Best Management Practices that infiltrate stormwater runoff into underlying soil include, but are not limited, to

  • infiltration basins,
  • infiltration trenches,
  • underground infiltration,
  • bioinfiltration,
  • permeable pavements, and
  • tree trenches and tree boxes.

These are discussed briefly below.

Infiltration basin

photo of an infiltration basin
Photo of an infiltration basin. Source: Clark County, Washington, with permission.
Applications Treatment capabilities3, 4, 5
Residential yes TSS High6
Commercial Yes TN Medium/high
Unltra-urban Limited1 TP Medium/high
Industrial Yes2 Chloride Low
Highway/road Limited Metals High
Recreational Yes Oils and grease High
Pathogens High
1 Due to a size restriction; 2 Unless the infiltration practice is located in an industrial area with exposed significant materials or from vehicle fuelling and maintenance areas. Infiltration BMPs are PROHIBITED in these areas; 3Underground infiltration systems will have different pollutant removal capabilities than what is provided in this table. These systems may have a wider application range, however, there is concern that they do not provide adequate treatment of the pollutants; 4 This is only for the portion of flow that enters the infiltration basin; by-passed runoff does not receive treatment; 5 Low = < 30%; Medium = 30-65%; High = 65 -100%); 6 Assumes adequate pre-treatment

An infiltration basin is a natural or constructed impoundment that captures, temporarily stores, and infiltrates a design volume of water.