Sanderson Associates Highways, Traffic, Transportation and Water Consulting Engineers

Flood Risk Assessment with Sanderson Associates

A Flood Risk Assessment is a requirement of all planning applications for major developments and developments proposed in areas at risk of flooding. A Flood Risk Assessment may also be requested for sites in a low risk flood zone where a risk from another source is identified i.e. surface water.

Sanderson Associates undertake site specific Flood Risk Assessments, for all types of developments, in all Flood Zones countrywide, in accordance with the requirements of the National Planning Policy Framework, TAN 15 (Wales) and the detailed guidelines set out in CIRIA Report 624.

Sanderson Associates have extensive experience of the new National Planning Policy Framework and the superseded PPS25 throughout the UK and can produce site specific assessments for all types of developments from single units through to major residential, office, retail and industrial developments.

The assessments undertaken are specific to each site and may be a screening report (Level 1) through to a detailed flood risk report including mitigation works (Level 3).

We also have experience of Flood Consequence Assessments TAN 15 (Wales) providing the same level of services as that of a National Planing Policy Framework assessment.

We aim to provide a high level of service in producing assessments in optimum time scales depending on the complexity of the assessment and consultation required.

In preparing Flood Risk Assessment Reports, Sanderson Associates consider initially: -

  • The flooding hazards which may cause a risk to the proposed development, or which might affect so as to increase flood risk elsewhere
  • Whether the proposed development would obstruct maintenance access to watercourses or flood defences or affect the integrity of a flood defence
  • Whether the development might lead to an increase in surface water run-off

If these preliminary investigations identify no risk of flooding or impact on existing drainage mechanisms, the resulting report will normally satisfy planning requirements. In cases where the risk of flooding is identified, further assessment would be undertaken to identify:-

  • Flooding mechanisms for each flood source by the preliminary assessment
  • Review the flood level and flow record data for each flood source identified by the preliminary assessment
  • The potential impacts of flooding including upstream and downstream of the development and on existing flood defences
  • Mitigation measures for consideration in the design of the development
  • If appropriate, the scope of any further work including flow modelling that might be necessary to conclude the Assessment

Sustainable Drainage Systems (SuDs)

In March 2015, the Department for Environment, Food and Rural Affairs introduced the Non-statutory technical standards for sustainable drainage systems document to address the National Planning Policy Frameworks commitment to sustainable drainage by expanding on its commitment to the introduction of sustainable drainage systems (SuDs) to manage and reduce surface water run off from developments.

The aspiration of this document is to firstly reduce and manage surface water from a site and secondly to ensure that sustainable drainage techniques such as drainage by infiltration are implemented where suitable.

This document should be read in conjunction with the National Planning Policy Framework and the Planning Practice Guidance documents.

Sanderson Associates prepare Sustainable Drainage Statements or a Drainage Impact Assessment, suitable for your planning application. This legislation requires any development site of 10 residential dwellings or more or the industrial/commercial equivalent to be assessed.

National Planning Policy Framework (NPPF)

The National Planning Policy Framework - [March 2012] may be viewed here in PDF format. NPPF replaced the previous guidelines set out in PPS 25.

Planning Practice Guidance (2014): Flood Risk and Coastal Change

A supplementary guidance document that superseded The National Planning Policy Technical Guidance (2012) has been published, this is a web browser based document. The section relating to Flood Risk and Coastal Change can be viewed here.

Tan 15 (Wales)

Technical Advice Note 15 - Development and Flood Risk - [July 2004] may be downloaded here. Note, Natural Resources Wales has taken over the functions previously carried out by the Environment Agency in Wales.

Request a Fee Proposal

If you wish to request a fee proposal then you may do so by calling us on 01924 844080 or, alternatively, completing our online fee proposal request form.