Site considerations

From LID SWM Planning and Design Guide
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Installation type Depth to high water or bedrock (m)i Ratio of impervious drainage area to
permeable facility footprint area
Native soil infiltration rate (mm/hr)ii Head (m)iii Space %iv Slope %v Applicable in pollution hotspotsvi Set backs Karstvii Drinking Water Source Protection wellhead protection area time of travel
Rain barrels Not a constraint Not applicable Not a constraint 1 0 NA Yes None Yes None
Cisterns Not a constraint Not applicable Not a constraint 0 0 0 Yes None Yes None
Roof downspout disconnection Not a constraint 4:1 or less Decompaction if < 15 mm/hr 0.5 5 to 20 1 to 5 Yes Building Foundation Yes None
Infiltration trenches or Infiltration chambers 1 5:1 to 20:1 Not a constraint 1 to 2 0 to 1 <15 % Noix 4m- Building Foundation
Underground Utilities, Trees,
Drinking Water Wellhead
Protection Areas
No 2 year - WHPA-B
Bioretention 1 (infiltrating); Not a constraint (non-infiltrating) 5:1 to 15:1 Decompaction and underdrain recommended
if < 15 mm/hr (infiltrating)
1 to 2 5 to 10 0 to 2 No (infiltrating)ix; Yes (non-infiltrating) 4m- Building Foundation
Underground Utilities, Trees,
Drinking Water Wellhead
Protection Areas
No (infiltrating); Yes (non-infiltrating) 2 year - WHPA-B (infiltrating); None (non-infiltrating)
Stormwater planters Not a constraint 5:1 Not a constraint 1 to 2 2 to 5 0 to 2 No (infiltrating)ix; Yes (non-infiltrating) Building Foundation, Trees No (infiltrating); Yes (non-infiltrating) 2 year - WHPA-B (infiltrating); None (non-infiltrating)
Vegetated filter strips Not a constraint 4:1 or less Decompaction if < 15 mm/hr 0 to 1 15 to 20 1 to 5 Noix None Yes None
Permeable pavements 1 (infiltrating); Not applicable (non-infiltrating) 0 to 1:1 Underdrain recommended
if < 15 mm/hr (infiltrating)
0.5 to 1 0 1 to 5 No (infiltrating)ix; Yes (non-infiltrating) 4m-Underground Utilities
Drinking Water Wellhead
Protection Areas
No (infiltrating); Yes (non-infiltrating) 2 year - WHPA-B (infiltrating); None (non-infiltrating)
Enhanced swales (featuring check dams) 1 5:1 to 10:1 Decompaction if < 15 mm/hr 1 to 3 5 to 15 0.5 to 6 Noix 4m- Building Foundation
Underground Utilities
No 2 year - WHPA-B
Bioswales (Dry swales) 1 (infiltrating); Not applicable (non-infiltrating) 5:1 to 15:1 Decompaction and underdrain recommended
if < 15 mm/hr (infiltrating)
1 to 3 5 to 10 0.5 to 6 No (infiltrating)ix; Yes (non-infiltrating) 4m (3m if impermeable liner
is used) Building foundation,
Underground utilities,
Drinking Water Wellhead Protection Areas
No (infiltrating); Yes (non-infiltrating) 2 year - WHPA-B (infiltrating); None (non-infiltrating)
Exfiltration trenches 1 5:1 to 10:1 Not a constraint 1 to 3 0 < 15% Noix 4m- Building Foundation
Underground Utilities, Trees,
Drinking Water Wellhead
Protection Areas
No 2 year - WHPA-B
Stormwater tree trenches 1 5:1 to 15:1 Underdrain recommended
if < 15 mm/hr
1 to 2 5 to 10 0 to 2 No (infiltrating)ix; Yes (non-infiltrating) 4m- Building Foundation
Underground Utilities,
Drinking Water Wellhead
Protection Areas
No (infiltrating); Yes (non-infiltrating) 2 year - WHPA-B
Notes
i Minimum depth between the base of the facility and the elevation of the seasonally high water table or top of bedrock
ii Infiltration rate estimates based on measurements of hydraulic conductivity under field saturated conditions at the proposed location and depth of the practice
iii Vertical distance between the inlet and outlet of the LID practice
iv Percent of open pervious land on the site that is required for the LID practice
v Slope at the LID practice location
vi Suitable in pollution hot spots or runoff source areas where land uses or activities have the potential to generate highly contaminated runoff
vii Suitability in areas of karst geologic formations
viii Drinking Water Source Protection wellhead protection area time of travel
ix May be allowed under special circumstances and if appropriate mitigation actions are taken - please contact your local Source Protection Region (SPR) or Source Protection Area (SPA) for further information. You can find your associated SPR/SPA based on your location here and then visit their site here