Policy information sourced from the Waltham Forest Local Plan

91 Managing Flood Risk

A. Flood risk will be managed by:

  1. Ensuring that all site allocations pass the Sequential Test, and where necessary the Exception Test, steering new development to areas with the lowest risk of flooding from all sources. ii. Requiring a site-specific Flood Risk Assessment (FRA) for all development proposals which are situated in Flood Zone 2 or 3, and for proposals which are situated in Flood Zone 1, which:
    1. Are 1 hectare or greater in extent;
    2. Involve a change of use to a more vulnerable class;(75) or
    3. Are within an area identified as having more critical drainage problems;
  2. Requiring site-specific FRAs to provide sufficient detail to assess the risk of flooding to, and arising from, development proposals from all sources, considering flood risk now and in the future.

B. As part of the site-specific FRA, development proposals must:

  1. Carry out a Sequential Test, unless:
    1. There is an adopted site allocation and the development proposal is consistent with the proposed use and there have been no significant changes to the known level of flood risk to the site; or
    2. The application is for development which is exempt from the Sequential Test(76) ;
  2. Carry out an Exception Test, where necessary, (77) to ensure the proposed development will provide wider sustainability benefits to the community that outweigh flood risk, and that it will be safe for its lifetime, without increasing flood risk elsewhere and where possible reduce flood risk overall; and
  3. Demonstrate a sequential approach to layout within the development site, in order to ensure that the most vulnerable uses within a development are located in the lowest risk parts of the site.

C. The site-specific FRA should be proportionate to the anticipated degree of flood risk and must demonstrate how flood risk will be managed and mitigated to ensure the development is safe from flooding and the impacts of climate change for its lifetime. This must include appropriate flood-resistant design and construction, incorporation of Sustainable Drainage Systems (SuDS), safe management of residual risk, and appropriate emergency planning.

D. Development proposals should incorporate SuDS unless there is clear evidence that this would be inappropriate. These must aim to achieve greenfield run-off rates and ensure that surface water run-off is managed as close to its source as possible.

E. Where greenfield run-off rates cannot be achieved, a payment in lieu will be secured to mitigate flood risk.

For more information please see the Waltham Forest Local Plan