Bioretention areas use plants and soil to slow and filter stormwater. Mimicking a natural process, bioretention areas allow for ponding of stormwater, filtering it through the planted area and through biotreatment soil media. The filtered water then percolates into the ground where it can replenish groundwater. Where site conditions don’t allow for this infiltration, a perforated underdrain sends the treated water to the storm drain system.