University of Gloucestershire Faculty of Media, Arts & Technology

School of Art & Design

Supervisor: R.Snowdon

Evaluating the feasibility of retrofitting a sustainable urban drainage system into an existing drainage system for cleansing and improving the water quality of an area of suburban Dublin, Ireland.

UNIVERSITY OF GLOUCESTERSHIRE

This thesis is submitted in part fulfilment of the degree of a Masters of Art in Landscape Architecture at the Faculty of Media, Arts & Technology School of Art & Design

By

Fergus Patrick McCarthy

15/10/2014

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To my family and friends

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Title

Evaluating the feasibility of retrofitting a sustainable urban drainage system into an

existing drainage system for cleansing and improving the water quality of an area of

suburban Dublin, Ireland.

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(i) Declaration

This thesis is the product of my own work and does not infringe the ethical principles

set out in the University’s Handbook for Research Ethics: A Handbook of Principles

and Procedures.

Signature of Candidate:.............................................................

Typed name: Fergus Patrick McCarthy

Date:.............................................................

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(i) Declaration .................................................................................................... 4

(ii) List of tables .................................................................................................. 9

(iii) List of figures .............................................................................................. 10

(iv) Glossary of terms and abbreviations ........................................................ 12

(v) Acknowledgements..................................................................................... 15

(vi) Abstract ....................................................................................................... 16

CHAPTER 1. INTRODUCTION .............................................................................. 17

1.1 Introduction ................................................................................................ 17

1.2 Background ................................................................................................ 18

1.3 Rationale for the study ............................................................................... 18

1.4 Context ...................................................................................................... 19

1.4.1 Global context ......................................................................................... 19

1.4.2 European context .................................................................................... 20

1.4.3 Irish national context ................................................................................ 20

1.4.4 Dublin regional context ............................................................................ 21

1.4.5 Dun Laoghaire local context .................................................................... 22

1.5 Scope of the study ..................................................................................... 23

1.5.1 Aims and objectives ................................................................................. 23

1.5.2 Methodology ............................................................................................ 23

1.6 Structure of the thesis ................................................................................ 24

CHAPTER 2. LITERATURE REVIEW .................................................................... 25

2.1. Introduction ................................................................................................ 25

2.2. Urban Drainage ......................................................................................... 25

2.2.1 Sustainability in urban drainage ............................................................... 27

2.2.2 Sustainable Urban Drainage Systems (SUDS) ........................................ 30

2.2.3 Deterrents of SUDS applications ............................................................. 37

2.3 Retrofitting SUDS ....................................................................................... 40

2.3.1 Ageing infrastructure and the need to upgrade and retrofit ...................... 40

2.4 Legislative context for stormwater management ........................................ 48

2.4.1 International legislation relating to SUDS ................................................. 48

2.4.2 European legislation relating to SUDS ..................................................... 49

2.5 Irish legislation on surface water drainage ................................................. 53

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2.5.1 Irish legislative context............................................................................. 53

2.5.2 Irish SUDS design standards & guidance ................................................ 57

2.5.3 Implementation of SUDS to date in Ireland .............................................. 58

2.6 Barriers to the implementation of SUDS in Ireland ..................................... 59

2.7 Summary of main findings for a SUDS retrofit ............................................ 60

CHAPTER 3. CASE STUDIES: MALMÖ AND SHEFFIELD. .................................. 61

3.1. Introduction ................................................................................................ 61

3.2 Augustenborg, Malmo: Introduction ........................................................... 62

3.2.1 Context .................................................................................................... 62

3.2.2 Background- Augustenborg, Malmo......................................................... 64

3.2.3 Developing the integrated retrofit proposal .............................................. 65

3.2.4 Sustainable stormwater legislation .......................................................... 66

3.2.5 Design and implementation of SUDS retrofits in Augustenborg ............... 68

3.2.6 Challenges faced and enabling factors of the SUDS retrofit .................... 70

3.2.7 Stakeholder engagement during the retrofit project ................................. 71

3.2.8 Costs of the SUDS retrofit ....................................................................... 72

3.2.9 Successful factors of the SUDS retrofit .................................................... 72

3.2.10 Missed opportunities .............................................................................. 74

3.3 Manor Fields Park, Sheffield: Introduction .................................................. 75

3.3.1 Drivers and Delivery ................................................................................ 76

3.3.2 Challenges Faced during the SUDS retrofit ............................................. 79

3.3.3 Stakeholder engagement of the SUDS retrofit ......................................... 80

3.3.4 Costs of the project .................................................................................. 80

3.3.5 SUDS retrofit success factors .................................................................. 80

3.3.6 Manor fields missed opportunities ........................................................... 82

3.3.7 SUDS retrofit devices utilised .................................................................. 82

3.4 Summary of the case studies main findings ............................................... 83

3.5 Discussion ................................................................................................. 84

CHAPTER 4. RETROFITTING SUDS: APPLYING RESEARCH MODELS TO THE

STUDY AREA ........................................................................................................ 85

4.1 Introduction ................................................................................................ 85

4.2 Methodology for applying models to Glasthule village, South Dublin .......... 85

4.3 Applying lessons learned to Glasthule village, South Dublin ...................... 86

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4.4 Preparation of the scoping process ............................................................ 87

4.4.1 Establishing the need and drivers for change .......................................... 87

4.4.2 Establishing potential partnerships .......................................................... 89

4.4.3 Early engagement objectives ................................................................... 90

4.4.4 Scope of the retrofit study ........................................................................ 90

4.5 Applying the feasibility study to Glasthule village ....................................... 91

4.5.1. Site selection criteria one ........................................................................ 91

4.5.2 Confirming the needs............................................................................... 99

4.5.3 Opportunities for retrofitting- West Pier Catchment, Dun Laoghaire ....... 100

4.5.4 Matching opportunities with needs ......................................................... 102

4.5.5 Site Selection Matrix- Glasthule village .................................................. 103

4.5.6 Anticipated constraints........................................................................... 104

4.6 Developing SUDS retrofit options ............................................................. 105

4.6.1 Retrofit option planning .......................................................................... 105

4.6.2 Considering space and selecting retrofit measures ................................ 105

4.6.3. Retrofit measures- West Pier catchment:.............................................. 106

4.6.4 Retrofit measures- Glasthule ................................................................. 109

4.7 Appraisal of the SUDS retrofit project....................................................... 112

4.7.1 Assessing the benefits and costs involved in the retrofit project............. 112

4.8 Implementation of SUDS retrofit options .................................................. 113

4.8.1 Planning the retrofit measures ............................................................... 114

4.9 Performance monitoring ........................................................................... 115

4.9.1 Monitoring and evaluating the approach ................................................ 115

4.9.2 Gaining experience ................................................................................ 115

4.9.3 What to monitor in SUDS, what to assess and why? ............................. 116

4.9.4 Collate data and learn through sharing .................................................. 116

CHAPTER 5. CONCLUSIONS AND FUTURE RECOMENDATIONS .................. 117

5.1 Introduction .................................................................................................. 117

5.2 Summary and Conclusions .......................................................................... 117

5.2.1 Retrofitting SUDS to Glasthule .............................................................. 119

5.2.2 Lessons learned from Glasthule village ................................................. 120

5.3 Recommendations in policy and legislation changes ................................... 121

5.3.1 EC Water Framework Directive (WFD) .................................................. 121

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5.4 Discussions and suggestions for further research ........................................ 122

References .......................................................................................................... 124

References- figures ............................................................................................ 135

Bibliography ........................................................................................................ 139

APPENDICES ...................................................................................................... 140

Appendix A: Terminology and Key Definitions ................................................... 141

Appendix B: Vogelwijk, Den Haag: Introduction ................................................. 143

Driver and delivery ......................................................................................... 144

Challenges faced ............................................................................................ 144

Stakeholder engagement ............................................................................... 145

Cost ................................................................................................................ 145

Success Factors ............................................................................................. 145

Missed opportunities....................................................................................... 145

Appendix C: Combined sewers and combined sewer overflow .......................... 146

Appendix D (i): SUDS Designs .......................................................................... 150

Appendix D (ii): SUDS Concepts ....................................................................... 151

Appendix E: Illustrated SUDS concepts ............................................................. 153

Appendix F: SUDS scorecard assessment ........................................................ 158

Appendix G (i): The European Flood Directive 2007/60/EC ............................... 159

Appendix G (ii): Adoption of EU Directives in UK Legislation ............................. 160

Appendix H (i): Historical development of drainage engineering Ireland ............ 162

Appendix I (i): SUDS Guidance in Ireland .......................................................... 164

Appendix J: Developing a Cost Benefit Analysis (CBA) ..................................... 165

Appendix K: Opportunities for SUDS retrofit ...................................................... 166

Appendix L: Overview of projects in Malmö ....................................................... 168

Appendix M (i): Summary of Historical flooding fix map ..................................... 169

Appendix M (ii): Background flooding in Glasthule ......................................... 171

Appendix M: Scorecards carried out .................................................................. 175

Appendix N (i) Emails to Personal Interviews .................................................... 177

Appendix N (ii) Personal Interviews ................................................................... 178

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(ii) List of tables

Table 2.1: Strategies towards sustainable urban drainage ...................................... 29

Table 2.2: Stormwater runoff pollution concentration and land uses ....................... 35

Table 2.3: Pollutants removed in SUDS .................................................................. 36

Table 2.4: Key Frameworks for a SUDS retrofit ...................................................... 60

Table 3.1: Illustration of different solutions mentioned in Figure 3.5 ........................ 69

Table 4.1: Examples of the potential partners or stakeholders ................................ 89

Table 4.2: Linking potential causes with the effects: Source-Pathway-Receptor ..... 99

Table 4.3: Opportunities for retrofitting in Glasthule. ............................................. 101

Table 4.4: Strategies to address problems at the Source-Pathway-Receptor ........ 102

Table 4.5: Scorecard for SUDS assessment ......................................................... 105

Table 5.1: Pollutants SUDS .................................................................................. 150

Table 5.2: Advantages & disadvantages of various SUDS concepts. .................... 151

Table 5.3: Score card assessment utilised for adoption of SUDS retrofits ............. 158

Table 5.4: Key Guidance documents for urban hydrology ..................................... 164

Table 5.5: The main type of SUDS retrofit techniques ........................................... 166

Table 5.6: Description and implementation opportunity for SUDS retrofit .............. 167

Table 5.7: Overview of the described sustainable urban drainage ........................ 168

Table 5.8: Summary of rainfall events ................................................................... 171

Table 5.9: Summary of study areas historic flooding ............................................. 172

Table 5.10: Existing catchment environmental performance ................................. 174

Table 5.11: Scorecard for retrofitting West Pier catchment, Dun Laoghaire .......... 175

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(iii) List of figures

Figure 1.1: Contextual Map indicating the location of Glasthule village ................... 22

Figure 2.1: SUDS Tree-ring Model .......................................................................... 30

Figure 2.2: Illustration of the hydrological effect of urbanisation .............................. 32

Figure 2.3: The Treatment Train ............................................................................. 36

Figure 2.4: Bar chart of perceived barriers to SUDS application ............................. 38

Figure 2.5: A framework for retrofitting. ................................................................... 43

Figure 2.6: The four hierarchies of the retrofit SUDS decision-making framework ... 45

Figure 2.7: Surface water bodies currently failing good status/nutrient conditions ... 50

Figure 2.8: Good Status objectives for surface waters ............................................ 51

Figure 2.9: The serial approach to Stormwater management in Ireland .................. 54

Figure 2.10: Adopted structural methods for attenuating stormwater ...................... 55

Figure 2.11: Understanding of different techniques in the management train

approach to stormwater management. .................................................................... 56

Figure 2.12: Summary of additional information ...................................................... 58

Figure 2.13: Perceived deterrents to the implementation of SUDS in Ireland. ......... 59

Figure 3.1: Map of Sweden ..................................................................................... 62

Figure 3.2: Green areas-owned by Municipality. ..................................................... 64

Figure 3.3: Examples of values considered ............................................................. 65

Figure 3.4: Models once applied and currently applied to Malmo. ........................... 67

Figure 3.5: Overview of the stormwater system in Augustenborg ............................ 69

Figure 3.6: Manor Fields Park Contextual Map ....................................................... 75

Figure 3.7: Plan showing basin configuration .......................................................... 77

Figure 3.8: A parallel approach of interactive implementation of SUDS retrofits ...... 83

Figure 4.1: A framework for retrofitting. ................................................................... 86

Figure 4.6: Flood events in Glasthule village ........................................................... 88

Figure 4.7: Scope of retrofitting to the West pier catchment .................................... 90

Figure 4.8: Site Preference for SUDS ..................................................................... 91

Figure 4.9: Map of catchment area: Sub catchments .............................................. 92

Figure 4.10.1: Map of catchment area (Taylor, 1816). ............................................. 93

Figure 4.10.2: Map of catchment area 1937. ........................................................... 94

Figure 4.11: Interpolation of pre-development open watercourses .......................... 95

Figure 4.12: Railway line during groundwater flooding ............................................ 96

Figure 4.13: Separate drainage & undeveloped areas and open space .................. 97

Figure 4.14.1: The plate Castlepar Rd. ................................................................... 98

Figure 4.14.2: Key Drainage Infrastructure ............................................................. 98

Figure 4.15: Opportunities for retrofitting SUDS .................................................... 100

Figure 4.16: Breakdown of landtake in Glasthule .................................................. 103

Figure 4.17: Proposed retrofit for Sallyglen Road .................................................. 107

Figure 4.18.1: Proposed constructed wetland for Dalkey Quarry .......................... 106

Figure 4.18.2: Proposed retrofit for St. Catharine’s Road ...................................... 108

Figure 4.18.3: Proposed retrofit for Glasthule village............................................. 109

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Figure 4.19: Key synergies and implementation .................................................... 114

Figure 5.1: Vogelwijk Site plan .............................................................................. 143

Figure 5.2.1: Combined Sewer (schematic plan) ................................................... 146

Figure 5.2.2: CSO inflow and outflow .................................................................... 147

Figure 5.3: Examples of different design standards .............................................. 149

Figure 5.4.1: Downpipe Disconnection .................................................................. 153

Figure 5.4.2: Rain garden ..................................................................................... 154

Figure 5.4.3: Attenuation pond .............................................................................. 155

Figure 5.4.4: Permeable Pavements ..................................................................... 155

Figure 5.4.5: Swales and soakaways .................................................................... 156

Figure 5.4.6: Detention Basin ................................................................................ 157

Figure 5.4.7: Wetland ............................................................................................ 157

Figure 5.5: Cost-Benefit analysis of SUDS scheme- model assumptions .............. 165

Figure 5.6: Locations of historical flooding in the West Pier Catchment ................ 169

Figure 5.7: Pattern of previous flooding in Glasthule village .................................. 173

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(iv) Glossary of terms and abbreviations

Attenuation - Reduction of peak flow and increased duration of a flow event.

BMP - A Best Management Practice (BMP) as defined by the U.S. Clean

Water Act is a technique, process, activity, or structure used to reduce

the pollutant content of a storm water discharge.

Catchment - The area contributing surface water flow to a point on a drainage or

river system.

CIARIA - Engineering Company in the UK which is the leader in SUDS

innovations.

CSO - Combined Sewer Overflow. The discharging, during storm events, of

untreated waste water from combined sewers into streams and Rivers

CSS - Combined Sewer System

DDC - Dublin Drainage Consultancy

DLRCC - Dun Laoghaire Rathdown County Council. One of the 31 local

authorities in Ireland

DECLG - Department of Environment, Community and Local Government. An

Irish State Department in charge of environment, housing,

infrastructure, physical and spatial planning.

DWF - Dry weather flow.

EA - Environmental Agency

EEB - European Environmental Bureau. The European Environmental

Bureau (EEB) is a federation of over 140 environmental citizens’

organisations based in most EU Member States.

GDSDS - Greater Dublin Strategic Drainage Study

GES - GES of surface water bodies is described with biological, hydro

morphological and general physico-chemical quality elements. GES is

achieved when the biological quality elements (e.g. composition and

abundance of fish or benthic invertebrate fauna) and general physico-

chemical quality elements (e.g. oxygenation or nutrient condition) are

only slightly deviating from a situation where there are no or only

minimal human impacts (EEB, 2010, p16).

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Greenfield

Runoff - The rate of runoff that would occur from an undeveloped site

Irish Water - Is a state owned company, where under the Water Services Acts

2007-2013 brings the water services of 31 local authorities together

under one national services provider (Irish water, 2014)

OPW - Office of Public Works (Ireland)

Pervious

Pavement - Permeable hard standing, with subsurface storage and/or infiltration

Retrofit SUDS - The use of SUDS to replace or augment conventional stormwater

drainage within a developed catchment.

SA - Sanitary Authority SAAR - Standard average annual rainfall

Source

Control - Control of run-off at or near its source, e.g. rainfall on a car park.

SSO - Stormwater sewer outfall

Storm or Surface water runoff - Runoff from roofs and paved (impermeable) surfaces

SUDS - Sustainable Urban Drainage System

SWMM - Surface water management measures

SNIFFER - Scotland and Northern Ireland forum for environmental research

SS - Suspended solids: un-dissolved particles in a liquid

SUDS - Sustainable Drainage Systems – a sequence of management

practices and control structures designed to reduce, treat and

attenuate surface water runoff (CIRIA, 2001)

Treatment Volume (Vt) -The volume of surface runoff (first flush volume) TTS - Total suspended solids

UID - Unsatisfactory Intermittent Discharge

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WA - Water Authority

WFD - European Water Framework Directive (2000/60/EC)

WSUD - Water Sensitive Urban Design

WTP - Wastewater Treatment Plant

VOC’s - Volatile Organic Compounds

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(v) Acknowledgements

I wish to thank the following people most sincerely for all their help and support in

helping me research and write this thesis:

- the lecturers in the University of Gloucestershire and in particular Mr. Booth. I

would also like to pay special thanks to my supervisor Mr. Snowdon for his expert

guidance and encouragement.

- my fellow participants on the MA and the former students on the programme for

their work and insights made available through the reference section of the

Universities library.

- all the interviewees who have contributed to and participated in this research, in

particular Kees Hufen, Fiona Craven, John Collins, Louise Lundberg, Marianne

Beckmann and especially Ewald Oude Luttikhuis.

- to my friend Mr. Finbarr McIntyre for his support, guidance and above all keeping

me focused and motivated on this challenging journey. It has been a privilege.

- I would like to thank my family and friends for all their support and help throughout

the last five years of study.

- Finally, I would like to send my gratitude to Charlene Shortall. You have given me

lots of encouragement in the last couple of months. I look forward to spending

more time with you in the future.

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(vi) Abstract

Sustainable urban drainage systems (SUDS) have been developed as a strategy of

drainage that implements a process of natural treatment through a variety of

techniques to control surface water runoff in urban catchments. Typically, SUDS

technologies involve local filtration, storage and stormwater re-use devices. SUDS

were developed as a way to tackle the problems associated with urbanisation e.g.

flooding, loss of green spaces and biodiversity. As Europe has grown significantly

over the last century it has witnessed the affects of urbanisation, with more than 213

major extreme flood events recorded and major degradation to water across

continent. In an attempt to fight these affects, the European Commission has

implemented a number of umbrella policies that apply to all Member States. The

European Water Framework (2000/60/EC) or WFD is the most pertinent policy that

applies to urban waters. Under the WFD all Member States are required to set out

objectives for achieving ‘good ecological status’ by 2015.

In response to European legislation, Ireland has implemented the Greater Dublin

Strategic Drainage Study (DDC, 2005) (GDSDS). The GDSDS requires all new

developments to implement a form of SUDS to restrict outflows to greenfield values

prior to development. It is clear that Ireland will not meet European objectives under

the current policies and more needs to be done. Glasthule village, is a prime

example of a catchment of South Dublin that has suffered from severe flooding and

combined sewer overflow (CSO) spills over the years.

The research applies lessons learned from the literature review and 3 best practice

examples of SUDS retrofits and applies them to Glasthule village. In order to achieve

a successful SUDS retrofit a model was used to determine the most suitable areas to

retrofit. The retrofit measures use an alternative system of drainage enhancement

that has not yet been used in the area to date. The SUDS retrofit in Glasthule was

maximised through engaging with a best practice framework in order to maximise

key synergies of practitioners in the field SUDS. The study concludes with a

recommendation of key changes to would encourage the uptake of retrofitting SUDS

in Ireland.

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CHAPTER 1. INTRODUCTION

“Water is a basic human need and a key component of development - it is a

fundamental resource for food production as well as for enhancing social well-being

and providing for economic growth. It is also the lifeblood of the environment”.

-Kofi Annan, 2000

1.1 Introduction

“Swimming bans were introduced across 13 of Dublin’s beaches. Tests showed poor microbiological quality. Warnings are that swimming in the sea may cause illness. The ban was due to ‘storm water overflow’ and follows the failure of sewage pumping stations due to heavy rain”

(Carbery, 2014).

This research study explores the issues of retrofitting Sustainable urban drainage

systems (SUDS) in Glasthule village, south Dublin to achieve combined sewer

overflows (CSO).

The chapter opens by providing a background to CSO/flooding problems in Ireland

and a context to retrofitting. By doing so, it is intended to highlight how SUDS

retrofits can have a positive impact on stormwater drainage. Furthermore, the

opening section will highlight the different ways in which SUDS can be applied and

the attitude of professionals involved in SUDS in Ireland.

Whilst it is important to focus on best practice from international experience of how

SUDS retrofits are applied, the different variations on these procedures need to be

put into the local context. This will allow understanding and appreciation of the

current situation in Glasthule Village to find out how the use of SUDS retrofits

impacts on stormwater drainage. This structure will highlight the significant findings

and provide summaries of research collected and so thus inform best practices

models to Glasthule villages. This involves investigating patterns of usage,

considering practitioners perspectives on the use of technology and looking at ways

in which to encourage the use of SUDS retrofits. With the growing use of SUDS by

practitioners in Ireland, there are many issues which affect their adoption, including

the level of technological understanding, land ownership, support through guidance,

experience necessary and cost.

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1.2 Background

Storm/surface runoff is water that is conveyed by gravity that naturally saturates into

soils that flow into ground or receiving waters (Butler, 2011). For permeable

surfaces, precipitation must exceed the infiltration rate; soil saturation must take

place before runoff will occur (Strom et al., 2012). Hennelly (2005) adds that polluted

surface water is cleansed through filtration; water filters through soil at a slow rate

and holds onto pollutants via bacteria. Impervious surfaces react in the opposite

manner, thus creating runoff. Additionally, Apostolaki (2009) argues that heavily

urbanised areas suffer concurrently with severe pluvial flooding i.e. Dublin.

In urban areas development of stormwater drainage is based on centralised,

structural approaches relying on conveyance and retention, including storm drains,

gutters, channels and combined sewers that carry both wastewater and stormwater

in a single pipe to the nearest water body (Porse, 2013; Butler et al., 2011). Storm

(2012), highlights the interesting point of how stormwater management has long

recognised the environmental threats and degradation of watercourses and still

sanitary authorities (SA) still implement the upgraded versions of the same system.

1.3 Rationale for the study

There are two overarching factors which influenced the author to undertake this

study:

The EC Water Framework Directive (2000/60/EC) (WFD) requires all Member States

to protect and improve their water. Objectives are set out at a European level in an

effort to achieve ‘good ecological status’ (GES) by 2015, 2021 and 2027. The EC

outline that water must be improved by a catchment based approach. By current

standards in drainage, Ireland’s water will not meet the 2015 target (EA, 2012).

Research carried out in Dublin; found that 70% of water in wastewater stations were

heavily polluted (DDC, 2005).

Hennelly (2005) argues, that Ireland needs a new direction in the way it manages its

water. The Irish approach to drainage, tackles stormwater and wastewater problems

with outdated techniques. Glasthule village is a prime example of these traditional

approaches. To achieve targets set out by the European Framework Directive the

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study will utilise Glasthule village as an example of how retrofitting SUDS can be

applied to improve water quality. Secondly, Dublin has outgrown its sewerage

infrastructure (Kellagher et al., 2008). Little has changed in urban drainage over the

last decade, even as Dublin grew rapidly during the 1990’s. This has resulted in

exacerbated pressure on the city’s sewage infrastructure. Like many local suburbs

across Dublin, the quality of water has been under scrutiny for many years in Dun

Laoghaire (DLRCC, 1995).

A study by RPS (2009) found, that a SUDS retrofit was unattainable for Glasthule

village and its surrounding catchment. Instead, it was recognised that an upgrade of

traditional measures would be more feasible, due to the built up nature of the area.

However, this approach to drainage is no longer recognised as sustainable.

Retrofitting SUDS augments existing urban drainage that is necessary for

sustainable growth (Stovin, 2009). The study will hypothesis through research and

best practice examples that implementing SUDS retrofits is applicable to the majority

contexts, regardless of density.

1.4 Context

The stormwater management context of which this study is set is intertwined within a

complex context of urban water services, infrastructure and physical, social and

political settings (Ashley et al., 2003). To this end the research context will be guided

by Global, European, National, Regional and Local.

1.4.1 Global context

On a global level, pressures created by the world’s growing population and

economy, combined with the impacts of climate change, are making water scarcity a

reality in many parts of the world. In just twenty years, global demand for water will

be 40% higher than it is today, and more than 50% higher in most rapidly developing

countries. By 2030 over a third of the world population will be living in river basins

that will have to cope with significant water stress (EA, 2012).

Historic rates of supply expansion and efficiency improvements will not be enough to

close this ‘water gap’ and further and stronger measures will be required. Such

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efforts must focus on a mix of solutions including focusing on technical

improvements, increasing supply, improving water productivity and examining

underlying economic activities. This increasingly critical issue of global water scarcity

will require transformation of the global water sector towards long term sustainability

to tackle the gap between supply and demand (DECLG, 2012).

1.4.2 European context

Water scarcity is defined as water demand exceeding the supply of water resource

and according to DECLG (2012). It was estimated in 2007 that 11% of European

citizens and 17% land take were affected this. Europe is fighting a battle on all

fronts, areas of mass drought (costing up to €100billion in the past thirty years).

European countries invest more than €5billion in flood mitigation, elevation and

drainage network improvements yearly according to Sægrov (2004).The economic

analysis does not stress the toll on human life, habitats and Europe’s ecology. Of

particular interest to this study is the international recognition of retrofitting SUDS as

a viable rehabilitation option for sustainable stormwater management.

1.4.3 Irish national context

At an Irish national level: Ireland is experiencing major changes in the methods of

managing its water, with the reorganisation of the water industry. The supply of water

is funded by EU/IMF/ECB and has been privatised. Regulatory functions that have

up to now been carried out internally, like water investment and maintenance will

move to a new organisation: Irish Water (DECLG, 2012, p3).Irish water intends to

improve water quality, water service, increase the cost efficiency associated with

water provision and address water consumption and conservation (DECLG, 2012).

In 2010 water services (supply, waste and surface management) cost €1.2 billion,

of which operational costs amounted to some €715 million, with capital expenditure

of over €500 million. Ireland is currently the only country in Europe not to pay for

water use.

This set to change as the Irish government feel the current model of water provision

is simply not sustainable (DECLG, 2012).In the UK sustainable SUDS techniques

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are gaining ground within the national planning agenda, however their role within the

Irish Planning framework has only recently become established (O’Sullivan et al.,

2011). SUD systems adoption have continuously been supported by a range of

private and public sector organisations that have contributed to the funding of SUDS

analysis. Although, many practitioners are aware of the benefit of SUDS studies

indicates that their use for many reasons remains less popular (O’Sullivan et al.,

2011). As a result, flood protection in Ireland is similar to other countries reactive not

active; cities are building ever higher walls and radically straightening and clearing

rivers, to rush water hastily to sea (Carrington, 2014).

1.4.4 Dublin regional context

In accordance with the WFD local authorities in Dublin released the Greater Dublin

Drainage Study 2005 (GDSDS), which made it mandatory for all new developments

in Ireland to adopt SUDS. Unlike conventional drainage SUDS aims to restore the

artificial imbalance by utilising natural resources to replicate the natural catchments

process and allow rainfall to infiltrate, attenuate; essentially slowing the conveyance

rate.

This has influenced Ireland in that stormwater is now primarily attenuated through

hard solutions, such as hyrdobrakes or similar water storage devices that reduced

water rates via a control structure to greenfield values (Doyle et al., 2003). These

impractical solutions fail to meet the demands for stormwater quality improvement

and often culminate in the construction of large storage tanks where water is

discharges slowly, as appose to using water as a resource to improve amenity

space, biodiversity and quality of life.

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1.4.5 Dun Laoghaire local context

Glasthule village has been chosen as the study area, as it provides an interesting

range of conventional drainage problems in Ireland. This relates to the areas pluvial

flooding, combined sewer overflows and unsatisfactory intermittent discharge (UID)

during heavy rainfall events typical of stormwater problems in Ireland. The village sits

in a basin between two pumping stations, Bulloch Harbour to the East and the West

Pier Pumping Station to the West as illustrated on Figure 1.1.

Figure 1.1: Contextual Map indicating the location of Glasthule village

23

1.5 Scope of the study

This section covers the aims, objectives and relevance of this research study.

1.5.1 Aims and objectives

This study investigates the benefits of applying SUDS retrofit as a flood mitigatory

strategy for conventional urban drainage problems. The primary aim is to create an

alternative solution to poor drainage problems that result in CSO spills and flood risk

in Glasthule village (West Pier Drainage Catchment). In order to design a

Sustainable Urban Drainage System that can achieve the aims set out above the

following actions were carried out and are described in the study:

Identify current EU and Irish legislation regarding SUDS.

Identify current guidance for SUDS adoption in Ireland.

Outline the criteria of SUDS devices that are required for the implementation

of drainage improvements in the study area of Glasthule.

Consider some of the cost benefits of retrofitting SUDS over a conventional

drainage system

Identify factors that may restrict or prevent the implementation of SUDS and

factors affecting the selection of SUDS retrofit measures

Identify whether hard (underground storage) or soft measures (ponds, swales

etc) are appropriate contextually to the study area.

1.5.2 Methodology

A qualitative research method was applied to provide the necessary information for

the evaluation of retrofitting SUDS in suburban Dublin through face-to-face

interviews with practitioners. The research method is highly dependent on case

studies which interview topics were based upon, enabling the interview to primarily

focus on case study facts, behaviour and their beliefs or attitudes. The interviews

were conducted in a semi-structured format to permit the omission and/or addition of

questions and the modification of the lines of inquiry when appropriate. The

interviewer also exploited the use of supplementary documentary evidence and

direct observations.

24

The qualitative interviews relate to case studies involving SUDS retrofit schemes at

Augustenborg, Malmö, Sweden; Manor Fields District Park, Sheffield, UK. A further

case study of Vogelwijk, Den Haag, the Netherlands was examined and can be

found in Appendix B. The case studies demonstrate practical opportunities for

reducing or resolving the flooding problems with ‘quick fix’ engineered solutions,

retrofit options, and long-term ‘planning-based’ remedial measures. These same

issues are very relevant to the Irish study area containing stormwater flooding

problems.

1.6 Structure of the thesis

The following chapters of the study are described briefly below:

The second chapter describes the results of a detailed examination and review of all

the relevant and current international documentation regarding SUDS in Ireland.

The third chapter investigates three case studies that have successfully implemented

SUDS retrofit to treat stormwater runoff. The main objective is to evaluate the

potential for applying knowledge gained from case studies and apply them to the

study area to improve water quality and hydraulic performance.

The fourth chapter evaluates the feasibility and value of retrofitting a sustainable

urban drainage system (SUDS) in the chosen study area of Glasthule village. The

most beneficial method of retrofitting SUDS through planning, design and site

management is identified and described.

In conclusion, the final chapter summarises the research that was undertaken in this

study, draws a number of key conclusions and highlights the potential for further

research.

(See Appendix A for terminology and key definitions)

25

CHAPTER 2. LITERATURE REVIEW

“Research is systematic, critical and self-critical enquiry which aims to

contribute to the advancement of knowledge and wisdom”

-Bassey, 1999, p.38

2.1. Introduction

This literature review aims to look at readings in the area of changing attitudes to the

use of technology in stormwater management and explore evolving technologies in

urban drainage. The research will also aim to highlight literature on issues arising

from the use of SUDS technology and retrofitting SUDS in Ireland. A review of

international guidance on stormwater drainage will be recognised in order to provide

a catalyst for change in the way Ireland manages it water.

2.2. Urban Drainage

The intrinsic nature of human activity is the production of waste (Tchobanoglous et

al., 2004). From the standpoint of urban water, people in urban landscapes impact

on water through two forms, highlighted by Butler (2011). Firstly by abstraction of

water from its natural cycle essential for life; used for consuming, bathing and

industrial processes. The second form is precipitation in an urban area. A

combination of interactions result in two types of water conveyed through urban

areas, distinctive by quantity and quality. Such as ‘stormwater’ or ‘wastewater’, both

have the potential to flow through piped singular systems (combined Sewers) or in a

separate drainage system (Cordero, 2012). It is essential for the protection of public,

environment, economical and political health that both types of liquid waste are

removed in a clean and nuisance-free manner from the source of generation, where

it can be subsequently treated or re-used (Tchobanoglous et al., 2004).

Pitt (2008) indentifies the intensification of storm events coupled with the onset of

climate change extreme scenarios are forecast far outweighing what has previously

been predicted. Paradoxically, wastewater and stormwater generation is increasing

at an exponential rate, due to climate and demographic change, life expectation and

a rapid population growth and urbanisation (Lundqvist, 2011). Subsequently, there

are damaging trends that governments tend to cut drainage rehabilitation of financial

funding, year-on-year, for funding of construction and operations urban drainage

26

(Cordero, 2012). Awareness is beginning to gain ground in the mainstream that

highlights existing infrastructures consistent failure to cope when confronted with

extreme weather events (Illman, 2014).

In addition, there is pressing need to adopt a different approach to urban drainage;

one that moves away from the focus of the short term solutions of traditional

drainage that has dominated the last century (LI, 2013). Essentially, future cities

must gain multi-benefits from drainage systems that can be flexible and easily

adaptable to future uncertainties (Peters et al., 2010). According to Gersonius

(2011), these changes must occur across all administrations of standards,

performance as well as the external drivers and surface water management assets.

Natural integrated catchment management approaches are increasingly gaining

traction in the public sphere. For example, current studies on urban drainage

promote the services of natural un-piped drainage. It provides countless benefits in

urban drainage while creating synergistic opportunities that can contribute to human

well-being and future growth of cities (Veerbeek et al., 2010).

The UK is similar to Ireland, in that the main reasons for adoption of SUDS is

through new development (Stovin et al., 2007). However, the need for SUDS to

protect natural water quality, water cycles and mitigate diffuse pollution and flooding

remain an intricate problem. Consequently SUDS is under exploited as an implement

to manage stormwater mirrored by Pitt (2008)

“New properties make up only around 1 per cent of the total property stock every

year in the UK” (p76).

Swan (2003) demonstrates that existing drainage rehabilitation through retrofitting

SUDS is a cost-effective approach for improving stormwater management in urban

catchments. Illman (2014) President of the Landscape Institute argues, that there is

a need to overhaul existing sewer infrastructure by retrofitting SUDS to mitigate

against further flooding and climate change. However, Gordon- Walker (2007)

argues that a complete overhaul of infrastructure is challenged by perceived barriers

such as responsibility for ownership and maintenance. These barriers are highly

27

influential for cost-benefits and general uptake of SUDS measures and will be

examined in further detail.

(Please see Appendix C for details on conventional drainage systems)

2.2.1 Sustainability in urban drainage

The concept of sustaining the long term future of the World’s environment was

introduced by the UNCED Rio Declaration, Agenda 21 (1992). This is based on the

integrated approach of combining technical, economic and social aspects of

development. Sustainable drainage is high on the consensus of the global agenda at

present (O’Sullivan et al., 2011).

Advocates of sustainability imply varying aims in stormwater management. In a

review undertaken by Shaw (2003) indentifies the altering adoption over the last

decade. He further synthesises that sustainable objectives have focused on

ecological values ranging to social and technical issues that address stakeholder

acceptance, affordability and appropriateness. Climate change adds the dynamic of

‘flexibility to the debate on urban infrastructure that future systems can adjust to the

external drivers (Litman, 2010, Stovin et al., 2009). Furthermore, stormwater

management upgrades need to be resilient to future uncertainties if they are to be

considered truly sustainable (Shaw, 2003).

In addition the Bruntland Report (1987) identifies sustainable development’ as;

“...meeting the needs of the present without compromising the needs of future

generations without compromising the ability of future generations to meet their own

needs” (WCED, 1987). Which has been adapted to urban water systems, according

to ASCE/UNESCO (1998) (Butler 596) Sustainable water systems are; “Those

systems designed and managed fully to contribute to the objectives of society, now

and in the future, while maintaining their ecological, environmental and hydrological

integrity”.

Butler (2011) divulges, that although the principles of sustainable development have

been accepted, is not clear how to precisely put them into practice. Butler

emphasises the literature of Butler and Parkinson (1997) where they capture

28

objectives of ‘sustainable urban drainage’ proposed in the following list in order of

priority:

1 Maintenance of an effective public health barrier

2 Avoidance of local or distant flooding

3 Avoidance of local or distant degradation/pollution of the environment (water,

soil, materials)

4 Minimisation of the utilisation of natural resources (water, nutrients,

energy/carbon, materials)

5 Reliability in the long term and adaptability of future (as yet unknown)

requirements.

Butler (2011) further expands the list to include the broader requirements of:

Community affordability

Social acceptability

He also emphasised the challenge in conveying a viable solution that encapsulates a

constantly flexible model that is unaffected by unpredictable changes in condition

and hygienically acceptable. Butler & Parkinson (1997) further recccomend three

fundamental strategies that should be applied to successfully achieve multiple

benefits:

Reduction in the reliance on water as transport medium for waste

Avoidance of mixing industrial wastes with domestic wastewater

Avoidance of mixing storm runoff with wastewater

Shaw (2003) and Laursen (1997) surmise, that it is not possible to implement a

completely sustainable urban drainage system when retrofitting, as it would involve

the unrealistic overhaul and urban area. This unrealistic upgrade relates to the

resources economically, technically and logistically that would be associated with

such a change. Mirrored by Butler (2011) commenting, that it is unlikely that large

scale replacement of existing systems is likely to be sustainable. Instead a rational

perspective of incremental upgrades to ageing drainage systems. This would avoid

the inherent problems of large scale changes to urban infrastructure. Several authors

29

advocate this approach to achieve a truly sustainable water system (Butler, 1997;

Shaw, 2003, Butler, 2011). This is mirrored by Ashley (2011) when writing:

“Despite many publications claiming SUDS or BMPs are (by definition) more

‘sustainable’ than piped systems; this depends entirely on local conditions and the

wider catchment context and it is not possible to define ‘a priori’ that any one system

is more or less sustainable than the other without context; especially for retrofitting

which is invariably more complicated than new build” (p3).

Additionally, Swan and Stovin (2002) hypothesise that retrofit SUDS are more likely

to involve so called “hybrid schemes”, or combinations of conventional and SUDS

systems. The strategies and their potential advantages and disadvantages are

summarised on the table 2.1 below; (Adapted from Butler, 2011)

Table 2.1: Strategies towards sustainable urban drainage

Component of water

Problems Proposed Strategies Potential Advantage Potential Disadvantage

Carriage Water

Unnecessary water consumption

Dilution of wastes

Requires expensive end-of-pipe treatment

Introduce water conservation/ efficiency techniques

Reuse water

Seek alternative means of waste conveyance

Conserve Water resources

Improves efficiency of treatment processes

Increases possibility of sedimentation in sewers

Health hazard associated with water reuse

Industrial Water

Disrupts conventional treatment

Biological increases cost of wastewater treatment

Causes accumulation of toxic chemicals in the environment

Renders organic wastes unsuitable for agricultural reuse

Remove from domestic waste streams

Pre-treat, reduce concentration of problematic chemicals

Promote alternative industrial processes using biodegradable substances

Improves treatability of wastewaters

Improves quality of effluents and sludges

Reduces environmental damage

Saves Costs associated with reuse of recovered chemicals

Costs associated with implementing new practice

Lack of monitoring facilities

May promote illicit waste disposal

Stormwater Requires large and expensive sewerage systems

Transient flows disrupt treatment process

Discharge from flows cause environmental damage

Causes floods

Utilise overland drainage patterns

Store and use stormwater as a water resource

Provide infiltration ponds, percolation basins and permeable pavements

Promote ecologically sensitive engineering, constructed Wetlands

Reduces pollution from overflows

Improves efficiency of treatment

Recharges groundwater

Reduces demand for potable water

Reduces hydraulic capacity of conduits

Decentralised facilities harder to monitor

Increases space requirements

Risk of groundwater contamination

30

2.2.2 Sustainable Urban Drainage Systems (SUDS)

Sustainable Urban Drainage Systems (SUDS) have been developed as a strategy of

drainage which implements a system of natural treatment processes through a

variety of techniques to control surface water runoff in urban catchments (Woods-

Ballard et al., 2007). SUDS are defined by CIRIA (2001) as;

“…a sequence of management practices and control structures designed to

drain surface water in a more sustainable fashion than some conventional

techniques” (p4).

Apostolaki (2009) adds to this definition by stating that:

“SUDS provide a more sustainable way of draining surface water, with special

emphasis on amenity, biodiversity and social runoff” (2)

Placed at the centre of the ‘Three-ring model’; SUDS are designed to function with

multiple benefits to urban drainage through three aspects in Figure 2.1 (Woods-

Ballard et al., 2007). The model derives from the ‘sustainable development model’

based on social, environmental and economical goals of sustainable development

that encompass the target areas of sustainable urban drainage (Jefferies et al.,

2003). To provide a context the tri-ring model; quality, quantity and amenity on the

diagram (Figure 2.1), illustrates how SUDS is related to the three theories equally

(Cordero, 2012).

Figure 2.1: SUDS Tree-ring Model

(p15)

31

The model above conveys the complex, collaborative, reciprocal relationship

between the components that generate SUDS. The integrated approach of

hydrological performance, water quality and amenity creation is managed equally in

the creation of a sustainable flood risk management strategy each of which is

discussed below:

(a) Amenity

The idea of amenity sparks connotations of nature, biodiversity preservation,

aesthetics, recreation and leisure (Apostolaki, 2009, p12). The term Amenity is a

derivative from the Latin word for pleasant ‘amoenus’ and suggests a desirable place

with everyday uses (Oxford, 2014). In an effort to define amenity, Apostolaki, (2009,

p13) highlights the Resource Management Act of New Zealand (1991) when it

states:

“Amenity values are those natural or physical qualities and characteristics of

an area that contribute to people’s appreciation of its pleasantness, aesthetic

coherence, and cultural and recreational attributes”

Such definitions relate to the idea that if an area is to be regarded as ‘high amenity

value; then it needs to correlate between people and nature (Taylor, 1998,

Apostolaki, 2009). In the past, and to some extent, modern practices of urban

drainage have contributed to the perspective of a city biota devoid of nature

(Karvonen, 2011; p14). As discussed in previous chapters; under the current

paradigm of urbanisation; combined surfaces and rapid conveyance of stormwater

management amplify the divide between city and nature (Karvonen, 2011; p14).

There is now a belief shared from environmentalists, politicians and the public

attitudes that a healthy society can only exist within a healthy environment and vice

versa (Apostolaki, 12). This was evident in 19th century Britain when public parks

were developed as a means of promoting public health, with the intent to reduce

disease, crime and social discrimination (Hough, 11, 2006). The creation of natural

environments within the urban landscape is often synonymous with introducing

beauty in a city and improving living conditions of local residents. In the fabricated

city, it is difficult to determine what is truly “natural” and achieving a natural

32

landscape with amenity value is underpinned by preserving and/or introducing

biodiversity to re-create the perception of a natural landscape (Apostolaki,2009; 13).

(b)Quantity

In urban areas, drainage problems that effect human affairs can be inevitably

associated with precipitation. High levels of rainfall or the rapid thawing of snow can

create peak flow conditions and together with an overloaded sewer system can form

the basis for flooding (Shaw, 2011, 155).

Figure 2.2: Illustration of the hydrological effect of urbanisation

(CIRIA, 2014)

Drainage stressors are aggravated when artificial drainage systems have insufficient

capacity to manage peak flow conditions caused by surplus water, intensity and

excess ratios of impermeable surfaces and the hydrological connection with the

landscape is fragmented or nonexistent, providing little buffering protection, as

shown on Figure 2.2 (WSP, 2011 & Novotny, 2010, p2). Traditional solutions for

these problems could include upgrading CSO structures, sewer pipes or storage

facilities, to detain or divert excessive flows once they are within the sewer system,

but they do not tackle the important issue of water at source point.

33

Figure 2.2 illustrates the hydrological effect of urbanisation on surface peak flow

surcharges, which SUDS are designated to offset. Peak charges can be accelerated

by two-five times the predevelopment rate resulting in a high chance of pluvial

flooding and a rise in CSOs (Storm, 148, 2013).

Surface water flooding occurs during short heavy rainfall events and is often

convective in nature, is therefore extremely difficult to predict; unlike catchments with

green space where response time is prolonged (MWH, 2014). Distinctions between

SUDS measures and conventional drainage techniques to problems are that SUDS

emphasise a source point control, rather than upgrade to divert excess flows (Shaw,

2003).

SEPA (2013) argue that continual upgrading of traditional drainage infrastructure is

unsustainable, impractical and not resilient to climate change. The logic of efficient

conveyance of urban run-off is at odds with modern calls for environmental

protection as referred to by Karvonen (2011, p15) in the writing of landscape theorist

Hough (2006) when he states:

“The benefits of well-drained streets and civic spaces are paid for by the costs

of eroded stream banks, flooding, impaired water quality and the

disappearance of aquatic life” (p12).

The aim of SUDS is to replicate the hydrological process which occurs in a natural

catchment, with the aim to reduce run-off and increase infiltration, water storage and

release run-off through evapo-transpiration and percolation (Hamill, 2011, p 554). A

flexible approach is implemented by SUDS which utilise a series of techniques

formed as part of a treatment train, designed to meet a contextual constraints

(Wilson, 2004, p29).

The main effects of SUDS on urban water quantity is summarised below:

34

1) Lower peak flows to watercourses or sewers, thereby reducing the risk of

flooding downstream.

2) Reduced volumes and frequency of water flowing directly from developed

sites to watercourses or sewers, to replicate natural land drainage, therefore

reducing flood risk.

3) A reduction in the number of combined sewer overflow levels of unsatisfactory

discharge rates (UID) into watercourses.

4) Replicate natural drainage patterns so that changes to base flows are

minimised.

5) Increased base flow to watercourses through slow release of water.

(c) Quality

In addition to water quantity problems associated with the altered hydrology within

urban landscapes there are issues relating to water quality (Hamill, 2011). Water is

the universal solvent and for this reason, neither rainfall nor stormwater can be

assumed as ‘pure’ (Butler, 2011).

Research has shown that surface/storm water can be heavily contaminated with a

complex mixture of organic and inorganic substances that are associated with

transport, commercial and industrial practices (Butler, 2011). Materials leech into

groundwater through atmospheric pollutants or as a result of erosion from urban

surfaces and stormwater can be just as polluted as wastewater. Levels of pollutants

are highly variable and dependable on a catchment-by-catchment basis.

Butler (2011) adds, that the solvent nature of stormwater is innate in its variable

characteristics from catchment sources which include emissions, corrosion and

abrasion; building and road erosion; bird and animal faeces; street litter deposits,

fallen leaves and grass residue; and spills. Furthermore, Austin (2014) highlights

how stormwater has a constant concentration such as those shown on Table 2.1

below.

35

Table 2.2: Stormwater runoff pollution concentration and land uses

Contaminant TSS

a

E.coli

b

TN

a

P a Copper

c

Lead c Zinc c

Land use

Lawns 602 9.1 2.1

Commercial Streets 468

Auto recyclers 335

Industrial parking 228

Landscaping 94,000

Residential streets 37,000 0.55

Driveways 2.1 0.56

Urban Highways 3 0.32 54 400 329

Rural highways 22

Industrial roofs 62 43 13900

Heavy industrial land 148 290 16000

Water Quality

Standard

30 126 0.05 13 65 120

Notes: a = mg/L, b = colony forming units per 100 mL, c = micrograms. TSS = total

suspended solids, TN = total nitrogen, P = phosphorus

The main purpose of traditional urban drainage is to convey precipitation from the

point of impact to receiving waters (Kiebler, 1982). The traditional system does not

consider water cleansing until it is at the end of the chain in a treatment plan. (Swan,

2003). In contrast, SUDS are designed to remove pollutants during several stages,

as part of a treatment train; with the cleansing of water referred to as good

housekeeping. Described on Table 2.3 on the next page (see Appendix D for further

detail)

36

Table 2.3: Pollutants removed in SUDS (Adapted from Wilson et al., 2004)

Pollutant Removal Mechanism

Nutrients Sedimentation, biodegradation, perception, de-nitrification

Sediments Sedimentation, filtration

Hydrocarbons Biodegradation, photolysis, filtration and absorption

Metals Sedimentation, absorption, filtration, precipitation, plant uptake

Pesticides Biodegradation, absorption, volatilisation

Chlorides Prevention

Cyanides Volatilisation, photolysis

Litter Trapping, Removal during routine maintenance

Organic Matter Filtration, sedimentation, biodegradation

SUDS techniques to manage stormwater pollution can be delineated into two groups

‘structural’ or ‘non-structural’ (Stovin et al., 2007). According to Sieker (2010), ‘non-

structural’ techniques are associated with subsurface measures of proprietary water

filtration that include permeable pavements and filter strips. ‘Structural’ techniques

imply a ‘softer’ engineering approach to drainage through the use of green roofs,

soakaways, swales, infiltration trenches and balancing ponds (Hamill, 2011). SUDS

techniques can be implemented on an individual basis or in a combination of several

measures that from a treatment train (Abbott et al., 2013). Dickie (2010), advocates

the treatment train as a framework (Figure 2.3.) when implementing SUDS

measures, as a means of incorporating SUDS holistically.

Figure 2.3: The Treatment Train

(Woods-Ballard et al., 2007)

37

The applicability of SUDS treatment-train is highly dependent on each individual

urban context including factors such as the percentage of green space, typology and

climate of the area. In addition, the awareness of stake holders and legislative

controls in terms of runoff, erosion and sedimentation and water quality control also

need to be considered (Apostolaki et al., 2009). Figure 2.3 creates a fundamental

framework for planning of SUDS. The hierarchical approach is utilised to re-create a

natural pattern of drainage, as set forth in ICOP (DEFRA, 2004):

Prevention – the use of good site design and housekeeping measures on

individual sites to prevent runoff and pollution (examples include minimising

paved areas and the use of sweeping to remove surface dust from car parks).

Source control – control runoff as near as possible to its source (such as the

use of rainwater harvesting, pervious pavements, green roofs or soakaways

for individual houses).

Site control – management of water from several sub-catchments (including

routing water from roofs and car parks to one large soakaway or infiltration

basin for the whole site).

Regional control – management of runoff from several sites, typically in a

detention pond or wetland.

By combining many incremental changes in overall SUDS a scheme, a system is

created where if one feature fails others will continue to work. The links in the system

should include surface routing through natural swales and trenches, if possible,

rather than artificial pipes (Shaw, 2011; p479/480). The approach is also echoed by

Illman (2011) when she states, that often SUDS measures are likely to fail or

underperform if perform if the treatment train is not completely understood and

implemented appropriately. (See Appendix E for further detail)

2.2.3 Deterrents of SUDS applications

The subject of SUDS has many perceived barriers. These barriers are quantified in

research undertaken by Apostolaki (2009) whereby the perception of UK

professional in SUDS participated in focus groups surveys. Figure 2.4 represents the

main barriers of SUDS implementation indicated by participants.

38

Figure 2.4: Bar chart of perceived barriers to SUDS application

(Apostolaki et al., 2009; p123)

The resulting survey indicates that the highest perceived issue with SUDS use

relates to adoption and maintenance. This is a deterrent as developers involved in

SUDS must take responsibility for the SUD scheme or hire someone, as appose to

traditional drainage systems where the local sanitary authority will take responsibility.

Butler (2011) states that the current juxtaposition between SUDS and piped

drainage, as being normal for traditional piped drainage to be adopted by water

authorities who include it as a revenue earning asset.

However, there remains a dispute between water authorities, road departments,

local authorities and developers on adoption and maintenance of SUDS measures

as they can be considered a landscape feature as appose to being a drainage

feature. CIRIA (2003) hypothesis, that the issue of institutional barriers can be

overcome through a long-term holistic framework that integrates design,

construction, maintenance and adoption early on in the planning of SUDS.

0

2

4

6

8

10

12

14

16

18

20

19.6

18.5 17.5

15.2

10.8

6.8

4 3.8

2.2 1.1

0.5

Adoptation of maintenance

Developers & planners reluctance to apply SUDS

Landtake

Not enough knowledge

W.A. Relucance to accept SUDS

Cost

Public perception

Safety

Bad practice examples

Improper planning & Landscapeing

Increased rainfall due to Climate Change

39

Butler (2010) argues that long-term maintenance is required for all types of

infrastructure, and the fact that SUDS maintenance should not place them in a

disadvantageous position. Bray (2001) goes on to argue that:

“The management of SUDS schemes has been seen as a major barrier to their use

in the UK although there is little evidence to support this concern”

Likewise, the negative perception of the widespread use of SUDS to replace

traditional drainage by developers and planners (20%) is also a barrier. Woods-

Ballard (2007) found that design guidance together with examples of existing

exemplar SUDS devices can overcome negative perceptions and confidence in

these approaches. Landtake also figured highly amongst the barriers as it represents

a change in traditional drainage practice. The out of sight, out of mind approach to

underground piped drainage systems requires only minimal land take. It is perceived

that ‘above ground’ SUDS will have a larger landtake, as it is not always the case; it

depends on the SUDS device and site condition (O’Sullivan, 2011). This often

encourages developers to take preferences constructing ‘below ground’ SUDS, as

appose to above ground systems which have a superior performance, are easily

maintained and little pipe blockages (Woods-Ballard et al., 2007). When SUDS are

considered early on in a project, land use becomes much less of an issue, and can

be integrated into a development without any constraints (Dickie et al., 2010).

Lack of experience, knowledge and appropriate training within SUDS experts was

cited by 15% of the survey participants also being a deterrent. Another significant

barrier is the perceived cost of SUDS schemes. This reflects a poor understanding

by participants as the cost of SUDS is comparable to conventional drainage (Butler,

2011). This issue was also raised in research by Duffy (2008) when comparing costs

and maintenance of SUDs to an equivalent traditional drainage solution. The

research indicated, that when SUDS is implemented as part of a well designed and

maintained plan, that it is more cost effective to construct and to maintain as oppose

to traditional drainage solutions.

40

2.3 Retrofitting SUDS

With insufficient evidence of retrofitting SUDS in Ireland, it is important that the

literature reviewed examines the background of retrofitting SUDS in a number of

other countries as doing so will provide a foundation development for retrofitting

guidance in Ireland.

2.3.1 Ageing infrastructure and the need to upgrade and retrofit

Successful urban drainage systems provide a clean and healthy environment for the

public. The urban landscapes canvas of architecture, networks and public spaces

are continually being modified. However, the urban drainage network slowly

degrades over time as the urban landscape moves forward. (Novotny et al., 2010,

p59). Upgrades to rehabilitate and maintain ageing infrastructure cannot meet

demands from the urban expansion (Marsalek et al., 2007, Ashley & Cashmann,

2006). Gaudreault (2006) warns that there is a degree of uncertainty regarding

financial incentives to support the rehabilitation and upgrading of urban drainage

systems, as it is normally only considered when an extreme flood event occurs.

However, as stated previously; retrofitting SUDS can be a cheaper alternative to

traditional measures and in a high percentage cases will provide extra benefits

(Ashley, 2011, p4).He goes onto state that, urban regeneration to reduce flood risks

and/or pollution provides an opportunity to manage surface water in a different way.

Progression towards SUDS retrofits would move away from traditional approaches of

piped based sub-surface systems, to one that uses a wide range of source control.

The term ‘Retrofit’ is identified as an approach to replace and/or augment an existing

drainage system in a developed catchment with a more sustainable technique

(Stovin et al., 2007). Ashley goes on to reiterate the importance of this potential

paradigm shift when stating:

“Taking this approach means that urban areas are enhanced to create better

places to live. This will deliver a wide range of benefits than previously

experienced”. (2011, p, xii)

41

An example of a SUDS retrofit would be the disconnection of roof runoff from a

combined sewer and its diversion into a waterbutt, or onto permeable yard.

Essentially, SUDS retrofits aim to replace conventional stormwater components from

an overall system, thus eliminating treatment and pumping costs and associated

energy requirements (Swan, 2007; p2).

As mentioned, the implementation of SUDS in the UK and Ireland has focused

mainly on new developments (Stovin et al., 2007). Retrofitting SUDS is a growing

trend within the UK. However, Ireland has fewer examples of SUDS retrofits that

experience can be drawn from. As with any new concept, SUDS retrofits has been

met with scepticism (Sniffer, 2006). Heal (2003) conveys, that this may be as a result

of the differing constraints of retrofits compared to new development, when stating:

“SUDS retrofits may be highly restricted by the area of land available and the

needs of existing landowners and users” (p3)

Although, in a Cost Benefit Analysis (CBA) of the retrofit of SUDS to urban areas,

Gordon-Walker (2007) highlights that 50% of public buildings could be upgraded with

SUDS retrofits and similarly 75% of industrial and commercial buildings.

Internationally, there are many examples of successful retrofit SUDS

implementation, most notable USA, Australia, Sweden and the Netherlands

(SNIFFER, 2006, p1). Ashley (2011) identifies core objectives as a basis to enabling

a successful SUDS retrofit:

Improve the quality of life for people by improving the quality of public space

Manage and reduce flood risk

Improve water quality

Improve biodiversity

Create solutions that can be simply and effectively maintained and adapted

over time

(p43)

42

2.3.1.1 A foundation for retrofitting SUDS

The retrofit of SUDS is not entirely down to the physical characteristics of identifying

and implementing techniques, it relies on an integrated approach to achieve multi-

functional benefits, something that is difficult to conceive for management and

development bodies that operate in isolation (Ashley, 2011; p10).

When analysing UK and Scottish legislation, it is clear that steps have been taken

towards a more integrated approach in planning policy that include SUDS retrofits

(e.g. Flood and Water Management Act 2010 & Flood Risk Management (Scotland)

Act 2009). As SUDS have been established in Britain’s legislation for over ten years,

advancements have been to address drainage issues holistically (Swan, 2007). As

appose to the Irish planning system in which SUDS is still a fledgling concept.

Ashley (2011) conveys that although progress has been made in Britain in terms of

SUDS, retrofitting SUDS has not yet become commonplace of drainage upgrades.

Furthermore stating, that for retrofitting to reach critical mass practitioners would

require more dedication, forward planning and to work as part of a multi-dimensional

team.

43

2.3.1.2 Feasibility

The framework associated with retrofitting is relatively straightforward (See Figure

2.5). Retrofit SUDS can be implemented quite like the treatment train either at a

small, local, or larger catchment scale (SNIFFER, 2006). There are two main

opportunities associated retrofitting SUDS (Ashley et al., 2011).

The first is the opportunistic ‘nibbling’ approach, utilised in urban regeneration where

the primary aim is not one that originally focused on drainage improvement, but of

site development or urban regeneration (Kellagher et al., 2008). Usually, this type of

opportunity will exploit the notion of ‘no space is useless’, occurring on small areas of

plots of land. The second is a strategic catchment based primarily on improvement of

water quality or to minimise flood risk.

Figure 2.5: A framework for retrofitting.

(Ashley et al., 2011; p38)

44

According to Ashley (2011), strategic catchment approach drainage designs and the

opportunistic approaches are equally important. Invariably, planners and drainage

designers are familiar with this catchment based approach. For large areas a

scorecard assessment can be implemented for a fast track approach (seen in

Appendix M). However, it is the opportunistic incremental measures, as for example

small plots on a small scale that can provide a real difference in managing surface

water sustainably. Over time, the measures will accumulate to deliver substantial

benefit. Such approaches can be very cost effective but may be limited to simply

addressing immediate needs such as existing flooding (Ashley et al., 2011).

Past experiences in other countries have shown that not all SUDS techniques lack

the adaptability to be implemented as an urban retrofit. It is also highly dependable

on area and context (EA, 2007, p4). Ashley (2011) highlights that types of

opportunities can be put into 3 groups:

Target opportunities: Those where large proportion of surface runoff can be

removed from and existing drainage system, or detained in storage, with

minimum new infrastructure (Stovin et al., 2007).

Common opportunities: Individual plots that are similar across estate or

neighbourhood offer an opportunity to standardise retrofit measures across

the area

Future opportunities: This provides the chance to retrofit measures possibly

as part of a wider work programme (e.g. Regeneration or adaptive drainage

measures).

(Ashley et al., 2011, p89)

(See Appendix k for a further description and implementation opportunities for SUDS

retrofit)

45

2.3.1.3 A decision-support system for retrofit of SUDS

The decision-support framework (DSF) is a method of identifying whether urban

areas, specifically urban roofs were applicable for retrofitting SUDS. The framework

applies a straightforward flow chart which aims to be as cost effective as possible

(Stovin et al., 2003).

Atkins (2004) comments that the hierarchical means of assessing whether a surface

is deemed plausible is broken up into for headings to consider based partners

involved, applicability and most cost effective. Each option ranges in order of

context most deemed suitable from intuitional roofs deem the most applicable and

cost effective to highways considered the most costly.

Figure 2.6: The four hierarchies of the retrofit SUDS decision-making framework

(SNIFFER, 2006, p5)

46

2.3.1.4 Challenges of retrofitting SUDS

To achieve a SUDS retrofit it is important to understand constraints at multiple scales

in order to integrate mitigatory measures. Systems planned can manage any

anticipated difficulties that are likely to occur.

Several authors have produced useful recommendations and guidance in this regard

including Ashley (2011) and Shaw (2004). The initial land uses/availability, existing

utility services and public involvement stages are particularly important and require

careful planning (WSP, 2009).

Land use: Land use is under estimated when developing a SUDS retrofit into

existing landscapes. Ashley (2011) cites that for new builds this should also

be a key issue. He goes on to emphasise that early dialogue with local

communities; innovative design and a partnership opportunity should be taken

to develop a multifunctional area that overcomes this challenge. Stovin (2007)

hypothesises, that different land use types will have different retrofit SUDS

opportunities, as well as risks associated with disconnection (pollution levels).

Furthermore, similar new build SUDS scheme, different land uses are

expected to utilise individual SUDS retrofit measures, as well as associated

risks with disconnection (pollutant level).

Existing Infrastructure: It is the nature of retrofitting in urban areas that

there will be existing services (Gas, Electricity, and Water) underground. It is

unlikely, due to expense or logistics that these services will be re-routed.

When one is weighing-up a particular retrofit, it is important that retrofit

feasibility is evaluated on a site-by-site basis and early consultation with utility

providers, to establish an effective working partnership (WSP, 2009).

Consultation: According to Ashley (2011), early consultation will mitigate any

public scepticism that may be as a consequence to SUDS measures being

unfamiliar. This should illustrate the broad benefits of adopting SUDS over

traditional forms of drainage.

47

2.3.1.5 The benefits of SUDS retrofits

The majority of tomorrow’s urban areas will be an evolution of today’s urban area

(Evans, 2013). Unlike today’s drainage approaches, the majority of SUDS retrofit

components manage runoff using multifunctional spaces (Ashley, 2011). According

to the Society of Chief Officers of Transportation in Scotland (SCOTS), there are a

number of potential benefits to retrofitting SUDS:

Infrastructure Benefits

Improvements of infrastructure

Reduction in sewer network flooding

Reduction in sewer and waste water treatment works maintenance burdens

Reduced future maintenance costs

Environmental Benefits

Improvement in water quality to receiving watercourses

Enhancement/provision of habitat

Ecological improvements/biodiversity enhancement

Amenity Benefits

Provision of public amenity area

Provision of educational/scientific site

(p104, 2009)

It is important to note that not all SUDS retrofit schemes will accrue all the above

benefits. Benefits will clearly relate to the nature of the SUDS features being

implemented as part of the scheme.

48

2.4 Legislative context for stormwater management

Before analysing the legislative context of stormwater management, it is helpful to

refer to the methodology. The literature chosen emphasises the context of developed

approaches to stormwater management. A general review of legislation in which the

concept of SUDS was derived from will be established. This includes North America,

Europe and the UK.

2.4.1 International legislation relating to SUDS

2.4.1.1 Background

As a concept, the idea of stormwater management in legislation can be traced to the

environmental movement which began to emerge throughout the 1960’s in the US.

There was a growing awareness of the environment and the detrimental effect that

development was having on the environment (Welford, 1995). The passage of the

Clean Water Act by the U.S, Congress in 1972 marked a paradigm shift in

environmental legislation regarding water and waste management in the United

States. This manifested on a worldwide scale by creating impetus for many countries

to adopt their own water and pollution management, and legislative controls

(Novotny, 2003, p25). This was also added to in 1972, with the publication of the

Club of Rome report ‘limits of growth’ which shaped the perceptions of sustainability

today (Meadows 1972). This created a platform for environmental awareness on the

limitations of the Earth’s resources and its degradation through poor practice.

Environmental concerns had transformed into a movement by the 1980’s, and the

world commission on Environment and Development (Brundtland commission)

published ‘our common future’ (WCED 1987). As discussed in previous chapters

(section 2.2.1), this introduced the key principles of self responsibility, not passing

environmental problems to elsewhere or the future (Jacobs, 2008). The idea of

sustainability grew from the landmark phrase which first appeared in 1987:

"Development that meets the needs of the present without compromising the

ability of future generations to meet their own needs."

(Brundtland Commission, 1987)

49

By 1992, there was a greater understanding of sustainability in urban drainage

marking the signature of the UN’s 1992 Earth Summit in Rio de Janeiro (Apostolaki

et al., 2009) (as seen in section 2.2.1). The twentieth century brought with it a new

direction for urban drainage in Europe, goals shifted from protecting their public from

disease and death to broader goals of protecting the well-being of people and

aquatic biota and promoting safety for those using bodies of water for recreation as

discussed below.

2.4.2 European legislation relating to SUDS

Over the last century, Europe has been subject to more than 213 major flood events

with long lasting damage, including the catastrophic floods of 2002 and 2007. Severe

floods in 2005 further reinforced the need for concerted action. Between 1998 and

2009, floods in Europe were responsible for 1126 deaths, the displacement of about

half a million people and at least €52 billion in insured economic losses (EEA, 2009).

Due to the diverse range of hydrological stressors across Europe, European

Legislation is made up of a complex network of Directives that determine how water

is managed in Europe. The key European Directives on the protection of urban water

and habitats are the Water Framework Directive (EC, 2000), the Flood Directive (EC,

2007) the Groundwater Directive (EC, 1980), and the Habitats Directive (EC, 1992).

In brief, as noted by the SUDS manual (2004) the Groundwater Directive’s main goal

is to prevent or limit discharge of a range of toxic substances into groundwater. The

Habitat’s directive provides European communities with protective legislation of flora

and fauna, which are of European significance. As the WFD and Flood Directive are

of significant relevance to the study, greater detail is given below.

European Water Framework Directive 2000/60/EC

The WFD sets out to establish a framework that safeguards Europe’s water through

improvement and conservation of surface and groundwater quality (Butler, 2011 &

Apostolaki, 2009; 49). Although, the WFD does place direct impacts on drainage

design or operation, it has established new environmental objectives for water

management (Shaw, 2011, p137). Targets of ‘good ecological status’ (GES) in

surface and groundwater systems should be achieved by 2015. The term ‘good

ecological status’ refers to a classification of the ecological status water bodies,

ranging in five classes- from high the most ecologically sound and bad being the

50

most polluted. It also requires the prevention of deterioration of a water body from

one status class to another – typically as a result of urbanisation (O’Connor, 2012,

p7). The WFD applies two objectives to European water in order to achieve ‘good

ecological status’ .Firstly, European countries must:

“Prevent deterioration of the status of all surface and groundwater bodies, and

secondly, protect enhance and restore all bodies of surface water and

groundwater” (Shaw, p137, 2011).

The main catalyst for attaining a GES was through the integration of River Basin

Management Plans (RBMPs). It is evident in the literature of O’Connor (2012) that

unless changes in urban drainage in Ireland transpire, the Water Framework

Directives objectives aren’t achievable, when he writes;

“The WFD cannot be met unless sustainable drainage systems (SUDS) are

implemented, as they offer an integrated approach that could play a key part

in delivering the Directive’s requirements”. (p7)

Little has been legislation has advocated the use of SUDS since the initial

implementation of the GDSDS (2005) over 9 years ago, as such it is clear from figure

2.7 that Ireland is failing to achieve targets set by the WFD.

Figure 2.7: Surface water bodies currently failing good status/nutrient conditions

51

Irish objectives under the WFD suggest, a very low ambition in restoring GES by

2015, keeping the biggest efforts for water restoration and improvement for the final

management cycle of 2021 (see figure 2.8). However, it is not known what

punishment (if any) Ireland can expect for missing targets.

Figure 2.8: Good Status objectives for surface waters

as set in the RBMPs expressed as the percentage of currently failing water bodies to

be restored to ‘Good Status’.

Time extensions in relation to Ireland, are mostly justified due to lack of ‘certainty of

cause’ or due to ‘physical recovery’. Extended deadlines until 2021 for meeting GS

are applied to 31% of surface water.

Hamill (2011) notes how natural wetlands, for example floodplains and marshes are

valued for their ability to store floodwater, improve water quality and provide

biodiversity. The European Environmental Bureau (EEB) found there has been

limited evidence to suggest that progress in environmental ambitions or changes in

planning frameworks as required in achieving a more sustainable water

management set out by the WFD (EEB, 2010). As the federation of emerging

environmental EU policy, the EEB (2010) states:

52

“This snapshot has raised serious doubts over the effectiveness of the WFD

implementation to change specific and well known unsustainable water

management practice”. (p4)

Adoption of EU Directives in Ireland

In Ireland, the Office of Public Works (OPW) oversees flood risk management and

applies catchment flood risk assessment and management (CFRAM) studies, as part

of the national flood mapping programme as part of the requirements of the Flood

Directive (EC,2007). The Environmental Protection Agency (EPA) in Ireland is

responsible for protection and management of the environment and water quality. It

involves government and public bodies; businesses and industry; as well as

members of the public, working in partnership. In common with other Member

States, Irish plans recognise that it will not be possible to meet the 2015 deadline in

all cases (EA, 2011).

(Please see appendix G (ii) for details on adoption measures in the UK and

Scotland).

53

2.5 Irish legislation on surface water drainage

The legislation relating to drainage practice within Ireland is multifaceted. As SUDS

have only become established within the Irish planning context, as a result SUDS

retrofits are not addressed directly. (Please see appendix H (I) for the historic

development of drainage in Ireland).

2.5.1 Irish legislative context

Stormwater management in Ireland is a highly regulated activity that is subject to a

number of domestic and EU legislation which drainage in Ireland historically related

to new development and was covered by the following acts:

Local Government (Sanitary Services) Acts (1878 to 1964)

Building Regulations (Government of Ireland, 1997 to 2010)

Planning and Development Act (2000)

With the introduction of the Water Framework Directive (2000/60/EC) (WFD) Irelands

legislation progressed significantly in an effort to support the implementation of the

Directives requirements and associated requirements for river basin management

plans (O’Connor, 2012, p36). The WFD was transposed into Irish legislation under

the:

Water Policy Regulations (2003)

The Greater Strategic Dublin Study (2005)

The Surface Waters Environmental Objectives Regulations (2009)

The Groundwater Environmental Objectives Regulations (2010)

Historically, all local authorities serve as the sanitary authority (SA) under previous

legislation with the aim of meeting legislative objectives within differing catchments.

Subsequently in 2013, the Water Services Act (2013) provided for the transfer of

water services functions from the Local Authorities to Irish Water. Irish Water is the

new national water utility responsible for the delivery of water services including,

supply, water quality and waste water for homes and businesses in Ireland (Irish

Water, 2014).

54

Figure 2.9: The serial approach to Stormwater management in Ireland

(Stahre et al., 2003; p9)

Highlighted above is the serial approach of how stormwater management and

planning and implementation are approached by local authorities in Ireland. It is

important to stress that Irish Water may approach drainage differently. However, it is

too early to predict, and thus the research will be based on the existing framework.

The planning framework in Ireland utilises a linear approach to the management of

drainage demonstrated within it. An integrated planning system which is necessary

for a holistic approach to drainage could never be attained through the above

framework. Stahre (2003) argues that the linear approach to planning stormwater

management measures could never fully meet the intended goals set out by

government policy papers. The rigid approach of figure 2.10 does not allow for the

necessary flexibility that is required for stormwater management. Each stage and

profession involved from planning to implementation is highly diverse and skills differ

significantly. The approach lacks coherency as interaction between planners and

maintenance personnel rarely occur (Stahre et al., 2003)

Dublin’s legislative context

Stormwater attenuation has been required in Dublin City since 1998 when Dublin

City Council introduced the Stormwater Management Policy (DCC, 1998). This made

it mandatory for all new developments to limit run-off to pre-development rates.

However, this policy provided little guidance on best practice methods to improve

water quality and resulted in the widespread adoption by developers of hyrobrakes

or similar storage devices to control runoff. This resulted in maintenance and

cleansing issues, with massive cost implications for developers to construct

55

underground tanks (Hennelly, 2005). This approach of ‘hard’ solutions also had

environmental implications with tanks regularly exceeding capacity and overflowing,

which meant untreated water would often leech into water bodies or groundwater

(O‘Sullivan, 2011). Since the publication of the Greater Dublin Strategic Study (2005)

(GDSDS) it has become mandatory for all new developments to incorporate SUDS

where practical. Craven (2014) comments, that although steps have been made

towards sustainable forms of drainage, no formal handover or explanation of change

in policy was provided to local authorities or training in SUDS for the implementation

of the policies. Going on to state that:

“Initially it was difficult to get developers to comply. Developers gave reasons why

SUDS were unfeasible and these were often accepted unchallenged. Very few

sustainable drainage methods were incorporated into new development. In general,

underground tanks and hydro-breaks were installed”

In a national study conducted by O’Sullivan (2011) that targeted all sectors of

stormwater management, this adoption measure resurfaces. The study found that

72% of respondents implement ‘hard’ solutions such as attenuation/ storage tanks

for managing run-off shown on Figure 2.10.

Figure 2.10: Adopted structural methods for attenuating stormwater and restricting outflows to predevelopment run-off values.

(O’Sullivan, 2011, p244)

56

Hennelly (2005) notes that those participants in the study, were slow to commit fully

to any form of SUDS as there are perceived concerns regarding safety,

maintenance, cost, land take site suitability and flooding issues. O’Sullivan (2011)

comments that the common concerns regarding SUDS, arise as to a lack of

knowledge over SUDS techniques that may be concurrent with a lack of Irish

guidance (shown below on figure 2.11).

Figure 2.11: Understanding of different techniques in the management train

approach to stormwater management.

(O’Sullivan, 2011; p244)

Conversely during an interview conducted as part of research study, John Collins a

(Senior Engineer of Dublin City Council), raises the issue that the GDSDS has

brought SUDS to the fore and;

“Some years ago very few people were concerned or knew about SUDS whereas

now it is common knowledge”

Also noted by O’Sullivan (2011) and Collins (2014) is that, the use of SUDS in

Ireland is rising due to the publication of the GDSDS (2005). However, developers

do not have a complete understanding of SUDS techniques still after 9 years in

policy. O’Sullivan (2011) explores this topic in a study focus group and on reflection

concludes that there is;

“...a poor understanding of the range of SUDS techniques among these respondents

and (this) suggests that SUDS are viewed in a narrow context limited only to

infiltration measures”

(247)

57

This issue was also raised by Doyle (2003), when emphasising that there are high

levels of scepticism due to a lack of understanding of SUDS. This scepticism eluded

to may be due to the fact that “No formal training was provided to the engineers who

were responsible for the implementation of the policies" (Craven, 2013).

Furthermore O’Sullivan (2011) notes, during a research focus group that the

interviewees in engineering and architectural consultancies commented on the lack

of knowledge in house as an issue of implementation; “Lack of familiarity is a

problem. Neither architects nor engineers are familiar with it” (247). Kellagher

(2008) comments, that the local authorities in the greater Dublin area face a

challenge in educating practitioners on the new approach and to adopt best practice

SUDS methodologies.

2.5.2 Irish SUDS design standards & guidance

Generally, SUDS as a subject that has a number of technical guidance and is well

resourced and can be simply researched. The guidance has been established by a

number working group’s involved urban drainage. Guidance has influenced the

decision making regarding SUDS models and set out current best practice standards

on the topic (Shaw et al., 2011, p486). SUDS design guidance in Ireland is currently

drawn from a number of sources (O’Sullivan, 2011). These sources range from local

authorities to USA EPA (cited on Figure 2.11)

Figure 2.11: Guidance material commonly used by respondents in SUDS design.

58

In some cases the specific guidance contained within these documents has been

based on a combination of scientific, practical and historical considerations (Shaw et

al., 2011, p486). There can be variations in the advice given to practitioners in

different situations. As shown on figure 2.11, CIRIA is one of the most influential

groups to provide guidance on urban drainage. There are four key documents of

direct relevance for SUDS in Ireland are provided in (Appendix I).

Figure 2.12: Summary of additional information

In the UK, the promotion of SUDS in national guidance was a primary driver behind

SUDS reaching the critical mass (Bray, 2013). Figure 2.12 indicates the need for

national guidance in Ireland to achieve results seen in the UK (O’Sullivan et al.,

2008). Guidance can create a foundation for SUDS principles in Ireland and a

potential for implementation of SUDS on an extensive scale while also creating

coherency in standards.

2.5.3 Implementation of SUDS to date in Ireland

Currently in Ireland the inherent use of SUDS has solely focused on new build

development, as mentioned in previous chapters. Ireland has been limited in the

uptake of SUDS in comparison to other parts of the world, notably the UK, USA,

Scandinavia and mainland Europe. From a retrofit perspective, this literature review

only uncovered one documented assessment of a SUDS retrofit in Ireland. This is a

small scale stand alone sewer separation project in Kimmage, Dublin that utilised a

59

hydrodynamic stormwater separator for the removal of suspended solids (Ashley et

al., 2012; 182). This system was installed as part of the collaboration between Trinity

College Dublin and Dublin City Council and has inherent issues with maintenance

and clogging (Craven, 2014). As illustrated, there are a number of documented

schemes from other parts of the world, most notably within Scandinavia. A number of

examples from Europe are presented within the ensuing Chapters 3 and 4.

2.6 Barriers to the implementation of SUDS in Ireland

In Ireland, the perceived deterrents correlate with studies reported elsewhere (see

figure 2.13, section2.3.3) and mitigatory measures have been explored in prior

sections (e.g. Apostolaki et al., 2009; Ashley et al., 2011; Butler, 2011).

Figure 2.13: Perceived deterrents to the implementation of SUDS in Ireland.

The key difference between the focus groups in the UK and Ireland (figure 2.14) is

the lack of clear guidance cited by over 9%. O’Sullivan (2011) suggests that;

“Guidance for the design and implementation of SUDS in Ireland is currently drawn

from a range of diverse sources. A holistic and integrated approach to stormwater

management would therefore benefit from national guidance (preferably supported

by software) for SUDS design” (p250). This suggests that new guidance is a method

of overcoming perceived barriers of SUDS implementation in Ireland.

(See appendix J for an developing a SUDS cost benefit analysis (CBA)

60

2.7 Summary of main findings for a SUDS retrofit

If a SUDS retrofit is to be successfully adapted to Glasthule village, the following

activities are necessary:

Employ a more integrated approach to planning stormwater drainage where stormwater is a resource.

SUDS cannot be subject to new builds alone as they only make up 1% of construction.

Retrofit SUDS as part of incremental changes.

Use above ground SUDS where possible.

Overcome perceived barriers through new national guidance and create workshops in order to reach the critical mass.

The actions can establish a network of SUDS schemes that provide increased

resilience to the future problems and would be a step forward for Dublin and Ireland

in meeting the targets set out by the WFD. There are various matters that need to be

considered when assessing the inclusion of a SUDS retrofit into an existing context.

However, in order to convey a transparent process of research, table 2.4 was

developed to illustrate frameworks and tools with that could assist specifically for

retrofitting SUDS in Glasthule village.

Table 2.4: Key Frameworks for a SUDS retrofit

Framework Key Data Lessons learnt

SUDS Tri-Ring Model Amenity

Quality

Quantity

The integrated approach of hydrological performance, water quality and amenity creation is managed equally

The Treatment Train Prevention,

Source Control,

Site Control

Regional control

The hierarchical approach is utilised to re-create a natural pattern of drainage

A framework for retrofitting SUDS

Preparation

Feasibility

Develop options

Appraisal

Implement

Performance monitor

A starting point the adoption of a SUDS retrofit in urban areas that provides guidance from implementation to finish.

Description and implementation opportunity for SUDS retrofit

Technique

Description

Implementation

Scenario

The framework provides guidance on different scenarios that provide an opportunity to retrofit.

SUDS decision making framework

Institutional

Car Parks

Residential

Highways

identifying retrofit SUDS options to deliver hydraulically straightforward solutions and cost-effective to implement

61

CHAPTER 3. CASE STUDIES: MALMÖ AND SHEFFIELD.

“Water is the great connector and coordinator”.

-Eckbo (1990, 3)

3.1. Introduction

Chapter two reviewed the key issues in the literature that are pertinent to this study.

This chapter addresses how these issues might be investigated empirically in a

series of two case studies; in Malmö (Sweden), Sheffield (United Kingdom). In

addition to a further case study was undertaken on Den Haag (Netherlands) in

Appendix B. The research employed a case study strategy to understand the

context-specific nature of each areas sustainable stormwater management (Morris

and Wood, 1991). The case studies provide general project detail, historic site

constraints, retrofitted SUDS solutions and actions implement to identify those

factors that contributed to the success of SUDS retrofits.

The epistemological stance, theoretical perspective and the research questions

shaped the research design and hence the choice of methodology. This chapter

outlines the research methodology employed to conduct the primary research. The

context-specific nature of the case studies convey extensive benefits of retrofitting

SUDS which go beyond those experienced from conventional drainage solutions

The main objective of the case study research was to evaluate and compare

different stormwater management techniques, from a retrofit perspective, in three

major European cities .Two of the case studies are presented below and the third is

described in appendix B To meet the objectives the following tasks and actions were

undertaken:

To assess perceptions of environmental issues and flood related issues;

To evaluate the stormwater management strategies proposed;

To compare stormwater management practices in the three areas of interest.

62

3.2 Augustenborg, Malmo: Introduction

The case study of Augustenborg is located in the historic city of Malmö to the

southwest of Sweden, is situated on the edge of the Öresund and neighbours

Copenhagen in Denmark (shown below on figure 3.1). Malmö is Sweden’s third-

largest city, with a population of 286,000 (Kazmierczak et al., 2010).

Figure 3.1: Map of Sweden

(Stahre et al., 2008; p11).

3.2.1 Context

Malmö’s history is similar to many industrial port cities around the world. During the

20th century, it flourished as a centre for trade and commerce. However, the oil crisis

in the 1970’s caused closures of shipyards and textile industries generating high

unemployment (Hambleton, 2008). According to Fossum (2008), within the space of

3 years the city lost 30,000 jobs. The city responded through investment in

sustainability and knowledge based work.

The city now prides itself as a model of social and environmental sustainability. This

is reflected in the city’s cosmopolitan standards with residents speaking more than a

100 different languages and of 174 countries of origin (28% of inhabitants originate

from outside Sweden). It has a relatively young demographic profile with 50% of

people under the age of 35. (URBED, 2010; p2).

63

The 1990’s marked a turning point for water drainage in the City of Malmö with the

introduction of sustainable urban drainage. The concept was first applied to Toftanäs

Wetland Park in the eastern outskirts of the city. Pioneering approaches came to

fruition in an attempt to solve Malmö’s problematic downstream combined sewer

overflow. The system was constantly overloaded during periods of heavy

precipitation. Like many countries, stormwater management in Malmö was initially

based on quantity control, essentially detaining peak flows in urban runoff from new

settlements (Stahre et al., 2008; p3/15). Adoption of SUDS was hampered by high

levels of scepticism from officials in the city administration, stemming from

uncertainty regarding the new drainage system. Urban drainage is controlled by

Malmö Water, an inter-department of VA SYD, which oversee the widespread

adoption of SUDS (Nowell, 2009, Stahre, 2008).

From the initial development of Toftanäs Wetland Park, Malmö has seen an

unprecedented growth of new SUDS concepts with over 18 exemplars around the

city, with more anticipated. Consequently, this created a planning framework and

technical configuration that is continuously developed and refined (Adamsson,

2008). Progression saw initial implementation of local ponds- to today’s multi-

functional regional eco-corridors (Please see appendix L). According to Stahre

(2008, p6):“This change of view is a result of the process of constant learning, and is

based on the experiences that were gained from the implemented facilities”. Malmö

is now recognised as a European success for innovation and sustainable growth,

and the city's population is now expected to grow by 100,000 people, a third of its

current population, over the coming years.

64

3.2.2 Background- Augustenborg, Malmo

Augustenborg Eco-city was chosen as a case study. Augustenborg was built in the

1950’s, the district comprises of 1,800 apartments between 3-7 stories for 3,000

inhabitants, with open space, employment and social facilities; covering an area of

32ha in size.

Figure 3.2: Green areas-owned by Municipality. White indicates private ownership

(Nordregio, 2014)

Initially construction of Augustenborg was recognised as success in pioneering

development under Sweden’s first social housing policy (Kazmierczak et al., 2010).

The economic decline of Augustenborg coincided with that of Malmö. During the 70s

and 80s, deprivation engulfed the area with an exodus of residents, with properties

remaining unoccupied and the district had a high concentration of marginalised,

socio-culturally “vulnerable” people (Villarreal et al., 2004).

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The decline had repercussions on its ageing infrastructure, with annual flooding

causing damage to basements and garages. The ageing combined sewer system

was overwhelmed with exceedance water during heavy rainfall, household waste

water and pressure from other parts of the city (CABE, 2011). Untreated sewage

often entered watercourses as a result of increased pressure on the sewage

treatment works. In 1990, the Malmö municipality together with MKB (Malmö’s public

housing company) planned to refurbish Augustenborg. The model set out was an

‘eco-regeneration’ plan which incorporated a major urban renewal programme for the

next 7 years. The project was underpinned by research and innovation to shape the

Ekostaden (Eco-city) (Kazmierczak et al., 2010).

3.2.3 Developing the integrated retrofit proposal

It was decided that Eco-city Augustenborg renewal would be driven on the

philosophy of developing an eco-city friendly industrial park in an effort to renovate

the buildings, address flooding, improving waste management and enhance

biodiversity (Kibirige et al., 2013). To succeed with the targeted aims, it was

important this concept of SUDS considered the societal aspects associated with the

urban environment (Stahre et al., 2003), which is shown below in Figure 3.3.

Figure 3.3: Examples of values considered in the planning of sustainable stormwater drainage systems in Augustenborg

(Stahre et al., 2003, p16)

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Now recognised as a fully incorporated SUDS retrofit, Augustenborg implemented

strategies to control stormwater through a complex arrangement of green roofs,

swales, channels, ponds and small wetlands (Kazmierczak et al., 2010). One

overarching element of the project was public engagement. In an effort to promote

community involvement in the design process to shape the communal surroundings,

the lead landscape architect engaged with the stakeholders early on. As a result,

Augustenborg now includes a number of different and successful innovations based

on experiences from the engagement (Lundberg, 2014).

3.2.4 Sustainable stormwater legislation

The Rio Convention ’92 had a major influence on the legislation in Sweden. The

influence resulted in Malmö adopting the Local Agenda 21, a pivotal policy in

developing the long term sustainable objectives of the city (O’Byrne, 2008). One of

the policies the Local Agenda 21 implemented was the Stormwater Policy (2000).

This policy advocates early stage implementation of stormwater management

throughout the planning process.

The traditional approach to stormwater drainage (underground techniques) is the

responsibility of the local authority’s drainage department. The traditional model

(Model A) is a linear process described in Figure 3.4 below. This process was once

utilised by Malmö Municipality; however the pre-requisites for the planning evolved

with the introduction of sustainable stormwater drainage to Malmö (Stahre et al.,

2003). This new approach of planning stormwater implemented the concept of

integration; it sought to develop a planning process where a multidimensional team

of skilled practitioners were included in stormwater management planning (Model B)

(Beckmann, 2014).

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Figure 3.4: Models once applied and currently applied to Malmo. Model a (Left): The traditional process of urban drainage renewal. Model b (right): A schematic illustration of the planning of stormwater management in Malmö.

(Stahre et al., 2003; p15, 17)

It took over 10 years for Malmö’s traditional institutions to accept the new planning

approach. The previously used model (Model A) is now no longer regarded as

resilient in coping with stormwater. The introduction of new sustainable stormwater

management brought with it a new cumulative lateral process (Model B).Stahre

(2008) argues, that for stormwater management to be successful, it is requires

committed cooperation between a multitude of different partners.

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This integrated planning process is uncommon across the world. As it would be

unconventional for the planning and the implementation of jointly owned and

operated water facilities to fully collaborate on projects in many other cities. Progress

in planning is aided by the Municipality of Malmo owning 40% of the city’s area and a

larger quantity of the city’s budget than seen in other countries (URBED, 2010; p2).

The underlying philosophy of Malmö’s stormwater policy is based on the SUDS

triangle (see section 2.2.2, p30). Based on the basic principles outlined in the policy

document the following general goals were identified for the management of

stormwater:

The natural water balance shall not be effected by the urbanisation

Pollutants shall to the greatest possible extent be kept away from the urban

runoff (source control of pollutants)

The drainage system shall be designed so that harmful backing up of water in

the existing drainage system is avoided

The drainage system shall be designed so that part of the pollutants in the

runoff are removed along its way to receiving waters

Stormwater shall wherever possible be looked upon as a positive resource in

the urban landscape

(City of Malmö, 2000)

The ambitious policy was intended to create a framework where interdisciplinary

teams of city administration would be intertwined in decision making of civic spaces

(Stahre et al., 2008).

3.2.5 Design and implementation of SUDS retrofits in Augustenborg

The SUDS retrofit begun in December 1999 and continued until the summer of 2000

(Kazmierczak et al., 2010) in 2001 Augustenborg was disconnected from the existing

combined sewer and drained by means of an open stormwater system (Stovin,

2011).

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Figure 3.5: Overview of the stormwater system in Augustenborg

(VA SYD)

Table 3.1: Illustration of different solutions mentioned in Figure 3.5

Number Implementation Number Implementation

1 The Augustenborg botanical roof garden area

9 Basketball court, storm water collected here travel to 10

2 Storm water storage pumped underground from storage area

10 Ditch through the park

3 Concrete canal 11 Outlet pond Nr 1

4 Wetland 12 Storage pond

5 Onion gutters 13 Macadam-bottomed ditch

6 Storage pond 14 Storage Pond

7 Block flat with green roof 15 Constructed tone canal

8 Cube canal 16 Outlet pond Nr 2

In order to achieve the city’s goals of regenerating Augustenborg into an

environmentally friendly, physically and socially attractive neighbourhood, the project

was implemented as an integrated design process (CABE, 2011). The stormwater is

managed through one inlet pond and two outlet ponds. Firstly the stormwater is

collected and accumulates in the storage area (see Figure 3.5 and Table 3.5). Then

water is pumped below ground and flows into a ditch system through the inlet pipe.

Water then flows to the long ditch system indicated as a blue line on Figure 3.5 and

thereafter stormwater travels to the outlet ponds for attenuation. To slow down the

peak flows of runoff, a number of SUDS techniques collect water from rooftops and

other impervious surfaces through gutters and route the water through canals,

ditches, ponds and wetlands before finally percolating in a detention basin (Kibirige

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et al., 2013).These changes have resulted in a SUDS retrofit that retains 70% of all

rainwater that falls onto the 32-hectare neighbourhood with botanical green roof

collecting 90% of rainwater For extreme rainfall, where SUDS can no longer handle

the excess; water can be diverted to a sewage system in Lönngatanm which has not

occurred so far. Ashley (2011) indicates that the success of eco-city Augustenborg

was due to the retrofitting key factors of:

Clear driver of urban expansion

Visionary staff and senior executives of a municipality willing to innovate and

take risks

Good co-operation between various departments and organisation

Opportunities related to normal regeneration of housing area

(p186)

3.2.5.1 Maintenance plan involved for SUDS measures

Maintenance is a constant barrier when implementing stormwater management as

shown in the literature review. Augustenborg overcame this challenge through an

early adoption of a plan making process that ensured; design, implementation and

maintenance were managed together (Stahre et al., 2008). Another common

problem avoided was the ownership of the maintenance of the storm water system.

With a wide range of stakeholders, it could have fallen under the responsibilities of a

number of departments (Kazmierczak et al., 2010).

The early inception of an integrated planning system created a foundation of

interaction where the housing company and the city could agree on a joint

management contract for the waste and water systems and the open and green

spaces. Management work is jointly funded through the housing company which

incorporates costs into rents, the water board through the water rates, and the city

council’s standard maintenance budgets (CABE, 2011).

3.2.6 Challenges faced and enabling factors of the SUDS retrofit

Challenges of the SUDS retrofit of Augustenborg were associated within the context

of the site. Common and important issues were raised by residents regarding the

aesthetic nature of the SUDS techniques used. The character of the neighbourhood

was important and damage to building was unacceptable from the outset.

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Further challenges are listed below.

Finding physical space to incorporate the SUDS into the already existing

development:

The SUDS had to be fitted around existing electricity, water, heating and

telephone infrastructure;

Access for emergency vehicles had to be maintained;

Many residents were concerned that large percentage of the accessible green

space was not suitable for recreation, and that some trees were removed.

Buildings could not be damaged by water. Thus, all SUDS were underlain with

geotextile, removing the possibility for increased deep percolation and limiting

the system’s function to water retention rather than infiltration.

Health and safety issues had to be solved. The SUDS were located within and

in close proximity to school grounds, and concerns were raised about the

drainage channels posing obstacles to elderly and disabled.

Aesthetics were more important to many residents than the functioning of the

system.

At the initial design stage of the project problems were ironed out with project

managers and the community. According to Lundberg (2014)

“problems were solved by redesigning, re-considering design features and in some

cases removing certain elements of the system, utilising technological solutions, and

extensive consultation with local residents”

Other problems associated with the project were the unavoidable noise and dust

during construction, which caused complaints from local residents. In addition, the

retention ponds were prone to algae growth, and a technical solution was designed

to solve this problem (Stahre et al., 2008).

3.2.7 Stakeholder engagement during the retrofit project

According to Lundberg 2014 “Significant public engagement took place for a greater

understanding of the Eco-cities aims”. This permitted to growth of ideas through

regular community workshops, meetings and informal gatherings at sports and

cultural events. The open and consultative approach taken, created a medium

through which residents could become actively involved in the upgrading of the

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settlement (Kazmierczak et al., 2010). Constant communication and in-depth

community involvement enabled the project to gain momentum and the design team

encountered little or no opposition to the plans.

3.2.8 Costs of the SUDS retrofit

The total sum invested in the physical improvements in Augustenborg and related

projects was around SEK 200M (Circa €24 Million). Around half of the sum was

invested by MKB. Remaining funding mainly came from the local authorities,

principally the City of Malmö, in addition to several other sources (Kazmierczak et

al., 2010).

3.2.9 Successful factors of the SUDS retrofit

A decade before the refurbishment of Augustenborg the idea of placing a pond within

a housing development would have been rejected immediately (Ashley et al., 2011).

However, it took 10 years to develop the cross administration co-operation among

different departments involved in drainage and planning. This created a platform for

the regeneration of Augustenborg to be based on quantity issues (flows & volumes),

quality issues (pollutants) and various social aspects (amenity and multi-function)

being dealt with concurrently (Rolfsdotter-Jansson, 2007). The 6km of canals and

water channels along with 10 ponds and basins in Augustenborg alone have created

the multiple benefits listed below:

90 % of the stormwater from roofs and other impervious surfaces is led into

the open storm-water system in the housing area.

Stormwater systems are now able to handle runoff volumes locally.

The implementation of an open stormwater system at Augustenborg has

improved the performance of the combined sewer system of the surrounding

area.

Biodiversity in the area has increased by 50 %. The green roofs have

attracted birds and insects, and the open storm water system provides better

environment for the local plant- and wildlife.

The volume of stormwater draining into the combined system is now

negligible, and this system now drains almost only wastewater.

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In addition, modelling work has shown that the total annual runoff volume is

reduced by about 20% compared to the conventional system, due to

evapotranspiration.

Significantly, there have not been any floods in the area since the open

stormwater system was installed.

The environmental impact of the area (measured as carbon emissions and

waste generation) decreased by 20%.

The participatory character of the project sparked interest in renewable

energy and in sustainable transport among residents

Between 1998 and 2002 the following social changes have occurred: (i)

turnover of tenancies decreased by 50%, (ii) unemployment fell from 30% to

6% (to Malmö’s average), (iii) participation in elections increased from 54 % to

79%.

The SUDS at Augustenborg continues to be reliant during extreme events, an

example of this is during a storm event in 2007 Sweden experienced an extreme

flood event that left Augustenborg cut-off from the rest of Malmo. According to

Lundber (2014) “the SUDS features in Augustenborg dealt with the extreme

precipitation successfully”. This indicates that the is performing better than

conventional design standards and that Augustenborg is well prepared for more

intense rainfall events in the future sources (Kazmierczak et al., 2010).

The green roofs in Augustenborg intercept around 90% of the total rainwater runoff

over the course of a year. In addition, the roofs have a significant cooling effect in the

summer when compared with standard black bitumen roofs. Consequently, their

presence (and that of more open water and green space) will help the area to adapt

to projected heat waves and higher temperatures associated with climate change.

The heat and hot water consumption has decreased by 25 %.

In addition, Rolfsdotter-Jansson (2007) highlights the positive effects of SUDS

retrofits by stating that Augustenborg has become an attractive, multicultural

neighbourhood in which the turnover of tenancies has decreased by almost 50 %

and the environmental impact has decreased by 20 %.

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3.2.10 Missed opportunities

Augustenborg is a clear exemplar of SUDS retrofits. It has achieved more than

initially expected when the project began and is recognised as an international eco-

city. However, it is the only retrofit project in Malmo currently. This emphasis the

institutional and funding challenges that retrofitting SUDS needs to overcome in

order to achieve a widespread implementation.

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3.3 Manor Fields Park, Sheffield: Introduction

Manor Fields, located two miles south-east of the city Sheffield, is a primary example

of sustainable design within a civic minded framework (Kennedy et al., 2007). The

study area blossomed through the industrial age on the strength of the city’s steel

industry. Once steel mills closed the city experienced social deprivation associated

with multigenerational unemployment, converging with architectural landscape

suffering though disrepair and poor investment (Bray et al., 2005).

Figure 3.6: Manor Fields Park Contextual Map

(Nilfanion, 2013)

Through the late 1990’s and early 2000’s the predominantly Council or other Social

Rented housing estates to north and south were listed as areas of strategic

development regeneration (Ashley et al., 2011; P191). The two phase regeneration

process included areas consisting of a diverse range of dwellings that were privately

owned and social housing.

In 2003 during the second phase of regeneration, when developing the north east

segment of the new Manor Fields (between City Road and Manor Park) it was

discovered that the proposed conventional gravity fed shallow sewer network would

not be suitable for existing surface water (Kennedy et al., 2007). Consequently 300

new dwellings would be unable to drain to the existing drainage pipes and alternative

method of drainage would need to be explored (Bray et al., 2005).

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Proposals included installing a permanent pump to transport stormwater upwards to

the main sewer and also tunnelling of a new connecting sewer 15 metres below the

surface. Both were deemed too expensive and unfeasible (CIRIA, 2014). The most

favourable option consisted of retrofitting SUDS. This would improve the

environmental quality of the existing 25ha district park of Manor Fields and drain

surface water to the new park. As a method of managing flow volume and quality

through a series of basins with eventual outfall to a local watercourse (Ashley et al.,

2011).

3.3.1 Drivers and Delivery

The perceived economical issue of high costs is a common stumbling block for

SUDS schemes in the UK and Ireland as shown in the literature review. However,

the SUDS retrofit was a financial success and saved of £50,000. As part of the

design code the scheme invested in green infrastructural elements to promote

development and management of the spaces in a mainstream construction setting

(Ashley et al., 2011).

The SUDS retrofit forms a structuring element in a natural way of treating rainwater

on site that created an ecological resource. From the beginning the park

development team within the Council maintained full control over the process of

design (LI, 2014). The design team utilised the existing undulating semi-natural

landscape in an attempt to create a space for recreation, ecological benefit, robust

and easily maintained (CIRIA, 2014; Ashley et al., 2011).

3.3.1.1 Retrofit Details

Ground conditions, time constraints and economics forced developers to implement

the retro-fit scheme as an end-of pipe system. Although not recognised at the time,

the approach utilised a hybrid drainage system involving the combined use of both

traditional and retrofit SUDS technologies to alleviate the catchments flooding

problems (as shown on figure 3.8) (Kennedy et al., 2007). Manor Fields design

originally intended to use traditional drainage. However it was unable to achieve the design

objectives and needed to implement an alternative method of dealing with surface water.

The chosen solution was a SUDS with an end of pipe retro-fit solution that had already

constructed stormwater routed through the housing project in a conventional pipe

network.

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Figure 3.7: Plan showing basin configuration (Ashley et al., 2011; p191)

The alignment and grading of the basins and wetland, combined with sensitivity to

the site's natural characteristics, diminish the velocity of run-off; bio filters and settles

pollutants that create an opportunity for groundwater recharge (LI, 2014). There are

4 major components to the system a sedimentation basin, infiltration basin,

connecting swales and treatment wetland.

At the uppermost part of the drainage system is a sediment basin, where runoff is

directed from one point, a 375mm pipe which discharges un-attenuated and

untreated stormwater from the contributing development (Kennedy et al., 2011). At

the beginning of the SUDS management train the basin stormwater undergoes

intense management in flow reduction, settling and treating gross particulate material

via UV, air and water. The basin also contains the most amount of debris,

subsequently removed monthly as part of the maintenance contract (Ashley et al.,

2011). According to Kennedy (2007), a silt fore-bay intercepts silt in the case of any

future pollution events that may occur; aiding protection to the subsequent two

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basins. The sediment basin is easily accessible for routine maintenance and the

removal of accumulated silt.

Runoff discharge from the sedimentation basin is conveyed to an infiltration basin

represented as a shallow wetland with a sand filter beneath an open jointed stone

wall. The highly permeable soils and the shallow depth of water is a conductive to

the infiltration of runoff and were designed to manage the first flush of runoff volume

in a storm event. These filters manage flow at a rate determined by the resistance of

the filter and the exit pipe-work cross-sectional area. When the flow exceeds the

infiltration capacity the low flow is discharged into the following basin through a grass

swale. The swales are designed to function as riparian corridors which support a

variety of micro- climates dependent on their different flood or drought conditions.

Where the two upper basins are unable to manage flows through their filters runoff is

discharged through an alternative meandering vegetated swale down to the next

basin (CIRIA, 2014).

The terminus of the treatment train is a constructed pond and wetland with good

quality water due to the previous filtration. The final basin has a volume release

control out to an existing dry valley which leads to a watercourse. During overflow

exceedance an outlet structure is designed to safely pass the volume of a 100-year

storm into a broad meadow (Bray & Nowell, 2005). Terraced basins are designed to

collect a 1 in 30 year storm volume of 391m3 with any additional volume flowing to

an arena area designed to accommodate a 1 in 100 year storm volume. The whole

system has a controlled discharge of 15.5L/sec, 10L/sec leaving the third basin and

5.5L/sec from the arena area. Meeting all health and safety criteria set out in current

guidance and the Royal Society for the Prevention of Accidents (RoSPA) the basins

have sequential levels and a maximum storage depth of 300mm with the arena area

having a storage depth of 600mm during a 1 in 100 year storm (Kennedy et al.,

2007).

3.3.1.2 Maintenance

The minimal approach to landscape alteration culminated in low maintenance

requirements for general up keep of the park. As the maintenance contract was

continued with the pre-development maintenance company the regime was simply

adapted for SUDS requirements (Ashley et al., 2011).Adoption and long-term

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maintenance is the biggest deterrent for developers for SUDS implementation in

Ireland and in England (see section 2.7) as no single entity currently represents the

operation and maintenance of SUDS (CIRIA, 2000:17). To the Contrary, Kennedy

(2007) argues that through resourcing Sheffield City Council Parks Development

Team were provided with enough power to adopt maintenance responsibility.

GreenEstate Ltd, a local landscape social enterprise, presently carries out

maintenance of the scheme. The rigorous assessment of available resourcing for

maintenance concluded with funding through a commuted sum taken from the

developer was agreed. A figure of £250,000 allocated for 25 years management

under the current maintenance budget. In reality the need for management input

relative to estimate requirements used is to determine a commuted sum has been

much less (Ashley et al., 2011).

3.3.2 Challenges Faced during the SUDS retrofit

The development of Manor Fields District Park experienced a range of challenges

during the initial stages of construction and site operation led to poor initial water

quality performance. In addition, poor ground caused a swallow-hole to open up in

the upper basin that was not repaired for about one year. One of the most significant

challenges stemmed from the socially complex site context in a socially deprived

area. These problems included vandalism, dumping and burning of cars that were

considered detrimental to the SUDS scheme. These early stage issues were

overcome through incremental stages of design to mitigate against vandalism that

included boulders act as seating; sculptures are used as educational boards

designed by local youth groups. This was in partnership with activities to encourage

a sense of ownership and community spirit:

Education: A programme for local youth groups was created to as a medium

of education in terms of SUDS, and as a part of prevention of any anti-social

behaviour

Interaction: Leisure activities such as pond dipping and feeding waterfowl are

facilitated by the very gentle slopes (1:20) allowing entry to the water.

Social events: Aim to create a sense of community ownership and pride in

the District Park, an annual event celebrating young people’s participation and

the development of the Park is hosted.

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Consistent with the goal of creating an attractive, naturalised stormwater

management system the Parks Development Team implemented a SUDS

Champion. The project endured significant delays through the a culmination of

factors including legal negotiations and bad seasonal weather, the officer aided the

capital works delivery by offering additional on-site supervision, SUDS education to

stakeholders and the necessary impetus to see through the challenges that were

faced (Kennedy et al., 2007).

3.3.3 Stakeholder engagement of the SUDS retrofit

Essential to the successful implementation of the SUDS scheme was the approval

and support by a number of stakeholder groups including landscape architects,

planners, Sheffield Wildlife trust, Land Drainage Authorities, land owners and

Yorkshire water. This added significantly to the regeneration of the area, creating an

inspiring, safe and welcoming quality space for residents and visitors alike (Kennedy

et al., 2007).

3.3.4 Costs of the project

The redevelopment of Manor Parks Field utilised a short time framework to enable

construction to start in 2002 and finish a year later. The total cost for capital works at

the time was £200,000 and the commuted sum was £250,000 (Ashley et al., 2011).

According to Ashley (2001), as the cost of the park maintenance are combined with

the SUDS maintenance, it is difficult to precisely calculate costs. However, an

estimate of £3000 pound per year is likely based on proportions relative to the rest of

the park and the need for small scale remedial work.

3.3.5 SUDS retrofit success factors

As noted, the functional design of the SUDS retrofit utilises the sites natural

characteristics mimicking that of a riparian corridor. The park contains a range of wild

spaces in addition to innovative landscaped areas. The park is greatly valued as an

amenity space where there are plenty of opportunities for children to play (CIRIA,

2014). The site has over 4km of footpaths, as well as smaller paths in order to

encourage exploration of the wilder, hidden areas. The recent completion of a formal

‘Gateway’ now connects the park via good public transport links to the whole of

Sheffield making it truly a Regional Park and not just for one for local people (LI,

2014).

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The scheme illustrates how an alternative approach can be taken to great

advantage. As a summary the Park project has been able at minimal cost to:

Reclaim 2 hectares of land to improved landscape

Construct an events arena / recreational space in the form of a storm basin on

difficult topography

Enhance the wetland ecosystem of the site

Bring extra management finance into a Park

Provide an engagement/educational opportunity for all the community which

could promote ownership

The benefits to all stakeholders show that SUDS can offer opportunities not usually

associated with stormwater management including finance to public project

environmental enhancement, community rehabilitation and visual interest (CIRIA,

2014). The SUD System’s first challenge came during the floods of summer 2007 in

Sheffield, the scheme successful in reduced impact on the River Don through

detaining runoff during the large storm event (LI, 2014).

Manor Fields was designed adopted the SUDS Triangle , as such the scheme has

the fulfilled sustainability objectives and much wider evolved much more than initially

expect (Kennedy et al., 2007).

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3.3.6 Manor fields missed opportunities

After analysing the literature available in review of the case study it is important to

cite The Manor Fields District Park as a ‘missed opportunity’ to create a SUDS

exemplar. As the case study had already constructed most of the drainage networks

before SUDS were considered sustainable drainage were not feasible at source

control. Therefore this SUDS design should be considered an exemplar retrofit

solution rather than a new SUDS exemplar (LI, 2014).This view is also highlighted by

Kennedy (2007);

“the environmental principle of subsidiary has not been fully embraced the scheme is

not a ‘SUDS exemplar’ but an end of pipe retro-fit” (p430).

In hindsight, there was a prolonged period during initial stages of planning where

source control was a rational perspective. The Sheffield Wildlife Trust promoted a

feasibility study of three possible SUDS sites in South-East inner-city Sheffield in

recognition of the development of Manor Fields. The document was produced early

enough to be considered by housing developers when setting out to establish a

drainage solution. Despite the emphasis placed on SUDS as an available technical

solution, it was not recognised during the initial planning proposal (Kennedy et al.,

2007).

Ultimately, the challenges to re-submission a planning application to integrate SUDS

source control measures would have been an irrational perspective for the land

developer, especially after the initial duration and expensive stages of land purchase

and development planning.

3.3.7 SUDS retrofit devices utilised

The SUDS system comprises of a conventional piped system within the housing that

outfalls to three biodiversity basins with a subsequent large level grass space

(events area) for large storm events (three to one prevent) (Ashley et al., 2011)

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3.4 Summary of the case studies main findings

Three of the case studies listed provide good examples of projects that demonstrate

the feasibility of SUDS retrofits. Each case study demonstrates the strong national

and local environmental policies that have shaped the future stormwater

management agenda (as seen on figure 3.8). Policies embrace new development

and regeneration as a way to display the city’s environmental agenda, instead of

viewing development as a threat to green space. Each scheme can be viewed as

much more than a drainage solution as they provide an example of a step toward

urban regeneration as part of sustainable development.

Figure 3.8: A parallel approach of interactive implementation of SUDS retrofits

(Stahre et al., 2003; p19) Each case study had scenarios through planning to implementation of unique

challenges to overcome. However unique the scenario each case study shared the

same philosophy to overcome the challenges:

Early Engagement with stakeholder

Public Consultation

Flexible Designs teams

Resilient designs for future adoption

SUDS Champions

Ownership from local communities

A shared agreement on maintenance

(Please see the case study for Vogelwijk, Den Haag in Appendix B)

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3.5 Discussion

The research findings of Chapter 3 demonstrated that there are a myriad of issues

affecting the use of the SUDS when a retrofit is implemented. This section

discusses the key emerging themes as seen in the literature review chapter and the

research findings chapter. The three areas considered in the comparative study

have similarities that allow for the comparison of the results.

All three areas were of medium to lower socio-economic status within suburban

areas of the large multinational cities: Malmö, Sheffield and Den Haag. The areas

selected were all affected by flooding and there was an urgent response needed for

stormwater management techniques put in place. As a response to flooding issues,

retrofitted management options had been explored and implemented.

The comparison of the results not only indicate similarities in methods of

implementation in storm water drainage but also assist in providing conclusion and

trends on determining best practice for SUDS retrofits. A common outcome in all the

case study areas was the clear perception towards natural looking schemes, with

high aesthetics, amenity, and recreational value. The importance of public

consultation prior to construction has been shown to increase acceptability of the

applied schemes. In all the areas, participants were most willing to express their

ideas and concerns of the applied scheme. They were pleased to participate in the

planning process as they are the ones who live with the new schemes and most of

the time they have already thought of ways to improve their surroundings.

An unexpected outcome was that the transition time involved in migrating from

traditional approaches to a sustainable concept was very high. The institutional

barriers between the different stakeholders involved in the planning and

implementation of the facilities often are unexpectedly high. Certain risks will always

be involved with new approaches to planning. However, the case studies above

justified the use of innovative approaches to create sustainable drainage systems.

The areas have achieved many benefits above and beyond expectations. The

initiative and enthusiasm of the local authorities to overcome barriers endured due to

strong leadership and cohesive professional networks.

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CHAPTER 4. RETROFITTING SUDS: APPLYING RESEARCH MODELS TO THE

STUDY AREA

“SUDS require an understanding of how water behaves naturally and how

engineered structures can be integrated into an attractive and useful landscape

setting”.

-Bray (2011)

4.1 Introduction

Chapter 4 sets out to implement models learned from previous chapters and apply

them to Glasthule village. The West Pier catchment has been chosen as the study

area and Glasthule village as the chosen site. Glasthule village has been prone to

historic surface flooding with high flows in the CSO causing unsatisfactory

intermittent discharge (UID) of effluent into the coastline of Dun Laoghaire. This was

largely attributable to pressure on drainage system from the built up environment

and has been earmarked for remediation work by Dun Laoghaire Rathdown County

Council. The research model introduces an alternative method and design to

drainage in Dun Laoghaire not yet being used to date.

4.2 Methodology for applying models to Glasthule village, South Dublin

The following methodology is a sequential process influenced by guidance, literature

and case studies from the previous sections. A desk study and field survey was

carried out in the West Pier catchment as a means of identifying the areas historic

and present drainage characteristics.

The data gathered, in relation to the study areas key drainage characteristics were

used to develop a number of map overlays. This assisted in identification of

perceptual qualities of the study area and established the drainage elements current

condition.The maps and information gathered were utilized in a sieve mapping

process to determine the most suitable area for SUDS retrofits. The areas were

further explored through the process of a SUDS scorecard. Each area chosen will

have SUDS measures applied that provide opportunities for drainage enhancement.

.

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4.3 Applying lessons learned to Glasthule village, South Dublin

The chosen models that will applied to Glasthule village derive from the literature

review which highlighted two frameworks for retrofitting SUDS advocated by Ashley

(2011) and Stovin (2006) (sections 2.3.1.2 and 2.3.1.3). The first framework provides

transparency in identifying methods and procedures that can be utilised to provide

the location, size and structure of SUDS retrofit techniques that are the most suitable

for the study.

Figure 4.1: A framework for retrofitting. (Ashley et al., 2011; p38)

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The design should start by following the SUDS philosophy, which calls for the

inclusion of:

1. SUDS on the surface: where possible, SUDS should be used on the surface as

much as possible.

2. A management train: using several SUDS components in series.

3. Source control: managing runoff as close as possible to where it falls as rain.

4. Sub-catchments: characterising areas into land use and drainage type.

4.4 Preparation of the scoping process

In line with the retrofitting framework, the following section establishes the drivers,

potential partnerships that should be integrated from the beginning of the procedure.

4.4.1 Establishing the need and drivers for change

In recent years, Glasthule village has been severely flooded in two major recorded

rainfall occurrences in a small geographical area, resulting in, pluvial flooding, which

was impossible to accurately forecast in advance (RPS, 2009). The study ares

drainage network is typical of an urban area in Dublin, constructed in the 19th

century. The combined sewer network has subsequently, due to heavy downfalls

and increased development, resulted in drainage capacity issues and diffused

pollution that affects watercourses and water quality (DCC, 2005). Prior to

urbanisation, open channels streams and ditches drained the area naturally (RPS,

2012).

Glasthule village currently has no SUD schemes and the Dun Laoghaire Rathdown

Local Authority have tackled the problem by upgrading the sewage capacity. During

heavy rainfall, the sewage is allowed overflow into the coastline through a combined

sewer overflow (CSO) outfall. At present, a local dilapidated swimming baths is

under re-development by Dun Laoghaire Rathdown County Council (DLRCC) (RSP,

2012).

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Figure 4.6: Flood events in Glasthule village (RSP, 2009; 7-10)

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The redevelopment has prompted an extension on the current combined sewer

overflow waste pipe that fails to recognise the issue of diffuse water pollution. In

order to improve environmental performances of the catchment area the study

therefore must:

Reduce spillage volumes and frequency at the West Pier short sea outfall;

Reduce spillage volumes and frequency at the Newtownsmith Emergency

Overflow;

Reduce spillage volumes and frequency at the West Pier and Bulloch long

sea outfalls

4.4.2 Establishing potential partnerships

As seen in the case study of Augustenborg (section 3.2, p63) the effective

partnerships between the housing company and the municipality were beneficial and

essential in delivering the retrofit. This is appropriate for all retrofit schemes,

irrespective of scale. Partners are defined as those responsible for being involved in

or taking decisions and actions. These are most likely the organisations which fund

the construction and maintenance of measures (Ashley, 2011). Listed below are a

number of potential partners and stakeholders that could assume a role in the

retrofitting project in Glasthule village.

Table 4.1: Examples of the potential partners or stakeholders bodies in a retrofitting SUDS project in Glasthule

(Adopted from Ashley et al., 2011). Type Organisation

Partner Environmental Agency (Ireland) Department of Environment, Community and Local Government Dun Laoghaire Rathdown County Council (various Departments) Irish Water (recently formed) Irish Heritage Council

Partner or stakeholder (in addition to the above)

Regeneration Agencies (Dublin regeneration) Developers Riparian Owners Road Services

Stakeholders (includes both categories above)

Action Groups Community Groups Individual members of the public Landowners Parish Councils Local flood risk management partnerships

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The role of partners and stakeholders vary through the project. Those within the

partnership could include those who are linked with key drivers and opportunities.

Funding and resources should also be sought from each stakeholder to oversee the

study, project completion and to consider who eventually will operate and maintain

the project.

4.4.3 Early engagement objectives

An early engagement plan to support the potential for retrofitting irrespective of scale

should be developed jointly with partners. It is important that opportunities and

challenges are clearly defined from the outset.

4.4.4 Scope of the retrofit study

At this stage, it is important that the spatial scale of the study is identified. In order to

lower volume of CSO spills and subsequent flooding in Glasthule village a catchment

based boundary is identified .The data could help in understanding the challenges of

holistic catchment management, diffuse pollution, and the “linking scales” in the

SUDS treatment train.

Figure 4.7: Scope of retrofitting to the West pier catchment

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The 'strategic' approach is initially set to identify areas that are suitable for a SUDS

retrofit. Thereafter, an ‘opportunistic’ approach will be applied to Glasthule village in

order to represent different sustainable drainage techniques and different types of

areas available for development and regeneration. Though Glasthule village is a

reasonably small area, the strategic scale identified can enable a coherent retrofit

opportunity.

4.5 Applying the feasibility study to Glasthule village

At this stage it is important to recognise that the feasibility of a retrofit scheme should

demonstrate how SUDS can mange flood risk, improve water quality to receiving

waters and create wider benefits. This feasibility study aims to recognise sites that

are suitable for SUDS. The following tasks were undertaken:

Site identification

Feasibility assessment of site deemed most suitable a SUDS retrofitting

An important factor at this stage is the need to identify sites which would provide

improvements to CSO performance and what context would be applicable for SUDS.

4.5.1. Site selection criteria one

The site selection process employs a methodology based upon criteria set out by

Stovin (2003) and adapted by Atkins (2004).As seen on Figure 4.8 the hierarchical

structure favours individual landowners for retrofitting, where sites such as

institutional roofs and car parks are targeted.

Figure 4.8: Site Preference for SUDS

(Atkins, 2004, p9)

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Ashley (2011) advocates the twin-track approach of retrofitting SUDS that applies

‘strategic’ and ‘opportunistic’ methods of recognising potential SUDS opportunities

(section 2.3.1.2). The ‘strategic’ approach will apply a larger scale assessment of

the West Pier catchment where retrofitting should be appropriate and will utilise a

sieve mapping process. The ‘opportunistic’ mapping will implement small scale

changes to Glasthule village using Stovin’s (2003) decision support map. It should

be stressed that the methodology developed has been specifically tailored to meet

the objectives of the project, subject to the constraints, and therefore has inherent

limitations.

4.5.1.1 Existing catchment characteristics

The study area is located on the coast of South Dublin, approximately 12 kilometres

from Dublin City centre. The catchment topography drains north-east from the

elevated undeveloped hills of Dalkey and Killiney and converges in Glasthule Village.

The land-use is dominated by residential areas with a small percentage of industrial

estates, with high levels of impermeable surfaces. As mentioned previously, the

drainage system dates back to the 19th century and is made up of a combined

sewerage and surface water system.

Figure 4.9: Map of catchment area: Sub catchments

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4.5.1.2 Pre-development drainage systems

As indicated in Figure 4.3.1 prior to urban growth, Glasthule village located in the

West Pier catchment was naturally drained by open-channel streams and ditches.

One of the most recognisable watershed features of the West Pier Catchment was

the Glasthule stream (marked by the blue line).

This channel represents the main hydraulic corridor for the surface water. The map

indicates Glasthule Stream rising in the area of present day Sallyglen Road and

flowing in a north-easterly direction, largely to Adelaide Road before discharging to

the sea via Scotsman’s Bay, the seafront of Glasthule Village.

Figure 4.10.1: Map of catchment area (Taylor, 1816). Glasthule Stream highlighted

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Figure4.10.2: Map of catchment area 1937.Glasthule stream Highlighted

As highlighted in figure 4.10.1 and 4.10.2 the hydraulic nature of the Glasthule

stream has changed drastically from 1816 to 1937 as urbanisation progressively

modified the landscape. The progression from a riparian corridor to a linear

engineered culvert is highlighted above. This is a result of the increase in

urbanisation.

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4.5.1.3 Present day open channels and watercourse

In addition to large scale residential development, other significant factors have

resulted in the almost complete removal of the open water channel stream system

including:

The construction of the Dublin-Wexford Mainline on which the DART services

also run at a depth of 6m surrounding ground level across the study area,.

This crosses the natural flow path of the stream.

The development of several areas for quarrying, in particular on Dalkey Hill

during the 19th Century (RSP, 2012).

Presently there is little evidence of the Glasthule stream. A small section of open

channel exists in a private residence, however it is difficult to ascertain whether it is

actually the original path of the Glasthule Stream. The section of the stream in

question, and all parts of the stream that existed historically, now drain into the

present day sewage system (RPS, 2009).

Figure 4.11: Interpolation of pre-development open watercourses using historical

maps.

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4.5.1.4 Groundwater springs

Within the study area there are records of a number of groundwater springs. Figures

4.12 captured during the flooding of 2009 indicates surface water flows along the

DART line after heavy precipitation in the Glenageary Train Station area: flows along

the track at Glenageary discharge to a large combined sewer culvert beneath the

tracks at Adelaide Road. (RPS, 2012).

Figure 4.12: Railway line during groundwater flooding

(RSP, 2009; p8)

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4.5.1.5 Surface water drainage systems and separate foul

As indicated on figure 4.13 below are the area’s most recently constructed infill

developments that contain a separate surface water drainage system that presently

discharges to the combined sewer network. In addition, Figure 4.13 indicates

undeveloped areas of known significant stormwater input- these include the disused

quarry on Dalkey Hill, which has on occasions discharged significant quantities of

stormwater downstream.

Figure 4.13: Separate drainage & undeveloped areas and open space connecting to existing combined sewers system

4.5.1.6 Sewer network performance Glasthule village and Newtownsmith

Two main sewer lines converge at the Adelaide Road overflow chamber, just

upstream of Glasthule Village. The first, a 950mm x 600mm sewer, crosses beneath

the DART tracks at Adelaide Road Bridge and runs down Adelaide Road to the

overflow chamber. The second, a 1200mm pipe, runs from Castlepark Road

overflow chamber to the Adelaide Road overflow chamber. Both Adelaide Road and

Castlepark Road overflow chambers have a steel plate across the outgoing pipe.

Both plates, which were set at approximately 350mm above the invert of the pipe

upon installation, have never been adjusted (as shown on figure 4.14.1).

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Figure 4.14.1: The plate Castlepark Rd.

These plates were installed with the purpose of limiting forward flow to West Pier

Pumping Station. During normal dry weather flow (DWF) days, all flow entering these

overflow chambers travels forward to West Pier (through the sewers highlighted in

red on Figure 4.14.2). However during storm events, with the plates limiting the

forward flow from the chambers to West Pier, a large proportion overflows to Bullock

Pumping Station (via the sewers highlighted in blue in Figure 4.14.2).

Figure 4.14.2: Key Drainage Infrastructure

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4.5.2 Confirming the needs

Confirming the needs of a SUDS retrofit project collates all data on the West Pier

catchment and Glasthule village to this point. Problems are then broken into two

categories, the causes and the effects, of flooding and CS overflows. As a method

of establishing the link between peak flows from its beginning (source) to where it

causes flooding (receptor).

Table 4.2: Linking potential causes with the effects: Source-Pathway-Receptor

Location and typical cause of the problem

Typical effect seen

Flooding Pollution No sewer capacity

Health risk

Water demand

Source Surrounding Catchment

Too much surface runoff

Too much surface runoff in below ground system

Pollutants in surface runoff

Wastewater in surface outfalls

Surface water in foul pipes

Lack of water resource

Lack of amenity/biodiversity

Pathway West Pier Sewage line

Inadequate system capacity

Local throttle/blockage in system

No control on flows from major to minor systems

Wastewater in surface water

Lack of amenity/biodiversity

Receptor Glasthule village

Too much flow from upstream system

Vulnerable buildings

Lack of individual buildings/ resilience

Lack of amenity/biodiversity

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4.5.3 Opportunities for retrofitting- West Pier Catchment, Dun Laoghaire

Case studies have shown that experiences of retrofitting SUDS techniques are more

straightforward in some areas than others. ‘Strategic’ retrofitting is based on

research in the literature review (2.3.1.2, p45) which advocates three categories:

target, common and future.

Figure 4.15: Opportunities for retrofitting SUDS

Extensive research and baseline data gathered has been identified to create an

understanding of the study area and its relevant surrounding areas in their current

condition. The data shown on figure 4.9 has been created to convey the study areas

current make up when analysing its physical and natural infrastructure. Sieve

mapping overlays and collates data gathered that analysis areas that have the

potential options for retrofitting. Following this stage of identifies another sieve map

will provide further scrutiny in an iterative process.

When prioritising areas for retrofitting, the areas highlighted below on table 4.6 had

targeted areas with a low number of landowners, separate drainage systems and a

suitable topography for retrofitting.

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Table 4.3: Opportunities for retrofitting in Glasthule. Target-Common-Future mentioned in Figure 4.15

(source: author) Opportunities No Area Description

Target- large proportion of surface runoff can be removed from and existing drainage system, or detained in storage, with minimum new infrastructure

1a Dalkey Quarry Disused granite quarry

1b Sallyglen Road Separate drainage system adjoin housing estates

1c Glasthule Playing fields

A disused community playing pitch

1d Newtownsmith Coastal green space amenity

1e Eden Park Green space at the beginning of Glasthule

1f St. Catherine’s Rd

Residential area prone to flooding

Common-Individual plots across estates offer an opportunity to standardise measures across the area

2 Catchments Residential Areas

Thirteen residential areas with separate drainage systems

Future- part of a wider work programme (e.g. Regeneration or adaptive drainage measures).

3 Hyde Park Playing pitches with a separate drainage system that intersects a stream culvert

The research shown indicates that opportunities to retrofit SUDS can be applied to a

diverse scale of area. As the case studies show, it is also important to recognise the

power of public engagement at this stage .Community engagement helped identify

strategies while boosting community confidence in the retrofit project (section 3.2.7)

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4.5.4 Matching opportunities with needs

This section sets out a staged approach to identify strategies for retrofitting, which

matches the needs (section 4.6.4) with the opportunities (section 4.6.5). A strategy

describes a particular type or category of measure without defining the detail of

individual measures, that are possible candidates for construction (following detailed

design).

Table 4.4: Strategies to address problems at the Source-Pathway-Receptor

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4.5.5 Site Selection Matrix- Glasthule village

This section represents a specific intervention based around source control of a

SUDS retrofit. The approach advocated by Stovin & Swan 2003 is an approach that

considers an alternative decision-making option for SUDS retrofits. This hierarchy

suggests that the first option to be considered should be regional site controls aimed

at treating the end-of-pipe discharge from sewer systems.

Figure 4.16: Breakdown of landtake in Glasthule

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4.5.6 Anticipated constraints

As the retrofitting assessment is at a catchment based scale it is necessary to

understand the practical issues affecting implementation of SUDS measures at this

scale.

Due to the limitation of the research in providing soil conditions for each site it is

anticipated that poor infiltration conditions in some areas would mean that the

retrofitted SUDS would be reliant on storage to achieve greenfield runoff rates. In

locations with more favourable infiltration conditions a wider range of retrofitting

options exists. The stormwater management benefits associated with infiltration

systems are likely to be greater, as flows and pollutants are removed rather than just

attenuated systems.

Consideration of constraints, at an early stage, can mitigate against incorrectly

retrofitting SUDS to an area and identify any opportunities (Ashley et al., 2011).

Constraints are managed best as part of an iterative design process that should be

continually revisited. The issues are demonstrated in section 2.3.1.4 and highlighted

below:

Groundwater levels and source protection zones:

Contaminated Land

Environment and ecology

Restricted sites

Sensitive receiving waters

Catchment topography

Location of utilities

Urban Design

Engagement

Health and Safety

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4.6 Developing SUDS retrofit options

In an effort to identify options for developing a SUDS retrofit, this section builds upon

the feasibility work to determine a flexible approach and appropriate measures within

the context. Measures of SUDS will be assessed through a scorecard assessment

as a means of identifying the accurate context.

4.6.1 Retrofit option planning

As part of the SUDS retrofit project in the study area, it is important to consider the

natural flow routes across the catchment area and how measures link together.

Across the catchments the contours show it would fall from the north-west to the

south-east of the area and this is the general flow route that is adopted in the SUDS.

Measures will be illustrated as a graphic representation that only is meant to be used

as an option of adoption. The proposed measures will integrate and improve the

public realm that recognises the potential for multiple usage space as an asset.

4.6.2 Considering space and selecting retrofit measures

There are many SUDS techniques available for retrofitting which fulfil the same

function; some will be more applicable than others. Due to the scale and nature of

measures, a score card assessment has been applied (adapted from Ashley, 2011)

as to screen measures promptly (Table 4.8 below). Tables (5.2 & 5.4) assisted as a

method of understanding the potential benefit/constraint of each measure and

common opportunities for similar scenarios.

Table 4.5: Scorecard for SUDS assessment Area Criteria SUDS

Swale Bio Retent

P-pave.

Det -Basin

Inf-Basin

Pond Wet land

G-roof

W- Butt

Geo cell

Sand Filters

Filter Strips

Dalkey Quarry

Performance

Technical- P

Technical- R

Adaptability

Acceptability

Economic

Affordability

Social

Environment

Key Drivers

Score 10 U -15 8 -6 2 14 U U 9 U 0

(Please see Appendix F and M for further expansion)

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4.6.3. Retrofit measures- West Pier catchment:

4.6.3.1 Proposed retrofitting SUDS at Dalkey Quarry

Figure 4.17: Proposed constructed wetland for Dalkey Quarry

Previously flooding is understood to have occurred on Ardburgh Close as runoff

generated by Dalkey Quarry area spilt onto Ardburagh Road. By analysing Figure

4.18.1 it is clear that the levels are a major factor in runoff generation. A runoff

attenuation system, through land designed in the basin of the quarry can form a

wetland/marshland to mitigate against further flooding. This will increase the

biodiversity in the area along with increasing the landscape amenity.

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4.6.3.2 Proposed retrofitting SUDS in Sallyglen Road

Figure 4.18.1: Proposed retrofit for Sallyglen Road

Introducing a SUDS proposal for Sallyglen Road and Park which include the housing

estates of Park Road and Glenageary Lodge would significantly reduce downstream

pressures on sewage systems in Glasthule village. The proposal would apply a

treatment train suds system of swales, permeable pavements, detention ponds to

control water at source point. From there, water would attenuate into a large

detention basin that would provide amenity and biodiversity. A dry detention would

manage exceedence flows during extreme rain events.

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4.6.3.3 Proposed retrofitting SUDS St. Catherine’s Road

Figure 4.18.2: Proposed retrofit for St. Catharine’s Road

A further option for retrofitting SUDS, as indicated on figure 4.18.2, is the separation

of the two piped flows from drainage in the St. Catherine’s area. Retrofit measures

best suited from the score card analysis indicate that street side bio retention strips

and open channel rills could be easily implemented, as it is a residential area with

wide roads and low traffic. Permeable paving would run along the footpath

horizontally with a linear swale to manage excess flows during heavy precipitation.

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4.6.4 Retrofit measures- Glasthule

Figure 4.18.3: Proposed retrofit for Glasthule village

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At the beginning of the research, Dun Laoghaire Rathdown County Council highlight

that a SUDS retrofit in Glasthule was not possible due to its built up nature. (Due to

the built up nature of Glasthule village there were limited. However, though the

‘opportunistic’ approach advocated by Ashley (2011) found that there were

significant prospects of attenuating stormwater through SUDS retrofits in areas

previously unconsidered. The main areas of retrofitting will be considered in further

detail below:

Eden Park

The retrofitted SUDS measures used in Eden Park share a similar context as

Sallyglen Park resulting in both having measures that are alike. The existing setting

of Eden Park enabled a large central pond measure to be implemented which is fed

by the surrounding permeable car park.

Newtownsmith wetland

The wetland is the largest single SUDS measure implemented within the study area,

this required as the wetland is required to hold the most amount of exceedance

during heavy flow. This will create a drainage system separate of the CSO that

mitigates against flooding. As most of Dublin’s coastline was a brackish wetland in

historic times, the SUDS measures could be considered a restoration creating a new

sense of place to the area. The potential water cleaning attributes are listed below:

Glasthule village

The measures applied to Glasthule village are applied as part of the ‘oppertunistic’

approach and ‘nibble’ at small pieces of unused landscape. The flood risk would be

completely mitigated against using a green roofs initially to capture 90% of water, as

seen in Malmo. The wide roads would be narrowed to a minimum of 6m in width to

accommodate for street side bio-retention strips.

Listed below are a number of advantages and disadvantages that retrofitting SUDS

measures may face:

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Measure Advantages Disadvantages Pollutant removed

Bio retention strips /Street Side

Very effective in removing urban pollutants

Can reduce volume and rate of runoff

Good retrofit capability and Flexible layout

requires landscaping and

management

susceptible to clogging if surrounding landscape is poorly manages

Bacteria, Viruses Total suspended solids (TTS) Cyanide Chlorides Metals Hydrocarbons Pesticides

Detention ponds

Can cater for a wide range of rainfall events can be used where groundwater is vulnerable, if lined simple to design and construct.

Potential for dual land use.

Easy to maintain.

Little reduction in runoff volume.

Detention depths may be constrained by system inlet and outlet levels.

Total suspended solids (TTS) Bacteria, Viruses Pathogens Nitrogen, Phospherous Pesticides

Swale and Dry basins

easy to incorporate into landscaping

good removal of urban pollutants

reduces runoff rates and volumes low capital cost

Not suitable for steep areas significant

Not suitable in areas with Roadside parking

Limits opportunities to use trees for Landscaping

Total suspended solids (TTS) Bacteria, Viruses Pathogens Nitrogen, Phospherous Pesticides

Permeable paving

effective in removing urban runoff pollutants

significant reduction in volume and rate of surface runoff

good retrofit capability

Cannot be used where large sediment.

current practice is to use on highways with low traffic volumes, low axle loads and speeds of less than 30 mph

Bacteria, Viruses, Pathogens Nitrogen, Phospherous Pesticides

Green roof Mimic predevelopment state of building footprint.

Good removal capability of atmospherically deposited urban pollutants.

Can be applied in high density developments.

Cost (compared to conventional runoff.

Not appropriate for steep roofs.

Opportunities for retrofitting may be limited by roof structure (strength, pitch etc).

Pathogens Nitrogen, Phospherous Pesticides

Wetland Good removal capability of urban pollutant.

Good community acceptability.

High benefits to ecology, aesthetic and amenity

Land take is high.

Requires baseflow.

Limited depth range for flow attenuation.

Bacteria, Viruses Total suspended solids (TTS) Cyanide Chlorides Metals Hydrocarbons

Open rills Easy to construct and low construction cost.

Easily integrated into landscaping and can be designed to provide aesthetic benefits.

Encourages evaporation and can promote infiltration.

Not suitable for draining hotspot runoff or for locations where risk of groundwater contamination, unless infiltration is prevented.

No significant attenuation or reduction of extreme event flows.

Not suitable for steep sites

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4.7 Appraisal of the SUDS retrofit project

Appraisal of a project requires an estimation of the benefits against the cost of such

measures. The research looked at models for Cost benefit Analysis (CBA) for SUDS

retrofits. However, there were limits to the study as not enough data could be

gathered in order to demonstrate a CBA. However, as shown throughout the

research (Chapter 2 & 3), there can be significant long term savings to be made in

retrofitting SUDS compared to conventional drainage. Especially when considered

as part of a multi-value approach. To this end the multiple benefits which are

included in proposed measures, provide an overall improvement to the environment

of Glasthule village.

4.7.1 Assessing the benefits and costs involved in the retrofit project

It is important to recognise the benefits that are involved at this stage of the project

even though the research has already stated such benefits. From the initial stages of

research, the main objective of the study was to improve water quality in Glasthule

village through substantially reducing CSO flow levels. In order to achieve this, it was

recognised that an analysis of the West Pier catchment and Glasthule has been

undertaken and an extensive number of options for retrofitting SUDS.

These options have been considered to provide a permanent flood mitigation

measure that will reduce risk in the long term. Mitigatory measures, which will

include recommendations for substantial extraction of surface water drainage from

the combined sewerage system, as part of the ongoing Glasthule village flood &

Sallyglen road to Newtownsmith surface water separation plan. Benefits from these

measures could include:

reducing peak flows to sewers and potentially reducing the risk of flooding

downstream

reducing volumes and the frequency of water flow

improving water quality over conventional surface water sewers by removing

pollutants from diffuse pollutant sources

reducing potable water demand through rainwater harvesting

improving amenity through the provision of public open space and wildlife

habitat

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replicating natural drainage patterns, including the recharge of groundwater

so that base flows are maintained.

.

Due to a lack of detailed cost information a complete CBA cannot be undertaken .

However in the case of Malmo the benefits of SUDs far outreached costs invested.

Between investors 24 million euro was financed for Augustenborgs redevelopment.

As shown in section 3.2.9, there are a multitude of tangible and intangible benefits

from the adaptation of the Augustenborg area summarised below:

Biodiversity in the area has increased by 50%.

The environmental impact of the area decreased by 20%.

The participatory character of the project sparked interest in renewable

energy and in sustainable transport among residents

Turnover of tenancies decreased by 50%, unemployment fell to 6%,

participation in elections increased from 54 % to 79%.

The regeneration of Augustenborg brought three new local companies: Watreco AB

(set up by local resident and amateur water enthusiast), the Green Roof Institute,

and the car pool established in 2000, which uses ethanol hybrid cars to further

reduce environmental impacts. Augustenborg as an example indicates how

implementation of SUDS measures can have far outreaching benefits that create

employment, biodiversity and amenity space.

4.8 Implementation of SUDS retrofit options

The implementation stage includes detail design of retrofitting measures selected,

secured funding and future ownership and management of maintenance which can

run concurrently through the projects life cycle.

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4.8.1 Planning the retrofit measures

Following the initial phases of engagement and site selection the project would then

be taken to detail design and construction. Pre and post construction monitoring

would need to be carried out on a regular basis in order to assess benefits and in

terms of CSO improvement. At the project inception, the following tasks would need

to be undertaken:

Progress detailed design at sites selected for construction;

Obtain owner /stakeholder permission and develop planning

application/consenting procedure;

Prepare contracts, documents and initiate tendering procedure for the

appointment of contractors;

Undertake pre and post-construction monitoring at sites to be developed;

Plan and finance long term operation and maintenance

Prepare accurate as-built information of measures

It is most important to ensure that key synergies are developed and maintained

between the main parties. This was a key method of implementing such changes

when retrofitting Augustenborg. It took nearly ten years for the framework Malmö

now has in place to be adopted.

Figure4.19: Key synergies and implementation

(Stahre, 2003)

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4.9 Performance monitoring

Guidance set out by Ashley (2011) advocates utilising common measures that make

up part of the assets of a management strategy. It is also a way of abiding by the

Water Framework Directive. In Augustenborg maintenance is jointly funded through

residents rent, the water board through the water rates, and the city council’s

standard maintenance budgets.

4.9.1 Monitoring and evaluating the approach

If the retrofitted changes were implemented to the study area it would be an

exemplar for Irish drainage. As not every measure would necessarily be completely

successful for all the areas and may need adjusting. It would be important the SUDS

retrofits would be monitored and lessons are learned from failings and the measure

is adjusted accordingly. This would then serve as a lesson for other SUDS retrofits

across Ireland.

4.9.2 Gaining experience

Experiences from case studies (chapter 3) show that monitoring can be a method of

building confidence in stakeholders who will eventually adopt and own a SUDS

measure. It is also a method of evaluating performance that can promote SUDS

uptake and is a mode of interacting with sceptics in the public domain and local

authorities. Five main reasons behind monitoring in the West Pier catchment would

be:

Confirming the effects and benefits on the receiving waters and local

environment

Learning about maintenance requirements

Improving operational protocols

Providing evidence to improve implementation techniques

Provide evidence of growing public acceptance and views on benefits and

risks

As the retrofitting project is implemented across a catchment scale it would be

beneficial if stakeholder and partners informed the public regarding access and use

of SUDS sites, as a method of promoting SUDS and increasing awareness around

water.

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4.9.3 What to monitor in SUDS, what to assess and why?

When developing a monitoring plan for such a large area it is important to outline

which sites are the preferred short term spot sampling and long term assessment

sites. The plan must also outline aims, approach, method, equipment, costs, time

necessary and benefits of such measures. An integrated approach to monitor and

maintain SUDS measures is a scenario that would benefit partners involved in SUDS

education and stakeholders. It is also important that on such a scale that the below

options are considered:

Assessing against the original objectives

SUDS performance

Wider benefits

Successful ownership & Local engagement

Maintenance improvements to be developed

4.9.4 Collate data and learn through sharing

Sharing and learning from monitoring would form a vital part of achieving a

catchment base of the study area. This is a powerful tool in Vogelwijk where local

stakeholders share information via a website and facebook page in order to share

knowledge and improve understanding. Partners could implement this initiative to

enable improvements to the retrofit process and implementation.

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CHAPTER 5. CONCLUSIONS AND FUTURE RECOMENDATIONS

“We all need space; unless we have it, we cannot reach that sense of quiet in which

whispers of better things come to us gently”

Octavia Hill, 1888

5.1 Introduction

This chapter summarises the issues raised from the discussion of findings in Chapter

4 and identifies the main conclusions reached. This research study endeavoured to

find out what issues arose as a result of retrofitting SUDS to Glasthule village to

improve water quality in the area. What has been learned from this study is also

outlined, as are questions and issues which arise from the research, some of which

could be the subject of further research.

5.2 Summary and Conclusions

This study shows through the literature reviewed, case studies and applying best

practice models to Glasthule village that the retrofitting SUDS is applicable and

suitable with significant benefits to its drainage. If the project was realised the area

would see a solution to its flood risk and significantly lower combined sewer overflow

(CSO) spills as seen in the case study of Augustenborg, Malmo (section 3.2, p61). A

contributing factor to the success of the retrofit project of successful design to

Glasthule village and its surrounding was realised through utilising a coherent

retrofitting framework.

The Water Framework Directive has been in place for over 9 years across Europe.

Ireland has seen very limited progress in achieving the required reforms that would

be necessary to meet EU objectives. Planning guidance for Ireland in the Greater

Dublin Strategic Drainage Study (GDSDS), DDC (2006), is supportive of SUDS in

new developments. The planning framework in Ireland is structured a linear manner

to stormwater drainage and does not meet the requirements of SUDS (Stahre, 2003)

(please see section for further detail 2.5.1, p55).

118

The research also identified other weaknesses of the GDSDS in Ireland, listed

below:

A lack of clear guidance on SUDS

No training provided to the engineers who were responsible for the

implementation of the policies

A lack of enforcing SUDS by planning authorities

However, the research demonstrates that these barriers can be overcome through

ensuring key synergies are developed and maintained between the main partners in

SUDS. Education and training was a clear deterrent to implementing SUDS through

the research with there being a real need for a new holistic guidance document on

SUDS in Ireland (Section 2.6, p59).

The literature review provided a number of international examples of successful

retrofits where SUDS have been successful in providing a range of diverse benefits.

Implementation of this approach in practice would be extremely difficult. This is due

to the fact that Ireland’s current regulatory/funding environment appears to promote

‘quick fix’ solutions to urban drainage problems. Retrofit SUDS have rarely been

explored as remedial solutions and when they have been explored; their merits have

generally been assessed against those of conventional solutions using reasonably

‘short-term’ considerations – meaning they are often rejected as being too expensive

and disruptive.

The case studies analysed generally reflect situations where agencies (e.g.

municipalities and housing agencies) collectively work with local communities to

implement innovative solutions. They have not necessarily been constrained to be

cost-intuitive in comparison with traditional approaches. However, the study shows

that retrofitting SUDS is as cost efficient, if not more, cost effective as traditional

solutions without factoring the overall benefits retrofitting SUDS can achieve.

119

5.2.1 Retrofitting SUDS to Glasthule

Several retrofit options were developed for the West Pier catchment serving

Glasthule village. Design options of Sallyglen Park, St. Catherine’s road and Dalkey

Quarry at a ‘strategic’ planning scale were chosen due to the areas separate

drainage system. If implemented the retrofitted SUD systems would contribute

majorly to the surface water at source point and at the receptor. Design options in

Glasthule represent the SUDS at a sub-catchment basis within the cartilage of public

space within Glasthule village. A significant positive, from the finding of work on

design option 4.6.3 was that- from a technical perspective- the use of retrofit SUDS

by individual landowners and potential of large attenuation and detention sites would

be likely to have a positive benefit on the downstream water quality in Glasthule

It is concluded that option 4.6.4 would provide significant improvements to detention

Glasthule village and alleviate the potential of unexpected pluvial flooding. This is

due to the fact that the ‘opportunistic’ nibbling of green space around Glasthule

village that proposes incremental changes to provide lasting drainage benefits. Such

as, Green roofs that offer considerable potential to manage stormwater at source.

There is a prevalence of roofs that could be adapted for the widespread adoption of

green roofs in the catchment that could be explored further. There is also an

opportunity to develop for DLRCC to consider the stand point, where all new

developments in the West Pier catchment consider the installation of green roofs.

New builds cannot meet this target alone, retrofitting SUDS is an ideal way to

implement changes on all scales when updating ageing infrastructure. Glasthule

village has the ideal capacity to act as an Irish exemplar of sustainability in

stormwater such as places like Manor Fields and Malmö have created. Sustainable

urban drainage is a cost effective method where no space is useless that can create

biodiversity, community, environmental justice, jobs and education.

120

5.2.2 Lessons learned from Glasthule village

There were a number of lessons learned during the course of the study that can be

further developed for other catchment based flood relief schemes.

A framework for retrofitting SUDS

The framework emphasised by Ashley (2011) forms a basis for retrofitting SUDS for

the study. It creates an established basis for an iterative planning system that

encourages an integrated design process for SUDS retrofits. The framework works

on different levels of the retrofit spectrum both large scale and small scale where

stormwater is treated as an opportunity rather than a problem. As the study shows, a

collaborative view is hypothesised in order to meet the framework objectives set out.

Overall the method is straightforward and easily adaptable and formed a vital part of

the adoption process when applying SUDS measures to Glasthule’s drainage

system.

Site selection methodology

This study utilised two forms of site selection criteria in the research methodology

process. These came from the analysis which recognised a need for both catchment

level (West Pier) and district (Glasthule village) scale study to achieve necessary

objectives and a coherent design process. There are many opportunities to retrofit

measures and to demonstrate that the design process is applicable and suitable for

use at two different levels. The models applied illustrated how space can be

maximised to have be multi-functional. This approach is maximised if a range of

professions work closely together to provide joint solutions and all interested parties

are involved early on in the process.

Engagement

Throughout the project it was clear that early iterative engagement with a synergy of

multi-lateral professions and stakeholders was an overarching component of

successful SUDS retrofit. In a project like the proposed flood relief scheme in

Glasthule village, this theory could be applied. It could be a completely innovative

way of working in Ireland and would challenge the conceived notion of stormwater

drainage in Dun Laoghaire Rathdown and further afield. Stormwater management

121

may or may not be managed under the new authority of the recently formed state

sponsored company Irish Water

SUDS measure selection criteria- scorecard

The generic scorecard methodology provided a foundation for an easy to use clear

decision making process which allows a transparent method of selecting SUDS

measures. However, this process relies on the applicants experience and judgment.

This method could also lead to discrepancies in the selection of measures but all

SUDS measures can be different in terms of their design and their context, and

some can work better than others. Clearly the scorecard criteria are not a universal

panacea, yet it offers an enhanced selection process for SUDS measures in this

particular area. SUDS retrofits can be successfully implemented if lessons are

learned from previous failures and the measures are adjusted accordingly.

Real world practicalities

Presently there is no overarching guidance on the technical design of SUDS that

Irish expertise can draw on. It should no longer be the major constraining factor. The

study intended to carry out design work for final implementation that aimed to

produce scenarios workable in practices. Issues were raised in light of this such as

stakeholder involvement, land ownership and drivers that should be considered from

the outset of a retrofit project.

5.3 Recommendations in policy and legislation changes

5.3.1 EC Water Framework Directive (WFD)

The Water Framework Directive has been in place for over 10 years across Europe.

As a result, in theory it would be expected that there has been significant changes in

the way water is managed by EU Member States. This is not the case for Ireland;

very limited progress has been achieved in environmental ambition or in the required

reforms in order to achieve sustainable water management. A prime example is

Ireland’s failings to meet any of the targets set out, without any condemnation of

incentives from Europe to correct the path. To improve this European Commission

should execute:

122

Legal avenues more intensively to uphold the minimum requirements of the

WFD.

Work more closely with the competent authorities.

Focus on tangible results, which can change the course of individual

development projects, introduce toxics bans, and have the power to create

political will for reforms.

In order for Ireland to abide by the Water Framework Directive (WFD), it is

anticipated that there will significant pressure to manage stormwater in a new way.

One present theme throughout the research is the lack of presence of clear and well

defined policy regarding stormwater management. This lack of influence has far

reaching implications for stormwater management in Ireland. When developing a

plan to implement SUDS measures it is important to have clear guidelines. If not, as

the case is in Ireland, the ambiguity creates a sense of doubt and enables the

justification of traditional drainage measures. Ireland in particular is facing a

transition period in the way it manages its waters with a significant amount still

unknown regarding stormwater management.

5.4 Discussions and suggestions for further research

It is recommended that additional work is performed to link water quality objectives

for receiving waters to quantitative indicators of performance .i.e. what level of

disconnection is required to enable watercourse to achieve its water quality

objective.

It is recommended that further work be undertaken to establish guidance on SUDS

from a range of perspectives regarding measures and eventually retrofits. It is clear

through the results of the study, that future investigations into guidance would greatly

improve uptake of SUDS.

Another potential future research topic is the continual professional development

(CPD) of practitioners in the subject of SUDS and retrofitting, where experience of

professionals in the field could be compared and contrasted with other approaches

described in the literature. Further potential areas of study could be an investigation

of the advantages and disadvantages of promoting SUDS champions in local

authorities around Ireland.

123

124

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140

APPENDICES

141

Appendix A: Terminology and Key Definitions

The movement towards natural drainage mechanisms has given rise to a variety of

terms used to describe sustainable stormwater management from country to country.

These include terms that are based on similar techniques of stormwater

management from a strategic level to source control that express a philosophy to

move towards a natural method means of drainage. There are three terms utilised

globally; Best Management Practices (BMP) (United States), Water Sensitive Urban

Design (WSUD) (Australia) and Sustainable Urban Drainage Systems (SUDS)

(Europe) in which the research has primarily focused on. The terms are defined

below:

(a) Surface water Management Measures (SWMM)

Surface water management measures (SWMM) encapsulates a variety of control

and treatment strategies designed to mitigate impacts on water quality and flood

control. Practices have developed through the last century in countries such as the

United States, Scandinavia and Japan (Ellis, 1995). SWMM is applied through a

specific measure which encompasses the following practices described below:

(b) Water Sensitive Urban Design (WSUD)

The term Water-Sensitive Urban Design (WSUD) derives from Australia and

represents a holistic method to manage water in urban areas. The technique of

WSUD implies an integrated, adaptive, coordinated and participatory philosophy to

urban water management holistically. In Scandinavia the same approach may be

recognised as Sustainable Stormwater Management (Astebol et al., 2004). The

objective is to maintain or replicate the pre-development water cycle through the use

of design techniques to create a functionally equivalent hydrological landscape.

(c) Best Management Practices (BMP)

Barraclough (2012, p1) identifies the term "Best Management Practice," or BMP, as

a derivative from the Clean Water Act (1972), now commonly used in the language

of environmental management. A Best Management Practice (BMP) as defined by

the U.S. Clean Water Act:

142

“...is a technique, process, activity, or structure used to reduce the pollutant content

of a storm water discharge. BMPs include simple non-structural methods, such as

good housekeeping and preventive maintenance. BMPs may also include structural

modifications, such as the installation of bioretention measures”.

Such approaches influenced UK guidance on urban drainage through the 1990’s

thus beginning the UK’s practice of Sustainable Urban Drainage Systems (SUDS)

(Butler & Davies, 2011). In conclusion Hamill (2011) observes that regardless of the

term the underlying principles are shared.

(d) Sustainable Urban Drainage Systems (SUDS)

Sustainable Urban Drainage Systems (SUDS) are intended to minimise the impacts

of development on the quantity and quality of runoff and maximise amenity and

biodiversity opportunities of the area. The philosophy of this system is to replicate, as

closely as possible, the natural drainage from the lands prior to development,

thereby minimising the impact of the development on water quality in the receiving

waters and quantity of runoff in the area. SUDS drainage should be designed to treat

runoff and return it to the environment as close to the source as possible and in as

many locations as possible, thus spreading the impact on receiving waters.

Sustainable drainage can only be effectively implemented at a site if it is

incorporated in a developer’s plans at the earliest possible stage.

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Appendix B: Vogelwijk, Den Haag: Introduction

The second case study of Vogelwijk is located in the affluent northwest district of

Segbroek in Den Haag. The flat residential area was influenced by the garden town

concept, built between the 1920’s (Hooimeijer et al., 2008).

Figure 1.1: Vogelwijk Site plan According to the most recent population of the municipality of The Hague District

will: Vogelwijk has a population of 5,019 inhabitants. The middle class suburb has a

typical higher average age compared to overall Den Haag, with the average age of

residents at 41.3 (Rietschoten, 2014). It is also reflected on ownership rates with

More than 90% of the homes are owner occupied. According to Hooimeijer (2008), it

fairs better when compared to the surrounding Segbroek urban district as a whole,

when it comes to:

Green infrastructure: High levels of G.I. in and around the district and

many outdoor sports facilities.

Income: a higher income per household.

Employment: an extremely low unemployment figure.

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Contextually the study area has an interesting topography as it is directly connected

to the dunes and the sea. The dune habitat is listed under Natura 2000 for its high

levels of biodiversity.

Driver and delivery

Vogelwijk is a typical suburban neighbourhood in that an ageing infrastructure

combined with increased inflows prompted a combined sewer upgrade. For Den

Haag Municipality and MWH the option of upgrading was installing a separate sewer

separation programme over 8 phases (Ashley et al., 2011).

Phase 2 which centres around the case study at hand is a redevelopment of a

programme which covers 450 properties from 6km combined sewers for a 36 ha total

area that is 50% impervious. New stormwater sewers link four underground shallow

infiltration tanks. In the initial phases only runoff from roads and hard surfaces are

being separated (Ashley et al., 2011). New stormwater sewers connect large

infiltrating underground storage tanks with a shallow depth (circa 1m) and typically

200 to 300m3 per tank draining each area 5 ha. Some 95% of rainfall is infiltrated

with 5% overflowing to watercourses and the coast. Roof drainage is not initially

connected although the new stormwater sewers and the tanks have capacity for this.

Design has used a 10 year time series rainfall and two and five year design storms,

assuming some rainfall will pond on the street without disruption.

There are many cellars in the area and shallow infiltration was designed to avoid

flooding these. Residents and others were reluctant to lose green space in the area ,

so infiltration tanks are located below ground spaces.

Challenges faced

In Phase 1, the tanks were constructed with large horizontal floors and a large

number of intermediate roof support columns. During construction a noticeable

amount of sand was washed in, causing a significant loss of capacity. In phase 2,

greater care was taken and the tanks slanted floors isolate and collect sediment in

one place removal. The Groundwater table comes up to the base of the tanks, so

infiltration is also required from the sides. In the green spaces where the tanks are

located, it was necessary to avoid causing problems to existing areas.

145

Stakeholder engagement

Significant public engagement took place to help residents understand what is going

on in the phased redevelopment programme, for example with ‘evening walks’

(Vogelwijk, Den Haag, 2012). Residents thus far have yet to pay for the work that

has taken place as Den Haag municipality is reluctant to compel this. The residents

are also active via social media which has encouraged community empowerment

with a collaborative, sharing approach, which is reciprocal and mutually beneficial,

while at the same time fostering social inclusion (Gilchrist & Taylor, 2011).

Cost

The total cost of phase 2 finished in 2009 totalled 7m at a unit cost of 23m3 per m2

of separated plan area. In this area residents were charged 140 per annum as part

of the overall sewer tax. Road gullies are cleaned three times per year and foul

sewers every 10 years, and stormwater sewers are expected to be cleaned in 20

years.

Success Factors

The main objective of the Vogelwijk sewer separation project was to upgrade an

ageing combined sewer with a new storm sewer connection to infiltration tanks to

lesson water quality impacts into receiving waters minimised. Combined sewer

network now functions in a better way due to stormwater removal. Public satisfaction

has never been higher due to minimal disruption. Green space has been kept and

maintained to a high standard.

Missed opportunities

In contrast to the case studies of Malmo and Sheffield, where a natural SUDS was

implemented, Vogelwijk implemented several shallow subterranean infiltration tanks.

In this case, any added value from the new stormwater infrastructure is not apparent

as the green areas were already there before the tanks were installed. No added

value from exposed surface water has been provided, although groundwater

replenishment has been delivered. Due mainly to cost concerns, the local authority

has failed to take advantage of the multi-value opportunities. From this it is clear that

Managing surface water so that it can help to deliver multiple functions is a major

opportunity for improving urban environments and also adding value that cannot be

obtained from burying stormwater infrastructure.

146

Appendix C: Combined sewers and combined sewer overflow

From the larger perspective of approaches to surface water drainage, it is

excessively frequent for an urban area to over-rely on piped sewer systems to

convey run-off as rapidly as possible (Stovin et al., 2009, Evans, 2013). The inherent

nature of piped systems like CSS’s (combined sewer systems) tend to increase the

speed and volume of surface run-off, which pose a significant element of flood risk in

many situations (Stovin et al., 2009). Many cities across the globe rely on combined

sewer systems as a means of treating surface water (Swan, 2007).

In Ireland it is unknown the percentage of CSS’s however it is sure to reflect less

than the UK, in that most of the older sewage systems are combined accounting for

70% by total length (Butler, 2011). ‘Combined’ sewers carry both foul and sewer

runoff. Figure 2.1 is indicative of a simplified sewer network and its arrangement,

with a small proportion of a sewer networks complex branching system (Butler,

2011). The figure represents a town located beside a natural water system. The

combined sewer system carrying foul and surface water together in the same pipe,

conveyed to a wastewater treatment plant (WTP) before being discharged into the

water course.

Figure 5.2.1: Combined Sewer (schematic plan) (Butler, 2011, p19)

Combined sewers have two main flow characteristics; during dry weather it will

mainly carry foul, changes occur during precipitation the flow increases due to

addition of surface water. When precipitation occurs, even slightly, surface water

flows will predominate, reaching up to 50 or 100 times the average foul water flow

(Butler, 2011). However Swan (2003), highlights how during heavy and unpredicted

localised rainfall sewers and WTP’s lack capacity in the treatment process. As a

147

solution, during excessive rainfall, the Combined Sewer Overflow (CSO) rapidly

diverts the flows to a receiving water body as shown on figure 2.2 below.

Figure 5.2.2: CSO inflow and outflow (Butler, 2011, p19)

According to Evans (2013) CSO’s are implemented as a safety valve to the sewer

system. As shown on figure 2.2, CSO’s basic function are a relief flow for excess

water flows that would normally cause flooding to pass directly into water courses,

excess flows or ‘spill flows’ are made up of stormwater mixed with wastewater.

These spill flows discharge during, or shortly after, periods of rainfall, when levels of

receiving waters have risen and in an effort to dilute foul sewage into the surface

water. The water retained is referred to as ‘the setting’ and is an important quality of

CSO’s (Butler, 2011). Modern CSO’s are fitted with filters that obstruct solids of more

than 6mm in 2-dimension discharging (Evans, 2013).

Problems associated with conventional sewer systems

The ‘safety valve’ role of the CSO for traditional drainage systems is essential, yet in

conjunction with this is the excessive polluted discharges and sewer flooding issue

with CSO’s (Evans, 2013). In a study by Swan (2003) it is suggested that the main

problems with excessive CSO emissions from overloaded combined sewers systems

are:

Health: Multiple pathogen bodies are present within raw sewage; and

depending on rates of exposure and concentration these may cause illness.

Although sewage overflows are diluted by rain and river water, they may still

represent a slight health hazard (FWR, 1994).

Aesthetic: Another major problem associated with CSO discharges is the

release of unsightly material (e.g. condoms, sanitary towels) into the natural

148

environment. This produces obvious public concern, and complaints to the

responsible water authority.

Environmental: Combined sewer overflows contain a variety of organic,

chemical and industrial wastes. If the concentrations, or spill frequencies, of

CSO discharges are significantly high then the receiving water and its aquatic

life may be harmed. Discharges from separate sewer systems can also pose

pollution problems within receiving watercourses especially in catchments

with a high number of foul water misconnections to the surface water system,

or where high levels of surface pollutants are conveyed into the stormwater

sewer system. It is evident, that in light of these problems, there are obvious

benefits to be gained by eliminating, or limiting, CSO discharges. (p, 6)

Sewer flooding/surcharging problems

Further to problems associated with combined sewers are network flooding and

surcharging of systems that mainly occur when the hydraulic capacity of the system

is exceeded during extreme storm conditions (Swan, 2003). The events from a CSO

in regular intervals are not only a concern for general health, but also can cause

damage to property and general inconvenience. Levels of surface water flooding are

set out and monitored by levels of 'performance' and 'service' parameters.

Engineers utilise the ‘Level of performance criteria’ to define unacceptable

frequencies (in terms of design storms) for flooding or surcharging events from a

given drainage system (See figure 4.3 below)

149

Figure 5.3: Examples of different design standards may be applied for different types of drainage systems (indicative not exhaustive) when retrofitting or for a new development

(Digman et al., 2014, p12)

Stovin (2009) highlights the issue that over the past four decades of scientific

research and practice, urban runoff has largely eluded control by technological

means. As seen above the traditional systems fail to recognise the value of water

and have detrimental impacts on the water system. Reflected in an interview with a

stormwater engineer carried out by Karvonen (2011) when interviewee notes:

“The fundamental problem with conventional stormwater management may be the

mindset. It does not treat water as a valuable resource but more like a problem to

solve, or even worse, seeks to export it as a waste product”. (p15)

150

Appendix D (i): SUDS Designs

Table 5.1: Pollutants SUDS are designed to remove, their effects how they are transported and how they are removed

(Adapted from Wilson et al., 2004)

Pollutants Environmental Effects Transport Mechanisms SUDS Removal Mechanisms

Nutrients Phosphorous, Nitrogen

Algal growth, eutrophication and reduction in clarity, results in fish kills

Dissolved in water or attached to sediment

Sedimentation, biological removal, denitrification, precipitation

Sedimentation Total suspended solids (TTS)

Increased turbidity, lower dissolved oxygen levels, smothering of aquatic habitats

Carried within water Sedimentation, filtration

Pathogens Bacteria, Viruses

Human health risks via Carried within water or attached to sediment

Attach by micro-flora, sunlight, filtration, absorption (although viruses will be infectious until they are killed) Reduced length of survival in warm dry soils Novotny & Olem (1994)

Hydrocarbons Total petroleum hydrocarbons, polycyclic aromatic hydrocarbons, volatile organic compounds (VOC’s)MTBE

Cause of toxicity of water, bio accumulates in aquatic species. Reduces oxygen levels in water

Predominatly attached to sediment (70%) (Mitchell et al.,2001) VOC’s and MTBE’s dissolve in water

Sedimentation, filtration, absorption, biodegradation (time can vary from months to years depending on volatilisation)

Metals Leads, copper, cadmium, mercury, zinc, chromium, aluminium

Cause of toxicity of water, bio accumulates in aquatic species. Can result in killing fish

The majority of metals in run-off are attached to sediment (Pitt et al., 1996) although some are dissolved. Zinc in runoff is predominantly soluble from areas, where as lead is predominatly attached to sediment (Novotny, 1995)

Sedimentation, absorption, filtration

Pesticides Cause of toxicity of water, bio accumulates in aquatic species. Algal growth

Dissolved in water or attached to sediment

Biodegradation, biological process absorption.

Other Chlorides

Cause of toxicity of water Dissolved in water Prevention (Chlorides do not absorb to soils, cannot be dissolved and are difficult to remove (Pitt et al., 1996)

Cyanide Cause of toxicity of water Dissolved in water or attached to sediment

Under acidic conditions in the presence of strong sunlight, sodium ferrocyanide is known to break down, generating toxic cyanide in water will form hydrogen cyanide and evaporate (Mangold, 2000)

Litter Visual impact and threat to wildlife

Deposition in SUDS, directly carried along by water or windblown

Trapping usual outlets guards, remove during routine maintenance

Organic Matter The BOD of organic wastes removes dissolved oxygen in receiving waters. Result is death of aquatic fish

Carried in water Filtration, sedimentation, biodegradation

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Appendix D (ii): SUDS Concepts

Table 2.2: Advantages & disadvantages of various SUDS concepts. (Adapted from Woods-Ballard et al., 2007)

Sustainable Urban Drainage System

Advantages Disadvantages

Swale easy to incorporate into landscaping

good removal of urban pollutants

reduces runoff rates and volumes low capital cost

maintenance can be incorporated into general landscape management

Pollution and blockages are visible & easily dealt with.

Not suitable for steep areas significant

Not suitable in areas with Roadside parking

Limits opportunities to use trees for

Landscaping

Risks of blockages in connecting pipework.

Bioretention Can be planned as landscaping features

Very effective in removing urban pollutants

Can reduce volume and rate of runoff

Flexible layout to fit into landscape

Well-suited for installation in highly impervious areas, provided the

System is well-engineered and

Adequate space is made available

Good retrofit capability.

requires landscaping and

management

susceptible to clogging if surrounding landscape is poorly managed

Not suitable for areas with steep slopes.

Pervious pavements

effective in removing urban runoff pollutants

lined systems can be used where infiltration is not desirable, or where

soil integrity would be compromised

significant reduction in volume and rate of surface runoff

suitable for installation in high density development

good retrofit capability

no additional land take, allows dual use of space low maintenance

removes need for gully pots and manholes

Eliminates surface ponding and surface ice.

Good community acceptability.

Cannot be used where large sediment.

loads may be washed/carried onto the surface in the UK, current practice is to use on highways with low traffic volumes, low axle loads and speeds of less than 30 mph

Risk of long-term clogging and weed growth if poorly maintained.

Detention Basins Can cater for a wide range of rainfall events can be used where groundwater is vulnerable, if lined simple to design and construct.

Potential for dual land use.

Easy to maintain.

Safe and visible capture of accidental spillages.

Little reduction in runoff volume.

Detention depths may be constrained by system inlet and outlet levels.

Infiltration basins Reduces the volume of runoff from a Drainage area.

Can be very effective at pollutant removal via filtering through the soils.

Contributes to groundwater recharge and baseflow augmentation.

Simple and cost-effective to construct.

Changes in performance easy to observe.

potentially high failure rates due to improper sitting, poor design and lack of maintenance, especially if

Appropriate pre-treatment is not incorporated.

Comprehensive geotechnical.

Investigations required to confirm suitability for infiltration.

Not appropriate for draining pollution hotspots where high pollution concentrations are possible.

Requires a large, flat area.

Ponds Can cater for all storms good removal capability of urban pollutants.

Can be used where groundwater is vulnerable, if lined.

Good community acceptability.

High potential ecological, aesthetic and amenity benefits.

May add value to local properties.

No reduction in runoff volume.

Anaerobic conditions can occur without regular inflow.

Land take may limit use in high density sites.

May not be suitable for steep sites, due to requirement for high embankments.

Colonisation by invasive species could increase maintenance.

Perceived health/safety risks may result in fencing/isolation of the pond.

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Stormwater wetlands

Good removal capability of urban pollutant.

If lined, can be used where groundwater is vulnerable good community acceptability.

High potential ecological, aesthetic and amenity benefits.

May add value to local property.

Land take is high.

Requires baseflow.

Limited depth range for flow attenuation.

May release nutrients during non-growing season.

Little reduction in runoff volume.

Not suitable for steep sites.

colonisation by invasive species

Would increase maintenance.

Performance vulnerable to high sediment inflows.

Perceived health and safety risks may result in fencing and isolation of wetland.

Green roofs Mimic predevelopment state of building footprint.

Good removal capability of atmospherically deposited urban pollutants.

Can be applied in high density developments.

Can sometimes be retrofitted.

Ecological, aesthetic and amenity benefits.

No additional land takes.

Improve air quality.

Help retain higher humidity levels in city areas.

Insulates buildings against temperature extremes.

Reduces the expansion and contraction of roof membranes.

Sound absorption.

Cost (compared to conventional runoff.

Not appropriate for steep roofs.

Opportunities for retrofitting may be limited by roof structure (strength, pitch etc).

Maintenance of roof vegetation.

Any damage to waterproof membrane likely to be more critical since water is encouraged to remain on the roof.

Water Butts Easy to construct, install and operate.

Easy to retrofit.

Inexpensive.

Marginal stormwater management benefits.

provides water for non potable water

uses, e.g. garden watering

High risk of blockage of small throttles.

Very limited water quality treatment benefits.

property owner responsible for operation and maintenance, so cannot be guaranteed

Geo-cellular System Modular and flexible.

Dual usage i.e. infiltration and/or storage.

High void ratios (up to 96%) providing high storage volume capacity lightweight, easy to install and robust.

Capable of managing high flow events.

Can be installed beneath trafficked or non-trafficked areas (providing structural performance is proven to be sufficient).

Long-term physical and chemical stability.

Can be installed beneath public open spaces, e.g. play areas.

No water quality treatment.

Sand Filters Flexibility of design.

Efficient in removing a range of urban runoff pollutants.

Suitable for retrofits and in tightly constrained urban locations.

Not recommended for areas with high sediment content in runoff.

Long detention times can support algae growth and lead to filter clogging.

Minimum hydraulic head of 1.2 m required (0.3 m for perimeter filters).

Negative aesthetic appeal/possible odour problems.

Nitrate generation from sand filters has been observed.

Not suitable for large catchment areas.

High capital cost and maintenance burden.

Filter Strips Well-suited to implementation adjacent to large impervious areas.

Encourages evaporation and can promote infiltration.

Easy to construct and low construction cost.

Effective pre-treatment option.

Easily integrated into landscaping and can be designed to provide aesthetic benefits.

Large land requirement.

Not suitable for steep sites.

Not suitable for draining hotspot runoff or for locations where risk of groundwater contamination, unless infiltration is prevented.

No significant attenuation or reduction of extreme event flows.

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Appendix E: Illustrated SUDS concepts

Sustainable Urban Drainage Systems (SUDS) have been defined as a series of

management practices and control devices that are designed to control stormwater

in a more sustainable fashion than achieved by conventional techniques (CIRIA

C522, 2000). The SUDs concepts have been further analysed based on their multi-

functional ability of the SUDS technique involved. This approach is adopted by

Ashley (2011) when stating:

“There are disagreements in the UK as to whether or not piped or so-called

‘sustainable’ drainage systems (SUDS) are best, usually on cost grounds.

However, these are rendered irrelevant if a multi-value approach is taken.

Piped, or underground SUDS, cannot provide the additional benefits that

surface systems can in urban areas. There are now a number of studies that

demonstrate that multi-functional land use, with appropriate utilisation of

surface water management systems, can deliver significant benefits to society

as a whole”. (p3)

Figure 2.4.1: Downpipe Disconnection

(EPA, 2014)

Downspout disconnection

Dublin has recently introduced a small programme to encourage people to

disconnect their (roof drainage) downspouts from piped drainage networks. Often

property owners are given “I have disconnected” plaques, which encourages

neighbours by example, especially in the case of early adopters.

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Figure 3.4.2: Rain garden

(McCarthy, 2014)

Rain Garden

Rain gardens are structural stormwater controls that capture and treat stormwater

runoff from frequent rainfall events. Excess runoff from extreme events is passed

forward to other drainage facilities. The water quality volume is treated using soils

and vegetation in shallow basins or landscaped areas to remove pollutants. The

filtered runoff is then either collected and returned to the conveyance system or, if

site conditions allow, infiltrated into the surrounding soil. Part of the runoff volume will

be removed through evaporation and plant transpiration. Suitable flow routes or

overflows are required to convey water in excess of the design volumes to

appropriate receiving drainage systems safely.

155

Figure 4.4.3: Attenuation pond

(McCarthy, 2014)

Ponds

Ponds can provide both stormwater attenuation and treatment. They are designed to

support emergent and submerged aquatic vegetation along their shoreline. Runoff

from each rain event is detained and treated in the pool. The retention time promotes

pollutant removal through sedimentation and the opportunity for biological uptake

mechanisms to reduce nutrient concentrations.

Figure 5.4.4: Permeable Pavements

(Austin, 2012)

Permeable pavements

156

Pervious pavements provide a path suitable for pedestrian and/or vehicular traffic,

while allowing rainwater to infiltrate through the surface and into the underlying

layers. The water is temporarily stored before infiltration to the ground, reused, or

discharged to a watercourse or other drainage system. Pavements with aggregate

sub-bases can provide good water quality treatment.

Figure 6.4.5: Swales and soakaways

(McCarthy, 2014)

Infiltration, including swales and soakaways

Swales are linear vegetated drainage features in which surface water can be stored

or conveyed. They can be designed to allow infiltration, where appropriate. They

should promote low flow velocities to allow much of the suspended particulate load in

the stormwater runoff to settle out, providing effective pollutant removal. Roadside

swales can replace conventional gullies and drainage pipes.

157

Figure 7.4.6: Detention Basin

(McCarthy, 2014)

Detention basin

Detention basins are surface storage basins or facilities that provide flow control

through attenuation of stormwater runoff. They also facilitate some settling of

particulate pollutants. Detention basins are normally dry and in certain situations the

land may also function as a recreational facility.

Figure 8.4.7: Wetland

(EPA, 2014)

Wetlands

Wetlands provide both stormwater attenuation and treatment. They comprise shallow

ponds and marshy areas, covered almost entirely in aquatic vegetation. Wetlands

detain flows for an extended period to allow sediments to settle, and to remove

contaminants by facilitating adhesion to vegetation and aerobic decomposition. They

also provide significant ecological benefits. (Woods-Ballard, 2007).

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Appendix F: SUDS scorecard assessment

Table 5.3: Score card assessment utilised for adoption of SUDS retrofits

Criteria Description Score

Performance What surface water (flooding and or water quality) benefits are realised based on three types of events?

U= Unacceptable and should be eliminated from further consideration -2= severe negative impact -1= moderate negative impact 0= no impact +1= moderate positive impact +2= significant impact

Technical- Practicability Is it technically possible and buildable? Can be easily maintained?

Technical- Robustness Is it robust and reliable? Can it be modified or damaged by a third part inappropriately

Adaptability Is it flexible enough to adapt with climate change?

Acceptability Will stakeholders accept the measures?

Economic Is the benefit likely to exceed the cost

Affordability Are the measures or options affordable?

Social Will the community benefit or suffer from the measure?

Environmental Will the environment benefit or suffer from the measure?

Key Drivers Will it help the drivers set out?

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Appendix G (i): The European Flood Directive 2007/60/EC

The European Flood Directive 2007/60/EC

The Floods Directive 2007/60/E, published November 2007, is a complementary

document to the Water Framework Directive consequently setting out a framework

for assessment and management of flood risks within the EU (MWH, p8, 2014). As

part of the Floods Directive member states implement three types of flood provisions

in an attempt to restore the ‘natural’ hydrological process within the water cycle as

referred to by Shaw (2011):

“Preliminary flood risk assessments (to be complete in 2011);

Flood hazard and risk maps (to be completed in 2013);

Flood Risk management plans (to be completed in 2015)”. (p428)

Both the Water Framework Directive and Floods Directive are considered a

considerable piece of legislation that aim at restoring the ‘natural’ hydrological

processes in water, an approach advocate in Australia (MWH, 2014). Within the

context of this project, the European Drivers for flood and water management are the

Flood Directive (EC, 2007) and the Water Framework Directive (EC, 2000) which in

accordance with Chapter V, Article 9 of the Flood Directive should be coordinated,

“focusing on opportunities for improving efficiency, information exchange and

for achieving common synergies and benefits having regard to the

environmental objectives laid down in Article 4 of Directive 2000/60/EC”.

Though closely aligned, the Water Framework and Flood Directive are implemented

to member states in two forms. The Water Framework Directive sets out ridged

objectives to classify and improve water quality. Conversely, Adoption of the Flood

Directive transposes flexible approach to European legislation, allowing for different

flood management practices, data and prioritisation of reducing adverse

consequences (Shaw, 429, 2011).

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Appendix G (ii): Adoption of EU Directives in UK Legislation

In the UK there is a framework of policies and mechanisms for the management of

surface waters derived from provisions set out by the Water Framework Directive

and the development of national policies (Butler, 2011, P10, 12). Historic policies

marked by the Water Resource Act of 1963 which can be seen as the beginning of

river basin management. These approaches to stormwater management vary

between England/Wales, Northern Ireland and Scotland yet the regions apply

roughly equivalent policies, activities and management framework in all cases

(Shaw, 2011, P428) Part of the impetus in shifting perspectives on stormwater

management arose from the floods of 2007.This shift saw Pitt review mechanisms of

flood risk management and produced 92 recommendations (Pitt, 2008, p82). It

essentially transposed the Flood and Water Management Act 2010 into legislation

(MWH, 2014, 94).

The Flood and Water Management Act (2010) introduced an integrated approach

regarding water and flood risk management. Changes will occur through the

establishment of the SUDS Approving Body (SAB) which is the body unitary/local

council authorities) that approves standards for design, construction and

management of stormwater (DEFRA, 2011). Therefore, SAB’s will replace the

developers and adopt the approved SUDS scheme with a view of taking ownership

and maintenance responsibilities. Hamill (2011) comments, that new developments

no longer have the right to connect to existing surface water sewers (Foul sewers

unaffected). However where approved SUD system is integrated into a design are

any residual flow may still be discharged to a public sewer (Hamill, 2011, p552).

These standards were published in draft form in the “National Standards for

Sustainable Drainage Systems – Designing, constructing, operating and maintaining

drainage for surface runoff” (O’Connor, 2011).There is now an impetus on to

National Standards of SUDS in England and Wales throughout developing new

building, roads and highways (Hamill, 2011). The main objective is that SUDS can

be applied in a hierarchical process and to be considered at all stages of the

planning sphere from regional to local levels, as advocated by the SUDS treatment

train. The cumulative effect of the adopted approach is that SUDS will be recognised

as the norm and traditional drainage systems will become the exceptions in new

developments (O’Connor, 2013).

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In Scotland, the Environmental Act 1995 saw the introduction of a regulatory body in

the Scottish Environmental Agency (SEPA). Similar to England in that the major

flooding event of 2002 changed the perspective on conventional urban drainage

systems, coinciding with the introduction of the Water Framework Directive (MWH,

2014). This lead a succession of legislation in the WEWS Act in 2003, Flood Risk

Management (Scotland) Act 2009 and the Water Environment (Controlled Activities)

(Scotland) Regulations (CAR) 2011, which came into force in March 2011.

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Appendix H (i): Historical development of drainage engineering Ireland

The literature reviewed in this section examines the growth of Ireland’s drainage

systems with particular emphasis on Dublin city.

Background

Irelands growth of infrastructure, development and subsequent impervious surfaces

can be is attributed to the Irish ‘Celtic Tiger’ (Ireland’s economic boom). Creating a

platform for this growth was the National Spatial Strategy for Ireland from 2002 to

2020 (National Spatial Strategy, 2002). This focused on developing towns and cities

for commercial, residential and industrial uses. Rapid growth in development through

the 1990’s resulted in pressure on infrastructure and the mass creation of impervious

surfaces. Many of these ‘renewable’ areas that have been identified for further

development are located along the corridors of the Irish river network and will

increase the pressures on these watercourses to cater for additional stormwater

runoff. Consequently, encouraging the use of sustainable approaches to stormwater

management and having accurate methods for estimating flows and volumes for

these systems is increasingly important (O’Sullivan et al., 2008).

Sustainable stormwater should be of utmost importance in Ireland as the majority of

drinking water (81.9%) originates from surface water (i.e. rivers and lakes) with the

remainder originating from groundwater (10.3%) and springs (7.8%) (EA, 2008).

Unfortunately there have only been tentative steps away from traditional solutions by

local authorities and developers since the publication of the Greater Dublin Drainage

Study (GDSDS) (DDC, 2005). According to Doyle (2003)

“This is of particular concern in Dublin, where many of the densely built up

areas are at the downstream end of rivers and drainage systems and there is

increased pressure to allow upstream developments”. (p77)

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Drivers for change

Public interest in the quality of our surface water has never been higher; however

there are significant problems to be addressed in future.

Climate Change:

Climate change is no longer viewed by mainstream scientists as a future threat to

our planet and our species. It is a palpable phenomenon that already affects the

world, they insist. Predications for Ireland indicate that it will be subjected to much

more unpredictable/volatile weather patterns in the future. An EPA report identifies

that changing patterns of precipitation will impact on water services provision and on

levels of pollution and contamination, with significantly wetter winters particularly in

the west, and drier summers particularly in the south east and storm occurrences of

a greater intensity. Other impacts include damage to water infrastructure due to cold

snaps or water shortages in summer leading to greater pressures on water sources.

Increases in population:

The CSO estimates that Ireland’s population could rise (under the highest growth

scenario) by nearly 1.5 million between 2006 and 2021 – an average annual rate of

population increase of almost 2%, equivalent to that observed during the inter-

censual period 2002-2006. Projecting that high growth rate forward to 2041, the

population could increase by a further 1.4 million between 2021 and 2041.

Population growth of this scale will significantly increase the demand for water and

waste water services. It is also reasonable to expect that when the economy enters a

sustained period of recovery that most of this growth will be seen in urban areas

leading to demand for housing and new business development. This will place

further pressure on water/sewerage systems in built up areas, some of which are

already under significant pressure.

The Water Framework Directive (WFD):

The WFD requires a catchment or river-basin approach for the management of water

and obliges all Member States to protect and improve their waters with a view to

achieving good ecological status by 2015 or, subject to specific conditions, over two

subsequent planning cycles out to 2021 or 2027.

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Appendix I (i): SUDS Guidance in Ireland

Table 5.4: Key Guidance documents for urban hydrology

(Adapted from Shaw et al., 2011)

The SUDS manual (CIRIA report C697), 2007

Guidance for the planning, design, construction, operation and maintenance of SUDS. Includes landscaping, biodiversity, public perception and community integration, water quality treatment and sustainable flood risk management

Designing for exceedance in urban drainage: good practice (CIRIA report C635), 2006

Advice for design and management of urban sewerage and drainage systems to reduce the impacts that arise when flows occur that exceed this capacity. Includes both underground systems and overland flood conveyance. Advice on risk assessment procedures and planning for extreme events.

Code of Practice for the Hydraulic Modelling of Sewers, 3rd ed (WaPUG; the Wastewater Planning Users Group, part of the Chartered Institute of Water and Environmental, 2002

Covers all aspects of model building for hydraulic analysis and testing, flow surveys and verification, and documentation.

Retrofitting to Manage Surface Water (CIRIA report C713), 2012

Guidance that integrates the principles of urban design with surface water management.

Greater Dublin Strategic Drainage Study GDSDS (Dublin Drainage Consultancy), 2005

A strategic study with the aim to identify policies, strategies and projects for the development of a sustainable drainage system for the Greater Dublin Region.

165

Appendix J: Developing a Cost Benefit Analysis (CBA)

Different valuation methods have been used for financial assessment of SUDS

retrofits. Cited by Booth (2014) and Jianbing (2010) they evaluate that Cost-Benefit

Analysis (CBA) as a justification to the public, local authorities or governments in

whether benefits of a scheme outweigh the costs of implementation and hence

whether there is a substantial need to invest in the strategy proposed. In an attempt

to assessing the benefits and costs of a scheme, CIRIA (2012) list two main

elements; the tangible and the intangible. The tangible is a straight forward method

of defining costs through monetary terms, i.e. capital outlay. Alternately, intangible

benefits such as attractiveness/visual amenity can be difficult to calculate (Gordon-

Walker et al., 2007). The concept of associating financial values with intangible

benefits is emerging such as ecosystems services and green infrastructure.

However, evaluating intangible benefits can be challenging as many of these are

subjective. CIRIA (2012).

Figure 5.5: Cost-Benefit analysis of SUDS scheme- model assumptions

166

Appendix K: Opportunities for SUDS retrofit

Table 5.5: The main type of SUDS retrofits, techniques and the most common

opportunities for retrofitting

(Adopted from Ashley et al., 2011, p230)

167

Table 5.6: Description and implementation opportunity for SUDS retrofit (Adopted from EA, 2007, p7) Technique Description Implementation

scenario Coverage potential for retrofit

Permeable paving

Instead of using impervious bituminous or concrete (conventional surfaces), permeable paving blocks are used.

When conventional surfaces require resurfacing, approximately every 20- 40 years, it is possible to replace with permeable surfaces. Benefits will come from reduced drainage charges and from reduced CAPEX and OPEX costs.

It is estimated that it is possible to retrofit around 50 per cent of OFF ROAD hard standing surfaces with porous paving. This is a conservative judgement based on an expert view. Further research might indicate that this percentage could be increased.

Rainwater harvesting

Disconnection of premises from the drainage system to provide an “in-house” collection and storage system for rainwater that can be used for non-potable water use.

Large premises could disconnect from drainage infrastructure and install a rainwater harvesting system. This would most likely be done during building refurbishment programmes. Benefits would arise in reduced drainage charges and water bills.

Around 75 per cent of industrial and commercial premises could adopt rainwater harvesting systems, and 50 per cent of public buildings, such as schools and hospitals, could do the same.

Water butts Water butts store rainwater from roof drainage and are particularly applicable for household properties with gardens. Their attenuation benefits are limited when they are full.

This is a relatively easy and cheap option for all households (not individual apartments). Water butts are however likely to be full when attenuation for flooding is required and some further storage needed. Benefits for households will be reflected in lower water bills.

There is the potential for 90 per cent of semidetached and detached properties to install water butts, and for around 45 per cent of terraced housing.

Swales, infiltration ditches, filter drains

These drainage systems provide good attenuation for surface water run-off, particularly from highways.

Generally these SUDS techniques have greater benefits for new roads and hard surfaces – greenfield or brownfield – but can also be introduced during road upgrading projects. Benefits are most likely to be realised in their local context.

These SUDS techniques are more limited in a retrofit context, particularly in an urban situation. Roads in rural areas have a greater potential for retrofitting, around 20 per cent, whilst in urban areas this might be as low as four per cent.

168

Appendix L: Overview of projects in Malmö

Table5.7: Overview of the described sustainable urban drainage projects in Malmö

(adopted from Starhe,2008, p20)

Name Year of implementation Type of SUDS concept

Toftanäs Wetland Park 1989–1990 Wetland, controlled flooding

Sallerupsvägen 1992 Pond, meandering creek, root zone

Kasernparken 1992–1993 Pond, reedbed

Amiralsgatan 1995–1996 Ponds

Husie Lake 1996–1997 Detention lake

Olof Hågensens wetland 1997 Wetland, controlled flooding

Vanåsgatan 1999 Swales, inverted traffic bumps

Svågertorp 1998–2001 Soakaways, ponds

Limhamnsfältet 1998 Swale

Augustenborg 1998–2005 Green roofs, canals, swales, ponds, permeable pavings, controlled flooding

Bo 01 housing exhibition 2000–2002 Open canals, rain gardens, water artwork

Fjärilsparken 2000–2004 Eco-corridor (regional swale)

Elinelund recreation area 2001–2002 Ponds, filter walls

Gottorpsvägen 2001 Ponds, filter wall

Vintrie 2002–2003 Series of detention ponds

Annestad 2005 Detention canal, controlled flooding

Växthusparken 2005 Eco-corridor (open watercourse and pond)

Tygelsjö eco-corridor 2004–2007 Eco-corridor (wetland, water course and ponds)

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Appendix M (i): Summary of Historical flooding fix map

Figure 5.6: Locations of historical flooding in the West Pier Catchment

1. Glasthule village & Newtownsmith

On several occasions, in recent history, there has been severe road and property

flooding in Glasthule and along the Seafront of Newtownsmith.

In practice it has been found that the levels of the road at the Link Road junction do

not allow for all water to easily pass down Link Road and instead floodwater has,

during recent rainfall events, accumulated in the centre of the village. In addition,

connections to the West Pier sewer line have proven not to be watertight as

infiltration, in addition to flooding at manholes 1926 and 2913, has occurred resulting

in sewerage rising through the road bases, applying large pressures to the road

surface and in some areas bursting through the black-top and flowing out on the

surface. As a consequence many properties and commercial premises have been

flooded. Property 69 in the centre of the village reported that, during the August 16th

170

event in 2008, the floor of the shop lifted due to the pressures and that sewage

seeped up through the floor.

During both events, water was witnessed to be bursting out of manholes 1926 and

2913 to a height of approximately 0.5m above the ground level. A similar height of

water was witnessed during the August 16th event in 2008. This indicates that during

large rain events the head in the West Pier Line in the centre of Glasthule village in

the order of 0.5m above ground level, resulting in a hydraulic grade line in this area

of approximately 6.4mOD.

2. Railway Line at Glenageary and Dalkey Station

Flooding of the railway line resulting in service interruptions has occurred on a

number of occasions. Irish Rail provided a list of flooding incidents on the DART line

for 2007-2009. This indicated that the line was closed completely 3 times between

2007 and 2008 and disrupted for between 4 and 5.5 hours 3 more times between

2008-2009.

It is understood that recent investigation by DLRCC have indentified that a restriction

in size of the entrance to the culvert passing beneath the tracks at Dalkey Station is

likely to have contributed to the flooding at this location. Works have since been

undertaken to enlarge the culvert opening and performance during high flows has

been monitored.

3. St. Catherine’s Road

Figure: indicates road flooding in 2008 on St. Catherine’s Road, a residential road

running adjacent to the DART line between Castle Park and Albert Road DART

crossings. On this occasion floodwaters accumulated after heavy rainfall at this low

point in the road behind the DART boundary wall.

4. Hyde Park Dalkey

Flooding has been reported at Hyde Park on occasions and has been included flows

escaping from a trunk sewer, flowing over the playing pitches and flooding Cuala

GAA clubhouse. Sewer diversion works, which included the provision of some offline

storage, have recently been completed at this location. Flooding of the football

pitches occurred in 2011 storm event, however no property reported flooding.

171

5. Dalkey Avenue & Cunningham Road Junction

Flooding has been reported on numerous occasions from the sewer manhole at the

junction of Dalkey Ave & Cunningham Road.

6. Ardbrugh Road

Flooding of residential properties has been reported in the past on Ardbrugh Road as

a result of high runoff from the quarried part of Dalkey hill. Some flood alleviation

works have been undertaken in this area.

7. Dalkey Roundabout

The flooding of 3 commercial premises occurred in Dalkey during the floods of 2011.

Heavy overland flows from Dalkey Avenue contributed to the ponding of water at this

location.

Appendix M (ii): Background flooding in Glasthule

Background flooding in Glasthule village

The premises of Glasthule Village, over the past 6 years, experienced quite severe

flooding. Over the summers of 2008-2009, two major rainfall events in particular

have caused considerable flooding in Glasthule Village, details of which are

summarised in Table 5.8 below. The recorded intensity of these rainfall events was

highly variable over a small geographical area and, as a consequence, these types

of events, which typically result in pluvial flooding, are impossible to accurately

forecast satisfactorily in advance.

Table 5.8: Summary of rainfall events that have caused severe flooding in Glasthule village

Date Total Rainfall recorded at Church Road (mm)

Total Rainfall recorded at Sandy cove (mm)

Peak Period Peak Intensity (2 minute period) during storm (mm/hr)

16 August 2008

45.4 39.2 10mm in 26 minutes

30

02 July 2009 No data 42.8 22.6mm in 60 minutes

No data

172

The recently installed Emergency overflow from West Pier Trunk Sewer near the site

of Dun Laoghaire Baths at Newtownsmith is constructed for the purpose of

alleviating flooding in Glasthule and recent extreme storms events indicated that the

new overflow has considerably reduced flooding risk at Glasthule village .

However, the relatively minor flooding of approximately 4 commercial properties

during storm events in 2011 is considered to have occurred as a result of catchment

overland surface overflow accumulating in Glasthule village and on the Seafront at

Newtownsmith (i.e. area of the former Glasthule Stream) as a consequence of being

unable to enter the combined sewer piped system further upstream.

Table 5.9: Summarised areas of known historical flooding in the study area and

indicates where in some cases measures have been undertaken to mitigate against

further flooding (see appendix 10 for further detail).

Table 5.9: Summary of study areas historic flooding

no Area of Flooding Status

1 Glasthule village Works undertaken to reduce risk of flooding. New emergency overflow completed in September 2011. Recent overland flooding at this location is under investigation.

2 Railway line Works undertaken to reduce risk of flooding in Dalkey Train Station. Seasonal Springs remain on line between Dalkey & Glenageary.

3 Hyde Park, Dalkey Works undertaken to reduce risk of flooding. On-line storage tanks and sewer diversion pipe construction completed in 2011.

4 St. Catherine’s Road Road flooding remains a risk

5 Dalkey Avenue & Cunningham Road Junction

Works undertaken to reduce risk of flooding.

6 Ardburagh Road Road flooding remains a risk.

7 Dalkey Roundabout Recent flooding at this location is under investigation.

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Figure 5.7: Pattern of previous flooding in Glasthule village

This sewer was designed to operate as a pressure sewer under storm conditions

between Glasthule village and the West Pier Pumping Station. Under extreme flow

conditions, a central manhole in Glasthule was designed to act as an intermittently

pressurised sewer with the intention to become a ‘release point’, which will flood in

order to prevent the flooding of premises in Glasthule village. It was designed to spill

out of a central manhole and in a northerly direction flows over land and out to sea

via a 450mm surface water outfall pipe. Effectively, the central manhole in Glasthule

village was designed to act as a combined sewer emergency overflow. However, in

practice it has been established that road levels do not allow water to easily pass

away from the village; instead, floodwater has, in periods of heavy rainfall, gathered

at the centre of the village (RPS, 2009).

174

Environmental performance in Glasthule village

In total there are 4 principal locations in the network where combined sewer

overflows occur; Bulloch Pumping Station (long sea and short outfalls) and the

recently constructed emergency overflows at Newtownsmith. These overflows, which

are all unscreened, are of the emergency surcharge types which activate in the

event of equipment failure at pumping stations or where incoming flows to pumping

stations exceed pumping capacity. The water receiving discharges from the West

Pier East and Bulloch catchments can be categorised as bathing waters and

therefore classified as high amenity category. Therefore the criteria under the

GDSDS and EU legislation, allow for not more than two spills per bathing season,

which extends from May-August, this includes all overflows. A screening standard of

6mm for all overflowed in any two dimensions is adopted if the spill frequency is

more than 1 spill per year. If the spill frequency is less than 1 spill per year then a

screening standard of 10mm is applied.

Currently overflows from the West Pier system to the Bulloch system occur during

periods of high flows at Glasthule village and excessive flows are discharged by

gravity to sea at Bulloch Harbour Pumping Station long sea outfall. A hydraulic

modelling analysis highlights the existing unsatisfactory intermittent discharge rates

in the catchment area:

Table 5.10: Existing catchment environmental performance- average annual based

on time series

West Pier Long- Sea

West Pier Short-Sea

Bulloch Pump Station

Newtownsmith Overflow

No. Of Spills 14 5.0 9.7 5.0

No. Spills in bathing season

2.7 1.3 2.7 1.3

Total spill volume

239,525 23,516 85,272 15,870

Average spill volume

17,053 4,687 8,888 3,174

The Dun Laoghaire area with its long sinuous coastline, existence of ageing

sewerage systems and multitude of CSOs, provide the ideal environment in which to

investigate the suitability and effectiveness of SUDS retrofitting, in the context of

providing improvements to bathing water quality.

175

Appendix M: Scorecards carried out U= Unacceptable

-2= severe negative

-1= moderate negative

0= no impact

+1= moderate impact

+2= significant impact

Select Measures +12

Table5.11: Scorecard for retrofitting West Pier catchment, Dun Laoghaire

Area Criteria SUDS

Swale Bio Retent

P-pave.

Det-Basin

Inf-Basin

Pond Wet land

G-roof

W- Butt

Geo cell

Sand Filters

Filter Strips

Sally. Rd

Performance

Technical- P

Technical- R

Adaptability

Acceptability

Economic

Affordability

Social

Environment

Key Drivers

Score 13 14 15 12 10 3 10 U U 7 11 11

Area Criteria SUDS

Swale Bio Retent

P-pave.

Det-Basin

Inf-Basin

Pond Wet land

G-roof

W- Butt

Geo cell

Sand Filters

Filter Strips

New town smith

Performance

Technical- P

Technical- R

Adaptability

Acceptability

Economic

Affordability

Social

Environment

Key Drivers

Score 13 13 5 11 8 2 18 U U 7 11 10

Area Criteria SUDS

Swale Bio Retent

P-pave.

Det-Basin

Inf-Basin

Pond Wet land

G-roof

W- Butt

Geo cell

Sand Filters

Filter Strips

Eden Park

Performance

Technical- P

Technical- R

Adaptability

Acceptability

Economic

Affordability

Social

Environment

Key Drivers

Score 13 14 15 11 10 2 10 U U 7 11 11

176

Area Criteria SUDS

Swale Bio Retent

P-pave.

A -Basin

I-Basin

Pond Wet land

G-roof

W- Butt

Geo cell

Sand Filters

Filter Strips

St. Cath. Rd

Performance

Technical- P

Technical- R

Adaptability

Acceptability

Economic

Affordability

Social

Environment

Key Drivers

Score -5 16 15 U U U U 10 15 0 13 13

Area Criteria SUDS

Swale Bio Retent

P-pave.

A -Basin

I-Basin

Pond Wet land

G-roof

W- Butt

Geo cell

Sand Filters

Filter Strips

Residnt.Areas

Performance

Technical- P

Technical- R

Adaptability

Acceptability

Economic

Affordability

Social

Environment

Key Drivers

Score 9 15 14 U U 6 U 15 15 0 13 13

Area Criteria SUDS

Swale Bio Retent

P-pave.

Det-Basin

Inf-Basin

Pond Wet land

G-roof

W- Butt

Geo cell

Sand Filters

Filter Strips

Hyde park

Performance

Technical- P

Technical- R

Adaptability

Acceptability

Economic

Affordability

Social

Environment

Key Drivers

Score 13 11 15 16 10 3 9 U U 10 11 11

177

Appendix N (i) Emails to Personal Interviews

To the following practitioners:

- John Collins- ExecutiveEngineer at Dublin City Council

- Fiona Craven- planning and development engineer at Dublin City Council

- Marianne Beckmann- Strategist Urban drainage VA SYD

- Louise Lundberg- Gronare Stad AB

- Ewald Oude Luttikhuis- Senior Executive Drainage Engineer at The Hague

Municipality Council

- Kees Hufen- Senior Project Manager at MWH

Dear .......,

As a master’s student, from Ireland, attending the University of Gloucestershire

(UK), I am contacting you regarding my Masters dissertation titled "Retrofitting

Sustainable Urban Drainage Systems (SUDS) in Suburban Dublin" as you are a

recognised expert in Urban Water. From my work as an urban planner in the

Architect's Department of Dun Laoghaire Rathdown County Council, where I was

responsible for Green Infrastructure in County Dublin, I have chosen this topic as my

hypothesis.

As part of my dissertation research, I will be applying lessons learnt from case study

Urban Drainage to Dublin in terms of stormwater management as a case study

methodology. I feel your experience in urban drainage in case study would

enormously benefit the research.

There are about six questions which I would like you to consider which would

probably take roughly 30 minutes of your time.

I appreciate your consideration of my request and thank you for your time and I look

forward to hearing from you.

Yours sincerely,

Fergus McCarthy, B.A. PGrad. Dip. (Landscape Architecture),

University of Gloucestershire.

00 353 86 7804706. (Ireland)

178

Appendix N (ii) Personal Interviews

John Collins Senior Executive Engineer at Dublin City Council

Date: 17/04/14

1) Since the introduction of the Greater Dublin Strategic Drainage Study

(GDSDS) how influential do you feel it has been in implementing SUDS

integration in Dublin?

The big benefit of the GDSDS on SUDS is that it has increased awareness

significantly. Some years ago very few people were concerned or knew about SUDS

whereas now it is common knowledge.

2) What changes do you feel need to be implemented, so local authorities/Irish

Water can do to meet the obligations of the EU Water Framework Directive?

Changes that could help meet WFD targets could include more ground or field staff

in local authorities, more implementation of existing legislation, and greater liaison

between stakeholders.

3) What are the major drivers for SUDS in Dublin and strategies have been

adopted to assist in the implementation of widespread SUDS in Dublin?

I think the major driver in Dublin is flood prevention. Dublin City have installed some

integrated constructed wetlands and out of these we get the benefit of flood

alleviation, pollution control and environmental improvement. There is also an

educational benefit as local schools bring students on field trips to the wetlands.

4) In your experience do developers/local authorities tend to focus on large scale

Sustainable Urban Drainage Systems (SUDS) (Retention/Detention Ponds)

as opposed to Source Control Management (Rain gardens/Green Roofs)?

Several years ago the emphasis was on detention ponds / flow rates etc but it has

now moved to looking at quality issues rather than a blunt discharge rate of x l/s

regardless of quality. So for example there is the installation of swales, flower boxes

collecting rainwater.

179

Fiona Craven planning and development engineer at Dublin City Council

Date: 1/4/2014

1) What are the current Drivers behind stormwater management in Dublin at the

moment?

Dublin is seeing a lot of flood risk management from tidal events to fluvial flooding.

Currently one of the biggest issues in Dublin is the problem that built development

over the last 20 years has increase pluvial flooding and increased flow in combined

sewers. This is a problem is caused by a lack of drainage upgrades in combined

sewers and over the last 5 years there has been flooding problems about 3 or 4

times a year. Combined sewers have very low capacity and there has been

significant amount of untreated wastewater flowing into water bodies. Another issue

is the chronic flooding of the roads in Dublin which is very expensive to maintain.

Chronic flooding causes new roads surfaces to be replaces every 4 years.

2) What are the current opportunities or most popular solutions being addressed

to handle the flood risk in Dublin at the moment?

In terms of surface water the Flood Defence Unit of Dublin City council target areas

of high risk flooding and will implement systems manage surface water mainly

through hard solutions.

3) Since the publication of the Greater Dublin Strategic Drainage Study

(GDSDS) has the implementation of SUDS risen?

Firstly, the GDSDS has tightened up the 1998 stormwater policy and nothing much

else has changed. There was great information with the GDSDS; however there was

never training or CPD as part of the Policy. Engagement on SUDS was never

provided appropriately on developments, and currently we are still not seeing full

compliance on SUDS being met by developers. Initially it was difficult to get

developers to comply. Developers gave reasons why SUDS were unfeasible and

these were often accepted unchallenged. Very few sustainable drainage methods

were incorporated into new development. In general, underground tanks and hydro-

breaks were installed.

4) SUDS has become ‘business as usual’ within many European cites, how far is

Dublin off meeting these standards?

Currently Dublin City Council drainage framework is currently formed where

stormwater drainage, waster drainage and the flood risk unit work in isolation. As

Irish Water is currently amalgamating with the Drainage Department this could see a

more joined up focus on drainage problems where more departments are involved

with drainage. It’s hard to foresee at this moment in time how far Dublin is off

meeting these standards.

180

Appendix N (iii) Personal Interviews- Malmo

Marianne Beckmann Strategist Urban drainage VA SYD

Date: 15/04/2014

1) What type of current SUDS measure implemented in Malmo at the moment?

Currently in Malmo, drainage has focused on mainly implementing SUDS as part of

new development. As the city expands, SUDS have been focused mainly in

greenfield agricultural land on the outskirts of Malmo. Augustenborg is the only

retrofit project of its kind and Malmo’s retrofitting focused on small scale stormwater

detention on streets.

2) Since sustainable stormwater management has been introduced to Malmo,

what was the biggest change that took place in Malmo?

We have seen a lot of progress in the intergovernmental department working

together on SUDS.

3) What changes have occurred in since the introduction of the EU Water

Framework Directive?

When it comes to the ‘ecological good status’ of waters in Malmo are not in a good

status meeting the good status of the Directives objectives. Never mind we have

WFD at the back of our minds. Malmo has seen SUDS as a detention measure as

appose to cleansing. Malmo still has a lot of CSO and as more restriction is being

implemented by the Environmental Agency in Malmo on how much water is realised

by CSO’s we will need to use SUDS more to cleanse source point water. We still

haven’t come to any conclusions on how or where we will implement changes to

Malmo’s drainage.

4) What are the drivers behind stormwater drainage in Malmo?

CSO management is a driver. We are potentially planning an upgrading to a

stormwater pipe that connects stormwater sewer systems to the wastewater

treatment plant. Even with lots of SUDS and soft solution’s we can need to use ‘hard’

solution in managing stormwater. SUDS will also be important to manage annual

rainfall and will need to increase these measures as climate change increase rainfall.

181

Louise Lundberg Gronare Stad AB- Worked closely with the retrofit SUDS project

in Augustenborg

Date: 13/04/2014

1) What were the specific drivers behind SUDS in Augustenborg?

Rehabilitation to urban drainage in Augustenborg was driven by constant pluvial

flooding resulting in basements becoming flooded and general combined sewer

problems.

2) What was the outcome of the retrofit project?

Augustenborg has seen has exceeded the amount of benefits initially estimated. It

has seen an increase in biodiversity, amenity spaces, and a number of social

benefits that includes entrepreneurship schemes. Augustenborg no long suffers with

any flooding issue. An example of this in 2007, Sweden experienced a 50 year

rainfall, resulted in the isolation of Malmö from rest of Sweden. However, the SUDS

features in Augustenborg dealt with the extreme precipitation successfully.

3) What best practice concepts might other retrofitting projects draw from

Augustenborg?

Community engagement has been beneficially to Augustenborg. The Initial design

problems were solved by redesigning, re-considering design features and in some

cases removing certain elements of the system, utilising technological solutions, and

extensive consultation with local residents. This continues today with a lot of new

ideas for dealing with rainwater in a more efficient way coming from some residents.

3) Were you satisfied with the outcomes of the project?

Augustenborg is a fantastic example of a retrofit project. However, I feel Malmo’s

approach could have extended into further areas. I don’t see why we there are

verges and sidewalks without SUDS that can reduce against flooding and drainage

problems. Why not take these useless spaces and give them function?

182

Appendix N (iv) Personal Interviews- Den Haag

Kees Hufen Senior Executive Drainage Engineer at The Hague Municipality

Council

Date: 23/04/2014

1) What are the specific drivers of stormwater management in Den Haag?

Driver is the new national legislation that encourages local authorities to collect

stormwater separate from the mixed sewer system. Stormwater getting its own

collecting system. This in order to save energy and to improve efficiency of the water

treatment plants. These measures also reduce the emission/pollution out of the

mixed sewer systems. In Den Haag we implement new storm water systems only

when we can realise them in a cost effective manner. This means that we always

combine several public works in order to save costs.

2) What changes have occurred in since the introduction of the EU Water

Framework Directive?

No changes have occurred regarding sewer management. The part/influence of

sewer system pollution into total water pollution is very small and local compared to

other sources such as agriculture and traffic. Implementing measures in sewers in

order to achieve EU Directive goals is not cost effective.

3) What are the challenges in managing the retrofitted SUD system in

Vogelwijk?

The biggest challenge at the moment is to explain the inhabitants of the Vogelwijk

that the present nuisance due to high ground water tables and wet cellars are not

related to the infiltration systems. Present high water tables are due to last year’s

high rainfall in the dune system behind the Vogelwijk

4) On reflection what do you feel could have been done differently?

I feel the infiltration is not a must and collecting the clean rainwater into the Haag se

Beek - surface water is as sustainable as infiltration into the soil. The infiltration

structures are an additional burden on operation and maintenance.

183

Ewald Oude Luttikhuis Senior Project Manager at MWH- Project Leader on

Vogelwijk SUDS design

Date: 25/04/2014

1) What were the specific drivers in the advancement of storm water and

challenges of integrating the SUDS an existing urban development?

In order to reduce the CSO, flooding and maintain groundwater at a good level. The

design of a SUD couldn’t infiltrate too quickly as not to prevent an increase of

groundwater tables. There are some not water proof cellars in the area. Enough

distance to existing buildings. Keeping the green area’s unchanged. The overflow

pipe had to cross an important road nearby the hospital.

2) How did the Vogelwijk project overcome the institutional barriers between the

different stakeholders involved in the planning and implementation of SUDS

facilities?

There was a meeting with residents. The overflow to the surface water was restricted

to 10% of yearly rainfall by the Water Board because of water quality. This means

there has to be enough storage capacity.

3) What best practice concepts might other retrofitting projects draw from

Vogelwijk?

Bottom can get silted, so there is no infiltration to the ground water anymore. The

construction of the infiltration wall. Cleaning the facility. Therefore the bottom is

made of closed concrete. If you don’t see anything of it, the residents are satisfied.

Don’t cut down trees. Think about top load

4) In your experience did you feel there was a missed opportunity in focusing on

underground SUDS as appose to soft (ground level) SUDS?

In this area I think we did well. If there is more room between the houses other

cheaper and above ground SUDS are possible. These are better for keeping the

water clean. Residents better understand the water system.

5) Were you satisfied with the outcomes of the project?

Yes, although there could be more private pavements and roofs disconnected from

the combined sewer onto the new storm water sewer.

6) On reflection what do you feel could have been done differently with the

project?

Involve the residents to get disconnect their roof from the combined sewer. They

have to do those themselves (or pay for it). The Municipality didn’t want to promote

this, because of the dignified neighbourhood. Our experience is that if the

Municipality.