| [[Bioretention]] treats stormwater by slowing it down, filtering it through soil and plant roots, soaking it into the ground and evaporating it back to the atmosphere. Runoff water is delivered to the practice through [[inlet]]s such as [[curb cuts]], [[Curb cuts: Gallery|spillways]] or other concrete structures, sheet flow from pavement edges, or [[pipes]] connected to [[Pretreatment|catchbasins]] or [[Downspout disconnection roof downspouts]]. The planting bed and side slopes are typically covered with a mixture of [[plants]], [[mulch]] and [[stone]]. Water in excess of its storage capacity overflows to another BMP or the municipal storm sewer. Filtered water is either infiltrated into the underlying soil to replenish groundwater, or collected by a [[Underdrain|sub-drain]] (i.e., underground perforated pipe) and discharged to the storm sewer system or another BMP. Depending on the permeability of the underlying soil or other constraints, it may be designed with no sub-drain for [[Bioretention: Full infiltration|full infiltration]], with a sub-drain for [[Bioretention: Partial infiltration|partial infiltration]], or with an impermeable liner and sub-drain for a [[Stormwater Tree Trenches|no infiltration practice]]. The sub-drain pipe may feature a flow restrictor (e.g., orifice cap or valve) for gradually releasing detained water and optimizing the amount drained by infiltration. Key components of bioretention practices for inspection and maintenance described further below. | | [[Bioretention]] treats stormwater by slowing it down, filtering it through soil and plant roots, soaking it into the ground and evaporating it back to the atmosphere. Runoff water is delivered to the practice through [[inlet]]s such as [[curb cuts]], [[Curb cuts: Gallery|spillways]] or other concrete structures, sheet flow from pavement edges, or [[pipes]] connected to [[Pretreatment|catchbasins]] or [[Downspout disconnection|roof downspouts]]. The planting bed and side slopes are typically covered with a mixture of [[plants]], [[mulch]] and [[stone]]. Water in excess of its storage capacity overflows to another BMP or the municipal storm sewer. Filtered water is either infiltrated into the underlying soil to replenish groundwater, or collected by a [[Underdrain|sub-drain]] (i.e., underground perforated pipe) and discharged to the storm sewer system or another BMP. Depending on the permeability of the underlying soil or other constraints, it may be designed with no sub-drain for [[Bioretention: Full infiltration|full infiltration]], with a sub-drain for [[Bioretention: Partial infiltration|partial infiltration]], or with an impermeable liner and sub-drain for a [[Stormwater Tree Trenches|no infiltration practice]]. The sub-drain pipe may feature a flow restrictor (e.g., orifice cap or valve) for gradually releasing detained water and optimizing the amount drained by infiltration. Key components of bioretention practices for inspection and maintenance described further below. |