Loading...
HomeMy WebLinkAbout2016-96NMCWD/5-08 Declaration attachment C – Stormwater 1 ATTACHMENT C STORMWATER MANAGEMENT FACILITY MAINTENANCE SCHEDULE 1. All stormwater retention, detention and treatment basins must be inspected at least once a year to determine that basin retention and treatment characteristics are adequate. A storage treatment basin will be considered inadequate if sediment has decreased the wet storage volume by 50 percent or dry storage volume by 25 percent of its original design volume. Based on this inspection, if a stormwater basin requires sediment cleanout, the basin will be restored to its original design contours and vegetated state within one year of the inspection date. 2. All grit chambers, sump catch basins, sump manholes, outlet structures, culverts, outfall structures and other stormwater facilities for which maintenance requirements are not otherwise specified herein must be inspected in the spring, summer and fall of each year. Within 30 days of the inspection date, all accumulated sediment and debris must be removed such that each stormwater facility operates as designed and permitted. Contributing drainage areas must be kept clear of litter and vegetative debris, inflow pipes and overflow spillways kept clear, inlet areas kept clean, and undesirable vegetation removed. Erosion impairing the function or integrity of the facilities, if any, will be corrected, and any structural damage impairing or threatening to impair the function of the facilities must be repaired. 3. Volume control facilities and contributing drainage areas must be inspected every three months during the operational period (between spring snowmelt and first substantial snowfall) and monitored after rainfall events of 1 inch or more to ensure that the contributing drainage area is clear of litter and debris, inflow pipes and overflow spillways are clear, inlet areas are clean, undesirable vegetation is removed and there is no erosion impairing or threatening to impair the function of a facility. If sediment has accumulated in an infiltration feature, within 30 days of inspection deposited sediments must be removed, the infiltration capacity of the underlying soils must be restored, and any surface disturbance must be stabilized. Inspection must ensure that sediment traps and forebays are trapping sediment and that more than 50 NMCWD/5-08 Declaration attachment C – Stormwater 2 percent of the storage volume remains, the contributing drainage area is stable (i.e., no erosion is observed), and inlets and outlet/overflow spillways are in good conditions with no erosion. Maintenance techniques used must protect the infiltration capacity of the practice by limiting soil compaction to the greatest extent possible (e.g., by using low-impact earth-moving equipment). 4. Underground storage chambers must be inspected at least once a year to ensure that adequate storage capacity remains. Capacity will be considered inadequate if sediment has decreased the storage volume by 50 percent of its original design volume. Accumulated debris and sediment will be removed, and inlet and outlet structures will be cleared of any flow impediments. 5. The following guidelines shall be used to maintain the Stormwater Management areas (Underground Storage System) post construction. a) Establish a routine maintenance schedule. Maintenance shall occur in the spring (after snow melt) and fall (following leaf drop). The maintenance schedule can be adjusted based on actual observed site conditions. b) SPRING MAINTENANCE (following snow melt) • Sweep the parking lots tributary to the Underground Storage (UGS) system. This will minimize the amount of sediment, grits, trash, and debris that enters the UGS system. • Access the cleanout row through the upstream catch basin. Using a manufacturer recommended culvert cleaning nozzle, jet the cleaning row with the JetVac process. Vacuum accumulated sediments from the sump of MH 101. • Should direct access be required, follow local and OSHA rules for confined space entries. c) END OF SEASON MAINTENANCE (following leaf drop) • Collect leaves from lawn and parking lot areas. • Sweep the parking lots tributary to the Underground Storage (UGS) system. This will minimize the amount of sediment, grits, trash, leaf litter, lawn clippings, and debris that enters the UGS system. • Access the cleanout row through the upstream catch basin. Using a manufacturer recommended culvert cleaning nozzle, jet the NMCWD/5-08 Declaration attachment C – Stormwater 3 cleaning row with the JetVac process. Vacuum accumulated sediments from the sump of MH 101. • Should direct access be required, follow local and OSHA rules for confined space entries.