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e remove sediment (i.e., after reaching a specified depth, sediment should be removed y <br /> from BMP facilities, as well as from any pretreatment devices, such as forebays or <br /> sedimentation catchbasins) <br /> • regrade (i.e., swales and ponds will need to be regraded and vegetated after — <br /> sediment removal is completed) <br /> • inspect(i.e., inspect inlet/outlet, vegetation, sediment loading, and slopes) <br /> • clean inlet/outlet(i.e., clean obstructed or blocked orifices) <br /> • rototill/disk/aerate (i.e., following sediment removal of an infiltration facility, the <br /> bottom of the vegetated area should be rototilled, disked or aerated) <br /> The frequencies of maintenance activities in Table 2 were obtained from literature <br /> including the Unified Sewerage Agency's Conveyance System Management Study(USA, <br /> 1998), and the Watershed Management Institute's Operation, Maintenance, & <br />' Management of Stormwater Management (WMI, 1997), and from personal <br /> communications with other regional jurisdictions. <br /> Table 2 <br /> Maintenance Requirements for BMP Facilities <br /> Maintenance Activity and Average Frequency/Year <br /> 1 \ <br /> x <br /> b <br /> 03 ,t3 >C > 4) -= <br /> 0 oca <br /> BMP > c) 61 P: to n: U .. . P4 % <br /> K "egetra' e ..._ <br /> Swales 4 4 .5 .2 1 1 <br /> Filter Strips 4 4 .5 .2 1 <br /> _ o X11 , irkil'ondW <br /> Wet Ponds 1 4 .2 2 4 4 <br /> Dry ED Ponds 4 4 .2 .2 4 4 <br /> Wet ED Ponds 1 4 .2 2 4 4 <br /> Stormwater Marsh/Wetland 1 4 <br /> .2 _ 4 4 <br /> cih �. 5 <br /> Dry Wells/Infiltration Vaults -`" <br /> — — <br /> Infiltration Trench 4 .5 4 1 <br /> Infltration/Retention <br /> Basin 4 4 .2 .2 4 4 1 <br /> Sidi .�.tructu a Sid.i7 - _ <br /> a... .�. ...� n lira' ' .. •HX4*,.wK A,.i F.ti tiy.11,. <br /> Structural Storm Sewer <br /> Devices 1 1 1 <br /> Note: <br /> A frequency of 0.2 indicates that the activity is only necessary once every five years.A frequency of <br /> 0.5 indicates that the activity is only necessary once every 2 years. Infiltration facilities may require <br /> replacement,however activities associated with replacement of infiltration facilities are not included in the <br /> table. <br /> Table 3 provides a summary of the equipment and staff needed to perform the required <br /> maintenance activities, and the estimated cost to complete the annual maintenance for <br /> each BMP. The costs are representative of average facilities maintained under typical <br /> I:\945042ne\task0400\memo8\Stormwater Policy Team Meeting.doc 4 <br />