Method of draining leachate from an existing landfill

A method of draining leachate from an existing landfill cell by retrofitting the landfill cell with a lateral drainage pipe, wherein the landfill cell includes a base, solid waste disposed above the base, and a cap overlying the solid waste, the base including a liner, the cap including a top surface having portions thereof situated at different respective elevations, wherein leachate from the solid waste tends to accumulate above the base, the method comprising the steps of:

• A. installing an entry tube through the top surface of the cap, and sealing the entry tube with respect to surrounding material of the cap;
• then
• B. introducing a drill string through the entry tube and causing a drill bit to drill a hole through the solid waste along a path situated above the base in an upwardly inclined direction from the entry opening, the hole passing completely through the waste material to define an exit opening at an elevation higher than the entry tube;
• C. replacing the drill bit with a reamer at the exit opening and back-reaming through the hole to enlarge the diameter of the hole;
• D. allowing leachate and drilling fluid from the drill bit to gravitate outwardly through the entry tube during step C;
• E. installing an exit tube in the exit opening;
• then
• F. installing a perforated drain pipe in the hole;
• then
• G. passing a nozzle through the drain pipe for emitting a high-pressure liquid jet generally radially outwardly through the drain pipe and into the surrounding solid waste to form a drainage layer of waste material around the drain pipe;
• and
• H. forming seals in the spaces formed by the drain pipe with the entry and exit tubes, respectively, subsequent to step F;
• and
• I. allowing leachate to enter the perforated drain pipe and drain from the landfill cell by gravity.

In a method of installing a lateral drain pipe in an existing landfill cell for draining leachate therefrom, the landfill including a base, solid waste disposed above the base, and a cap overlying the solid waste, wherein the drain pipe is installed in a lateral hole drilled through the waste material, the method comprising the steps of:

• A. installing an entry tube through the cap, and
• B. forming a gas/liquid seal around the entry tube where the entry tube intersects the cap by:
• 1. embedding the entry tube in a layer of clay-like material, and
• 2. surrounding the entry tube with a piece of plastic material.