Green Infrastructure Cost - Ontario Tender Costs Support Economic Analysis for Master Plans, Asset Management, Retrofit Strategies

Numerous green infrastructure, low impact development (LID) stormwater best management practices (BMPs), projects have been implemented in Ontario and across North America. To support planning studies and strategy development, capital costs for implementation are required.  The following table summarizes recent project costs, based largely in Ontario.

The average cost per treated hectare is $530,000 (total project costs are weighted by total project area).  The design volume for the majority of the projects is not available.

Ontario (and Alberta) Green Infrastructure Costs

The cost for these LID measures varies according to the type of feature as shown on the following chart that plots cost vs. service area (drainage catchment controlled).  Projects were grouped by type where possible, although some projects may incorporate more than one type in a treatment train.  The chart illustrates that Infiltration Trenches have the lowest cost per drainage area served. Rain Garden & Bioswales have the highest cost.

Ontario (and Alberta) Green Infrastructure Cost by Type of Low Impact Development Measure

Previous posts summarized costs from programs in the US.  The summary of 39 Ontario (and a couple Alberta) projects represent a total capital cost of $19.2M and a total service area of 36.2 hectares.  This area is comparable to the area of costed green infrastructure projects in the US EPA International BMP database.

The following table compares cost by LID type for three sources, the Philadelphia CSO control program, the ES UPA BMP database, and the compiled Ontario (and Alberta) tenders noted above.  The Philadelphia and the US EPA data both include design storage volume that may be considered for achieving different types of stormwater management goals (i.e., levels of service / performance outcomes).

Green Infrastructure Costs by Type and Design Volume - Philadelphia CSO Control Program, US EPA BMP Database, and Ontario (and Alberta) Completed Projects

Some key observations are that porous/permeable pavement has a relatively high cost per drainage area ($/ha), however the cost per storage volume is relatively low for the US EPA datasets - this warrants further review.  The Ontario/Alberta porous/permeable pavement costs per area are also relatively high, compared to other types.  Just like Ontario/Alberta data, Philadelphia and US EA data shows lowest cost per hectare for infiltration/exfiltration projects.  The infiltration/exfiltration cost per storage volume was relatively low for both the US EPA and Philadelphia datasets.

The Philadelphia green infrastructure projects achieve a high volume, equivalent to 38.9 mm over the catchment area draining to it.  In contrast, the US EPA storage volumes are equivalent to only 6.6 mm.  The Philadelphia projects are sized for 1-2 inches of storage to achieve CSO control.  In contrast the US EPA projects are sized to achieve other benefits, such as watershed protection.

While the Philadelphia cost per area is highest at $857,000 per hectare, which is 4.1 times the US EPA database cost of only $208,000 per hectare, the unit cost per storage is in fact less.  The Philadelphia unit cost is $22,000 per hectare-mm.  The US EPA cost is $32,000 per hectare-mm, reflecting lower cost efficiency for smaller installations perhaps.

Using these unit costs one can estimate the budget required to retrofit green infrastructure into older urban areas to improve stormwater management.  In Ontario, the urban area built by 1966 has been estimated to be 110,000 hectares (Ducks Unlimited mapping), and by year 2000 to be 852,000 hectares (provincial SOLRIS land use mapping v2).  Assuming that 200,000 hectares require significant storage to achieve flood control in older communities, the retrofit cost would be $171 billion, applying the $857,000/hectare unit cost.  Or to provide improved water quality and water balance controls to the year 2000 urban area, the retrofit cost would be $177 billion, applying the $208,000/hectare unit cost.  Both of those costs represent considerable sums, given the Ontario stormwater infrastructure deficit of about $6.8 billion - that is the retrofit cost would be over 25 times that current deficit.  Given that, a strategic approach to retrofitting older communities is required, including prioritization of retrofit areas, implementing on higher-performance sites (e.g., permeable soils), implementing on highest risk tributaries (sensitive habitat, infrastructure or property risks), and considering the most cost effective measures, e.g., higher volume/centralized facilities that exhibit lower unit costs for storage, and feature types with lowest unit costs (i.e., infiltration/exfiltration facilities, and (to be confirmed) porous/permeable pavement).  The operation and maintenance costs associated with porous/permeable pavement should also be considered in the development of a retrofit strategy (i.e., consider full lifecycle costs including both capital and operating costs).

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Update May 1, 2020

A few additional projects have been added to the cost table, including some updated costs for previously listed projects.  The added projects are the bottom six projects, representing an update for the Brampton County Court SNAP bioswale and the Newmarket Forest Glenn Drive LIDs.  The added projects are from the TRCA's cost review report to assess the updated LID lifecycle costing tool (LCCT Sensitivity Analysis https://sustainabletechnologies.ca/app/uploads/2020/03/LCCT-Sensitivity-Analysis_March2020.pdf). A total of 47 projects are now included.

The weighted cost per hectare has increased slightly to $540,000 per hectare of drainage area.

Across Ontario, the areas that could be retrofitted with LID controls is extensive. The new provincial SOLRIS land use data has been reviewed to assess what the province-wide retrofit cost could be considering:

1) Urban impervious area = 344,000 hectares

2) Transportation area = 295,000 hectares

3) Urban pervious area = 93,000 hectares

Controlling runoff for all such areas with green infrastructure LIDs would cost $395,000,000,000 - that is, $395 billion assuming a unit cost of $540,000 per hectare.

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The LID Cost Summary Table above presented costs per cubic metre so that the cost to achieve performance benefits through storage, e.g., water quality improvement, erosion stress reduction (water balance controls), or peak flow control, can be determined by those analyzing system performance. The costs in Philadelphia were $2,200 / cu.m for large volume controls (38.9 mm on average) while EPA BMP database costs were higher at $3,730 / cu.m for smaller controls (6.6 mm on average).

The added / revised Ontario projects include design volumes as well and so costs have been normalized by storage volume as shown below:

  

The Ontario cost per cubic metre is lower at $823.  This area-weighted cost reflect the very low unit cost of the Brampton bioretention rain garden of $297/cu.m - that cost is roughly an order of magnitude lower than the Philadelphia and US EPA BMP database costs for such features.  The median cost per cubic metre for these Ontario projects is $2,600, similar to the Philadelphia and US EPA cost.

Investing in Canada's Future: The Cost of Climate Adaptation - does infrastructure spending recommended in a new report for by IBC for FCM make sense?

Investing in Canada's Future: The Cost of Climate Adaptation,
Report by IBC and FCM, September 2019 

A new report by the Insurance Bureau of Canada attempts to answer an important question: How much should we invest in adaptation measures to prevent effects of climate change?

The report summary "Investing in Canada's Future: The Cost of Climate Adaptation" (link) suggests the following:

"The analysis determined that an average annual investment in municipal infrastructure and local adaptation measures of $5.3 billion is needed to adapt to climate change. In national terms, this represents an annual expenditure of 0.26% of GDP."

"Flood, erosion and permafrost melt are associated with the highest cost to GDP ratios at 1.25, 0.12 and 0.37, respectively. These climate risks require the greatest investment in adaptation."

The infographic summary (link) suggests that " the benefits of investing in community adaptation and resilience outweigh the cost of such investments by a ratio of 6 to 1".

Let's review this in terms of mitigation of flood damages.

The annual expected insured losses from hydrologic and meteorologic events in Canada is $0.7B based on Munich Re data.  Overall losses are $1.27B considering Munich Re ratios.  Over 100 years that some infrastructure lasts, that is $127B in losses, some that can be effectively mitigated or deferred.  If there is a 6:1 benefit:cost ratio to adaptation efforts, then spending $127B/6 = $21.2B would be the cost of the adaptation program to 'break even' (let's assume that is the capital cost and not operation and maintenance).

The IBC FCM study suggests spending of $5.3B per year - a lot more than the 'break even' number -and notes "What is needed now is an ambitious and long-term investment plan for disaster mitigation and adaptation charted along a time frame of not year-to-year, but for the next twenty years or longer."

Let's look at the numbers.

If we invest $5.3B per year for 20 years, that is $106B. So that is a benefit:cost ratio of $127B:$106B or 1:2:1.  If we invest $5.3B a year for 25 years, the cost exceeds the benefits.  That investment is a lot higher than what we would expect if we achieved a 6:1 benefit:cost ratio, spending only $21.2B.

If we consider that losses cannot be completely deferred with adaptation (as it is rarely 100% effective, and there may always be events that exceed design capacity leaving residual damages, and overall losses cannot be completely deferred), the potential benefits over 100 years may be only $70B, assuming all insured losses can be mitigated.  That means spending $5.3B a year for 20 years, or $106B will cost more than the benefits.

This should be carefully reviewed.  The value of all municipal storm and wastewater and bridge infrastructure in Canada is $418 B (see my 2018 CWWA presentation here). So investing $106B, or 25% of the value of all that infrastructure value is a lot.  Some municipality flood mitigation programs has been estimated at only 6% of asset value.

Setting investment levels appropriately is important and further analysis is needed.  It would also be worthwhile distinguishing between the cost to address today's infrastructure capacity and land use planning risks and future risks.  Much of Canada's current $0.7B in damages is due to existing level of service deficiencies and not future climate effects.

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In a previous study Green Analytics acknowledged the difference between damages due to economic growth and those due to future climate effects.  It would be worth looking at effects of future growth on damages and consider those in assessing infrastructure investment requirements.

Extreme Rainfall Trends in Canada - Engineering Climate Datasets for Long Term Climate Stations Show Increases and Decreases

Environment and Climate Change Canada's Engineering Climate Datasets includes trends in observed annual maximum rainfall over durations of 5 minutes to 24 hours.  Version 3.00 of the data was released in early 2019 (see Intensity-Duration-Frequency (IDF) Files https://climate.weather.gc.ca/prods_servs/engineering_e.html and Google Drive link to trend charts grouped by province and territory https://drive.google.com/drive/folders/1VzJdW7DUIA3mpqz8mA8jqG6LdCqy_UOF).  The following table shows trend direction and significance for stations across Canada.  It represents 3993 station-years of data, with an average of 47 years of data at 85 stations.

Some observations:

- out of 85 stations with trends over 9 durations, 7.9% of trends are statistically significant increases

- 1.8% of trends are statistically significant decreases

- the total of significant increases and decreases (7.9+1.8=9.7%) is mostly explained by chance (5% could be explained by random chance, due to the natural variability of the data)

- there are more increases than decreases with the exception of Ontario where southern Ontario has more decreases than increases, while northern Ontario has more decreases

- southern Ontario has 50% more significant decreases than increases

- Alberta is almost even with increases and decreases, and has no statistically significant increases, and just one significant decrease

- statistically significant increases are more prevalent for long durations over 1 hour (10%), than for short durations of 1 hour or less (6.4%) .. so significant increases for short durations are slightly above the % explained by randomness in the natural variability, in contrast, long durations have more significant increases than would be expected by chance

- statistically significant decreases are more prevalent for short durations of 1 hour or less (2.1%), than for long durations of over 1 hour (1.5%)

A review of these trends based on earlier v2.30 datasets, specifically stations with 20 years of record between 1965 and 2005, was presented by Shephard et. al in Atmosphere-Ocean in 2014:

"Summary statistics in Table 6 show that for all durations fewer than 5.6% and 3.4% of the total number of stations have significant increasing and decreasing trends in the AMS amounts, respectively. The highest percentage of stations with significant trends from any duration is 7.8%
(5.6% + 2.2%) for the 24-hour duration, which is close to the nominal 5% significance level. Based on this IDF single station analysis, and the more general single station climate results from the 1965–2005 period presented in Section 4a, we conclude that the annual maximum short duration rainfall values across Canada typically do not show a significant trend. Thus, for most of the single station IDF stations across Canada there is no evidence indicating that the stationarity assumption used in the traditional national EC IDF calculations has been violated. These results are not unexpected given the typical high variability and relatively short time series of the extreme short-duration rainfall observations."

Therefore Environment and Climate Change Canada find 'no evidence' that data used in IDF calculations is changing (values are stationary), and significant trends are generally no more than the natural variability would suggest.

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The version 3.1 datasets have just been released.  An assessment of trends at all stations is included in a new post: https://www.cityfloodmap.com/2020/05/annual-maximum-rainfall-trends-in.html - it also shows how trends have changed from older data sets (right chart) to the most recent sets (left chart) - no appreciable change.

Canadian Annual Maximum Rainfall Trends and Statistical Significance

The version 2.30 dataset was updated with data up to 2013 in 2014.  Version 3.00 was updated in early 2019 with some stations updated to 2017 but some with last update as far back as 2007.  The version 3.10 fills in many recent gaps and adds more stations - there were 565 in v2.30, 596 in v3.00 and now 651 stations in v3.00.  The v3.0 trends across Canada are shown below.

Annual Maximum Rainfall Trends in Canada - Environment Canada Engineering Climate Datasets v3.00 (released 2020) - trends per Environment Canada file idf_v3-10_2019_02_27_trends.txt