Leachate Seep Collection and Management System below Landfill

Leachate Seep Collection and Management System below Landfill Final Covers Solid Waste Association of North America North Carolina Chapter Spring Conference April 4 -6, 2017 Ali Khatami, Ph. D. , P. E. SCS Engineers

Leachate Seeps 1. Many reasons for leachate seeps 2. Operator manages leachate seeps while slope unclosed 3. Various means and methods for management of leachate seeps

Leachate Seep after Closure Leachate seeps may continue after a partial closure if source of water is outside the closed area or leachate mounds leading to the closed area exist 3

Leachate Seep Dilemma 1. No means to control leachate seeps below cover geomembrane 2. Leachate ponding at toe of slope 3. Forming of soft cushioning areas at toe 4. Increasing in size by time 5. Opening geomembrane, pumping, and reclosing 6. Reappearing of soft areas after some time 4

Leachate Seeps Below Geomembrane

Location of LTDS

Construction of LTDS • During closing of slope • During cell construction

LTDS Construction during Closing of Slope

Exposing Anchor Trench

Leachate at Toe of Slope

Excavating Overfill

Grading Slope

Graded Slope

LTDS Geocomposite Deployment

LTDS Geocomposite

Anchor Trench Excavation

Anchor Trench for LTDS Geocomposite

Extended LTDS Geocomposite on Slope

Anchor at High End of Seep

Bottom of LTDS Geocomposite

Deployment of LTDS Geotextile

LTDS Pipe Placement

Connection Points to Cleanouts

LTDS Pipe Connection to Cleanout pipe

Connection Point to Sump Riser

Connection of LTDS Pipe to Sump Riser

Connection of LTDS Pipe to Sump Riser

Vertical Pipe

Forming Gravel around LTDS Pipe

Vertical Pipe

Closing LTDS Burrito

Placement of Soil Above LTDS Burrito

Soil Above LTDS Burrito

Cover Geomembrane Welded to Bottom Geomembrane

LTDS Construction during Cell Development

LTDS Pipe at Cell Construction Time

LTDS Drain Pipe into Leachate Sump

LTDS Drain Pipe at Leachate Sump

LTDS Gravel Placement

Closed Burrito

Benefits of LTDS 1. Collects and removes leachate below final cover geomembrane 2. Eliminates ponding of leachate below final cover geomembrane at toe of slope 3. Provides gas collection at toe of slope 4. Connects to leachate collection sump, sump riser, or cleanouts 5. Addresses aggressive leachate seeps on slope

Construction Recommendations 1. Construct LTDS and drain pipes at time of cell development 2. Set LTDS pipe invert below top of berm 3. Leave no sand between LTDS geocomposite and LTDS geotextile 4. Construct vertical pipes for future connection to gas system 5. Do not use sacrificial geomembrane over LTDS, use geotextile to allow infiltration

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