Policy information sourced from Newham Local Plan 2018

SC3 - Flood Risk and Drainage

Proposals that address the following strategic principles, spatial strategy and design and technical criteria will be supported:

  • Strategic Principles:
    • Taking in to account all sources1, flood risk (the likelihood of flooding plus the severity of its impacts) will be reduced. Development will not increase flood risk to any location;
    • Development and decision making will be informed by the Strategic Flood Risk Assessment (SFRA) and best available data2;
    • Flood Risk Assessments will be provided in line with national requirements and should be prepared in accordance with SFRA and Environment Agency advice. Consultation and initial investigation should be commenced sufficiently early in the design and planning process so that all opportunities to reduce flood risk can be identified and maximised; and
    • There is a presumption against impermeable hard-standing on domestic gardens and public open space.
  • Spatial Strategy:
    • Development will be located in areas with the lowest risk of flooding, demonstrated via passing of the Sequential Test and, if necessary, Exceptions Test3. The sequential approach applies across the Borough and within sites, such that areas of lowest risk should be identified and prioritised according to vulnerability of proposed use; and
    • Development (including redevelopment of existing buildings and sites) will be set back 16m from tidal flood defences and 8m from river defences (see ‘Indicative TE2100 Flood Defence Buffering’ on the Policies Map); in instances where no formal defences are present, development will be set back 8m from the top of the river bank.
  • Design and technical criteria:
    • Proposals adjacent to flood defences must confirm, through liaison with the Environment Agency, that defence structures are in good condition and will provide protection for the lifetime of the development with improvements made where necessary; this includes ensuring that the provisions of TE2100 can be met;
    • Development in Flood Zone 2 or 3 should:
      • Create space for water;
      • Be designed and constructed to be flood resilient;
      • Locate vulnerable uses above ground floor level, whilst still delivering active, welcoming and functional street level design;
      • Ensure all basement locations provide internal access and egress via floors no less than 300mm above the 1% annual probability flood level + allowance for climate change, or above the 2100 tidal breach flood level where the site is within the Thames tidal breach flood extent;
      • Ensure all ‘more vulnerable’, ‘highly vulnerable’ and ‘essential infrastructure’ uses have finished floor levels no less than 300mm above the 1% annual probability flood level + allowance for climate change; and
      • Provide safe access/egress, such that occupants can reach Flood Zone 1 via public rights of way;
    • All development should enable separation of foul and surface flows and incorporate Sustainable Urban Drainage Systems (SUDS) that reduce surface water run-off. All Major development and any development falling within a Critical Drainage Area (CDA) should achieve Greenfield Run-off and be accompanied by a Surface Water Drainage Strategy that:
      • Clarifies before- and after-development run-off rates and addresses water quality impacts, ensuring run-off is clean and safe;
      • Follows the Drainage Hierarchy of the London Plan;
      • Maximises the use of SUDS in accordance with the SUDS hierarchy (see SC1);
      • Confirms the ownership, management and maintenance arrangements of any SUDS features;
      • Shows regard to the recommendations of Newham’s Surface Water Management Plan (SWMP) and Local Flood Risk Management Strategy (LFRMS);
      • Confirms, only where it can be demonstrated that site conditions prohibit the achievement of greenfield run-off, that a rate no higher than 3 times greenfield will be achieved; and
    • Where culverted watercourses are present, opportunities for de-culverting should be investigated. Where de-culverting is not possible within the realities of a site, contributions to de-culverting elsewhere in the Borough may be sought.

For more information please see the Local Plan 2018