Policy information sourced from Three Rivers Development Management Policies DPD
DM8 Flood Risk And Water Resources
Development will only be permitted where it would not be subject to unacceptable risk of flooding; and would not unacceptably exacerbate risk of flooding elsewhere. Where practicable existing flood risks should be reduced.
New development will not be permitted in Flood Zone 3b, as defined by the SFRA. Redevelopment of existing built development in that Zone will only be permitted if the proposals are of a compatible use class and would not increase flood risk elsewhere.
A Flood Risk Assessment (FRA) will be required for development proposals of 1ha or more in Flood Risk 1 and for proposals for all new development in Flood Zones 2 and 3; or in an area in Flood Zone 1 where proposed development or a change of use to a more vulnerable class may be subject to other sources of flooding as identified in the SFRA. Land in Flood Zone 1 surrounded by areas of Zones 2 or 3 will be treated as if in the higher risk Zone and a FRA will be required to demonstrate that access and egress would be satisfactory and that the development would not be unacceptably vulnerable during a flood period.
Within sites at risk of flooding the most vulnerable parts of proposed development should be located in areas of lowest risk unless there are overriding reasons to prefer different locations.
Development at risk of flooding should be flood resilient and resistant, including safe access and escape routes where required; and it should be demonstrated that residual risks can be safely managed.
Floor levels of development in Flood Zones 2 and 3 should be situated above the 1% (1 in 100 years) plus climate change predicted maximum water levels, plus a minimum freeboard of 300mm.
Development in all areas should include Sustainable Drainage Systems to reduce surface water run off.
Where appropriate, developers will be required to show that any necessary flood protection and mitigation measures will not have unacceptable impacts on nature conservation, landscape character, recreation or other important matters.
Development should normally be set back from a main river (as defined by the Environment Agency) with a minimum 8m wide buffer zone and from any other watercourse with a minimum 5m wide bufferzone to prevent any significant impact from flooding.
Water resources
The Council will support development where:
- The quantity and quality of surface and groundwater resources are protected from aquatic pollution and where possible enhanced.
- There is an adequate and sustainable means of water supply and sufficient foul and surface water drainage
- Efficient use is made of water resources and account taken of climate change. This means incorporating all or some of the following measures as part of development:
- Rainwater harvesting techniques (for example providing waterbutts fitted to drainpipes and underground water storage as part of new development)
- Harvesting and recycling greywater (wastewater from baths, showers, washbasins, kitchen sinks)
- Using water efficient appliances (for showers, taps, washing machines, toilets etc.)
- Using water efficient landscaping and irrigation measures (for example by using drought tolerant plants)
- New development adjacent to water courses should seek to include river restoration and de-culverting.
For more information please see the Three Rivers Development Management Policies DPD