Storm water management assessment memorandum

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Page 19 of 20 Storm Water Management System Assessment Orono Truck Station Storm Water Pond Maintenance Schedule Maintenance Procedure Frequency Item Wetland Monitor wetland vegetation health and composition and replant lost vegetation. Spring and Fall,additionally as Vegetation Remove all wetland vegetation encroaching on inlet,outlet,and emergency needed to allow visual overflow structures. ins ection of the ond Non-native or The pond and pond surround should be inspected for the presence of non-native Spring and Fall,additionally as Invasive and invasive vegetation. Identified species should be removed—through mowing needed to allow visual Vegetation or other means recommended by the DNR.All vegetation on the berm which inspection of the pond im edes access to ond should be removed. Erosion Inspect pond and pond surround for bare or eroded soils,repair damaged areas. Spring and Fall,additionally as needed after large storm events or washouts occur Debris Inspect pond and pond surround for debris;dispose of all debris properly. Spring and Fall,additionally as debris build u is noticed Inlet and Outlet Inspect inlet and outlet structures(including all corresponding grates and orifices) Spring and Fall,additionally as Structures for clogging and damage.Remove sediment or debris from the structures. any problems with drainage are Replace damaged grates/valves. noted A report, including photos,should be made in conjunction with any cleanings or repairs to document the pond's condition.Frequent removal of sediment from outlets may be a sign of other unde�ying problems,such as erosion and loss of sediment stora e de th in the ond. Easily Inspect risers,barrels,embankments,and pipes for damage. Repair or replace Every one to three years, Accessible any damaged components. additionally as problems with Pond pond function arise Component A report,induding photos,should be made in conjunction with any repairs or re lacements to document the ond's condition. Hard to Reach Remotely inspect(i.e.televise)components that are not easily accessible,such as Every five to ten years, Pond under-drains,reverse slope pipes,or submerged/buried pipes.Repair or replace additionally as problems with Components damaged components. pond function arise A report,including photos,should be made in conjunction with any repairs or replacements to document the ond's condition. Sediment Visually monitor sediment depth during routine inspections.Complete survey of Monitor yearly, survey every 5 sediment depth and remove sediment when pond functionality is impaired. to 10 years,remove on a 5 to 10 or 15 year cycle based on rate of sediment accrual Normal The pond water elevation should be inspected to ensure that the normal water Annually,and more than 72 Water Level level is being maintained.Water levels below the outlet structure may signify a hours after large rainfall events For Retention leak in the outlet system.Water levels that remain above the outlet structure for Ponds lon er than 72 hours after a rainfall event ma si ni a clo in the s stem. Mosquitoes If problems with mosquitoes arise,possible solutions are participating in a As needed mosquito control program through the state or hiring a private contractor. Presence of mosquitoes may be a sign of another underlying problem,such as shallow onds in the pond embankment and sta nation.