schematic of groundwater mound
Schematic illustrating groundwater mounding beneath an infiltration BMP (Source: CDM Smith)

The localized groundwater surface may temporarily rise below an infiltration BMP, creating a condition termed groundwater mounding. Mounding can occur in areas where the volume of water entering the subsurface is greater than the soil is able to convey away (Susilo, 2009). Infiltration BMPs in particular have the potential to cause a groundwater mound, given the right subsurface conditions, because they direct the recharge to a specific area (Machusick and Traver, 2009). Figure 1.18 illustrates this concept.