Longford County Development Plan 2021–2027

1. Page 481

   Cite this pagePDF p. 481 (opens the publisher’s copy in a new tab)
   16.4.23 Flooding DMS 16.205 Development Management Standards – Flooding The Council in assessing development proposals will consider the following criteria: Flood Zones and Appropriate Land Uses The table below indicates the types of land uses that are appropriate in each of the Flood Zones identified within the Plan area, in accordance with the 2009 Flood Risk Management Guidelines for Planning Authorities and Departmental Circular PL2/2014 (or any updated/ superseding legislation or policy guidance). Where developments/land uses are proposed that are considered inappropriate to the Flood Zone that may be identified in the future at project level following adoption of the Plan, then a Development Management Justification Test and site-specific Flood Risk Assessment will be required in accordance with The Planning System and Flood Risk Management Guidelines 2009 (and as updated). Flood Zones Overall probability Planning implications for land uses Highly Vulnerable Development Less Vulnerable Development Water Compatible Development Flood Zone A Highest Inappropriate – if proposed then Justification Test and detailed Flood Risk Assessment is required Inappropriate – if proposed then Justification Test and detailed Flood Risk Assessment is required Appropriate – screen for flood risk Flood zone B Moderate Inappropriate – if proposed then Justification Test and detailed Flood Risk Assessment is required Inappropriate due to climate change – if proposed then Justification Test and detailed Flood Risk Assessment is required Appropriate – screen for flood risk Flood Zone C Lowest Appropriate - detailed Flood Risk Assessment may be required Appropriate - detailed Flood Risk Assessment may be required Appropriate – screen for flood risk Notes (refer to Flood Risk Management Guidelines 2009 and ‘SFRA for the Longford County Development Plan 2021-2027’ for additional detail): ■ Highly Vulnerable Development – Houses, schools, hospitals, residential institutions, emergency services, essential infrastructure, etc. ■ Less Vulnerable Development – Economic uses (retail, leisure, warehousing, commercial, industrial, non-residential institutions, etc.), land and buildings used for agriculture or forestry, local transport infrastructure, etc. Water Compatible Development – Docks, marinas, wharves, water-based recreation and tourism (excluding sleeping accommodation), amenity open space, sports and recreation, flood control infrastructure, etc.County Development Plan 2021–2027 461

2. Page 482

   Cite this pagePDF p. 482 (opens the publisher’s copy in a new tab)
   DMS 16.206 Structural and Non-Structural Risk Management Measures in Flood Vulnerable Zones Applications for development in flood vulnerable zones shall provide details of structural and non-structural risk management measures to include, but not be limited to specifications of the following: a) Floor Levels In areas of limited flood depth, the specification of the threshold and floor levels of new structures shall be raised above expected flood levels to reduce the risk of flood losses to a building, by raising floor heights within the building structure using a suspended floor arrangement or raised internal concrete platforms. When designing an extension or modification to an existing building, an appropriate flood risk reduction measure shall be specified to ensure the threshold levels into the building are above the design flood level. However, care must also be taken to ensure access for all is provided in compliance with Part M of the Building Regulations. Where threshold levels cannot be raised to the street for streetscape, conservation or other reasons, the design shall specify a mixing of uses vertically in buildings - with less vulnerable uses located at ground floor level, along with other measures for dealing with residual flood risk. b) Internal Layout Internal layout of internal space shall be designed and specified to reduce the impact of flooding [for example, living accommodation, essential services, storage space for provisions and equipment shall be designed to be located above the predicted flood level]. In addition, designs and specifications shall ensure that, wherever reasonably practicable, the siting of living accommodation (particularly sleeping areas) shall be above flood level. With the exception of single storey extensions to existing properties, new single storey accommodation shall not be deemed appropriate where predicted flood levels are above design floor levels. In all cases, specifications for safe access, refuge and evacuation shall be incorporated into the design of the development. c) Flood-Resistant Construction Developments in flood vulnerable zones shall specify the use of flood-resistant construction aimed at preventing water from entering buildings- to mitigate the damage floodwater caused to buildings. Developments shall specify the use of flood resistant construction prepared using specialist technical input to the design and specification of the external building envelope – with measures to resist hydrostatic pressure (commonly referred to as “tanking”) specified for the outside of the building fabric. The design of the flood resistant construction shall specify the need to protect the main entry points for floodwater into buildings - including doors and windows (including gaps in sealant around frames), vents, air-bricks and gaps around conduits or pipes passing through external building fabric. The design of the flood resistant construction shall also specify the need to protect against flood water entry through sanitary appliances as a result of backflow through the drainage system.Longford County Council 462

3. Page 483

   Cite this pagePDF p. 483 (opens the publisher’s copy in a new tab)
   DMS 16.207 d) Flood-Resilient Construction Developments in flood vulnerable zones that are at risk of occasional inundation shall incorporate design and specification for flood resilient construction which accepts that floodwater will enter buildings and provides for this in the design and specification of internal building services and finishes. These measures limit damage caused by floodwater and allow relatively quick recovery. This can be achieved by specifying wall and floor materials such as ceramic tiling that can be cleaned and dried relatively easily, provided that the substrate materials (e.g., blockwork) are also resilient. Electrics, appliances and kitchen fittings shall also be specified to be raised above floor level, and one-way valves shall be incorporated into drainage pipes. e) Emergency Response Planning In addition to considering physical design issues for developments in flood vulnerable zones, the developer shall specify that the planning of new development also takes account of the need for effective emergency response planning for flood events in areas of new development. Applications for developments in flood vulnerable zones shall provide details that the following measures will be put in place and maintained: ■ Provision of flood warnings, evacuation plans and ensuring public awareness of flood risks to people where they live and work; ■ Coordination of responses and discussion with relevant emergency services i.e., Local Authorities, Fire and Rescue, Civil Defence and An Garda Siochána through the SFRA; and ■ Awareness of risks and evacuation procedures and the need for family flood plans. f) Access and Egress During Flood Events Applications for developments in flood vulnerable zones shall include details of arrangements for access and egress during flood events. Such details shall specify that: • flood escape routes have been kept to publicly accessible land; • such routes will have signage and other flood awareness measures in place, to inform local communities what to do in case of flooding; and this information will be provided in a welcome pack to new occupants. g) Further Information Further and more detailed guidance and advice can be found at http://www.flooding.ie and in the Building Regulations. Surface Water Drainage and Flooding Developments will be subject to the following requirements with regard to surface water drainage and flood prevention and management: a) Surface Water Drainage Drainage from paved surfaces may, after suitable treatment, be discharged to available watercourses or to adequate soakage areas on site. In any event, surface water shall not be permitted to flow on to the public road from any proposed development. Accesses and road frontage should be designed in such a manner as to deal with surface water and ensure that it does not impact on the public road. For rural houses, existing roadside drainage shall be maintained by the incorporation of a suitably sized drainage pipe. Each application shall be accompanied by design calculations or appropriate evidence to support the size of the pipe selected.County Development Plan 2021–2027 463

4. Page 484

   Cite this pagePDF p. 484 (opens the publisher’s copy in a new tab)
   Developments in flood vulnerable zones shall specify the use of flood-resistant construction aimed at preventing water from entering buildings - to mitigate the damage floodwater caused to buildings.Longford County Council 464

5. Page 485

   Cite this pagePDF p. 485 (opens the publisher’s copy in a new tab)
   b) Surface Water Run-Off Land uses shall not give rise to increases in the run-off characteristics above those that currently exist. c) Sustainable Drainage Systems The use of Sustainable Drainage Systems (SuDs) shall be encouraged in new developments to minimise the risk of flooding and contamination and to protect environmental and water resources. The Council will seek to ensure applicants incorporate sustainable drainage systems for significant developments in both urban and rural areas and will encourage them for other developments. SuDS is an approach that seeks to manage the water as close as possible to its origin by various engineering solutions that replicate natural drainage processes, before it enters the watercourse. The incorporation of SuDS techniques allows surface water to be either infiltrated or conveyed more slowly to water courses using porous surface treatments, ponds, swales, filter drains or other installations. SuDS should be designed to be cost-effective and require minimum maintenance. d) Flooding Development should not itself be subject to an inappropriate amount of flooding or exacerbate the risk of flooding at other locations. Development must so far as is reasonably practicable incorporate the maximum provision to reduce the rate and quantity of run-off. In particular, where appropriate: ■ Hard surface areas (car parks. etc.) should be constructed in permeable or semi-permeable materials; ■ On site storm water ponds to store and/or attenuate additional run-off from the development, should be provided. e) Floodplains Appropriately designed development that is not sensitive to the effects of flooding may be permissible in floodplains, provided it does not reduce the floodplain area or otherwise restrict flow across floodplains. Examples of such development might include park areas, sports pitches, certain types of industry warehousing, etc. designed to be flood resistant and/ or sensitive. Such developments should only be permitted provided it incorporates adequate measures to cope with the over-existent flood risk, for example, adequate drainage systems, safety measures, emergency response facilities and/or warning and response systems, and where it is considered that flooding would not result in significant hardship/ financial loss or cost. f) Watercourses For developments adjacent to all watercourses of a significant conveyance capacity or where it is necessary to maintain the ecological or environmental quality of the watercourse, any structures (including hard landscaping) must be set back from the edge of the watercourse to allow access for channel clearing/ maintenance/vegetation. Development consisting of the construction of embankments, wide bridge piers or similar structures will not normally be permitted in or across floodplains or river channels, as these structures restrict/obstruct flow and increase the risk of flooding to property and land upstream. It is considered necessary in exceptional cases to permit such structures; however, they should be designed to minimise and/or compensate for any potential negative effects.County Development Plan 2021–2027 465

6. Page 486

   Cite this pagePDF p. 486 (opens the publisher’s copy in a new tab)

   No text on this page — it is probably a drawing, a map, a photograph or a scanned page. See it in the PDF.

Source Longford County Council: Longford County Development Plan 2021–2027 (2021–2027) · Licence the publisher's termsText read from the publisher’s PDF; tables, maps and drawings do not survive as text, and page numbers are the PDF’s (its first page is 1). Check the original before relying on a passage.