Skip to content

Drainage Design

Sanderson Associates have been working on many different types of Drainage and Water Engineering projects over several years. Some of the many types of projects that we have been appointed and continue to act on are as follows:-

Drainage Design and Assessment

Prepare preliminary drainage strategies for proposed developments, including, where appropriate:-

  • The assessment of the existing drainage infrastructure on a site
  • Calculation of existing storm water run-off from Greenfield and previously developed sites
  • The preliminary assessment of storm water storage requirements and design of flood compensation works
  • The preliminary design and use of sustainable drainage techniques

Detailed design of domestic and mains drainage networks for foul and storm water flow, including: –

  • Determining the foul and storm water flows generated by new developments and optimum points of outfall
  • Assessing the capacity and suitability of existing drainage systems to accommodate additional flows
  • Design of detailed drainage layouts including routes and longsections
  • Hydraulic analysis and simulation modelling of foul and storm water drainage systems using WinDES software
  • Design of storm water flow attenuation measures including on-line and off-line storage facilities and simulation modelling
  • Sustainable Urban Drainage Systems and techniques (In accordance with the Flood and Waters Management Act 2010)
  • Sewer Adoptions and requisitions
  • Preparation of detailed drainage schedules, plans and sections for the purpose of construction and obtaining technical approval for Building Regulations or for Adoption by means of Section 104 of the Water Industry Act 1991
Drainage Design

For the purpose of design and undertaking site assessments we utilise AutoCAD based 3D modelling software combined with the WINDES suite of hydraulic design and analysis programs to provide a full detailed design of drainage schemes for construction purposes.

Domestic drainage systems are designed to meet the requirements of the current Building Regulations and are also modelled to check capacity and ensure optimum design in terms of pipe depth and gradient. Main drainage systems are designed to meet the requirements of the Sewers For Adoption 7th Edition and modelling data prepared to demonstrate their performance in normal use and under severe flood conditions.

National Planning Policy and Sustainable Urban Drainage Systems (SuDs) Technical Standards

New planning guidance came into effect on the 6 April 2015 which dictates the planning system will lead the drive for the delivery of Sustainable Drainage Systems.

Key changes are that:

  • SuDS are to be provided in new developments of 10 dwellings or more, or the corresponding non-residential or mixed use development;
  • Lead Local Flood Authorities are made Statutory Consultees on planning applications for surface water management; and
  • Planning Authorities are required to ensure that adequate arrangements are in place for the future maintenance of SuDS for the lifetime of the development either by condition or obligations.

In March 2015, the Department for Environment, Food and Rural Affairs introduced the Non-statutory technical standards for sustainable drainage system document which is to be used in conjunction with the National Planning Policy Framework and the Planning Practice Guidance documents and contains a number of standards. New standards which may significantly change how a site is developed and should be considered carefully are as follows:

  • New discharge rates for Greenfield developments should not exceed the 1 in 100 year rainfall events and wherever practicable the volume of runoff for the 100 year 6 hour event should not exceed the equivalent Greenfield runoff volume; and
  • New discharge rates for previously developed sites should be close to the greenfield runoff rate for the 1 in 100 year event but never exceed the previous runoff rate for the existing site. The volume of discharge for the 100 year 6 hour event should be limited to as close to the equivalent Greenfield runoff volume as possible but should never exceed the volume for the site prior to redevelopment.

Further Information

We have put together a dedicated website which you can view at this website includes detailed technical information about Drainage Design, something the majority of people wouldn’t even think about forming part of the planning and development process, the Design and Adoption of Drainage, Sustainable Urban Drainage Systems (SUDS), Drainage Impact Assessments and all the Drainage Detailed Design Services provided by Sanderson Associates.

Help With Drainage Design

We have vast experience dealing with Drainage Design covering many different types of proposed developments for our clients, we would welcome the opportunity to provide you with a competitive fee proposal.

Please get in touch with us if we can assist you further.