A DOs and DON’Ts GUIDE

for PLANNING and DESIGNING

Sustainable UrbanDrainage Systems (SUDS)

DO

N’T

For developers, landowners, planners,

consultants, architects and engineers

SUDS

Further informationPlease contact your local SEPA office for further informationor visit the following websites:

www.sepa.org.uk/wfd

www.ciria.org.uk/suds

1 ‘Sustainable Urban Drainage Systems – Design Manual for Scotland andNorthern Ireland’ (CIRIA Report C521) and its successor ‘The SUDSManual’ (CIRIA Report C697 - to be published).

2 ‘Sewers for Scotland 2nd Edition – a Policy, Designed ConstructionGuide for Developers in Scotland’ (WRC - to be published).

3 The Water Environment (Controlled Activities) (Scotland) Regulations2005 Schedule 3 ‘General Binding Rules’ (Activities 10 & 11) andassociated guidance.

DON’Ts

� DON’T use existing ponds, wetlands or ditches forSUDS treatment.

� DON’T use attenuation tanks for water quality treatment.

� DON’T install end-of-pipe filter drains/infiltrationtrenches, swales or soakaways for >5 houses, unlessadditional SUDS treatment is provided upstream.

� DON’T design filter drains/infiltration trenches with abypass at the inlet.

� DON’T insert inlet pipes at the base of filterdrains/infiltration trenches - insert at high level.

� DON’T use filter drains/infiltration trenches where thewater table is shallow

� DON’T incorporate gulley pots in permeable paved areas.

� DON’T allow construction phase run-off to enter SUDSunless it is intended that the SUDS will be replaced orrestored. Temporary treatment systems separate to theSUDS should normally be provided.

� DON’T use infiltration based SUDS for industrial estatedrainage unless a groundwater risk assessment (priorinvestigation) has been undertaken and shown to beacceptable.

� DON’T use infiltration based SUDS on contaminated land,unless the system is impermeably lined.

� DON’T drain run-off from ‘high risk areas’ to the surfacewater drainage system (e.g. oil, chemical and wastestorage areas, delivery and refuelling areas, industrialyards, wash areas etc).

Who is this leaflet for?This leaflet is aimed at anyone involved in the planning ordesign of SUDS schemes. This includes developers, landowners,planners, consultants, architects and engineers.

What is it for?This leaflet provides a quick checklist of DOs and DON’Ts toconsider when planning and designing SUDS. This leafletshould be read in conjunction with the main reference sourcesfor the design of SUDS1, 2 and is not intended to replace thesemore detailed documents.

What are SUDS?SUDS mimic natural systems for draining surface water andinclude porous surfaces, soakaways, infiltration trenches, filterdrains, filter strips, swales, detention basins and purpose builtponds and wetlands. As well as treating polluted surface waterrunoff, SUDS provide attenuation of surface water to reducethe impact of flow on watercourses. Well designed SUDS canmake a positive contribution to the amenity and wildlife valueof a site.

Legal RequirementsThe main legislation covering the regulation of surface waterdischarges is the Water Environment (Controlled Activities)(Scotland) Regulations 2005. Through SEPA’s implementationof these regulations, certain categories of surface waterdischarge automatically require an application for a licence.For example, housing developments >1,000 houses, > 1,000car park spaces, industrial estates and motorways.

All other discharges of surface water, as a minimum, require tocomply with the General Binding Rules (GBRs) for surfacewater discharges which specify a requirement to provide SUDSor equivalent (with an exemption for single dwellings anddischarges to coastal waters3). If in doubt as to whether or nota licence is required, contact your local SEPA office.

Inappropriately or wrongly designed SUDS found to be causingpollution, or pollution arising during the construction phase ofdevelopment, may result in SEPA taking enforcement actionincluding a requirement to carry out remedial work and/orreferral to the Procurator Fiscal for prosecution.DO

DOs General

� DO allow sufficient landtake for SUDS when planning thesite layout (typically 5-7% of the site area but can besignificantly less if source control techniques are used).

� DO use a surface water management train.

� DO use source control, even when regional facilitiesare provided

� DO minimise impermeable areas and encourage as muchinfiltration as possible (except for certain industrial estatedrainage and on contaminated land – see list of DON’Ts).

� DO avoid pipes where possible - use swales oropen ditches.

� DO attenuate run-off to pre-development values.

� DO produce a maintenance schedule and ensure that anominated person/body is clearly responsible.

� DO design SUDS for wildlife and amenity (e.g. byproviding ponds and wetlands).

� DO provide site operators/new householders with writteninformation on the SUDS system you have provided andhow it works.

DOs Specific

� DO use porous surfacing for driveways and parking areasor allow run-off to shed to adjacent land.

� DO use sheet flow to direct water into infiltrationtrenches, filter drains, filter strips and swales rather thangulleys and pipes.

� DO use slotted pipes for filter drains in preference toflexible perforated pipes.

� DO use unsealed disconnecting manholes with porousbase and walls where suitable.

� DO use water butts to attenuate roof drainage.

� DO allow access for maintenance (e.g. formowing swales).

� DO use silt traps upstream of SUDS where appropriate.

� DO prepare a method statement detailing the pollutionprevention measures to be used during the constructionphase of any development.

� DO ensure inlet and outlet structures are adequatelydesigned to prevent erosion within the SUDS.

� DO check for wrong connections during construction andon completion of the development.

SUDS