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Outline drainage design checklist

The following checklists should be completed by the applicant and submitted as part of the relevant planning application in order to demonstrate that the necessary information has been supplied to assess the suitability of the proposed sustainable drainage system, in line with Paragraphs 103 and 109 of the National Planning Policy Framework (NPPF).

Failure to provide any of the information requested below may result in the Lead Local Flood Authority (LLFA) making recommendation for refusal of the planning application on grounds of insufficient information.

1. Demonstrate an understanding of the natural drainage characteristics within and adjoining the site.

2. Provide an outline assessment of existing geology, ground conditions and permeability through desk-based research e.g. a review of geology maps and catchment information and site visit observations. Infiltration tests should be carried out at this stage wherever possible.

3. Prepare a Conceptual Drainage Plan to show the above together with:

  1. The proposed 'management train'
  2. Indicative location and type of source control
  3. Site controls with storage locations
  4. Conveyance and exceedence routes
  5. The destination of runoff.

4. Provide a Conceptual SuDS Design Statement describing:

  1. The SuDS Design Criteria applicable to the site
  2. Reasoning for inclusion of the selection of SuDS features
  3. Indicative runoff rate calculations and attenuation volumes for the lifetime of the development
  4. Integration with landscape design
  5. Any phasing plan for the development
  6. Management of health and safety risks
  7. Explanation of land use decision and how they impact drainage
  8. Proposed method of flow control
  9. Information regarding the proposed treatment stages to be applied to each element of the site
  10. Demonstration that surface water/groundwater entering the development from adjacent land has been taken into account.

For further advice about the information requested in this checklist please contact Essex County Council using the following email address or view our SuDS guide (PDF, 15mb).

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