Draft Details

2.1 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;

f) construction documentation;

g) material supply and handling;

h) installation considerations;

i) landscape materials and maintenance;

j construction warranty maintenance; and

k) assumption protocols.

2.2 Users

The intention if this standard is that responsible authorities can use this Standard for better planning, and design, policy making and decision-making with respect to these assets.

Potential users include:

a)    technical practitioners: Engineering design, planning, and other technical practitioners within and external to government play integral roles in design, and construction.

b)   Authority having jurisdiction staff: staff that construct, assume and/or operate bioretention systems and rain gardens.

c)    builders/developers: Builders and developers should factor improved stormwater management and climate resiliency into infrastructure design and construction.

2.3 Bioretention features covered by this Standard

The following types of bioretention systems are covered by this Standard:

a)    bioretention systems with an underdrain and without an underdrain; and

b)   biofilters (impermeable liner).

2.4  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.

2.5 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.

2.6 Regional Context

The application of bioretention systems and rain gardens to provide stormwater management varies across the country due to climatic, resource and different jurisdictional requirements. Users of this document will be required to consider the application of this standard with respect to their jurisdiction and adopt and/or revise the clauses as fits their requirements.

Users of this Standard are reminded that this Standard should not be considered a replacement for the requirements contained in any:

a)    applicable federal/territorial or provincial statute;

b)   regulation, license, or permit issued pursuant to an applicable statute; or

c)    contract that an owner has with a contractor.

Bioretention systems and Rain Gardens shall be designed to meet or achieve design or performance criteria set by a local or regional authority, or in the absence of local criteria, shall be designed in accordance with typical criteria outlined in this standard.

2.7 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.