Wetland and Riparian Zone Protection. Wetlands and riparian areas are often continuums along rivers, streams, and coastal waters and are particularly sensitive to landscape changes and fragmentation. From the catch basins, runoff is conveyed to the other water quality BMPs. This pretreatment extends the life and performance of the other BMPs. Catch basins are used primarily as a pretreatment device for the removal of coarse grit, sand, and debris. Pollutant removal in an artificial media or natural soil profile occurs through filtration, absorption, and oxidation by soil microorganisms.Ĭatch Basins.
Infiltration generally improves water quality by allowing natural physical, chemical, and biological processes to remove pollutants. Infiltration controls are a general category of structural BMPs that maintain or enhance the ability of water to percolate through the soil profile. Water temperatures of surface runoff, released through underground outlets, may increase slightly because of longer exposure to warming surfaces during its impoundment. Where geologic conditions permit, the practice leads to increased loadings of dissolved substances toward groundwater. Dissolved substances, such as nitrates, may be removed from discharge to downstream areas because of the increased infiltration. Trap control efficiencies for sediment and total phosphorus transported by runoff may exceed 90% in silt loam soils. This feature traps and removes sediment and sediment-attached substances from runoff. Wet ponds are also effective in reducing peak discharges, downstream flooding, and stream bank erosion at the golf course.
The highest removal efficiencies are achieved in larger ponds at the golf course, where the ratio of basin volume to the volume of runoff from the average storm is greatest. Pollutant removal efficiencies of wet ponds vary based on the pollutant of concern and the size of the permanent pool. Secondary benefits include recreation, aesthetics, and wildlife habitat. Aquatic plants and biochemical processes within the ponds enhance the removal of nutrients, metals and other pollutants. Wet ponds at the golf course use a permanent water surface to achieve a high removal rate for sediment, nutrients, and metals. Wet ponds are one of the most effective structural BMPs for protecting water quality. These ponds are earthen embankments or a combination ridge and channel generally constructed across the slope and minor watercourses to form a sediment trap and water retention basin. Finally, higher intensity storms can be routed through water quality basins for proper flood control and flow attenuation. Gravel underdrains without an outlet can also provide a measure of infiltration and groundwater recharge where appropriate. The discharge system for basins can include a gravel underdrain layer with a small diameter perforated drainage pipe to slow dissipation of runoff over an extended period. Planting wetland species in the bottoms of these basins achieves additional quality control through biological filtering and uptake. These basins can be constructed by excavation or embankment (or both) to create a ponding area sufficient to handle the required water quality volumes. Water Quality Basins. These basins are designed to capture the “first flush” runoff and provide water quality treatment primarily through physical settling of sediment-based pollutants. Where possible, directing this drainage into vegetative areas for biological filtration or infiltration basins helps to control the potential loss of nutrients and pesticides from the golf course, rather than directly draining it into surface water. Subsurface drainage is also installed to control a water table or to interrupt subsurface seepage or flow. Subsurface Drainage. Subsurface drainage directs drainage water and can reduce runoff and leaching. These structures detain and filter water through plant material prior to discharge and can reduce runoff quantity as well as nutrient and pesticide discharge. Structural controls include water quality basins, infiltration basins, and catch basins to regulate or impound runoff.