The Principles of SUDs

SUDS or Sustainable Urban Drainage Systems are a sequence of water management practices and/or facilities designed to drain surface water in a manner that will duplicate the natural water cycle and can be physical structures built to receive surface water runoff. They are located as close as possible to where the rainwater falls and provide the options of infiltration and attenuation. Additionally they treat surface water using the natural processes of sedimentation, filtration, absorption and biological degradation.

Research shows that typically up to 80% of sediment, 60% of phosphorous and 80% of nitrogen can be removed from stormwater through porous paving, together with substantial levels of heavy metals and hydrocarbons. This natural treatment provides the ideal opportunity for rainwater conservation and re-use for a variety of non-potable applications e.g. toilet/urinal flushing, irrigation, laundry, process water, vehicle washing, refrigeration, coolant use, etc. via rainwater harvesting. It also creates a cleaner output to the sewer or recharging of the groundwater where rainwater harvesting isn’t used. The Stormwater attenuation and infiltration units (StormMaster) provide bulk storage of stormwater so it can be dealt with efficiently and environmentally.

Such source control principles and techniques, also called Best Management Practices (BMPs) are already forming part of planning controls in some areas and will become increasingly incorporated within new development projects.

Current Guidance / Legislation on SUDs

• PPS 25 – Development and Flood Risk (Issued March 2010)
• Future Water – Government water strategy for England
• Code for Sustainable Homes
• CIRIA C697 – The SUDs Manual – Best Practice Guidance
• CIRIA C698 - Site handbook for the construction of SUDS
• Flood and Water Management Act 2010 – Management of flood risk by DEFRA
• Surface Water Management Plan – March 2010 giving guidance to Local Authorities
• National Standards for Sustainable Drainage - EA, LA’s & House Builders working together
• Pollution Prevention Guideline No.3 – Controlling pollution at its source
• Local Agenda 21 – Sustainable Development
• Water Framework Directive – Adopted into UK law

The four basic principles of SUDs

• Don’t hard pave surfaces unnecessarily - Porous Paving
• Soakaway where possible or attenuate if necessary - Stormwater Management
• Re- use if possible – Rainwater Harvesting

Use of the SuDs techniques above help to Improve water quality