Almost all new landfills designed for solid waste in the U.S. follow the cell design. This allows for a segmented approach to large and small properties alike, creating more opportunities for control to prevent collapses and leachate losses. A landfill cell may seem like a simple, basin-type structure, but it’s actually quite complicated since it must contain both solid and liquid waste products for long periods of time. Everything from the projected amount of settling to the annual rainfall on the site affects the final design and how well it performs. By taking care with every step of landfill cell design, it’s possible to create cells that are easy to securely cap and require less maintenance over the years.
What is a Cell?
A landfill cell is a single, waste-holding unit within the larger landfill property. These cells are generally shaped as basins during excavation, with berms running along the sides to contain leachate and other liquids. Of course, these berms only offer containment and control when they’re lined with an impermeable barrier. Landfills will contain multiple distinct cells in order to rotate the filling of each of them. In most high-volume facilities, cells are rotated daily and covered with a layer of soil to control odor and trash movement due to wind. Less commonly used landfills, for commercial or construction waste, may only receive weekly or monthly covering and rotation between cells. No matter the pattern of use, separating the facility into distinct storage areas offers multiple benefits over old-fashioned open designs.
Basic Features
Each landfill needs a unique cell design for the site’s conditions, but most of them share many common features. Some of the basic features for almost all landfill cells include:
- A compacted base of either natural soil or imported clay to create a smooth and puncture-free surface for supporting the liner
- Drains and spill detection systems under or integrated into the liner to manage any leachate that reaches the bottom of the cell
- Berms to complement the excavation into the ground, which creates extra holding space and assists in the capping process at the end
- Impermeable liners at the bottom of the trash layers that is further topped by a semi-permeable leachate collection system
- Methane capture systems that either accumulate the gas for further use or disperse it safely to the atmosphere.
Benefits Over Open Designs
Open dumps are as loosely organized as the name suggests. The first attempts at organizing modern solid waste that is slow to decompose, including plastics and scrap metal, were large mounds simply piled out on open ground. There were little to no liner materials used for these designs, allowing water to trickle down through the mounded trash and flush large amounts of chemicals and contaminants into the soil and ground water. In contrast, modern landfill cells are carefully designed with long-term, safe storage in mind. Liners and caps combine to keep water out, minimizing the amount of water that must be pumped out of the collection layer. It’s essential that the last layer under the trash, or the first layer installed during construction, is an impermeable geomembrane. This material must control water seepage as much as possible to prevent these contamination issues.
Challenges of Long-Term Landfill Use
The longer a landfill stays open, the more of a chance it has to accumulate rainwater. Cell patterns help address these issues by minimizing exposure on a daily or weekly basis. Leaving liner and capping materials exposed during daily use of the landfill cells can also result in weakened materials that can’t last for years. Careful design is the best way to prevent all of these challenges and more. UV-resistant materials, from a reliable manufacturer like BTL Liners, allow you to leave liners and capping covers exposed as necessary without damage.
Who Regulates Landfill Cell Design?
Like with most forms of potentially hazardous waste, the Environmental Protection Agency (EPA) has the highest level of federal control over new landfill cell design. The Resource Conservation and Recovery Act (RCRA) in particular gave the EPA control over landfill design and permitting, including how leachate and solid waste alike are handled. Unlike other EPA regulations, the RCRA allows the agency to exert control over non-hazardous solid waste as well. This is why landfills that will only hold municipal waste, like diapers and food scraps, still must comply with federal, state, and local regulations on so many different levels.
Potential for Land Reuse
By managing leachate development and controlling settling to prevent unexpected sinkhole development, it’s possible to reuse former landfill space. Many successful housing developments, parks, golf courses, and even schools have been built over former landfills. These projects are much easier to accomplish, not to mention less expensive, when the facility is divided from the start into multiple cells. Cells are much more stable and easier to cap than open landfill spaces, making the space faster and more affordable to reclaim.
Landfill cells represent some of today’s best technology for waste management all combined into a single integrated design. Yet, they can still only perform as desired when built correctly from the start. Impermeable liners, made from durable materials like RPE, are the only option for completely sealing off the bottom of a new landfill cell system. The same materials also work well for controlling both gas and liquid infiltration when each cell is permanently capped. Choose BTL Liners as your supplier for both liner and capping materials for landfill cells of all sizes and types.
