Infiltration

From LID SWM Planning and Design Guide
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Infiltration of stormwater into underlying soils is one the Priority level 1. mechanisms to achieve MOECC Runoff Volume Control targets.

Infiltration is promoted through a number of LID BMPs:


Potential Constraints[edit]

  1. Shallow bedrock
  2. High groundwater or areas where increased infiltration will result in elevated groundwater levels, which can be demonstrated to damage critical utilities or private property.
  3. Swelling clays or unstable sub-soils
  4. Contaminated soils or sites with high risk of contamination from onsite activities
  5. Flood prone areas where the wastewater system is sensitive to groundwater conditions causing sewer backups, and where LID BMPs have been found to be ineffective.
  6. Areas where the ecology and natural hydrology are dependent upon surface water.
  7. Prohibitions and/or restriction per approved Source Protection Plans (see MOECC guidance).

Planning[edit]

Soil Infiltration Testing

Infiltration tests must be undertaken at the location, depth and with a head of water that replicates the proposed design.

Groundwater

The bottom of the infiltration BMP must ≥ 1 m vertically separated from the seasonally high water table, and underlying bedrock. This reduces the risk of contaminating groundwater and helps to ensure reliable infiltration rates throughout the year.