Level 1 Strategic Flood Risk Assessment for Greater Manchester - Update Final Report March 2019 Manchester City Council Town Hall Albert Square Manchester M60 2LA JBA Project Manager Mike Williamson JBA Consulting Mersey Bank House Barbauld Street Warrington WA1 1WA Revision History Revision Ref / Date Amendments Issued to Issued V1.0 / March 2019 / GMCA comments Alex McDyre Draft V1.0 / March 2019 / Additional GMCA Alex McDyre Final comments Contract This report describes work commissioned by David Hodcroft, on behalf of Greater Manchester Combined Authority Planning and Housing Team, by email dated 28 August 2018. The lead representative for the contract was David Hodcroft. Mike Williamson of JBA Consulting carried out this work. Prepared by ...................................... Mike Williamson BSc MSc EADA FRGS CGeog Principal Flood Risk Analyst Reviewed by ..................................... Rachel Brisley BA Dip TRP MCD MBA AMBA Associate Director 2021s0741 GMCA Level 1 SFRA Update Final Report WCAG v1.0 i Purpose This document has been prepared as a Final Report for Greater Manchester Combined Authority. 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 Greater Manchester Combined Authority. 2021s0741 GMCA Level 1 SFRA Update Final Report WCAG v1.0 ii Acknowledgements JBA would like to thank all Greater Manchester Combined Authority, all Greater Manchester local authorities, Environment Agency, United Utilities and Natural England staff for their time and commitment to providing data and discussing the issues identified during the course of this study. Copyright © Jeremy Benn Associates Limited 2021 Carbon Footprint A printed copy of the main text in this document will result in a carbon footprint of 503g if 100% post-consumer recycled paper is used and 640g 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. 2021s0741 GMCA Level 1 SFRA Update Final Report WCAG v1.0 iii Executive Summary Greater Manchester Combined Authority (GMCA) commissioned JBA Consulting by email dated 28 August 2018 for the undertaking of an update to the Level 1 Strategic Flood Risk Assessment (SFRA) and Strategic Flood Risk Management Framework (SFRMF) to cover the ten Greater Manchester (GM) councils that make up GMCA. GMCA requires this updated Level 1 SFRA and SFRMF to support the Greater Manchester Spatial Framework (GMSF). This commission updates the original SFRA and SFRMF, completed in August 2018. It accounts for updates to the Greater Manchester Spatial Framework (GMSF) allocations and each of the ten GM district council's land supply sites for housing, office space and industrial / warehousing space. GMCA is acting on behalf of each of the ten councils; these are all designated Lead Local Flood Authorities (LLFA) as well as LPAs. In August 2014, the ten Local Planning Authorities (LPA) in GM agreed to prepare a joint Development Plan Document to set out the approach to housing and employment growth for the next 20 years. This is known as the GMSF (2019). This SFRA is required to: • initiate the sequential risk-based approach to the allocation of land for development and • identify whether application of the Exception Test is likely to be necessary using the most up-to-date information and guidance. This will help to inform and provide the evidence base for the GMSF and each individual council's local plan. The SFRA has been carried out in accordance with Government’s latest development planning guidance, namely: • the revised National Planning Policy Framework1 (NPPF) (updated February 2019) and 1 National Planning Policy Framework 2021s0741 GMCA Level 1 SFRA Update Final Report WCAG v1.0 iv • the flood risk and planning guidance the Flood Risk and Coastal Change Planning Practice Guidance2 (FRCC-PPG) (last updated March 2014, at the time of writing). The commission consists of three phases: 1. Existing and future flood risk screening of potential development sites under the following categories: a. GMSF allocations (2019); b. Baseline land supply (2018); c. Call for sites (2018). 2. Level 1 SFRA as per the requirements set out in the NPPF and FRCC- PPG; 3. Strategic Flood Risk Management Framework - GMCA requires a spatial framework to manage flood risk and development in GM. This will be used to set out the most significant areas of flood risk at the GMCA level. It will include for cross-boundary issues within and outside GMCA and recommend key priorities for intervention taking account of previous, existing and planned interventions delivered or to be delivered by all Risk Management Authorities (RMAs). The Framework will be informed by a review of relevant strategies, FRM governance and flood risk funding mechanisms. The SFRMF will be informed by this SFRA and in turn will inform the development of the GMSF. Phase’s 1 and 2 outcomes Development viability assessments for all potential sites are summarised through a number of strategic recommendations (see The outcomes of phase’s 1 and 2, based on existing risk, are summarised in Table 1-1 to Table 1-3. The effects of climate change on future development has also been assessed and is discussed in Sections 6.9, 7.2.2 and 7.3.3 of this report.). These are formulated from strategic assessments of flood risk and 2 Flood Risk and Coastal Change Planning Practice Guidance 2021s0741 GMCA Level 1 SFRA Update Final Report WCAG v1.0 v development vulnerability. The results of these assessments are included within Appendix B and C. The strategic recommendations broadly entail the following: • Strategic Recommendation A - consider withdrawal of site if development cannot take place outside of Flood Zone 3b; • Strategic Recommendation B - Exception Test required if site passes Sequential Test; • Strategic Recommendation C - consider site layout and design around the identified flood risk if site passes Sequential Test, as part of a detailed FRA or drainage strategy; • Strategic Recommendation D - site-specific FRA required; and • Strategic Recommendation E - site permitted on flood risk grounds due to little perceived risk, subject to consultation with the LPA / LLFA. The outcomes of phase’s 1 and 2, based on existing risk, are summarised in Table 1-1 to Table 1-3. The effects of climate change on future development has also been assessed and is discussed in Sections 6.9, 7.2.2 and 7.3.3 of this report. 2021s0741 GMCA Level 1 SFRA Update Final Report WCAG v1.0 vi Table 1-1: Summary of strategic recommendations for GM allocations (2019) Number of strategic recommendations applied Authority A B C D E Bolton 0 0 1 2 0 Bury* 0 0 3 3 0 Manchester 0 0 1 2 0 Oldham^ 0 2 5 10 0 Rochdale^* 1 1 5 6 0 Salford 1 0 0 3 0 Stockport 0 0 2 6 0 Tameside 0 0 1 3 0 Trafford 0 0 2 0 0 Wigan 0 0 4 1 0 GM 2 3 24 36 0 ^Two sites overlap between Oldham and Rochdale *Two sites overlap between Rochdale and Bury • Only two allocations are recommended for withdrawal if development cannot take place outside of FZ3b, based on the proportion of the site areas being within the functional floodplain. These allocations are in Rochdale and Salford. • Three allocations will have to be subject to and pass the Exception Test if the site boundaries cannot be altered to remove the high risk areas. Two of these sites are in Oldham and one is in Rochdale. • These five sites should be further investigated by the LPA and LLFA to ascertain developability. • 24 allocated sites require careful consideration of site design and layout with regards to avoiding or accommodating the flood risk. This should take place as part of a detailed site-specific FRA and drainage strategy used to inform the design and layout of the proposed site. 2021s0741 GMCA Level 1 SFRA Update Final Report WCAG v1.0 vii Table 1-2: Summary of strategic recommendations to baseline land supply (2018) sites Number of strategic recommendations applied Authority A B C D E Bolton 2 9 44 215 131 Bury 3 5 29 84 83 Manchester 3 9 53 281 272 Oldham 1 4 62 225 154 Rochdale 7 18 43 141 110 Salford 0 17 36 156 93 Stockport 2 5 31 197 176 Tameside 3 7 29 134 81 Trafford 1 4 23 211 105 Wigan 5 13 50 196 156 GM 27 91 400 1840 1361 • The majority of the baseline land supply sites, in Table 7-7, will require site-specific FRAs as a minimum (Strategic Recommendation D). • Many sites are also at very low risk and may not require any further assessment of flood risk (Strategic Recommendation E), though this is at the discretion of the LPA. • 27 land supply sites are recommended for withdrawal if the functional floodplain cannot be avoided, the majority being in Rochdale followed by Wigan. No land supply sites in Salford are recommended for withdrawal. • 91 sites will require the undertaking and passing of the Exception Test if development is to be permitted. Most of these sites are in Rochdale, Salford and Wigan. 2021s0741 GMCA Level 1 SFRA Update Final Report WCAG v1.0 viii Table 1-3: Summary of strategic recommendations for call for sites (2018) sites Number of strategic recommendations applied Authority A B C D E Bolton 2 1 32 90 4 Bury 4 1 32 92 2 Manchester 2 2 13 24 11 Oldham 1 8 45 83 11 Rochdale 11 4 38 79 4 Salford 1 4 18 30 1 Stockport 6 3 53 208 27 Tameside 4 1 22 82 5 Trafford 6 2 21 41 2 Wigan 10 2 32 83 4 GM 47 28 306 812 71 Included