Sustainable Urban Drainage Systems Diederik Rousseau Tineke Hooijmans
Contents Presentation Water cycle links The issues facing stormwater management Conventional approach and drawbacks SUDS triangle and management train SUDS techniques Benefits and sustainability Examples: modelling and implementation
Water Cycle Percolation www.environment-agency.gov.uk
Links within the water cycle Stormwater Water quality Potential resource Sewer capacities Water treatment standards The Urban Water Cycle Water supply Potential resource Wastewater volume Wastewater SWITCH Training Kit by: R. Philip and B. Anton ICLEI Local Government s for Sustainability
The issues facing urban stormwater management Increased urbanisation Inadequately designed and maintained infrastructure Changing weather patterns due to climate change Fragmented management structures SWITCH Training Kit by: R. Philip and B. Anton ICLEI Local Government s for Sustainability
Links between stormwater management and other areas of the water sector Water supply Water treatment Wastewater management Water quality SWITCH Training Kit by: R. Philip and B. Anton ICLEI Local Government s for Sustainability
Links between stormwater management and other sectors of urban management Roads and transport Housing Solid waste Parks and gardens Land-use management SWITCH Training Kit by: R. Philip and B. Anton ICLEI Local Government s for Sustainability
The conventional approach Combined sewers Concrete drainage culverts, channels and pipes Disposal of stormwater directly into rivers, lakes and coastal waters Charles Humphrey North Carolina Cooperative Extension
Drawbacks of the conventional approach to stormwater management Increased downstream flood risk Erosion and sedimentation Overflows in combined sewer systems Pollution of receiving water bodies Waste of a valuable resource Charles Humphrey North Carolina Cooperative Extension
A more sustainable approach:the SUDS triangle reducing the impact of urban drainage on the environment SWITCH Training Kit by: R. Philip and B. Anton ICLEI Local Government s for Sustainability
A more sustainable approach: the concept Storm water attenuation and retention River restoration Combining water infrastructure with landscape design Embedding water management into existing urban and regional planning Incorporating water recycling facilities into urban architecture
SUDS management train http://www.ciria.org.uk
Objectives Encourage move away from end-of-pipe techniques Optimize management trains for different developments
Examples of SUDS techniques/systems Source control and prevention techniques Green roofs Permeable pavements Rainwater harvesting Infiltration trenches and basins Permeable conveyance systems Filter drains Swales Passive treatment systems Detention basins Retention ponds Wetlands
Source control and prevention techniques: Green roofs http://mypropertymentor.co.uk/2010/03/design-week-designingsustainable-urban-drainage/
Source control and prevention techniques: Permeable pavements
Source control and prevention techniques: Infiltration trenches and basins http://www.liv.ac.uk/science_eng_images
Source control and prevention techniques: Rainwater harvesting http://www.rwh.in/ http://www.pacificwater.org/pages.cfm/water-services/rainwater-harvesting/
Permeable conveyance systems: Filter drains and swales http://www.pavingexpert.com http://www.nrhtx.com/dept_pw_storm_terms.aspx
Passive treatment systems: Detention basins or dry ponds Harlow et al., 2000 Inlet
Passive treatment systems: Retention or wet ponds Harlow et al., 2000
Passive treatment systems: Wetlands Harlow et al., 2000
Benefits of sustainable urban drainage solutions Flood control Pollution control Protection against erosion Aquifer replenishment Alternative source of water Amenity value Climate change adaptation
Why the non-conventional approach is more sustainable Amenity value Social sustainability Reduced flood risk Protection and enhancement of natural habitats Reduced pressure on natural water supply sources Environmental sustainability Economic sustainability Reduced treatment and pumping costs Reduced flood risk
Example MUSIC Model for Urban Stormwater Improvement Conceptualisation (http://www.toolkit.net.au/music) Conventional Drainage Scenario - Pipes designed not to flood under the critical 1 in 30 year return period event - (Rapid) discharge to combined sewer - No attenuation Retrofit SuDS in Theory and Practice Virginia Stovin (2007)
MUSIC Model for Urban Stormwater Improvement Conceptualisation (Retrofit) SUDS Design Scenario Implements: Green roofs Porous carparks Swales Pond Retrofit SuDS in Theory and Practice Virginia Stovin (2007)
MUSIC Model for Urban Stormwater Improvement Conceptualisation Hybrid Option - Conventional piped drainage with pond (simpler retrofit) Retrofit SuDS in Theory and Practice Virginia Stovin (2007)
MUSIC Model for Urban Stormwater Improvement Conceptualisation Retrofit SuDS in Theory and Practice Virginia Stovin (2007)
MUSIC Model for Urban Stormwater Improvement Conceptualisation Retrofit SuDS in Theory and Practice Virginia Stovin (2007)
MUSIC Model for Urban Stormwater Improvement Conceptualisation
MUSIC Model for Urban Stormwater Improvement Conceptualisation) Retrofit SuDS in Theory and Practice Virginia Stovin (2007)
Implementation example: Lamb Drove - SUDS residential scheme UK Lamb Drove is a new residential development of 35 homes, 1 hectare site (in city of Cambourne) Demonstration project http://www.ciria.org.uk/suds/cs_lamb_drove.htm
SUDS used management train: water butts permeable paving a green roof swales detention and wetland basins a retention pond http://www.ciria.org.uk/suds/cs_lamb_drove.htm
Comparison study sites The study comprises of a study site (Lamb Drove) and a control site (Friar Way) with similar characteristics in terms of a new residential development area of a similar size, but does not include the SUDS measures as described above. http://www.ciria.org.uk/suds/cs_lamb_drove.htm
Comparison of Discharge at the Lamb Drove SUDS site and the Control Site http://www.ciria.org.uk/suds/cs_lamb_drove.htm
Comparison of hydrocarbon concentrations at the SUDS site and control site http://www.ciria.org.uk/suds/cs_lamb_drove.htm
Key findings The SUDS features act to attenuate an delay discharge of water from the site The SUDS treatment train is acting to improve water quality; this is illustrated through reductions in concentrations of a variety of pollutants and other indicators There are significantly higher concentrations of hydrocarbons at the control site compared to the SUDS site There appears to be some reduction in metals as water progresses through the SUDs system but the most significant result is the reduction in zinc Suspended solids are generally below expected levels There is also a benefit in relation to Phosphorus, Nitrogen, COD, BOD and Ammonia http://www.ciria.org.uk/suds/cs_lamb_drove.htm
Key findings SUDS features offer environmental benefits through a diverse range of habitats and this benefit will increase as the site develops There have been problems regarding implementation of the original maintenance regime. This has been resolved through a site visit with the contractor http://www.ciria.org.uk/suds/cs_lamb_drove.htm
Other Issues Maintenance - swales and detention basins: a monthly site visit to undertake grass cutting, litter picking and inlet/outlet inspections. The permeable paving: maintenance includes biannual suction sweeping. Stakeholder information In addition a site display board has also been erected on site Monitoring ongoing monitoring of the system in order to demonstrate the long term impact of SUDS on both the quantity and quality of water leaving the site as well as environmental and social implications http://www.ciria.org.uk/suds/cs_lamb_drove.htm