The Planning System and Flood Risk Management - Offaly County ...

More documents

Recommendations

Info

66Planning Guidelines• The impact of flooding on a site including:- The likely rate at which flooding might occur (i.e. rapid onset orslow rise of flood water);- The speed of flow of flood water;- The order in which various parts of the location or site mightflood;- The likely duration of flood events;- The economic, social and environmental consequences of floodingon occupancy of the site.• Information on extent and depth of previous flood events or on floodpredictions;• An assessment of how safe access and egress can be provided for routineand emergency access under both frequent and extreme flood conditions;• An assessment of how the layout and form of development can be usedto reduce or minimise flood risk;• Proposals for surface-water management according to sustainabledrainage principles, with the aim of not increasing, and where practicable,reducing the rate of run-off from the site as a result of the development;• The likely impact of any displaced water on third parties caused byalterations to ground levels or raising flood embankments;• The potential impact on fluvial or coastal morphology and the likelylonger-term stability and sustainability of existing defences; and• The residual risks to the site after the construction of any necessarydefences and measures and the means of managing these risks. Thisshould include an assessment of whether the measures either designout the impacts of climate change or are adaptable to any increase inflood level.In addition to the requirements listed above, when completing a site-basedFRA as part of meeting the requirements of the Justification Test, an assessmentwill be required of on- and off-site opportunities for reducing flood riskoverall e.g. flood storage. This will include an appraisal of wider flood riskmanagement measures to which the development can contribute.An assessment of how surface water run-off will be managed should beaddressed in most FRAs. Drainage is a material consideration at the planningstage of a development and due consideration must be given to the impactof the proposed development on the catchment area. This includes anassessment of potential for both flood risk and pollution. Surface water runoffmay need to be assessed in all flood zones. The FRA should demonstratethat the surface-water drainage system takes account of SuDS principles, inaccordance with the design guidance referenced below. Where SuDS solutionsare not possible the FRA should identify the principles behind the chosenapproach and demonstrate that the method that gives the best environmentalprotection available at the site is adopted.
The scope of the FRA will depend on the type and scale of the developmentand the sensitivity of the area.67The basic requirements for the drainage aspects of FRA are as listed below:• An examination of the current and historical drainage patterns;• A concept drawing of the development proposal;• A brief summary of how the drainage design provides SuDS techniques;• Summary of SuDS to be incorporated;• The soil classification for the site;• Evidence of subsoil porosity tests including where possible at the locationof any intended infiltration device;• Calculations showing the pre- and post-development peak run-off flowrate for the critical rainfall event; and• Accompanying wastewater drainage proposals.Guidance on design standards for smaller drainage systems have traditionallybeen drawn from the An Foras Forbartha publication ‘Recommendations forSite Development Works for Housing Areas’, which was republished byDEHLG in 1998. This document is currently under review by the DEHLGwith the aim of making it more sustainable in respect of surface water drainagewhich would involve urging local authorities to adopt the Sustainable DrainageSystems (SuDS) approach. This document is available for download at thefollowing linkhttp://www.environ.ie/en/Publications/DevelopmentandHousing/Housing/FileDownLoad,2451,en.pdfA number of local authorities have also developed guidance documents toassist applicants in the preparation of their drainage design, including thedrainage impact assessment. The most comprehensive of these local authorityguidance documents is the ‘Greater Dublin Strategic Drainage Study: NewDevelopment Policy’http://www.dublincity.ie/WATERWASTEENVIRONMENT/WASTEWATER/DRAINAGE/GREATERDUBLINSTRATEGICDRAINAGESTUDY/Pages/NewDevelopmentPolicy.aspx.This is a comprehensive document and is complemented by the Greater DublinRegional Code of Practice for Drainage Works.http://www.dublincity.ie/WATERWASTEENVIRONMENT/WASTEWATER/Pages/GDSDSCodeofPractice.aspxPlanning Guidelines
Page 7:
At the site-specific level, develop
Page 10 and 11:
Planning Guidelines
Page 12 and 13:
2regard to the guidelines in the pe
Page 14 and 15:
4Planning GuidelinesReport of the F
Page 16 and 17:
6Chapter 2:Flooding - Key ConceptsP
Page 18 and 19:
82.5 Increase in flooding due to de
Page 20 and 21:
10Flood risk2.13 Understanding floo
Page 22 and 23:
122.21 In undertaking a flood risk
Page 24 and 25:
142.30 Increases in rainfall intens
Page 26 and 27: 16after periods of heavy rainfall.
Page 28 and 29: 18that also meet the objectives of
Page 30 and 31: 20more than 1 in 200). Development
Page 32 and 33: 22Government under Section 28 of th
Page 34 and 35: 24Planning GuidelinesDevelopment in
Page 36 and 37: 26Chapter 4:Flooding and Spatial Pl
Page 38 and 39: 28floodplain. Effective co-ordinati
Page 40 and 41: 30Planning GuidelinesFig. 4: Develo
Page 42 and 43: 32• Include zoning objectives to
Page 44 and 45: 34specific areas, ensuring that flo
Page 46 and 47: 36should use the flood risk informa
Page 48 and 49: 38planning authority to ensure that
Page 50 and 51: 40• these guidelines, and in part
Page 52 and 53: 425.22 Where development proposals
Page 54 and 55: 44Chapter 6:ConclusionPlanning Guid
Page 56 and 57: 46TermsDefinitionPlanning Guideline
Page 64 and 65: 54Appendix A - Screening for andCar
Page 66 and 67: 56Climate changeincreased intensity
Page 68 and 69: 58Strategic assessments provide the
Page 70 and 71: 60As part of a FRA, information on
Page 72 and 73: 62A successful FRA is characterized
Page 74 and 75: 64• Suggested policies for sustai
Page 78 and 79: 68An additional document on interpr
Page 80 and 81: 70Table A2: The Flood Risk Balance
Page 82 and 83: 72Appendix B - Addressing FloodRisk
Page 84 and 85: 74Figure B2 below illustrates how t
Page 86 and 87: 76drainage processes and removing p
Page 88 and 89: 78• Signing of floodplain areas s
Page 90 and 91: 80flood level. Care must be taken t
Page 92 and 93: 82Appendix C - Frequently AskedQues
Page 94 and 95: 84What does the SFRA not provide?Th
Page 96 and 97: 86pressure in the embankment and ge
Page 98: Printed on recycled paper containin
show all

The Planning System and Flood Risk Management - Offaly County ...

Create successful ePaper yourself

Delete template?

Save as template?