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S C S E N G I N E E R S

Managing Leachate SeepsBelow Final Cover

Ali Khatami, Ph.D., P.E.SCS Engineers

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Leachate Seeps

• Many reasons for leachate seeps

• Operator manages leachate seeps while slope unclosed

• Various means and methods for management of leachate seeps

• Full closure and leachate seeps

• Partial closure and leachate seep

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Leachate Seeps Below Geomembrane

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Leachate Toe Drain System

(LTDS)

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Location of LTDS

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Leachate at Toe of Slope

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Leachate Pool at Perimeter Berm

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Removing Leachate by Vac Truck

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Vac Truck

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Exposing Anchor Trench

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Excavating Overfill

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Excavating Overfill

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Grading Slope

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Graded Slope

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Graded Slope

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Graded Slope

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LTDS Geocomposite Deployment

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LTDS Geocomposite

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LTDS Geocomposite

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Anchor Trench Excavation

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Anchor Trench for LTDS Geocomposite

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Bottom of LTDS Geocomposite

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Extension of LTDS Geocomposite

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Extended LTDS Geocomposite on Slope

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Anchor at High End of Seep

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Connection Points to Cleanouts

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Connection Point to Sump Riser

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Connection Point to Sump Riser

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Deployment of LTDS Geotextile

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LTDS Pipe Placement

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Vertical Pipe

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LTDS Pipe Placement

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Vertical Pipe

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LTDS Pipe Connection to Cleanout Pipe

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Connection of LTDS Pipe to Sump Riser

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Connection of LTDS Pipe to Sump Riser

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Connection of LTDS Pipe to Sump Riser

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LTDS Gravel Placement

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Forming Gravel around LTDS Pipe

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LTDS Gravel Placement

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LTDS Gravel Placement

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Gravel at End of LTDS Pipe

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Closing LTDS Burrito

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Placement of Soil Above LTDS Burrito

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Soil Above LTDS Burrito

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LTDS at Completion

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LTDS Pipe at Cell Construction Time

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LTDS Drain Pipes

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LTDS Drain Pipe into Leachate Sump

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LTDS Drain Pipe into Leachate Sump

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LTDS Drain Pipe into Leachate Sump

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Sump and LTDS Drain Pipe

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LTDS Drain Pipe at Leachate Sump

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LTDS Drain Pipe into Leachate Corridor

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Closed Burrito

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Cover Geomembrane Welded toBottom Geomembrane

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Cover Geomembrane Welded toBottom Geomembrane

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Granular Bentonite Over Extrusion Weld

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Granular Bentonite Over Extrusion Weld

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GCL Strip Over Granular Bentonite

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GCL Strip Over Granular Bentonite

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GCL Strip Over Granular Bentonite

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GCL Strip Over Granular Bentonite

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Cover Soil Placement

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Slope Final Condition

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Slope Final Condition

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Benefits of LTDS

• Collects and removes leachate below final cover geomembrane

• Eliminates ponding of leachate below final cover geomembrane at toe of slope

• Provides gas collection at toe of slope

• Connects to leachate collection sump, sump riser, or cleanouts

• Addresses aggressive leachate seeps on slope

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Construction Recommendations

• Construct LTDS and drain pipes at time of cell development

• Set LTDS pipe invert below top of berm

• Leave no sand between LTDS geocomposite and LTDS geotextile

• Construct vertical pipes for future connection to gas system

• Do not use sacrificial geomembrane over LTDS, use geotextile to allow infiltration