Storm Water Management

Case Summary

Where land is undeveloped, runoff from storms can be absorbed by soil and roots and normally does not cause flooding or other problems except in extreme cases. In cities, however, the extensive construction of roads, parking lots, and buildings diminishes the area of land able to absorb runoff, and is instead diverted into a storm water system after picking up residues of oil, animal waste, fertilizers, pesticides, road salt, exhaust chemicals, and other contaminants. In many areas, especially with older sewage systems, the storm water combines with sewage in "combined sewers." Ideally, the combined sewer water is all treated before being released, but during heavy rain or melting events, the sudden spike in volume exceeds capacity of the treatment plants and the excess is released untreated, polluting the waterways where this waste is dumped. This case study documents some of the innovative approaches being undertaken to mitigate this problem in Chilliwack, BC, and Toronto, ON.

Sustainable Development Characteristics

There are a number of approaches to mitigating wastewater pollution, ranging from source to end-of-pipe, small to large-scale, low to high-tech, public education, and building large public works. In order to capture a wide range of innovative approaches to reducing the problem, this case study looks at the medium-sized community of Chilliwack, BC and the large urban area of Toronto, ON. How a community treats all of its waste, including wastewater, is an essential component of sustainable community development, and indeed adjacent communities, particularly where water systems and watersheds are interconnected .


The Policy and Design Criteria for Surface Water Management in Chilliwack1 is a policy for surface water management that aims to replicate the natural infiltration rate of the land surface to prevent peak flows in flooding in streams within the municipality. The policy is also tied into a process of stream classification based on the water course’s suitability for fish habitat, its flow regime and cross sectional characteristics. A parallel policy to the surface water management is, therefore, the derivation of suitable riparian setbacks to protect stream quality.

The policy aims to transfer the costs of drainage to the private developers of new subdivisions and property improvers and away from the city. This means that developers are responsible for designing systems that retain water within a new development area and release it in a slow and controlled fashion into the soil, and ultimately the natural drainage system. The standard for this has been set at a flow rate of less than 1 litre / sec from the outflow from a subdivision.


The Great Lakes hold one fifth of the world's fresh water, covering 23,000 km2 and draining an area of 745,900 km2, making them ecologically important on a global scale. Its shores are home to 35 million residents, almost half of whom draw their drinking water directly from the lakes (Sierra Legal Defence Fund, 2006). Although some improvements have been made in recent decades, the Great Lakes are still a disposal area for a wide range of industrial, residential, and public effluents. Since only about 1% of the Great Lakes' water is changed every year, the effects of water pollution are cumulative and long-lasting (Gorrie, 2006). Of all the pollution sources in the Great Lakes, one of the most significant is untreated sewage: the 20 cities studied in the Great Lakes Sewage Report Card (Sierra Legal Defence Fund, 2006) dump 92 billion litres of untreated sewage annually into the Great Lakes.

Toronto ranked 12th of these 20 cities for sewage treatment performance, with particularly low performance on combined sewer overflows (containing a mixture of sanitary and storm water), occuring 30-50 times per year for a total of 9 billion litres.

In order to mitigate these impacts, in 2003 Toronto embarked on a 25-year, 1-billion dollar Wet Weather Flow Management Master Plan. The basic goal of this Plan is to meet the Provincial Water Quality Objectives within the City of Toronto area surface waters. More specifically, it aims to (City of Toronto, 2006):

  • improve the water quality at public beaches so the water is safely swimmable all summer,
  • eliminate discharges from combined sewer overflows,
  • reduce basement flooding caused by the backing up of overflowing sewers,
  • protect of City infrastructure from stream erosion,
  • restore degraded local streams,
  • improve stream water quality,
  • reduce algae growth along the waterfronts and in streams, and
  • restore aquatic habitat.

The Plan includes efforts at every stage of the wastewater management system: source, conveyance (moving of the waste water), and end-of-pipe facilities. This plan is part of a longer-term 100-year watershed-wide strategy to mitigate the impacts of wet weather flow. The size and population of Toronto present both a significant burden on the local watershed and a particular opportunity to develop new solutions given the significant financial and human resources available to the City.

Critical Success Factors


  • Based on Provincial guidance2, and with their support, and the support of federal ministries and consultants from the private sector.
  • Systems approach – operates from the moment water reaches the ground.
  • Considers design issues from watershed scale to individual buildings.
  • Uses research and data to identify critical areas.
  • The provision of design guidance and open and transparent standards for developers.


Successful implementation of Toronto's 25-year water pollution plan will depend on:

  • Continued and increasing funding for capital projects and ongoing programs from the City and the Province. This is critical both to the rate at which projects are completed, and so the City can take advantage of opportunities to replace aging combined sewers with separate storm and sanitary sewers when the pipes need replacing.
  • Success of public education campaigns in promoting less polluting individual habits (ie cleaning up animal waste and not flushing toxic chemicals down drains and sewer grates) and source stormwater management such as downspout disconnection, and
  • Continuing political will to improve water quality in Toronto rivers and Lake Ontario.

Community Contacts

Ernie Knight
Subdivision Application Manager
8550 Young Road
Chilliwack, BC
V2P 8A4
1 604 793 2906

Lisa Turnbull
Toronto and Region Conservation Authority Project Manager for the Community Program for Stormwater Management Program
Tel: 416-661-6600 x 5325
e mail:

What Worked?


  • Although no monitoring has taken place, observations by officers of the City of Chilliwack reveal that flood events have been reduced and water quality has been improved.
  • The regulatory regime of applying the standards in all new developments, combined with a fair and equal application of the standards meant that local developers were happy to undertake the implementation of the policy once an initial period of complaint and lobbying against the policy was over.


  • Combination of many different approaches at different levels of the wastewater system
  • Public education may serve both to reduce individual polluting behaviors and drive support for expensive public works projects
  • New Deal for Cities has provided new capital funding for expensive projects such as large overflow storage basins
  • Long-term commitment to public education and improvements to existing practice and infrastructure
  • Ongoing monitoring will assess the long-term effectiveness of the plan, but it is too early yet to separate normal climatic variations from Plan improvements.

What Didn’t Work?


  • The initial application of the policy on hill slopes was rejected as the infiltration of water into the slope is contrary to geotechnical safety considerations. Therefore a policy of water retention not infiltration was instigated, with water being released into water courses, or pipes down slope and infiltrated elsewhere.
  • City Operations engineers vetoed the use of open lagoon storage systems due to the increased maintenance costs, liability issues and fears over the West Nile Virus associated with open water.
  • It was initially hoped that existing developments could be retrofitted, but this has proven difficult to implement to the costs put on home owners. As a result when a change to an existing development is carried out home owners are encouraged to retrofit a drainage system and any extension to the building or new building must incorporate retention and infiltration drainage.


  • Large networks of environmentally damaging public infrastructure have been built, which will be expensive and time-consuming to upgrade
  • Beaches may remain too polluted for swimming even after all point sources are controlled. The City spent over $75 million on a huge underground CSO storage tank to protect its western beaches, but they still frequently have too high E. coli levels for swimming. Some evidence suggests that a high waterfowl population and flow from the rivers are now the primary sources of E. coli contamination. The City is now investigating possibilities for redirecting river flow away from beaches and controlling waterfowl populations. Toronto's rivers continue to be polluted by combined sewer outfalls within and outside of city limits, and agriculture outside of city limits. New suburban development in the Humber River headwaters are expected to further degrade the river's water quality (
  • The free, voluntary downspout disconnection program has been fairly popular, disconnecting about 2,300 homes per year at an average cost of $1,100 per house. However at this rate, it would take 22 years to reach its target of 40% of downspouts disconnected. City Council has proposed mandatory downspout disconnection with 50% of the cost up to $300 covered by the city, which would disconnect 80% of homes within 10 years. This proposal has been sharply criticized by some councillors and others as a veiled tax, and will be going to community consultations. It is yet unclear whether the mandatory program will pass council (

Financial Costs and Funding Sources


The initial budget for the policy formulation and the development of design criteria ran to approximately $700,000. Half of this was met by the city, the other half through a number of grants including:

The University of British Columbia also provided resources to help with the initial monitoring and surveying.

Since the implementation of the policy little financial data are available, much of the implementation costs are carried by the private sector developers now responsible for putting the drainage systems in place. The initial figures for the implementation of a five year plan were budgeted at $1.7M (Dipak Basu, former Development Engineer for the City of Chilliwack, in a presentation given in 2004 at Royal Roads University), but this budget has now been abandoned as key personnel have retired and the time and resources are not available to do more than keep up with the pace of new development.

Costs if implementation are carried by developers who add the costs to their development budgets, and then presumably onto future home owners. The responsibility to maintenance is then passed to the City, or to strata committees depending on the type of development. There is no information on the relative costs of maintenance for the infiltration infrastructure relative to the traditional storm sewer.


The cost of Toronto's 25-year Wet Weather Flow Management Plan is estimated at $40,000,000 per year ( The budget for the first five years of the plan (2003 - 2007), based on the detailed breakdown in the 2004-2005 implementation report (City of Toronto, 2006b) is summarized in table 1. This table does not include an additional $36,000,000 spent on stream restoration, $1,000,000 on shoreline restoration, and $55,510,000 on basement flooding measures. The program is funded from the budget of the City of Toronto. Total funding for wastewater and water programs is predicted by the City to more than double from $249,500,000 in 2005 to $502,000,000 by 2009 (City of Toronto, 2005).

Capital Cost ($) Operating Cost ($) Total Cost ($)
Public Education 6,000,000 6,000,000
Source Controls 21,000,000 21,000,000
Conveyance Controls 8,000,000 30,000 8,030,000
End of Pipe Facilities 38,075,000 9,700,000 47,775,000
Monitoring 1,670,000 1,670,000

Table 1: Toronto Wet Weather Flow Management Plan costs

Detailed background for case study


Chilliwack is an agricultural community of 70,000 running along the south bank of the Fraser River in BC. The community recognises three creek based watershed planning areas:

  • Hope Slough in the eastern part of the municipality
  • Chilliwack Creek in the central part of the municipality
  • Chilliwack Western Areas.

Throughout the municipality there are 600 km of streams in a land area of 260 km2. The goal of the project was to create an urban form that simulated similar run-off profiles to the natural forest eco-system – or a land surface that is only 10% impermeable. Or to put it another way a land surface that can infiltrate the first 30mm of rainfall in any precipitation event.

The Department of Fisheries and Oceans has a policy of restricting development along riparian zones to protect fish habitat, this led the City of Chilliwack to formulate classification of streams to allow for development to create appropriate riparian set-backs and also instigate a more sustainable surface water management system that improved water quality entering water courses and reduced flood events.

Chillwack was selected as a case study for the application of Stormwater Planning: A Guidebook for British Columbia2 funded jointly by the Provincial and Federal Governments and forms part of the Georgia Basin Ecosystem Initiative. Chilliwack has been concerned about planning for stormwater management since 1995, when it released guidelines stating that:

    all new development must restrict flows from the subdivision or development to pre-development volumes.

The goal of the current policy is to:

    implement integrated stormwater management that maintains or restores the water balance and water quality characteristics of a healthy watershed, manages flooding and geotechnical risks to protect life and property, and improves fish habitat values overtime.”

This is supported by 5 management objectives.

  1. To manage development to maintain stormwater characteristics that emulate the pre-development natural watershed.
  2. To predict the cumulative stormwater impacts of development and to integrate this information with other economic, land use and sustainability objectives and policies when considering land use change.
  3. To regulate watershed-specific performance targets for rainfall capture, runoff control, and flood risk management during development, and to refine these targets over time through an adaptive management program.
  4. To identify, by example and pilot studies, means of meeting the performance targets by application of best management practices, and to remove barriers to use of these practices.
  5. To support innovation that leads to affordable, practical stormwater solutions and to increased awareness and application of these solutions.

The objectives and goal are supported by a master planning exercise providing strategic plans for surface water management at creek watershed and sub-watershed levels and a functional plan for individual creek catchment areas.

Design criteria are implemented so that at the site level rain fall is kept on site to allow it to infiltrate into the natural subsurface hydrological systems. At a neighbourhood scale runoff from a subdivision is held in order to reduce storm run-off peaks into the municipal drainage system and creek network. This has the goal of reducing flooding in the municipality. These also reflect the severity of rain events. Most rainfall events should be exclusively retained on site and infiltrated into subsurface hydrological system. Moderate events will be stored within neighbourhood in retention ponds, extreme events will be safely conveyed into and through the natural surface water system avoiding flooding in urban areas.

Not only does this reduce flood risk, but also prevents surface run off from washing pollutants into the creek system from road surfaces and residential lots. In addition holding water in the subsurface and on site allows for water recycling by households and aids the recharging of the groundwater. Although this approach, termed the 'water balance approach', has been tested in Chilliwack no private developer has used it to date, preferring to implement there own design solutions.

Design lessons from the policy formulation process included the provision of a minimum depth of spoil in subdivision landscaping. Careful design of drainage on driveways to ensure water is channelled into soak-a-ways rather than into storm drains. Pilot projects in five new sub-divisions between 2001 and 2003 were implemented to test some of the design criteria. These included:

  1. Removing curbs and gutters from roads.
  2. Installing ‘French Drains’ in a grass verge along the road side. A French drain is, at its simplest, a trench filled with gravel that allows water to drain away from the surface quickly but allows it to infiltrate into the subsurface rather than in to a drainage system.
  3. Installing a retention pond at the lowest point of altitude to contain water during larger rainfall events, and release it slowly into the natural drainage system.
  4. Landscaping with gentle grades of slope to reduce the loss of soil and sediment into the drainage system.

Narrower roads also have other benefit by reducing development costs and reducing the amount of clearing of natural vegetation required. The data from the test subdivisions has confirmed that the drainage is adequate for all storm events and prevents flooding in the downtown and other sensitive areas.

Since the formulation of the design guide and policy developers have been obliged to implement water retention and infiltrations systems in all new developments. This has usually been in the form of permeable pipes and storage tanks allowing slow release of water into the ground and adjacent water courses. There are however exception to this. On the hillsides within the municipality the infiltration into the soil was not an option as slope stability concerns become an issue. Therefore impermeable concrete storage tanks have been used to hold the water which is then released in a controlled fashion in water courses.



Toronto is a large urban centre of 2.6 million people and a $7.6 billion operating budget (City of Toronto, 2006). Its municipal sewer and storm water systems are extensive: the storm water system is a 4,500km network with 2,600 outfalls (, connected in an unknown number of locations to the sanitary waste system which handles 400 billion litres of sewage annually.

Its land base is almost entirely developed except for preserved areas, and residential and commercial development is in the form of re-development of already urban areas, rather than the building of new subdivisions as in Chilliwack. Due to the high degree of existing development in Toronto, and the greater budgetary resources available, the strategies available for wastewater pollution mitigation are both limited and more extensive in comparison with those available to Chilliwack.

Goals and Strategies

In developing its Wet Weather Flow Management Master Plan, Toronto considered an extensive list of available strategies and technologies, under the categories (City of Toronto, 2003):

  1. At source control measures that are at the beginning of a drainage system or generally at the lot level;
  2. Conveyance controls that are located within the drainage system where flows are concentrated and are being conveyed along a corridor;
  3. End-of-pipe controls that are at the end of a flow conveyance route;
  4. Management / operational practices which are not site specific and are generally “watershed wide” measures; and
  5. Special measures that are not actual “control works” but provide an enhancement that will provide a watershed or stream improvement.

This 275-page document outlines 86 different wastewater management strategies, explains what each one is, its mechanism of effectiveness, expected benefits, related management plans, application requirements, proven effectiveness / experience elsewhere, cost considerations, and references for further information. The document also lists which of the 13 objectives of the plan each strategy addresses:

Water quality

  • meet guidelines for water and sediment quality
  • virtually eliminate toxics through pollution prevention
  • improve water quality in rivers and the lake for beaches that are healthy for swimming
  • improve aesthetics

Water quantity

  • preserve and re-establish a natural hydrologic cycle
  • reduce erosion impacts on habitats and property
  • eliminate or minimize threats to life and property from flooding

Natural areas and wildlife

  • protect, enhance and restore natural features (eg., wetlands) and functions
  • achieve healthy aquatic communities
  • reduce fish contamination

Sewer system

  • eliminate discharges of sanitary sewage
  • reduce infiltration and inflow to sanitary sewers
  • reduce basement flooding

It is a comprehensive and valuable resource of available wastewater management strategies. Selection and adoption of these strategies is decided by a 24-member steering committee including public members, city councillors and staff, and representatives of provincial agencies and interested NGOs (City of Toronto, 2003b). The strategies this committee has selected include both large and small scale projects, both centralized and diffuse (Toronto Water - Community Program for Stormwater Management There are too many projects to list in this case study, but the following is a brief summary from the 2004-2005 Implementation Report.

Public Education

  • multifaceted advertising campaign to promote individual water pollution reduction through measures such as downspout disconnection, reducing impermeable surface area (ie pavement and concrete), cleaning up pet waste, avoiding oil spills from vehicle maintenance, and reducing household use of toxic chemicals.

Toronto Wastewater Ad

Ad from the Toronto wastewater education campaign.  See this and other samples at
  • blue flag program: an international accreditation program for public beaches, which Toronto has sought and earned for several of its beaches, and uses for public education towards individual pollution reduction.
  • Community Program for Stormwater Management (CPSWM): $250,000 per year to fund small-scale, community-led stormwater management projects costing between $1,000 and $25,000.

Source Controls and Pollution Reduction

  • Downspout disconnection program: City has an advertising program and provides city staff to disconnect roof downspouts from the sewer system for free. Disconnected 3,400 downspouts in 2004 and 2005. Downspout disconnection will eventually become mandatory for all homes.
  • Green roofs: The City has committed to installing green roofs on City buildings where practical, and has adopted a strategy of incentives to private owners to construct or retrofit existing buildings with green roofs.
  • Rainwater Harvesting (RWH): This refers to using rainwater as a resource for non-potable uses such as irrigation and toilet-flushing. The City hosted a RWH workshop in 2005 to identify and promote opportunities, is working with Exhibition Place to develop a demonstration and public education project, and is promoting the use of RWH in new public and private developments.
  • Catchbasin Cleaning: Catchbasins and stormwater inlets are cleaned annually for arterial roads and biannually for local roads to reduce pollution concentrations
  • Improved Street Cleaning: Replacing existing street sweepers with regenerative-air type sweepers which are more effective at reducing runoff toxicity.

Conveyance Controls

  • Perforated pipe system: Can be installed in roadways as they are being constructed or reconstructed to reduce runoff temperature and remove some pollutants contained in roadway stormwater. Several of these projects are being planned starting in 2007.
  • Grass swale and roadside ditches: only feasible in low-density suburban and rural areas or along highways, as described for Chilliwack. Toronto is "strongly promoting" their use in new suburban developments and their preservation where already existing, and has incorporated them into several road reconstructions.
  • Sewer separation: separating combined sanitary and wastewater sewer pipes into separate pipes. It is very expensive and causes lengthy road disruptions, so is only being done to reduce basement flooding on a case by case basis. As existing sewer pipes need replacement, the City will consider replacing them with separate storm and sanitary pipes, also on a case by case basis.

End-of-pipe controls

  • Numerous Combined Sewer Overflow (CSO) storage tanks, treatment facilities, or stormwater quality control ponds are undergoing environmental assessment in order to identify and prioritize the opportunities.
  • The City is researching new wastewater treatment technologies in collaboration with the National Water Research Institute, Environment Canada and the Ministry of the Environment (MOE):
    • North Toronto High Rate Treatment Facility and the Etobicoke Stormwater Pilot-Scale High-Rate Treatment projects: two pilot projects underway to assess new high-rate treatment technologies
    • Scarborough Terraview Filtration Technology project: an underground sand filtration system feasibility study. Has suffered from large-volume bypasses, but research is ongoing.
    • Scarborough Dunker's Flow Balance System: a storage and treatment facility constructed on the lake using a series of plastic curtains suspended from floating pontoons, to create treatment cells. It is a very low-cost facility, but some of the wetland vegetation in the cells was killed by geese and carp. Research is ongoing.


  • Monitoring pollution levels at outfalls and beaches
  • Regular assessment of progress, with major status reports every 5 years

Research Analysis

Analysis of this case study leads to the following observations:

  1. Developers, while unlikely to incur extra costs voluntarily, can be persuaded to take on extra costs provided they and their competitors are given clear guidance and all are treated equally.
  2. A soft engineering approach has potential benefits for ecology and aesthetic landscape concerns. Infiltration areas can be designed to maximise value for wildlife and provide an attractive park like location.
  3. Sustainable drainage is not always entirely compatible with all topographies and geotechnical conditions.
  4. Retrofitting sustainable infrastructure is significantly harder to undertake than implementing such policies in new development. However in already developed areas, the Toronto case study provides many examples of possible approaches.
  5. A complete waste water management strategy is likely to require both large-scale projects (ie upgraded storage and treament facilities) and small-scale projects, such as public education and support for downspout disconnection.

Outstanding Questions

  1. Using open lagoons and retention ponds would provide valuable additional benefits for wildlife and aesthetic quality within the landscape – how would a municipality be able to offset some of the maintenance costs, liabilities and concerns over West Nile virus? Note that Toronto Water and Wastewater Services, in collaboration with Toronto Public Health, is conducting a number of pilot projects to investigate alternative, non-chemical methods to control mosquito larvae in catch basins. These include flushing, vacuuming, drilling drainage holes, filter cloths, ultrasound and steam. Further information can be found in this report.
  2. Public concern over water pollution is heightened in Toronto due to recreational use of its rivers and lake, and due to its drinking water being drawn from the lake. How can this same motivation be developed in cities without these same driving factors?

References and Footnotes

  1. CH2MHill, 2002, City of Chilliwack: Policy and Design Criteria Manual for Surface Water Management
  2. Stephens, K, Graham, P, Reid, D, undated, Stormwater Planning: A Guidebook for British Columbia, BC Ministry of Water Land and Air Pollution
  3. Toronto’s Water Pollution Solution… Going for the flow
  4. City of Toronto, (2003). List of CSO/Stormwater Control Alternatives (Blue Book). 
  5. City of Toronto, (2003b). Toronto’s Water Pollution Solution… The plan behind our plan
  6. City of Toronto, (2006). 2006 City Budget.  
  7. City of Toronto, (2006b). Wet Weather Flow Master Plan Implementation Report 2004-2005.
  8. City of Toronto, (2005). Operating & Capital Budget Summary.
  9. International Joint Commission, (1978). The Great Lakes Water Quality Agreement.
  10. Government of British Columbia, Ministry of Environment, Environmental Protection Division, (2005).  Stormwater Planning:  A Guidebook for British Columbia.


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Tax Break/Incentive

by Ryan Puhlmann - Friday, 2 March 2007, 09:59 AM

Anther point that caught my eye in the case study related to Toronto and the challenges faced under “what worked’ and “Financial Costs”. There was discussion on the free, voluntary downspout disconnection and despite its popularity, it would still take along time to reach the target of %40. The simply reality for many is that positive changes can come about however it typically is constrained by the physical costs of implementation. It is clear the our governments don’t want to incent or invite these opportunities as we have no systems in place, from a tax standpoint that support these changes. I complement the City Council in Toronto for recognizing the importance and the potential to make these changes mandatory, however the government should “have the back” of its people to make these changes. While a common argument, what about tax breaks for these changes?, we have some of these related to energy improvements. While challenges are greater in older communities do to structures and infrastructure of municipal systems, these are the areas that we can also lose site of.
Does anyone have any thoughts on the challenges or potential to lobey in these areas.

Re: Sustainability Synopsis?

by Heidi McGregor - Friday, 2 March 2007, 10:25 AM

Great synop. Very well said.
Social challenges need to be acknowledged. Vision, and systems thinking incorporating cultural viewpoints need to be considered in policy development, implementation and monitoring.
Community ownership provides a strong base to all programs.

Sustainability Synopsis?

by Ryan Puhlmann - Friday, 2 March 2007, 10:15 AM

From case study, and the already comments presented I have a sense that we are challenged significantly by regulatory systems. While policies and guidance is partially in place, we do very little to verify our success/failures, we offer little evolutionary knowledge to incite change, and we do not have Federal buy in through taxation benefits or the like. In all these case studies, we clearly see the power behind the socially responsible people and these changes are occurring on a small to medium level. We need to celebrate these small victories. Education is part of the solution, but celebrating our social capital and social will needs to become a bigger part of the picture. We have an understanding clearly of the environmental pros/cons, and the economic benefits, but the social is slow in the race,, like the turtle,, will it gain speed to win the race?

Re: Water Runoff

by Heidi McGregor - Friday, 2 March 2007, 10:05 AM

Good observation Jan,
Communities are attracted to build on floodplains, waterfront property continues to become more and more condensed. How do we balance cultural, social desire with watershed management?
By-laws on the proximity of building to riparian areas will take a precautionary approach instead of reactionary. Building permits encouraging water conservation and water recycling techniques will reduce the risk of flooding. Likewise, replacement of old pipes prior to construction could be required through by-laws.

Water Runoff

by Jan Quinlan - Friday, 2 March 2007, 09:40 AM

Heidi good points,
Rapid snow melt is a real problem in Calgary and leads to problems. People need to realize the risk involved in living in the areas where they choose. Some people in live in a an area called "High River", and then they are surprised that the beautiful river in their backyard has overflowed their basement...

Re: French drains

by Heidi McGregor - Friday, 2 March 2007, 09:25 AM

Great point Neil, Regional limitations are important. For example in Chilliwack the initial application of the policy on hill slopes was rejected as the infiltration of water into the slope is contrary to geotechnical safety considerations. In this case a policy of water retention not infiltration was used. Water needed to be released into water courses, or pipes down slope and infiltrated elsewhere (stormwater site).
Mountainous communities have additional limitations such as infrastructure hazards, and erosion. Flooding basements is a big concern to residents in with a rapid snow melt and high snow pack.

Re: Sustainable Development

by Ryan Puhlmann - Friday, 2 March 2007, 09:40 AM

Good points Jan:
Okotoks - Excellent point, the sleeply little community south of Calgary, but with the heart of a sustainability lion.
To answer to your immediate question, Okotoks does have a water management plan. It can be found at the following link.
The “Water Management Task Team has developed a 2005 Water Management Plan to ensure that Okotoks can meet the needs of residential, commercial and institutional water users now and in the future”

Sustainable Development

by Jan Quinlan - Friday, 2 March 2007, 09:29 AM

All these points really tie together nicely and lead to the obvious...everything be it water, soil, communities and people that live in them are connected and there needs to be long term planning. Okotokos, a small city south of Calgary that has a really progressive plan (any plan these days seems to be progressive - there seems to be so much reactive development) it has produced a strategy to limit growth of the city to 30,000 based on water. I wonder if they have also developed a SWM system


by Heather Beresford - Friday, 2 March 2007, 10:06 AM

And another thing....we're saying monitoring is important, and it is. But was there any baseline monitoring data beforehand against which to measure?

Re: SWM Monitoring and Assement - Validation the next frontier!

by Heidi McGregor - Friday, 2 March 2007, 09:35 AM

Great point Ryan.
The importance of monitoring is essential to the success of the program. Monitoring both the water quality and water levels provide measures of the effectiveness of the program.
Monitoring the implementation of the policy is critical too. The findings to the monitoring need to be reported in such a way to be applicable to operational changes such as combined versus separte storm and waste water systems. Effective public reporting involving electronic distribution of results and long term success and shortcomings of the program. Television ads, community posts are also good avenues for communication.

Natural Spaces

by Heather Beresford - Friday, 2 March 2007, 09:57 AM

Yes, natural spaces in urban areas are important for so many reasons beyond ecosystem health. It's good for people too! And, from a bottom line approach, more studies are showing that real estate near or adjacent to natural areas (ponds, streams, forests) can sell for a higher price. To make the leap to stormwater management, ponds and clean water are a selling feature.
See Curran, D. (2001). Economic Benefits of Natural Green Space Protection. Retrieved from

Re: SWM Monitoring and Assement - Validation the next frontier!

by Karen Larson - Friday, 2 March 2007, 09:33 AM

Ryan this is an excellent point the lack of monitoring and maintenance is one of the reasons that Public Health is against the use of retention ponds. I think prior to installation the contractor or new development should have long term commitments to monitoring and maintenance, be it the "new community". Perhaps we should have local governance systems to monitor these thing. We need to have natural spaces in our cities. In my community it would be easy to have volunteers monitor these features.

Re: SWM Monitoring and Assement

by Heidi McGregor - Friday, 2 March 2007, 10:18 AM

Good points Heather. Stormwater management plans are good mechanisms to outline a long term plan for management.
Strong policy goals are the foundation of this plan. Chilliwack has some stong policy goals. The long term implementaiton of these flows is the next challenge.
The case study outlines some beneficial Chilliwack policy,
"all new development must restrict flows from the subdivision or development to pre-development volumes.”
The goal of the current policy is to:
“ implement integrated stormwater management that maintains or restores the water balance and water quality characteristics of a healthy watershed, manages flooding and geotechnical risks to protect life and property, and improves fish habitat values overtime .”

SWM Monitoring and Assement

by Heather Beresford - Friday, 2 March 2007, 09:26 AM

I was also concerned when I read that there was no monitoring of the stormwater management features in Chilliwack. How can they be sure that they are reaching their targets? Another indication that a community needs to do the planning, but just as importantly, needs to commit the resources to implementing and monitoring the plan.

Re: Sustainable Cities

by Heather Beresford - Friday, 2 March 2007, 10:21 AM

Planning from a water-centric point of view leaves the required green infrastructure (streams, riparian areas) in place that can keep functioning after development. Municipalities are slowly realizing that keeping streams and their riparian areas intact can be a big savings in infrastructure costs. Combining that with low impact development which results in little pre- and post-hydrology change means that the aquatic areas can act as the big sponges for rainwater that they are, and slowly release the water to the stream which minimizes flooding and improves water quality. Developing like this means that the developer/municipality doesn't have to build so much hard stormwater infrastructure. It's being done in Victoria, Metchosin and other areas. Then those green areas also serve as natural refuge areas for people to recharge their batteries and connect to nature.

Sustainable Cities

by Karen Larson - Friday, 2 March 2007, 10:12 AM

I think we need to have built in incentives to create “green developments” for example zero taxes for green development. I envision these communities with lots of green spaces. Storm water could be managed by leaving as much of the natural vegetation as possible, with swales, roof top gardens. Best Management Practises – and integrated management is required. Smart cities with long term sustainability plans. I am tired of seeing forests on Vancouver Island being mowed down to make way for monster homes with no green spaces. We have to think in terms of 100 - 500 years instead of 10 years. I also believe the community we want to live in we create, we, the community, can force developments to be green!.

Re: What can other communities do

by Neil Hughes - Friday, 2 March 2007, 10:21 AM

From what I have read in all your postings and elsewhere, it seems we have the methods and the technology to make a huge difference in our new developments and even in existing cities. It is going to take all the things you have mentioned; planning and enforcement, dedicated staff, money and community involvement. That should not be a problem!!
My fear is the most likely way to create change is by consumers demanding it of municipalities and developers and this will not happen until education has completed its job.

Re: What can work in cities

by Jan Quinlan - Friday, 2 March 2007, 09:59 AM

It just requires planning and a community that demands planning before accepting a building/business into their area. How powerful Karen's Walmart example is...I'm sure they have a million different store plans and they always produce the cheapest one to the community first, when they encounter resistence, they go to "green plan B".
When I build a house, I won't get the concrete truck to pour my driveway without some thought before hand. I think we just get stuck because it is always the way we've been doing it. Its common and simple.

Re: What can work in cities

by Heidi McGregor - Friday, 2 March 2007, 09:45 AM

I agree Neil,
Parking lots are a poor reason for concrete carpeting city cores. Creative techniques such as grided parking areas with a combination of vegetation and checked concreate premit infiltration of these areas.
More to come on this.

Re: What can work in cities

by Heidi McGregor - Friday, 2 March 2007, 09:54 AM

Inspiring example karen,
It's great that the public united on this issue. It also shows how change can really happen with persistance, ingenuity, and community drive.

Re: What can work in cities

by Karen Larson - Friday, 2 March 2007, 10:04 AM

Niel Wal Mart was trying to get into our community and wanted to develop right on the estuary. There was a massive community uproar due to the potential loss of trees and effects of storm water runnoff on the estuary. Wal Mart came back with a green parking lot design. It was amazing, with lots of decidious trees and green spaces. Our community turned down their proposal anyways but I think it is interesting what we as a community could make the developers do. Demandingg green parking lot designs should be apart of our community plans. It is amazing how much power the people really do have- we need to legislate at local levels more green developments.

What can work in cities

by Neil Hughes - Friday, 2 March 2007, 09:32 AM

Within existing urban areas where there is little space for new drainage structures there is still the option for new concepts such as green roofs and “greening” of large tarmac / concrete areas. Replacing the impervious rooftops of large flat topped buildings with a green roof can have a large difference upon the retention of heavy rainfall, slowing up the flow to sewer systems. Apparently most studies show that there is 70-100% drainage off urban, impervious surfaces which compares to only about 5% on a natural vegetation surface whereas a green roof structure will reduce the run off considerably. According to the Healthy Cities Green roof web page a green roof can reduce run off to 10-30% in the summer and 65-70% in winter. The benefit through the winter is that the timing of the flow is slowed, with some data suggesting at least a three hour delay in the beginning of volume increases.

My big beef is with parking lots. massive expanses of concrete with occassionally a little flower bed in the middle. The BC stormwater guide (MoE) shows excellent examples of parking lot runoff designs but i have never seen such a thing. In Chilliwack there are huge areas of parking lots that I have never seen even half full and therefor have massive opportunity for "greening". They bake in the summer and flood in the winter. WHat they really need is large deciduous trees to provide shade and photosythesis capacity. But most towns spend all their time pruning and snipping to keep the trees small. I think there is lots more opportunities to plant and grow trees in cities.

SWM Monitoring and Assement - Validation the next frontier!

by Karen Larson - Friday, 2 March 2007, 09:09 AM

As noted in the Case Study, in Chilliwack, it was noted that “no monitoring has taken place”. Through further discussions with our municipal engineers in my department (Alberta Environment), I have noted that this is a reality. It is normally assumed that our provincial/municipal legislation works implicitly however we have little to no data verifying storm water management success. As we have discussed, the importance of integrating natural systems into our communities and/or emulating natural systems in our designs, as opposed to solely “colder” engineering designs, systems in many instances perform better, they have longer term cost savings, and they are socially recognized (e.g. natural wetland features – in some cases tied into community parks). From a social perspective, getting back in touch with our natural systems creates harmony and social value within a community. I would suggest that provincial or municipal funding/granting might be able to create volunteer programs to monitor these features. For the past 2years, I have participated in a program known as Alberta Water Quality Awareness Days, a “province-wide program focused on increasing people’s awareness and understanding of water quality and watershed health, through hands-on water quality testing.” This program is rising significantly since its conception 2005, and either through this program or the creation of a similar program, perhaps we could solve these very problems. Based on a priority (of known areas) or through random provincial/communities assessment, the program could validate the success of these SWM systems.

Re: French drains

by Karen Larson - Friday, 2 March 2007, 09:09 AM

Yes Jan awesome point - it seems we have terrible planning - there are poor management plans in place - short term gains for developer wins. We certainly need to work towards having sustainable planning.

Re: French drains

by Jan Quinlan - Friday, 2 March 2007, 09:07 AM

Neil, good point.
As a soil scientist I find it sad that housing developments are being developed on some of the most fertile ag. land. Considerations like this should be incorporated into development plans and although this is not directly related to SWM, lithology and water infiltration/stability is an important consideration. I wonder if these are important considerations in a development/Water management scheme or if it is all about location, location, location.

Re: French drains

by Karen Larson - Friday, 2 March 2007, 09:06 AM

What other ways can we prevent the need for stormwater retention pools? I find it great that city aforestation and green roof strategies, green buildings and cities are growing in popularity - I think any new development should be green and reduce the need for stormwater retention devices/

French Drains

by Neil Hughes - Friday, 2 March 2007, 09:00 AM

This is clearly a good point Heidi, but it brings up the questions of geographic region and the soil profiles in the area. The Chilliwack area has some of the best farm land in BC and is the result of the Fraser river depositing fine sediments over long time periods resulting in fine textured silts and cleys within a matrix of sands and gravels. This creates some areas withi impeded drainage where the use of french drains will be difficult. On the whole, coastal BC has lots of coarse textured glacial soils that would be very suitable for these kinds of open drainage systems.

Budget & Commitment

by Heather Beresford - Friday, 2 March 2007, 09:15 AM

Yes, Toronto seems to be really serious about tackling this problem by putting huge financial resources toward it. Chilliwack was chosen as a case study to try out the province’s new Stormwater Management Guidebook, and it got substantial funding from the province. I know that Chilliwack’s former head of the engineering department was a very strong leader in stormwater management and was very committed to the project. Now that Dipak has retired, that leadership is gone. It doesn’t seem that Chilliwack council or administration is committed either as there is no budget assigned to stormwater and no position either. It’s being managed off the corner of a desk. Toronto has created a specific position to manage the plan and dedicated a large budget – this is more likely to give long term success.

Re: Case Study West Nile

by Jan Quinlan - Friday, 2 March 2007, 08:59 AM

Thanks Jan.
The french drain would not be feasible in the downtown city center such as Toronto. But it does outweigh some of the negatives within common city stormwater management systems. For example:
A negative to stormwater management plans is the cost:
For example Chilliwack
The initial budget for the policy formulation and the development of design criteria ran to approximately $700,000. Likewise, The cost of Toronto's 25-year Wet Weather Flow Management Plan is estimated at $40,000,000 per year

Re: Case Study West Nile

by Jan Quinlan - Friday, 2 March 2007, 08:59 AM

Good point Heidi,
I was thinking that in an established area it may be difficult to install a french drain system...are there any other drawbacks of such a strategy

Re: Case Study West Nile

by Heidi McGregor - Friday, 2 March 2007, 08:52 AM

You bring forward good points on the risks of standing water.
The web site on stormwater brings up a good technique to avoid pooling. By installing ‘French Drains’ in a grass along the road side pooling will be reduced. The technique is a simple. A trench filled with gravel that allows water to drain away from the surface quickly but allows it to infiltrate into the subsurface rather than in to a drainage system.

Best Management Practices and BMP's

by Karen Larson - Friday, 2 March 2007, 09:13 AM

I agree Heather it is amazing where we can find standing water can be found in the back yard.Viriginia Recommends the following BMP's in designing to avoid mosquitoe breeding.
Reduce the need for stormwater management facilities. Design sites to:preserve natural drainage and natural treatment systems to reduce the need for additional structural stormwater management facilities (Low impact developmetnt). Better site design reduces the amount of stormwater runoff,provides for natural on-site control of runoff, and thereby reduces the number of structural measures needed (Virginia Government, 2004).
3. Improve permanent pool designs. Minimize shallow depths (i.e > 1 ft), increase pond circulation – continous water flow needed to prevent stagnation and vegetation growth.
Select stormwater management measures based on site -specific conditions. Site conditions, such as soils, topography, depth to rock, depth of seasonal high groundwater table, and Karst, significantly affect the performance of stormwater management facilities. Designs that take into account the site conditions will improve drainage and limit the occurrence of stagnant water.
For temporary water impoundments . Some stormwater management measures, such as dry ponds and man-made wetlands, pond water for an extended period. These facilities must drain the water completely within 30 hours of the storm event. The bottoms of the ponds must have positive drainage and be free of depressions. Avoid the placement of dry ponds and underground structures in areas where they are likely to remain wet (i.e., high water tables). Ensure that pond bottoms have a low-flow channel and a minimum of 1 to 2% bottom slope to prevent scour and stagnation.
Take care in the design of storm sewer systems. The sheltered environment inside storm drains can be ideal for mosquito breeding. Design and construct pipes at a rate of flow that flushes the system of sediment and prevents water backing up in the pipe (an acceptable minimum slope is 2%, as site conditions allows). (
Require “as -builts”. As-builts are survey drawings of stormwater management facilities after construction and provide sufficient information to demonstrate that the facility as constructed conforms to all specifications and requirements of the approved design plan. As-builts provide assurance that stormwater management facilities are effectively minimizing mosquito propagation.
Require and comply with a written maintenance

Re: Case Study West Nile

by Heather Beresford - Friday, 2 March 2007, 08:44 AM

In Whistler, we've been monitoring the mosquito populations for 3 years in anticipation of West Nile virus (WNv) arriving in BC. We've found that yes, we do have mosquito species that are at the highest likelihood of transmitting. At the same time, we are developing stormwater management plans and building developments that include retention ponds. Our understanding is that a functioning pond system with bats, birds etc. that eat bugs including mosquitos is no higher threat than a natural pond. We have so many natural wetlands and ponds, many in the heart of residential neighbourhoods, that the increased risk from stormwater retention ponds is considered negligible. We've located more of the high risk mosquito species in stormwater basins than in open ponds around the valley. To reduce risks around homes, there is more to be gained by having people empty standing water from tires, bird baths, kids pools, etc. that are on their property.

Reduce the need for storm water retention basins

by Karen Larson - Friday, 2 March 2007, 09:04 AM

Yes Integrated Management Plans including education, and BMP's. I think that retention Ponds in cities can work if properly designed keep the vegetation down, keep the water moving and use biological controls.
What other ways can we prevent the need for these facilities? I find it great that city aforestation and green roof strategies, green buildings and cities are growing in popularity - I think any new development should be green and reduce the need for stormwater retention devices/

Re: Case Study West Nile

by Ryan Puhlmann - Friday, 2 March 2007, 08:50 AM

I found to mention that in ALberta we have a program called "Fight the Bite"
I find that we are acceptable of the broad use of insecticides (socially acceptable really?) however we fail to make the connection between this and mosquito resistance development. Perhaps we have exaserbated the program, by creating to many stagnant SWM features, if we explore further options such as flowing systems, vegetative control measures and personal protective measures, these all seem reasonable.

Re: Case Study West Nile

by Ryan Puhlmann - Friday, 2 March 2007, 08:40 AM

I appreciate the information you have provided and we could discuss the development of a best management plan.
I know from experiences in AB that despite testing well over a 1100 locations, the occurance of West Nile has only been found in something like 1%.
The benefits of natural wetlands or other stormwater management features have numerous other benefits that outweigh (in my opinion) a mass hysteria about West Nile virus. Further, what about all the other natural waterbodies, and wetlands across our provinces,, this seems to defy logic.
Through conversation elsewhere I believe there was a legal case where the govt/municipality was sued, but this should not be happening.
Perhaps we should consider establishment of SWM features in those areas with no past histories of west nile, or we try broad educational programs that create awareness on westnile virus.

Re: Public Education

Neil Hughes - Friday, 2 March 2007, 09:22 AM

The comment on the down spout disconnection brought up the comment from a colleague whose mother has had her downspout disconnected and now her yard is flooded much of the time. I guess this is a point it brings us down the discussion on soil textures, if it is permiable this is a good idea but maybe not in the areas with cley type soils.

Public Education

by Heather Beresford - Friday, 2 March 2007, 09:01 AM

The public education aspect is very important. Toronto's Wet Weather Flow plan is a really well rounded strategy and recognizes that they have to get the public onside especially to move forward on retrofitting or making improvements on individual properties. Many people still don't understand that stormdrains are connected to streams so it's important to get the message out there. Chilliwack has taken a different tact and focused on the development guidelines/regulations with no public education component. Perhaps they're tackling that through a different program that's not mentioned in the case study. We really need to get the population as a whole to understand that our streets are directly connected to streams.
On a tangent, the downspout disconnection program is currently voluntary and making some headway but it would take 22 years to disconnect all homes. Currently, Toronto is debating making it mandatory but only offering a $300 rebate when they know the average cost is $1100. That's not much of an incentive. If they had the money budgeted over 22 years, move those funds forward, make it mandatory and keep paying for it.

Re: Case Study West Nile

by Jan Quinlan - Friday, 2 March 2007, 09:01 AM

You bring up some good points Heidi...
do you think there are also negative aspects?

Permeable driveways

by Heather Beresford - Friday, 2 March 2007, 09:22 AM

Those driveways work great - my friends have one. It's funny to see them mowing their driveway! To put those into high traffic areas, especially in snow country, is a little more difficult. Gravel fills them and reduces their efficiency, but some places are putting regular pavement in the main traffic lanes and permeable pavement in the stalls. There are lots of opportunities. Plus combined with open swales in the parking lots to capture the runoff can go a long way to minimizing stormwater.

Washing cars in driveways etc

by Neil Hughes - Friday, 2 March 2007, 09:08 AM

While looking for green roofing things yesterdeay I saw this picture of a driveway that was just a lattice of concrete with grass in between and apparently it works extremely well at increasing infiltration into the sub soil. This must be a concept that can be expanded to other situations like car parks. What if the actual driving surface was paved but the parking spots were made of this lattice material? I have more to say on car parks is this the place to say it?

Re: Case Study West Nile

by Jan Quinlan - Friday, 2 March 2007, 08:53 AM

I'm a big supporter of the public education programs this is a very successful approach for SWM. How many of us know where/how the storm water in our towns and cities goes and how it is delt with.
In Calgary, there is no storm water treatment and there is a city bylaw to prevent citizen's from washing their cars on the drive way, unfortunately, on a nice day you don't need to look too hard to find people suddings up the Bemer in the driveway. I just don't think people realize that what they are doing goes directly to the river.
Toronto had some really good adds promoting public education. This is a critical point to SWM.

Re: Case Study West Nile

by Neil Hughes - Friday, 2 March 2007, 08:52 AM

What has worked in Chilliwack
Within the Chilliwack area it seems that the data from the trial subdivisions is working adequately at this time. This suggests that we currently have the knowledge and the technology to manage stormwater in many situations, what may be lacking is the
commitment from municipalities and Regional Districts to implement it. Legislation / byelaws requiring the use of French drains, wider vegetated verges, retention ponds and clean water collection systems may be necessary. Obviously this will depend on the situation, with Chilliwack finding that steeper slopes are not conducive to infiltration. Another thought in that direction though is better planning of new developments, maybe we should be keeping off the sites which have stability problems to the extent we can't manage the water in a sustainable manner. Recent disasters in Vancouver with houses sliding down hillsides are evidence that we have pushed limits too far already.

Re: Case Study West Nile

by Heidi McGregor - Friday, 2 March 2007, 08:44 AM

I agree Jan. Education on the risk of west nile in stormwater holding mechanisms such as ponds, and water barrels is important.
West nile prevention and education plans could be incorporated into the 25 year management plan. Here are some insights on Toronto's iniatives through a long term sustainable stormwater management plan:
Community ownership on wastewater issues takes a systesm approach to incoporate active participation at a watershed scale. Toronto incorporates a number of effective tools to stormwater management. These include:
• a 25 year water pollution plan for longterm management. Ideally a sustainable management plan should be for a 100 years. The 25 years is a good start.
• The replacement of aging combined sewers with separate storm and sanitary sewers at required intervals. Faulty systems can cause some sewer pipes to back flow in sections of separate sewer lines in wet weather events polluting water ways.

Re: Case Study West Nile

by Karen Larson - Friday, 2 March 2007, 08:42 AM

West Nile encephalitis and West Nile meningitis are forms of severe disease that affect a person’s nervous system. Encephalitis refers to an inflammation of the brain, meningitis is an inflammation of the membrane around the brain and the spinal cord.
Click here for further explanation of WN meningitis and/or encephalitis.
West Nile fever refers to typically less severe cases that show no evidence of neuroinvasion.
Yes Jan apparently only 1% of the population who get west nile will develop encephhalitus..
I think that there are many biological controls that we could use
Biological Controls:
There are biological controls that could be put in place such as:
- larvivorous fish, predaceous fish ( Gambusia) or natural species from our own areas to control mosquito larva, other biocontrol agents include the mosquito Toxorhynchites, predacious copepods, parasitic nematode Romanomermis, and the fungus Lagenidium giganteum . Biocontrol could be an important control…. As part of an integrated approach.
- Use of larvecides ie. Bacillus thuringenisis
- Making the water flow is often the simplest method of eliminating habitat where mosquitoes will lay eggs. Improving drainage, eliminating pools and cleaning clogged ditches can produce a very effective control of these potential vectors.

Re: Case Study West Nile

by Jan Quinlan - Friday, 2 March 2007, 08:39 AM

There are non chemical methods for mossy control (i.e. carnivourous plants) and public education programs are an effective mean for communicating to people. If I remember correctly, there are only certain times of the year when the risk is Calgary, we're told to cover up and wear bug replent if outside.
Isn't west nile also a disease that only rarely produces sever side effects?

Case Study West Nile

by Karen Larson - Friday, 2 March 2007, 08:35 AM

Public Health Authorities are against retention ponds due to the fear of west nile virus ...see the
US /Canadian Map of cases below. WHile BC has not had a case yet other provinces and US States certaintly have. What BMP could we put in place to allow retention ponds in our communities..

Canadian Map of Cases

Cases of Encaphalitus/Meningitus/Fever

Description of diseases


Stormwater management is an important issue for many urban environments, especially with climate change and the predicted increase in intensity of winter storms and extreme spring runnoff events. I was recently speaking with a city manager in regards to this winter's storms and how the stormwater systems could not handle the runnoff– i.e. in December in Victoria thousands of basements were flooding during an extreme rainfall event with sewage and stormwater etc.We need to install infrastructure that is capable of handling Tier A, B, and C events.

With climate change, stormwater management in coastal towns will become a larger issue and we should be planning towards sustainable infrastructures. One issue that Jan has brought up is the issue of dry ponds/retention ponds/wetlands. The City of Chilliwack and Toronto have banned retention ponds due to “fear” over vector borne illness ie. West nile virus, these retention ponds could become “breeding grounds” for mosquitoes. While BC has yet to find west nile virus in the mosquitoe, bird or human populations (BCCDC, 2006) we are expecting that one day it will be apon us. I wonder how we can use BMP and sign contractual agreements to prevent mosquitoe breeding from occuring.

There are definitely other types of storm water management practices available especially for the urban environments such as roof top/community gardens to preserve the aesthetics of the area, provide a source of organic produce for the residents and again increase the rainfall capture area which reduces the impact and need for runoff controls.

What are the challenges of new versus old?

I am trying to collect myself of sorts, and am trying to get back to my roots of positive comments. As the old saying goes, "Comment on the good before you criticize the bad". Further to this point, I appreciate the comments made on the old versus new, and while the points are correct, I believe we can’t rule out the numerous options that exist for older systems.

This case study clearly highlighted the aspect that “in Chilliwack, no private developer has used it to date (referencing the water balance approach), preferring to implement there own design solutions” (Storm Water Management – Case Study, pg 7). This does not mean that many creative solutions are not taking place.

In Sept, 2004, as a Board of Directors member of the Alberta Lake Management Society (ALMS), I was responsible for the financial/sponsorship collection related to our annual general meeting/conference, and this was a demanding yet crowning achievement for this society. Formerly established in 1991, as a non-profit society, ALMS seeks to provide “a link to individuals, local communities, educational institutions, governments and industry across Alberta who are interested in lake and watershed management” (ALMS, 2006) ( Traditionally, the society has focused on the small to medium grassroots community lakes/watersheds, however in 2004 (and with earlier planning) we sought to challenge the very nature of the organization and Alberta in general, in providing the very first “Low Impact Development (LID)” conference. The function was a record success (well over 200 people).

Related to my point above, the LID conference highlighted many of the successful integrations of storm water management in new and old jurisdictions (from BC to USA). Referencing the above link provides access to many of the presentations that reflected this. Specifically, to my argument above and my general question of “Challenges of New vs Old?”, I recalled a specific presentation of Denise Andrews with the City of Seattle, whereby she presented some wonderful scenarios employed at both new and old developments. From the environmental side, in an older retrofitted development, stormwater runoff volumes were reduced by %98 (Andrews, 2004). From the side of costing, in scenarios focusing on new stormwater management versus older traditional systems, the cost saving were impressive (e.g. $325K vs $425, and $285K vs $520). While not immediately available in the presentation or explicitly stated the social benefits obviously included: improved water quality, protection of aquatic biota, aesthetic appeal/property value, social pride, and potentially local job creation.

Hope this provides some context for other discussion and question formulation.

Inital Thoughts

I like the approach that Chilliwack it taking with concentrating on new developments. Retrofitting is incredibly difficult and the costs become prohibitive for the homeowners in an area. In a new development, it can be built into the selling price of the lot. It is true that geotechnical considerations must be made. In my neightbourhood (which I always seem to talk about - its really nice for a new suburbany sprawl area) has a series of "dry ponds" and a little stream that channel water from parts of the community when it rains excessively. The dry pond fills (not sure why it is called a dry pond) and then the water can slowly infiltrate. Most of the time the pond is dry and acts as a sort of park, so this is also a nice feature.
Calgary is also in the process of developing some constructed wetlands, I'll get more information on this as it seems as this seems to be another progressive way to deal with wastes.