V4 12 Stormwater Maintenance Manual

• Cleaning and maintenance shall be scheduled during a relatively dry season. • Access and inspection to each subsurface detention basin is through the 4’X4’ Box Outlet structure associated with that basin, and the 36” access risers provided at each corner of the subsurface detention basins. Those structures as well as the 6” cleanout ports can be used for cleaning with a vacuum truck or a water-jetting device. • See HDPE Detention System Maintenance Technical Note (attached within this manual) for additional information. III. SURFACE DETENTION BASIN A. GENERAL MAINTENANCE • All detention basin components expected to receive and/or trap debris and sediment must be inspected for clogging and excessive debris and sediment accumulation at least four times annually as well as after every storm exceeding 1 inch of rainfall. These components shall include bottoms, riprap or gabion aprons and inflow points. • Sediment removal shall take place when the basin is thoroughly dry (See Appendix, Exhibit 1, for recommended hand tools). • Disposal of debris, trash, sediment, and other waste material must be done at suitable disposal/recycling sites and in compliance with all applicable local, state, and federal waste regulations. B. VEGETATED AREAS • Grass shall be mowed to a height of 2 to 3 inches at least once a month during the growing season. • Vegetated areas must be inspected at least annually for erosion and scour. • Vegetated areas shall also be inspected at least annually for unwanted growth, which shall be removed with minimum disruption to the bottom surface and remaining vegetation. • The structure must be inspected for unwanted tree growth at least once a year. 5