Site considerations
From LID SWM Planning and Design Guide
(Redirected from LID site criteria and constraints)
| Installation type | Depth to high water or bedrock (m)[1] | Typical ratio of ImperviousA hard surface area (e.g., road, parking area or rooftop) that prevents or retards the infiltration of water into the soil. drainage areaThe total surface area upstream of a point on a stream that drains toward that point. Not to be confused with watershed. The drainage area may include one or more watersheds. to treatment facility area |
Native soilThe natural ground material characteristic of or existing by virtue of geographic origin. infiltration rateThe rate at which stormwater percolates into the subsoil measured in inches per hour. (mm/hr)[2] | Head (m)[3] | Space % [4] | Slope % [5] | Applicable in pollution hotspots [6] | Set backs | Karst[7] | Wellhead protection area[8] |
|---|---|---|---|---|---|---|---|---|---|---|
| Rain Barrel | Not applicable | 5 to 50 m2 | Not applicable | 1 | 0 | NA | Yes | None | Yes | None |
| Cistern | Not applicable | 1:1 | Not applicable | 0 | 0 | 0 | Yes | None | Yes | None |
| Roof downspout disconnection | Not applicable | 5 to 100 m2 | Amend if < 15 mm/hr | 0.5 | 5 to 20 | 1 to 5 | Yes | Building Foundation | Yes | None |
| SoakawayA pit into which liquids may flow and then percolate slowly into the subsoil.An excavated area lined with geotextile filter cloth and filled with clean granular stone or other void forming material, that receives runoff and allow it to infiltrate into the native soil; can also be referred to as infiltration galleries, French drains, dry wells or soakaway pits., infiltration trench or chamber | 1 | 5:1 to 20:1 | Not a constraint | 1 to 2 | 0 to 1 | <15 % | No | 4m- Building Foundation Underground Utilities, Trees, Drinking Water Wellhead Protection Areas |
No | 2 yr |
| Bioretention | 1 | 5:1 to 15:1 | Underdrain recommended if < 15 mm/hr |
1 to 2 | 5 to 10 | 0 to 2 | No (infiltrating); Yes (non-infiltrating) | 4m- Building Foundation Underground Utilities, Trees, Drinking Water Wellhead Protection Areas |
No (infiltrating); Yes (non-infiltrating) | 2 yr (infiltrating); None (non-infiltrating) |
| Stormwater planters | Not applicable | 5:1 | Not a constraint | 1 to 2 | 2 to 5 | 0 to 2 | No (infiltrating); Yes (non-infiltrating) | Building Foundation, Trees | No (infiltrating); Yes (non-infiltrating) | 2 Yr (infiltrating); None (non-infiltrating) |
| Vegetated filter strip | Not applicable | 5:1 | Amend if < 15 mm/hr | 0 to 1 | 15 to 20 | 1 to 5 | No | None | Yes | None |
| Permeable pavement | 1 | 1:1 to 1.2:1 | UnderdrainA perforated pipe used to assist the draining of soils. recommended if < 15 mm/hr |
0.5 to 1 | 0 | 1 to 5 | No (infiltrating); Yes (non-infiltrating) | 4m-Underground Utilities Drinking Water Wellhead Protection Areas |
No (infiltrating); Yes (non-infiltrating) | 2 Yr (infiltrating); None (non-infiltrating) |
| Enhanced grass swale (has checkdams) | Not applicable | 5:1 to 10:1 | Not applicable | 1 to 3 | 5 to 15 | 0.5 to 6 | No | 4m- Building Foundation Underground Utilities |
Yes | None |
| Dry swale (BioswaleLinear bioretention cell designed to convey, treat and attenuate stormwater runoff. The engineered filter media soil mixture and vegetation slows the runoff water to allow sedimentation, filtration through the root zone, evapotranspiration, and infiltration into the underlying native soil.) | 1 | 5:1 to 15:1 | UnderdrainA perforated pipe used to assist the draining of soils. recommended if < 15 mm/hr |
1 to 3 | 5 to 10 | 0.5 to 6 | No (infiltrating); 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 Yr (infiltrating); None (non-infiltrating) |
| Perforated pipe system | 1 | 5:1 to 10:1 | Not a constraint | 1 to 3 | 0 | < 15% | No | 4m- Building Foundation Underground Utilities, Trees, Drinking Water Wellhead Protection Areas |
No | 2 Yr |
- ↑ Minimum depth between the base of the facility and the elevation of the seasonally high water table or top of bedrock
- ↑ Infiltration rate estimates based on measurements of hydraulic conductivity under field saturated conditions at the proposed location and depth of the practice
- ↑ Vertical distance between the inlet and outlet of the LID practice
- ↑ Percent of open pervious land on the site that is required for the LID practice
- ↑ Slope at the LID practice location
- ↑ Suitable in pollution hot spots or runoff source areas where land uses or activities have the potential to generate highly contaminated runoff
- ↑ Suitability in areas of karst geologic formations
- ↑ | Drinking Water Source Protection wellhead protection area time of travel
