Stewart, Helen

From: Mulla, Aisha

Sent: 23 October 2018 16:52

To: DEFA, Planning

Cc: 'Julia Shipley'

Subject: FW: 18/01044/B 22 Carrick Park - extension

Attachments: Sulby_Subset_4.pdf; FRA technical requirments for 1801044B.pdf

Dear Sir,

Please see our comments below for the above planning application.

18/01044/B - 22 Carrick Park

The above application proposes the construction of an extension to provide ancillary living accommodation within a fluvial flood zone as per the attached flood map. This map indicates the predicted extent of fluvial flooding for a 1 in 100 year return period plus climate change. The published flood maps have taken the formal flood defences in the area into account. Even with the defences in position the site is at risk of flooding during the 1 in 100-year + climate change design event.

Due to the size of the extension and the fact that the additional building footprint would remove potential flood storage and could obstruct flood flow along the floodplain, Manx Utilities request that a detailed Flood Risk Assessment (FRA) is carried out to support this planning application. To assist the applicant we have attached some guidance on what the technical requirements are for the FRA and this site. This assessment should be prepared by (or in consultation with) a competent flood risk management specialist. Some of the required information has already been provided in parts of the application and just needs to be consolidated into one report for our records. Point 7 to 9 are the key requirements that are missing from the application.

If the applicant has any questions on this they can contact us on [email protected]

Kind regards,

Aisha

Aisha Mulla Technical Drainage Officer

PO BOX 177 * DOUGLAS * ISLE OF MAN * IM99 1PS * BRITISH ISLES

Tel: +44 (1624) 693513 E-mail: [email protected]

Web: +44 (7624) 426874 Web: www.manxutilities.im

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The Flood Map indicates the extent of their flooding associated with a flood event having a 1 % chance of occurring in any year ( 1 in 100 year event) and the extent of coastal flooding for the extreme sea level having a 0.5 % chance of occurring in any year ( 1 in 200 year event). In both cases the potential effects of climate change on flood magnitudes are associated for (by assuming a 50 % increase in peak river flows, and taking into consideration the predicted degree of sea level rise based on a 21 / 2 time horizon). The Flood Map indicates where forced flood defences and flood alleviation schemes are in place, and this mapped volume of flooding reflect the influence of flood defences on flood risk. However, d.dircon situations may not completely remove the risk of flooding to extreme events. It should also be noted that defences can be breached at risk in extreme weather conditions, and coastal defences can be overhapped by large waves. These additional risk factors are not considered in the Flood Map. The information provided is not an at resolution appropriate for localised flood risk assessments and should not be assumed as definitive at the property levels. Individual properties may, therefore, not always be at the same risk of flooding as surrounding areas/properties. If you believe that a particular property has a different risk of flooding to that shown on the Flood Map and/ or if you have information you believe may not have taken into account when preparing the Flood Map please contact Marie Utilities. As and when additional relevant information becomes available to Marie Utilities, the Flood Map will be improved and updated. Marie Utilities reserve all intellectual property rights associated with the Flood Map. Marie Utilities believe that the Flood Map, and information contained therein, records with the information currently available to it, but no representations or warranties (express or implied) are given with regard to its accuracy. To the fullest extent permitted by law Marie Utilities will not accept liability for any losses resulting in connection with the Flood Map. Unauthorized reproduction infringes copyright and may lead to prosecution or civil proceedings. Mapping is based upon the hire of Man survey map with permission of the Department of Infrastructure. (c) Crown Copyright Department of Infrastructure, Isle of Man.

| | Technical Requirements | | --- | --- | | Development Proposal | | | 1 | Identify proposed development location, type, use, size, and vulnerability. Detail current / historical site use. | | Part A: Background and understanding the scale of flood risk | | | 2 | Identify all sources of potential flooding. Provide a synopsis of previous flood history and discussion with Manx Utilities. | | 3 | Provide descriptions and plans (at an appropriate scale) of any structures, which may influence flooding to the development. | | 4 | Qualitative assessment of flood sources and baseline flood risk to the existing development site and surrounding environment to determine potential flooding sources and pathways | | 5 | Quantitative assessment of flood sources and baseline flood risk to the existing development site and surrounding environment to determine flood risk zones. Manx Utilities have already carried out hydrological and hydraulic assessments of this area - map of flood risk zone provided. | | 6 | Provide details on existing flood defences and alleviation measures. Will development be located behind an existing or proposed flood defence structure? | | Part B: Assess the flood risk from all sources, its mitigation and impact on others | | | 7 | Provide plans showing the existing site topography. Provide plans showing the development layout, finished floor levels and ground levels | | 8 | Provide details and plans outlining the proposed flood protection measures. | | 9 | Assessment of the impact of the development on the surrounding environment. Hydrological and hydraulic assessments will be required. |