The various levels and layers of a sanitary landfill require different forms of liners and sealant. The end goal for a modern sanitary landfill is to create a sealed container around the entire landfill to protect the outside environment as the waste degrades. The materials used must be watertight, durable, and resistant to chemicals, as leaks can be costly and difficult to fix. Leachate and methane are also contained in order to be collected and removed.
BTL’s ArmorPro series includes strong, flexible, and chemically resistant liners built on XR technology. These liners are designed to outlast HDPE and other popular liner materials in even the most extreme conditions and against the toughest contaminants. The XR-3 geomembrane is an affordable, durable option for landfill liners. It’s constructed with a nylon woven reinforcement layer sandwiched between EIA coatings that are extremely stable even within an adverse environment. XR liners offer maximum containment and protection for even highly challenging substances. Whenever it’s necessary to minimize or prevent toxic leachate from moving into nearby rivers, underlying aquifers or surrounding soil, the ArmorPro series of XR liners from BTL Liners are an outstanding choice.
Clay Liners
Clay liners, most often made of bentonite clay, are convenient for their relatively small environmental impact and low initial cost. However, puddled clay is easily spread too thin during the application, resulting in a less than watertight seal. The sensitivity of this step makes clay liners practically as tricky to install as their geomembrane alternatives. Clay also allows the permeation of chemicals and nutrients between water and the underlying soil. A soft clay liner is also easily disturbed by wildlife or erosion. Damage is tough to identify and locate, and frequently complete reinstallation of another lining solution is necessary.
Concrete Liners
Frequently, waste ponds are built using precast or poured concrete. Concrete is porous, and capillary action will quickly pull water through the material towards the earth below. Sealants will protect the concrete from permeation for some time but aren't permanent. A geomembrane liner serving as an underlayment between the concrete and the soil will be a waterproof layer. This will keep any water from soaking into the ground when it makes its way through cracks or pores. Additionally, this will protect the concrete from underground movement (like traffic or minor tremors).
Geomembranes
These include high density polyethylene (HDPL), polypropylene (PPL), and polyvinyl chloride (PVC). Different liner products and configurations are typically evaluated based on price, performance and availability, as well as their reputation for reliability over time. Since geomembranes can be custom fabricated and shipped directly to the site for quick installation, the savings can be substantial when compared to other liner options that must be constructed on-site, like in the case of concrete or clay.
Durability
Waste materials found within waste lagoons can be heavy and corrosive, tending to distort non-reinforced liner products, stretching them like a balloon. This increases wear and risk of tears or impacting the ability of liquids to flow within a collection layer. Reinforced polyethylene (RPE) is designed to resist this type of expansion under heavy loads. One excellent example is BTL’s innovative AquaArmor, which combines layers of woven HDPE or other reinforcing layers to limit stretching and bulging while sandwiched between engineered coatings to provide exceptional toughness.
Chemical and temperature effects on geomembranes can also alter their performance, and selection of liners that are inert to possible chemicals and chemical processes in a storage facility is critical. Consideration of possible (not simply typical) temperature extremes should also be considered. As the effects of changing weather patterns become evident, it has become clear that planning and designing for a range of only 100 year temperature or rainfall extremes is insufficient.
Punctures and increased wear from waste materials such as crushed rock or broken plastics can impact the integrity and longevity of a liner. This can be mitigated by the addition of a small layer of sand between the rock and liner or the use of a thin cushioning underlayment, but the use of a reinforced liner specifically engineered to withstand abrasion and wear, such as BTL’s AquaArmor, is advised.
Installation
Geomembrane liners are fabricated and shipped to a site in large rolls. They can be customized to fit the specific topography of a site, permitting rapid installation. Liners of this type are relatively thin, however, and care must be taken to avoid damage before, during and after installation. In fact, most leaks involving geosynthetics arise from defects in installation - usually at joints and seams. Rigorous quality control and assurance programs exercised during construction and installation should eliminate these issues, resulting in a well-engineered system which virtually eliminates the risk of environmental contamination through seepage or leaks.
PVC Liners (Polyvinyl Chloride)
These are very common in small backyard pond projects due to their affordability and ease to purchase and set up. Conventional PVC isn't as durable as other liners and usually has a lifespan of only ten years. PVC also lacks the U.V. protection found in newer liner technology, meaning they need to be buried to avoid brittleness and damage from sun and movement. Tears are common throughout installation and use, and frequent disturbance for maintenance only contributes to the problem.
EPDM Liners (Ethylene Propylene Diene Monomer)
This is a popular kind of synthetic rubber liner. This is more durable than PVC and is accordingly thicker and heavier. This more robust liner is still somewhat flexible, but its weight and general unwieldiness complicate shipping and installation. EPDM liners are sealed using adhesive tape, and any mistakes during installation will significantly impact the liner's permeability. EPDM is less sensitive to U.V. damage than PVC but still needs protection from long-term sunlight and decay. Leaks are easier to locate and repair in EPDM liners than the above. However, the rubber is susceptible to punctures from wildlife or damage during installation.
HDPE Liners (High-Density Polyethylene)
These geomembranes are increasingly popular options as they become cheaper and more available. These are thick and stiffer than PVC or EPDM liners and are incredibly resistant to U.V. degradation and tearing. Despite their durability, HDPE liners are lighter than their EPDM cousins. However, the material's stiffness means that any folds or creases are permanent -- these liners would require professional installation. Their seams are heat-welded, leaving their watertight seal virtually permanent. Holes and damage are patchable, saving you the cost and trouble of choosing and installing an entirely new solution. HDPE liners are also chemical-resistant, protecting the surrounding soil and local watershed. (In situations where RPE liners involve unavailable expense, HDPE is a worthy alternative).
RPE Liners (reinforced polyethylene)
RPE liners are on the frontlines of geotextile technology today. These are lightweight, durable, and UV-resistant. RPE liners are welded using the same heat technology as HDPE liners, reducing the frequency and severity of damage from installation or wear-and-tear. They are also built to be chemical-resistant, preventing seepage from chemical-rich irrigation water into groundwater aquifers beneath the soil. RPE is also built to avoid the leaching of internal chemicals, essential for water used on crops. BTL has manufactured RPE liner panels in immense sizes beyond 150,000 sq ft. The lightweight flexibility of RPE liners means that even the largest panels can be factory-welded to combine and deliver installation-ready. RPE is also simpler to install, meaning that in all but the largest projects, manual installation is possible. BTL and our team of experts installed an RPE liner in a 40-acre irrigation reservoir manually in only four days.
