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Outline Design  8.0   Design and Planning Stage 2 –


                            Outline Design





           Outline Design stage is an opportunity for the SuDS designer to develop the
           Concept Design to meet the requirements of the LPA and LLFA.


           Outline Design bridges the gap between Concept Design and Detailed Design
           and may require additional information to ensure that all aspects of the design

           are fully considered.




           8.1  Outline Design for                                   ■  A simple assessment of risk using the

           planning                                                  ‘treatment stage’ approach is acceptable
                                                                     on low and medium risk development. If
           The approach to Outline Design can be                     the risk screening (SuDS Manual p571)
           flexible to cater for different development               demonstrates that the ‘simple index
           scenarios.                                                approach’ is appropriate, then the
                                                                     ‘treatment stage’ is acceptable.
              ■  Where a large or complicated

  57           development is proposed the LPA would                 ■  All sites should demonstrate source
                                                                     control to remove silt, heavy metals and
               expect a pre-application discussion, based
               on the Concept Design, with                           hydrocarbon pollution at the beginning of
               recommendations incorporated into                     the management train.
               Outline Design confirming agreed                      ■  Unless permeable pavement is used to
               changes.
                                                                     collect runoff, where the pavement
              ■  For smaller and simpler developments                provides high water quality treatment,
               Concept and Outline design may be                     there will usually be a second feature to
               combined but the same design process                  manage additional volumes and provide
               must be demonstrated.                                 additional treatment.

              ■  On speculative submissions, where full
               access to the site is not possible, a
               detailed desktop survey of the site must
               be presented with flow route analysis to                                                     Facing:
               demonstrate runoff can be managed                    The outline design has developed the concept
               effectively on site and discharged to an                proposals to demonstrate how the scheme
                                                                        works and what it will look like when built.
               acceptable outlet.                                        Extract from Outline Design for Holyoaks
                                                                                   school, Robert Bray Associates.


           Luton Borough Council SuDS D & E Guide                                                              © 2018 McCloy Consulting & Robert Bray Associates
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