How geogrids are used to create vertical landfills?
Geogrids, often overlooked but essential in the construction of efficient landfills, play a critical role. In this blog, we discuss the use of geogrids in vertical landfills, their benefits, and why Strata Geosystems has emerged as a global leader in optimizing landfill and waste management projects.
What is vertical landfill expansion?
As the name suggests, vertical expansion of landfills involves creating a new landfill above the existing site. In simpler terms, it refers to increasing the landfill’s capacity by building upward within the existing site boundary. These landfills, also known as piggyback landfills, have gained popularity due to their ability to maximize waste storage within the permitted land area. However, it’s crucial to remember that the key to their success is maintaining existing sites to maximize their utilization. This is particularly important because the load-bearing capacity tends to decrease as additional vertical layers are added to the landfill site. Factors such as slope stability, foundation support, leachate installation, waste management, and proper drainage installation need to be carefully considered.
Various techniques, each tailored to the specific site conditions and the layout of the existing landfill structure, can achieve vertical expansion of landfills. These techniques, including perimeter implementation, wall retention, and MSE perimeter berms, aim to maximize the airspace and ensure efficient waste storage.
Maximizing airspace often involves traditional methods of stabilizing the soil with concrete. However, with ongoing innovations, traditional concrete-based soil stabilization has been successfully replaced by geosynthetic materials like geogrids. This geomaterial is used in the design of MSE berms, where it reinforces the soil slope, enhances stability, and acts as a barrier.
What is the role of geogrid in creating a vertical landfill?
At Strata Geosystems, we deploy a geogrid layer to confine the soil cover layer, and provide it structural stability. With geogrids, the soil is reinforced, as a way of addressing veneer stability. This feature in design is a newer method of improving the structural integrity of the site, allowing for more waste to be added vertically.
One of the most essential techniques for vertical landfill expansion involves the use of Mechanically Stabilized Earth (MSE) berms. These berms create additional capacity on top of the existing landfill by forming a near-vertical retaining wall. The geogrid material is added to the retaining walls to create confinement, while providing vertical support to the structure. With vertical landfills, a berm works to create depth and elevation which adds more volume to the airspace allowing for expansion of the cells within the same area. By using geogrids to stabilize the berm, we ensure that the soil is stabilized so that it can withstand pressure from the newer waste, and the soil below doesn’t move, or get deformed with the additional pressure. With most older sites, the greater risk after gas leaks, and leachate leaks is from the waste site collapsing –this could mean a landfill landslide –which is quite dangerous. Therefore, depending on the site requirements, the berm would undergo reinforcement either laterally, by layering geogrids within the berm layers, or vertically. Geogrids prevent slippage of internal layers, by confining materials. This property means that the soil stays in place, and doesn’t move relatively when the site experiences higher pressure and load.
Why use geogrids for landfills?
- Soil reinforcement: Using geogrids considerably increases the load-bearing capacity of soil. They reinforce weak subgrades and improve resistance to surface deformation and localized ground movement. It provides stability to the soil, especially weak subgrades, and prevents any significant damage to the structure.
- Landfill construction: for the creation of a new site, at Strata Geosystems, we recommend adding a layer of geogrids within the structure itself in between the soil layer, and vegetative cap to ensure stability and load distribution.
- Erosion control: When the foundation is laid, if geogrids are installed, they prevent soil erosion by providing veneer stability. The grid-like aperture structure of geogrids locks in the soil, preventing it from erosion caused by wind, rain or any other natural reason. Additionally, adding vegetative layers on top allows for a green and pleasing fascia, if we further also add geocells.
- Stable foundation:The grid structure of geogrids helps confine soil, distribute loads more evenly, and improve the foundation’s stability and performance under load. By minimizing lateral soil movement, geogrids help prevent settlement, tilting, or slumping of the structure.
- Rapid construction: Unlike traditional methods of constructing landfills, geogrids offer rapid construction, as they are easy to install and do not require much labour for installation. It eliminates the necessary time taken to construct the walls and foundation.
- Economical choice: The installation of geogrids does not require much labour and is also directly transported to the construction site, this significantly eliminates the labour and construction costs, making it an economical choice.
Projects by Strata Geosystems
Case study 1:
Client: Modern landfill of Model City
Location: New York, USA
Product used: StrataGrid™
About the project:
A huge challenge was encountered in the Modern landfill of Model City. A high-pressure gas lining was running through this landfill site. The original plan was to move the gas line to meet the landfill capacity; however, this plan was quite expensive and time-consuming. Hence, it was decided that another option should be considered.
Strata Geosystems suggested using StrataGrid geogrid, as soil reinforcement. For primary reinforcement and strengthening of the soil, StrataGrid 350 and 500 were used. For secondary reinforcement, a lighter-weight StrataGrid 150 was used. This helped lift the primary reinforcement. With careful installation of multiple geogrids and soil layers, Mechanically Stabilized Earth (MSE) berms were constructed. Due to this, the capacity of the existing landfill site was also maintained without the requirement to shift the high-pressure gas line. This solution also resulted in being cost-effective and highly efficient.
Case study 2:
Client: Vapo Green Enviro Limited
Location: Vapi, Gujarat, India
Product used: StrataGrid™, StrataSlope™ and StrataBlock™
Application: Vertical expansion of existing cell for a landfill
About the project:
Vapo Green Enviro Limited, a landfill situated in Vapi, Gujarat, faced a shortage of storage space. Due to the unavailability of space and increasing cost concerns, horizontal expansion of the landfill was quite impossible.
Strata Geosystems came in with an innovative solution. We suggested using the airspace instead of landscape and constructing a vertical landfill. Theoretically the idea seemed to highly successful, however there were 3 challenges:
- Vertical expansion over existing embankments in some parts of the landfills.
- Proper soil reinforcement in steep slope areas.
- Enhancing the strength of the existing embankment with soil nails to provide support to reinforced soil.
These problems were successfully tackled by Strata Geosystems with their innovative geo-synthetic product StrataGrid. The inner slope was reinforced by StrataGrid along with two major systems StrataSlope and StrataBlock. StrataGrid acted as a wrap around the soil bags, preventing leachate problem and potential leakage. Vapi Green Enviro Limited was highly satisfied with this landmark solution provided by Strata Geosystems.
In a nutshell, geogrids are a vital component in modern construction, especially for soil reinforcement and stability. They play a significant role in constructing vertical landfills. These landfills utilize vertical airspace rather than expanding horizontally, creating more capacity within the same footprint while also containing leachate and harmful contaminants effectively.
Strata Geosystems’ StrataGrid geogrid has played a key role in the success of numerous vertical landfill projects worldwide. To know more about the services provided by Strata Geosystems or to get expert advice from their experts, get in touch with us!