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→Water Table
If an underdrain is used, then an elevation difference of 1 to 1.5 m is needed between the inverts of the inlet and the downstream storm sewer.
If an underdrain is used, then an elevation difference of 1 to 1.5 m is needed between the inverts of the inlet and the downstream storm sewer.
===Water Table===
===Water Table===
Maintaining a separation of 1 m between the elevations of the bottom of the practice and the seasonally high water table, or top of bedrock, is recommended. Lesser or greater values may be considered based on [[groundwater]] mounding analysis.
Maintaining a separation of 1 m between the elevations of the bottom of the practice and the seasonally high water table, or top of bedrock, is recommended. Lesser or greater values may be considered based on [[groundwater |groundwater mounding analysis]].
===Pollution Hot Spot Runoff===
===Pollution Hot Spot Runoff===
To prevent groundwater contamination, runoff from pollution hot spots should not be treated by bioretention facilities designed for full or partial infiltration. Filtration only facilities (with an impermeable liner) can be used.
To prevent groundwater contamination, runoff from pollution hot spots should not be treated by bioretention facilities designed for full or partial infiltration. Filtration only facilities (with an impermeable liner) can be used.