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No.2—Infiltration Facilities <br /> Maintenance Defect Conditions When Maintenance Is Needed Results Expected When <br /> Component Maintenance Is <br /> Performed <br /> General Trash&Debris Function of facility is impaired by or likely to Trash and debris is <br /> be impaired by trash and debris. removed. <br /> Vegetation Function of facility is impaired by vegetation. Vegetation is removed or <br /> managed to restore proper <br /> function of facility. <br /> Use of herbicides shall be in <br /> accordance with applicable <br /> regulations. <br /> Contaminants and Any evidence of oil,gasoline,contaminants or Contaminants or pollutants <br /> Pollution other pollutants are removed <br /> Note:Coordinate removal/cleanup with local <br /> and/or state water quality response agency. <br /> Erosion Eroded damage over 2 inches deep where cause Slopes are stabilized using <br /> of damage is still present or where there is appropriate erosion control <br /> potential for continued erosion. measure(s);e.g.,rock <br /> reinforcement,planting of <br /> grass,compaction. <br /> Storage Area Sediment Water ponding in infiltration pond after rainfall Sediment is removed and/or <br /> ceases and appropriate time allowed for facility is cleaned so that <br /> infiltration. infiltration system works <br /> (A percolation test pit or test of facility according to design. <br /> indicates facility is only working at 90%of its <br /> designed capabilities. If two inches or more <br /> sediment is present,remove). <br /> Filter Bags(if Sediment and Debris Sediment and debris fill bag more than 1/2 full. Filter bag is replaced or <br /> applicable) system is redesigned. <br /> Rock Filters Sediment and Debris By visual inspection,little or no water flows Gravel in rock filter is <br /> through filter during heavy rain storms. replaced. <br /> Side Slopes of Pond Erosion See"Detention Ponds"(No.1). See"Detention Ponds"(No. <br /> 1). <br /> Berms Settling Any part of a berm which has settled at least 4 Berm is repaired and <br /> inches lower than the design elevation. restored to the design <br /> If settlement is apparent,measure berm to elevation. <br /> determine amount of settlement. <br /> Settling can be an indication of more severe <br /> problems with the berm or outlet works. Note: <br /> A licensed civil engineer may be needed to <br /> determine the cause of the settlement. <br /> Erosion Any erosion observed on a compacted structural Slopes should be stabilized <br /> berm embankment, using appropriate erosion <br /> Note: A licensed civil engineer may be needed control measure(s);e.g., <br /> to inspect,evaluate and recommend a repair rock reinforcement,planting <br /> plan of grass,compaction. <br /> January 2016 Snohomish County Drainage Manual Volume V-Runoff Treatment BMPs 26 <br />