Lake Pocotopaug Lake and Watershed Restoration Evaluation ...

TABLE 21 continued. MANAGEMENT OPTIONS FOR CONTROL OF ALGAEOPTION MODE OF ACTION ADVANTAGES DISADVANTAGESPhysical Controls5.a) “Dry” excavation ♦ Lake drained or lowered tomaximum extent practical♦ Target material dried tomaximum extent possible♦ Conventional excavationequipment used to removesediments5.b) “Wet” excavation ♦ Lake level may be lowered,but sediments notsubstantially exposed♦ Draglines, bucket dredges, orlong-reach backhoes used toremove sediment5.c) Hydraulic removal ♦ Lake level not reduced♦ Suction or cutterheaddredges create slurry which ishydraulically pumped tocontainment area♦ Slurry is dewatered; sedimentretained, water discharged♦♦♦♦♦♦♦♦♦Tends to facilitate a verythorough effortMay allow drying of sedimentsprior to removalAllows use of less specializedequipmentRequires least preparationtime or effort, tends to be leastcost dredging approachMay allow use of easilyacquired equipmentMay preserve aquatic biotaCreates minimal turbidity andimpact on biotaCan allow some lake usesduring dredgingAllows removal with limitedaccess or shorelinedisturbance♦♦♦♦♦♦♦♦♦♦♦Eliminates most aquatic biotaunless a portion left undrainedEliminates lake use duringdredgingUsually creates extreme turbidityTends to result in sedimentdeposition in surrounding areaNormally requires intermediatecontainment area to drysediments prior to haulingMay cause severe disruption ofecological functionUsually eliminates most lakeuses during dredgingOften leaves some sedimentbehindCannot handle coarse or debrisladenmaterialsRequires sophisticated and moreexpensive containment areaRequires overflow dischargefrom containment areaLake Pocotopaug Restoration Evaluation 112May 2002