sustainable water civil design
DESCRIPTION
Water masterplanning and drainage design in the UK. Problems, issues and challenges.TRANSCRIPT
INTRODUCTION, FAILURES AND SUCCESSES
Surface water drainage systems developed in line with the ideals of sustainable development and address the consequences of climate change.
They are collectively known as SUDS.
They are being implemented right across the world as the importance of water increases (excluding permafrost regions).
They are designed to:
Manage the environmental risks resulting from Urbanisation
Contribute to environmental enhancement.
Minimisation of the impact from the development on the quality and quantity of the runoff and maximise amenity and biodiversity opportunities. The extent to which this is possible depends on the site, but the ideal is they have equal standing. All SUDS systems needs to have at least 2 of the 3 elements:
Amenity &
Biodiversity
Quality Quantity
What ARE WE TRYING TO ACHIEVE?
Reduce run
off rates
Reduce run off
volumes
Encouraging
groundwater recharge
Reducing pollutant
concentrations and a
buffer mechanism
Enhanced
amenity and
aesthetic value
Enhancing
biodiversity
What does not count as SUDS?
Giant tanks with impermeable liners NO VOLUME REDUCTION – NO GROUNDWATER RECHARGE NO WATER TREATMENT – NO ECOLOGICAL AND NO BIODIVERSITY VALUE MOST DRAINAGE DESIGN PRE 1990
PEAK ATTENUATION REDUCTION
Flow (m3/s)
Time
Without attenuation
With attenuation
EU Water
Framework
Directive 20/60/EC
Buildings
Regulations various
amend.
Flood Water
Management Act
2010
Water Industry Act
1991
Various other Water
Bills
Water Resources
Act 1991
Land Drainage Act
1991
Groundwater
Regulations 1998
Discharge to
groundwater
•Soakaways, Swales, permeable
block paving and other source
control
Discharge to
watercourse • EA or LDA approval and
controls
Discharge to
surface water sewer • Automatic right
removed
Discharge to
combined sewer
Adoptable
standards
2013
Must treat
first 5mm
Located in
accessible
location
Early
engagement
prior to
planning
Minimum
construction
standards
Appointment of experienced Civil Engineer very early in
project
In public highways Or public areas, not back gardens
If you can’t infiltrate at all then harvesting is likely to be necessary
Not onerous, but sensible and practical
Drainage Impact / Drainage Strategy Reports necessary as per Scotland
Problems included:
Very low infiltration
No surface water sewer within 80m
No watercourses within 200m
High groundwater level (seasonal)
Porous Asphalt Permeable block Paved Car Parks Quality Quantity
Rainwater Garden Quantity Amenity Biodiversity Health
Landscaping swale Attenuation Biodiversity
Maximising Source control techniques
and wetted perimeter
RWPS
Small internal courtyard
Attenuation crates
Fountain pump Storm water storage
High level overflow to public sewer
RWPS from roof
Residential flats with underground car park
Basement
Storm water attenuation and separation prior to borehole
Flats
Car park flow To foul sewer
Boundary
Impermeable ground
Stephen Gibson, Director – Wilsham Consulting E [email protected] T 01235 529646 M 07449948261 W www.wilsham.co.uk Wilsham provide civil engineering professional services across a very wide spectrum of developments, from hotels, private luxury houses, estate water master-planning, churches, water companies, cathedrals, schools and health facilities. This includes: • FRAs, Residential and commercial estate water master-planning, • Drainage Impact / Strategy Reports to support SAB applications • Highway Design, • Waste water design, • Groundwater and flood mitigation • Engineering advice to water company legal groups