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OPERATION & MAINTENANCE MANUAL <br /> BIOFILTRATION AREA <br /> Maintenance Defect Conditions When Maintenance is Desired Conditions <br /> Component Needed <br /> Biofiltration area Sediment Accumulation Sediment depth exceeds 2". No sediment deposits on grass <br /> on Grass Layer layer of the biofiltration swale, <br /> which would impede filtration of <br /> runoff <br /> Vegetation When the grass becomes excessively tall Vegetation is mowed or <br /> (greater than 10");when nuisances,weeds, nuisance vegetation is <br /> and other vegetation start to take over eradicated,such that flow is not <br /> impeded. Grass should be <br /> mowed to a height between 4& <br /> 9 inches. Grass should be not <br /> be mowed below design flow <br /> level. <br /> Inlet/Outlet Pipe Inlet/outlet pipe clogged with No clogging or blockage in the <br /> sediment/debris. inlet or outlet piping. <br /> Trash&Debris Trash and debris accumulated in the Trash and debris removed from <br /> Accumulation biofiltration swale. biofiltration swale. <br /> Erosion/Scouring Where the biofiltration swale has eroded or Biofiltration swales should be <br /> scoured the bottom due to flow channelization re-graded and re-seeded to <br /> or higher flows. specification,to eliminate <br /> channeled flow. Overseeded <br /> when bare spots are evident. <br /> Heavy metal deposition When significant heavy metal deposition is Mulch is replaced annually. <br /> suspected(swales downstream of roads and Maintain 2 to 3 inch mulch <br /> parking) depth. <br /> Watering While plants are being established(2 to 3 Plants have been established and <br /> years) no longer need to be watered. <br /> ENERGY DISSIPATERS <br /> 5 <br />