green infrastructure & biodiversity, functional landscapes seminar, sue illman

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Water, water everywhere

…and water sensitive design

Green infrastructure and biodiversity….

….an inherent part of SuDS

Understanding why soft SuDS are important

and ensuring that you get them

November 2014

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Illman Young Landscape Design Ltd

A landscape and environmental

practice specialising in:

• Masterplanning and site design

• Landscape appraisals and environmental assessments

• Project planning through to site inspection

Our ambition:

To create innovative, practical and

sustainable landscapes

Our practice

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SuDS Research

• Illman Young in partnership with the University of Gloucestershire

• Completed 2 year research project

• Research into the design of SuDS that

are functional, attractive and

ecologically sound

• Investigation of existing schemes within

the UK and abroad

• Development of Good Practice

Guidelines and SuDS Training

• SuDS Pilot projects

• Ongoing relationship with university

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Concept

• System of surface water management

• Deals with water at source

• Infiltrate or attenuate

• Use soft features where possible

• Promote water quality

• Promote amenity and biodiversity

Components

• Green roofs

• Swales & infiltration trenches

• Rain gardens

• Stormwater planters

• Permeable paving

• Ponds and lakes

•Detention and retention basins

• Wetlands

Concept and components

What are SuDS?

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• Increased development creates extensive hard surfaces

• Sealing of ground prevents rain water from percolating into the soil

• Up to 80% of total rainfall turns into runoff within developed sites

• Larger amounts of water travel faster over hard surfaces

• Localised flooding

• Runoff traditionally collected in pipes

• Directed as quickly as possible into the nearest watercourse

• Problems of flooding and pollution

Traditional drainage

What is the problem?

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The problem

‘Urban creep’

Original Impermeable Surfaces - 1984

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The problem

Increase in impermeable surfaces

Current Impermeable Surfaces - 2009

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The problem

Increase in impermeable surfaces

Potential Impermeable Surfaces by 2034??

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Water Framework Directive Water Bill

Flood and Water Management Act

Legislative & environmental framework

Current context

Natural Environment White Paper Biodiversity 2020 UKNEA

The current context

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The answer

Integrated water management

• Catchment management at all scales

• Agricultural practices

• Flood alleviation

• Flood protection

• Town planning

• WSUD

• SuDS

• Retrofitting

• Building resilience

• … and nor forgetting better

management of water resources

But including – water resources

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• As the future becomes more uncertain,

manage water-based risks more

effectively

• Reduce the need for potable water

• Clean and recycle grey water on site

• Potential to manage black water

• Reduce risk from flooding

• Provides longer term cost certainty

‘Water Sensitive Urban Design is

the process of integrating water cycle management with the built environment Water sensitive urban design in the UK

through planning and urban design’ CIRIA

… but may be seen as a step too far

..… for now!

WSUD

The bigger picture

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• Not a huge step beyond where

we are

• Connects buildings with their

environment

• Connects team thinking

• Currently familiar with building

water reduction measures

• Increasingly familiar with SuDS

WSUD

Water sensitive urban design in the UK

CIRIA

The future direction

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• Protect watercourses from pollution

• Improve biodiversity and reinforce green

infrastructure networks

• Recharge groundwater and maintain flow

regime

• Health and socio-economic benefits

• Can respect & enhance landscape character

• Protect development from flooding

• Can be cheaper to construct

• Create attractive landscape features

& make efficient use of amenity space

• Can become economic assets by

making adjacent houses easier to sell/

achieve higher prices

• Allow development where full capacity

SuDS

Understand the benefits

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• Surface run-off increasingly causes flooding

• 5.5m homes or more are currently at risk

• £1.1 billion of insured damage each year

• June 2007 floods – £3.2 billion cost

2/3 properties flooded by drainage systems

• Traditional systems have limited capacity

• Sewer surcharging and pollution incidents

• Promote SuDS as an alternative

• Responsibility to sit with the LLFA

• Surface Water Management Plans

• Resolve adoption issues

Flood and Water Management Act 2010

SuDS Legislation

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SuDS

• National standards for SuDS

• Approval system for new development by the SAB

• County or unitary authorities to adopt and maintain

• No automatic right to sewer connection

• Compliance based adoption

procedures

• Planning permission can’t be

implemented without approval

• Register for SuDS

• Bond/penalties

SuDS Legislation

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(They were) Setting up their SAB

• Unitary authorities had no option but to expand their Drainage Department to deal with SuDS

• Most County Authorities are taking the same approach, and were recruiting new staff to fulfil this function

• Some were delegating the function of the SAB to the District Authorities who were similarly employing new staff

Detailed application guidance

• Some counties have/are producing their own

detailed guidance

• Reliance on the practical application of C697

Potential problems

• Slow start to the system and steep learning

curve, and some authorities very unprepared

• Lack of consistency in approach around the country

• Uncertainty over what is likely to be acceptable

How are/were local authorities responding?

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Current status of legislation

• National Standards were published

December 2011 for a 3 month

consultation period prior to their

finalisation…then continually postponed

• The secondary legislation has almost all

been put in place except Schedule 3

• Ministerial order was planned for April 2014 ……

• Then was expected October, but postponed….

• New consultation, putting responsibility

through DCLG and LPAs ended 24 October….

• Who knows………? Outcome December?

SuDS Legislation

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Format follows NPPF and takes an overarching approach Principles: • Sets standards that must be taken into account • Sets criteria for judging functionality of SuDS • Identifies exempt development on the basis of ‘disproportionate cost’

Standards: • For design, construction and maintenance

National standards for SuDS

What’s left?

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What’s not resolved

In principle • Underlying principle of reducing flood

risk not addressed • System becomes guidance not mandatory • Still doesn’t address anything other

than quantity In detail • How it works in the planning system • Where ‘advice’ comes from • How that’s funded • Thresholds for SuDS • ‘get out clause’ What was missing • automatic right of connection to a

sewer remains • adoption not resolved

The problems with the DCLG/Defra consultation

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What’s needed

Local Plans - effective policy base - inter-relate flood risk, SuDS, GI and landscape character - appropriate supplementary planning documents Development control - multi-disciplinary approach and within SAB - joint training and understanding - set requirements for outline and reserve matters/detailed planning Effective conditions - develop clear and deliverable model conditions - require delivery for phased development &soft establishment

How Planning can deliver

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Amenity/ Biodiversity

Quantity

Amenity/ Biodiversity

Quality

Quantity

Conventional drainage systems Sustainable drainage systems

SuDS Triangle

Quality

Replicating natural flows

Wildlife habitat

Reducing downstream flooding

Reducing riverbank erosion

Reducing sewer overflows

Improving water quality

Reducing misconnections

Watercourse protection

Groundwater recharge

Local flood management

Health and wellbeing

Biodiversity

Visual appearance

What makes them different?

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Hydrological Cycle

How does it work in nature?

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Inspiration from nature

How do SuDS work?

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… in the urban environment

How do SuDS work?

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Drainage techniques used in series

The Management Train

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Typical arrangement of SuDS components

The Management Train

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SuDS Design Requirements

• Greenfield Runoff Rate

• Greenfield Runoff Volume

• Return Periods

• Infiltration Rate

• PIMP – Percentage IMPermeable area

• Storage Requirements for interception,

attenuation and long-term storage

• Designing for exceedance

• Overland flood routes

Quantity

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• Protection of receiving watercourse

• Higher concentration of pollution near

beginning of storm “First Flush”

• Small, frequent events cause majority

of pollution

• Treatment Volume (Vt)

• Treatment Stages

• Groundwater Protection

Quality

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• Design SuDS as landscape asset

• Emphasize the use of vegetation

• Appropriate maintenance programme

• Informing and educating the public

• Retain and enhance natural drainage

systems

• Provide new habitats - damp areas and

wetlands are ecologically diverse

• Create wildlife corridors

• Link into existing wildlife networks

Amenity/Biodiversity

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• Siting of buildings • Good Housekeeping • Green Roofs • Rainwater harvesting • Filter strips • Disconnecting downpipes

prevention and source control

SuDS Components

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source control

Photo: w

• Rain gardens • Bio-retention areas • Infiltration trenches • Soakaways • Stormwater planters • Permeable paving

SuDS Components

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conveyance

• Swales • Filter drains • Hard channels

SuDS Components

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conveyance

• Rills • Formal channels • Naturalistic constructed streams

SuDS Components

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site controls

• small detention/infiltration basins • small wetlands, urban wetland or ponds • geocellular devices • modular storage systems

SuDS Components

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SuDS Components

larger scale/regional controls

• wetlands • urban wetlands • large scale detention basins • lakes

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LACK OF KNOWLEDGE • of the influence of the background geography of catchments • of the best designed examples • of the water quality impacts • of the benefits of a fully sustainable approach to water management • of unfamiliar methods of construction • of the need for phasing works • about retrofitting SuDS FEAR • of health and safety issues • of potential costs • of adoption issues • of maintenance costs • of long-term management • of land take

What are the perceived challenges?

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• Integrate SuDS at early stage

• Involve and educate all stakeholders

• Agree on adoption and maintenance

• Agree on design criteria and SuDS vision

• Allow SuDS to inform masterplan

• Allow sufficient space for SuDS

• Consider location of buildings

• Retain natural drainage routes

• Reduce hard surfaces

• Create an interlinked hierarchy of SuDS

• Utilise comprehensive pallette of techniques

masterplanning

How can we use SuDS effectively?

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The site

Cribbs Causeway, Bristol

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Hydrology of catchment


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Natural flow of water


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Run-off from hard surfaces


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SuDS Strategies


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Typical Major Road


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Typical domestic road


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Typical detailed area


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Detailed studies

Detention

basin with

permanent

pond

Site control

feature

swales

along

road/source

control

open

channels

open

canal

Conveyance to

regional control

feature


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Typical submission and quality of information

Information in a Flood Risk Assessment

• Pond 1A – a wet pond, in the south west of the site, approx capacity of 9125m3. To receive all runoff.

• Pond 1B – a dry attenuation area to the east of Newland road, approximately capacity of 1740m3. Sized to receive runoff for events with a return period exceeding the 1 in 30 year.

• Area 1C buried attenuation – to be located below the village green, approximate capacity 2430m3. Sized to receive runoff for events with a return period up to the 1 in 30 year.

• Area 1D dry attenuation area – to be located on the village green, approximate capacity of 960m3. Sized to receive runoff for events with a return period exceeding the 1 in 30 year.

• Swales – theses have been assessed but they would need to be considered at the detailed design stage.

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Typical submission and quality of information

FRA – SuDS Strategy

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Priors Park, Oakley

Retrofitting SuDS in Cheltenham

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How do we get to good SuDS design?

• Be supported by planning

• Integration of SuDS at early stage

• Use an interdisciplinary approach to achieve

a common vision

• Involve stakeholders

• Understand the hydrology of the site

• Understand the ecology/flora

• Work with existing features and habitats

and be inspired by the local vernacular

• Create an identity

• Ensure long-term maintenance

• Be brave and try something new

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• Use water as a resource

• Allow water back into the city

• Create visible routes for water

• Deal with flooding locally

• Ensure clean water environment

• Provide habitat and enhance biodiversity

• Use SuDS as a design element

• Create beautiful landscape features

• Deliver quality maintenance and long-term

management

Let’s celebrate water…

…and deliver beautiful sustainable landscapes

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Any questions?

green infrastructure & biodiversity, functional landscapes seminar, sue illman

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