Agenda - Council Work Session - 12/10/2024

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SECTION 6 APPENDIX Definitions Drainage structure — Catch basin (CB), flared end (FE), manhole (MH), outlet control structure (OCS), or structural pollution control device (SPCD). Catch basins and manholes may include a sump in the bottom to help remove sediment and debris from runoff before being discharged from the storm sewer system. Drainage pipe — Storm sewer or culvert pipe, typically composed of corrugated metal pipe (CMP), polyethylene (PE) pipe, or reinforced concrete pipe (RCP). Drainageway — Channel, ditch, filter strip, swale or other surface stormwater conveyance constructed to direct or convey stormwater runoff. Most drainageways are vegetated to maintain the structure, resist erosion, assist in decreasing runoff velocity, and promote infiltration and physical filtration. Some drainageways incorporate rock checks to further reduce erosion, sediment transport and runoff velocities. If problems are identified during inspections, a Work Order will be prepared in accordance with the following guidelines; • Remove sediment when it blocks the flow of stormwater. • Stabilize and re -seed when erosion gullies exceed one foot in depth. • Mow to remove vegetation that obstructs flow and to maintain desirable vegetation. Dry retention basin — A shallow, dry basin with an outlet at the invert of the basin. Dry retention basins are constructed to attenuate peak discharges and temporarily detain runoff to promote sedimentation. Wet detention basin — A wet basin that maintains a permanent pool of water by using an elevated outlet control structure. Stormwater is treated through sedimentation and biological uptake of pollutants. Filtration basin — A shallow basin or sand filter with engineered or amended soil and an under -drain system. The basin detains stormwater and allows it to infiltrate through the soil, sand or engineered media. Treated stormwater is directed to the receiving water via the under -drain system. Infiltration basin — A shallow basin in permeable soils that detain and infiltrate stormwater. There is rarely an under -drain system unless needed to provide maintenance access. Infiltration basins use the natural filtering ability of the soil to remove pollutants from stormwater runoff. If problems are identified during inspections, a Work Order will be prepared in accordance with the following guidelines; • Replace surface soil or vegetation to maintain a layer of permeable soil or a dense cover of non - woody vegetation in the base of the infiltration area. • Correct any structural deficiencies that interfere with the function of the basin. • Remove undesirable vegetation, such as woody vegetation. 7