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Surface Water Management for Resilient Cities GI/SuDS Opportunities and Challenges
Zorica Todorovic
3rd July 2019
SuDS in the City
Manchester
Sustainable surface water management - What is SuDS? Why we need SuDS?
New build – opportunities/challenges, case studies
Retrofit – opportunities/challenges, case studies
Strategic approach
Conclusions
Content
Half of the world’s population
now live in cities and this will
reach 60% by 2030
and 75% by 2050
Urbanisation puts huge environmental pressures
Future Development Plans Urban Creep Climate Change System Ageing
Increased costs of dealing with storm water
• Need to
• Reduce runoff volume
• Reduce runoff rate
• Mitigate diffuse pollution
• Provide environmental benefits
• Is there a better way?
Why SuDS?
Infiltration
Attenuation (traditional or SuDS) with discharge to
• Watercourses
• Sewers
More green areas
Taking water back to its natural path
Why SuDS?
Types of SuDS
Green/blue roofs Raingardens BioretentionBox raingardens
Swales Ponds Wetlands Tree pits
SoakawaysGravel pavementsFilter drainsPermeable pavements
Amenity/Biodiversity Covers:
Aesthetic
Ecological quality of the landscape
Increased wellbeing
Wildlife habitats
Recreation opportunities
Educational opportunities
Water as a resource
Increase in land values
Decrease in deprivation areas
Why SuDS?
How developments could mimic natural flow patterns?
Contributing to the quality of
blue and green infrastructure
Global trends – SW BMP, LID,
WSUD, SuDS, Sponge Cities
£2.1billion
The amount the UK government estimated could be saved in healthcare costs if
every household in England were provided with good access to quality green space
City Resilience
Green Agenda
Natural Capital
Biodiversity Net Gain
Reduction in Air Pollution
Low Carbon Agenda
Place Making
Drivers
Standard of protection increases
2, 5, 30 year storms
100 year storms - allowance for climate change 40%
Large attenuation tanks - flash floods
How to manage flows?
Why SuDS?
Managing Water on Surface
Typical inlets in cities Could it be different – easier to maintain maybe more green
SuDS in the City?
20, 50 , 100 years?
Infrastructure upgrade
Regeneration opportunities
New development
1)
Way to Resilient CitiesB
udget constr
ain
ts
Le
gis
lative
fra
me
wo
rk
Be
st p
ractice
2) Incremental opportunistic retrofit steps
Strategic solutions/Policy 3)
SuDS in New Developments
New Build – Low Density
Finberry, Ashford
New Build – Medium Density
St Andrews Park, Uxbridge
New Build – High Density
London's green
roof area reaches
1.5 million
square metres
New Build – High Density
Manchester, Princess Street Manchester, Circle Square Apartment Block, Upper Chorlton Road
Mixed Use Development, Oldham Road…
Regeneration Opportunities
Thames Water Twenty 4 Twenty
Battersea Nine Elms, London
ManholesCatchpit ChambersPipesDrainage ChannelsGulliesFilter DrainsAttenuation TankFlow Control UnitSmart FilterGreen Roof Area
Regeneration Opportunities
Circle Square, Manchester Old St Mary’s Hospital, Manchester Hardman Court, Manchester
New Build Lessons Learnt
Planners need support in setting criteria - urban greening factor?
Need for upfront planning for GI/SuDS as part of the development
Procurement - cooperation of landscape and drainage
Multifunctional spaces
Inlets – attenuation - ease of upgrade and maintenance
Clear maintenance/adoption route
Planning – building control
20
SuDS Retrofit
Need for SuDS Retrofit
Every location could be an opportunity
Will they create the multiple benefits?
• Neighbourhoods and streets will continue to be
rejuvenated and enhanced
• Roads resurfacing and sites refurbishments
• Large extensions
• Public buildings
Major incentives and engagements required –
commercial sites, schools, residents
Design and implement affordable and socially acceptable
retrofit climate change adaptation measures in social
housing landscapes.
Support the achievement of wider GI goals
Implement main measures through employment
programmes for long-term unemployed and develop a
set of training courses for maintenance professionals
Develop a methodology for resident engagement
Evaluate technical performance and social return on
investment
03.ha hard surfaces drained to SuDS, hold 110m3
volume of water, £450k cost
Retrofit Residential
London Housing Estate, LBH&F
Source London.gov.uk
Retrofit Schools
All Saints School, Newmarket
Delivered in 4 months from inception to delivery
1400m2 (equivalent to the size of over five tennis courts) of impermeable surface disconnected
Saves 900m3 of water from being treated each year – enough to fill eight double decker buses
• Moorland School, Manchester
• BITC project
• Schools could save up to £1.75m a year for education budgets if all the city’s 1,300
schools adopted similar measures
• 85,000 Young people would benefit from access to green space
• 4,000 Tonnes of carbon pa, equivalent to 1500 cars could be
sequestered
• 54 Tonnes of air contaminates would be removed within 40
years
• 20,000 m2 of new green space would be created
• 350 Swimming pools of water could be held by SuDS
at any one time - 130,000 m3
Retrofit Schools
Retrofit Roads
• Counters Creek, London, LNH&F
• Melina Road • Mendora Road • Arundel Gardens
Source Susdrain: I Titherington, CCC
Retrofit Roads
Removing 155,000sqm of impermeable area
Releasing capacity for 6000-12,000 new homes
Annual monetarised benefits of £250,000
16,500sqm increase in green space
400 additional trees
• Grange Town, Cardiff
Source Susdrain
Retrofit Public Realm
• Shefield Grey to Green
Peak inflow for the 1 in 30 year 60
minute rainfall event is reduced from
47.3l/s to 6.3l/s
Peak inflow for the 1 in 100 year 60
minute rainfall event is reduced from
69.6l/s to 9.2l/s
Peak inflow for the 1 in 100 year (+30%
CC) 60 minute rainfall event is reduced
from 92l/s to 12.1l/s
Retrofit Lessons Learnt
Difficult and costly to implement but necessary
No planning requirement to influence
Working in partnerships between range of stakeholders is
essential!
Lengthy stakeholders engagement process
No straight forward way to capture multiple needs
Different funding cycles for match funds
Incentives – funding mechanisms – Ignition project
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Strategic SuDS
Linking Strategic Initiatives
Inform Planning and
Strategic Opportunities
Ignition
Natural
Course
UU SuDS
Maps
Manchester
LAP
Natural
Capital IP
MCC G&B
TGAP
• Need for a strategic plan
across areas to be
implemented in stages as
drivers (and funding)
becomes available
• This will result in holistic
solutions in the long term
It’s the ‘right time’
Planners need support in defining criteria – partnerships essential
Systems need to be designed to meet multiple functions
• Integrated approach in design – procurement of design services
• Flexibility needs to be inbuilt in design
• Need to attractive maintainable porous pavement materials
• Ease of maintenance a paramount
• Planning – building control
Need for best practice and city’s standards
Steep learning curve – pilots valuable evidence to build best
practice for the City
Conclusions
