Shredders

Machinery that chops and cuts herbaceous and woody plant materials and organic sediments and allows them to sink to the bottom, or facilitates the harvest of floating debris.

Considerations:

(Refer to floating island and tussocks to understand origin and impacts.)

Water uses and functions

  • Applied when other control methods are not feasible or when expedited control is required
  • Flood control
    • Shred jams in flood control structures
    • Unplug jams in outfall canals, streams, rivers, or other conveyances
  • Transportation / navigation
    • Shred plant masses or organic material jammed against bridges
    • Shred plant masses or organic material blocking established navigation channels
  • Control drifting floating islands or tussocks in urgent or preemptive situations
    • Prevent potential damage to public and private property i.e. docks, bridges, etc.
    • Recreation and safety - prevent blockages to trails and public boat ramps

Fish and wildlife

  • Avoid shredding during wildlife nesting or fish bedding periods if possible
  • Prevent plant masses from covering valuable fish and wildlife habitat
  • Non-selective - controls plants and animals that cannot escape its path

Control feasibility

  • Shredding generally proceeds faster and is less expensive that harvesting
  • Expenses are generally high
    • Acquisition cost of machinery
    • High maintenance
    • Operating costs - depends on plant type and suspended organic composition
      • herbaceous vs. woody plants vs. trees up to 10 inches in diameter
      • no suspended organic material to peat up to four feet thick
  • Minimize adverse impacts to extent possible when shredding floating islands or tussocks
    • More difficult in emergency than urgent or preventive situations
    • Turbidity
      • Shred from interior of floating island or tussock toward outside
      • Leave edge for containment barrier
      • Allow as much shredded material to sink or decompose prior to harvesting barrier
    • Sediment accumulation
      • Shred floating islands where they arise - return organic material to point of origin
      • Shred as finely as possible to enhance decomposition
    • Try to avoid:
      • repeated shredding in same area
      • shredding on residential shoreline or public beaches
      • in canals or established navigation channels
    • Harvest floating shredded material where feasible - refer to harvesting considerations
      • Most material sinks to bottom while some remains at surface
      • Gasses build up during decomposition and may resurface organic material
      • Allowing shredded material to remain at surface as long as possible
      • Exposure to air enhances decomposition and compacts organics
      • Reshred material or harvest when vegetation grows over exposed organics
    • Push or guide floating islands to lower use or value area if possible prior to shredding

Other considerations

  • Avoid shredding notches or irregular areas in fixed-in-place tussocks or floating islands
  • Wind or water currents will catch edge breaking new material loose

Examples of Feasible Control:

  • Emergency shredding of floating islands blocking structures or outfalls alleviated flooding in Marion Creek, and Lakes Hancock, Miccosukee, Apopka and Runnymeade
  • Emergency shredding of floating tussocks prevented damage to bridges over the Withlacoochee and St Johns Rivers
  • Shredding drifting islands in Orange Lake and Tsala Apopka prevented boaters from being stranded and prevented from returning to public boat ramps
  • Shredding and harvesting drifting floating islands in Lakes Pierce and Apopka prevented further damage to boat docks and boat ramps
  • Shredding reopened navigation channels overgrown by floating tussocks in tributary creeks of the St Johns River and Lake Lafayette
  • Shredders chopped up about 1,000 acres of floating islands and tussocks to facilitate dredging operations on Lake Panasoffkee
     

Last updated: 27 June 2011