1. Stormwater Management
Beat Stauffer, seecon international gmbh

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3. Contents
Concept (Rural and Urban)
How can Stormwater Management Optimise SSWM
Design Principles (Storage and Infiltration Types)
Health and Costs
Operation and Maintenance
Applicability
Pros and Cons
References

4. What is Stormwater Management?
1. Concept
What is Stormwater Management?
Why:
Surface runoff has to be reduced to prevent flooding
Especially in urbanised areas where natural infiltration is reduced
Sediments and Pollutants (e.g. nutrients from agriculture) must be removed
How:
Temporary storage (e.g. retention ponds, rainwater harvesting)
Infiltration (e.g. grass filter stripes, infiltration basin)

5. Rural Stormwater Management
1. Concept
Rural Stormwater Management
Causes: heavy rainfalls, storms, roads, buildings, overstrained sewer systems
Impacts: flooding and stream erosion
Benefit of flood events and precipitation: use this water for irrigation
Some available techniques:
Spate irrigation
Micro basins
Sand Dams
Field trenches
Rainwater harvesting
Flooded agricultural land after a storm event. Source: ARC (2010)

6. Rural Stormwater Harvesting
1. Concept
Rural Stormwater Harvesting
Rooftop harvesting and storage for further use. Source: DOLMAN & LUNDQUIST (2008)
Spate irrigation system Yemen. Source: FAO (2012)
Sand accumulates until the dam is completely full of sand up to the spillway. Water is stored within the sand, protected and filtered, making up to 40 % of the total volume. Source: ED (n.y.) 

7. Urban Stormwater Management (CSIR 2000; PARKINSON et al. 2010)
1. Concept
Urban Stormwater Management (CSIR 2000; PARKINSON et al. 2010)
Human settlements disturb the natural water cycle and creates floods and water pollution:
Natural vegetation is often removed and rivers are canalised
Surfaces are impermeable
Groundwater resources decrease, fresh water becomes scarce
Let’s upgrade the urban water cycle! Source: AUCKLAND CITY COUNCIL (2010)

8. Urban Stormwater Management – IUWM Approach (UNEP 2009)
1. Concept
Urban Stormwater Management – IUWM Approach (UNEP 2009)
Integrated Urban Water Management (IUWM):
The practice of managing freshwater, wastewater, and stormwater as links within the resource management structure, using an urban area as the unit of management.
Including:
Consumption efficiency
Ensure water quality
Alternative sources (e.g. rainwater)
Engage communities
Establish and implement policies and strategies
Support capacity development of personnel and institutions
Improve economic efficiency of services

9. 2. How it can optimise SSWM
Stormwater Management helps to collect, treat and (re-)use runoff water; to avoid contamination and destruction; and to restore the disturbed urban water cycle!
Source: SEECON (2010)
Source: SEECON (2010)

10. Urban Stormwater Management – An Overview
3. Design Principles
Urban Stormwater Management – An Overview
There are several techniques to manage surface runoff. They are divided in two groups:
Storage Type Devices
Infiltration Type Devices
What technique is implemented should be decided on local conditions and responsible planers.
The sewer system cannot handle the volume of runoff. Source: USGS (2009)

11. Detention Ponds (PARKINSON et al. 2010; NJDEP 2004)
3. Design Principles – Storage Type Devices
Detention Ponds (PARKINSON et al. 2010; NJDEP 2004)
Excavated reservoirs or natural depressions.
Dry during low flow periods -> temporary storage during flood events
Stormwater should stored long enough to settle solids
Extended Detention Basin Components. Source: NJDEP (2004)

12. Retention Ponds (PARKINSON et al. 2010)
3. Design Principles – Storage Type Devices
Retention Ponds (PARKINSON et al. 2010)
Primarily designed to improve stormwater quality.
Secondary for flood control devices.
Retention Ponds do not dry out, water stays between 2 and 4 weeks.
Water quality improvement mainly through settling.
A retention pond with additional aeration, which improves aquatic life and pollutant removal. Source: KASCO MARINE (n.y.)

13. Onsite Detention (OSD) (PARKINSON et al. 2010; UPRCT n.y.)
3. Design Principles – Storage Type Devices
Onsite Detention (OSD) (PARKINSON et al. 2010; UPRCT n.y.)
Collecting stormwater on-site (e.g. on a private property).
Storing it for a certain time and release it slowly or (re-)use it.
Used in urban and residential areas.
A possible OSD design with modular tank boxes. Source: ATLANTIS (n.y.)

14. Rainwater Harvesting (TRCA & CVC 2010)
3. Design Principles – Storage Type Devices
Rainwater Harvesting (TRCA & CVC 2010)
Can be used in urban and rural areas.
Reducing of stormwater runoff and storage of potable water
Water can be used for irrigation, as flush water for toilets or, after purification, as drinking water.
Rooftop rainwater harvesting in Urban Areas using a Plastic Tank. Source: VISHWANATH (n.y.)

15. Green Roofs (living roofs) (TRCA & CVC 2010)
3. Design Principles – Storage Type Devices
Green Roofs (living roofs) (TRCA & CVC 2010)
Vegetated roofs on flat or sloped roofs.
They improve energy efficiency, reduce urban heat effect and create green spaces.
Reducing peak flow (storing a certain volume of rainwater)
Green Roof in Basel, Switzerland. Source: GREENROOFDESIGN (2008)

16. Constructed Wetlands (Auckland CITY COUNCIL 2010; METROCOUNCIL n.y.)
3. Design Principles – Storage Type Devices
Constructed Wetlands (Auckland CITY COUNCIL 2010; METROCOUNCIL n.y.)
Designed to manage peak flows and to improve water quality of surface runoff.
Restoring natural habitats in cities (recreation, birdlife, etc.).
A possible design is a pond/wetland system. First pond (left) reduces velocity and removes pollutants. The shallow marsh system stores water and is an additional treatment. Source: METROCOUNCIL (n.y.)

17. Infiltration Trenches (DEP & CZM 1997; PARKINSON et al. 2010)
3. Design Principles – Infiltration Type Devices
Infiltration Trenches (DEP & CZM 1997; PARKINSON et al. 2010)
Shallow excavations filled with uniformly crushed stones.
Walls and top lined with geotextile to avoid sediment penetration.
Runoff infiltrates through the trenches into the subsoil.
Treatment occurs during infiltration.
Constructed beside streets and outdoor parking lots.
Design of infiltration trenches. Source: RIVERSIDE (n.y.) and SUSTAINABLE STORMWATER MANAGEMENT (2007)

18. Grass Filter Stripes (BARR ENGINEERING COMPANY 2001)
3. Design Principles – Infiltration Type Devices
Grass Filter Stripes (BARR ENGINEERING COMPANY 2001)
Densely vegetated and graded areas.
Slowing runoff velocity, trapping sediments and pollutants and providing modest infiltration.
Grass filter stripe in combination with infiltration trenches (stone drop) and forest filter. Source: BARR ENGINEERING COMPANY (2001)

19. Grassed Swales (PARKINSON et al. 2010; TRCA & CVC 2010)
3. Design Principles – Infiltration Type Devices
Grassed Swales (PARKINSON et al. 2010; TRCA & CVC 2010)
Open grassed channels, which allow an infiltration along the course.
Check dams and vegetation reduce velocity, and allow sedimentation, infiltration, evapotranspiration and contaminant removal.
Enhanced grass swales feature check dams that temporarily pond runoff to increase pollutant retention and infiltration and decrease flow velocity. Source: TRCA & CVC (2010)

20. Pervious Pavements (TECOECO n.y.)
3. Design Principles – Infiltration Type Devices
Pervious Pavements (TECOECO n.y.)
Permeable pavement surface with a stone reservoir underneath.
Reservoir stores runoff water temporarily.
Afterwards, stored water is subsurface drained or infiltrates into the subsoil.
A theoretical cross section of porous pavement (left) and porous pavement during a demonstration. Source: TECOECO (n.y.)

21. Infiltration Basin (NJDEP 2004)
3. Design Principles – Infiltration Type Devices
Infiltration Basin (NJDEP 2004)
Constructed facility with highly permeable soils.
Water infiltrates into surrounding soil and gets treated.
An infiltration basin. Source: VUSP (n.y.)

22. 4. Health and Costs
Health Aspect
General aim: protect health, welfare and safety of the public.
The described technologies all have ecological treatment effects.
Illegal solid waste disposal or connection of sewer system to the stormwater drainage systems can endanger the public health.
High sedimentation loads could clock infiltration systems and lead to ponding water surfaces mosquito breeding.
Costs
Costs depend on the technology, topography and expert knowledge.
A proper stormwater management avoids high costs caused by flood damages.
Collected water can be reused for groundwater recharge, urban landscaping or farming, etc.

23. 5. Operation and Maintenance
A proper organised O&M service is essential to:
Extend the lifespam of stormwater systems.
Improve the site drainage.
Reduce pollution entering surface waters and groundwater.
6. Applicability
Necessary in every urban or rural settlement to:
Protect human health;
Prevent water pollution;
Collect and (re-)use precipitation water;
Prevent damages on infrastructure
It has to be adapted to the local conditions (climate, topography, resources, etc.)

24. 7. Pros and Cons Advantages: Proper drainage of surface run-off
Collected water can be reused for groundwater recharge, urban landscaping or farming, etc.
Treatment of stormwater in a very early stage
Avoids damages on infrastructure (private properties, streets, etc.); flood prevention
Can be integrated into the urban landscape and provide green and recreational areas
Disadvantages:
Expert planning, implementation, operation and maintenance required
Depending on technique a lot of operation and labour
Risk of clogging infiltration system caused by high sedimentation rates.

25. 8. References
ATLANTIS (Editor) (n.y.): Modular Underground Tanks System. Sidney: Atlantis. URL: [Accessed: ]
AUCKLAND CITY COUNCIL (Editor) (2010): Stormwater. Auckland: Auckland City Council. URL: [Accessed ]
ARC (Editor) (2010): The Countryside Living Toolbox: A Guide for the Management of Stormwater Discharges in Countryside Living Areas in the Auckland Region. Auckland: Auckland Regional Council (ARC). URL: [Accessed: ]
BARR ENGINEERING COMPANY (2001): Urban Small Sites Best Management Practice Manual. Filter Stripes. St. Paul: Metropolitan Council Environmental Services. URL: [Accessed: ]
CSIR (Editor) (2000): Guidelines for Human Settlement Planning and Design. Pretoria: CSIR Building and Construction Technology. URL: [Accessed: ]
DEP (Editor); CZM (Editor) (1997): Stormwater Management. Bosten: MA Department of Environmental Protection (DEP) and MA Office of Coastal Zone Management (CZM). URL: [Accessed: ]
DOLMAN, B.; LUNDQUIST, K. (2008): Roof Water Harvesting for a low Impact Water Supply: Featuring the Brazilian Ball Pre-Filter System: A Case Study. Occidental: The WATER Institute Occidental Arts and Ecology Center (OAEC) . URL: [Accessed: ]
ED (Editor) (n.y.): Pioneers of Sand Dams. Brentford: EXCELLENT DEVELOPMENT (ED). URL: [Accessed: ]
FAO (Editor) (2010): Guidelines on Spate Irrigation. Rome: Food and Agriculture Organization (FAO). URL: [Accessed: ]
GREENROOFDESIGN (Editor) (2008): Messehalle Basel. Zurich/London: Green Roof Design. URL: [Accessed: ]
KASCO MARINE (Editor) (n.y.): Retention Ponds. Prescott: Kasco Marine, Inc. URL: [Accessed: ]
METROCOUNCIL (Editor) (n.y.): Constructed Wetlands: Stormwater Wetlands. Saint Paul: Metropolitan Council. URL: [Accessed: ].
NJDP (2004): Standard for Infiltration Basins. New Jersey: Department of Environmental Protection.URL: [Accessed ]

26. 8. References
PARKINSON, J.N.; GOLDENFUM, J.A.; C.E.M. TUCCI (2010): Integrated Urban Water Management: Humid. Paris: UNESCO.
UNEP (Editor) (2009): Integrated Urban Water Management. Osaka: United Nations Environment Programme (UNEP). URL: [Accessed: ]
RIVERSIDES (n.y.): Infiltration Trenches. Toronto: RiverSides Stewardship Alliance. URL: [Accessed: ]
SUSTAINABLE STORMWATER MANAGEMENT (2007): Infiltration Trenches. URL: [Accessed: ]
TECOECO (n.y.): Permeconcrete. Glenorchy: TecEco Pty Ltd. URL: [Accessed: ]
TRCA (Editor); CVC (Editor) (2010): Low Impact Development Stormwater Management Planning and Design Guide. Downsview and Mississauga: Toronto and Region Conservation Authority (TRCA) and Toronto and Region Conservation Authority (CVC). URL: [ ]
UPRCT (n.y.): What is On-site Stormwater Detention? Parramatta: Upper Parramatta River Catchment Trust (UPRCT). URL: [Accessed: ]
USGS (Editor) (2009): Miscellaneous September 2009 Flooding Pictures. Reston: United States Geological Survey (USGS). URL: [Accessed: ]
VUSP (Editor) (n.y.): Design Components. Villanova: Villanova Urban Stormwater Partnership (VUSP). URL: [Accessed: ]

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