Sustainable Urban Drainage

1
Sustainable Urban Drainage

• Alan Jones
• (Alan.Jones_at_ed.ac.uk)

2
Sustainable Drainage

• A concept that focuses on the environment and
  people.
• Considers
• Quantity of runoff
• Quality of runoff
• Amenity value of surface water
• Existing urban drainage systems are
• Unsustainable in the long-term
• Damaging to the environment

3
Why are SUDS needed?
Hydrograph
Discharge
Time

• SUDS
• Attenuate flow
• Promote infiltration groundwater recharge

4
Why are SUDS needed?

• 11 of Scottish river length is classified as
  polluted due to contamination from urban drainage

• SUDS aim to protect watercourses from
  point/diffuse pollution by acting as sinks for
  contaminants
• Cost implications for maintaining long-term
  performance of SUDS

5
Why are SUDS needed?

• Amenity
• A loaded term when used in relation to SUDS
  environmental/community issues
• Covers
• Aesthetic Ecological quality of the landscape
• Land-use
• Wildlife habitats
• Land-values
• Recreation opportunities
• Educational opportunities
• Water-resources
• Other factors
• Opportunity costs
• Perceptions of risk
• Construction impact

6
SUDS Triangle
7
Present Legal Status

• WFD Water Framework Directive (2000)
• Prevent deterioration in water status
• Restoration of surface waters to good ecological
  and chemical status by 2015
• Reduction of pollution from priority substances
• Contributing to mitigating the effects of floods
  and droughts
• Preventing/limiting pollution input into
  groundwater
• CAR The Water Environment (Controlled
  Activities) (Scotland) Regulations (2005)
• Surface water-runoff in areas constructed, or
  construction sites operated, after 1st April 2006
  must now be drained by a Sustainable Urban
  Drainage System
• Exceptions Single dwellings or if the discharge
  is to coastal water

8
Conventional Drainage
Precipitation Rainfall/Snow
Rapid conveyance of water pollutants
Local watercourse
9
SUDS Drainage The treatment train approach

• Connect SUDS together
• Individual function of local SUDS techniques
  beneficial but design should be led by a
  holistic vision approach
• Combined integrated function mimics the
  waterflows in the natural hydrological cycle
• Surface Flow
• Infiltration
• Storage in water-bodies
• Interflow
• Evapotranspiration

10
Treatment Train

• Good Housekeeping best practice to eliminate, or
  minimise, pollutants being generated and allowed
  into the environment.
• Source Controls methods of dealing with runoff
  at source, e.g. permeable paving, filter strips,
  or roadside filter trenches.
• Site Controls local controls that deal with
  generally smaller catchment areas, e.g. detention
  basins.
• Regional Controls larger components that might
  typically deal with larger catchments and
  upstream site controls, e.g. stormwater wetlands
  and retention ponds.
• (Heal, 2004)

11
A variety of techniques
Drainage conveyance
Kerb design
Roof drainage reuse
Detention Basins
Filter Drain
Swales
12
Retention Ponds

• Falkirk Stadium Retention Pond (Undeveloped
  catchment)

13
Retention Ponds / Wetlands

• Lidl Distribution Centre, Livingston - Retention
  Pond (Loading bay, Carpark runoff)

14
Tackling Contaminants

• The flood-reducing benefits of SUDS are
  obvious...
• Store water at various points in the catchment
  and allow water to be re-used, infiltrated,
  released slowly and/or evaporated.
• These processes also allow the trapping of
  potential contaminants (e.g. metals,
  PAHs/Hydrocarbons) within the treatment train.
• Contaminants are typically adsorbed
  (physico-chemically bonded) to sediment particles
  that are entrained in flow.
• As water speed is slowed down using SUDS,
  particles (and therefore contaminants) settle out.

15
Contaminant Sources Vehicles

• 15-fold increase in the number of car and taxi
  miles covered over the last 50 years!

SUSTAINABLE (?)
Campbell et al. (2004)
16
Land-Use Contamination
(Beasley and Kneale, 2002)
17
Design - Site Constraints

• Physical site constraints can make construction
  difficult or impossible, and maintenance
  expensive if not addressed adequately. Factors to
  consider include
• topography - e.g. steep slopes
• soils and geology - e.g. erosivity, porosity,
  depth to bedrock or instability
• groundwater - e.g. geochemistry and water table
  depth
• space - limited open space, proximity to
  underground services. (e.g. gas, power)
• Social constraints include issues of health and
  safety, aesthetics and impacts on recreational
  facilities. Factors to consider include
• odour problems
• visual impacts
• noise
• physical injury - resulting from unauthorised
  access to structures
• contamination - infection, poisoning or injury
  caused by trapped pollutants or algal blooms
• vermin - e.g. mosquitoes, rats.

18
Design Maintenance Issues

• Not only can a poorly maintained SUDS technique
  function ineffectively, it can become a source of
  pollution or flood hazard itself.
• When designing a SUDS measure, the following
  points should be considered
• ease of maintenance and operation - the selected
  treatment should be easy and safe to maintain and
  operate
• extent of maintenance - ensure the maintenance
  requirements are within the operator's capability
  
• access to the treatment site - consider the ease
  of site access, when reviewing the treatment's
  maintenance requirements
• frequency of maintenance - ensure that resources
  are available to carry out maintenance at the
  required frequency
• debris and pollutant clearing - during clearing,
  the treatment should not require direct human
  contact with debris and trapped pollutants
  (automated clearing options are preferred)
• disposal - consider the disposal requirements of
  any waste from the treatment process.

19
Case Study J4M8

• SUDS development (c. 2000)
• Previously agricultural land
• Now a distribution hub based mid-way between
  Edinburgh and Glasgow

20
J4M8 Oblique Aerial Photograph