Transcript Sustainable Development

SUDS and Sustainability
Kate Heal, University of Edinburgh
Neil McLean, SEPA
Brian D’Arcy, SEPA
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
?
Sustainable Development
• 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'.
Environmental
The Sustainability
Triangle
Economic
Social
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?
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)
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
The SUDS Triangle
• Water Quality
– SEPA
• Water Quantity
– Local Authority
• Habitat/Amenity
– SNH
Habitat/Amenity
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.
Social Issues (ii)
– 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
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
Source; Campbell et al, 2004
– Over 6,000 km of waterbodies
“at, or probably at, significant risk”
from diffuse pollution
– Urban runoff
– Bathing waters
• SUDS can help !
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!!
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
Estimated relative mass flow (%) of copper in different
urban drainage systems for Sankt Gallen, Switzerland,
(75,000 inhabitants) (after Boller, 1997)
Combined
sewer
Separate
sewer
Separate
stormwater
infiltration
Treatment plant
5
2
2
Agriculture/deposit
71
23
23
Soil
0
0
68
Surface water
24
75
7
Groundwater
0
0
?
Anthropogenic metal accumulation in top 5 cm soil over
8 years, Göteborg, Sweden (Lind & Karro, 1995)
g m-2
10
Infiltration area
Reference area
5
0
Zn
Pb
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
Cu
Introductions with planting (Lancaster, 2003)
Q rap
G
are
uickTim
needed
hics e™
deco
toand
se
mpresso
eathis picture.
r
1500
Macroinvertebrates
- immature snails
1000
Abundance (No/sample)
500
0
12000
11000
Immature snails
1000
0
99 00 01 02
Halbeath
99 00 01 02
Linburn
99 00 01 02
99 00 01 02
Wetland
Pond 7
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
Poor design, construction &
maintenance
•Blocked & broken inlets
•Inlet to perforated pipe
covered with sediment
(Images: Wolfram Schluter,
Ewan Associates)
Inlet to
trench
Bypass
Inlet
Groundwater inputs to Linburn
Pond (Morgan, 2004)
• Data from UWTC, University of Abertay:
– Continuous rainfall for DEX catchment
– Continuous outflow for Linburn Pond
Total inflow (10% Max possible inflow Total observed
impermeable
(100% impermeable
outflow
surface)
surface)
5.33 x 107 l
5.33 x 108 l
6.36 x 108 l
• Outflow > maximum possible inflow
Simulated
Inflow
v Observed
and Modelled
Outflow
for Linburn
Pond May
Inflow
v Observed
Outflow
for Linburn
Pond May
2000-2001
450
2000-2001
450
400
400
350
350
Flow
Flow
(l/s)(l/s)
300
300
250
250
200
200
150
150
100
100
50
50
0
0
May-00
Jun-00
Jul-00
Aug-00
Sep-00
Oct-00
Nov-00
Dec-00
May-00
Jun-00
Jul-00
Aug-00
Sep-00
Oct-00
Nov-00
Dec-00
Time (months)
Time (months)
Inflow
Inflow
Observed Outflow
Observed Outflow
Modelled Outflow
Increasing the sustainability of SUDS
• Surface water management train
• Improved design at all scales:
– Design with development
– Design for maintenance
Swale, Waterside
– Design detailing
Gardens
Construction swale,
• Community
engagement from start
Waterside Gardens
• Multi-disciplinary approach
“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
Sustainable
development
is “adesign
journey
conventional
techniques”
(CIRIA C521,
and not&aNorthern
destination”
manual for Scotland
Ireland)
development is an opportunity…