Cwrt Sart Comprehensive School,

Level 1 Flood Consequence Assessment

February 2017

Neath Port Talbot County Borough Council The Quays Brunel Way Baglan Energy Park Neath SA11 2GG

JBA Project Manager Jack Southon JBA Consulting 35 Perrymount Road Haywards Heath West Sussex England RH16 3BW Revision History Revision Ref / Date Issued Amendments Issued to V1.0 / February 2017 Draft Report Jonathan Morris V2.0 / April 2017 N/A issued as Final Jonathan Morris

Contract This report describes work commissioned by Jonathan Morris, on behalf of County Borough Council, by an email dated 16th January 2017. Neath Port Talbot County Borough Council's representative for the contract was Jonathan Morris of Neath Port Talbot County Borough Council. Aaron Barber and Jack Southon of JBA Consulting carried out this work.

Prepared by ...... Aaron Barber BSc Technical Assistant

Reviewed by ...... Jack Southon BSc MSc FRGS MCIWEM C.WEM CSci CEnv Chartered Senior Analyst, Team Leader

Purpose This document has been prepared as a Final Report for Neath Port Talbot County Borough Council. JBA Consulting accepts no responsibility or liability for any use that is made of this document other than by the Client for the purposes for which it was originally commissioned and prepared. JBA Consulting has no liability regarding the use of this report except to Neath Port Talbot County Borough Council.

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Acknowledgements We would like to acknowledge and thank Jonathan Morris from Neath Port Talbot County Borough Council as well as Natural Resources for their provision of the relevant information required for this assessment. Copyright © Jeremy Benn Associates Limited 2017 Carbon Footprint A printed copy of the main text in this document will result in a carbon footprint of 99g if 100% post- consumer recycled paper is used and 126g if primary-source paper is used. These figures assume the report is printed in black and white on A4 paper and in duplex. JBA is aiming to reduce its per capita carbon emissions.

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Executive Summary Background JBA Consulting was commissioned by Jonathan Morris from Neath Port Talbot County Borough Council to prepare a Flood Consequence Assessment to support the redevelopment of the Cwrt Sart Comprehensive School site, Old Road, , Neath, SA11 2ET. This Flood Consequence Assessment provides information pertaining to the nature of flood risk as the site and follows the Technical Advice Note 15 with regards to development and flood risk. It also considers potential next steps appropriate for mitigation options available for the development. The site area is approximately 3.71 hectares, and currently hosts the existing Cwrt Sart Comprehensive School buildings, now disused. The site is now considered to be a site for the demolition of the existing buildings and the development of a new primary school, with associated playgrounds, playing fields, sports pitches, parking, ancillary buildings and soft landscaping. Flood risk Natural Resources Wales' Development Advice Map indicated that the site is partially within both flood zones B and C2, and therefore is at risk of flooding. Flood Zone B indicates areas previously known to have flooded through examination of sediment records, and Flood Zone C2 indicates areas of floodplain not benefitting from significant flood defences. The is the source of the fluvial and tidal flooding. Tidal flooding is modelled to provide risk to the site in a 1 in 200-year scenario. Updated modelling by JBA for NRW has recently been completed for the Neath area, and part of the model covers the Cwrt Sart site. Pre-application comments submitted by NRW recommends that the site levels are compared to the modelled tidal levels of the 0.5%AEP with climate change and 0.1%AEP scenarios. As the model only partially covers the site, tidal levels were extrapolated across the remainder of the site to determine potential flood risk for the remainder of the site. It is estimated that: • The 1 in 200-year plus climate change tidal event will generate a peak water level of 7.45mAOD • The 1 in 1000-year plus climate change tidal event will generate a peak water level of 7.53mAOD When compared to the current ground levels of the site (sourced from Natural Resource Wales' 1m LIDAR dataset), it is considered that: • The site is at risk from the 1 in 200-year plus climate change event, as well as the 1 in 1000- year plus climate change event. • Maximum flood depths could potentially reach 0.75m above current ground level in the area of the planned school buildings during the 1 in 200-year plus climate change event. The site is also at risk from surface water flooding, with a depression in the site allowing water to flow and pool. Recommendations TAN15 policy A1.14 states that a highly vulnerable development such as a school should be designed to be flood free during a 0.5% AEP tidal flood event. This condition is met with the current site plan for current day tidal levels. However A1.5 states that development should be flood free for the lifetime of the development. The site is found to be within the 0.5% AEP tidal flood event including climate change (assuming development lifetime of 100 years), based on the extrapolation of the updated modelling of the River Neath, therefore finished floor levels or ground raising above the projected flood level should be considered to account for the impacts of climate change. It is recommended that, at the detailed design stage, the existing Neath model is extended to include the entire site and surrounding properties, to confirm the results of the extrapolation performed for this FCA. The model can be run to include raised site levels, to confirm impacts on flooding and surface water on the site and nearby third party land, and to review flood velocities and inundation rates (A1.15). As the planned building is located within a depression in the landscape, it is recommended that landscaping is confirmed in line with predicted tidal flood levels, and modelling run to confirm the

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impacts of surface water no longer flowing into this area, and flowing off of the impermeable structures. A Surface Water Drainage Strategy is advised in this case, in conjunction with the FCA.

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Contents

Executive Summary ...... iii 1 Introduction ...... 1 1.1 Terms of Reference ...... 1 1.2 FCA Requirements ...... 1 2 Site Description ...... 2 2.1 Site description...... 2 2.2 Site Topography ...... 2 2.3 Site soils and geology ...... 3 2.4 Watercourses ...... 3 2.5 Drainage Network ...... 4 2.6 Development Proposal ...... 4 3 Planning Policy and Flood Risk ...... 5 3.1 Planning context...... 5 3.2 DAM Zone & Vulnerability Classification ...... 5 3.3 TAN-15 Flood Zones ...... 5 3.4 Policy and Guidance Review ...... 6 4 Flood risk assessment ...... 8 4.1 Historical flooding ...... 8 4.2 Existing fluvial flood risk data ...... 8 4.3 Surface water flood risk ...... 13 4.4 Risk of flooding from reservoirs ...... 13 5 Conclusions and recommendations ...... 15 Appendices ...... I A NRW - Pre-application comments ...... I B Site Plan ...... II

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List of Figures Figure 2-1: Filtered 1m LIDAR DTM from NRW...... 3 Figure 2-2: Proposed site plan...... 4 Figure 3-1: Extract from NRW's Development Advice Maps...... 5 Figure 4-1: Updated River Neath Model, produced by JBA for NRW...... 9 Figure 4-2: Updated River Neath Model, present day tidal scenarios...... 10 Figure 4-3: Extrapolated tidal extent and depth - 0.5%AEP+CC ...... 11 Figure 4-4: Extrapolated tidal extent and depth - 0.1%AEP+CC ...... 11 Figure 4-5: 0.1%AEP+CC tidal flood risk, extrapolated over the planned development .... 12 Figure 4-6: 0.5%AEP+CC tidal flood risk, extrapolated over the planned development .... 12 Figure 4-7: Updated Flood Map for Surface Water - NRW ...... 13 Figure 4-8: Risk of flooding from reservoirs - NRW ...... 14

List of Tables Table 2-1: Site Summary ...... 2 Table 3-1: TAN15 Flood Zones Applicable to Site Location ...... 5 Table 3-1: Development Category Applicable to Proposed Development ...... 6 Table 3-2: Flood Risk Vulnerability and Flood Zone 'Compatibility ...... 6

Abbreviations AEP ...... Annual Exceedance Probability BGS ...... British Geological Survey CC ...... Climate Change DAM ...... Development Advice Map FCA ...... Flood Consequence Assessment FRMP ...... Flood Risk Management Plan JBA ...... Jeremy Benn Associates LDP ...... Local Development Plan LIDAR ...... Light Detection and Ranging MUGA ...... Multi Use Games Area NPTCBC ...... Neath Port Talbot County Borough Council NRW ...... Natural Resources Wales SuDS ...... Sustainable Drainage Systems TAN15 ...... Technical Advice Note 15 uFMfSW ...... Updated Flood Map for Surface Water

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1 Introduction

1.1 Terms of Reference JBA Consulting were commissioned in January 2017 to prepare a Flood Consequence Assessment (FCA) in support of a planning application to redevelop the former Cwrt Sart Comprehensive School site into a new primary school. This Level 1 FCA has been prepared in accordance with Technical Advice Note 15: Development and Flood Risk (TAN15)1.

1.2 FCA Requirements This FCA follows Welsh Government guidance on development and flood risk set out in the Technical Advice Note 15: Development and Flood Risk2 (TAN15). Where appropriate the following aspects of flood risk will be addressed in all planning applications over its expected lifetime in flood risk areas: • The likely mechanisms of flooding • The likely source of flooding • The depths of flooding through the site • The speed of inundation of the site • The rate of rise of flood water through the site • Velocities of floodwater across the site • Overland flow routes • The effect of access and egress and infrastructure, for example public sewer outfalls, combine sewer overflows, surface water sewers and effluent discharge pipes from waste water treatment works • The impacts of the development in terms of flood risk on neighbouring properties and elsewhere on the flood plain

1 Welsh Assembly Government, Technical Advice Note 15: Development and Flood Risk, 2004 2 Welsh Assembly Government. Planning Policy Wales. Technical Advice Note 15: Development and Flood Risk. July 2004. Welsh Assembly Government. Cardiff.

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2 Site Description

2.1 Site description The proposal is for the development of a new primary school on the site of the former Cwrt Sart Comprehensive School, Old Road, Briton Ferry, Neath, SA11 2ET. The proposed floorplan is approximately 2,400m2 across a single ground floor. Table 2-1: Site Summary Site name Cwrt Sart Comprehensive School Site area 3.71ha (approx.) Existing land-use Disused school

Purpose of development New primary school OS NGR SS 74424 95456 Country Wales County Neath Port Talbot County Local Planning Authorities Neath Port Talbot County Borough Council Lead Local Flood Authority Neath Port Talbot County Borough Council

Contains OS data © Crown copyright and database right 2017

2.2 Site Topography Filtered 1m LIDAR data obtained from Natural Resources Wales (Figure 2-1) shows that the site gently slopes from the highest point (11.93mAOD) in the south-east to the lowest point (5.74mAOD)

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on the eastern edge of the boundary. A depression of around 2m is present on the existing playing field, just to the east of the northern cluster of buildings. To the south-east of this, another depression in the land leads away from the site towards the Bethesda Cwrt Sart church adjacent the site on the A474.

Figure 2-1: Filtered 1m LIDAR DTM from NRW.

Contains OS data © Crown copyright and database right 2017 Contains NRW data © Crown copyright and database right 2017

2.3 Site soils and geology The soil on site is described as slowly permeable seasonally wet acid loamy and clayey soil. This was determined from the Cranfield University Soilscape viewer3. The British Geological Survey (BGS) Geology of Britain viewer was consulted to identify the local geological conditions. The site is underlain by the Hughes Member, comprising of sandstone deposited 309 to 307 million years ago. Immediately south of the site, the Hughes Member includes interbedded mudstone and siltstone. Sandstones are generally permeable, meaning that water can permeate the surface, and can contain a locally significant aquifer. The local structural geology of the Neath area is complex, with faulting evident on the geological maps. Faults can also be a conduit for water to flow. The superficial deposits are identified as glacial till at the south-eastern extent of the site, and to the north west of the site, the superficial geology is Tidal Flat Deposits, comprised of clays, silts and sands.

2.4 Watercourses The River Neath flows to the west of the site, approximately 1.5km away. The Neath flows from North to South, past the site and into Swansea Bay, and throughout this reach of the river the Neath is Tidal.

3 Cranfield University Soilscape Viewer http://www.landis.org.uk/soilscapes Accessed 17/01/2017

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An ordinary watercourse drains the hills to the south-east of the site, and flows into a culvert 420m south-east (Grid Ref. SS 74862 95105) of the site boundary at Old Road. The exact course of this culvert is currently unknown but it appears to runs underneath the site to the culvert outflow 65m to the north-west of the site (Grid Ref. SS 74259 95520). The Neath Canal runs 550m to the north west of the site.

2.5 Drainage Network The site is currently surfaced with both permeable and impermeable surfaces. The existing building, roads, pavement and playgrounds are impermeable, with the grass playing fields being permeable.

2.6 Development Proposal Currently, the site is split across numerous buildings, with areas of impermeable playground, parking, road and paving, as well as permeable playing fields. The buildings and surrounding playgrounds are found in two separate blocks, one to the north-west of the site, and one to the south-east, with playing fields in the north-east and trees and grass on the sites south-western border. The development proposal is for the existing buildings to be demolished, and a new single story primary school to be constructed in the middle of the site, with the main entrance and car parking to the south-east, new rugby pitch to the north east, gardens in the south-west, and Multi Use Games Area (MUGA) to the north of the proposed building (Figure 2-2). Surrounding the proposed school building is a continuous playground and path. The proposed school has a floor plate of approximately 2400m2. Figure 2-2: Proposed site plan

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3 Planning Policy and Flood Risk

3.1 Planning context TAN-15 was introduced in 2004 by the Welsh Assembly Government. Its technical guidance related to development planning and flood risk using a sequential characterisation of risk based on the Welsh Government's Development and Flood Risk Advice Maps (DAM). The main study requirement is to identify the flood zones and vulnerability classification relevant to the proposed development, based on an assessment of current and future conditions.

3.2 DAM Zone & Vulnerability Classification Figure 3-1 shows that the proposed development site falls within zones A, B and C2 as designated by the Development Advice Map. The proposal for a new primary school development is classed as 'highly vulnerable development' by TAN-15. TAN-15 states that highly vulnerable development is not acceptable in Flood Zone C2. Figure 3-1: Extract from NRW's Development Advice Maps.

Contains NRW data © Crown copyright and database right 2017

3.3 TAN-15 Flood Zones The proposed development site is located partially within Flood Zones A, B and C2. Table 3-1 shows how these flood zones relate to a sequential planning response.

Table 3-1: TAN15 Flood Zones Applicable to Site Location Zone A Considered to be at little or Used to indicate that justification test is not no risk of fluvial or applicable and no need to consider flood risk tidal/coastal flooding further. Zone B Areas known to have been Used as part of a precautionary approach to flooded in the past evidenced indicate where site levels should be checked by 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. Zone C2 Areas of the floodplain Used to indicate that only less vulnerable

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without significant flood development should be considered subject to defence infrastructure. application of justification test, including acceptability of consequences. Emergency services and highly vulnerable development should not be considered.

Schools are classified by TAN-15 as 'highly vulnerable', as detailed in Table 3-2. Consequently, TAN-15 states that such development should not be considered within Flood Zone C2, as shown in Table 3-3. Table 3-1: Development Category Applicable to Proposed Development Highly Vulnerable Development • All residential premises (including hotels and caravan parks) • Public buildings (e.g. schools, libraries and leisure centres) • Especially vulnerable industrial development (e.g. power stations, chemical plants, incinerators) • Waste disposal sites

Table 3-2: Flood Risk Vulnerability and Flood Zone 'Compatibility Development Emergency Highly Vulnerable Less Vulnerable Category Services Development Development (Table 3-2) Flood Zone ✓ ✓ ✓ Zone A (Table Zone ✓* ✓* ✓* 3-1) B Zone Justification Test Justification Test Justification Test C1 Zone   Justification Test C2

✓ Development is appropriate  Development should not be permitted Notes for Table 3-3: The shaded boxes represent the relevant boxes for this development. *If site levels are greater than the flood levels used to define adjacent extreme flood outline.

3.4 Policy and Guidance Review

3.4.1 Local Development Plan The Local Development Plan (LDP) is a land use document which sets out how the County Borough will be developed over 15 years (2011-2026). The current LDP was adopted by Neath Port Talbot County Borough Council (NPTCBC) on 27th January 2016. No specific polices have been identified relating to expansion and construction of new schools in Neath Port Talbot. However, a scenario of development of housing, business and retail projects that there will be a growth of 7800 new residential units and 7000 people by 2026. The need for new infrastructure and community services such as schools is mentioned as a result of this projected growth.

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3.4.2 Neath Port Talbot CBC Flood Risk Management Plan NPTCBC published the Flood Risk Management Plan (FRMP) in 2015. The FRMP is designed to inform planning and decisions made by key stakeholders such as Natural Resources Wales, regional planning bodies, IDB's, and owners and public businesses. The FRMP notes that the sources of flooding to Neath Port Talbot are fluvial and tidal flooding, to low lying areas within valley and coastal reaches. Briton Ferry, the location of proposed development, is on low lying land near the tidally influenced Neath River, and therefore is at risk from tidal and fluvial flooding. The railway embankment running north-south through Briton Ferry blocks pre-existing drainage routes, and therefore during larger rainfall events where the surface water drainage is at capacity or blocked, flooding occurs. Surface water flooding is an issue in Briton Ferry, due to the lack of permeable area in the urban environment, and it is predicted that the existing drainage systems are insufficient during exceptional rainfall events, leading to flooding. Numerous assets have been identified in the FRMP relating to drainage and flood risk, including pumping stations, and the Ynysmaerdy Culvert System, which is believed to run underneath the proposed site.

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4 Flood risk assessment This study assesses the risk from different types of flooding to the proposed development and the risk of flooding elsewhere from the proposed development, as well as how these flood risks can be managed. The main types of flooding that may apply to the proposed development site are fluvial and tidal flooding from the River Neath, and surface water flooding (overland flows due to impermeable surfaces). The approach to assessing flood risk at the development site was informed by the requirements of TAN-15 in conjunction with the client and NRW requirements. To meet the above objective, a desk based study was used, utilising existing flood risk data and recent modelling work undertaken for NRW in Neath. The primary objectives of this FCA are to determine the following: • Whether the site is at significant risk from any form of flooding; • If the site is at risk of flooding, determine if safe access to and from the site will be maintained during an extreme flood event; and, • The impacts of the development on flood risk to other sites, with particular focus on the effects of surface water from the site.

4.1 Historical flooding An assessment of historical flooding at the proposed development site and local area has been undertaken. The TAN-15 DAM map (Figure 3-1) shows that the proposed development site has been partially flooded previously (Zone B). Internet searches also show reports of flooding over the past 10 years in the local area of Briton Ferry. This is attributed to surface water flooding, localised on low lying roads such as Regents Street West railway tunnel.

4.2 Existing fluvial flood risk data JBA Consulting has recently completed a 1D-2D modelling scheme of the River Neath for NRW, and the license to use the data was requested on the 18th January 2017. The 2D model extent reaches the north-west edge of the proposed development site, at which there is a HQ flow boundary (Figure 4-1). The modelling shows the extent of a 0.1% AEP (1000 year) fluvial flood event, the A474 road adjacent to the site in the west is flooded, but the flood extent stops at the beginning of the bank leading up the school site. Therefore, the site is not at risk during a 0.1% AEP fluvial flood event. The model includes tidal flood scenarios. During the current 0.5% AEP and 0.1% AEP events (one in 200-year and one in 1000-year respectively), the proposed buildings are at a low risk of flooding (Figure 4-2). During a 0.5% AEP event plus climate change (One in 200-year 2116 scenario), flooding extends to the edges of the 2D model extent, which occurs over the site. As the boundary is an outflow, water will have left the model via this boundary, and therefore flooded the immediate surrounding area as well. For this FCA, the flood extent has been extrapolated to continue throughout the rest of the site at the same tidal level.

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Figure 4-1: Updated River Neath Model, produced by JBA for NRW.

Contains OS data © Crown copyright and database right 2017 Contains NRW data © Crown copyright and database right 2017

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Figure 4-2: Updated River Neath Model, present day tidal scenarios.

Contains OS data © Crown copyright and database right 2017 Contains NRW data © Crown copyright and database right 2017 For the 0.5% AEP event plus climate change (100 year 2116) tidal scenario, the maximum recorded tidal height within the site was modelled at 7.476mAOD. For the 1 in 1000 year plus climate change tidal scenario, the maximum recorded tidal height on site was 7.546mAOD. Figures 4-2 and 4-3 shows an extrapolated flood extent from the JBA model, using the maximum tidal flood height across the site. This flood height is compared against the NRW 1m LIDAR DTM, to provide a worst-case scenario tidal flood. Predicted flood depths during the 200 and 1000 year plus climate change events do not exceed 1m across the site, except at the boundary with the A474 road, which sits at the bottom of a bank. The majority of the flooding on site is not predicted to exceed 0.5m in depth, except towards the site's western boundary, and at the dip in the existing playing fields. The proposed site is currently situated partially within the flood extents modelled, as the eastern wing sits within a topographic low (Figures 4-5 and 4-6). The planned playground and MUGA are also at risk of tidal flooding. TAN15 policy A1.14 states that a highly vulnerable development such as a school should be designed to be flood free during a 0.5% AEP tidal flood event. This condition is met with the current site plan for current day tidal levels. However A1.5 states that development should be flood free for the lifetime of the development. The site is found to be within the 0.5% AEP tidal flood event including climate change (assuming development lifetime of 100 years), based on the extrapolation of the updated modelling of the River Neath, therefore finished floor levels or ground raising above the projected flood level should be considered to account for the impacts of climate change.

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Figure 4-3: Extrapolated tidal extent and depth - 0.5%AEP+CC

Contains OS data © Crown copyright and database right 2017 Contains NRW data © Crown copyright and database right 2017 Figure 4-4: Extrapolated tidal extent and depth - 0.1%AEP+CC

Contains OS data © Crown copyright and database right 2017 Contains NRW data © Crown copyright and database right 2017

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Figure 4-5: 0.1%AEP+CC tidal flood risk, extrapolated over the planned development

Contains OS data © Crown copyright and database right 2017 Contains NRW data © Crown copyright and database right 2017 Figure 4-6: 0.5%AEP+CC tidal flood risk, extrapolated over the planned development

Contains OS data © Crown copyright and database right 2017 Contains NRW data © Crown copyright and database right 2017

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4.3 Surface water flood risk The redevelopment of a brownfield site has the potential to increase or decrease surface water runoff in both rate and volume. This is due to changes in the impermeable surface area, impacting infiltration into the ground. The proposed development on site is to demolish the existing school buildings, and build a new school in the middle of the site. The total impermeable surface area of the site is planned at approximately 1.542ha, with the existing site's impermeable surface area approximately 1.604ha. Therefore, the development should result in a reduction in impermeable surface area of 0.062ha. Surface water runoff arrangements for the proposed development should be agreed within a suitably detailed surface water drainage strategy for the site including details of Sustainable Drainage Systems (SuDS) that provide a reduction in overall surface water runoff at the site. The risk of flooding from surface water to the proposed development is very low to high, with the NRW's updated Flood Map for Surface Water (uFMfSW) showing the centre of the site to be at most risk, with water flowing into local topographic lows on the existing playing fields, and flowing to the south-west corner of the site, the lowest area, before flowing onto the A474 (Figure 4-7). Figure 4-7: Updated Flood Map for Surface Water - NRW

Contains OS data © Crown copyright and database right 2017 Contains NRW data © Crown copyright and database right 2017

4.4 Risk of flooding from reservoirs The risk of reservoir flooding to the site was determined from NRW's online Flood Risk Map. The map shows that there is no risk of flooding to the site from reservoirs (Figure 4-8).

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Figure 4-8: Risk of flooding from reservoirs - NRW

Site Location

Contains NRW data © Crown copyright and database right 2016

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5 Conclusions and recommendations

• JBA Consulting was commissioned by Neath Port Talbot County Borough Council to produce a Level 1 Flood Consequence Assessment (FCA) for the proposed redevelopment of a school at an existing disused school site at Cwrt Sart, Briton Ferry, Neath. This FCA follows Welsh Government guidance on development and flood risk as set out in the TAN- 15. • The development site currently comprised of a 3.71 hectare brownfield site, situated between Old Road and the A474, 1.5km inland from the tidal River Neath. • The proposed redevelopment is a 2,400m2 single storey primary school, with associated playgrounds, playing fields, multi-use sports pitches and parking. • The proposed site falls within Zones A, B and C2 as designated by The Welsh Government Development Advice Maps (DAM). According to TAN15, the proposed development should not be considered within Flood Zone C2 due to its classification as 'highly vulnerable'. • The proposed school building currently sits within Zones A and B, with zone C2 limited to the far western edge of the site, which is the lowest level of the site. • Data from NRW shows that the risk of fluvial flooding to the site is considered to be low, with models showing the greatest risk to site coming from tidally flooding of the River Neath. • JBA has recently developed an updated hydraulic model for the River Neath for NRW, and this model has been licensed and utilised for this FCA. • The model boundary occurs within the Cwrt Sart School site, therefore the maximum modelled tidal depths were extrapolated throughout the rest of the site. • Results from the extrapolated model show the site to be at risk during a 0.5% AEP plus climate change tidal flood event, with flood depths between 0m and 1m. • The NRW surface water flood risk map shows that the site is at risk from surface water flooding, due to the local topography causing pooling on site. The proposed site will provide a reduction in impermeable surface area from 1.604 to 1.542 hectares. • NRW has stated that they are concerned about the presence a culvert underneath the site (The FRMP identifies the Ynysmaerdy Culvert System in the area), and that no development should occur above this culvert. • Based on the currently available modelling and information regarding the site, we conclude that the development is at risk during a 0.5% AEP plus climate change tidal flood scenario. TAN15 policies A1.5 and A1.14 require development to be flood free throughout the buildings lifetime. Therefore, finished floor levels and site levels must be above the modelled flood level. • During the 0.1% AEP plus climate change tidal flood scenario, buildings and access roads should be not be inundated to flood depths exceeding 600mm, and velocities of water do not exceed 0.15m/s in properties and 0.3m/s on access roads. Maximum rate of rise of floodwater should not exceed 0.1m/hour. To validate these scenarios, it is recommended that the existing model is extended to include the whole site, and landscaping is updated to accurately represent the proposed site. • Using the extrapolated flood depths of the 0.5% AEP plus climate change and 0.1% AEP plus climate change tidal flood events, finished floor levels on site are recommended to be 7.48mAOD or above. • The site is currently as risk of surface water flooding, and whilst the impermeable area is expected to decrease, due to the location of the planned building being situated within the area at risk, sustainable drainage assessment is recommended to determine how surface water can be best managed on site, and how it can be managed off site. • It is recommended that, at the detailed design stage, the existing model is extended to include the entire site, which can provide more robust flood depth data, and provide water velocities and inundation rates, required by NRW to fulfil TAN15 requirements. It can also inform of impacts to third parties at neighbouring sites, ensuring development does not adversely affect others.

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Appendices A NRW - Pre-application comments

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Maes Newydd Llandarcy Neath Port Talbot SA10 6JQ

Ffon / Phone: 0300 065 3513 E-bost / E-mail:

[email protected] Jonathan Morris Neath Port Talbot County Borough Ein cyf / Our ref: CAS-27719-C7C7 Council The Quays Brunel Way Neath SA11 2GG Dyddiad / Date: 19 January 2017

Annwyl / Dear Mr Morris

PROPOSAL: NEW PRIMARY SCHOOL, TOGETHER WITH THE PROVISION OF GRASS SPORTS PITCHES, ACCESS, PARKING, LIGHTING AND LANDSCAPING SITE ADDRESS: FORMER CWRT SART COMPREHENSIVE SCHOOL, OLD ROAD, BRITON FERRY, NEATH, SA11 2ET

Thank you for consulting Cyfoeth Naturiol Cymru / Natural Resources Wales on the above pre-application, which we received on 23 December 2016.

We have significant concerns with the proposed development as submitted. We recommend that the following requirements relating to flood risk are taken into consideration with any subsequent planning application submission. We would object if the scheme does not meet these requirements.

Flood Risk The site is located partially within zone C2, as defined by the development advice maps referred to under TAN 15 Development and Flood Risk (July 2004). Our Flood Map information, which is updated on a quarterly basis, indicates the site to be within the 1 in 200 year and 1 in 1000 year probability flood event outlines. In accordance with TAN 15, the development category would be regarded as highly vulnerable development.

We advise that a flood consequence assessment (FCA) is undertaken for the site comparing ground levels to projected tide levels in the 1 in 200 year and 1 in 1000 year flood events including an allowance for climate change in both scenarios.

The criteria for the FCA, which should normally be undertaken by a suitably qualified person carrying an appropriate professional indemnity, is given under Section 7 and Appendix 1 of TAN 15.

European Protected Species - Bats We are in receipt of a report entitled, ‘Cwrt Sart School, Briton Ferry Bat & Owl www.cyfoethnaturiolcymru.gov.uk www.naturalresourceswales.gov.uk

Natural Resources Wales, Maes Newydd, Llandarcy, Neath Port Talbot, SA10 6JQ

Croesewir gohebiaeth yn y Gymraeg a'r Saesneg Correspondence welcomed in Welsh and English

Survey’ by Rob Colley Associates, dated May-June 2016 which has identified that bats were not using the buildings on the site. We therefore have no further comments to make with regard to this matter.

Contaminated Land We do not consider that the controlled waters at this site are not of highest environmental sensitivity, therefore we will not be providing detailed site-specific advice or comments with regards to land contamination issues for this site.

It is recommended that the requirements of Planning Policy Wales and the Guiding Principles for Land Contamination should be followed.

These comments are based on our assumption that gross contamination is not present at this location. If, during development, gross contamination is found to be present at the site and if advice is required please contact Natural Resources Wales.

Culverted Watercourse We note the presence of a culverted ordinary watercourse running through the site. We advise you consult the Local Authority’s Drainage Engineers who will be able to provide advice on this matter. We would however stress that no buildings should be constructed over the culvert.

Our comments above only relate specifically to matters that are included on our checklist Natural Resources Wales and Planning Consultations (March 2015) which is published on our website at this link (https://naturalresources.wales/planning-and- development/planning-and-development/?lang=en).

We have not considered potential effects on other matters and do not rule out the potential for the proposed development to affect other interests, including environmental interests of local importance. We advise that it is your responsibility to ensure that all other permits/consents relevant to the development are secured.

I hope the above comments are helpful, please do not hesitate to contact me if you have any queries.

Yn ddiffuant / Yours sincerely

Mr Ashley Bosomworth Ymgynghorydd Cynllunio Datblygu / Development Planning Advisor

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2017s5510 - FCA Cwrt Sart School (v1 April 2017).docx II

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