12011 19TH AVE SE PARKING LOT 2021-12-23

No. 11 —Wetponds Maintenance Defect Condition When Maintenance Results Expected When Maintenance is Component is Needed Performed General Water level First cell is empty, doesn't hold Line the first cell to maintain at least 4 feet water. of water.Although the second cell may drain,the first cell must remain full to control turbulence of the incoming flow and reduce sediment resuspension. Trash and Accumulation that exceeds 1 Trash and debris removed from pond. Debris CF per 1000-SF of pond area. Inlet/Outlet Inlet/Outlet pipe clogged with No clogging or blockage in the inlet and Pipe sediment and/or debris material. outlet piping. Sediment Sediment accumulations in Sediment removed from pond bottom. Accumulation pond bottom that exceeds the in Pond depth of sediment zone plus 6- Bottom inches, usually in the first cell. Oil Sheen on Prevalent and visible oil sheen. Oil removed from water using oil- Water absorbent pads or vactor truck. Source of oil located and corrected. If chronic low levels of oil persist, plant wetland plants such as Juncus effusus(soft rush)which can uptake small concentrations of oil. Erosion Erosion of the pond's side Slopes stabilized using proper erosion slopes and/or scouring of the control measures and repair methods. pond bottom,that exceeds 6- inches,or where continued erosion is prevalent. Settlement of Any part of these components Dike/berm is repaired to specifications. Pond that has settled 4-inches or Dike/Berm lower than the design elevation, or inspector determines dike/berm is unsound. Internal Berm Berm dividing cells should be Berm surface is leveled so that water level. flows evenly over entire length of berm. Overflow Rock is missing and soil is Rocks replaced to specifications. Spillway exposed at top of spillway or outside slope. Volume V—Runoff Treatment BMPs—December 2014 4-44