obtained from Cardiff Council’s website) . The site is in Area H of the SFCA and is considered to be at risk for tidal flooding, as shown by the tidal flood extent map at t ached. As stated previously, the documents published Cardiff Council’s website do not provide the level, velocity, depth etc data I need for the FCA for the site. I believe this is data that NRW hold on behalf of the council, hence my request for it to be included in the Product 4. Natalie

Fr o m : Data Distribution [mailto:[email protected]] Se n t : 19 July 2017 11:48 To: Haines, Natalie Su b j e ct : RE: ATI13209C Flood Product 4 Invoice Fitzalan High School, CF11 8XB

Dear Miss Haines,

5 Further to your email, sites within the Taff/Ely catchments within Cardiff are covered mainly from our Taff & Ely VDM study, whereas it tends to vary for sites within Rhymney catchment and other parts of Cardiff. For example, the Tremorfa site is covered by the Cardiff SFCA (Area A). This study was generated on behalf of Cardiff County Council at a strategic level, and so the scope and detail of both models differ. This is reflected in our Product 4 reports.

I trust this is useful to you.

Yours sincerely,

Michelle

Eich Enw/Your name: Michelle Lewis Teitl Swydd/Job Title: Swyddog Cysylltiadau Allanol/ External Relations Officer Teitl eich tim/Title of your team: Cysylltiadau Allanol/External Relations Cyfoeth Naturiol Cymru/Natural Resources Wales Ffon/Tel: VOIP: 03000653577 or Ganolfan Gwasanaethau Cwsmeriad/Customer Services Centre - 03000 65 3000 E-bost/E-mail: [email protected] Ewch i / Browse our Data Services webpage Gwefan/Website: www.cyfoethnaturiolcymru.gov.uk/www.naturalresourceswales.gov.uk Os hoffech i'n hymateb fod yn Gymraeg neu'n ddwyieithog, rhowch wybod i mi drwy roi clych o amgylch yr opsiwn priodol isod: If you would like our response to be in the Welsh language or bilingual, please let me know by circling the appropriate option below: Cymraeg/Welsh - Dwyieithog/Bilingual

Ein diben yw sicrhau bod adnoddau naturiol Cymru yn cael eu cynnal, eu gwella a’u defnyddio yn gynaliadwy, yn awr ac yn y dyfodol. Our purpose is to ensure that the natural resources of Wales are sustainably maintained, enhanced and used, now and in the future.

Fr o m : Haines, Natalie [mailto:[email protected]] Se n t : 19 July 2017 08:41 To: Data Distribution Su b j e ct : RE: ATI13209C Flood Product 4 Invoice Fitzalan High School, CF11 8XB

Thanks M i chel l e We were aware of this data set… but these only provide an estimate of levels at the coast/ estuary shoreline. We were expecting the Product 4 to include level, velocity, depth etc data for the site ….. most probably from the SFCA (similar to like the Tremorfa site?) Natalie

Fr o m : Data Distribution [mailto:[email protected]] Se n t : 18 July 2017 17:47 To: Haines, Natalie Su b j e ct : RE: ATI13209C Flood Product 4 Invoice Fitzalan High School, CF11 8XB

Dear Natalie,

Further to your email, please note that the tidal data is now available from the Welsh Government website Lle, on the page linked below: http://lle.gov.wales/catalogue/item/CoastalDesignExtremeSeaLevels/?lang=en

The data is in ESRI Shp format.

I trust this enables you to complete your assessments.

Yours sincerely,

6 Michelle

Fr o m : Haines, Natalie [mailto:[email protected]] Se n t : 18 July 2017 16:23 To: Data Distribution Cc: Williams, Clive R Su b j e ct : RE: ATI13209C Flood Product 4 Invoice Fitzalan High School, CF11 8XB

Dear Mi chel l e

Many thanks for the prompt reply with the Product 4 data.

I have reviewed the information today and it seems that Product 4 data issued only provides flooding data relating to fluvial sources (Rivers Taff and Ely).

NRW have previously confirmed (see attached) that the site as at risk from both fluvial and tidal flood sources. To complete the flood consequences assessment will also need the equivalent information for tidal sources.

Please can the tidal risk data also be provided

Thanks, Nat al i e

Natalie Haines (née Newton) IEng MICE Engineering Project Manager

D +44 (0)29 2046 7871 T +44 (0)29 2046 7800 F +44 (0)29 2047 1888 [email protected]

Mott MacDonald Fitzalan House Fitzalan Road Cardiff CF24 0EL United Kingdom

Website | Twitter | LinkedIn | Facebook | YouTube

7 Mott MacDonald Limited. Registered in England and Wales no. 1243967. Registered office: Mott MacDonald House, 8- 10 Sydenham Road, Croydon CR0 2EE, United Kingdom The information contained in this e-mail is intended only for the person or entity to which it is addressed and may contain confidential and/or privileged material. If you are not the intended recipient of this e-mail, the use of this information or any disclosure, copying or distribution is prohibited and may be unlawful. If you received this in error, please contact the sender and delete the material from any computer.

Fr o m : Data Distribution [mailto:[email protected]] Se n t : 17 July 2017 16:17 To: Haines, Natalie Cc: Williams, Clive R Su b j e ct : RE: ATI13209C Flood Product 4 Invoice Fitzalan High School, CF11 8XB

Dear Natalie,

Further to Clive’s payment earlier today, please now find attached your Product 4 for the above site, along with a copy of the FCA/FRA Standard Notice.

I trust this information is useful to you.

Yours sincerely,

Michelle

Fr o m : Data Distribution Se n t : 17 July 2017 10:57 To: '[email protected]' Cc: '[email protected]' Su b j e ct : ATI13209C Flood Product 4 Invoice Fitzalan High School, CF11 8XB

Dear Mrs Newton,

Thank you for your recent email requesting you wish to proceed with only Product 4 for 6 of the 7 sites.

1. Any historic flood information will be included as part of a product 4.

2. For Flood Risk Assessment advice, including whether surface water should be considered, Carl Llewellyn is the Development of Flood Risk officer for Cardiff and can be contacted at [email protected] or 0300 065 3092.

8 Therefore for a Product 4, this request is subject to a charge of £50.00 + VAT @ 20% (VAT registration number: GB 145 1537 25) Total charge = £60.00

In order to make this payment by credit / debit card please contact me on 03000 653577. Please note that for security reasons the cardholder will need to be present to authorise the transaction.

I look forward to hearing from you in due course.

Yours sincerely,

Michelle

Fr o m : Newton, Natalie [mailto:[email protected]] Se n t : 30 June 2017 16:50 To: Enquiries ; Dat a Dist ribut ion Cc: Price, Nicholas M ; Williams, Clive R Su b j e ct : ATI13209A Flood Product Enquiry for 2 sites in Cardiff Fitzalan School CF11 8XB & Pwll Coch School CF11 8DZ 300617

Dear Sir/ Madam

We have been appointed to prepare flood consequences assessments to support the potential redevelopment of five sites in Cardiff for “highly vulnerable” development (ref: TAN15). Location plans for the 5 sites, including nearest post codes and grid references are at t ached.

To inform the assessment please can you provide: - "Product 4" data including any modelled data for the site and local access roads - Information relating to the impact of climate change on flood risk in these locations - Any information on historic flooding events either at or adjacent to the site - Confirmation as to whether it would be expected that a surface water drainage assessment should be incorporated into the FCA.

Plus any further local flood risk assessment advice.

Please do not hesitate to contact me if you require further information to progress this request Regar d s, Nat al i e

Natalie Haines (née Newton)

9 IEng MICE Engineering Project Manager

D +44 (0)29 2046 7871 T +44 (0)29 2046 7800 F +44 (0)29 2047 1888 [email protected]

Mott MacDonald Fitzalan House Fitzalan Road Cardiff CF24 0EL United Kingdom

Website | Twitter | LinkedIn | Facebook | YouTube

10 Price, Nicholas M

From: Llewellyn, Carl Sent: 09 August 2017 12:02 To: Haines, Natalie Cc: Price, Nicholas M Subject: RE: Cardiff Schools FCAs

We have a couple of queries, and I am contacting you to seek advice. - tolerable conditions, as these are not provided in TAN15 A1.15 for schools, for our assessment we have adopted those given for residential (habitable rooms). Is this correct? Yes a maximum depth of 600mm is acceptable

- the Product 4 data provides average and maximum levels. For the purposes of identifying finished floor levels and tolerable conditions in extreme floods, please confirm it is appropriate to use the average levels not maximum levels. NRW adopt a precautionary approach therefore the maximum levels should be used unless there is justification to use lower values.

Regards

Eich Enw/ Carl Llewellyn Teitl swydd/ Dadansoddiad Risg Llifogydd / Flood Risk Analysis Cyfoeth Naturiol Cymru / Natural Resources Wales Ffôn/Tel: 03000 653092 E-bost/E-mail: [email protected]

The documents are available via the following link: http://gov.wales/topics/planning/policy/policyclarificationletters/2016/cl-03-16-climate-change- allowances-for-planning-purposes/?lang=en

From: Haines, Natalie [mailto:[email protected]] Sent: 08 August 2017 15:48 To: Llewellyn, Carl Cc: Price, Nicholas M Subject: Cardiff Schools FCAs

Good afternoon Carl,

As you are aware we have been preparing a number of preliminary FCA for the Cardiff Schools project.

1 - the Product 4 data provides average and maximum levels. For the purposes of identifying finished floor levels and tolerable conditions in extreme floods, please confirm it is appropriate to use the average levels not maximum levels.

Any advice greatly appreciated.

Regards, Natalie Ps. please also provide any reply to Nick Price (CC’ed) as I am away from my emails quite a bit between now and Monday.

Natalie Haines (née Newton) IEng MICE Engineering Project Manager

D +44 (0)29 2046 7871 T +44 (0)29 2046 7800 F +44 (0)29 2047 1888

[email protected]

Mott MacDonald Fitzalan House Fitzalan Road

Cardiff CF24 0EL United Kingdom

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2 Mott MacDonald | Leckwith Road Site 30 Flooding Consequences Assessment

B. Consultation with Cardiff Council (LLFA)

380206 | 009 | A | 8 September 2017 http://pims01/pims/llisapi.dll/properties/2119390873

Haines, Natalie

Fr o m : Newton, Natalie Sen t : 05 July 2017 17:27 To: '[email protected]' Cc: Price, Nicholas M; Probert, Caspar C Su b j ect : LLFA flood risk data request - Cardiff Schools Attachments: Location Plans - Cardiff Schools.pdf

Hi Dave

Sorry to contact you out of the blue (I did just try to call), however I understand that your colleagues in the council may have already been in touch, so hope the request contained within this email is not a complete surprise.

We have been appointed to assist Cardiff Council on the screening and appraisal of potential options for the redevelopment of a number of schools in the city.

Some of the schools are within (or partially within) DAM Zone C1, C2 or B, and we have been asked to prepare a preliminary Flood Consequences Assessment (FCA) to support the council’s project.

Location plans for the 7 sites are attached.

To inform the assessment please can you, as Lead Local Flood Authority, provide for the 7 sites: - Any hydraulic modelling information or anecdotal information of historic flooding events either at or adjacent to the sit es - Confirmation that this is the latest version of the Strategic Flood Consequences Assessment (SFCA) for the area https:/ / www.cardiff.gov.uk/ ENG/resident/ Planning/ Local-Development-Plan/ Evidence-Base/ Pages/Evidence-Base.aspx - Any plans to update the above SFCA in the future - Confirmation whether the sites lie within any Critical Drainage Areas (are areas where the council know drainage to be an issue) - Confirmation as to whether you would require an assessment of surface water drainage / SuDS to be incorporated into a FCA

Plus any further local flood risk assessment advice relevant to the site.

Hope you can assist. Please call if you need any further information. Thanks, Nat al i e

Natalie Haines (née Newton) IEng MICE Engineering Project Manager

D +44 (0)29 2046 7871 T +44 (0)29 2046 7800 F +44 (0)29 2047 1888 [email protected]

Mott MacDonald Fitzalan House Fitzalan Road

1 Cardiff CF24 0EL United Kingdom

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2 Mott MacDonald | Leckwith Road Site 31 Flooding Consequences Assessment

mottmac.com

380206 | 009 | A | 8 September 2017 http://pims01/pims/llisapi.dll/properties/2119390873