Sustainable Drainage Systems (SuDS) are a collection of alternative drainage solutions to pipe networks for surface water discharge. They offer a variety of benefits not provided by a conventional pipe network such as amenity value, pollution treatment and promoting biodiversity.

The governing document for SuDS in the UK is CIRIA 753: The SuDS Manual. The use of SuDS is integral to Link Engineering’s sustainability policy and as such CIRIA 753 is regularly used by the engineers here at Link for the design of drainage networks.

This document provides advice on the design, construction and maintenance of 13 different SuDS features used for many types of developments, which are:

• Rainwater Harvesting: These systems collect, treat (if needed) and store runoff to provide a supply of water for domestic, commercial or industrial purposes (Chapter 11, CIRIA 753: The SuDS Manual).
• Green Roofs: These are areas of vegetation on building roofs that provide amenity and biodiversity, whilst also reducing surface water runoff (Chapter 12, CIRIA 753: The SuDS Manual).
• Infiltration Systems: These promote the infiltration of surface water into the surrounding ground if the ground conditions permit it. Example systems include soakaways, infiltration trenches and infiltration basins (Chapter 13, CIRIA 753: The SuDS Manual).
• Proprietary Treatment Systems: These are underground manufactured products such as vortex or oil separators that remove contaminants from runoff and therefore protect downstream SuDS features (Chapter 14, CIRIA 753: The SuDS Manual).
• Filter Strips: These are sloped strips of grass or vegetation that provide treatment of runoff from hardstanding areas and therefore protect downstream SuDS features (Chapter 15, CIRIA 753: The SuDS Manual).
• Filter Drains: These are stone trenches that provide attenuation and treatment of runoff from hardstanding areas. They can be designed for infiltration if the ground conditions permit it (Chapter 16, CIRIA 753: The SuDS Manual).
• Swales: These take the form of long vegetated open channels that convey, treat and attenuate surface water whilst offering biodiversity and amenity benefits (Chapter 17, CIRIA 753: The SuDS Manual).
• Bioretention Systems: These are landscaped areas underlain by engineered soils that offer amenity and biodiversity and provide treatment of runoff. They can be designed for infiltration depending on the ground conditions. A commonly specified form of bioretention systems is a Rain Garden. (Chapter 18, CIRIA 753: The SuDS Manual).
• Tree Pits: These improve the visual appeal, biodiversity and carbon footprint of a development and can be designed to provide treatment, reduction and infiltration of surface water (Chapter 19, CIRIA 753: The SuDS Manual).
• Pervious Pavements: These allow surface water to infiltrate into the pavement layers below, which is then either channelled into the pipe network or infiltrated into the ground if permitted. Pervious pavements are divided into two types. Porous Pavements allow infiltration across their whole surface (such as gravel) and Permeable Pavements consist of impervious units separated by gaps for surface water to pass through (such as block paving) (Chapter 20, CIRIA 753: The SuDS Manual).
• Attenuation Storage Tanks: These are constructed underneath car parking and roads and store high volumes of water to reduce runoff leaving the site. These usually comprise geocellular tanks or high diameter pipes (Chapter 21, CIRIA 753: The SuDS Manual).
• Detention Basins: These are landscaped or hardstanding depressions in the site that can be used recreationally during dry periods, but also offer storage of surface water and runoff rates during storm events (Chapter 22, CIRIA 753: The SuDS Manual).
• Ponds and Wetlands: These are landscaped depressions in the site with a permanent depth of water and aquatic vegetation. They provide attenuation of surface water, whilst providing amenity and biodiversity benefits (Chapter 23, CIRIA 753: The SuDS Manual).