SUDS and Sustainability

1. SUDS and Sustainability Kate Heal, University of Edinburgh Neil McLean, SEPA Brian D’Arcy, SEPA

2. SUDS and Sustainability • Sustainability - Neil • Economic Issues • Social Issues • Environmental Issues • SUDS – Kate • Are SUDS Sustainable? • Pollutants and Ecology • Limits and Effects • Increasing the Sustainability of SUDS ?

3. Quote from the Brundtland report - 'development which meets the needs of the present without compromising the ability of future generations to meet their own needs'. The Sustainability Triangle Sustainable Development Environmental Economic Social

4. Economic Issues (i) • River restoration/flood control schemes may face major costs due to the legacy of contamination in stream sediments & hydrological impacts. • Can SUDS avoid the need for future flood control schemes if used at outset of major urbanisation projects in stream headwaters? • Can SUDS reduce costs by better management of the fate of persistent pollutants?

5. Economic Issues (ii) • There has been a progressive increase in sales of permeable surface systems in England – yet no regulatory driver: cost effectiveness drives uptake. • Formpave report that a permeable surface car park is about 15% cheaper than a conventionally drained one since no gullies or oil interceptor and fewer pipes • (P Hart)

6. Economic Issues (iii) • Can cost savings be achieved for SUDS technology ? • Motorway service areas M40 & M42 (R Bray Assoc.) • Schools Projects & Stroud College (R Bray Assoc.) • Savings are achievable when SUDS are an alternative, not an add-on • Challenge for public bodies is to allow developers to realise potential cost-savings

7. The SUDS Triangle • Water Quality • SEPA • Water Quantity • Local Authority • Habitat/Amenity • SNH Water Quality Water Quantity Habitat/Amenity

8. Social issues (i) • Abertay studies: questionnaires, door-to-door, focus groups (Apostalaki) • Community Engagement projects (e.g. DEX and SE Wedge) • Just look around the DEX site: ad hoc footpaths around every pond… people like water.

9. Tree with raised kerbed plot Stops water draining from pavement Keeping water out of tree’s root system Tripping hazard! Wet day in Perth with no permeable paving Puddles to be negotiated Social Issues (ii)

10. Environmental Issues • 16 fold increase in car/taxi mileage in last 50 years • 500km downgraded due to urban runoff • SEPA’s “Pressures & Impacts on Scotland’s Water Environment” Report & Consultation • Over 6,000 km of waterbodies “at, or probably at, significant risk” from diffuse pollution • Urban runoff • Bathing waters • SUDS can help ! Source; Campbell et al, 2004

11. Environmental Issues & SUDS • Protect aquatic environment using the SUDS treatment train • prevent deterioration • SUDS retrofits for river & bathing water quality and combined sewers • Restoration • SUDS as habitats where possible • Most important: need action to reduce traffic volume, & develop cleaner technology for construction & motor industries – • Are the drainage systems unsustainable? It’s the inputs of persistent pollutants that are not sustainable • SUDS – Lose the “S” for sustainable • UDS - Unsustainable Drained Substances!!

12. Are SUDS sustainable? • Maintenance requirement • Fate of pollutants • Redistribution of pollutants • Groundwater pollution • Disposal of SUDS sediments • Impoverished ecology • Exotic species, monoculture planting • SUDS failures

13. Estimated relative mass flow (%) of copper in different urban drainage systems for Sankt Gallen, Switzerland, (75,000 inhabitants) (after Boller, 1997)

14. Anthropogenic metal accumulation in top 5 cm soil over 8 years, Göteborg, Sweden (Lind & Karro, 1995) Scottish urban rivers sediment study (SEPA, 2003) • 23/26 sites: at least 1 metal exceeded lowest effect level • 4/26 sites: sediment classified as Special Waste

15. Abundance (No/sample) Halbeath Linburn Wetland Pond 7 Introductions with planting(Lancaster, 2003) 99 00 01 02 99 00 01 02 99 00 01 02 99 00 01 02

16. Limits to SUDS • SUDS designed for specific circumstances • e.g. 10-year, 60 minute storm • e.g. treat runoff from 90% annual storms • Poor design, construction and maintenance • Treatment facility ≠ pristine ecosystem • No one correct solution: in some situations conventional drainage techniques (or mixture) is most sustainable option • SUDS only one part of solution to urban drainage problems

17. Poor design, construction & maintenance • Blocked & broken inlets • Inlet to perforated pipe covered with sediment (Images: Wolfram Schluter, Ewan Associates) Inlet to trench Inlet Bypass

18. Groundwater inputs to Linburn Pond (Morgan, 2004) • Data from UWTC, University of Abertay: • Continuous rainfall for DEX catchment • Continuous outflow for Linburn Pond • Outflow > maximum possible inflow

20. Swale, Waterside Gardens Construction swale, Waterside Gardens Increasing the sustainability of SUDS • Surface water management train • Improved design at all scales: • Design with development • Design for maintenance • Design detailing • Community engagement from start • Multi-disciplinary approach

21. “SUDS: Sustainable urban drainage system: a sequence of management practices and control structures designed to drain surface water in a more sustainable fashion than some conventional techniques” (CIRIA C521, design manual for Scotland & Northern Ireland) Sustainable development is “a journey and not a destination” development is an opportunity…