All landfills need impermeable cover materials eventually when they shut down. Without this layer as part of the cap and cover, water will continually seep through the trash and increase the leachate flooding out of the bottom. However, a cover is not enough to complete a landfill containment system. It’s only one part of a larger design that begins with the liner at the bottom. While they are rarely joined together due to the layers of trash between them, these two layers nonetheless work together to contain leachate and direct it to a safe holding pond or pumping point. Without a liner, a rain cover is only half of the system.
Seepage Control
Covers can stop water from entering the cell, but they can’t stop seepage from occurring under the surface. Since nearly all waste products generate at least a little water as they break down and decompose, it’s inevitable that water will begin to seep out from the bottom of a landfill cell. Lining the cell is the only way to control that process and stop seepage. Seepage is the slow, gravity-driven cycle in which water creeps through any porous surface. Even solid rock under the ground can’t stop seepage due to tiny openings in the rock. Only a material built for impermeability, such as a geomembrane made from RPE, can actually stop seepage from spreading leachate to the surrounding environment. Since the cover is installed or used above the layers where leachate develops, they must be used together with liners.
Permeable Materials
Many landfill cells are reinforced in some way with a material that may seem like a liner but is actually too permeable to use on its own. Clay is a great example because it was once used as a liner material on its own. Unfortunately, even adding polymer liquids and compacting the soil won’t create a truly seepage-proof surface. Concrete and asphalt also slowly lose liquid over time, just like rock does, due to the presence of tiny openings. Even if a design calls for using any of these materials to smooth and support the sides of the landfill cell, make sure they’re not considered the only liner material.
Don’t confuse the use of temporary landfill rain covers as eliminating the need for liners. Both must be used on the same cell to truly keep leachate levels under control. Thankfully, they’re also both available from the same source here at BTL Liners.
Conclusions
What seems like just a little rainstorm to a resident near a landfill may be a big event to the staff managing it. Without reliable rain covers, it’s all too easy for a storm to cause a leachate management system to overflow. Today’s automatic cover systems make it easier than ever to use alternatives to soil, but they must be fitted with durable materials to work properly. We have everything you need for permanent and temporary rain covers here at BTL Liners.
