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TRANSCRIPT
Landfill LeachateCollection Pipe Design
Solid Waste Association of North AmericaNorth Carolina ChapterSpring ConferenceApril 25-28, 2016
Ali Khatami, Ph.D., P.E.SCS Engineers
Discussions
• Clogging at Leachate Collection Pipes• Traditional Design of Leachate Collection
Pipes• Innovative Design of Leachate Collection
Pipes• Construction Details
Clogging Issue
• Large quantities of leachate passing through a small area of geotextile potentially causes clogging
• Clogging reduces flow of leachate through geotextile
• Clogging of geotextile at leachate collection pipe potentially impedes free flow of leachate into the pipe
Rule of Transmissivities
Leachate must always flow from a transmissive medium into another medium with equal or greater transmissivity
Transmissivity Value Order
Waste < Sand < Geotextile < Geonet < Gravel < Pipe
Flow of water from left medium to right medium would be an ideal arrangement
Examples:Geotextile → Geotextile (√)Geotextile → Geonet (√)Geonet → Geotextile (X)Geotextile → Gravel (√)Geotextile → Sand (X)
Leachate Flow Path in Traditional Design
• from waste to sand layer (√)• from sand layer to upper geotextile of geocomposite (√)• from upper geotextile to geonet of geocomposite (√)• from geonet to upper geotextile of geocomposite (X)• from upper geotextile of geocomposite to geotextile
around gravel (√)• from geotextile to gravel (√)• from gravel to pipe (√)
Does Not Satisfy the “Rule of Transmissivities”
Leachate Flow Path in Innovative Design
• from waste to sand layer (√)• from sand layer to upper geotextile of
geocomposite (√)• from upper geotextile to geonet of
geocomposite (√)• from geonet to gravel (√)• from gravel to pipe (√)
Follows the “Rule of Transmissivities”