The Hydrology of Wetlands and Clay Settling Ponds

1
The Hydrology of WetlandsandClay Settling Ponds

• Patrick Tara P.E.
• Ken Trout
• Center for Modeling Hydrologic
• and Aquatic Systems
• University of South Florida

2
Wetland Functions

• Biological Productivity
• Flora (Dense/Diverse)
• Fauna
• Filtration/Treatment
• Filter Sediments
• Treat Nutrients
• Water Storage
• Reduces Flooding
• Increases Dry Flows
• Interacts with Aquifer

3
Hydrologic Cycle
Hydrologic Cycle
Interception
Precipitation
Transpiration
Interflow
Infiltration
Impervious Lens
Evaporation
Evaporation
Percolation
Runoff
Wetlands/Streams
Groundwater Flow
Baseflow
Water Table
Leakage
Unconfined Aquifer
Aquitard (Confining Unit)
Confined or Artesian Aquifer
4
Hydrology of Wetlands
Storage
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Storage Attenuation
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Natural Wetlands inSouthwest Florida

• Wetlands Cover 25-30 of the Landscape
• Need the storage
• Shallow slopes dictate large area
• Wetlands Can be Connected or Disconnected
• Some wetlands never discharge
• Some discharge only during extreme conditions
• Wetlands Recharge/Discharge Aquifer
• Best analyzed with technology that integrates
  both surface water and groundwater

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Consolidation of Waste Clay

• Waste Clays Consolidate as Water is Removed
• Drainage
• Evaporation
• Ultimate Thickness Approximately ½ Initial
  Thickness
• Initial thickness varies in CSA

Source BCI FIPR 94-03-1095
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Ultimate Consolidation

• Clay Pond Continuously Consolidating
• Storage Changing

Source BCI FIPR 94-03-1095
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Simulated Ultimate Consolidation
Reclaimed Elevation
Elevation After 15 Years
Elevation After 30 Years
Consolidation Occurs Many Years After Reclamation
Source BCI FIPR 94-03-1095
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The Effects of Consolidation

• Increased Storage Will Attenuate Storm Response
• As Clay Consolidates Littoral Shelf Depth
  Increases

Source BCI FIPR 94-03-1095
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Differential Settling
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Clay Permeability

• Permeability of Waste Clays Function of Void
  Ratio
• As Waste Clays Consolidate the Permeability
  Decreases Preventing Percolation

Source BCI FIPR 94-03-1095
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Hydrology of Clay Settling Ponds
Storage???
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Wetland Functions on CSAs

• Biological Productivity
• Flora (Dense/Diverse)
• Fauna
• Filtration/Treatment
• Filter Sediments
• Treat Nutrients
• Water Storage
• Reduces Flooding
• Increases Dry Flows
• Interacts with Aquifer

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Summary

• Wetlands can be constructed on CSAs although
  some functionality wont be available
• Inflow/outflow may be restored through design
• Structure/wetland maintenance may be required to
  accommodate changing topography in CSAs
• More study is needed