Difference between revisions of "Screening LID options"

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* public lands including parks, churches, or schools, see [[Link title]]
* public lands including parks, churches, or schools, see [[Link title]]
* commercial, industrial and multi-residential, see [[Site Conditions Commercial, Industrial, and Multi-Residential]]
* commercial, industrial and multi-residential, see [[Site Conditions Commercial, Industrial, and Multi-Residential]]
* residential, see [[Link title]]
* residential, see [[Site Conditions Residential]]


=== Define Design Criteria ===
=== Define Design Criteria ===

Revision as of 17:28, 15 September 2017

Process for selecting an individual or suite of LID Options[edit]

Process Diagram for Screening LID Options

The guidance found on this page is not intended be prohibitive of LID options, but rather to help reduce the number of LID options in the preliminary phases of design and alert the designer to LID opportunities unique to the site being assessed. When going through the process of screening LID options, it is important to have a larger contextual understanding of Integrated water management, Site design strategies, Siting and layout of development, and Link title.

Site Conditions[edit]

Complete definition of pre-development site conditions is essential prior to screening of

potential stormwater BMPs. The designer should prepare maps describing site

conditions to ensure that all environmental features and functions that need

consideration in accordance with provincial, municipal and conservation authority

development regulations are identified. This includes watercourses and small drainage

features, floodplains, important recharge areas, steep slopes, wetlands, natural heritage

conservation areas and significant wildlife habitats. In addition, information regarding

native soil types, infiltration capacity and depth to water table must be determined.


In retrofit scenarios, site conditions will vary and can be explicit with land use type such as road right of ways, parks, residential, industrial, commercial and/or institutional should be noted.

For additional information on site conditions to note for:

Define Design Criteria[edit]

A detailed description of the design criteria that need to be defined is provided in the

respective CVC and TRCA Stormwater Management Criteria documents. If outside jurisdictional

boundaries, criteria developed should have requirements to:

  • preserve groundwater and baseflow characteristics;
  • prevent undesirable and costly geomorphic changes in the watercourse;
  • prevent any increases in flood risk potential;
  • protect water quality; and ultimately,
  • maintain an appropriate diversity of aquatic life and opportunities for human uses

The design criteria required to protect, enhance or restore the environmental resources

can be grouped under the following five categories.

  • Flood Protection;
  • Water Quality;
  • Erosion Control;
  • Recharge; and
  • Natural Heritage Systems or green infrastructure


Screen Potential LID Options[edit]

A number of factors need to be considered when screening the suitability of a given

location within a development site for application of stormwater BMPs. Table 3.4.1

summarizes site constraints associated with some general types of structural LID

practices for stormwater management that should be considered. Further

information regarding constraints to the design of various end-of-pipe BMPs can be

found in the Ontario Ministry of the Environment Stormwater Management Planning and

Design Manual (2003). The use of LID BMPs should be considered first to meet the

design criteria before the use of end-of-pipe BMPs.


Structural Requirements or Site Constraints[edit]

Performance Requirements[edit]

Operations and Maintenance Requirements[edit]

Life Cycle Costing Requirements[edit]

Select LIDs (Conceptual Design)[edit]

In order to assess if the selected suite of BMPs effectively meet the design criteria

either computer models or simple spreadsheet models should be used. Model selection

will be based on the size and type of development. A wide range of simple to complex

computer models such as Visual OTTHYMO, SWMM, SWMMHYNO, HSP-F and

QUALHYMO are available.

Assess Effectiveness[edit]

Once the suite of best management practices have been selected and the models have

been run, a comparison of the results and the environmental design criteria can be

made. An iterative approach, which involves adjusting the size or adding/deleting BMPs

should be used until the environmental design criteria are met. The project can then

proceed to the detailed design stage.