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Home My WebLink AboutSW5240302_O&M Agreement/Plan_20240419 (2) Wet Pond Maintenance Requirements Important operation and maintenance procedures: Immediately after the wet detention basin is established, the plants on the vegetated shelf and - perimeter of the basin should be watered twice weekly if needed, until the plants become established (commonly six weeks). No portion of the wet pond should be fertilized after the initial fertilization that is required to establish - the plants on the vegetated shelf. Stable groundcover will be maintained in the drainage area to reduce the sediment load to the wet - pond. If the pond must be drained for an emergency or to perform maintenance, the flushing of sediment - through the emergency drain will be minimized as much as possible. At least once annually, a dam safety expert will inspect the embankment. Any problems that are - found will be repaired immediately. The measuring device used to determine the sediment elevation shall be such that it will give an accurate depth reading and not readily penetrate into accumulated sediments. After the wet pond is established, it will be inspected quarterly and within 24 hours after every storm event greater than 1.0 inches (or 1.5 inches if in a Coastal County). Records of operation and maintenance shall be kept in a known set location and shall be available upon request. Inspection activities shall be performed as follows. Any problems that are found shall be repaired immediately. SCM element: Potential problem: How to remediate the problem: The entire wet pond Trash/debris is present. Remove the trash/debris. The perimeter of the wet Areas of bare soil and/or Regrade the soil if necessary to remove the gully, plant ground pond erosive gullies have cover and water until it is established. Provide lime and a one- formed. time fertilizer application. The inlet pipe is clogged (if Unclog the pipe. Dispose of the sediment off-site. applicable). The inlet pipe is cracked or otherwise damaged (if Repair or replace the pipe. The inlet device applicable). Erosion is occurring in the Regrade the swale if necessary and provide erosion control swale (if applicable). devices such as reinforced turf matting or riprap to avoid future problems with erosion. Sediment has accumulated to a depth Search for the source of the sediment and remedy the problem greater than the original if possible. Remove the sediment and dispose of it in a location design depth for sediment where it will not cause impacts to streams or the SCM. storage. The forebay Erosion has occurred. Provide additional erosion protection such as reinforced turf matting or riprap if needed to prevent future erosion problems. Weeds are present. Remove the weeds, preferably by hand. If pesticide is used, wipe it on the plants rather than spraying. Wet Pond Maintenance Requirements (Continued) SCM element: Potential problem: How to remediate the problem: Sediment has accumulated to a depth Search for the source of the sediment and remedy the problem greater than the original if possible. Remove the sediment and dispose of it in a location design sediment storage where it will not cause impacts to streams or the SCM. depth. The main treatment area Algal growth covers over 50% of the area. Consult a professional to remove and control the algal growth. • Cattails, phragmites or other invasive plants cover Remove the plants by wiping them with pesticide (do not spray). 50% of the basin surface. Best professional practices show that pruning is needed to Prune according to best professional practices. maintain optimal plant health. The vegetated shelf Determine the source of the problem: soils, hydrology, disease, Plants are dead, diseased etc. Remedy the problem and replace plants. Provide a one- or dying. time fertilizer application to establish the ground cover if a soil test indicates it is necessary. Weeds are present. Remove the weeds, preferably by hand. If pesticide is used, wipe it on the plants rather than spraying. Shrubs have started to Remove shrubs immediately. grow on the embankment. Evidence of muskrat or Consult a professional to remove muskrats or beavers and beaver activity is present. repair any holes or erosion. The embankment A tree has started to grow Consult a dam safety specialist to remove the tree. on the embankment. An annual inspection by an appropriate professional shows that Make all needed repairs immediately. the embankment needs repair. Clogging has occurred. Clean out the outlet device and dispose of any sediment in a gg g location where it will not cause impacts to streams or the SCM. The outlet device The outlet device is Repair or replace the outlet device. damaged. • Weeds or volunteer trees Remove the weeds or trees. are growing on the mat. Floating wetland island (if applicable) The anchor cable is damaged, disconnected or Restore the anchor cable to its design state. missing. Wet Pond Maintenance Requirements (Continued) SCM element: Potential problem: How to remediate the problem: Erosion or other signs of damage have occurred at Repair the damage and improve the flow dissipation structure. the outlet. The receiving water Discharges from the wet pond are causing erosion Contact the local NCDEQ Regional Office. or sedimentation in the receiving water. Wet Detention Pond Design Summary Wet Pond Diagram WET POND ID FOREBAY MAIN POND SMC1 Permanent Pool El. 634 Permanent Pool El. 634 Temporary Pool El: 635.85 Temporary Pool El: 635.85 Pretreatment other Clean Out Depth: 4 Clean Out Depth: 5 than forebay? No Sediment Removal El 630 Sediment Removal El 629 Has Veg. Filter? Yes Bottom Elevation: 629 Bottom Elevation: 628 WET POND ID FOREBAY MAIN POND SCM2 Permanent Pool El. 643.5 Permanent Pool El. 643.5 Temporary Pool El: 644.55 Temporary Pool El: 644.5 Pretreatment other Clean Out Depth: 3.5 Clean Out Depth: 4.5 than forebay? No Sediment Removal El 640 Sediment Removal El 639 Has Veg. Filter? Yes Bottom Elevation: 639 Bottom Elevation: 638 WET POND ID FOREBAY MAIN POND SCM3 Permanent Pool El. 636 Permanent Pool El. 636 Temporary Pool El: 637.5 Temporary Pool El: 637.5 Pretreatment other Clean Out Depth: 5 Clean Out Depth: 6 than forebay? No Sediment Removal El 631 Sediment Removal El 630 Has Veg. Filter? Yes Bottom Elevation: 630 Bottom Elevation: 629 ATTACH ADDITIONAL SHEETS IF NECESSARY Low Density Maintenance Requirements Important maintenance procedures: The drainage area to the vegetated conveyance or vegetated receiving area will be carefully managed to reduce the sediment load to the vegetated conveyance or vegetated receiving area. After the initial fertilization to establish the grass in the vegetated conveyance or the vegetated receiving area, fertilizer will not be applied to the vegetated receiving areas. The vegetated conveyance or vegetated receiving area will be inspected quarterly. Records of operation and maintenance will be kept in a known set location and will be available upon request. Inspection activities shall be performed as follows. Any problems that are found shall be repaired immediately. SCM element: Potential problem: How to remediate the problem: Vegetation is too short or Maintain grassed vegetation such that the swale or vegetated Vegetation too long. area does not erode during the peak flow from the 10-year storm Trash/debris is present. Remove the trash/debris. Vegetated receiving Areas of bare soil and/or Regrade the soil if necessary to remove the gully, and then re- areas erosive gullies have sod (or plant with other appropriate species) and water until formed. established. Provide lime and a one-time fertilizer application. Clogging has occurred. Clean out the outlet device. Dispose of the sediment off-site. The outlet device (if applicable) The outlet device is Repair or replace the outlet device. damaged Erosion or other signs of damage have occurred at Repair the damage and improve the flow dissipation structure. the outlet. The receiving water Discharges from the site are causing erosion or Contact the local NCDEQ Regional Office. sedimentation in the receiving water.