Stormwater harvesting in urban environments Overview of engineering practice

1. Stormwater harvesting in urban environments Overview of engineering practice Results through Experience

2. Definitions • Urban stormwater - “net increase in run off and decrease in groundwater recharge resulting from the introduction of impervious surfaces such as roofs and roads within urban development” • “Urban stormwater” is only available within the urban growth boundary • Base/dry weather flows in drains & waterways are not considered urban stormwater - no access to base flows will be permitted Results through Experience

3. Current allocation rules for stormwater harvesting (DSE Sustainable Water Strategy – 2006) • If stormwater is flowing to the sea via a drain, 100% of the stormwater may be harvested • If stormwater is flowing to a stream from an existing development up to 50% of existing stormwater can be harvested for use and 50% is reserved for the environment • If there is a scheme to harvest more than 50% of the resource a study is required to assess implications for the environment • All stormwater generated from new development is available for harvesting with the aim of the development having no nett impact Results through Experience

4. Who Administers Stormwater Assets? The harvesting of water from Melbourne Water’s drains and waterways requires a licence under Section 51 of the Water Act1989. Results through Experience

5. Australian Rainfall Australian rainfall is low, seasonal and highly variable compared with other continents such as Europe and North America Results through Experience

6. Rainfall patterns Results through Experience

7. Annual rainfall Melbourne Results through Experience

8. Rainfall – monthly distribution Results through Experience

9. Typical irrigation demands (Melbourne) Results through Experience

10. Some thoughts.. • Rainfall is cyclical meaning there are peaks and troughs • The demand for water could also be cyclical e.g. irrigation • Distribution of “peaks and troughs” in a year can be more important than the total annual rainfall • Statistical Average Rainfall data can be misleading • Selection of the rainfall years for further modelling is a risk – based exercise Results through Experience

11. Stormwater Harvesting Scheme Major Components Results through Experience

12. Results through Experience

13. Diversion of flows Results through Experience

14. Diversion Structures • divert the pre-determined range of flows for harvesting • while allowing flows outside of this range (larger/by-pass flows and smaller base/environmental flows) to continue via the designated conveyance system These functions could be delivered by various controlling mechanisms generally falling into the two major categories… Results through Experience

15. Flow Diversions • i) Transverse weir • Side weir • Drop structure • Flow Control • i) Throttle pipe • ii) Adjustable Penstock • iii) Hydrobrakeor similar proprietary device • iv) Orifice plate/Sutro weir Results through Experience

16. Treatment for reuse - Stormwater Results through Experience

17. National Guidelines Results through Experience

18. State guidelines Results through Experience

19. Overview of Treatment Requirements - Stormwater • Small to medium schemes • No supply to third parties • Unrestricted spray irrigation • Requirements are to achieve: • Disinfection to achieve >2.5 log reduction in viruses, parasites and bacteria • EC < 10 CFU/100 mL • Turbidity 10 – 25 NTU (subject to satisfying disinfection requirements) http://www.ephc.gov.au/ephc/water_recycling.html Results through Experience

21. Storages Above ground Underground Results through Experience

22. Example one – for those who love bright colour… Results through Experience

23. and for those who are more traditional with colour… Results through Experience

24. and for those who use concrete and concrete only Results through Experience

25. and the above ground tanks… Results through Experience

26. Distribution system Results through Experience

27. Distribution Pipe Work • Colour coded pipes (lilac) • Removable handles for hose taps • Signage e.g. “Recycled Water – Do Not Drink” • Allow flush valves for periodic flushing of the system Results through Experience

28. Definition of Volumes Results through Experience

29. Operation & Management of Stormwater Harvesting Schemes Results through Experience

30. O&M itemized • Catchment management • Incident response (oil spillage, pumps failure etc) • OH&S (e.g. confined space entry requirements) • Regular inspections • Maintenance of equipment (cleaning) • Monitoring Results through Experience

31. ACKNOWLEDGEMENTS In preparation of this presentation the author would like to acknowledge the support and contribution from the following professionals: • Steve Hosking, Melbourne Water Corporation • Water & Carbon Group • Daryl Stevens, Atura Pty Ltd • Murray Powell, Optimal Stormwater Pty Ltd Results through Experience

32. QUESTIONS TIME… Results through Experience

33. Results through Experience THANK YOU