CSA W200:26

Description

Preface This is the second edition of CSA W200, Design and construction of bioretention systems and rain gardens . It supersedes both the previous edition published in 2018 and CSA W201, also published in 2018. The importance of proper stormwater management has become increasingly apparent in recent years, as Canada is experiencing increases in precipitation due to climate change, which causes greater instances of flooding. This Standard provides requirements and recommendations for the design and construction of bioretention systems and rain gardens intended for the management of urban stormwater runoff. The following are the major changes to this edition: a) addition of new specifications on the design and construction of rain gardens; and b) the amalgamation of CSA W200 and CSA W201 into one standard. CSA Group acknowledges that the development of this Standard was made possible, in part, by the financial support of Standards Council of Canada as part of the Standards to Support Resilience in Infrastructure Program, which promotes the development and update of standards and technical guidance to adapt infrastructure to climate change. This Standard was prepared by the Subcommittee on Design and Construction of Bioretention Systems and Rain Gardens, under the jurisdiction of the Technical Committee on Community Water — Drinking, Storm, and Waste, and the Strategic Steering Committee on Natural Resources, and has been formally approved by the Technical Committee. This Standard has been developed in compliance with Standards Council of Canada requirements for National Standards of Canada. It has been published as a National Standard of Canada by CSA Group. Scope 1.1 General This Standard provides requirements and recommendations for the design and construction of bioretention systems and rain gardens intended for the management of urban stormwater runoff. This Standard covers the following items: a) roles and responsibilities; b) design guidance; c) contract documentation; d) construction sequencing; e) erosion and sediment control for bioretention systems; f) construction documentation; g) material supply and handling; h) installation considerations; i) landscape materials and maintenance; j) construction warranty maintenance; and k) assumption protocols. Where this Standard conflicts with regulatory requirements, the regulatory requirements take precedence. 1.2 Users Potential users of this Standard include the following: a) technical practitioners — engineering design, planning, and other technical practitioners within and outside of government who play integral roles in design and construction; b) authority having jurisdiction staff — staff that construct, assume, and operate bioretention systems and rain gardens; c) non-governmental organizations — organizations that manage, promote, and implement sustainable stormwater programs and projects; and d) builders and developers — including improved stormwater management and climate resiliency into infrastructure design and construction. 1.3 Bioretention system features covered by this Standard The following types of bioretention systems are covered by this Standard: a) bioretention systems with an underdrain; b) bioretention systems without an underdrain; and c) biofilters (impermeable liner). 1.4 Rain garden features covered by this Standard Rain gardens covered by this Standard do not include an underdrain or an impermeable liner within their designs. Note: With proper provisions, rain gardens can be installed with liners if installed within required building setbacks. 1.5 Bioretention systems not covered by this Standard The following sub-types of bioretention systems are not covered by this Standard: a) tree trenches or pits; and b) soil cells. 1.6 Regional context The application of bioretention systems and rain gardens to provide stormwater management varies across the country due to climate, resources, and different jurisdictional requirements. Users of this Standard should consider the application of this Standard with respect to jurisdictional requirements and adopt or revise clauses as necessary. This Standard should not be considered a replacement for the requirements contained in any a) applicable federal or provincial/territorial statute; b) regulation, licence, or permit issued pursuant to an applicable statute; or c) contract that an owner has with a contractor. Bioretention systems and rain gardens are designed to meet or achieve design or performance criteria set by a local or regional authority or, in the absence of local criteria, should be designed in accordance with typical criteria outlined in this Standard. 1.7 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.