Appeal by Lloyds Bank PLC

Transcription

1 Appeal by Lloyds Bank PLC Network Rail (Werrington Grade Separation) Order Transport and Works Act Town and Country Planning Act 1990 Land and buildings at Stirling Way, Peterborough Summary Proof of Evidence of Paul Jenkin BEng(Hons), MSc, CEng, C.WEM FCIWEM Peter Brett Associates LLP On behalf of Lloyds Bank PLC Project Ref: 4007/4002/001 Final Date: October 2017 Office Address: Waterloo House, Victoria Square, Birmingham B2 5TB T: +44 (0) E:

2 Document Control Sheet Project Name: Project Ref: Report Title: Summary Proof of Evidence Flood Risk Doc Ref: 4007/4002 Date: October 2017 Name Position Signature Date Prepared by: Paul Jenkin Partner October 2017 For and on behalf of Peter Brett Associates LLP ii

3 Contents Summary... 2 Credentials... 2 Contents... 2 Background to Flooding Issues... 2 Flood Risk Assessment & Hydraulic Modelling... 3 Surface Water Drainage... 3

4 Summary Credentials The summary Proof of Evidence is provided by Paul Jenkin who is a Partner at Peter Brett Associates and has overall responsibility for flood risk within the Practice. I am a Chartered Engineer with over 20 years' experience in the assessment of flood risk. I have worked on various frameworks with the Environment Agency as well as a number of Local Authorities. I have also prepared over a thousand FRA's for developments of various sizes across England, Wales and Scotland. Contents My evidence considers the Flood Risk Assessment (FRA) and hydraulic modelling that was undertaken by Jacobs in support of the development proposals. I outline the background to the flooding issue, the extent of work that was undertaken and describe the process that is required during detailed design to ensure that adequate reviews and approvals are undertaken. Background to Flooding Issues The Lloyds Bank Data Centre at Stirling Way, Peterborough is located in the vicinity of a complex network of water courses. These are crossed by various pieces of infrastructure including the railway line The site is protected from flooding by a perimeter flood defence and is also served by a surface water drainage system designed to reduce the risk of surface water flooding The proposals for the new rail alignment made by Network Rail will alter the capacity and alignment of the watercourses and could potentially increase flood risk to the Data Centre. To assess the environmental impacts, including flood risk, an Environmental Impact Assessment has been prepared (Arup, 2016) and this is supported by a Flood Risk Assessment (FRA) (prepared in October 2016) As a consultee to the planning process the Environment Agency agree that the principles set out in the FRA, supported by the modelling report, meet the requirements of the National Planning Policy Framework (NPPF) Whilst the proposals have been shown to be acceptable in principle it is vital that the detailed scheme is advanced in accordance with these principles and an appropriate condition is required to ensure that adequate review and approval is undertaken A planning condition would require submission of a detailed drainage scheme for sign off by the Lead Local Flood Authority (LLFA) in consultation with the Environment Agency in the process of it being discharged by Peterborough City Council In addition to any planning consent, a Flood Risk Activity Permit will be required for any works to the watercourses. These consents would be provided by the Environment Agency for Main Rivers and the LLFA for other watercourses To ensure that the planning consent takes these requirements into account a planning condition should be added which makes it clear that the works to the watercourses are undertaken in accordance with the principles set down within the FRA and associated designs and also that a Flood Risk Activity Permit is secured prior to any works commencing.

5 Under the Environment Agency protective provisions Network Rail would submit designs affecting main rivers to them for approval. At the same time Peterborough City Council would have sight of those designs and also designs affecting any non-main river designation for approval. Network Rail would liaise with the designer who would, generally, then submit the designs to the relevant technical expert in the Environment Agency and Peterborough City Council Due to the sensitivity of the Data Centre the Bank need to have the opportunity to review the final proposals which would be brought forward to discharge the planning condition. Flood Risk Assessment & Hydraulic Modelling PBA has reviewed the work undertaken by Jacobs for Network Rail. These reviews highlight a number of queries regarding the hydraulic modelling which, if not addressed or clarified, could lead to the model underestimating the impacts on flood risk and potentially leading to an increase in flood risk to the Data Centre From our discussions with the EA they have confirmed that in their view the proposals would not result in increased flood risk which adds to the overall confidence in the modelling At the time of writing this proof the responses received from Jacobs and the Environment Agency suggest that all but a few of the issues raised have either been resolved or clarification has addressed the comments from PBA The EA responded to each of our raised comments/concerns (in correspondence dated 19 th September 2017) with regards to the modelling work completed and confirmed that the hydrological and hydraulic modelling assessment was adequate following their review of the model There are a number of areas where further work is required but these are unlikely to have a material effect on the overall conclusions of the FRA and should be addressed as a matter of detailed design supported by the appropriate planning conditions Since the proposals do not increase the level of flood risk or reduce the standard of protection to the Data Centre there is no requirement for any works to be undertaken on site to mitigate the impacts of flood risk The two outstanding issues that can be addressed at detailed design are: Inconsistencies in the catchment area quoted in the model report. These areas have been used to derive the flow estimates within the watercourses. The EA agree these inconsistencies have been missed by JE and further clarification is required from JE, on behalf of Network Rail. EA agree that inclusion of the existing flood defence wall (see Appendix B) surrounding the Data Centre within the hydraulic model is desirable. Based on the original design parameters, this wall provides a 1 in 1,000 year standard of protection to the data centre. Since the FRA confirms that there will be no increase in flood levels as a result of the Network Rail proposals then this standard of defence should remain unchanged and no works would be required on the site of the data centre to mitigate flood risk. Surface Water Drainage The surface water drainage system is a gravity based system (with two independent drainage networks) with non-return valves where the pipes cross the flood walls and a pumped back up in the event of surcharge. This seems to be a robust system and should be resilient to flood events on the receiving watercourses.

6 It is therefore likely that the Data Centre would be at low risk of surface water flooding. It is also unlikely that the NR proposals would give rise to any increase in risk. Conclusion In addition to the process of EA approval, pursuant to the terms of the Draft Order, a planning condition should require detailed flood design and works to be submitted to Peterborough City Council, in order that LBG would have the ability to view and comment on.