Green infrastructure can provide flood control, erosion control, and water quality benefits but the costs must be considered. A case study in Markham, Ontario found that a green infrastructure strategy was not cost-effective for flood control compared to conventional grey infrastructure strategies when considering capital and lifecycle costs. While green infrastructure provided benefits, the annual costs were much higher than the annual benefits. The study also highlighted concerns with infiltration from green infrastructure increasing risks of basement flooding and degradation of drinking water sources.

1. MECP Stormwater Design and Permissions Working Group
Cost Effectiveness
of LID Implementation
Robert J. Muir, M.A.Sc., P.Eng.
Manager, Stormwater, City of Markham
June 26, 2019 - Toronto, Ontario 1

2. OUTLINE
1) Regulations & Policies on Cost Effective Infrastructure
2) Ontario Capital Costs for Green Infrastructure
3) Ontario Lifecycle Costs and Economic Impacts
4) Grey and Green Benefits & Costs for Flood, Water
Quality and Erosion Mitigation
5) Green Infrastructure Infiltration & Flood Risk
2

3. Provincial Policy Statement (2014):
“Infrastructure … shall be provided in a coordinated, efficient and cost-effective
manner ….”
Infrastructure for Jobs and Prosperity Act (2015) O. Reg. 588/17 (2017):
Asset management plans must show “For each asset category, the lifecycle activities that
would need to be undertaken … and the costs of providing those activities.”
These activities must also consider “the lowest cost to maintain the current levels
of service”
Class Environmental Assessments (2015):
For wastewater projects “Economic Environment includes commercial and industrial land
uses and activities. It also includes the financial costs associated with the alternatives,
including construction, operation, maintenance, and property costs.”
Regulating Infrastructure Cost in Ontario
3
Provincial Policy Statement 2014 Infr. for Jobs and Prosperity O Reg 588/17 Municipal Class EAs

4. History of Cost-Benefit Analysis (CBA)
4
• Long-standing requirement to evaluate
feasibility of flood reduction projects:
Eckstein 1958: “Feasibility is interpreted to mean that ‘the
benefits, to whomever they may accrue, are in excess if
the estimated costs’, following a requirement specified in
the Flood Control Act of 1936.”
Watt 1989: “It is therefore reasonable to require that all
projects that provide or improve flood protection be
justified economically before public funds are allocated”
“benefits should exceed cost by a sufficient margin”
https://files.onhttps://nparc.nrc-cnrc.gc.ca/eng/view/accepted/?id=7b18d8c9-6c5f-425f-8338-ac4a24f8170bario.ca/infrastructure_update_2017-_eng_0.pdf
Watt 1989:

5. Ontario Green Infrastructure Policy
5
• Ministry of Environment and Climate
Change (now Ministry of Environment,
Conservation and Parks) draft LID
manual proposed Ontario-wide
targets. Did not address costs.
“Excessive costs alone shall
not be considered
an acceptable constraint”
(first draft)
Draft No. 2 LID Manual:
https://drive.google.com/open?id=1NHtrjCglDgox4tYISLU5LLZYS32Ea4MN

6. Made-in-Ontario Environment Plan
• “This plan will ensure we balance a
healthy environment with a healthy
economy.”
• Highlights frustration of taxpayers who see
“hard-earned tax-dollars being put towards
policies and programs that don’t deliver
results”.
• Cost-benefit analysis can show where
results (benefits) are achieved effectively
relative to economic investment.
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https://prod-environmental-registry.s3.amazonaws.com/2018-11/EnvironmentPlan.pdf
Ontario Environment Plan:

7. OSPE Bill 139 Comments on Green Infr. Cost
• “Estimates suggest that green infrastructure adaptation costs could be as
high as $400,000 per hectare, inclusive of recently tendered construction
projects. This means that the long-term province-wide costs to
developers and municipalities—and, ultimately, the end consumer and
economy—total hundreds of billions of dollars.” (OSPE - Oct. 2017)
Hectares Urban Land x Cost Per ha = Initial Capital Cost
852,000 x $390,000 = $332 B
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https://drive.google.com/open?id=1az42-2TZrcmRm2uHVcxG6mc3LBtb8vv-
https://www.cityfloodmap.com/2016/11/green-infrastructure-solution-to-urban.html
OSPE Bill 139 Comments:
Initial Cost Assessment :

8. Green Infrastructure Capital Cost Review
• Costs from various sources have confirmed magnitude of cost issue and
need to assess lifecycle costs and cost effectiveness (over 1200 projects).
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https://www.cityfloodmap.com/2018/05/are-lids-financially-sustainable-in.html
https://www.cityfloodmap.com/2018/07/green-infrastructure-capital-and.html
Ontario Tenders :
Philadelphia, NY Costs :
Ontario Tenders Philadelphia Clean Waters
$575,000 per ha
$568,000 per ha
$783,000 per imp. ha
New York State

9. Higher Green Infr. Unit Costs for Flood Control
• “Estimates suggest that green infrastructure adaptation costs could be as
high as $400,000 per hectare, inclusive of recently tendered construction
projects. This means that the long-term province-wide costs to
developers and municipalities—and, ultimately, the end consumer and
economy—total hundreds of billions of dollars.” (Oct. 2017)
Hectares Urban Land x Cost Per ha = Initial Capital Cost
852,000 x $726,000 = $619 B
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https://drive.google.com/open?id=1XFCCwHe8R6VQ5J4kZ-hHyZVSdnL8zuYf
Unit Cost for Flood Control (2019 WEAO Paper) :

10. Philadelphia Clean Waters Compiled Costs
• Weighted program cost $857k / hectare, $2200/m3 (2018$)
10
https://www.cityfloodmap.com/2019/06/low-impact-development-capital-costs.html
Unit Cost for Philadelphia LIDs :

11. Philadelphia Clean Waters Costs by LID Type
• Cost per drainage area & storage volume for infiltration trenches, pervious
pavement, rain gardens and tree trenches (2018$). Avg. 39 mm storage.
11

12. OSPE Comments on Long-Term Infr. Plan 2017
• “green infrastructure must be viewed through the same lens as
conventional infrastructure, adhering to established asset management
principles and full cost accounting—meaning it must be addressed up-front
and directly, considering system-wide costs.” (Jan. 2018)
Full-cost accounting includes : Operation and maintenance costs (inspection,
routine intervention /restoration), depreciation
(long-term replacement).
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https://drive.google.com/open?id=1_ehoK0opvzeBFLv1Vrc6QFIbS9B5qFA8
https://www.cityfloodmap.com/2018/07/green-infrastructure-capital-and.html
LTIP Comments:
Lifecycle Cost Assessment :

13. Lifecycle Costs for Green Infrastructure - Concerning
13
https://www.cityfloodmap.com/2018/07/green-infrastructure-capital-and.html
Lifecycle Cost Assessment :
Capital cost - 860,000 / imp.ha
O&M cost - $20,000/imp.ha/yr
Service life – 50 years (avg.)
Annual Cost – $ 15.8 B
- $3,100 / household / year
- 3% of household
disposable income
Current Ontario stormwater
deficit is $6.8 B.

14. Damages & ROI on Infrastructure – Industry Research
• Relies only on ‘meta-analysis’:
– no local data or ignores published
local data (e.g., Pelly L. damages)
– no engineering analysis (Autocase
Metrolinx TEV, Green Team Analytics)
– incomplete benefit/cost assessments
(omits benefits) & mixes-up one-time
capital & annual costs (e.g., Oakville)
– extrapolates atypical wetland settings
to apply to broad urban/rural areas
– ‘rebrands’ quality control projects as
life and money saving flood projects
– ignores environmental constraints &
impacts with wetland flood control
https://goo.gl/xbxvyT
https://goo.gl/epVuBe
Green Team Report Review:
ICCA Wetland Report Review:
14
https://goo.gl/Y3vWzx
IBC Wetland Report Review: :

15. Meta-Analysis & Press Promotion – Industry Research
• Overstates ‘meta-analysis’ of benefits as
real “Performance monitoring results” for
flood damage reduction (e.g., Pelly L.
benefits page 42)
• Omits cost-effectiveness of recommended
physical interventions: “cost rankings are
not normalized with consideration of
performance effectiveness” (Section 4.4)
• However Press Release (Jan. 18, 2019)
promotes recommendations as “solutions
that can be deployed practically and cost-
effectively within communities”
15
https://goo.gl/Y3vWzx
ICCA Weathering the Storm Report Review: :

16. 16
National Research Council Guidelines
• NRC is developing Guidelines on
Undertaking a Comprehensive Analysis
of Benefits, Costs and Uncertainties of
Storm Drainage Infrastructure in a
Changing Climate
https://drive.google.com/open?id=1W8CT2iEs-vdE-KhT87B441k8ciQZ13SL
National Research Council Guidelines Scope of Work :

17. 17
National
Research
Council
Guidelines
• Case studies
will show how
benefit/cost
ratios can be
developed for
city-wide
strategies
and projects.

18. Markham Case Study – Grey/Green Benefits & Costs
• Analysis of city-wide Flood Control Program
costs and benefits initiated to:
i) estimate DMAF project Return on
Investment for flood control
ii) evaluate green infrastructure (LID) cost-
effectiveness for:
• Flood control
• Watercourse erosion repair mitigation
• Water quality improvements (based on
willingness to pay)
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https://www.markham.ca/wps/portal/home/neighbourhood-services/water-sewer/projects-and-programs/06-projects-and-programs
Markham Flood Control :
https://www.cityfloodmap.com/2019/02/an-economic-analysis-of-green-v-grey.html
WEAO paper :

19. Markham Case Study – Strategies (Flood Control)
• Focus on 25% of city (pre-1980s areas)
(brown shaded areas in image)
19
• Strategy A
grey infrastructure (current
program incl. one central wetland)
• Strategy C
green infrastructure
• Strategy D
90% grey
10% green
West Thornhill
Unionville
Markham
Village
Steeles Ave. E
Hwy 407
Pre-1978 Subdivision Registration – No Major Drainage Design, No Water Quality or Erosion Control

20. Markham Case Study – Strategies (Erosion Control)
• Erosion restoration
priorities are within
pre-1980’s servicing
areas:
– sanitary trunk risks
along tributaries
– no upstream SWM
controls
• Erosion stress
reduction (water
balance) not a priority
in post-80’s areas.
20
West Thornhill
Unionville
Markham
Village
City Wide Erosion
Prioritization Study
and 5 Year Capital
Plan
April 2019

21. Markham Case Study - Benefits
• Flood control benefits
– Deferred damages based on
scaled regional reported claims
• Erosion control benefits
– Lower creek repairs based on
lifecycle costs (green only)
• Watershed quality benefits
– Willingness-to-pay for water quality
improvements based on Rouge R.
source control study (green only)
21
https://www.cityfloodmap.com/2019/02/an-economic-analysis-of-green-v-grey.html
WEAO paper :

22. Markham Case Study - Costs
• Grey infrastructure
– Capital - completed, tendered,
& designed projects, Class EA
estimates, program costs
– O&M – equivalent to existing
lifecycle program costs
• Green infrastructure
– Capital – average of unit cost for
all LID types (excl. green roof)
– O&M – per Philadelphia clean
waters pilot lifecycle costs
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23. 1
10
100
1000
10000
Downspout
Program.
Backwater
Valve Pgm.
Sanitary
Upgrades
Storm
Upgrades
Green Infr.
Retrofit Option
Markham Flood Control Program Activities and Costs
Cost
($M)
$3 M
$1300/ha
$27 M
$11,000/ha
$253 M
$120,000/ha
$1.7 B
$726,000/ha

24. 1
10
100
1000
10000
Downspout
Program.
Backwater
Valve Pgm.
Sanitary
Upgrades
Storm
Upgrades
Green Infr.
Retrofit Option
Flood Control Strategies - 50 Shades of Grey to Green
Cost
($M)
Strategy A (grey) Strategy C (green)
Strategy D
(grey + green)

25. Annual Costs and Benefits
25
-70 -60 -50 -40 -30 -20 -10 0 10 20
-70 -60 -50 -40 -30 -20 -10 0 10 20
Strategy C
Strategy B
Strategy A
Flood Benefit Erosion Benefit Quality Benefit Cost
Strategy A
(grey)
Strategy C
(green)
Strategy D
(grey + green)
Benefits/year $M
Cost/year $M
(insured losses only) (“willingness to pay”)

26. Annual Costs and Benefits
26
-70 -60 -50 -40 -30 -20 -10 0 10 20
-70 -60 -50 -40 -30 -20 -10 0 10 20
Strategy C
Strategy B
Strategy A
Flood Benefit Erosion Benefit Quality Benefit Cost
Strategy A
(grey)
Strategy C
(green)
Strategy D
(grey + green)
Benefits/year $M
Cost/year $M
Benefit / Cost = 2.52 (100% flood)
Benefit / Cost = 0.27 (41% flood)
Benefit / Cost = 0.91 (88% flood)
Residential Stormwater Fee = $ 3,800 /yr
Residential Stormwater Fee = $ 47 / yr
(insured losses only) (“willingness to pay”)
Residential Stormwater Fee = $ 150 /yr

27. 27
Infiltration & Flood Risk from Green Infrastructure
• Source control BMP infiltration risks on
sewer systems were identified in 1992
• Workshop of Ontario experts reviewed
1991 Interim Guidelines that first
introduced green infrastructure for new
development water quality control.
https://drive.google.com/open?id=1dNFzxZxlzxUx-g9DzvVHSvwceXhddkCq
https://www.slideshare.net/RobertMuir3/robert-muir-green-infrastructure-for-climate-adaptation-nrc-workshop-on-urban-rural-storm-flooding-february-27-2018-ottawa
OSPE Watershed Planning Guidance Comments :
National Research Council Workshop Feb 2018 :
https://drive.google.com/open?id=0B9bXiDM6h5ViNkN1NTVweGZZMG8
1992 Workshop Summary :

28. 28
Infiltration & Flood Risk from Green Infrastructure
• Infiltration in
sanitary sewers
explains > 60% of
sewer back-up risk
at a postal code
spatial scale.
• Green infrastructure
relies on runoff
infiltration and
increases core
stress driving
basement flooding.
Sanitary Sewer Capacity
Back-up
Risk
Sanitary
Infiltration
Peak Flow Rate
Infiltration Drives Basement
Back-Up Risks in the Most Flood-
Prone, Partially-Separated Sewer
Service Areas
10 Yrs Continuous Flow Modelling (all areas)
All-pipe Hydraulic Model (2 Master Plans)
Moderate
High

29. 29
Green Infrastructure Water Supply Risks
• Infiltration of runoff violates MECP Procedure F-6-1 to prevent ‘sewage’
(runoff in OWRA) discharge over municipal potable water supply lines.
• Journal of Toxicology and Environmental Health publication Sources,
Pathways, and Relative Risks of Contaminants in Surface Water and
Groundwater: A Perspective Prepared for the Walkerton Inquiry
summarizes contamination types and indicates that presumably ‘clean’
runoff sources such as roof runoff can, contrary to local LID design
guidelines, exhibit high contaminant loads.
http://www.hydrorelief.org/frackdata/references/RisksContamWater.pdf
Journal of Toxicology and Environmental Health :
https://www.ontario.ca/page/f-6-1-procedures-govern-separation-sewers-and-watermains
F-6-1 Procedures to Govern Separation of Sewers and Watermains :
https://drive.google.com/open?id=1T3vXEJ_nBi8e30KpcawVTfFPKx7A6y_v
WEAO MOECC LID Guidance review July 2017 :

30. 30
Green Infrastructure Water Supply Risks
• Infiltration of runoff increases
chloride concentrations in
aquifers. Municipal wells in
Waterloo, Kitchener and
Cambridge exceed Ontario
objectives and are increasing.
• Green infrastructure that
infiltrates road, and parking lot
runoff degrades drinking water
source quality.
https://www.therecord.com/news-story/9046980-chloride-levels-are-rising-in-waterloo-region-drinking-water/
Region of Waterloo Chloride Levels:

31. Conclusions
• System-wide capital cost and lifecycle cost assessment shows universal
implementation of green infrastructure (e.g., retrofitting 852,000
untreated hectares in Ontario) is financially unrealistic.
– > ½ trillion dollars in capital (opportunity cost for other priorities)
– $3100 / household / year = significant financial impact
• Benefit/cost ratio for LIDs unfavourable for flood control – Markham
Case Study with focused implementation shows benefits less than costs.
• Benefit/cost ratio for LIDs unfavourable for water quality
improvements – ‘willingness to pay’ benefits less than costs.
• Green infrastructure infiltration stress on sanitary sewers increases
basement back-up risk in older service areas - shows focused
implementation should be avoided. 31

32. Conclusions … Continued
• Favourable LID green infrastructure benefit/cost analysis based
only on unreliable ‘meta-analysis’, with incomplete engineering input,
and atypical ‘pilot’ studies that do not support universal claims.
• Green infrastructure runoff infiltration water supply impacts
overlooked by proponents focused on surface water systems:
– Clean runoff sources have high metals and pathogen concentrations
receiving only moderate treatment (Walkerton Inquiry)
– Infiltrated chlorides accelerate corrosion/deterioration of ductile iron
watermains, reducing asset life and increasing break risk (high chlorides
decrease soil resistivity)
– Infiltrated chlorides degrade aquifer and municipal well quality (e.g.,
Waterloo, Kitchener, Cambridge)
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33. Thank You
Questions ?
More Rob :
Blog: www.CityFloodMap.com
Podcast: Open During Construction on iTunes
Twitter: @RobertMuir_PEng
More City of Markham :
Web: www.markham.ca
Twitter: @CityofMarkham
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