Sustainable Urban Drainage Systems (SuDs)

Transcription

1 Sustainable Urban Drainage Systems (SuDs) Brendan Colgan, Chartered Engineer

2 Hydrological Cycle - managing the entire cycle is the goal

3 Disruption of the Hydrological Cycle

4 Why use SuDS? G Traditional Surface Water Drainage Drainage design has been extremely simple using a rational method to size pipes to ensure that surface water is removed as quickly as possible to ensure flooding does not take place on site. In transferring the surface water downstream, it provides a risk of flooding to other areas Pollution in the wash-off from the urban environment is conveyed into the natural environment. N O T W O R K IN

5 Environmental Management Full information on the justification, principles and application of sustainable drainage systems

6 CIRIA Documents

7 Why use SuDS? The Water Framework Directive (WFD) Directive 2000/60/EC of the European Parliament and of the Council of 23rd October 2000 Maintain high ecological status of waters where it exists, preventing any deterioration in the existing status of waters and achieving at least good ecological status in relation to all waters by Manage water bodies in a way that protects ecosystems and habitats. River Basin Management Plans and Programme of Measures

8 Why use SuDS? EU Floods Directive (2007) Flood Risk Management Guidelines 2009 Avoid development in areas at risk of flooding Manage risk, Avoid,Reduce and Mitigate Incorporate Flood Risk assessment Flood Zones A,B,C - high, moderate and low Adoption of SuDS

9 What is SuDS? Principles of Sustainable Urban Drainage

10 Levels The SUDS treatment train uses a logical sequence of SUDS facilities in series thus allowing run-off to pass through several different SUDS before reaching the receiving watercourse or water bodies. By using the treatment train, run-off will encounter different passive treatment processes that are active in different types of facilities.

11 For SuDs - Think Food! Cookbook = GDSDS Policy Document The Menu Starter = Source Main = Site Dessert = Regional Specials = New SuDs Devices Restaurant Guide = Dieting = Planning

12 Selecting Suds Technique Source Control Water butts, Filter Strips, Soakaways and Small Swales Site Control Swales, Detention Basins and Ponds Regional Control Detention Ponds, Reed Beds or Constructed Wetlands

13 SuDS in Fingal Pilot Scheme 1000 Butts for sale 40 each incl stand

14 SWALES

15

16 Filter strip Sheet flow from drained area Runoff filtered through vegetation Limited interflow and infiltration

17 Filter strips

18 Porous Pavements A type of pavement that allows rain to pass through it. It can be specialised asphalt or concrete, dry-laid interlocking pavers, or other materials.

19 Plastic Geogrid Grasscrete

20 Green Roofs Roofing systems specially designed to grow vegetation, normally consisting of a special waterproof and root repellant membrane, drainage system, filter cloth, lightweight growing medium, and plants.

21 Saint Vincents Hospital

22 Hydro-Brakes

23 Bioretention and Urban Streetscape (Portland, OR)

24 Infiltration Planters Another way to integrate landscape with architecture is to build planters that also manage stormwater. Portland, OR

25 Rainwater Harvesting Depending on design it may or may not be classed as a SuDS

26 Rainwater Harvesting Putting rainwater to work for garden or houseplant watering, for washing the car, or even for flushing toilets.

27 RW Harvesting Tank in Malahide Castle RW Tank 16m3 Under Coach Park Used to supply Toilets Also connected to Mains supply

28 Wet Detention Pond: last component in Treatment Train Overflow Grate Runoff Flood Control Pool (2(2- through year storms) Outlet Weir/Orifice Erosion Control Pool (2(2-year storm) 1 4 Wetland Vegetation 1 6 Uptake Littoral Zone Permanent Pool Runoff From 30 mm of Rainfall Normal Water Level Algal Uptake Solids Settling Outlet Pipe Discharge Adsorption Notes: 1. Runoff from 30mm of rainfall is detained in the pond for flood control, erosion control, and treatment by algal and vegetative uptake, solids setting, setting, and adsorption. adsorption 2. The runoff from the first 30mm of rainfall is detained above a permanent pool (with a wet season hydraulic residence time of 14 to 28 days) days) for treatment. 3. Storage recovery of runoff from 30mm of rainfall is required required in 48 to 72 hours.

29

30

31

32

33

34 Implementing SuDS in Fingal GDSDS Study (2005) Planning Acts and Regs Development Plan( and ) Local Area Plans ( ) Pre-Planning Consultations Assessment of Planning Applications Conditions Compliances

35 Development Plan Chapter 3 Green Infrastructure create an integrated and coherent green infrastructure by providing a network of green space Objective GI17 - Integrate provision for biodiversity with public open space provision and sustainable water management measures (including SuDS) where possible and appropriate. Objective GI29 - Ensure the provision of new green infrastructure addresses the requirements of functional flood storage and links with provision for biodiversity, Sustainable Drainage Systems (SuDS) and provision for parks and open space wherever possible and appropriate. Objective GI30 - Seek the creation of new wetlands and/or enhancement of existing wetlands through provision for Sustainable Drainage Systems (SuDS). Objective GI31 - Seek the provision of green roofs and green walls as an integrated part of SuDS and which provide benefits for biodiversity, wherever possible. Objective GI32 - Protect and enhance environmental conditions and water quality for existing rivers, streams, associated wetlands and groundwaters. Objective GI33 - Ensure that the creation of SuDS features and associated enhancement of wetlands reflects and enhances landscape character.

36 Chapter 4 Physical Infrastructure ensure that the county s infrastructure is developed in a sustainable timely and efficient manner Objective WT06 - Promote the appropriate use of Integrated Constructed Wetlands within the County. Objective SW01 - Protect and enhance the County s floodplains, wetlands and coastal areas subject to flooding as vital green infrastructure Objective SW04 - Require the use of sustainable urban drainage systems (SuDS) to minimise and limit the extent of hard surfacing and paving and require the use of sustainable drainage techniques for new development or for extensions to existing developments. Objective SW09 - Require the provision of regional stormwater control facilities for all Local Area Plan lands and Strategic Development Zones with a view to also incorporating these control facilities in currently developed catchments prone to flooding. Objective SW10 Require the inclusion of riparian strips of 10-15m for development on either side of watercourses.

37 SuDs Strategies for LAPs Appoint Consultant at early stage Involved in LAP process Assess existing Greenfield Situation Recommend appropriate SuDs Techniques Indicative rather than prescriptive Detail at Planning Application Stage

38 LAPs with SuDs Strategies Donabate Oldtown-Mooretown, Swords Baldoyle Portmarnock Rivermeade Cherryhound Kilmartin

39 Example 1 Donabate LAP (2007) Plan to build 5000 houses Area with a history of flooding Appoint Consultants at early stage Involvement in the LAP preparation

40 Surface Water Management Plan Selecting Suds Technique Source Control Water butts, Filter Strips and Small Swales Site Control Swales, Detention Basins and Ponds Regional Control Detention Ponds, Reed Beds or Constructed Wetlands

41

42

43 Surface Water Management

44 Example 2 Rivermeade LAP Development of 250 Houses Smaller Scale same process Assessment Recommendation

45 SuDs Assessment

46

47 Example 3 Portmarnock LAP Development of 1000 houses Adjoining Special Area of Conservation Adjoining Flood Risk Area Existing Hedgerows

48

49

50 Figure 2.4: GSI Geological Survey of Ireland Groundwater Vulnerability

51 Proposed Linear Park

52 Linear Park adjoining Station Road

53

54