Stormwater

Stormwater Culvert, Armstrong

As stormwater runs off urban areas, it can gather pollutants such as oil, pesticides and other contaminants that can have an adverse effect downstream. The "non-point source" water pollution in stormwater runoff is the most common cause of poor water quality in urban lakes and streams.
 

The objective of traditional drainage planning is to prevent flooding by draining stormwater as quickly as possible from developed areas. This approach results in an increase in the volume and flow rate of surface runoff, causing excessive erosion and habitat degradation in the receiving streams. Urbanization has changed the natural hydrology of watersheds, resulting in channel instability, low summer flows, and altered stream morphology. The cumulative effects of these changes impacts the integrity and diversity of aquatic ecosystems.
 

Given the impacts of conventional stormwater management practices, protecting the health of urban watercourses clearly requires a different approach.
 

Integrated Stormwater Management

• rain from frequent small events be allowed to infiltrate the ground,
• runoff from heavy events should be retained and slowly released,
• runoff from extreme storms should be managed to prevent flooding.

Integrated stormwater management plans can be used to meet the stormwater component of a Liquid Waste Management Plan. Stormwater management objectives can be integrated into local government land use planning and decision-making by incorporating them into the vision and goals of the Official Community Plan.
 

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Stormwater Management Facilities

Victoria - Stormwater Rehabilitation System

Using design techniques that take advantage of ecological and hydrological processes allows communities to meet flood prevention objectives and preserve or enhance the health of aquatic and riparian ecosystems. The Greater Vancouver Regional District has developed Stormwater Source Control Design Guidelines to promote innovative designs that can be incorporated into new or existing developments such as:

• Absorbent Landscape (1.1 MB)
• Extensive Greenroof (956 KB)
• Infiltration Swale (1 MB)
• Pervious Paving (1.2 MB)
• Infiltration Trench (1 MB)
• Rain Garden (1.1 MB)

Funding for Stormwater Management

The Department's grant programs have funded such projects as:

• District of Lantzville Low Impact Development Model Bylaw
  • See Schedule D for Low Impact Development Guidelines for Surface Rainwater Management (1.66 MB)
• Water Balance Model for British Columbia
• Waterbucket.ca
• Millstream Watershed Management Plan (19 MB)
• Master Municipal Construction Document Association's Green Design Guidelines (490 KB)

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Stormwater Management Resources

• bylaws that limit impervious surfaces and encourage infiltration;
• alternative low impact subdivision bylaw standards;
• bylaws that prevent the release of contaminants into stormdrains;
• watercourse setback zoning bylaws; and,
• development permit areas that protect watercourses and floodplains.

Implementation of integrated stormwater management can be accelerated by applying the practices, designs and strategies contained in the following documents:

• Beyond the Guidebook: Context for Rainwater Management and Green Infrastructure in British Columbia
• Stormwater Planning: A Guidebook for British Columbia
• Tackling Non-Point Source Water Pollution in British Columbia: An Action Plan
• CRD Storm Sewer and Watercourse Bylaw, Codes of Practice and Best Management Practices (708 KB)
• Stormwater Best Management Practices Guide
• Green Design Guidelines (496 KB)
• Integrated Stormwater Management Plan template (12 MB)
• U.S. Environmental Protection Agency: Reducing Stormwater Costs through Low Impact Development (LID)