From: SIRET, Peter on behalf of Flood Risk Management Sent: 05 March 2019 15:26 To: John Rowley Cc: Flood Risk Management Subject: RE: Draft policy Hi John, While the LLFA recognises the risk of surface water flooding posed by the Cotswold Escarpment (we have recently completed a flood alleviation scheme to the west of Cheltenham near the cemetery that tries to manage this risk), we feel the matters outlined in the below policy are dealt with by existing policies and therefore don’t believe it is required. For example, Flood Risk Assessments (FRA) assess the risk from all sources of flooding, including surface water. It is a requirement that an FRA is completed for sites that are in flood zone 2 or 3; in flood zone 1 and are more than 1ha; and are a change of use to a more vulnerable class that can be affected by sources of flooding other than fluvial (e.g. surface water). This risk should therefore be identified and addressed in FRAs. The Environment Agency have produced maps that highlight areas at risk of surface water flooding, which the LLFA would expect to see in a planning application that required an FRA. The “Non-statutory technical standards for sustainable drainage” says the site mustn’t flood, unless in an area of the site that is designed to, in a 1 in 30 year event and there should be no flooding to buildings in a 1 in 100 year rainfall event. This includes from overland flows coming onto the site from higher ground and this is something the LLFA looks for. Finally, the NPPF states that development should not increase flood risk elsewhere so if a development doesn’t capture overland flows coming onto the site then they need to manage it appropriately without increasing the risk to anyone else. If a development plans to capture and store this surface water then we would expect this to be included in their drainage strategy. The LLFA assess all major developments on these criteria so, although the escarpment can be considered a source of surface water flood risk, development on it is already covered by planning policy. I hope this makes sense. If there is anything you would like me to explain then please don’t hesitate to contact me. Many Thanks Peter Siret Sustainable Drainage Engineer Flood Risk Management (Strategic Infrastructure) Gloucestershire County Council 1st Floor, Block 5, Shire Hall, Westgate Street, Gloucester, GL1 2TG Tel: 01452 427493 Email: Peter.Siret@gloucestershire.gov.uk From: John.Rowley@cheltenham.gov.uk [mailto:John.Rowley@cheltenham.gov.uk] Sent: 01 March 2019 11:44 To: Flood Risk Management Subject: FW: Draft policy Dear Flood Risk Management team, During this week’s Cheltenham Plan hearing session a suggested policy was put forward by a member of the public. The Inspector has asked that Cheltenham Borough seek advice on the merits of the policy from the Environment Agency. However, as the policy relates to surface water flooding it is more appropriate to seek advice from yourselves. The draft policy can be seen below. In your opinion is the Cheltenham Plan legally unsound without this policy? This should be seen in the context of existing national policy as well as the JCS. We have a deadline to get back to the Inspector of the 8th March so could you please respond before that date? Please let me know if you have any questions. Kind regards John John Rowley Planning Policy Team Leader Cheltenham Borough Council Tel. 01242 264180 From: ADRIAN MEARS [mailto:adrian_mears@yahoo.co.uk] Sent: 27 February 2019 20:33 To: John Rowley Cc: Arlene Deane Subject: Draft policy Hi John This is my attempt at a draft policy as requested by the Inspector: 'Flood risk management is covered in section INF2 of the JCS and in JCS Policy INF2. The flood risk to Cheltenham is identified there as arising particularly from the River Chelt and from surface water flooding and overloading of the old drainage system, particularly during intense rainfall events. In areas close to the Cotswold Scarp there is a particularly strong risk of flash flooding from the very intense rainfall on the scarp, which can be of the order of 40mm in an hour. The scarp has catchments of various areas from a hectare up to tens of hectares. Depending on the catchment's area, landform, steepness and vegetation, the resulting run-off can become concentrated into strong flows even though the catchment may normally be dry. Major past storms have often been part of a double storm or sequence of storms such that the ground is almost fully saturated at the start of the storm. Policy: For any development located on or close to the Cotswold Scarp such that there is significant risk of flash flooding, the development application must include a careful and detailed assessment of any relevant catchment and of the likely run-off for a worst case storm and must clearly demonstrate that all units in the development together with the drainage system and any SUDs are suitably designed to cope with the impact. Also, the effect of the development on the course of the flow must be carefully examined and clearly documented in the application to show that the flow is not diverted in any way that could significantly increase the flood risk elsewhere. The conditions in JCS Policy INF2 also fully apply.' Best wishes Adrian This email (and any attachments) is an official Cheltenham Borough Council document. The information in this email and attachments is provided for the intended recipient. 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