What is landfill capping and why is it important?
A landfill is a controlled structure designed to safely store municipal, industrial, and construction waste over the long term. Landfills are man-made structures that can be formed in depressions, above-ground fills, and canyons to reduce the release of harmful material.
Modern landfills are more advanced and focus on engineered systems for long-term management of landfill gases, primarily methane, through collection and treatment or energy recovery. Such systems include the protection of the groundwater and the control of the leachate collection systems by the use of clay and geosynthetic liners. Moreover, the collection of methane by gas collection systems helps in managing the waste.
What is landfill capping?
The landfill capping process entails covering a landfill with a barrier designed to limit environmental exposure, control gas and water movement, and support post-closure land use. The barrier can be made of materials such as soil, geosynthetics, or vegetation, among others. Proper sealing marks the end of a landfill’s (or a landfill cell’s) operational life. This process is crucial for safe, long-term, post-closure performance while ensuring minimum threat to the surrounding environment.
Why is landfill capping important?
Landfill solutions:
One significant advantage of capping a landfill is its effectiveness in preventing water infiltration, which consequently halts leachate formation and safeguards groundwater from pollution.
By limiting the rainwater that can penetrate the waste, the cap decreases the rate of leachate production, thereby reducing the potential for soil contamination and ensuring the protection of surrounding water sources.
A properly built cap also reduces methane and other harmful gas emissions. Capping systems limit uncontrolled gas emissions, while integrated gas collection and venting layers safely capture methane for flaring or energy use which is important since methane is a powerful greenhouse gas contributing to global warming.
Prevention of leachate generation:
Leachate production is minimized through proper capping systems that prevent rainwater infiltration and reduce percolation through the waste mass, thus reducing the possibility of groundwater contamination. By isolating the waste from the external environment, landfill caps protect water resources and maintain ecological balance.
Gas management:
Good capping helps control landfill gas emissions. This includes methane that can cause explosions as well as contribute to global warming. Some landfill solutions, like those using StrataDrain™, enable methane capture for flaring or energy use.
Safety and public health:
Effective sealing enhances safety and public health by keeping waste out of direct contact, reducing the risk of disease and pest transmission. Capping also minimizes exposure for nearby communities by containing harmful materials and limiting emissions to safe levels
Land restoration and reclamation:
Capped landfills can be reclaimed for other purposes, such as recreational parks or commercial developments, which allows for land restoration and reclamation. This way, dangerous sites within communities are converted into productive land that enhances community value, improves aesthetics, and supports economic redevelopment.
Erosion control and land stability:
The cap itself, particularly when vegetated, is a primary method for controlling soil erosion on the landfill surface. This is essential for its long-term integrity. Erosion control and stability are especially important in areas with heavy rainfall or seismic activity. In such conditions, landfill caps that aren’t properly compacted or well-drained face a higher risk of failure.
Long- term cost saving:
The right kind of landfill capping solutions reduces long-term maintenance costs and increases the longevity of the containment system. Since repairing landfills is an environmentally sensitive task, ensuring that we have the best solution for the long term makes more budgetary sense for municipalities.
Sustainable waste management:
Even with growing recycling efforts, a large share of municipal waste still ends up in landfills. But with the right systems in place, these sites don’t have to go to waste. Collecting landfill gas-chiefly methane can change a dilemma into a resourceful opportunity. Depending on the site’s circumstances, the gas is either flared or converted into energy. When it is recovered for energy production, it supplements a city’s renewable energy resources and gives landfills a more advantageous function. This is supported by geosynthetic gas venting layers such as StrataDrain™, which facilitate the safe dissipation of landfill gases and can be integrated with methane collection systems for treatment or energy recovery.
Methods of landfill capping
Soil covers:
Traditional soil covers are made by compacting local soil to form a barrier that prevents water from penetrating the waste below. Using nearby soil helps keep costs low. However, these covers require regular attention since weather conditions and waste settlement can cause damage over time.
Geosynthetic covers:
Materials like geomembranes, geotextiles, GCLs, and drainage geocomposites block water, control gas movement, and improve slope stability. Compared to thick soil or gravel layers, geosynthetics offer higher strength, lower permeability, and more reliable drainage-making them ideal for long-term landfill covers.
Vegetative covers:
Vegetation planted over the landfill cover helps protect against wind and water erosion while improving how the site looks. By absorbing rainfall and reducing surface runoff, it adds an extra layer of protection. Vegetative covers also support local plants and animals, bringing ecological value back to the area. But extra care is needed to avoid deep-rooting species that could puncture geomembranes.
Contribution of Strata Geosystems in the landfill sector
We specialize in manufacturing and supplying geosynthetic materials to improve landfill performance and environmental safety. Our expertise in landfill management comes from building systems to expand, manage, and cap landfills –for all 3 different uses. The landfill sector:
MSE berms for vertical expansion:
The MSE berms enable vertical expansion of existing landfills, thus minimizing the need for new sites and at the same time optimizing land use.
Landfill drainage solutions:
Products such as StrataDrain are used in landfill systems to manage leachate and gas, supporting both environmental protection and operational efficiency.
Advanced capping solutions:
By utilising geosynthetic materials like StrataDrain™, StrataTex HSR™, and StrataGrid™, we offer durable and efficient capping systems that reduce water infiltration into the waste mass and limit the uncontrolled release of landfill gases.
Erosion control:
Our geosynthetic products control erosion at landfill sites, keeping slopes stable over time and protecting the environment from damage.
Access roads:
We also help build long-lasting access roads on landfill sites, which makes transportation and operations safer and more efficient.
Veneer stability:
Veneer stability refers to the resistance of soil cover layers placed over landfill liner systems, particularly on slopes. On steep slopes, soil cover can be prone to sliding, especially over smooth liner systems. Reinforcement using geogrids, along with confinement provided by geocells, helps stabilise the slope by increasing shear resistance and reducing downslope movement. These systems offer the necessary support in situations where unreinforced soil may not provide adequate stability or protection for the underlying liner.
Why come to Strata for landfill work?
Strata Geosystems brings technical depth and site-tested innovation to landfill engineering. Our experience spans complex sites in India and overseas where standard solutions were not viable.
Case: Vertical expansion at Vapi, Gujarat
We built India’s first vertical landfill containment with StrataGrid™ and StrataBlock™ because we didn’t have enough space. This solution increased waste capacity by 260,000 m³ in a small area without the need to buy new land. Geosynthetics wrapped around soil bags were used to stabilize the steep 70° inner slopes. Precast concrete blocks were used for the outer facings. The project also addressed greening over geomembrane using StrataWeb®, enabling successful slope vegetation.
Case: Capping and slope stability at Ghazipur, Delhi
At Ghazipur, we worked under a six-week timeline to stabilise steep slopes with geomembrane surfaces. Using StrataWeb® and StrataGrid™, we confined the infill soil, minimised erosion, and created conditions for turfing. This approach allowed for quick project completion while ensuring long-term veneer stability and erosion protection.
Case: Villena landfill, Spain
For capping and gas management, we supplied StrataDrain™ to replace traditional gravel layers. This geocomposite layer reduced installation time, simplified logistics, and improved gas venting and drainage efficiency.
StrataWeb® and StrataGrid™ used for landfill slope stability in Ghazipur, Delhi.
The main challenge was stabilizing a sufficiently thick soil cover over the sloped geomembrane to create a stable final surface and prevent erosion. The project had strict deadlines, requiring the design, supply, and execution to be completed within six weeks.
Solution
To stabilise the landfill slope, Strata Geosystems used StrataGrid and StrataWeb. StrataWeb held the fill material in place on the slope, which helped control erosion and gave vegetation a chance to grow. The vegetation added extra protection to the surface over time. This approach kept the slopes stable and intact, all while helping the team stay on track with tight project deadlines.
Strata Geosystems completed a landfill capping solution at Ghazipur within a demanding six-week timeframe. Additionally, we have developed systems for the Villena landfill in Spain and India’s first vertical landfill located in Vapi, Gujarat. These projects confronted essential issues including leachate control, gas management, and slope stability.
Reach out to us at Strata Geosystems. We’re here to help you find the right solutions for your needs. Visit our website or give us a call at +91 2240635100 or click here to start a conversation with our experts. Let’s work together to create a more sustainable future for your landfill projects.