Jovian Design - Permeable Surface Stormwater Management Feasibility Study

PERMEABLE SURFACE STORMWATER MANAGEMENT
FEASIBILITY STUDY
FINAL REPORT APRIL 2010
City of London
Engineering Review Division
Environmental & Engineering Services
Disclaimer: This report is an academic exercise conducted by graduate students from the University of Western
Ontario. Jovian Design is a fictional entity and has been created only for the purposes of this exercise.
WONDERLAND POWER CENTRE, LONDON, ONTARIO, CANADA

DANIEL BITTMAN | ANIRUDDHA DHAMORIKAR | STEVEN DIXON | JENNA SIMPSON | SYED ZAIDI

April 23, 2010
Lois Burgess, P.Eng.
Division Manager
City of London
Ismail Abushehada, Ph.D., P. Eng.
Development Services Engineer
City of London
RE: Final Report: Permeable Surface Stormwater Management Feasibility Study: Wonderland Power Centre, London,
Ontario, Canada
Dear Ms. Burgess and Mr. Abushehada,
The following document is the Final Report of the Permeable Surfaces Stormwater Management Feasibility Study that has been
requested by the Engineering Review Division of the Environmental and Engineering Services Department of the City of London.
It has been a pleasure to work with both of you and we would like to extend our thanks for your continued support throughout this
project.
Sincerely,
Jenna Simpson, Project Manager
Jovian Design
1151 Richmond Street,
London, Ontario, Canada
N6A 3K7

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Table of Contents
Table of Contents............................................................................................................................................................................ i
Table of Tables .............................................................................................................................................................................vii
Table of Figures ...........................................................................................................................................................................viii
Glossary of Terms..........................................................................................................................................................................ix
List of Abbreviations......................................................................................................................................................................xii
Executive Summary .....................................................................................................................................................................xiii
1. Introduction ................................................................................................................................................................................ 1
1.1 General................................................................................................................................................................................. 1
1.2 Urbanization in the City of London ........................................................................................................................................ 2
2. City of London Development Objectives..................................................................................................................................... 4
2.1 Introduction........................................................................................................................................................................... 4
2.2 Official Plan for the City of London........................................................................................................................................ 4
2.3 Needs & Guidelines .............................................................................................................................................................. 4
3. Project Approach & Methodology ............................................................................................................................................... 5
3.1 Introduction........................................................................................................................................................................... 5
3.2 Site Visit Preparation ............................................................................................................................................................ 5
3.3 Site Visit................................................................................................................................................................................ 5
3.4 Site Context .......................................................................................................................................................................... 5
3.5 City of London Development Objectives ............................................................................................................................... 5
3.6 Surface Analysis................................................................................................................................................................... 5
3.7 Stormwater Management Inventory ...................................................................................................................................... 5
3.8 Permeable Surface Research, Analysis & Summary............................................................................................................. 5

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3.9 Net Water Savings................................................................................................................................................................ 5
3.10 Financial Analysis............................................................................................................................................................... 6
3.11 Conclusions & Recommendations ...................................................................................................................................... 6
4. Site Context – Wonderland Power Centre.................................................................................................................................. 7
5. Surface Analysis ........................................................................................................................................................................ 9
5.1 Introduction........................................................................................................................................................................... 9
5.2 Study Area Surfaces............................................................................................................................................................. 9
5.2.1 Roofs ............................................................................................................................................................................. 9
5.2.2 Parking Lots and Low-Traffic Roadways ...................................................................................................................... 10
5.2.3 Sidewalks..................................................................................................................................................................... 11
5.2.4 Medians ....................................................................................................................................................................... 11
5.2.5 Stormwater Management Facilities .............................................................................................................................. 12
5.2.6 Other Surfaces............................................................................................................................................................. 12
6. Stormwater Management Inventory ......................................................................................................................................... 14
6.1 Introduction......................................................................................................................................................................... 14
6.2 Construction of Bradley Avenue SWM Facility.................................................................................................................... 14
6.3 Servicing Capacity of Bradley Avenue SWM Facility .......................................................................................................... 14
6.4 Subsurface Conditions........................................................................................................................................................ 16
6.5 Maintenance of the SWM Facility ....................................................................................................................................... 16
7. Permeable Surfaces Overview................................................................................................................................................. 17
7.1 Introduction......................................................................................................................................................................... 17
7.2 Permeable Asphalt ............................................................................................................................................................. 19
7.2.1 Introduction .................................................................................................................................................................. 19
7.2.2 Function and Application.............................................................................................................................................. 19

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7.2.3 Durability ...................................................................................................................................................................... 20
7.2.4 Maintenance................................................................................................................................................................. 21
7.2.5 Cost.............................................................................................................................................................................. 21
7.2.6 Benefits and Limitations ............................................................................................................................................... 21
7.3 Permeable Concrete........................................................................................................................................................... 22
7.3.1 Introduction .................................................................................................................................................................. 22
7.3.2 Function and Application .............................................................................................................................................. 23
7.3.3 Durability ...................................................................................................................................................................... 27
7.3.4 Maintenance................................................................................................................................................................. 27
7.3.5 Cost.............................................................................................................................................................................. 28
7.3.7 Supplementary Cementitious Materials ........................................................................................................................ 29
7.4 Permeable Pavement De-icing agents................................................................................................................................ 29
7.5 Green Roofs ....................................................................................................................................................................... 31
7.5.1 Introduction .................................................................................................................................................................. 31
7.5.2 Function and Application .............................................................................................................................................. 31
7.5.3 Durability ...................................................................................................................................................................... 34
7.5.4 Maintenance................................................................................................................................................................. 34
7.5.5 Cost.............................................................................................................................................................................. 35
7.5.6 Extensive Green Roofs................................................................................................................................................. 36
7.5.7 Intensive Green Roofs.................................................................................................................................................. 37
7.5.9 Public Policy................................................................................................................................................................. 38
7.6 Additional Benefits of Permeable Surfaces ......................................................................................................................... 38

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7.6.1 Urban Heat Island ........................................................................................................................................................ 38
7.6.2 LEED ........................................................................................................................................................................... 40
8. Product Analysis ...................................................................................................................................................................... 41
8.1 Introduction......................................................................................................................................................................... 41
8.2 PICP................................................................................................................................................................................... 41
8.3 Concrete & Asphalt............................................................................................................................................................. 41
8.4 Green Roofs....................................................................................................................................................................... 42
9. Net Water Savings ................................................................................................................................................................... 44
9.1 Introduction......................................................................................................................................................................... 44
9.2 Wonderland Power Centre ................................................................................................................................................. 45
9.2.1 Scenario 1a: 100% Pervious Coverage of Hard Surfaces using Permeable Asphalt or Porous Concrete and Extensive
Green Roofs ......................................................................................................................................................................... 45
9.2.2 Scenario 1b: 75% Pervious Coverage of Hard Surfaces using Permeable Asphalt or Porous Concrete and Extensive
Green Roofs ......................................................................................................................................................................... 46
9.2.3 Scenario 1c: 50% Pervious Coverage of Hard Surfaces Using Permeable Asphalt or Porous Concrete and Extensive
Green Roofs ......................................................................................................................................................................... 46
9.2.4 Scenario 1d: 25% Pervious Coverage of Hard Surfaces Using Permeable Asphalt or Porous Concrete and Extensive
Green Roofs ......................................................................................................................................................................... 46
9.2.5 Scenario 2a: 100% Pervious Coverage of Hard Surfaces using PICP and Extensive Green Roofs.............................. 49
9.2.6 Scenario 2b: 75% Pervious Coverage of Hard Surface using PICP and Extensive Green Roofs ................................. 49
9.2.7 Scenario 2c: 50% Pervious Coverage of Hard Surfaces using PICP and Extensive Green Roofs................................ 49
9.2.8 Scenario 2d: 25% Pervious Coverage of Hard Surfaces using PICP and Extensive Green Roofs................................ 50
9.3 Net-Water Savings Analysis Summary ............................................................................................................................... 50
10. Financial Analysis .................................................................................................................................................................. 52
10.1 Introduction....................................................................................................................................................................... 52

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10.2 Net Present Value & Equivalent Annual Cost.................................................................................................................... 52
10.2.1 Net Present Value and Prorated Net Present Value ................................................................................................... 52
10.3 Equivalent Annual Cost..................................................................................................................................................... 53
10.4 Product Comparisons ....................................................................................................................................................... 53
10.5 Wonderland Power Centre................................................................................................................................................ 55
10.6 Additional Economic Benefits............................................................................................................................................ 57
10.6.1 Monetary Value of Environmental Benefits................................................................................................................. 57
11. Conclusions............................................................................................................................................................................ 59
11.1 Durability........................................................................................................................................................................... 59
11.2 Net water Savings............................................................................................................................................................. 59
11.3 Financial Analysis ............................................................................................................................................................. 60
11.4 Summary .......................................................................................................................................................................... 61
12. Recommendations ................................................................................................................................................................. 63
12.1 Durability........................................................................................................................................................................... 63
12.2 Net Water Savings............................................................................................................................................................ 63
12.3 Financial Analysis ............................................................................................................................................................. 63
12.4 Additional Recommendations ........................................................................................................................................... 63
References................................................................................................................................................................................... 64
Appendices .................................................................................................................................................................................. 75
Appendix A. 1: Site Context ...................................................................................................................................................... 76
Appendix A. 2: Surface Analysis............................................................................................................................................... 77
Appendix A. 3: Stormwater Management Inventory .................................................................................................................. 78
Appendix B. 1: Product Analysis............................................................................................................................................... 79
Appendix B. 2: Net Water Savings: Calculations....................................................................................................................... 80

vi
Appendix B. 3: Financial Analysis: Calculations........................................................................................................................ 94
Appendix C: Project Timeline ................................................................................................................................................... 99

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Table of Tables
Table 1: Surface Analysis for the WPC Study Site ......................................................................................................................... 9
Table 2: Bradley Avenue SWM facility volume summary.............................................................................................................. 14
Table 3: SWM facility discharge and storage summary for varying rain events............................................................................. 15
Table 4: Factors affecting infiltration rates of permeable concrete products ................................................................................. 23
Table 5: Base storage capacity of PICP and CGP........................................................................................................................ 25
Table 6: Applications of pervious concrete ................................................................................................................................... 26
Table 7: Comparison between extensive and intensive green roof systems................................................................................. 33
Table 8: Component costs of extensive green roofs assuming an existing building with sufficient loading capacity, roof hatch and
ladder access ................................................................................................................................................................ 36
Table 9: Component cost of intensive green roofs assuming an existing building with sufficient loading capacity, roof hatch and
ladder access ................................................................................................................................................................ 37
Table 10: Comparison of feasibility parameters for various permeable products .......................................................................... 43
Table 11: Runoff coefficients........................................................................................................................................................ 45
Table 12: Comparison of runoff reductions for conventional and permeable surfaces at the WPC: Pavement and green roofs.... 48
Table 13: SWM facility volume reduction resulting from pervious surface coverage at the WPC: Pavement and green roofs....... 48
Table 14: Comparison of runoff reductions for conventional and permeable surfaces at the WPC: PICP and green roofs ........... 51
Table 15: SWM facility volume reduction resulting from pervious surface coverage at the WPC: PICP and green roofs .............. 51
Table 16: Financial comparisons of different surfaces.................................................................................................................. 55
Table 17: Financial comparisons of different surface applications at the WPC ............................................................................. 57
Table 18: Financial benefits of green roofs in Toronto, Ontario assuming 50 Million m2
of available roof space........................... 58
Table 19: Overall product comparisons ........................................................................................................................................ 62

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Table of Figures
Figure 1: The relationship between impervious and pervious area and extent of sewerage ........................................................... 2
Figure 2: Study Area ...................................................................................................................................................................... 8
Figure 3: Roof surfaces in the WPC Study Area showing a) asphalt shingles on a commercial building, b) low-sloped impervious
roof on a commercial building, and c) clay tiles on a commercial building .................................................................... 10
Figure 4: Asphalt surfaces in the WPC Study Area ...................................................................................................................... 11
Figure 5: Commercial concrete sidewalks in the WPC Study Area............................................................................................... 11
Figure 6: Medians are dispersed throughout commercial parking lots to help guide traffic and provide aesthetic relief from
dominating impervious pavements ............................................................................................................................... 12
Figure 7: Stormwater Management Pond adjacent to the WPC showing a) an inflow culvert, b) a near full pond, overflow spillway
and forebay, c) and emergency spillway ...................................................................................................................... 12
Figure 8: Other surfaces within the WPC include a) roofed shopping cart corrals and b) landscaped areas................................. 13
Figure 9: Interaction between rainwater and tradition/conventional pavement.............................................................................. 18
Figure 10: Interaction between rainwater and permeable pavement ............................................................................................ 18
Figure 11: Typical cross-section of a permeable asphalt surface ................................................................................................. 19
Figure 12: Winter performance vs. general indicators, including runoff control, pollution control, and level of integration, for
different stormwater components ................................................................................................................................. 21
Figure 13: a) PICP, b) CGP, c) PC............................................................................................................................................... 22
Figure 14: Typical installation for exfiltration................................................................................................................................. 24
Figure 15: Typical installation of porous concrete surface............................................................................................................ 26
Figure 16: Typical cross-section of a green roof........................................................................................................................... 31
Figure 17: Rural and urban heat characteristics........................................................................................................................... 39

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Glossary of Terms
Annual Precipitation – The annual total precipitation is the
sum of the rainfall and the assumed water equivalent of the
snowfall for a given year (Natural Resources Canada, 2003)
Asphalt – Also known as conventional asphalt; an
impermeable surface comprised of asphalt cement and
coarse aggregates, including stone, sand, and gravel
compacted together (Freemantle, 1999)
Baseflow – Water that, having infiltrated the soil surface,
percolates to the groundwater table and moves laterally to
reappear as surface runoff (University of Florida, 2010)
Biodegradation – The breaking down of organic and
inorganic substances by biological action, a process usually
involving bacteria and fungi (Fischel, 2001)
Bradley Avenue Stormwater Management Facility – The
Stormwater Management Facility at Wonderland Power
Centre
Concrete – Also known as conventional concrete; an
impermeable construction material comprised usually of
Portland cement, and other materials, including aggregates,
water, and chemical admixtures (ICPI, 2008)
Client – Also known as the City of London; the City;
Environmental & Engineering Services Department,
Consultant – Jovian Design; the Design team
De-icing Agent – A snow and ice control strategy for
prevention of a strong bond between frozen precipitation or
frost and a pavement surface by application of a chemical
freezing point depressant prior to or during a storm (Fischel,
2001)
Eutrophication – The enrichment of water with nutrients,
such as phosphorus resulting in the increase in numbers of
aquatic algae in the water (Fischel, 2001)
Evapotranspiration – The merging of evaporation
(movement of free water molecules away from a wet surface
into air that is less saturated) and transpiration (movement of
water vapour out through the pores in vegetation) into one
term (Christopherson, 2005)
Exfiltration – A loss of water from a drainage system as the
result of percolation or absorption into the surrounding soil
(HydroCAD, 2009)
Freeze-thaw – A weathering process in which intermittent
periods of freezing and thawing act upon a substance,
leading to its gradual breakdown by forces of water crystal
expansion and contraction (Christopherson, 2005)
Green Roof – A roof with a vegetative cover, used passively
to address environmental issues in mainly urban settings
(Kosreo & Ries, 2007)
Green Space – Areas generally planted with trees, shrubs,
herbaceous perennials and decorative grasses, rocks, and
water features; used mainly for aesthetics and recreation

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Groundwater – Water beneath the surface that is beyond
the soil-root zone; a major source of potable water
(Christopherson, 2005)
Impermeable Surfaces – Consist of surfaces which restrict
infiltration of precipitation due to decreased drainage
capacity (Shuster et al., 2005)
Infiltration – Also known as percolation; water access to
subsurface regions of soil moisture storage through
penetration of the soil surface (Christopherson, 2005)
Leadership in Energy and Environmental Design (LEED)
– A green building rating system that encourages and
accelerates the global adoption of sustainable green building
and development practices through the creation and
implementation of universally accepted performance criteria
(CaGBC, 2004)
Low-Traffic Urban Roadways – Roads and access
roadways generally characterized by low to moderate
speeds and low to moderate volumes of automobiles per day
Median – A raised structure used to organize and direct
automobile traffic, as well as to provide shade and enhance
aesthetic value to commercial parking lots (Celestian &
Martin, 2003)
Permeable Surfaces – Consist of a variety of types of
pavement, pavers and other devices that provide stormwater
infiltration while serving as a structural surface (University of
Florida, 2008)
Permeable Asphalt – Also known as porous or pervious
asphalt; an adaptation of conventional asphalt in which fine
sediments are removed, resulting in a network of
continuously linked voids to allow the passage of fluids
through the surface (Beecham, 2007; Boving, 2008)
R-value – A commercial unit used to measure the
effectiveness of thermal insulation. The R-value of the
insulator is defined as 1 divided by the thermal conductance
per inch (Rowlett, 2002)
Rational Method – An equation that postulates a
proportionality between peak discharge and rainfall intensity
(Dingman, 2002)
Return Period – The frequency with which one would
expect, on average, a given precipitation event to recur
(Cornell University, 2007)
Roof – A cover used to protect the interior and structural
components of a building from weather elements, particularly
precipitation
Sidewalk – A raised structure used to provide a suitable
transit route and safe place for pedestrians to walk
Storm Drain – An opening that leads to an underground
pipe or open ditch for transporting surface runoff, separate
from a sanitary sewer or wastewater system (Environmental
Services Water Quality Division, 2009)
Stormwater Management (SWM) Facilities – Facilities
designed to temporarily collect runoff from localized storm

xi
sewer systems after a rainfall or snowmelt event (Ministry of
Environment [MOE], 2003)
Stormwater Runoff – Excessive water, derived from
precipitation or snowmelt that ultimately reaches a drainage
area (Oke, 2006)
Toxicity – The potential of a chemical or compound to
cause adverse effects on living organisms (Fischel, 2001)
Urban Heat Island – An effect caused by the warming of
urban centres in comparison to rural areas as a result of
increasing surface characteristics which may augment
surrounding atmospheric temperatures (U.S. Environmental
Protection Agency, 2009)
Urbanization – The physical growth of urban areas as a
result of global change, in which individuals move from rural
communities to more dense urban areas (Barrow, 2003)
Water Table – The upper surface of groundwater; the
contact point between the zone of saturation and aeration in
an unconfined aquifer (Christopherson, 2005)

xii
List of Abbreviations
AAR - alkali–aggregate reaction
CaCl2 – calcium chloride
CAD – Canadian dollars
CaGBC - Canadian Green Building Council
CGP – concrete grid pavers
CMA – calcium magnesium acetate
COTA – City of Toronto Act
EAC – Equivalent Annual Cost
GTA – Greater Toronto Area
GGBFS – ground granulated blast furnace slag
ICPI – Interlocking Concrete Pavement Institute
KCl – potassium chloride
LEED – Leadership in Energy and Environmental Design
MgCl2 – magnesium chloride
NaCl – sodium chloride
NPV – Net Present Value
O&M – operation and maintenance
OEPA – Ontario Environmental Protection Act
PC – porous concrete
PICP – permeable interlocking concrete pavers
SCM – supplementary cementitious materials
SS – Sustainability Site
SWM – stormwater management
TRCA – Toronto and Region Conservation Authority
UHI – Urban Heat Island effect
USD – US dollars
WPC – Wonderland Power Centre

xiii
Executive Summary
The Engineering and Review Division, Environmental and
Engineering Services Department of the City of London has
retained Jovian Design to undertake a Permeable Surfaces
Stormwater Management Feasibility Study. The primary purpose
of this study is to evaluate the durability, net water reduction and
financial feasibility of permeable surfaces compared to
conventional materials, using the following project scope:
The Consultants will research permeable surfaces and compare
permeable products to existing conventional materials. The
purpose of this comparison is to determine the effectiveness of
each product including permeability, cost and durability while
ensuring that the development objectives of the City are met. The
Wonderland Power Centre will be assessed as a sample of this
comparison.
Peer reviewed journal articles and other literature show that
permeable surfaces are in many instances feasible for large scale
developments such as the Wonderland Power Centre. Primary
research supported these findings. Several permeable product
contractors and distributors operate within Southern Ontario and
offer products that are locally feasible in terms of cost, net-water
savings, and durability.
Comparative product analyses for local permeable pavements,
pavers, and green roof companies showed that not only are these
products readily available in Southern Ontario, but that the
lifespan and maintenance requirements of these products are
competitive with conventional pavements and roofing systems.
All permeable products proved to reduce the volume of
stormwater runoff when compared to conventional surfaces.
Within the scope of the permeable surfaces analyzed, different
product typologies offered varying levels of infiltration.
Depending on the level of integration and combination of
permeable products, the volume of water being sent to
stormwater facilities can be reduced by up to 62% in ideal
conditions. This, in turn, can represent a direct cost savings for
new developments, as the size of planned stormwater
management facilities can be reduced.
Most permeable products proved to be more expensive than
conventional materials. However, depending on the proposed
application and surface area, some permeable products are very
similar in Net Present Value and Equivalent Annual Cost to their
conventional counterparts. In the case of using porous concrete
for sidewalks, a general cost savings was discovered compared to
using conventional concrete for the same application.
Properly installed and maintained permeable pavements also
have the potential to reduce Urban Heat Island effects, improve
driving safety, encourage urban tree and plant growth, gain LEED
credits, reduce stormwater quantity and enhance water quality.
There may also be financial savings due to the benefits of
stormwater reduction, including the impact on combined sewer
overflow, improvement in air quality, reduction in direct energy
use and other environmental and social benefits such as the
aesthetic improvement of urban landscapes, and increased
property values.

PERMEABLE SURFACE STORMWATER MANAGEMENT FEASIBILITY STUDY
APRIL 2010 Page | 1
1. Introduction
1.1 General
Jovian Design (Consultants) was retained by the
Engineering Review Division, Environmental and
Engineering Services Department of the City of London
(Client) to undertake a permeable surface stormwater
management feasibility study. The intent of this project is to
evaluate the feasibility of various permeable technologies in
comparison to conventional impermeable materials, as
described in the Project Scope below, using the Wonderland
Power Centre in London, Ontario as a baseline study. This
analysis will help determine the feasibility of implementing
permeable surfaces.
Initially, a project proposal was developed by the Consultant
and refined in consultation with the Client to better reflect the
expectations of the City. Under the guidance of Dr. Omar
Ouda, the Consultants:
a) Developed a comprehensive site inventory for the
Wonderland Power Centre including site context,
surface analysis and a stormwater management
inventory
b) Conducted a literature review of permeable surfaces
to outline the function and application, durability,
maintenance, cost, and benefits and limitations of
each permeable surface type, as well as other
pertinent information
c) Contacted several local distributors and contractors
in order to gather primary information about
permeable products available in Southern Ontario
d) Analyzed the net water savings capacity of each
permeable product
e) Conducted a financial analysis of each permeable
product
f) Developed conclusions and recommendations to
reflect the findings of the Feasibility Study
This Study was completed as a result of contributions from a
number of individuals from various organizations. The
Consultants would therefore like to thank the following:
Project Scope
The Consultants will research permeable surfaces and
compare permeable products to existing conventional
materials. The purpose of this comparison is to determine
the effectiveness of each product including permeability,
cost and durability while ensuring that the development
objectives of the City are met. The Wonderland Power
Centre will be assessed as a sample of this comparison.

JOVIAN DESIGN
Page | 2
Ismail Abushehada, Ph.D., P. Eng.
City of London
Michal Kuratczyk, M.Acc.
Deloitte
Lois Burgess, P.Eng.
City of London
Connor Malloy
Duo Building Ltd.
Darcy Decaluwe
Stone in Style
Omar Ouda, Ph.D., P.Eng, PMP
University of Western Ontario
Vito Frijia
Southside Group
Denis Taves, OALA
Gardens in the Sky
Carol Hayward
City of London
Jarrett Woodward
Grand River Natural Stone Ltd.
1.2 Urbanization in the City of London
The City of London is located in the heart of south-western
Ontario, within close proximity to both Lake Huron and Lake
Erie. The City‟s population of more than 350,000 is expected
to grow steadily over the next two decades (Statistics
Canada, 2006). The City has also undergone significant
growth over the last 15 years due to a persistent
developmental strategy (City of London, 2010).
Increased impervious surface area is a consequence of
urbanization, in which there may be significant ensuing
effects on the hydrologic cycle (Shuster et al., 2005; Barnes
et al., 2002). This increasing proportion of impervious
surface creates shorter lag times between the arrival of
precipitation and consequent high runoff rates and total flow
volume (Shuster et al., 2005). As a result, a municipality‟s
sewershed or stormwater management system may be put
under increasing pressure in order to compensate for this
additional volume of runoff (Figure 1).
Figure 1: The relationship between impervious and pervious area
and extent of sewerage
Source: Shuster et al., 2005.
Increasing stress on existing stormwater infrastructure
provides incentive for municipalities like the City of London
to explore the feasibility of innovative strategies such as the
implementation of permeable surfaces.
Stormwater management facilities present an opportunity for
the City to implement strategies that address municipal
economic, social, and environmental interests. Currently
there are approximately 85 stormwater facilities in London
and over 100 more are planned for future developments.

APRIL 2010 Page | 3
These systems are expensive to build and maintain, with
facilities costing millions of dollars each.
Permeable surfaces can potentially improve the cost
effectiveness of storm water management systems, thereby
alleviating pressure on municipal financial resources. In
addition, the implementation of permeable surfaces can
result in environmental and social benefits. Increasing
urbanization and subsequent Urban Heat Island effect,
among other things, make the implementation of permeable
surfaces attractive to forward-thinking municipalities.

JOVIAN DESIGN
Page | 4
2. City of London Development Objectives
2.1 Introduction
One objective of this Study is to establish a basis for the
inclusion of permeable surface stormwater management
systems as part of the City of London Design Standards or
urban design guidelines.
Although there is a wide range of permeable products on the
North American market, not all products are suitable for the
City of London or meet the City‟s development goals and
objectives. As there are currently no specific design
standards in London pertaining to permeable surfaces, the
Consultants have developed a list of applicable development
guidelines in order to aid in the evaluation of available
permeable products.
2.2 Official Plan for the City of London
The Official Plan for the City of London contains objectives
and policies to guide physical development within the
municipality (City of London, 2010). It provides direction for
the allocation of land use and provision of municipal services
and facilities in order to promote orderly urban growth and
compatibility among land uses.
Although the Official Plan‟s primary function is to establish
policies for the physical development of the City of London, it
also has regard for relevant social, economic and
environmental matters. As such, various sections of the
Official Plan were examined in order to help determine the
City of London‟s development needs and establish support
for the implementation of permeable surfaces within the City.
2.3 Needs & Guidelines
The following provisions are necessary for parking,
roadways, sidewalks and related developments in the City of
London:
Accommodate low-level traffic and heavy vehicular
loads such as fire engines, delivery trucks, and heavy
machinery
Allow for seasonal maintenance and snow clearing
Provide easy access and use by handicapped
persons
The following objectives should be considered when
evaluating permeable surfaces:
Enhance hydrology, geomorphology and water
quality by protecting and promoting groundwater
recharge
Enhance the pedestrian environment while providing
easy access and use by all and promoting public
safety
Minimize inconvenience and damage from surface
ponding and flooding
Maximize the cost effectiveness of stormwater
management facilities
Minimize water and energy consumption through
resource conservation, landscaping and innovative
design features and servicing techniques
Promote the reuse and recycling of wastes
Protect, maintain and improve surface and
groundwater quality and quantity

APRIL 2010 Page | 5
3. Project Approach & Methodology
3.1 Introduction
The following is an account of the methodology used to
complete this Report and develop conclusions and
recommendations. A detailed project plan timeline can be
found in Appendix C.
3.2 Site Visit Preparation
Maps and satellite images were gathered from online
databases to begin the initial geographic analysis of the
Study Site.
3.3 Site Visit
The Consultants travelled to the Study Site to perform a
visual analysis of the Wonderland Power Centre for the
purposes of the Surface Analysis and Stormwater
Management Inventory (below).
3.4 Site Context
Following the Site Visit, a brief report discussing the existing
land use patterns and geographic location of the Study Site
was developed.
3.5 City of London Development Objectives
A list of applicable development objectives for the
implementation of permeable surfaces was developed based
on discussions with the Client and reviews of policies and
design standards governing development within the City of
London.
3.6 Surface Analysis
Using the City of London Public Zoning Map and the findings
from the Site Visit and Site Context, a detailed Surface
Analysis was conducted for the Wonderland Power Centre.
3.7 Stormwater Management Inventory
Functional drawings of the Wonderland Power Centre were
provided by the Clients. Using this resource and information
gathered from online databases, the Consultants assessed
the stormwater facility on the Study Site with regard to its
service capacity, lifespan, and required maintenance.
3.8 Permeable Surface Research, Analysis &
Summary
A review of the current literature on permeable surfaces,
green roofs and stormwater management approaches and
techniques was conducted. Research was primarily focused
on the typology, water retention capacity, durability and cost
of permeable surfaces and green roofs.
The Consultants also contacted several local distributors and
contractors in order to gather primary information about
permeable products available in Southern Ontario.
Findings from the Permeable Surface Research, Analysis &
Summary are found throughout this Report, most notably in
the Permeable Surface Overview and Product Analysis.
3.9 Net Water Savings
A comparative analysis of the net water savings of each type
of permeable surface and green roof was conducted using
known runoff coefficients and the calculations found within
the Surface Analysis of this Report.

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The water retention capacity of the existing Study Site and
stormwater retention pond was calculated as a baseline, and
different permeable surface coverage scenarios were
formulated.
3.10 Financial Analysis
The current capital costs, operational and maintenance
costs, and potential savings from the reduction of stormwater
management facilities as a result of each permeable surface
were compared using the Net Present Value and Equivalent
Annual Cost financial calculations.
3.11 Conclusions & Recommendations
Conclusions and recommendations were formulated based
on the findings outlined in this Report. The function and
application, durability, maintenance, cost, and benefits and
limitations of all permeable pavement and green roof options
were considered.

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4. Site Context – Wonderland Power Centre
The Wonderland Power Centre (WPC) is located in the
southeast corner of Wonderland Road and Southdale Road
in London, Ontario. Designated as a “Commercial Policy
Area” in Schedule A of the City of London Official Plan
(Appendix A) (City of London, 2006), the WPC is a fully
occupied regional shopping centre, covering approximately
20 hectares of commercial land (Southside Group, 2008).
The WPC is bound by the Westmount Estates and
Westmount Estates II high density residential buildings
(Tricar, 2010) to the east, Southdale Road to the north and
Wonderland Road to the west. The site is mirrored by a
similar commercial development, the Westwood Power
Centre, across Wonderland Road which utilizes the same
stormwater management (SWM) facility. To the immediate
south of the WPC commercial development is the “Old
Wonderland Mall” property. This area has been included as
part of the Study Site (Figure 2).
It is important to note that although the entire SWM
watershed includes the Westwood Power Centre, the Study
Site used in this Report only includes the fully developed
Wonderland Power Centre, the Old Wonderland Mall, and
the SWM facility itself.
From an aerial perspective, the WPC can be divided into
four general types of hard surfaces: paved parking lots
and/or roadways; concrete sidewalks; roofs, and;
landscaped areas. As seen in the map below, the majority of
the WPC interior is paved asphalt parking spaces or
roadways. The perimeter of the site is lined with commercial
developments (the majority of which have low-sloped roofs),
and there are small landscaped medians dispersed
throughout the site. Perhaps most notably, the south-eastern
corner of the Study Site contains the stormwater
management facility that collects runoff for the entire Study
area.
With the exception of the soft, landscaped surfaces sparsely
located throughout the Site, the Study Area is composed
entirely of hard surfaces that do not allow water to permeate
into the underlying soil. This is explored in further detail in
the following section.
It is important to note that the WPC is only intended to
provide a baseline analysis for this Feasibility Study.

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Figure 2: Study Area
LEGEND
Entire Study Area
WPC & Old
Wonderland Mall
Commercial
Areas
Stormwater
Management
Facility
Stormwater
Management
Watershed
Modified from: City of London, 2010

APRIL 2010 Page | 9
5. Surface Analysis
5.1 Introduction
The Study Area covers approximately 220,000 m2
of land
(Table 1), of which approximately 70% is comprised of
impermeable surfaces. In other words, more than two-thirds
of all precipitation that falls on the site may begin to flow as
urban runoff, with minimal, if any vegetative buffers to
intercept it. This is a substantial amount of surface flow, and
therefore requires a catchment area (i.e., SWM facility) of
sufficient size to store the excess water and mitigate further
runoff. The cost to build such structures generally requires a
significant amount of funds for municipalities and, ultimately,
taxpayers (AECOM, 2009).
The primary impermeable surfaces examined in this section
of the Report include roofs, parking lots and low-traffic
roadways, and sidewalks. Other surfaces that will be
examined include medians, green spaces, and temporary
structures (e.g., shopping cart corrals). Calculations for this
analysis were completed through on-site investigations and
satellite interpretation using a modified City of London Public
Zoning Map (Appendix A).
5.2 Study Area Surfaces
5.2.1 Roofs
The primary function of roofs is to protect the interior and
structural components of a building from weather elements,
particularly precipitation. Roofs within the Wonderland
Power Centre are the second most prevalent surface,
making-up approximately 20% of the entire Study Area.
Approximately 17% of the Study Area is comprised of low-
sloped, commercial roofs, whereas sloped or pitched roofs
represent approximately 2% of the Study Site.
Table 1: Surface Analysis for the WPC Study Site
The low-sloped roofs are generally sealed with an
impervious asphalt layer, while pitched roofs are generally
covered with impervious asphalt shingles (e.g., Loblaw
Superstore) or other highly impervious materials such as
clay tiles (e.g., Angelo‟s Italian Bakery and Deli). In both
instances, precipitation is directed from the roof to a
drainage system consisting of gutters, downspouts, and
piping, and ultimately to the surface below (either
impermeable asphalt or cement, or permeable grass
surfaces which allow infiltration). Vegetated green roofs may
act as an intermediate step to this process, intercepting
Surface Analysis for the Wonderland Power Centre
Surface Type Area (m2
) Area (%)
Low-sloped Roofs 37,550 17
Sloped Roofs 5,193 2
Parking Lots/Roadways 96,161 44
Sidewalks 14,812 7
Medians 9,987 5
SWM Pond 42,983 19
Others (e.g., Green Space;
Temporary Structures)
14,098 6
TOTAL 220,784 100

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precipitation and helping to reduce runoff from reaching the
SWM facility (VanWoert et al., 2005).
Figure 3: Roof surfaces in the WPC Study Area showing a) asphalt shingles on a commercial building, b) low-sloped impervious roof on a
commercial building, and c) clay tiles on a commercial building
5.2.2 Parking Lots and Low-Traffic Roadways
The principal function of parking lots is to accommodate a
steady volume of visitors and their automobiles. Parking lots
within the WPC site are the most significant surface
typology, composing more than 40% of the entire Study
Area. Part of this percentage includes a series of low-traffic
roadways connecting the parking lots together. Generally
located around the peripheries of parking lots and buildings,
these features are primarily coated with impermeable
asphalt, but may also include concrete pavement as well.
Porous pavements, including permeable asphalt, porous
concrete, Permeable Interlocking Concrete Pavers (PICP)
and grid pavers, may be used to divert urban runoff from
SWM facilities, as precipitation is able to pass through the
paved surfaces and recharge groundwater sources or the
water table (Beecham, 2007; Boving, 2008).
a b c

APRIL 2010 Page | 11
Figure 4: Asphalt surfaces in the WPC Study Area
5.2.3 Sidewalks
The main function of sidewalks is to provide a suitable transit
route and safe place for pedestrians to travel, by separating
them from vehicular traffic. Raised sidewalks within the
Wonderland Power Centre represent an overall surface
composition of close to 7% of the entire Study Area.
Sidewalks are generally composed of impermeable concrete
pavement which prevents percolation of precipitation and
snow melt (Bean et al., 2007). Permeable pavers and porous
concrete may be used to help alleviate the stress of surface
runoff on SWM facilities by increasing infiltration rates on
site. Although they make up a small percentage of the total
area of the WPC, sidewalks may be the most feasible
surface to change, while acting as a consistent penetrable
buffer.
Figure 5: Commercial concrete sidewalks in the WPC Study Area
5.2.4 Medians
The primary function of medians is to organize and direct
automobile traffic, as well as to provide shade and enhance
the aesthetic value of commercial parking lots (Celestian &
Martin, 2003). Medians within the Wonderland Power
Centre are the least prevalent surface, making-up slightly
more than 4% of the entire Study Area. They are sparsely
located within each parking section, and generally contain
trees, shrubs, herbaceous perennials, ornamental grasses,
and in some cases decorative stone or mulches. These
decorated medians are not considered to be “hard” surfaces,
and therefore may effectively catch and store incident
precipitation due to their vegetative nature and soil-based
structure. However, due to their elevation (i.e., about 4 to 6

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inches off the ground), medians generally do not help reduce
stormwater runoff or flow over the parking lots.
Figure 6: Medians are dispersed throughout commercial parking lots
to help guide traffic and provide aesthetic relief from
dominating impervious pavements
5.2.5 Stormwater Management Facilities
The main function of a SWM facility is to store runoff from
precipitation and snow melt, which may otherwise lead to
flooding or erosion, and adversely affect water quality (MOE,
2003). The SWM facility used to mitigate runoff at the
Wonderland Power Centre makes up nearly 20% of the
entire Study Area. More detail on this facility can be found in
the Stormwater Inventory section of this Report.
Figure 7: Stormwater Management Pond adjacent to the WPC
showing a) an inflow culvert, b) a near full pond, overflow
spillway and forebay, c) and emergency spillway
5.2.6 Other Surfaces
Landscaped green spaces within the Wonderland Power
Centre site represent slightly more than 6% of the Study
Area. These spaces are generally composed of trees,
a
b c

shrubs, herbaceous perennials and decorative grasses,
rocks, and maintained grass lawns. Although their function
is mainly for aesthetic and recreational purposes, urban
green spaces may help alleviate the problem of surface
runoff by increasing infiltration rates and acting as a
penetrable buffer (Benedict & McMahon, 2002).
Landscaped green spaces may be intensified to provide a
more significant role or function, both as an aesthetic tool
and as a buffer, especially in commercial and residential
zones where impermeable surfaces generally dominate.
Temporary structures, including roofed shopping cart corrals
and seasonal greenhouses are also present within the Study
Area.
Figure 8: Other surfaces within the WPC include a) roofed shopping
cart corrals and b) landscaped areas

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6. Stormwater Management Inventory
6.1 Introduction
The WPC is wholly serviced by the Bradley Avenue
Stormwater Management Facility within the Pincombe Drain
catchment area (Appendix A). A Stormwater Management
Inventory is required to assess the present condition and
required maintenance of the SWM facility at the Wonderland
Power Centre. As such, functional designs, entitled Final
Stormwater Management Report for the Bradley Avenue
Stormwater Management Facility were obtained from the
City of London Engineering and Review Division, and used
to assess the servicing capacity, present condition and
required maintenance of the SWM facility.
6.2 Construction of Bradley Avenue SWM Facility
The total projected cost for the Bradley Avenue SWM
facility was $2,456,660 of which the cost for
construction of inlet/outlet sewers was $636,660
(AECOM, 2009).
Prior to construction, on-site siltation and erosion
control measures were taken in order to prevent the
transportation of eroded soils off-site into
downstream properties or watercourses. These
measures included the installation of 140m of regular
duty silt fences and 300m of heavy duty silt fences.
A sediment trap of approximately 70m x 20m x 1m
was constructed adjacent to the SWM Facility, to
store sediment deposition.
6.3 Servicing Capacity of Bradley Avenue SWM Facility
The City of London averages 987mm of precipitation per
year (Environment Canada, 2010).
As illustrated in Table 2, the Bradley Avenue SWM facility
has a total stormwater retention capacity of 45,238m3
.
Generally speaking, the facility has a total permanent
volume of 7.500m3
, with a drawdown time of 72 hours
(Development Engineering, 2005).
Table 2: Bradley Avenue SWM facility volume summary
Bradley Avenue SWM Facility Volume Summary
Water Quality Volume Required Provided
Permanent pool volume per
hectare based on protection
level and imperviousness (MOE)
115 m3
/ha 118 m3
/ha
Total Permanent pool volume 5615 m3
7500 m3
Total SWM Facility Volume – 45238 m3
Baseflow and Erosion Volume Required Provided
Total storage volume per hectare 200 m3
/ha 160 m3
/ha
Total baseflow and erosion
volume
12685 m3
10147 m3
Source: Development Engineering, 2005

Table 3 summarizes the return period of flooding as used in
the Bradley Avenue SWM facility modeling. The stormwater
discharge into the SWM facility, for return periods of 2, 5, 10,
25, 50, 100 and 250 years has been tabulated and the
volume corresponding to the respective flooding events has
been calculated (Development Engineering, 2005).
In the event of a 250 year storm (6 hour duration), 26,524 m3
of the SWM facility will be utilized. This number represents
approximately 59% of the total volume of the facility at
45,238 m3
. Thus, the anticipated single-event volume
utilization from the SWM facility is less than the maximum
available storage volume (Development Engineering, 2005).
Table 3: SWM facility discharge and storage summary for varying
rain events
Discharge and Storage Summary for 2-250 Year Rainfall Events
Return
Period
Discharge
into SWM
facility
(m3
/s)
Discharge
from
SWM
facility
(m3
/s)
Storage
volume
utilization
(m3
)
Pond
elevation/depth
(m)
2 year 5.90 0.28 13271 266.08
5 year 7.68 0.85 16380 266.27
10 year 8.86 1.51 17713 266.35
25 year 10.08 2.24 19288 266.44
50 year 11.05 2.42 20429 266.51
100
year
11.72 2.56 21571 266.58
250
year
15.01 3.10 26524 266.86
Source: Development Engineering, 2005
However, given that the SWM facility carries a constant
volume, frequent storm events can surpass the maximum
capacity, leading to the submergence of the existing
discharge outlets and a subsequently slow release of water
from the SWM facility (Development Engineering, 2005).

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6.4 Subsurface Conditions
A subsurface analysis was carried out at the WPC site in
order to install standpipes and the groundwater table was
discovered to be 7.9m to 8.1m below the surface
(Development Engineering, 2005). According to Brown
(2008), these depths are suitable for the installation of
permeable surfaces, which require a groundwater table of at
least 1.1m to 1.5m from the surface.
6.5 Maintenance of the SWM Facility
The maintenance responsibilities for the Bradley Avenue
SWM facility are separated into general maintenance,
sediment maintenance and sediment disposal (Development
Engineering, 2005).
General maintenance is carried out three or four times a
year. The activities include weed control, grass cutting and
outlet pipe opening maintenance. Sediment maintenance is
carried out when the sediment removal efficiency is reduced
by 5%. Sediment disposal is carried out after a sediment
chemical analysis is completed. The Ministry of Environment
guidelines for Use at Contaminated Sites in Ontario and the
Ontario Environmental Protection Act (OEPA), Regulation
347, Schedule 4 Leachate Test, Ref. 15 provide the
applicable guidelines for determining sediment disposal
options (Development Engineering, 2005).
Inspection is carried out at least once per month during dry
weather, and a Sediment & Erosion Control Maintenance &
Monitoring Report is completed (Development Engineering,
2005).
Annual maintenance costs for the SWM facility at the WPC
is estimated at $20,000 per year (Weber, 2010).

7. Permeable Surfaces Overview
7.1 Introduction
The level of urbanization is rising; by 2030 it is expected that
83% of people in developed countries will live in urban areas
(Mentens, Raes & Hermy, 2005). Urbanization results in the
displacement of cropland, grassland and forests by the
implementation of impervious surfaces. This greatly
intensifies stormwater runoff, diminishing groundwater
recharge and enhancing stream channel and river erosion
(Mentens, Raes & Hermy, 2005).
Permeable surfaces are surfaces which allow water to
percolate or travel through their structure into the underlying
ground layer, thereby relieving pressures on traditional
stormwater management systems (SWITCH, 2007). The
advancement of new technologies has brought many new
permeable products onto the market; including porous
asphalt, permeable concrete, green roofs and other
emerging technologies. If properly installed and maintained,
permeable pavements are typically designed to handle as
much as 70-80% of annual rainfall (Metropolitan Area
Planning Council, 2010).

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Figure 9: Interaction between rainwater and tradition/conventional pavement
Modified from: Sansalone et al., 2008, p. 667)
Traditionally-paved surfaces do not allow for the natural
infiltration of water into the underlying soil for the purposes of
groundwater recharge (Sansalone, Kuang & Ramieri, 2008).
Rather, rainfall is carried over the surface of pavements as
runoff (Figure 9), and must be captured using municipal
stormwater management infrastructure. In addition to the
negative environmental impacts associated with
impermeable surfaces (i.e., the movement of pollutants into
natural systems and increasing runoff peaks and volumes),
impermeable surfaces are also a costly economic
expenditure (Sansalone et al., 2008; Gilbert & Clausen,
2006). As urbanization increases, so too does the need for
increased stormwater infrastructure. The development of a
new individual stormwater management facility for a city the
size of London can cost anywhere between just over $1
million (CAD) to just under $7 million (CAD); including land
acquisition, construction of ponds, and necessary piping
systems (AECOM, 2009).
Permeable surfaces, on the other hand, serve as more
environmentally conscious, low-impact development
materials for rainwater runoff control (Figure 10) (Sansalone,
Figure 10: Interaction between rainwater and permeable pavement
Modified from: Sansalone et al., 2008, p. 667)

et al., 2008). Although some surfaces have higher porosities
than others, they all work to restore the in situ hydrology of a
site by reducing runoff, filtering and treating infiltrating runoff
and reducing thermal pollution and temperature (Sansalone
et al., 2008). By reducing the rate and quantity of
stormwater runoff, permeable pavements reduce the
demand on stormwater treatment facilities (Landers, 2008),
thereby reducing costs for capital infrastructure,
maintenance and operation (SWITCH, 2007).
7.2 Permeable Asphalt
7.2.1 Introduction
Conventional asphalt is comprised of asphalt cement and
coarse aggregates, including stone, sand, and gravel
compacted together (Freemantle, 1999). Traditionally, this
media consists of impermeable substances which do not
allow precipitation or surface runoff to infiltrate into the soil or
rock beds. A novel solution to impervious asphalt was first
developed in the 1970s, in which fine sediments (e.g., sand
with a grain size less than 0.075 mm in diameter) were
removed, resulting in a network of continuously linked voids
to allow the passage of fluids through the pavement surface
and ultimately to groundwater sources or the water table
(Beecham, 2007; Boving, 2008).
7.2.2 Function and Application
Walker (2006) suggests that the permeable asphalt surface
(e.g., approximately 5 to 10 cm in depth with 15-25% voids
or pore space) should be generally underlain by a top filter
course (e.g., 5 cm of 1.3 cm crushed stone aggregate), a
reservoir course (determined by the average storage
volume, structural capacity, or frost depth; usually an 20 or
23 cm minimum with aggregates between 4 and 7.5 cm in
size with 40% voids is recommended), an optional bottom
filter course, filter fabric (e.g., geotextile fabric) and subgrade
material consisting of larger aggregates that acts as a
temporary storage capacity to hold the collected water
(Walker, 2006). Figure 11 shows a typical cross-section of a
permeable asphalt surface.
Figure 11: Typical cross-section of a permeable asphalt surface
Source: Fancher & Townsen, 2003
Many factors must be taken into account before a project
can be proposed or designed using permeable asphalt,
including local soil characteristics, local topography, climate,
and traffic loading (Brattebo & Booth, 2003). For instance, it
is recommended that permeable asphalt pavement be used
on sites with gentle slopes (e.g., surface grade less than
5%), permeable soils (i.e., well drained or moderately well
drained), and relatively deep water table and bedrock levels
(Gunderson, 2008; Beecham, 2007).
Conventional asphalt is largely used as a material to
construct highways, roadways, airfields, and parking lots.
Alternatively, permeable asphalt pavement is appropriate for

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low-traffic applications such as walkways, low-traffic streets,
and along highway shoulders (Freemantle, 1999; Brattebo &
Booth, 2003).
7.2.3 Durability
The lifespan of a parking lot situated in a northern climate,
and made from conventional pavements is approximately 15
years (EPA, 2009). A properly designed, installed, and
maintained permeable asphalt pavement, on the other hand,
may have a lifespan of 20 to 30 years (Gunderson, 2008).
The regional climate of Southwestern Ontario, and
specifically London, presents many obstacles to the
effectiveness of permeable asphalt pavement due to cold
weather. For instance, Backstrom and Bergstrom (2000)
found that at freezing point, the infiltration capacity of porous
asphalt was about 40% lower (7.4 mm/min) than that near
20o
C (19 mm/min) due to ice formation within the pores.
The authors also found that exposure to snowmelt conditions
(i.e., freeze-thaw) over a two day period further reduced this
capacity up to 90%. As a result, typical snowmelt conditions
for porous asphalt may only yield an estimated 1-5 mm/min
infiltration capacity (Backstrom & Bergstrom, 2000;
Stenmark, 1995). However, several confounding variables
found during experimentation may be at fault for the overall
poor performance. Firstly, the asphalt pieces were taken
from a field site which had been in operation for two years.
Secondly, the asphalt was not cleaned; nor were the pore
spaces unclogged before testing. Thirdly, no apparent de-
icing agents of any sort were used during experimentation,
which may have melted snow and ice more quickly, allowing
water to effectively infiltrate the media.
Despite the results of this Study, many researchers maintain
that porous asphalt pavement performs relatively well in cold
weather climates compared to conventional design
(Gunderson, 2008; Roseen & Ballestero, 2008; Roseen et
al., 2009; Backstrom and Viklander, 2000). These
researchers argue that porous asphalt, and other low impact
development designs, have a high level of functionality
during winter months and that frozen filter media, generally,
do not reduce performance. Figure 12 shows winter
performance of different stormwater components.

Figure 12: Winter performance vs. general indicators, including
runoff control, pollution control, and level of integration,
for different stormwater components
Source: Backstrom and Viklander, 2000
7.2.4 Maintenance
Due to the nature of porous asphalt pavement, regular
inspection for surface clogging must be undertaken,
especially after large storm events, which may also increase
sandy discharge (Beecham, 2007). In cases of clogged or
reduced surface porosity, the pavement can be cleaned by a
vacuum sweeper or pressure washer 2 to 4 times per year to
avoid build-up of debris, and to prevent potential decreases
in infiltration capacity (Bean et al., 2007; Balades et al.,
1995).
For large commercial developments, however, this implies
an additional cost that should be taken into consideration
when comparing product types.
Dust and sand tends to clog the pores of porous asphalt
surfaces and severely restrict percolation through the top
layer of the system (Bean et al., 2007; Balades et al., 1995).
It stands to reason that these surfaces may not be suitable
candidates for areas adjacent to partially landscaped
locations where significant erosion may take place, or
jurisdictions which use sand, and even salt, as a de-icing
agent in winter. A liquid de-icer is therefore recommended as
it drains out with the snow and ice during melting, leaving the
porosity of the pavement largely intact (Walker, 2006).
7.2.5 Cost
The cost of porous asphalt pavement installation is similar in
cost to conventional asphalt, and one of the least expensive
compared to the other permeable surfaces (Boving, 2008). It
is estimated that the cost for porous asphalt pavement is
approximately $5.50 to $10.76 (USD) per metre squared
(EPA, 2009). However, the underlying stone bed is usually
more expensive than those found in a conventional sub-
base, due to the greater depths of aggregates required
(Beecham, 2007).
Special training or techniques are not generally required for
application of porous asphalt, as the laying process is similar
to that of conventional asphalt (Walker, 2006).
7.2.6 Benefits and Limitations
The key advantage of permeable asphalt is that it retains
stormwater onsite, which may decrease surface runoff with
low peak discharge (Bean et al., 2007; Rushton, 2001). It
may also act as a potential water quality treatment process
by intercepting the contaminants of urban stormwater runoff

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prior to infiltration into soil (Beecham, 2007; Brattebo &
Booth, 2003; Bean et al., 2007).
Another possible benefit of using porous asphalt in cold
weather climates is that melted water infiltrates through the
media before it freezes, which may cause fewer problems
with slipperiness and black ice related accidents, for
example, during cold nights (Backstrom & Bergstrom, 2000).
Parking lots and roads tend to be sources of water pollution
because of their extensive impervious surfaces, in which
most precipitation that falls becomes urban runoff. Motor
vehicles are a constant source of pollutants, the most
significant being gasoline, motor oil, polycyclic aromatic
hydrocarbons (found in the combustion by-products of
gasoline, as well as in asphalt sealants used to maintain
parking lots), and heavy metals (Bean et al., 2007; Rushton,
2001; Boving et al., 2008). According to a cold climate study
by Backstrom and Viklander (2000), cold vehicle engines
produce 2 to 8 times more potentially harmful particles than
does a warm engine, which may accumulate on
impermeable surfaces and be subject to runoff, with
implications for water contamination.
Another study by Boving et al. (2008) suggests that porous
asphalt is effective at removing organic and metal
contaminants. However, permeable asphalt surfaces, which
allow liquid infiltration, may lead to possible ground
contamination within the surface of the parking lot. Although
this process can filter the water, contaminants may seep
directly into groundwater, especially where there is
groundwater abstraction downstream for drinking water
(Howard & Beck, 1993; Legret & Colandini, 1999).
7.3 Permeable Concrete
7.3.1 Introduction
Concrete in the form of permeable interlocking concrete
pavers (PICP), concrete grid pavers (CGP) and porous
concrete (PC) (Figure 13) is commonly used to increase
surface infiltration rates, thereby mitigating stormwater from
conventional stormwater systems (Bean, Hunt, &
Bidelspach, 2007a). Infiltration rates depend on a number of
factors, including the type of permeable concrete product
that is applied, soil infiltration rate, and installation of the
permeable concrete product (i.e. the aggregate material that
is used as a filler, and the size and type of sub-base that is
installed) (Table 4) (Bean et al., 2007a).
Figure 13: a) PICP, b) CGP, c) PC
Source: Bean et al., 2007b

Results from runoff studies indicate that permeable concrete
pavements may not only reduce runoff, but also eradicate
runoff entirely under certain rainfall depths, intensities,
maintenance conditions, antecedent conditions and designs
(Bean et al., 2007b).
Table 4: Factors affecting infiltration rates of permeable concrete products
Factors Affecting Infiltration Rates of Permeable Concrete Products
Product
Site
(m2
)
Slope
(%)
Soil
Thickness of Permeable Surface
(mm)
Filler Base
Base
(mm)
SIR
(mm/h)
CGP 630 0.5
Kalmia sandy
soil
90
Coarse grade
sand
Yes; sand 50 580
PC 370 0.33
Seagate fine
graded sand
200 NA No NA 230
PICP 740 0.4
Bay Meade
sandy soil
76 NA
Yes; stone &
gravel
275 20 X 1013
PICP 120 NA
Loamy sand
soil
76 NA
Yes; stone &
gravel
275 40 X 1013
SIR = Surface Infiltration Rate; Source: Bean et al., 2007a
PICP is defined as concrete block pavers that, when in
place, create voids located at the corners and midpoints of
the pavers, allowing water to infiltrate through an aggregate
material (Bean et al., 2007b). CGP is defined as concrete
blocks with inner voids between the blocks that permit water
to infiltrate in the same way as PICP. PC is defined as
altered standard concrete, as fine aggregate has been
removed from the standard mix, permitting interconnected

JOVIAN DESIGN
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void spaces to form during curing, thus allowing water to
infiltrate through the material (Bean et al., 2007b).
7.3.2.1 Function and Application of PICP and CGP
The primary difference between permeable pavers and
conventional pavers is base materials and void space (Bean
et al., 2007b; Unilock, 2009). Permeable paver systems use
crushed, angular, open-graded aggregate base materials
that have a void space or porosity of approximately 40%.
Base storage capacities depend on a number of factors
including rainfall and base depth (Table 5) (Unilock, 2009).
The proper installation of the base is very important to the
optimal function of PICP and CPG systems (Smith, 2006).
Figure 14 illustrates the appropriate installation of a typical
exfiltration system including base compositions and
measurements. This system fully exfiltrates, by infiltrating
water directly into the base and extruding it to the soil.
Overflows are managed through perimeter drainage to
swales, bio-retention areas or storm sewer inlets. Partial
exfiltration systems are less common than full exfiltration
systems and include drainage by perforated pipes. In this
case, excess water is drained from the base by pipes to
sewers or a stream (Smith, 2006).
Figure 14: Typical installation for exfiltration
Source: Uni-EcoLocTech, 2008
The application of PICP and CGP products depend on the
specific material that is being used as well as the location of
the project. Unilock, a company that sells permeable
pavers, manufactures its products to meet the ASTM C936
standard which allows the product to support semi-truck
traffic, heavy-traffic and high-load environments (Unilock,
2009). The application of Unilock products varies greatly.
Over 107.6 million metres squared of Unilock permeable
pavers have been installed throughout Canada and the U.S.
Applications include parks and municipal commons,
commercial parking and vehicular areas, government and
municipal facilities, streets and streetscapes, stadiums,
condominiums and others (Unilock, 2009). Because of the
structural integrity of CGP, this material is intended for light-
duty use such as over-flow parking areas, being occasionally

used in parking lots, and in access to emergency lanes
(Smith, 2006).
Table 5: Base storage capacity of PICP and CGP
Base Storage Capacity of Permeable Interlocking Concrete Pavers and Concrete Grid Pavers
Criteria
Rainwater Harvest
Volume
Base Storage
Capacity
Surplus/(Deficit)
Storage
Rainfall
(mm/hr)
Surface Area
(m2
)
Base Depth
(cm)
Void
Space
(m3
) (m3
) (m3
)
%
Used
25 4,047 30 40% 103 493 391 20.8%
25 4,047 46 40% 103 740 637 13.9%
89 4,047 30 40% 360 493 134 72.9%
89 4,047 46 40% 360 740 380 48.6%
12 4,047 61 40% 520 986.5 473 52.1%
188 4,047 46 40% 761 740 (21) 102.8%
Source: Unilock, 2009
7.3.2.2 Function and Application of PC
PC is a paste composed of water and cementitious materials
that forms a thick coating around aggregate particles
(Tennis, Leming, & Akers, 2004). Void space is created by
adding little or no sand which results in a system that is
highly permeable and drains quickly. The hardened
concrete contains between 15% and 25% voids that typically
allow flow rates of approximately 34 mm/s, although it can
be much higher (Figure 15) (Tennis, et al., 2004).

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Figure 15: Typical installation of porous concrete surface
Source: National Ready Mixed Concrete Association, 2010
PC can be applied in a variety of settings. It can be used in
parking lots, tennis courts, greenhouses and as pervious
base layers under heavy duty pavements (Table 6) (Tennis
et al., 2004). Properly installed PC can achieve strengths in
excess of 20.5 MPa and flexural strengths of more than 53.5
MPa. This strength is more than sufficient for most low-
volume pavement applications, including high axle loads for
garbage truck and emergency vehicles such as fire trucks
(Tennis et al., 2004). As PC matures, its compressive
strength increases (Park & Tia, 2003). Special mix designs,
structural designs and placement techniques can be altered
to accommodate more demanding applications (Tennis et
al., 2004).
Table 6: Applications of pervious concrete
Applications of Porous Concrete
Low-volume pavements Artificial reefs
Residential roads, alleys, and
driveways
Slope stabilization
Sidewalks and pathways Well linings
Parking lots Tree grates in sidewalks
Low water crossings Foundations/floors for
greenhouses, fish hatcheries,
aquatic amusement centres,
and zoos
Tennis courts Hydraulic structures
Subbase for conventional
concrete pavements
Swimming pool decks
Patios Pavement edge drains
Walls (including load-bearing) Groins and seawalls
Source: Tennis et al., 2004

7.3.3 Durability
7.3.3.1 Durability of PICP
PICP is particularly durable and has the capacity to
withstand high traffic areas and climatic uncertainty (Toronto
and Region Conservation Authority [TRCA], 2007). A study
by the TRCA (2007) indicated that permeable pavement
continued to function normally throughout the winter months
during winter rain events, with minor amounts of infiltrate
measures even during very cold periods.
7.3.3.2 Durability of CGP
CGP is recommended for light-duty use, thus applications
vary (Pavers by Ideal, 2005). Certain CGP products have
the capacity to withstand harsh winter climates and are
“snow-plough safe.” Freeze-thaw conditions have no
demonstrated effect on certain CGP products (Pavers by
Ideal, 2005).
7.3.3.3 Durability of PC
PC is often criticized for its vulnerability to freeze-thaw
conditions (Tennis et. al., 2008). However, freeze-thaw
resistance depends on the saturation level of the voids in the
concrete at the time of freezing. Because PC drains rapidly,
saturation is often prevented from occurring. In fact,
evidence suggests that snow-covered pervious concrete
melts quicker as voids in the material allow snow to thaw
more quickly than conventional pavements. Different factors
improve durability of PC in freeze-thaw conditions. For
example, entrained air in the PC paste can dramatically
improve freeze-thaw protection. Placement also plays an
important role as specific installation is recommended in
freeze-thaw environments (Tennis et. al., 2008).
PC can be susceptible to the effects of aggressive chemicals
in soils or water, such as acids and sulphates (Tennis et. al.,
2008). If isolated from high-sulphate soils and groundwater,
PC can be used. Abrasion resistance is also a concern as
PC has a rough surface texture and open structure. PC can
be particularly problematic where snowploughs are used to
clear pavements although studies indicate that PC can allow
snow to melt faster thus requiring less ploughing (Tennis et.
al., 2008).
7.3.4 Maintenance
7.3.4.1 Maintenance of PICP, CGP and PC
Clogging can occur as a result of fine particle accumulation
in the void spaces of permeable pavements (Bean, Hunt,
Bidelspach & Burak, 2004). The rate of clogging increases
as more fine particles (fines) are trapped since smaller
particles trap larger particles. In most cases, clogging
reduces surface infiltration rates. Clogging can be limited,
however, through regular maintenance, either by a vacuum
sweeper or pressure washing thereby improving surface
infiltration rates from unmaintained infiltration rates (Bean et
al., 2007b; Smith, 2006). Clogging can also be limited
through strategic site placement away from disturbed soil
areas.
One study concluded that maintenance was vital to
sustaining high surface infiltration rates of CGP in particular
(Bean et al., 2007b). Without maintenance, the median
average infiltration rate of CGP was 4.9 cm/h; while with
maintenance, the median infiltration rate was 8.6 cm/h (Bean
et al., 2007b).

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The study also concluded that the selected site of permeable
pavement applications was a significant factor in preserving
high surface infiltration rates (Bean et al., 2007b). In
particular, locating PICP and PC away from disturbed soil
areas was of great importance in maintaining high surface
infiltration rates. The authors of this particular study also
found that permeable pavements installed in sandy soil
environments maintained relatively high surface infiltration
rates, regardless of pavement age or type (Bean et al.,
2007b).
Bean et al. (2007b) suggest that a storage layer improves
runoff reduction potential. Keeping the permeable surface
free of fine particles, performing regular maintenance and
construction on sandy, in situ soils may also increase runoff
reduction potential.
In climates where snow removal equipment is employed,
damage can occur to PICP and CGP. This may require the
replacement of damaged blocks thereby increasing
maintenance costs.
7.3.5 Cost
7.3.5.1 Cost of PICP, CGP, and PC
The cost of permeable concrete pavement varies according
to location, distributor, and scope of project (among other
factors). For example, PICP is generally more expensive
than conventional asphalt or concrete pavements that rely
on a stormwater collection pond (Interlocking Concrete
Pavement Institute [ICPI], 2008). PICP may be cost-effective
in a new development where regulations limit impervious
cover and space is limited. Because PICP and other
permeable pavements may not require a collection pond as
large as impervious-paved surfaces, space can be used
more efficiently (ICPI, 2008).
PICP and CPG have the capacity to remove pollutants,
improving the quality of exfiltrate (Tennis et al., 2008). The
material allows the rainfall to percolate into the ground where
soil chemistry and biology are able to “treat” the polluted
water naturally. This results in the reduction or elimination of
stormwater retention areas. Also, “groundwater and aquifer
recharge is increased, peak flow through drainage channels
is reduced and flooding is minimized” (Tennis et. al., 2008,
p.4). PICP is also easy to replace as individual pavers can
be removed in the event of damage (Park & Tia, 2003). This
results in lower replacement costs and lessens the negative
environmental impact of large scale product replacement
(Hirshorn, 2010).
PC has the capacity to remove pollutants from infiltrate at
high rates (Park & Tia, 2003). Pollutant removal rates are
variable as water purification can be affected by the size of
aggregate and void content in the PC paste. One study
indicates that PC composed of a smaller size of aggregate
and a higher void content greatly removes total nitrogen (T-
N, mg/l) and total phosphorous (T-P, mg/l) from the test
water in comparison to PC pastes with a larger size
aggregate and a lower void content. Smaller sized
aggregate and higher void content increase the surface area
of the concrete‟s porosity. The composition of the PC paste
can largely affect the ability of the material to remove
pollutants (Park & Tia, 2003).

Permeable surfaces should not be used in locations with
high pollutant loads. These locations include commercial
nurseries, recycling facilities, fuelling stations, industrial
storage, marinas, some outdoor loading facilities, public
works yards, hazardous materials generators (if containers
are exposed to rainfall), vehicle service and maintenance
areas and vehicle and equipment washing and steam
cleaning facilities (Hirshorn, 2010). Permeable paving
should also not be used in high traffic and/or high speed
areas as permeable paving has lower load-bearing capacity
that conventional pavement (Hirshorn, 2010).
7.3.7 Supplementary Cementitious Materials
The National Ready Mixed Concrete Association (2008)
claimed that the construction industry is committed to
continuous environmental improvement through process
innovation and product standards that lead to reduced
environmental impact. One method of improving product
standards is through the mixing of Portland cement with
supplementary cementitious materials (SCMs) for various
uses.
Bouzoubaâ and Foo (2005) contend that SCMs, including fly
ash, ground granulated blast furnace slag (GGBFS), silica
fume and natural pozzolans can be mixed with Portland
cement. These blended cements are less energy intensive
and made with by-products or wastes. Therefore, they
reduce the solid waste burden on landfills and offer
performance benefits for certain applications (Committee E-
701 Materials for Concrete Construction, 2001). One of the
main objectives of increasing the use of SCMs in concrete
production is to reduce the release of CO2 associated with
the production of each cubic meter of concrete (Bouzoubaâ
& Fournier, 2005). SCMs were used mainly due to their low
costs and performance-enhancing aspects. Fly ash is used
in various concrete applications because of improvement in
workability, reduction of heat of hydration, increased water
tightness and ultimate strength, and enhanced resistance to
sulphate attack (especially in western Canada) and alkali–
aggregate reaction (AAR) throughout Canada (Bouzoubaâ &
Fournier, 2005).
The use of SCMs in the cement and concrete industries can
render benefits in engineering, economic, and ecological
terms (Malhotra & Mehta, 1996). Engineering benefits of the
incorporation of SCMs into a concrete mixture include
improvement in the workability and the reduction of the
water. This mixing enhances the ultimate strength,
permeability, and durability to chemical attack along with an
improved resistance to thermal cracking.
In terms of residential application, concrete is used in
basement walls and floors, driveways, steps, sidewalks and
a small amount of concrete products such as paving blocks,
retaining walls, and masonry blocks. Specifically, SCMs
have proven to be very effective in producing durable,
freeze-thaw tolerant sidewalks (Bouzoubaâ & Fournier,
2005).
7.4 Permeable Pavement De-icing agents
In many northern countries, such as Canada and the USA,
one of the main de-icing agents of choice for safe driving
conditions in municipal areas is common salt (sodium
chloride) because of its cost effectiveness (Liu et al., 2006).
Urbanization leads to increases in impervious surfaces and

JOVIAN DESIGN
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complex systems, such as roads, parking lots, and sidewalks
that receive chemical de-icer to keep them free of ice and
snow during winter (Daley et al., 2009). As a result of these
larger surfaces, additional road salts are required which may
adversely affect soil and vegetation systems, human health,
as well as the quality of water systems (e.g., groundwater
and streams) due to increased levels of Cl-
(Williams et al.,
2005; Williams et al., 1999).
The Greater Toronto Area alone applies more than 100,000
tonnes of salt each winter (Williams et al., 1999) and
approximately 5 million tonnes of sodium chloride are
consumed each year in Canada for de-icing roles
(Environment Canada and Health Canada, 2001). If high
enough concentrations of these road salts reach
groundwater zones, contamination can occur and negatively
affect drinking water quality, fresh water systems, and
aquatic ecosystems (Ramakrishna & Viraraghavan, 2005).
De-icing salts, particularly NaCl contribute ions to the soil,
altering pH and the soil‟s chemical composition, which may
lead to vegetative stress and disrupt plant function
(Bogemans et al., 1989; Guntner & Wilke; Trombulak &
Frissell, 2000). NaCl is also an environmental concern
because of its toxicity to aquatic organisms; its alterations to
soil structure and decreased permeability (Ramakrishna &
Viraraghavan, 2005; Fischel, 2001); and its adverse effects
on human health (Environment Canada and Health Canada,
2001).
The main human impact of ingesting large amounts of salt is
hypertension leading to cardiovascular disease, which could
account for thousands of deaths a year in Canada and the
USA (Feig & Paya, 1998). In the past few years, high levels
of sodium and chloride (>2000 mg/L) have been found in
many shallow groundwater wells in and around the GTA
where urbanization is greater than 80% (Williams et al.,
1999). In general, only wells or reservoirs near salt-treated
surfaces or salt storage facilities are most likely to become
susceptible to salt infiltration, whereby road salts can enter
drinking water supplies by migrating through soil into
groundwater or by runoff and drainage directly into surface
water (Werner & diPretoro, 2006).
Due to concerns of clogged pores by sand and salt, a liquid
de-icer is therefore recommended for use on permeable
pavements as it drains out with the snow and ice during
melting, leaving the porosity of the pavement largely intact
(Walker, 2006). However, less research has been devoted
towards liquid de-icers, including CaCl2, KCl, and MgCl2
(Ramakrishna & Viraraghavan, 2005). Generally the chloride
ions of these substances have similar environmental impacts
as rock salt (NaCl), but have been found to present less
toxicity to aquatic organisms, as well as having a limited
impact on human health (Fischel, 2001).
Another option for snow and ice removal on permeable
pavement is the liquid form of calcium magnesium acetate
(CMA) which may provide the most environmentally friendly,
although a more expensive alternative to sodium chloride,
while leaving the porosity of the pavement largely intact.
CMA is an organic de-icing agent which may largely be
broken down by biodegradation (Fischel, 2001; Ramakrishna
& Viraraghavan, 2005). There is, however, some concern
that the acetate-based de-icer has the potential to cause

oxygen depletion in rivers, streams, and lakes; however, it is
hoped that the agent breakdown before such an occurrence
(Fischel, 2001; Ramakrishna & Viraraghavan, 2005). There
is also some debate over pH alterations and the corrosive
potential caused by the agent (Ramakrishna &
Viraraghavan, 2005). Due to CMA containing phosphorous
and nitrogen, eutrophication may occur to nearby water
bodies, and as a result adversely affect aquatic ecosystems
(Fischel, 2001).
7.5 Green Roofs
7.5.1 Introduction
Roof surfaces account for a large portion of impervious
cover in urban areas. Establishing vegetation on roof-tops,
known as green roofs, is one method of recovering lost
green space that can aid in mitigating stormwater runoff (van
Woert, et al., 2005).
A green roof, i.e., a roof with a vegetative cover (Figure 16),
is one passive technique that can be used to address
environmental issues in an urban setting (Kosareo & Ries,
2007). Green roofs have been a standard construction
practice in many countries for hundreds, if not thousands of
years, mainly due to the excellent insulative qualities of the
combined plant and soil layers (sod) (Peck & Kuhn, n.d.). In
the cold climates of Iceland and Scandinavia, sod roofs
helped to retain heat, while in warm countries such as
Tanzania, green roofs keep buildings cool. Canadian
examples of early green roofs, imported by the Vikings and
later the French colonists, can be found in the provinces of
Newfoundland and Nova Scotia (Peck & Kuhn, n.d.).
Figure 16: Typical cross-section of a green roof
Source: Kosareo & Ries, 2007
Green roofs are an emerging strategy for mitigating
stormwater runoff. They offer numerous benefits such as:
Stormwater mitigation; insulation for buildings; an increase in
the life span of a typical roof by protecting the roof
components from exposure to ultraviolet rays, extreme
temperatures and rapid temperature fluctuations; filtration of
harmful air pollutants; an aesthetically pleasing environment
to live and work in; habitat for a range of organisms, and; the
potential to reduce Urban Heat Island effect (van Woert et
al., 2005). However, many consider stormwater runoff
mitigation to be the primary function of green roofs due to
the prevalence of impervious surfaces in urban areas (van
Woert et al., 2005). Furthermore, green roofs have the
potential to improve thermal performance of a roofing system
through shading and evapotranspiration, thus reducing a
building‟s energy demand for space conditioning (Kiu &
Baskaran, 2003).

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Green roofs help mitigate the impact of high-density
commercial and residential development by restoring
displaced vegetation (van Woert et al., 2005). Studies have
shown that green roofs can absorb water and release it
slowly over a period of time as opposed to conventional
roofs where stormwater is immediately discharged (van
Woert et al., 2005).
There are two basic types of green roof systems – extensive
and intensive (Peck & Kuhn, n.d.; Kosareo & Ries, 2007).
They are differentiated mainly by the cost, depth of growing
medium and the choice of plants. (Table 7) below provides
an in-depth look at the advantages and disadvantages of
both systems.
Green roofs are thought to have a number of benefits
compared to a conventional roof. An extensive green roof
can reduce stormwater runoff by 60%, whereas an intensive
green roof by 85% (Kosareo & Ries, 2007). On a yearly
basis, rainfall-retention capability of green roofs ranges from
75% for intensive green roofs to 45% for extensive green
roofs (Mentens, Raes & Hermy, 2006).

Table 7: Comparison between extensive and intensive green roof systems
Comparison between Extensive and Intensive Green Roof Systems
EXTENSIVE GREEN ROOF INTENSIVE GREEN ROOF
Thin growing medium; little or no irrigation; stressful conditions
for plants; low plant diversity.
Deep soil; irrigation system; more favourable conditions for plants;
high plant diversity; often accessible.
Advantages:
• Lightweight; roof generally does not require reinforcement.
• Suitable for large areas.
• Suitable for roofs with 0 - 30° (slope).
• Low maintenance and long life.
• Often no need for irrigation and specialized drainage systems.
• Less technical expertise needed.
• Often suitable for retrofit projects.
• Can leave vegetation to grow spontaneously.
• Relatively inexpensive.
• Looks more natural.
• Easier for planning authority to demand as a condition of
planning approvals.
Advantages:
• Greater diversity of plants and habitats.
• Good insulation properties.
• Can simulate a wildlife garden on the ground.
• Can be made very attractive visually.
• Often accessible, with more diverse utilization of the roof (i.e., for
recreation, growing food, as open space).
• More energy efficiency and storm water retention capability.
• Longer membrane life.
Disadvantages:
• Less energy efficiency and storm water retention benefits.
• More limited choice of plants.
• Usually no access for recreation or other uses.
• Unattractive to some, especially in winter.
Disadvantages:
• Greater weight loading on roof.
• Need for irrigation and drainage systems requiring energy, water,
materials.
• Higher capital & maintenance costs.
• More complex systems and expertise.
Source: Peck & Kuhn (n.d.), p. 5

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7.5.3 Durability
The average life span of conventional roofing systems is 10-
20 years (Kosareo & Ries, 2007) depending on the quality of
the roof. Extensive green roof systems have an expected life
span of approximately 40 years; double that of a “high-
grade” conventional roof. In Europe, the development of
green roofs has gone on for decades; research shows that
green roofs can be maintained for about 50 years. In the
case of intensive green roofs, substantial vegetation can be
grown because of additional layers of soil. The intensive
green roofs also improve the roof life span and provide
additional insulation; however, the decision to include them
in the design of a project needs to be made early so that the
proper structural membranes can be selected to support the
additional weight that accompanies this kind of construction
(Kosareo & Ries, 2007).
A generic extensive green roof is able to significantly reduce
the daily temperature fluctuation of a roof surface in warmer
months (spring and summer) (Liu & Baskaran, 2003). In the
case of a conventional roofing system, diurnal temperature
fluctuations create thermal stresses, affecting the system‟s
long-term performance and its ability to protect a building
from water infiltration. However, a green roof enhances the
thermal performance of the roof by providing shading,
insulation and evaporative cooling. In the winter months,
once the snow coverage is established, the heat flow
through both conventional roofs and green roofs is the same,
as snow coverage provides good insulation and stabilized
heat flow through the roof (Liu & Baskaran, 2003).
The green roof is also more effective in reducing heat gain in
spring/summer than heat loss in fall/winter (Liu & Baskaran,
2003). This is because the green roof can reduce heat gain
through shading, insulation and evapotranspiration. This is
effective on summer evenings, but not in winter when the
growing medium is frozen and the improved insulation and
decreased radiation heat loss effects are dominated by snow
coverage (Liu & Baskaran, 2003).
7.5.4 Maintenance
The extensive green roof was developed for use on
contemporary residential buildings in the early 1900s by a
German roofer (Köhler et al., 2002). In many German cities
these roofs were built as a form of fire protection. This type
of roof proved to be very durable and almost totally free of
maintenance (Köhler et al., 2002). Building owners however,
are hesitant to consider the use of a green roof due to its
increased initial costs and uncertainties in the construction
and maintenance of such roofs. Studies on life cycle
assessment of green roofs find that the life cycle cost of
extensive roofs are less than conventional roofs, although
intensive systems have a higher life cycle cost (Kosareo &
Ries, 2007).
As mentioned earlier, conventional roofs require
maintenance and replacement over 10-20 years. For
extensive green roofs, maintenance is only required for plant
growth and waterproofing. For intensive green roofs, the
system requires the same additional layers as an extensive
roof, only the growing medium layer is greater in depth, thus
maintenance is same as the extensive roofs (Kosareo &
Ries, 2007).

Regular maintenance inspections should be scheduled as
for any conventional roof installation. Plant maintenance
ranges from two to three yearly inspections to check for
weeds or damage, to weekly visits for irrigation, pruning and
replanting (Peck & Kuhn, n.d.). The maintenance of the
waterproofing membrane can be complicated since the
green roof system completely covers the membrane.
Although the green roof protects the membrane from
puncture damage and solar radiation, thus doubling its life
span, leaks can still occur at joints. The replacement time for
green roof membranes is 30-50 years, longer than
conventional roofs (Peck & Kuhn, n.d.).
7.5.5 Cost
The initial cost of a green roof is high as installation costs
remain at a premium, thereby preventing widespread
investment in green roof technology (Clark, Adriaens, &
Talbot, 2008). The benefits of green roofs are mainly
increased roof longevity, reduced stormwater runoff, and
decreased energy consumption. The Net Present Value
(NPV) of an extensive green roof system in comparison to a
conventional roof is approximately 20% to 25% less than the
NPV for a conventional roof over 40 years (Clark et al.,
2008).
If stormwater, energy, and air pollution benefits are
quantitatively integrated into an economic model, the
additional upfront investment in green roof technology is
recovered at the time when a conventional roof would be
replaced. If the value of improved air quality is quantitatively
considered, improved air quality results in a mean NPV for
the green roof that is approximately 25% to 40% less than
the mean NPV of a conventional roof. This valuation
scenario reveals that over 40 years, green roofs cost less
than conventional roofs (Clark et al., 2008).

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7.5.6 Extensive Green Roofs
Table 8: Component costs of extensive green roofs assuming an existing building with sufficient loading capacity, roof hatch and ladder access
Component Costs of Extensive Green Roofs
Component Cost Notes and Variables
Design & Specifications
5% - 10% of total
roofing project cost
The number and type of consultants required depends on the size and complexity of
the project.
Project Administration &
Site Review
2.5% - 5% of total
roofing project cost.
The number and type of consultants required depends on the size and complexity of
the project.
Re-roofing with root-
repelling membrane
$100.00 - $160.00/m2
.
Cost factors include type of existing roofing to be removed, type of new roofing
system to be installed, ease of roof access, and nature of flashing required.
Green Roof System
(curbing, drainage layer,
filter cloth, growing
medium, decking and
walkways)
$55.00 - $110.00/m2 Cost factors include type and depth of growing medium, type of curbing, and size of
project.
Plants $11.00 - $32.00/m2
Cost factors include time of year, type of plant, and size of plant - seed, plug, or pot.
Installation/Labour $32.00 - $86.00/m2
Cost factors include equipment rental to move materials to and on the roof (rental of
a crane could cost as much as $4,000.00 per day), size of project, complexity of
design, and planting techniques used.
Maintenance
$13.00 - $21.00/m2
For the first 2 years
only
Costs factors include size of project, timing of installation, irrigation system, and size
and type of plants used.
Irrigation System $21.00 - $43.00/m2 Optional, since the roof could be watered by hand. Cost factors include type of
system used.
Source: Peck& Kuhn (n.d.) p. 15

7.5.7 Intensive Green Roofs
Table 9: Component cost of intensive green roofs assuming an existing building with sufficient loading capacity, roof hatch and ladder access
Component Costs of Intensive Green Roofs
Component Cost Notes and Variables
Design & Specifications
5% - 10% of total
roofing project cost
The number and type of consultants required depends on the size and
complexity of the project.
Project Administration & Site Review
2.5% - 5% of total
roofing project cost.
The number and type of consultants required depends on the size and
complexity of the project.
Re-roofing with root-repelling membrane
$100.00 -
$160.00/m2
Cost factors include type of existing roofing to be removed, type of new
roofing system to be installed, ease of roof access, and nature of
flashing required.
Green Roof System (curbing, drainage
layer, filter cloth, growing medium,
decking and walkways)
$160.00 -
$320.00/m2
Cost factors include type and depth of growing medium, type and
height of curbing, type of decking, and size of project. (Cost does not
include freestanding planter boxes.
Plants
$54.00 -
$2,150.00/m2
Cost is completely dependent on the type and size of plant chosen,
since virtually any type of plant suitable to the local climate can be
accommodated (one tree may cost between $200.00 and $500.00).
Irrigation System $21.00 - $43.00/m2
Cost factors include type of system used and size of project.
Guardrail/Fencing $65.00 - $130.00/m
Cost factors include type of fencing, attachment to roof, and size of
project / length required.
Installation/Labour $85.00 - $195.00/m2 Cost factors include equipment rental to move materials to and on roof,
size of project, complexity of design, and planting techniques used.
Maintenance $13.50 - $21.50/m2 Costs factors include size of project, irrigation system, and size and type
of plants used.
Source: Peck & Kuhn (n.d.), p. 16

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The two most important benefits of green roofs are improved
stormwater retention and reduction of Urban Heat Island
effect (Peck & Kuhn, n.d.). Green roofs also provide other
services, such as ecological advantages, discussed below.
Stormwater retention is the basic and most important benefit
of green roofs (Peck & Kuhn, n.d.). First, the plants capture
and hold rainwater. Water is then stored in the growing
media and is released through evapotranspiration, thus
reducing the flow of stormwater onto the ground. A heavily
vegetated green roof can hold 10-15 cm of water (Peck &
Kuhn, n.d.).
A stormwater retention study for the City of Portland,
Oregon, found that if half of all the buildings in the downtown
area had green roofs, an estimated 250 million litres of water
would be retained annually. The study indicated that
stormwater discharge would be reduced by 11% to 15%
(Peck & Kuhn, n.d.).
Green roofs are also known to filter out fine, airborne
particulate matter as the air passes over the plants (Peck &
Kuhn, n.d.). Based on data from trees, it was estimated that
about 4,000 kg of dirt can be removed from the air per year
(2 kg/m2
of green roof) (Peck & Kuhn, n.d.).
Green roofs can be specifically designed to mimic
endangered ecosystems, such as the Great Lakes Region
habitat in Canada (Peck & Kuhn, n.d.). Thusly, extensive
green roof systems can become home to sensitive plants as
well as bird species that prefer to nest on the ground (Peck
& Kuhn, n.d.).
7.5.9 Public Policy
In order to properly quantify the environmental benefits of
green roofs, policies that affect green roofs may first need to
be changed in order to overcome perceived hurdles. Clark
et al. (2008) identify two strategies that have the potential to
resolve the price discrepancy between green and
conventional roofs: (i) proper valuation of infrastructure costs
via stormwater fees, and (ii) market-based tradable permit
schemes for contribution to impaired local waterways. In
terms of air pollution, direct incentives or programs that
incorporate green roofs as an abatement technology into
existing regional air pollution emission allowance markets
could further reduce the economic deterrence of green roofs
(Clark et al., 2008).
The City of Toronto Act (COTA) of 2006 provided Toronto
City Council with the authority to pass a bylaw requiring and
governing the construction of green roofs (City of Toronto,
2010). Toronto is the first city in North America to have a
bylaw to require and govern the construction of green roofs
on new development. It was adopted by Toronto City Council
in May 2009, under the authority of Section 108 of the City of
Toronto Act. The bylaw requires green roofs on new
commercial, institutional and residential development with a
minimum gross floor area of 2,000 square metres as of
January 31, 2010 (City of Toronto, 2010).
7.6 Additional Benefits of Permeable Surfaces
7.6.1 Urban Heat Island
Urban Heat Island (UHI) effect refers to the warming of
urban centres in comparison to rural areas as a result of high
density impermeable surface cover and other infrastructure

that increases surface and atmospheric temperatures
(Figure 17) (U.S. Environmental Protection Agency, 2009).
Recently, there has been some concern about the heating
effects due to an increasing area of dark-coloured
impermeable surfaces (e.g., conventional asphalt) (Asaeda
& Ca, 2000). For instance, the UHI effect occurs due to the
prevalence of low albedo surfaces that absorb incident
radiation and prevent the radiation from being reflected back
to the atmosphere (Oke, 2006). Because there are
insufficient pores in impermeable surfaces, day time
evaporation is not as effective in impermeable surfaces as
permeable surfaces (Golden & Kaloush, 2005). Without
evaporation, latent energy may not be liberated, which is
generally required to cool the surrounding air (Asaeda & Ca,
2000). As a result, overall ambient air temperatures increase
in comparison to the adjacent rural areas where
evapotranspiration is more prevalent (Oke, 2006).
Figure 17: Rural and urban heat characteristics
Source: Ngan, 2004
According to Golden and Kaloush (2005) the UHI can
negatively impact the sustainability of a region by increasing
the dependence on mechanical cooling, which requires
electrical consumption (producing greenhouse gas
emissions and using significant amounts of water
resources), and may raise the cost of living for residents.
The UHI can also have an impact on heat-related illnesses,
especially from elevated night-time temperatures due to
increased heat storage and release (Golden & Kaloush,
2005).
In terms of asphalt, however, Asaeda and Ca (2000) suggest
that there may be only a slight difference in UHI between
traditional asphalt and that which is more porous in nature.
The large pore size of the porous material still leaves the
pavement rather dry, in which little evaporation is observed
at the surface. Further research may be required to get a
better understanding of how thermal environments are
affected by porous media. In terms of PICP and CGP,
proper selection of materials and colours can help reduce
UHI effect (Unilock, 2009). PC can also lower the UHI effect
as the light colour of PC absorbs less heat from solar
radiation than darker pavements, and the open pore
structure of PC pavement stores less heat. In addition, PC
allows adjacent trees to receive more air and water (Park &
Tia, 2003).
Green roofs intercept solar radiation which would be
reflected by dark roof surfaces, thereby reducing the
greenhouse effect (Peck & Kuhn, n.d.; Ball, 2008). A study
conducted in Chicago concluded that if, over a period of ten
years, all of the buildings in the City were retrofitted with

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green roofs, the annual savings would amount to
approximately $100,000,000 (USD) from reduced cooling
load requirements in all buildings (Peck & Kuhn, n.d.).
7.6.2 LEED
A particularly attractive benefit for using permeable surfaces
as opposed to conventional surfaces is the opportunity to
gain Leadership in Energy and Environmental Design
(LEED) credits. For instance, according to the Canadian
Green Building Council (CaGBC, 2004), porous pavement
systems, including pervious cement and asphalt, vegetative
roofs and permeable pavers, have the potential to earn up to
four Sustainability Sites (SS) category credits toward LEED
certification. Systems can earn one credit for reducing water
quantity and runoff (e.g., SS Credit 6.1 Stormwater
Management, Rate and Quality); one for improving water
quality (e.g., SS Credit 6.2 Stormwater Management,
Treatment); and two for mitigating Urban Heat Island effects
(e.g., SS Credit 7.1 Heat Island Effect, Non-roof; SS Credit
7.2 Heat Island Effect, Roof). On the other hand, permeable
pavements and surfaces can also add credits in the
Materials and Resources category (e.g., Credit MR 2.1 –
5.2) that already exists for conventional surface materials
(NAPA, 2008; CaGBC, 2004). The importance of converting
to these innovative types of surfaces is to encourage and
accelerate global adoption of sustainable green building and
development practices in order to mitigate and prevent
further negative environmental impacts (CaGBC, 2004).

8. Product Analysis
8.1 Introduction
In order to gather accurate data of permeable surface
products, local distributors and contractors were contacted
for information regarding specific characteristics of
permeable products including: Permeability, durability and
cost of locally supplied permeable products. The distributors
and contractors who participated in the analysis were
generally eager to provide information about a range of
products. In terms of cost, when ranges were provided, the
average of the range was calculated. In some cases, upon
the advice of distributors, the lower portion of the range was
utilized in order to reflect economies of scale for large
commercial development projects. The products in this
analysis meet the City of London needs and development
guidelines and are thereby considered practical options for
commercial application. The following analysis is divided
among permeable surface typology, including: PICP,
Permeable Asphalt and Porous Concrete, and Green Roofs
(Table 10).
8.2 PICP
The PICP products, Eco-Optiloc, Eco-Priora, and Subterra,
provide three practical options for PICP implementation. In
terms of the installation of PICP, it is assumed that the
products are installed with a modern paving machine, the
Toro H 88, which is locally owned and operated. Due to the
scope of commercial applications, the utilization of a paving
machine is appropriate. The employment of the Toro H 88
not only increases installation efficiency but decreases
labour costs, thus reducing overall costs (Decaluwe, 2010).
Unilock and Permacon offer PICP products that provide high
levels of permeability and durability while maintaining
reasonable costs. The products are quite similar in terms of
permeability and durability, differing in cost largely as a
result of aesthetics (Woodward, 2010). Because PICP
products require similar maintenance, the use of a vacuum
or sweeping agent 1 to 2 times per year, the cost of
maintenance and operation is the same for each product.
In terms of the cost of installation and subbase materials, the
durability and retention capacity of all products are similar.
The Eco-Optiloc and Subterra products are quite
comparable in all categories despite the fact that they are
supplied by two different companies. The major difference
between the two products is the cost of the stone. The cost
of Eco-Priora is more than double the cost of the other two
products.
8.3 Concrete & Asphalt
The characteristics of conventional concrete and asphalt are
compared to porous concrete and permeable asphalt to
illustrate the differences in permeability, durability and cost.
The costs include the price of the product, the price of the
subbase, and installation of both products. For this survey,
Jovian Design consulted with Lafarge Canada and Coco
Asphalt Engineering. The total costs including installation
and subbase of porous concrete are high in comparison to
permeable asphalt. However, the differences in lifespan are
noteworthy, affecting total costs. Maintenance costs are
approximately the same among the conventional and
permeable products as vacuums and sweepers should be

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employed 1 to 2 times per year. The lifespan of the products
also vary between 20 and 30 years.
8.4 Green Roofs
A range of green roofs are presented in order to
demonstrate the variety of options that exist. The green roof
products that are denoted with an asterisk (*) include the
price of the supply, delivery and installation of complete
green roof assemblies. In all cases the assembly includes a
root barrier, a drainage layer component, a filter fabric,
growing medium (soil), vegetation and an automatic
irrigation system. The cost includes typical contractor
attendance at required site meetings, the provision of
submittal documentation, bonding, permits and insurance.
The price also includes a standard two-year maintenance
program including condition monitoring and reporting,
weeding, plant replacement, debris and drain cleaning,
irrigation adjustment and winterizing in the overall price of
the product. The price does not include general roof
insulation or waterproofing, roof drains, roof drain inspection
chambers, railings/guards, benches or other furniture,
decking, fall protection devices, flood testing or a permanent
leak detection system. The price does not include paver or
ballast materials surrounding the areas of vegetation, the soil
containment features, whether those are restraint edging,
curbing, planters of guard-height planter walls (Taves, 2010).
The Floradrain products are priced to include the cost of the
entire system, therefore consisting of the product costs and
installation, as well as 1 to 2 years of maintenance service.
The cost of the product supplied by Duo Building Ltd.
includes the material costs, shipping, equipment rental,
labour, miscellaneous costs and HST. The LiveRoof product
cost includes material costs and installation.
In most cases the maintenance costs for the first 1 to 2 years
are in included in the initial costs. This practice is an
industry standard employed by green roof contractors to
ensure the stability and longevity of the green roof system.
Maintenance costs largely depend on the depth of the soil
and the plants used in green roof applications. Therefore,
intensive roof maintenance costs are higher than extensive
roof maintenance costs. The runoff coefficient also depends
on the depth of the soil and the plants that are used.
Permeability depends on the depth of the soil and the plants
that are used. Therefore, extensive roofs have a higher
runoff coefficient than intensive roofs. The durability of
green roofs is on average the same.

Table 10: Comparison of feasibility parameters for various permeable products
Permeable Product Comparisons
Product Cost Operation and Maintenance Durability Runoff Coefficient
PICP
Eco-Optiloc $82.7/m2
$10.76/m2
/year 25 years 0.25
Eco-Priora $126.5/m2
$10.76/m2
/year 25 years 0.25
Subterra $80.87/m2
$10.76/m2
/year 25 years 0.25
Concrete
Porous Concrete $170/m3
$0.07/m2
/year 30 years 0.4
Conventional Concrete $215/m3
$0.07/m2
/year 30 years 0.9
Asphalt
Permeable Asphalt $95/m3
$0.11/m2
/year 20 years 0.4
Conventional Asphalt $95/m3
$0.09/m2
/year 25 years 0.9
Green Roof
Extensive
Floradrain FD 25 $107.6/m2
$1.35/m2
/year 40 years 0.5
$1.35/m2
/year 40 years 0.5
LiveRoof $150.64/m2
$1.35/m2
/year 40 years 0.5
Duo Building Ltd. $206.67/m2
$1.35/m2
/year 40 years 0.5
Soprema Taiga* $161.45/m2
$1.35/m2
/year 40 years 0.5
Sedum Master* $193.75/m2
$1.35/m2
/year 40 years 0.5
LiveRoof* $322.90/m2
$1.35/m2
/year 40 years 0.5
Intensive
Connon Nursery* $269.10/m2
$8.07/m2
/year 40 years 0.3
$8.07/m2
/year 40 years 0.3
*The cost for these products includes the first two years of maintenance.

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9. Net Water Savings
9.1 Introduction
A simplified version of the Rational Method was employed in
order to analyze the net-water savings of conventional and
permeable products. This method is acceptable for use in
this analysis as it is commonly applied in the calculation of
urban drainage (Dingman, 2002).
The imperviousness of various surface materials and their
relationship to subsequent runoff due to rainfall events was
evaluated in order to estimate a reduction in the quantity of
runoff (%) observed under several scenarios. These
scenarios were contrasted with conventional surfaces to
evaluate the effectiveness of installing permeable
pavements and extensive green roofs.
The modified calculations were derived from the Interlocking
Concrete Paving Institute (ICPI) (2007) and based on the
following equations:
A runoff coefficient of 0.9 was applied to asphalt pavement,
concrete pavement, and conventional roofs (Dingman,
2002); 0.5 was applied to green roofs with thicknesses of 6-
10 cm and slopes less than 15o
(Ngan, 2004); 0.25 was
applied to permeable interlocking concrete pavement (ICPI,
2007); and 0.4 was applied to porous asphalt, concrete, and
grid pavers (ICPI, 2008) (Table 11).
It is assumed that each runoff coefficient is averaged due to
the varying nature and range of storm intensities and
durations in any specific study area (ICPI, 2005). According
to ICPI (2007), it is important to account for these variables
because the prevalence of storms (either by close or greater
spacing) and the level of saturation of the soil will affect the
overall runoff coefficient.
It is reasonable to assume that the reduction in runoff is
directly proportionate to the runoff coefficient. For the
purposes of this Report, the results of the calculations also
provide a rough estimate of a proportional reduction in the
total SWM facility volume. Finally, it was assumed that
evaporation was not significant, and that rainfall either
becomes runoff (i.e., reaches a stormwater management
facility) or does not (i.e., infiltrates).

Table 11: Runoff coefficients
Runoff Coefficients for Different Surface Typologies
Surface
Runoff
Coefficient
% Runoff
per m2
%
Infiltration
per m2
Conventional Asphalt 0.9 90% 10%
Conventional
Concrete
0.9 90% 10%
Conventional Roof 0.9 90% 10%
Permeable Asphalt 0.4 40% 60%
Porous Concrete 0.4 40% 60%
PICP 0.25 20% 75%
Extensive Green Roof 0.5 50% 50%
9.2 Wonderland Power Centre
The current pavement on the WPC Study Site is gently
sloped and underlain with relatively sandy soils with
satisfactory infiltration capacity, while the groundwater table
is at an acceptable level from the surface for adequate
infiltration (Development Engineering, 2005). The physical
conditions of the WPC Study Site provide an excellent
context to perform pavement comparisons. For the purpose
of identifying the most feasible permeable surface, several
scenarios were considered.
In the following scenarios, the assumption has been made
that either permeable pavements (asphalt or concrete) or
permeable interlocking concrete pavers will be used as a
substitute ground material. All scenarios include the use of
extensive green roofs. As such:
The first group of scenarios (1a, 1b, 1c, 1d) includes
the use of permeable asphalt or porous concrete and
extensive green roofs.
The second group of scenarios (2a, 2b, 2c, 2d)
includes the use of PICP and extensive green roofs.
The volume of water utilized by the WPC SWM facility was
calculated using a ratio of the Study Site‟s drainage area to
the total drainage area. Since the WPC Study Site
encompasses approximately 39% (22 hectares) of the total
drainage area (56 hectares), it is assumed the volume of the
Bradley Avenue SWM Facility that is utilized by the Study
Site is 39% of 45,238 m3
, or 17,643m3
.
9.2.1 Scenario 1a: 100% Pervious Coverage of Hard Surfaces
using Permeable Asphalt or Porous Concrete and Extensive
Green Roofs
In this scenario permeable asphalt or porous concrete and
extensive green roofs are completely (i.e., 100%) substituted
for conventional surfaces, with runoff coefficients ranging
from 0.4 to 0.5.
As seen in Table 12, if only extensive green roofs are
installed (with no ground material substitution) a runoff
reduction of approximately 12% of the total Study Site would
be observed. Alternatively, if only sidewalks are replaced by
porous concrete or permeable asphalt, a runoff reduction of
more than 5% for the total area would be generated. Finally,
if only the parking lots are completely replaced by porous
concrete or permeable asphalt, a runoff reduction of
approximately 34% for the total area would be observed. By
substituting 100% of all surfaces, a 51% reduction in runoff
can be achieved.

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Under these conditions, the maximum volume of the SWM
facility could therefore be reduced from 45,238m3
to
36,293m3
, a reduction of 8,945m3
(Table 13).
9.2.2 Scenario 1b: 75% Pervious Coverage of Hard Surfaces
using Permeable Asphalt or Porous Concrete and Extensive
Green Roofs
In this scenario permeable asphalt or porous concrete, and
green roofs are substituted for 75% of conventional surfaces,
with runoff coefficients ranging from 0.4 to 0.5.
reduction of approximately 9% for the total Study Site would
4% for the total area would be generated. Finally, if only the
parking lots are partially replaced by porous concrete or
permeable asphalt, a runoff reduction of approximately 25%
for the total area would be observed. By substituting 75% of
all hard surfaces, a 38% reduction in runoff could be
achieved.
to
38,534m3
(Table 13).
9.2.3 Scenario 1c: 50% Pervious Coverage of Hard Surfaces
Using Permeable Asphalt or Porous Concrete and Extensive
Green Roofs
extensive green roofs are substituted for 50% of
conventional surfaces, with runoff coefficients ranging from
0.4 to 0.5.
reduction of approximately 6% of the total Study Site would
approximately 3% for the total area would be generated.
Finally, if only the parking lots are partially replaced by
less than 17% for the total area would be observed. By
substituting 50% of all hard surfaces, a 25% reduction in
runoff can be achieved.
Under these conditions, the volume of the SWM facility could
therefore be reduced from 45,238m3
to 40,757m3
, a
reduction of 4,481m3
(Table 13).
9.2.4 Scenario 1d: 25% Pervious Coverage of Hard Surfaces
Using Permeable Asphalt or Porous Concrete and Extensive
Green Roofs
extensive green roofs are substituted for 25% of
0.4 to 0.5.
more than 1% for the total area would be generated. Finally,

if only the parking lots are partially replaced by porous
concrete or permeable asphalt, a runoff reduction of
runoff could be achieved.
to
42,997m3
(Table 13).

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Table 12: Comparison of runoff reductions for conventional and permeable surfaces at the WPC: Pavement and green roofs
Full calculations for Table 12 can be found in Appendix B
Table 13: SWM facility volume reduction resulting from pervious surface coverage at the WPC: Pavement and green roofs
Runoff Reductions Resulting from Pervious Surface Coverage at the WPC: Pavement and Green Roofs
Percent Runoff Reduction for:
SURFACE 100% Pervious Coverage 75% Pervious Coverage 50% Pervious Coverage 25% Pervious Coverage
(Scenario 1a) (Scenario 1b) (Scenario 1c) (Scenario 1d)
Permeable Asphalt Parking Lots 33.6 25.2 16.8 8.4
Porous Concrete Sidewalks 5.2 3.9 2.6 1.3
Extensive Green Roofs 11.9 9.0 6.0 3.0
Total Runoff Reduction 50.7 38.0 25.4 12.7
Stormwater Facility Volume Reduction Resulting from Pervious Surface Coverage at the WPC: Pavement and Green Roofs
Reduction in Stormwater Facility Volume for:
SURFACE
100% Pervious
Coverage (m3
)
75% Pervious Coverage
(m3
)
(m3
)
(m3
)
Permeable Asphalt Parking Lots 5,928 4,446 2,964 1,482
Porous Concrete Sidewalks 917 688 459 229
Extensive Green Roofs 2,100 1,588 1,059 529
Total Reduction 8,945 6,704 4,481 2,241

9.2.5 Scenario 2a: 100% Pervious Coverage of Hard Surfaces
using PICP and Extensive Green Roofs
In this scenario permeable interlocking concrete pavement
and extensive green roofs are completely (i.e., 100%)
substituted for conventional surfaces, with runoff coefficients
ranging from 0.25 to 0.5.
As a seen in Table 14, if only extensive green roofs are
reduction of approximately 12% for the total Study Site
would be observed. Alternatively, if only sidewalks are
replaced by PICP, a runoff reduction of less than 7% for the
total area would be generated. Finally, if only the parking lots
are completely replaced by PICP, a runoff reduction of
runoff could be achieved.
to
34,246m3
(Table 15).
9.2.6 Scenario 2b: 75% Pervious Coverage of Hard Surface
and extensive green roofs are substituted for 75% of
0.25 to 0.5.
PICP, a runoff reduction of 5% for the total area would be
generated. Finally, if only the parking lots are partially
replaced by PICP, a runoff reduction of approximately 33%
all hard surfaces, a 47% reduction runoff could be achieved.
to
36,999m3
(Table 15).
9.2.7 Scenario 2c: 50% Pervious Coverage of Hard Surfaces
0.25 to 0.5.
PICP, a runoff reduction of more than 3% for the total area
would be generated. Finally, if only the parking lots are
simply replaced by PICP, a runoff reduction of approximately
22% for the total area would be observed. By substituting
50% of all hard surfaces, a 31% reduction in runoff could be
achieved.
to
39,733m3
(Table 15).

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9.2.8 Scenario 2d: 25% Pervious Coverage of Hard Surfaces
0.25 to 0.5.
PICP, a runoff reduction of nearly 2% for the total area would
be generated. Finally, if only the parking lots are partially
replaced by PICP, a runoff reduction of approximately 11%
all hard surfaces, a 16% reduction in runoff could be
achieved.
to
42,486m3
(Table 15).
9.3 Net-Water Savings Analysis Summary
The WPC Study Site is an ideal location for
substituting conventional surfaces with permeable
surfaces, providing a suitable example for other
similar areas within the City of London
Each scenario shows a general reduction in surface
imperviousness and particularly runoff quantity,
ranging from a minimum of 1% to a maximum of 62%
depending on the configuration and implementation
of each surface
Using an ideally installed permeable pavement and
extensive green roof system may allow the WPC
Study Site to reduce the size of the SWM facility to
approximately 34,000m3

Table 14: Comparison of runoff reductions for conventional and permeable surfaces at the WPC: PICP and green roofs
Full calculations for Table 14 can be found in Appendix B
Table 15: SWM facility volume reduction resulting from pervious surface coverage at the WPC: PICP and green roofs
Runoff Reductions Resulting from Pervious Surface Coverage at the WPC: PICP and Green Roofs
Percent Runoff Reduction for:
SURFACE 100% Pervious Coverage 75% Pervious Coverage 50% Pervious Coverage 25% Pervious Coverage
PICP Parking Lots 43.7 32.7 21.8 10.9
PICP Sidewalks 6.7 5.0 3.4 1.7
Green Roof 11.9 9.0 6.0 3.0
Total Runoff Reduction 62.3 46.7 31.2 15.6
Stormwater Facility Volume Reduction Resulting from Pervious Surface Coverage at the WPC: PICP and Green Roofs
Reduction in Stormwater Facility Volume for:
SURFACE
100% Pervious
Coverage (m3
)
(m3
)
(m3
)
(m3
)
PICP Parking Lots 7,710 5,769 3,846 1,923
PICP Sidewalks 1,182 882 600 300
Green Roof 2,100 1,588 1,059 529
Total Reduction 10,992 8,239 5,505 2,752

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10. Financial Analysis
10.1 Introduction
A financial analysis of each product typology was conducted
using both the Net Present Value (NPV) and Equivalent
Annual Cost (EAC). The following formulas were used to
calculate NPV and EAC:
Where:
∑ represents the sum of each discounted cash flow
over the lifespan of the individual product
i = the annual interest rate, calculated at 5%
t = the time of the cash flow
R = the net cash flow at time t
Where:
i = the annual interest rate, calculated at 5%
t = the lifespan of the individual product
Capital costs, operation and maintenance costs, and the
product lifespan were calculated using information provided
by contractors and distributors and various sources of
literature as described in the “Product Analysis” section of
this Report. Where applicable, an average of the costs of
each product within a specific typology was used to
determine the capital cost. The average capital costs of
each product reflect the entire cumulative cost of installation.
The interest rate of 5% was provided by the Clients as a
standard measurement used by the City of London.
10.2 Net Present Value & Equivalent Annual Cost
10.2.1 Net Present Value and Prorated Net Present Value
For all capital-intensive municipal infrastructure projects, it is
assumed that the total cost of a project will be paid over a
period of time. Net Present Value calculations were
conducted in order to compare the current dollar value of
each surface type, taking inflation and potential savings from
the reduction of stormwater management facilities into
account. In essence, the lower the present dollar value per
metre squared of a product, the more financially feasible it is.
For the purposes of this Study, a “prorated” Net Present
Value was also calculated in order to compare the current
dollar value of each product over the lifespan of the longest-
lasting product of the same general typology (i.e., ground
cover vs. roof). Although this calculation provides a good
visual comparison between products over a common
lifespan, it is important to note that none of the products can
be extended beyond their lifetime without doubling their
lifetime. For example, the lifespan of conventional asphalt
(25 years) cannot be extended by only 5 years in order to

give it an equal lifespan of conventional or porous concrete
(30 years). Rather, it must be renewed for an additional 25
years. For this reason, the Equivalent Annual Cost
calculation was used in order to establish a more accurate
comparison of the dollar value per square metre of each
product, as discussed below.
10.3 Equivalent Annual Cost
EAC reflects the cost per year of owning and operating an
asset over its entire lifespan. The calculation uses the Net
Present Value of an asset as well as an Annuity Value that is
unique to each asset, or product, based on its lifespan.
Since each product in this Report has a different life
expectancy, this calculation is an excellent way to compare
and evaluate the cost of each product on an annual basis,
given that the products will likely be renewed indefinitely
after each lifecycle, and the City will continue to pay for them
year after year.
10.4 Product Comparisons
Net Present Value and Equivalent Annual Cost per square
metre of each product are shown in Table 16, below. For
these initial calculations, no value has been given to the
potential SWM pond reduction savings that may occur when
implementing permeable surfaces. This benefit will be
incorporated into the scenario calculations conducted for the
WPC in the following subsection.
With respect to ground surface coverage, a few key findings
from the financial analysis are present:
First, porous concrete and permeable asphalt had a
better EAC and NPV than conventional concrete.
Therefore, irrespective of their stormwater retention
capacity, long-term savings could exist even if only
sidewalks were constructed with one of these
products.
Conventional asphalt and permeable asphalt had
similar costs, with permeable asphalt amounting to
only $0.97/m2
more than asphalt. As previously
mentioned, this number does not take into
consideration the potential cost savings from
stormwater reduction, and therefore could be more
financially feasible for new developments than
traditional pavement.
Although the capital cost of PICP is comparable to
both conventional and permeable asphalt, the EAC
and NPV are much higher for this product as a result
of its increased maintenance costs. Therefore, it is
likely that PICP would not be financially feasible for
the City of London.
Without considering potential savings from reduced
stormwater infrastructure, the three most financially
feasible options for ground coverage are: 1.
Conventional asphalt; 2. Permeable asphalt, and; 3.
Porous concrete.
With respect to roofs, four surface types were analyzed:
Low-grade conventional roofs, high-grade conventional
roofs, extensive green roofs and intensive green roofs.
Based on information gathered from industry professionals,
low-grade roofs were determined to be roofs built for
approximately $75/m2
that had a lifespan of approximately

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seven years. High-grade roofs were determined to be those
roofs that were built using the most recent knowledge and
highest quality installation methods. These roofs cost
approximately $124/m2
yet last for an average of 20 years.
In this analysis, the capital cost of the high-grade roof has
been added to the cost of both extensive and intensive
green roofs to reflect the added structural cost needed to
support a green roof system.
The first two years of operation and maintenance (O&M) for
extensive green roofs are more intensive and therefore have
an increased cost compared to subsequent years. However,
this increased cost is included in the capital cost of extensive
green roofs. Therefore, the operation and maintenance
costs for extensive green roofs are the same as conventional
roofs after the first two years because they require the same
amount of attention.
The following results were calculated for roof surfaces:
The high-grade conventional roof is the most
financially feasible option of all roof types, not
accounting for potential stormwater cost savings.
The EAC of extensive green roofs is $1.76/m2
more
than the high-grade conventional roof. This is mainly
due to their extended lifespan of 40 years. However,
it should be noted that the lifespan for green roofs in
Southern Ontario is a high-level estimation and may
be inexact, given that green roofs are a relatively new
product in this region.
Intensive green roofs are the most expensive roof
surface and as such are likely not a financially
feasible option for the City of London.

Table 16: Financial comparisons of different surfaces
10.5 Wonderland Power Centre
The Surface Analysis of the Wonderland Power Centre can
be used in conjunction with the calculated NPV and EAC for
each surface type in order to determine the cost of
constructing a development similar to the WPC. A key part
of this analysis is the financial benefit gained from reducing
the size of the stormwater management facility. For the
purposes of this Report, a direct relationship between the
reduction in stormwater runoff and the reduction in the cost
of the stormwater facility has been assumed. However, a
more detailed study would show that real costs are not
linear.
Reduced capital costs and reduced annual maintenance
costs of the WPC SWM facility have been included in the
NPV calculations of each surface type.
Financial Comparisons of Different Surfaces
Surface Material
Capital Cost
($/m2
)
O&M
($/m2
/year)
Life Span
(years)
Net Present
Value ($/m2
)
EAC
($/m2
)
Ground Materials
Conventional Asphalt 95.00 0.09 25 54.77 3.89
Conventional Concrete 215.00 0.07 30 111.27 7.24
Permeable Asphalt 95.00 0.11 20 60.54 4.86
Porous Concrete 170.00 0.07 30 88.21 5.74
PICP 96.77 10.76 25 206.21 14.63
Roofs
Conventional Roof (Low Grade) 75.35 1.35 7 70.10 12.11
Conventional Roof (High Grade) 123.79 1.35 20 93.96 7.54
Extensive Green Roof 317.82 1.35 40 159.50 9.30
Intensive Green Roof 295.95 8.07 40 265.43 15.47

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The adjusted NPV, EAC, and a prorated NPV for each
product are calculated for three general applications (parking
lots, sidewalks and roofs). The results are presented in
Table 17, below. For each application, it is assumed that
each surface material covers 100% of its applicable area of
the WPC Study Site, as outlined in the 3.6 Surface Analysis
above.
With respect to parking lot materials, the following results
were found:
Conventional asphalt and permeable asphalt have
the lowest NPV and EAC of all parking lot materials.
The NPV of permeable asphalt is lower than
conventional asphalt because of the potential SWM
facility savings it provides. However, due to the
shorter lifespan of permeable asphalt, the EAC for
this product is slightly more than the EAC for
conventional asphalt.
Porous concrete and PICP result in significant cost
increases compared to either conventional or
permeable asphalt. It is therefore not likely that
either option would be financially feasible to use for
large parking surfaces.
All permeable parking lot surfaces provide significant
capital SWM facility savings when compared to
conventional asphalt. As such, the City may benefit
from further exploring the feasibility of implementing
these surfaces in parking lots on a limited basis.
With respect to sidewalk materials, the following results were
found:
Both the NPV and EAC for porous concrete are less
than those of conventional concrete when used for
sidewalks, representing a significant cost savings.
PICP has the highest financial savings resulting from
reduced stormwater capital and maintenance costs,
yet has the highest NPV and EAC of any sidewalk
material. Compared to conventional concrete, the
EAC of PICP is approximately $42,000 more.
With respect to roofing materials, the following results were
found:
High-grade conventional roofs have the lowest EAC
of any roof material.
Extensive green roofs resulted in significant SWM
facility savings, but had nearly twice the EAC of high-
grade conventional roofs. As such, it is unlikely that
developers will construct green roofs unless there are
incentives or regulations established by the City.

Table 17: Financial comparisons of different surface applications at the WPC
10.6 Additional Economic Benefits
10.6.1 Monetary Value of Environmental Benefits
In order to fully express the benefits of permeable surfaces,
environmental and social benefits may be considered in
terms of their potential monetary value. Similarly, it is
important that the environmental and social disadvantages of
products be taken into consideration by decision-makers. If
advantages or disadvantages of particular products increase
or decrease the costs incurred by stakeholders (e.g.,
developers, municipalities, provincial or federal
governments) over the short or long term, those costs should
be accurately quantified. Efforts to quantify the
environmental and social advantages and disadvantages of
particular products are documented and appear to be an
emerging field of study.
Financial Comparisons of Different Surface Applications at the WPC
Surface Material Application
Area of WPC
(m2
)
Capital SWM
Facility Savings
Net Present
Value
Prorated Net
Present Value EAC
Ground Materials (over 30 years)
Conventional Asphalt Parking Lots 96,161 $0 $8,808,960 $11,386,424 $625,017
Permeable Asphalt Parking Lots 96,161 $321,822 $8,482,263 $11,468,370 $680,639
Porous Concrete Parking Lots 96,161 $321,822 $15,324,022 $15,324,022 $996,850
PICP Parking Lots 96,161 $417,632 $22,017,796 $25,662,507 $1,562,217
Conventional Concrete Sidewalks 14,812 $0 $3,048,241 $3,048,241 $198,292
Porous Concrete Sidewalks 14,812 $49,133 $2,360,879 $2,360,879 $153,579
PICP Sidewalks 14,812 $63,873 $3,391,958 $3,953,370 $240,668
Roofs (over 40 years)
Conventional Roof (Low Grade) Roofs 42,744 $0 $3,346,228 $10,060,504 $578,294
Conventional Roof (High Grade) Roofs 42,744 $0 $5,703,279 $7,852,785 $457,646
Extensive Green Roof Roofs 42,744 $113,006 $13,750,459 $13,750,459 $801,351
Intensive Green Roof Roofs 42,744 $113,006 $17,515,574 $17,515,574 $1,020,775

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Banting et al. (2005) conducted an extensive literature
review to determine the environmental benefits of green
roofs. The study mainly focuses on the quantification of
benefits and potential monetary savings. In their study, the
benefits from stormwater flow reduction including the impact
on combined sewer overflow, improvement in air quality,
reduction in direct energy use, and reduction in UHI effect
were evaluated. These factors were considered the most
quantifiable benefits of green roofs in terms of monetary
value. The authors also indicated benefits such as the
aesthetic improvement of urban landscape, an increase in
property values, benefits resulting from the use of green
roofs as amenity spaces, the use of green roofs for food
production, and increased biodiversity. Table 18 provides a
synopsis of a portion of their findings.
According to Clark et al. (2008), if the value of improved air
quality resulting from green roofs is quantitatively
considered, improved air quality results in a mean NPV for
the green roof that is approximately 25% to 40% less than
the mean NPV of a conventional roof. This valuation
scenario reveals that over 40 years, green roofs cost less
than conventional roofs (Clark et al., 2008).
Table 18: Financial benefits of green roofs in Toronto, Ontario assuming 50 Million m
2
of available roof space
Financial Benefits of Green Roofs
Category of
Benefit
Initial Cost
Savings ($)
Initial Cost Savings
($/m2
)
Annual Cost
Savings ($)
Annual Cost Savings
($/m2
)
Stormwater 118,000,000 2.36
Combined Sewer
Overflow
46,600,000 0.93 750,000 0.02
Air Quality 2,500,000 0.05
Building Energy 68,700,000 1.37 21,560,000 0.43
Urban Heat Island 79,800,000 1.60 12,320,000 0.25
Total 313,100,000 6.26 37,130,000 0.74
Source: Banting, 2005

11. Conclusions
11.1 Durability
Research conducted for each permeable surface analyzed in
this Report showed that the longevity of permeable products
is comparable to, if not greater than, conventional surface
materials.
Porous concrete and conventional concrete have
equivalent lifespans of 30 years each; longer than
any other pavement material analyzed in this Report.
Although there may be some unforeseen costs
associated with the maintenance of porous concrete
over time, this product is still highly comparable to
conventional concrete and may be ideal for smaller
applications throughout the City, such as sidewalks.
Although permeable asphalt does not have as long of
a lifespan as conventional asphalt, it could be applied
in a limited capacity, such as commercial or
recreational areas that experience very low levels of
vehicular traffic. The City has a history of
maintenance issues with PICP, and therefore they
should not be used to cover large surface areas.
However, if used in conjunction with other permeable
or conventional surfaces (such as concrete), on a
limited basis, PICP may be an adequate material for
stormwater mitigation.
With proper maintenance, extensive green roofs can
double the lifespan of conventional roofs while
providing valuable environmental services. However,
for commercial developments such as the WPC, this
maintenance is dependent on building managers as
opposed to the City. Agreements may need to be
established between the City and private
stakeholders in order to provide incentives for
adequate property maintenance.
Based on the findings pertaining to the lifespan and
maintenance requirements of the products analyzed in this
report, permeable surfaces may be considered as a viable
option for new commercial developments within the City of
London.
11.2 Net water Savings
Across the board, permeable surfaces result in a general net
water savings by reducing the amount of runoff that may
otherwise need to be collected by stormwater management
facilities.
PICP had the greatest net water savings of any
product when used for either parking lots or
sidewalks. Even at minimal coverage (25%), PICP
has the potential to reduce overall runoff by up to
11% when used in large parking lots (approximately
100,000m2
). As such, the City may want to explore
the use of PICP in low-traffic areas on a limited
basis.
Porous concrete provided significant net water
savings (approximately 5%) if used for all sidewalk
surfaces in a development such as the WPC. If
used for municipal applications, porous concrete

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may be an excellent alternative to conventional
concrete sidewalks.
Extensive green roofs also provided significant
reductions in stormwater runoff, even if
implemented on a limited basis. For example, roofs
which are equipped with 50% extensive green roof
coverage can reduce stormwater runoff by 6% for a
development such as the WPC.
Based on these findings, the City of London may benefit
from exploring the options for implementing permeable
surfaces on both public and private properties. In the case
of private developments, agreements would likely have to be
made with developers to establish a mutual benefit for the
implementation of permeable surfaces.
Although all permeable surfaces provide for potential cost
savings due to reduced stormwater management
infrastructure, most permeable surfaces require higher
overall capital expenditures and annual costs than their
conventional counterparts. However, this is not without
exception.
When used for sidewalk applications, it was
determined that porous concrete was more cost
effective than conventional concrete. As such, the
City may want to further examine the feasibility of
using porous concrete for future sidewalk
construction projects. Porous concrete was not
financially feasible for parking lot surfaces.
Although it is not traditionally used as a sidewalk
material, permeable asphalt also proved to be a more
cost effective alternative to conventional concrete
sidewalks.
The NPV and EAC of permeable asphalt were very
similar to conventional asphalt when used for parking
lot surfaces. Given the stormwater retention
capabilities of permeable asphalt, the City may want
to further explore the benefits of using this product
despite its increase in cost.
When used for parking lots or sidewalks, PICP
represented a significant cost increase compared to
any other surface material. As such, it is not likely
financially feasible to use this product for large
parking lot or sidewalk applications. However, the
City may want to explore the limited use of PICP in
conjunction with more financially feasible surfaces to
take advantage of its high capacity to retain
stormwater.
With respect to roofing systems, both intensive and
extensive green roofs were not found to be financially
feasible given their increased capital and annual
costs. Extensive roofs may be more financially
feasible if implemented on a limited basis, such as
50% coverage or less. However, because the
developer must incur the cost of constructing a green
roof, and the property manager must incur the cost of
maintaining it, the City would likely have to look into
establishing regulation(s) or an incentive program(s)

to encourage the use of extensive green roofs in
London.
If properly quantified, the additional financial benefits
gained indirectly from permeable surfaces may
provide further justification for the development of
public policy or design standards which encourage
and/or regulate the use of permeable surfaces.
The financial analysis of this Report showed that in most
cases, permeable surfaces are more expensive than their
conventional counterparts. Therefore, the City might only
consider implementing them on a limited basis in order to
take advantage of their environmental benefits. However,
porous concrete sidewalks are a financially viable option that
could be implemented on a larger scale.
11.4 Summary
After considering all three analyses conducted in this Report,
the City may realize tangible benefits from pursuing
permeable surface stormwater management, particularly
through the use of porous concrete for sidewalk surfaces.
Table 19 below, provides a summary of the findings of this
Report. Each product is evaluated against its conventional
counterpart for each application. The evaluations have been
divided into three parts: Cost, durability and water savings.
Where there is a green check (√), the permeable product
performed better than its conventional counterpart. Where
there is a red x (X), the permeable product did not perform
as well as its conventional counterpart.

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Table 19: Overall product comparisons
Comparisons between Permeable Products and their Conventional Counterparts
Application Evaluation Product
Porous Concrete PICP Permeable Asphalt Extensive Green Roof
Sidewalks
Cost √ X √ -
Durability √ X X -
Water Savings √ √ √ -
Parking Lots
Cost X X X -
Durability √ X X -
Water Savings √ √ √ -
Roofs
Cost - - - X
Durability - - - √
Water Savings - - - √

12. Recommendations
12.1 Durability
Site-specific research should be conducted to determine any
additional maintenance fees associated with the
implementation of permeable surfaces (particularly porous
concrete) in future developments within the City of London.
12.2 Net Water Savings
Given that all permeable surfaces provide a significant level
of net water savings, further research should be conducted
regarding the most suitable way to encourage and/or
regulate the use of permeable surfaces in private
developments.
Site-specific studies for future developments with planned
stormwater facilities should be conducted in order to
accurately quantify the savings resulting from reduced
infrastructure costs.
Further research should be conducted with respect to the
feasibility of using porous concrete instead of conventional
concrete for sidewalks.
Further research should be conducted pertaining to the
financial feasibility of using permeable asphalt, porous
concrete and/or PICP on a limited scale in parking lots in
order to take advantage of their environmental benefits.
12.4 Additional Recommendations
Further research should be conducted regarding the most
suitable way to encourage and/or regulate the use of
permeable surfaces in private developments. Part of this
research should include evaluating the permeable surface
implementation strategies adopted by other municipalities in
Southern Ontario.
A survey of the public‟s perception of permeable products
may also help support the integration of these products into
public policy and/or development standards.

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References
AECOM. (2009). Storm drainage/SWM servicing development charges update 2008: DC Study Final Executive Summary.
Prepared for the City of London.
Asaeda, T. & Ca, V.T. (2000). Characteristics of permeable pavement during hot summer weather and impact on the thermal
environment. Building and Environment, 35, 363-375.
Backstrom, M. & Bergstrom, A. (2000). Draining function of porous asphalt during snowmelt and temporary freezing. Canadian
Journal of Civil Engineering, 27, 594-598.
Backstrom, M. & Viklander, M. (2000). Integrated stormwater management in cold climates. Journal of Environmental Science
and Health, Part A, 35(8), 1237-1249.
Balades, J. D., Legret, M., & Madiec, H. (1995). Permeable pavements: Pollution management tools. Water Science and
Technology, 32(1), 49-56.
Ball, T. (2008). Urban heat island effect. Friends of Science, 1-8. Retrieved from http://www.friendsofscience.org/assets/
documents/ FoS_Urban%20Heat%20Island.
Banting, D., Doshi, H., Li, J., Missios, P., Au, A., Currie, B.A., & Verrati, M. (2005). Report on the Environmental Benefits and
Costs of Green Roof Technology for the City of Toronto. Prepared for City of Toronto and Ontario Centres of Excellence –
Earth and Environmental Technologies (OCE-ETech) and report. Retrieved from
http://www.toronto.ca/greenroofs/pdf/fullreport103105.pdf
Barnes, K.B., Morgan, J.M., & Roberge, M.C. (2002). Impervious surfaces and the quality of natural and built environments.
Retrieved from http://pages.towson.edu/morgan/ files/Impervious.pdf
Barrow, C.J. (2003). Environmental change and human development. Oxford University Press, New York, NY: +252 pp.
Bean, Z.B., Hunt, W.B., & Bidelspach, D.A. (2007a). Evaluation of four permeable pavement sites in eastern North Carolina for
runoff reduction and water quality impacts. Journal of Irrigation and Drainage Engineering, November/December, 583-
592.

Bean, Z.B., Hunt, W.B., & Bidelspach, D.A. (2007b). Field survey of permeable pavement surface infiltration rates. Journal of
Irrigation and Drainage Engineering, 133 (3), 249-255.
Bean, Z.B., Hunt, W.B., Bidelspach, D.A., & Burak, R.J. (2004). Study on the surface infiltration rate of permeable pavements.
Proceedings of the 2004 World Water and Environmental Resources Congress: Critical Transitions in Water and
Environmental Resources Management, Salt Lake City, Utah, 749-758.
Beecham, S. & Myers, B. (2007). Structural and design aspects of porous and permeable block pavement. Journal of Australian
Ceramic Society, 43(1), 74-81.
Bogemans, J., Nierinck, L., & Stassart, J.M. (1989). Effect of de-icing chloride salts on ion accumulation in Spruce. Plant and Soil,
113, 3-11.
Bouzoubaa, N. & Foo, S. (2005). Use of fly ash and slag in concrete: A best practice guide. Government of Canada Action Plan
2000 on Climate Change. Retrieved from http://www.scm.gc.ca/docs/bestpractices.pdf#page=27
Bouzoubaa, N. & Fournier, B. (2005). Current situation with the production and use of supplementary cementitious materials
(SCMs) in concrete construction in Canada. Canadian Journal of Civil Engineering, 32(1), 129-143.
Boving, T.B, Stolt, M.H., Augenstern, J., & Brosnan, B. (2008). Potential for localized groundwater contamination in a porous
pavement parking lot setting in Rhode Island. Environmental Geology, 55, 571-582.
Brattebo, B.O. & Booth, D.B. (2003). Long-term stormwater quantity and quality performance of permeable pavement systems.
Water Research, 37, 4369-4376.
Brown, K. (2008). Permeable paving. Toronto Regional Conservation Authority with Credit Valley Conservation. Retrieved from
http://www.creditvalleyca.ca/ sustainability/lid/designtool/ fact_sheets/TRCA_LID_10-PermeablePaving121708.pdf
CaGBC. (2004). LEED Green Building Rating System for New Construction and Major Renovations (LEED – Canada NC Version
1.0). Canadian Green Building Council, Ottawa, Ontario, December 2004.
City of London. (2010). Understanding growth in London. Retrieved from
http://www.london.ca/d.aspx?s=/About_London/londongrowth.htm
City of London. (2006). Schedule A to the City of London Official Plan – Land Use Map No. 7. City of London Official Plan.

JOVIAN DESIGN
Page | 66
City of Toronto. (2010). Green roofs. Living in Toronto. Retrieved from http://www.toronto.ca/greenroofs/overview.htm
Clark, C., Adriaens, P., & Talbot, F. B. (2008). Green roof valuation: A probabilistic economic analysis of environmental benefits.
Environmental Science & Technology, 42(6), 2155-2161.
Committee E-701 Materials for Concrete Construction. (2001).Cementitious materials for concrete. ACI Education Bulletin, E3-1-
E3-25. Retrieved from http://www.concrete.org/general/fE3-01.pdf
Cornell University. (2007). Precipitation. Department of Crop and Soil Sciences. Retrieved from
http://www.css.cornell.edu/faculty/hmv1/watrshed/Return.htm
Daley, M.L., Potter, J.D., & McDowell, W.H. (2009). Salinization of urbanizing New Hampshire streams and groundwater: Effects
of road salt and hydrologic variability. Journal of the North American Benthological Society, 28(4), 929-940.
Decaluwe, D. (2010). Personal interview. Stone in Style. 26 February 2010.
DeMarco, F. (2010). Personal interview. TCG Asphalt and Construction. 8 March 2010.
Development Engineering (London) Limited. (2005). Final stormwater management report for the Bradley Avenue stormwater
management facility. City of London, County of Middlesex. Prepared for Southside Construction, + 37pp.
Dingman, S.L. (2002). Physical hydrology (Second Edition). Pearson Education Canada, Ltd., Toronto, Ontario. + 646 pp.
Elite Surfacing. (2010). Driveways. Retrieved from http://elitesurfacing.com/Driveways/tabid/835/language/en-US/Default.aspx
Environment Canada. (2010). Canadian climate normals 1971-2000. National Climate Data and Information Archive. Retrieved
from http://climate.weatheroffice.gc.ca/climate_normals/ results_e.html?Province
=ALL&StationName=London&SearchType=BeginsWith&LocateBy=Province&Proximity=25&ProximityFrom=City&Station
Number=&IDType=MSC&CityName=&ParkName=&LatitudeDegrees=&LatitudeMinutes=&Longi
Environment Canada and Health Canada. (2001). Priority substances list assessment report for road salts. Minister of Public
Works and Government Services, Ottawa, Ontario.
Environmental Services Water Quality Division. (2009). Stormwater Glossary. Wake County, North Carolina. Retrieved from
http://www.wakegov.com/water/stormwater/taskforce/links/ glossary.htm

Fancher, S. & Townsen, S. (2003). Sustainable infrastructure: Alternative paving materials subcommittee report. City of Portland,
Bureau of Environmental Services, October 2003, 1-20.
Feig, D.I. & Paya, R. (1998). Road salt impacts on drinking water. American Heart Association Journal: 99-112.
Fischel, M. (2001). Evaluation of selected de-icers based on a review of the literature. Prepared by the SeaCrest Group,
Colorado Department of Transportation. Denver, Colorado: +117 pp.
Fisher Tracks. (2010). Polyurethane track surfaces. Retrieved from http://www.fishertracks.com/polyurethane_tracks.html
Freemantle, M. (1999). Asphalt. Chemical & Engineering News, 77(47), 81.
Gilbert, J.K. & Clausen, J.C. (2006). Stormwater runoff quality and quantity from asphalt, paver, and crushed stone driveways in
Connecticut. Water Research, 40, 826-832.
Golden, J. & Kaloush, K. (2005). A hot night in the Big City: How to mitigate the urban heat island. Public Works Online,
December. Retrieved from http://www.pwmag.com/industry-news.asp?sectionID=770&articleID=268116
Google Maps. (2010). London Ontario. Retrieved from http://maps.google.com/maps
Govers, K. Personal interview. (2010). LiveRoof Ontario. 15 March 2010.
Gunderson, J. (2008). Pervious pavements: new findings about their functionality and performance in cold climates. Stormwater,
September, 1-3. Retrieved from http://www.stormh2o.com/september-2008/pervious-asphalt-concrete.aspx
Guntner, M. & Wilke, B.M. (1983). Effects of de-icing salt on soil enzyme activity. Water, Air, and Soil Pollution, 20, 211-220.
Hirshorn, S. (2010). Paving with drainage. Landscape Trades, 32(1), 8-10.
Howard, K.W.F. & Beck, P.J. (1993). Hydrogeochemical implications of groundwater contamination by road de-icing chemicals.
Journal of Contaminant Hydrology, 12, 245–268.
HydroCAD. (2009). Understanding Exfiltration. HydroCAD Stormwater modelling. Retrieved from
http://www.hydrocad.net/exfilt.htm

JOVIAN DESIGN
Page | 68
Interlocking Concrete Pavement Institute (ICPI). (2008). Permeable interlocking concrete pavement. Washington, DC: ICPI.
Retrieved from http://www.romanstone.com/pdfs/PICPcomparisonGuide.pdf
Interlocking Concrete Pavement Institute (ICPI). (2007). Achieving LEED credits with segmental concrete pavement. Tech Spec,
16, 1-24. Burlington, ON.
Kohler, M., Schmidt, M., Grimme, F.W., Laar, M., de Assuncao Paiva, V.C., & Tavares, S. (2002). Green roofs in temperate
climates and in the hot-humid tropics – far beyond the aesthetics. Environmental Management and Health, 13(4), 382-
391.
Kosareo, L. & Ries, R. (2007). Comparative environmental life cycle assessment of green roofs. Building and Environment, 42(7),
2606-2613.
Landers, J. (2008). Chicago uses permeable materials to make alleys „green‟. Civil Engineering, January, 26-28.
Legret, M. & Colandini, V. (1999). Efffects of a porous pavement with reservoir structure on runoff water: Water quality and fate of
heavy metals. Water Science and Technology, 39, 111-117.
Li, Z., Li, F., & Li, J.S.L. (1998). Properties of concrete incorporating rubber tire particles. Magazine of Concrete Research, 50(4),
297-304.
Liu, K. & Baskaran, B. (2003). Thermal performance of green roofs through field evaluation. Institute for Research in
Construction, 1-10.
LiveRoof. (2010). Prevegatated invisible modular green roof system. www.liveroof.com
Lui, G., Widger, R.A., & Jin, Y.C. (2006). Trend analysis of road salt impacts on groundwater salinity at a long-term monitoring
site. Annual Conference of the Transportation Association of Canada, Charlottetown, Prince Edward Island: pp. 1-13.
Malhotra, V.M., & Mehta, P.K. (1996). Pozzolanic and cementitious materials. Advances in concrete technology. Vol. 1. Gordon
and Breach Science Publishers, Amsterdam, The Netherlands.
Mallay, C. (2010). Personal interview. Duo Building Ltd. 1 March 2010.
Mentens, J., Raes, D., & Hermy, M. (2005). Green roofs as a tool for solving the rainwater runoff problems in the urbanized 21st
century? Landscape and Urban Planning, 77, 217-226.

Metropolitan Area Planning Council. (2010). Fact sheet: Permeable paving. Massachusetts Low Impact Development Toolkit.
Retrieved from http://www.mapc.org/sites/default/files/LID_Fact_Sheet_-_Permeable_Paving.pdf
Mutual Materials. (2010). Permeable pavers. Retrieved from
http://www.mutualmaterials.ca/Homeowner_product_permeable_pavers_SF_rima.php
National Asphalt Pavement Association (NAPA). (2008). Asphalt pavements and the LEED green building system. Lanham, MD.
National Ready Mixed Concrete Association. (2008). Concrete CO2 fact sheet. National Ready Mixed Concrete Association.
Retrieved from http://www.nrmca.org/GreenConcrete/CONCRETE%20CO2%20FACT%20SHEET%20JUNE%202008.pdf
National Ready Mixed Concrete Association. (2010). Pervious concrete: Engineering properties. National Ready Mixed Concrete
Association. Silver Spring, MD. Retrieved from http://www.perviouspavement.org/engineering%20properties.htm
Natural Resources Canada. (2003). The Atlas of Canada - Annual Precipitation. Retrieved from
http://atlas.nrcan.gc.ca/auth/english/maps/archives/3rdedition/ environment/climate/025
Ngan, G. (2004). Green roof policies: Tools for encouraging sustainable design. +49 pp. Retrieved from www.gnla.ca.
Oke, T.R. (2006). Boundary layer climates (2nd
edition). Methuen & Co. Ltd. +338 pp.
Park, S., & Tia, M. (2003). An experimental study on the water-purification properties of porous concrete. Cement and Concrete
Research, 34(2), 177-184.
Pavers By Ideal. (2005). Turfstone Grid Pavers. Pavers By Ideal, Westford, Massachusetts. Retrieved from
http://www.paversbyideal.com/pdf/Turfstone.pdf
Peck, S. & Kuhn, M. (n/d), Design guidelines for green roofs. Canadian Mortgage and Housing Corporation. Retrieved from
http://www.cmhc.ca/en/inpr/bude/himu/coedar/loader.cfm?url=/commonspot/security/getfile.cfm&PageID=70146
Permacon. (2010). Subterra pavers. Retrieved from http://www.permacon.ca/products.html?product_id=491&z=Subterra
Pratt, C.J. (1999). Use of permeable, reservoir pavement constructions for stormwater treatment and storage for re-use. Water
Science and Technology, 39(5), 145-151.
Presto. (2010). GeoSystems. Retrieved from http://www.prestogeo.com/geoblock

JOVIAN DESIGN
Page | 70
Prodanovic, P. & Simonovic, S.P. (2007). Development of rainfall intensity duration frequency curves for the City of London under
the changing climate. Water Resources Research Report, no. 054. Department of Civil and Environmental Engineering,
University of Western Ontario, London, Ontario. +50 pp.
Rajani, B., & Zhan, C. (1997). Performance of concrete sidewalks: Field studies. Canadian Journal of Civil Engineering, 24, 303-
312.
Ramakrishna, D.M., & Viraraghavan, T. (2005). Environmental impact of chemical de-icers – A review. Water, Air, and Pollution,
166, 49-63.
Robinson, D., Terella, M., & Rosenfeld, B. (2009). Stormwater Inventory Masterplan. Prepared for Pasco County, Florida.
Retrieved from http://proceedings.esri.com/library/userconf/serug09/papers/
pasco_county_stormwater_inventory_master_plan.pdf
Roseen, R.M. & Ballestero, T.P. (2008). Porous asphalt pavements for stormwater management in cold climates. Hot Mix Asphalt
Technology, May/June 2008.
Roseen, R.M., Ballestero, T.P., Houle, J.J., Avellaneda, P., Briggs, J, Fowler, G., et al. (2009). Seasonal performance variations
for stormwater management systems in cold climate conditions. Journal of Environmental Engineering, 135(3), 128-137.
Rowlett, R. (2002). How many? A dictionary of units of measurement. The university of North Carolina of Chapel Hill. Retrieved
from http://www.unc.edu/~rowlett/units/dictR.html
Rushton, B. (2001). Low-impact parking lot design reduces runoff and pollutant loads. Journal of Water Resources Planning and
Management, 127(3), 172-179.
Sansalone, J., Kuang, X., & Ranieri, V. (2008). Permeable pavement as a hydraulic and filtration interface for urban drainage.
Journal of Irrigation and Drainage Engineering,134(5), 666-674.
Shuster, W.D., Bonta, J., Thurston, H., Warnemuende, E., & Smith, D.R. (2005). Impacts of impervious surface on watershed
hydrology: A review. Urban Water Journal, 2(4), 263-275.
Smith, D. R. (2006). Permeable interlocking concrete pavements: Selection, design, construction, maintenance. Burlington,
Ontario: Interlocking Concrete Pavement Institute.

Smith, T. (2006). Helping build a sustainable future by constructing roadways with Portland cement concrete pavement. Cement
Association of Canada. Retrieved from
http://www.tacatc.ca/english/resourcecentre/readingroom/conference/conf2006/docs/s012/tsmith.pdf
Southside Group. (2010). Wonderland Power Centre – London, Ontario. Retrieved from
http://www.southsidegroup.ca/commercial/d/cc_wonderland_pc.html
Statistics Canada. (2006). Projected population and dwelling count (municipalities) according to a medium growth scenario.
Statistics Canada, 2006 Census.
Stenmark, C. (1995). An alternative road construction for stormwater management in cold climates. Water Science and
Technology, 32(1), 79-84.
SWITCH Urban Water. (2007). Briefing notes: Sustainable stormwater management. SWITCH Resources. Retrieved from
http://switchurbanwater.lboro.ac.uk/outputs/results.php?pubtype_select=1
Taves, D. (2010). Personal interview. Gardens in the Sky, Flynn Canada. 22 March 2010.
Tennis, P.D., Leming, M.L., & Akers, D.J. (2004). Pervious concrete pavements. Portland Cement Association, Skokie, IL., and
National Ready Mix Concrete Association, Silver Spring, MD. +25 pp
Toronto and Region Conservation Authority (TRCA). (2007). Performance evaluation of permeable pavement and a bioretention
swale Seneca College, King City, Ontario. Toronto, Ontario: TRCA
Tricar Group. (2010). Luxury Apartments – London. Retrieved from http://www.tricar.com/ap_london.html#west.
Troumbulak, S.C. & Frissell, C. (2000). Review of ecological effects of roads on terrestrial and aquatic communities.
Conservation Biology, 14(1), 18-30.
Uni-EcoLocTech. (2008). Uni-Ecoloc. Mutual Materials, Vancouver, Washington.
Unilock. (2009). Directions in Sustainable Design. Hangestone Holdings, Inc., Toronto, ON.
Unilock. (2010). Permeable Products. Retrieved from http://www.unilock.com/products/product.php?prodid=14

JOVIAN DESIGN
Page | 72
United States Environmental Protection Agency (EPA). (2009). Porous Asphalt Pavement. National Pollutant Discharge
Elimination System, September 2009.
United States Environmental Protection Agency (EPA). (1999). Stormwater Technology Fact Sheet: Wet Detention Ponds.
Municipal Technology Branch, September 1999. Retrieved from http://www.epa.gov/owm/mtb/wetdtnpn.pdf
United States Environmental Protection Agency. (2009). Heat Island Effect: Basic Information. Washington DC: EPA.
http://www.epa.gov/heatisland/about/index.htm
University of Florida. (2008). Florida field guide to low impact development. Program for Research Efficient Communities.
Retrieved from http://buildgreen.ufl.edu/Fact_sheet_ Permeable_Surfaces.pdf
University of Florida. (2007). Glossary of water related terms. CSREES Florida Water Quality Program. Retrieved from
http://waterquality.ifas.ufl.edu/Glossary/Glossary .htm#Baseflow
Van Woert, N.D., Rowe, D.B., Andersen, J.A., Rugh, C.L., Fernandez, R.T., & Xiao, L. (2005). Green roof stormwater retention:
Effects of roof surface, slope and media depth. Journal of Environmental Quality, 34, 1036-1044.
Vasiliu, G. (2010). Personal interview. Coco Asphalt Engineering. 5 March 2010.
Veldjesgraaf, B. & Yantzi, R. (2008). Permeable interlocking concrete pavements PICP. Received from Darcy Decaluwe
Vonk, J. (2010). Personal interview. Zinco Canada. 24 February 2010.
Walker, D. (2006). Porous Asphalt Reduces Storm Water Runoff. Asphalt: Online Magazine. Retrieved from
http://www.asphaltmagazine.com/singlenews.asp?item_ ID=1178&comm=0&list _code_int=mag01-int
Werner E. & diPretoro, R.S. (2006). Rise and fall of road salt contamination of water-supply springs. Environmental Geology, 51,
537-543.
Williams, D.D., Williams, N.E., & Cao, Y. (1999). Road salt contamination of groundwater in a major metropolitan area and
development of a biological index to monitor its impact. Water Resources, 34(1), 127-138.
Williams, M., Hopkinson, C., Rastetter, E., Vallino, J., & Claessens, L. (2005). Relationships of land use and stream solute
concentration in the Ipswich River Basin, Northeastern Massachusetts. Water, Air, and Soil Pollution, 161, 55-74.

Wendell, O. (2005). Pervious concrete: Frequently asked questions. County Landscape & Design. Retrieved from
http://www.owendell.com/perviouscon.html
Woodward, J. (2010). Personal interview. Grand River Brick & Stone. 2 March 2010.
Worton, M. (2010). Personal interview. Lafarge. 17 March 2010.
ZinCo Canada. (2009). Life on Roofs: Carlisle, ON. www.zinco.ca.

Appendices

Appendix A. 1: Site Context
Schedule A to the City of London Official Plan - Landuse

Low-sloped Roofs Sloped Roofs SWM Pond
Parking Lots & Low-traffic Roadways Sidewalks Medians
Appendix A. 2: Surface Analysis
WPC Surface Analysis Map
Surface Characteristics of the Wonderland Power Centre study area. Modified from the City of London‟s Public Zoning
Map and used for academic purposes: Retrieved February, 2010. Aerial photo taken in April, 2009. Scale = 1 : 3, 030.30

Appendix A. 3: Stormwater Management Inventory
Pinecombe Drainage Catchment Area

Appendix B. 1: Product Analysis
Summary of PICP Products Characteristics:
Summary of Concrete and Asphalt Product Characteristics:
Product Company
Total cost including
installation and sub-base Lifespan Operation and Maintenance Runoff Coefficient
Pervious Concrete Lafarge Canada Inc. $170/m3 30 years Vacuum 1-2 times yearly $0.07/m2/year 0.4
Permeable Asphalt Coco Asphalt Eng. $95/m3 20 years Vacuum 1-2 times yearly $0.11/m2/year 0.4
Conventional Concrete Lafarge Canada Inc. $215/m3 30 years Sweep 1-2 times yearly $0.07/m2/year 0.9
Conventional Asphalt TCG Asphalt & Construction $95/m3 25 years Sweep 1-2 times yearly $0.09/m2/year 0.9
Summary of Green Roof Characteristics:
Green Roof Product Company
Price including
installation Maintenance Durability Runoff Coefficient
Extensive Floradrain FD 25 ZinCo Canada $107.6/m2 $1.35/m2/year 40 years 0.5
Extensive Floradrain FD 25 ZinCo Canada $215.2/m2 $1.35/m2/year 40 years 0.5
Extensive LiveRoof LiveRoof Ontario $150.64/m2 $1.35/m2/year 40 years 0.5
Extensive Duo Building Ltd. Duo Building Ltd. $206.67/m2 $1.35/m2/year 40 years 0.5
Extensive* Soprema Taiga Flynn Canada $161.45/m2 $1.35/m2/year 40 years 0.5
Extensive* Sedum Master Flynn Canada $193.75/m2 $1.35/m2/year 40 years 0.5
Extensive* LiveRoof Flynn Canada $322.90/m2 $1.35/m2/year 40 years 0.5
Intensive* Connon Nursery Flynn Canada $269.10/m2 $8.07/m2/year 40 years 0.3
Intensive Floradrain FD 60 ZinCo Canada $322.8/m2 $8.07/m2/year 40 years 0.3
Product Company Cost of Stone Installation Total of Cost
Cost of
Subbase Durability Operation & Maintenance
Runoff
Coefficient
Eco-Optiloc Unilock $30.34/m2 $37.66/m2 $68.00/m2 $14.7/m2 25 years Vacuum 1-2 times yearly $10.76/m2/year 0.25
Eco-Priora Unilock $74.14/m2 $37.66/m2 $111.8/m2 $14.7/m2 25 years Vacuum 1-2 times yearly $10.76/m2/year 0.25
Subterra Permacon $28.51/m2 $37.66/m2 $66.17/m2 $14.7/m2 25 years Vacuum 1-2 times yearly $10.76/m2/year 0.25

Appendix B. 2: Net Water Savings: Calculations
Appendix B: 100% Pervious Coverage of Hard Surface Using Permeable Asphalt or PC and Green Roofs:
RUNOFF CONVENTIONAL
SURFACE AREA (m2) COEFFICIENT, C DESIGN PERVIOUS COVERAGE IMPERVIOUS AREA,
(IMPERVIOUSNESS) IMPERVIOUS AREA (m2) (100% of Area) PERVIOUS SEGMENTS
Asphalt Pavement 96161 0.9 86545
Concrete Pavement 14812 0.9 13331
Conventional Roof 42744 0.9 38470
Green Roof 0.5 42744 21372
Porous Concrete 0.4 14812 5925
Permeable Asphalt 0.4 96161 38464
Medians and Others 24085 0.2 4817 24085 4817
Total Paved Surface Area 177802 143162 177802 70578
Total Site Area 220785 220785 220785
Site Imperviousness (%) 64.8 32.0
RUNOFF REDUCTION (%) 50.7
SURFACE SURFACE SURFACE
SURFACE AREA (m2) IMPERVIOUS AREA, IMPERVIOUSNESS IMPERVIOUSNESS IMPERVIOUSNESS
PERVIOUS SEGMENTS (GREEN ROOFS) (SIDEWALKS) (PARKING LOTS)
Asphalt Pavement 96161 86545 86545
Concrete Pavement 14812 13331 13331
Conventional Roof 42744 38470 38470
Green Roof 21372 21372
Porous Concrete 5925 5925
Permeable Asphalt 38464 38464
Medians and Others 24085 4817 4817 4817 4817
Total Paved Surface Area 177802 70578 126065 135756 95082
Total Site Area 220785 220785 220785 220785 220785
Site Imperviousness (%) 32.0 57.1 61.5 43.1
RUNOFF REDUCTION (%) 50.7 11.9 5.2 33.6

Appendix B: 75% Pervious Coverage of Hard Surface Using Permeable Asphalt or PC and Green Roofs
RUNOFF CONVENTIONAL
SURFACE AREA (m2) COEFFICIENT, C DESIGN IMPERMEABLE
(IMPERVIOUSNESS) IMPERVIOUS AREA (m2) (25% of Area)
Asphalt Pavement 96161 0.9 86545 21636
Concrete Pavement 14812 0.9 13331 3333
Conventional Roof 42744 0.9 38470 9617
Green Roof 0.5
Porous Concrete 0.4
Permeable Asphalt 0.4
Medians and Others 24085 0.2 4817
Total Paved Surface Area 153717 143162 34586
Total Site Area 220785 220785 220785
Site Imperviousness (%) 64.8
SURFACE SURFACE
SURFACE AREA (m2) IMPERVIOUS AREA, IMPERVIOUSNESS IMPERVIOUSNESS
PERVIOUS SEGMENTS (GREEN ROOFS) (SIDEWALKS)
Permeable Asphalt 50485
Medians and Others 24085 4817 4817 4817
Total Site Area 220785 220785 220785 220785
Site Imperviousness (%) 40.2 59.0 62.3
RUNOFF REDUCTION (%) 38.0 9.0 3.9

Appendix B: 75% Pervious Coverage of Hard Surface Using Permeable Asphalt or PC and Green Roofs continued
PERVIOUS COVERAGE PERVIOUS COVERAGE IMPERVIOUS AREA,
(100% of Area) (75% of Area) PERVIOUS SEGMENTS
42744 16029 25646
14812 4444 7776
96161 28848 50485
4817
153717 49321 88724
220785
40.2
SURFACE
IMPERVIOUSNESS
(PARKING LOTS)
21636
13331
38470
28848
4817
107102
220785
48.5
25.2

RUNOFF CONVENTIONAL
Green Roof 0.5
Porous Concrete 0.4
Total Site Area 220785 220785 220785
SURFACE SURFACE
Total Site Area 220785 220785 220785 220785

42744 10686 29921
14812 2962 9628
96161 19232 62505
4817
153717 32881 106870
220785
48.4
SURFACE
IMPERVIOUSNESS
(PARKING LOTS)
43272
13331
38470
19232
4817
119122
220785
54.0
16.8

RUNOFF CONVENTIONAL
Green Roof 0.5
Porous Concrete 0.4
Total Site Area 220785 220785 220785
SURFACE SURFACE
Total Site Area 220785 220785 220785 220785

42744 5343 34195
14812 1481 11479
96161 9616 74525
4817
153717 16440 125016
220785
56.6
SURFACE
IMPERVIOUSNESS
(PARKING LOTS)
64909
13331
38470
9616
4817
131142
220785
59.4
8.4

Appendix B: 100% Pervious Coverage of Hard Surface Using PICP and Green Roofs
RUNOFF CONVENTIONAL
SURFACE AREA (m2) COEFFICIENT, C DESIGN PERVIOUS COVERAGE IMPERVIOUS AREA,
(IMPERVIOUSNESS) IMPERVIOUS AREA (m2) (100% of Area) PERVIOUS SEGMENTS
Asphalt Pavement 96161 0.9 86545
Concrete Pavement 14812 0.9 13331
Conventional Roof 42744 0.9 38470
Green Roof 0.5 42744 21372
PICP (sidewalk) 0.25 14812 3703
PICP (parking lot) 0.25 96161 24040
Medians and Others 24085 0.2 4817 24085 4817
Total Site Area 220785 220785 220785
Site Imperviousness (%) 64.8 24.4
SURFACE SURFACE SURFACE
SURFACE AREA (m2) IMPERVIOUS AREA, IMPERVIOUSNESS IMPERVIOUSNESS IMPERVIOUSNESS
PERVIOUS SEGMENTS (GREEN ROOFS) (SIDEWALKS) (PARKING LOTS)
PICP (sidewalk) 3703 3703
PICP (parking lot) 24040 24040
Medians and Others 24085 4817 4817 4817 4817
Total Paved Surface Area 177802 53932 126065 133535 80658
Total Site Area 220785 220785 220785 220785 220785
Site Imperviousness (%) 24.4 57.1 60.5 36.5
RUNOFF REDUCTION (%) 62.3 11.9 6.7 43.7

RUNOFF CONVENTIONAL
Green Roof 0.5
PICP (sidewalk) 0.25
PICP (parking lot) 0.25
Total Site Area 220785 220785 220785
SURFACE SURFACE
PICP (parking lot) 39666
Total Site Area 220785 220785 220785 220785

Appendix B: 75% Pervious Coverage of Hard Surface Using PICP and Green Roofs continued
42744 16029 25646
14812 2777 6110
96161 18030 39666
4817
153717 36836 76240
220785
34.5
SURFACE
IMPERVIOUSNESS
(PARKING LOTS)
21636
13331
38470
18030
4817
96284
220785
43.6
32.7

RUNOFF CONVENTIONAL
Green Roof 0.5
Total Site Area 220785 220785 220785
SURFACE SURFACE
Total Site Area 220785 220785 220785 220785

42744 10686 29921
14812 1852 8517
96161 12020 55293
4817
153717 24558 98547
220785
44.6
SURFACE
IMPERVIOUSNESS
(PARKING LOTS)
43272
13331
38470
12020
4817
111910
220785
50.7
21.8

RUNOFF CONVENTIONAL
Green Roof 0.5
Total Site Area 220785 220785 220785
SURFACE SURFACE
Total Site Area 220785 220785 220785 220785

42744 5343 34195
14812 926 10924
96161 6010 70919
4817
153717 12279 120855
220785
54.7
SURFACE
IMPERVIOUSNESS
(PARKING LOTS)
64909
13331
38470
6010
4817
127536
220785
57.8
10.9

Appendix B. 3: Financial Analysis: Calculations
ROOFS
Conventional Roof 1 75.35$ all roof surfaces 42,744 3,220,649$ -$
Conventional Roof 2 123.79$ all roof surfaces 42,744 5,291,067$ -$
Extensive Green Roof 317.82$ all roof surfaces 42,744 13,584,685$ 113,006$
Intensive Green Roof 295.95$ all roof surfaces 42,744 12,650,087$ 113,006$
PARKING LOTS
Conventional Asphalt 95.00$ parking lot/roadways 96,161 9,135,295$ -$
PICP 96.77$ parking lot/roadways 96,161 9,305,885$ 417,632$
Porous Concrete 170.00$ parking lot/roadways 96,161 16,347,370$ 321,822$
Permeable Asphalt 95.00$ parking lot/roadways 96,161 9,135,295$ 321,822$
SIDEWALKS
Conventional Concrete 215.00$ sidewalks 14,812 3,184,580$ -$
PICP 96.77$ sidewalks 14,812 1,433,416$ 63,873$
Porous Concrete 170.00$ sidewalks 14,812 2,518,040$ 49,133$
Permeable Asphalt 95.00$ 14,812 1,407,140$ 49,133$
SWMFacility 2,456,660$
***Assuming a linear relationship between cost of SWMfacilities and Net Water Savings
Proposed ApplicationSurface Type Average Cost
Approximate
SWMCapital
Savings***
Cost to cover 100% of
applicable WPC
surface
Area of WPC
(m2
)

Financial Analysis Calculations Continued
40 years
7 5% 57,704$ $3,346,228 $10,060,504 5.786 $578,294
20 5% 57,704$ $5,703,279 $7,852,785 12.462 $457,646
920$ 40 5% 57,704$ $13,750,459 $13,750,459 17.159 $801,351
920$ 40 5% 344,944$ $17,515,574 $17,515,574 17.159 $1,020,775
30 years
-$ 25 5% 8,270$ $8,808,960 $11,386,424 14.094 $625,017
3,400$ 25 5% 1,034,692$ $22,017,796 $25,662,507 14.094 $1,562,217
2,620$ 30 5% 6,892$ $15,324,022 $15,324,022 15.372 $996,850
2,650$ 20 5% 10,337$ $8,482,263 $11,468,370 12.462 $680,639
30 years
30 5% 1,062$ $3,048,241 $3,048,241 15.372 $198,292
520$ 25 5% 159,377$ $3,391,958 $3,953,370 14.094 $240,668
400$ 30 5% 1,062$ $2,360,879 $2,360,879 15.372 $153,579
400$ 20 5% 1,592$ $1,307,063 $1,815,043 12.462 $104,882
80 5% 20,000$
EACNPV
Prorated NPV
over:
A value
Maintenance &
Operational Cost
per Year**
Lifespan
(years)
Interest Rate
(Annual)
Annual SWM
Savings

Sidewalks
Porous Concrete Sidewalks Conventional Concrete Sidewalks PICP Sidewalks Permeable Asphalt Sidewalks
Year Net Cost Year Net Cost Year Net Cost Year
1 2,468,907$ 1 3,184,580$ 1 1,369,543$ 1 1,358,007$
2 662$ 2 1,062$ 2 158,857$ 2 1,192$
3 662$ 3 1,062$ 3 158,857$ 3 1,192$
4 662$ 4 1,062$ 4 158,857$ 4 1,192$
5 662$ 5 1,062$ 5 158,857$ 5 1,192$
6 662$ 6 1,062$ 6 158,857$ 6 1,192$
7 662$ 7 1,062$ 7 158,857$ 7 1,192$
8 662$ 8 1,062$ 8 158,857$ 8 1,192$
9 662$ 9 1,062$ 9 158,857$ 9 1,192$
10 662$ 10 1,062$ 10 158,857$ 10 1,192$
11 662$ 11 1,062$ 11 158,857$ 11 1,192$
12 662$ 12 1,062$ 12 158,857$ 12 1,192$
13 662$ 13 1,062$ 13 158,857$ 13 1,192$
14 662$ 14 1,062$ 14 158,857$ 14 1,192$
15 662$ 15 1,062$ 15 158,857$ 15 1,192$
16 662$ 16 1,062$ 16 158,857$ 16 1,192$
17 662$ 17 1,062$ 17 158,857$ 17 1,192$
18 662$ 18 1,062$ 18 158,857$ 18 1,192$
19 662$ 19 1,062$ 19 158,857$ 19 1,192$
20 662$ 20 1,062$ 20 158,857$ 20 1,192$
21 662$ 21 1,062$ 21 158,857$ 21 1,406,740$
22 662$ 22 1,062$ 22 158,857$ 22 1,192$
23 662$ 23 1,062$ 23 158,857$ 23 1,192$
24 662$ 24 1,062$ 24 158,857$ 24 1,192$
25 662$ 25 1,062$ 25 158,857$ 25 1,192$
26 662$ 26 1,062$ 26 1,432,896$ 26 1,192$
27 662$ 27 1,062$ 27 158,857$ 27 1,192$
28 662$ 28 1,062$ 28 158,857$ 28 1,192$
29 662$ 29 1,062$ 29 158,857$ 29 1,192$
30 662$ 30 1,062$ 30 158,857$ 30 1,192$

Parking Lots
Conventional Asphalt PICP Parking Lots Porous Concrete Parking Lots Permeable Asphalt Parking Lots
Year Net Cost Year Net Cost Year Net Cost Year Net Cost
1 9,135,295$ 1 8,888,252$ 1 16,025,548$ 1 8,813,473$
2 8,270$ 2 1,031,292$ 2 4,272$ 2 7,687$
3 8,270$ 3 1,031,292$ 3 4,272$ 3 7,687$
4 8,270$ 4 1,031,292$ 4 4,272$ 4 7,687$
5 8,270$ 5 1,031,292$ 5 4,272$ 5 7,687$
6 8,270$ 6 1,031,292$ 6 4,272$ 6 7,687$
7 8,270$ 7 1,031,292$ 7 4,272$ 7 7,687$
8 8,270$ 8 1,031,292$ 8 4,272$ 8 7,687$
9 8,270$ 9 1,031,292$ 9 4,272$ 9 7,687$
10 8,270$ 10 1,031,292$ 10 4,272$ 10 7,687$
11 8,270$ 11 1,031,292$ 11 4,272$ 11 7,687$
12 8,270$ 12 1,031,292$ 12 4,272$ 12 7,687$
13 8,270$ 13 1,031,292$ 13 4,272$ 13 7,687$
14 8,270$ 14 1,031,292$ 14 4,272$ 14 7,687$
15 8,270$ 15 1,031,292$ 15 4,272$ 15 7,687$
16 8,270$ 16 1,031,292$ 16 4,272$ 16 7,687$
17 8,270$ 17 1,031,292$ 17 4,272$ 17 7,687$
18 8,270$ 18 1,031,292$ 18 4,272$ 18 7,687$
19 8,270$ 19 1,031,292$ 19 4,272$ 19 7,687$
20 8,270$ 20 1,031,292$ 20 4,272$ 20 7,687$
21 8,270$ 21 1,031,292$ 21 4,272$ 21 158,857$
22 8,270$ 22 1,031,292$ 22 4,272$ 22 158,857$
23 8,270$ 23 1,031,292$ 23 4,272$ 23 158,857$
24 8,270$ 24 1,031,292$ 24 4,272$ 24 158,857$
25 8,270$ 25 1,031,292$ 25 4,272$ 25 158,857$
26 9,135,295$ 26 9,302,485$ 26 4,272$ 26 9,132,645$
27 8,270$ 27 1,031,292$ 27 4,272$ 27 158,857$
28 8,270$ 28 1,031,292$ 28 4,272$ 28 158,857$
29 8,270$ 29 1,031,292$ 29 4,272$ 29 158,857$
30 8,270$ 30 1,031,292$ 30 4,272$ 30 158,857$

Roofs
Conventional Roof (Low Grade) Conventional Roof (High Grade) Extensive Green Roof Intensive Greef Roof
Year Net Cost Year Net Cost Year Net Cost Year Net Cost
1 3,220,649$ 1 5,291,067$ 1 13,471,679$ 1 12,537,080$
2 57,704$ 2 57,704$ 2 56,784$ 2 344,024$
3 57,704$ 3 57,704$ 3 56,784$ 3 344,024$
4 57,704$ 4 57,704$ 4 56,784$ 4 344,024$
5 57,704$ 5 57,704$ 5 56,784$ 5 344,024$
6 57,704$ 6 57,704$ 6 56,784$ 6 344,024$
7 57,704$ 7 57,704$ 7 56,784$ 7 344,024$
8 3,220,649$ 8 57,704$ 8 56,784$ 8 344,024$
9 57,704$ 9 57,704$ 9 56,784$ 9 344,024$
10 57,704$ 10 57,704$ 10 56,784$ 10 344,024$
11 57,704$ 11 57,704$ 11 56,784$ 11 344,024$
12 57,704$ 12 57,704$ 12 56,784$ 12 344,024$
13 57,704$ 13 57,704$ 13 56,784$ 13 344,024$
14 57,704$ 14 57,704$ 14 56,784$ 14 344,024$
15 3,220,649$ 15 57,704$ 15 56,784$ 15 344,024$
16 57,704$ 16 57,704$ 16 56,784$ 16 344,024$
17 57,704$ 17 57,704$ 17 56,784$ 17 344,024$
18 57,704$ 18 57,704$ 18 56,784$ 18 344,024$
19 57,704$ 19 57,704$ 19 56,784$ 19 344,024$
20 57,704$ 20 57,704$ 20 56,784$ 20 344,024$
21 57,704$ 21 5,291,067$ 21 56,784$ 21 344,024$
22 3,220,649$ 22 57,704$ 22 56,784$ 22 344,024$
23 57,704$ 23 57,704$ 23 56,784$ 23 344,024$
24 57,704$ 24 57,704$ 24 56,784$ 24 344,024$
25 57,704$ 25 57,704$ 25 56,784$ 25 344,024$
26 57,704$ 26 57,704$ 26 56,784$ 26 344,024$
27 57,704$ 27 57,704$ 27 56,784$ 27 344,024$
28 57,704$ 28 57,704$ 28 56,784$ 28 344,024$
29 3,220,649$ 29 57,704$ 29 56,784$ 29 344,024$
30 57,704$ 30 57,704$ 30 56,784$ 30 344,024$
31 57,704$ 31 57,704$ 31 56,784$ 31 344,024$
32 57,704$ 32 57,704$ 32 56,784$ 32 344,024$
33 57,704$ 33 57,704$ 33 56,784$ 33 344,024$
34 57,704$ 34 57,704$ 34 56,784$ 34 344,024$
35 57,704$ 35 57,704$ 35 56,784$ 35 344,024$
36 3,220,649$ 36 57,704$ 36 56,784$ 36 344,024$
37 57,704$ 37 57,704$ 37 56,784$ 37 344,024$
38 57,704$ 38 57,704$ 38 56,784$ 38 344,024$
39 57,704$ 39 57,704$ 39 56,784$ 39 344,024$
40 57,704$ 40 57,704$ 40 56,784$ 40 344,024$

Appendix C: Project Timeline
Task 11 12 13 14 15 18 19 20 21 22 25 26 27 28 29 1 2 3 4 5 8 9 10 11 12 15 16 17 18 19 22 23 24 25 26
Kick off Meeting
Expression of Interest
Establish Future Meeting Times with Client
Obtain Functional Designs from Client
Begin Review of Functional Designs
Project Proposal
Proposal Meeting with Client
Site Visit Preparation
Site Visit
Site Context
City of London Needs
Surface Analysis
Stormwater Management Inventory
Begin Preliminary Permeable Surface Research
Alternative Surface Research, Analysis and Summary
Net Water Savings
Financial Analysis
Conclusions and Recommendations
Draft Report Delivered to Client for Review
Draft Report Meeting with Client
Presentation to Client
Conducting Final Edits to Report
Final Report Delivered to Client
Task Timeframe
Milestones
Week 1 Week 2 Week 3
January
Week 4 Week 6 Week 7
February
Week 5

Project Timeline continued…
Task
Kick off Meeting
Expression of Interest
Establish Future Meeting Times with Client
Obtain Functional Designs from Client
Begin Review of Functional Designs
Project Proposal
Proposal Meeting with Client
Site Visit Preparation
Site Visit
Site Context
City of London Needs
Surface Analysis
Stormwater Management Inventory
Begin Preliminary Permeable Surface Research
Alternative Surface Research, Analysis and Summary
Net Water Savings
Financial Analysis
Conclusions and Recommendations
Draft Report Delivered to Client for Review
Draft Report Meeting with Client
Presentation to Client
Conducting Final Edits to Report
Final Report Delivered to Client
1 2 3 4 5 8 9 10 11 12 15 16 17 18 19 22 23 24 25 26 29 30 31 1 2 5 6 7 8 9 12 13 14 15 16 19 20 21 22 23
Week 15
April
Week 8 Week 9 Week 10 Week 11 Week 12
March
Week 13 Week 14

Jovian Design - Permeable Surface Stormwater Management Feasibility Study

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