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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.

The Royal Borough of Kensington & Chelsea SuDS D & E Guide © 2018 McCloy Consulting & Robert Bray Associates