Draft Details

Designation:W204
Source:CSA
Review start date:Apr 30, 2019
Review end date:Jun 30, 2019
Contact email:lynn.barber(at)csagroup.org
Draft Scope/Description:

Purpose and Scope

The purpose of this standard is to provide compliance criteria and guidance on the design of flood-resilient new residential communities as it relates to Greenfield development only.

In-Scope of the Standard

Building types

This standard is applicable to the following building types:

Detached homes;

Semi-detached homes;

Row houses (including stacked and back-to-back townhomes); and

Mixed-use residential development (residential, small commercial and institutional use).

Note: Garages (attached and detached) and non-habitable accessory buildings (e.g., porches, gazebos, etc.) located on the residential lots are considered in-scope of this standard.

 

Design Elements

The scope of the standard pertains to the following considerations:

Design for resilience to address extreme weather events and operational uncertainties;

Storm sewer system design (minor drainage system considerations);

Street design (major overland drainage system considerations);

Sanitary sewer design (wastewater drainage system considerations);

Wastewater pumping station design; and

Considerations for preservation of natural infrastructure and low impact development measures.

 

Flood Hazards

The types of flood hazards considered by this standard include:

Riverine flooding;

Overland flooding;

Storm and sanitary sewer surcharge;

Drainage system failures (e.g., inlet, ice and debris blockages); and

< > seepage.

Out of Scope for the Standard

Other types of development

This standard does not cover flood-resiliency considerations as they relate to existing development, infill, intensification or re-development.

 

Types of Flood Hazards

Types of flood hazard that are outside the scope of this standard include:

A sea level rise;

Storm surges;

Unique flood hazards (e.g., dam failures); and

Flood risk specific to alluvial fans.

 

Geographic Limitations

This standard includes requirements and recommendations expected to be relevant across Canada.  Its application may be insufficient in the areas with permafrost, such as Yukon, Northwest Territories and Nunavut, as well as in areas subject to coastal and lake flooding, where sea level rise and storm surges pose additional flood risk, not addressed by the standard.

Terminology

In this standard, “shall” is used to express a requirement, i.e., a provision that the user is obliged to satisfy in order to comply with the standard; “should” is used to express a recommendation or that which is advised but not required; and “may” is used to express an option or that which is permissible within the limits of the standard.

 

Notes accompanying clauses do not include requirements or alternative requirements; the purpose of a note accompanying a clause is to separate from the text explanatory or informative material.

 

Notes to tables and figures are considered part of the table or figure and may be written as requirements.

 

Annexes are designated normative (mandatory) or informative (non-mandatory) to define their application.

Requirements of Local Jurisdictions

This standard provides requirements and recommendations for the design of flood-resilient Greenfield community developments. In the application of this standard, it should be noted that local jurisdictions might have criteria or requirements beyond what is provided in this standard. The intent of this standard is to provide minimum acceptable criteria. In the event that a local jurisdiction requirement is more stringent than that required by this standard, the more stringent requirement shall take precedence over the requirement stipulated in this standard. It is the responsibility of the user of this standard to be aware of an discrepancies and to determine the manner in which it can be resolved.

Climate Uncertainty Consideration

This standard provides a dynamic approach to the design of flood-resilient new residential communities. This includes the use of data that anticipates future climate changes, including changes in the frequency of extreme rainfall events. Such data is currently the subject of intense research, but is not yet available with adequate confidence.  In the absence of such predictive climate data, the users of this standard should consider applying appropriate adjustments to current Intensity-Duration-Frequency (IDF) values to account for climate uncertainties. For information on the use and interpretation of IDF data see CSA PLUS 4013.

 

Note: a new edition of CSA PLUS 4013 is currently under development

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