Estimating Geosynthetic Performance in Severe Climate Conditions

Creating effective defenses against flooding, land- and mudslides, erosion, and more is of paramount importance. Geosynthetics play a vital role toward the creation of these defenses as products for filtration and water impermeability. In this article, we discuss some ways you can better estimate how a geosynthetic product will perform under extreme conditions as well as how to work with these products while exposed to the elements.

Designing a better drainage system against severe weather

There are a host of reasons why severe weather is a costly and dangerous climate event. One of the most harmful, long-term outcomes of severe weather is the potential for the damaging effects of heavy run-off to leach out contaminants in landfilled waste and seep into groundwater—often local community water supply.

Geosynthetics serving as the cover system for waste containment units (WMU) must be able to prevent water from penetrating the WMU. For the cover system to work well, it must use professionally sourced resins (often high-density polyethylene) made with minimal additives. Higher quality resins will produce a higher quality geosynthetic liner. These manufactured liners are so durable that they can be coextruded with surface texturing and features during production.

A studded upward-facing surface is one of the effective ways to help direct the flow of fluids that have penetrated the cover soil. The water funnels through these studs toward the fluid collecting system, preventing a build-up of water that—over time—could cause failure of any overlying soil component in the cover system.

Key metrics:

• Material quality and type of resin
• Durability and flexibility
• A complementing drainage system.

Increasing slope stability to prevent land- and mudslides

The rainy season also brings concerns over landslides and mudslides. While most Americans do not live near a landfill, in other parts of the world slope failures have had fatal consequences to neighboring residential areas and affect large populations through contaminated drinking water. In general, geotechnical concerns with an active landfill are about global stability while a capped landfill is more concerned about designing against cover system veneer failures.

Global stability involves the internal failure of the waste mass, sometimes involving the base liner system as the failure plane so the interface shear strength of the geomembrane is vital. Heavy rain and a disproportionate amount of pore water within the waste mass can affect global stability by essentially eliminating effective stress in the waste.  Capping a landfill or even installing a temporary cover can help reduce these slope failure mechanisms.

Veneer stability, on the other hand, refers to the liner’s slope stability. The steepness of the slope, the interface shear strength at low normal loads among the geosynthetics used in the design, and landfill gas management all affect veneer stability. Products like AGRU’s Super Gripnet feature consistent textured grips on the underside, making it the material of choice for superior interface shear strength in containment applications with steep sideslopes. Combined with the other environmental controls available with this system, the ClosureTurf Final Cover System provides the best solution for long term site closure with minimal headaches.

Key metrics:

• Material quality and type of resin
• Consistent asperity height and density
• A complementing drainage system.

Utilizing synthetic turf to get ahead of erosion

Heavy weather events like hurricanes test even the best designed landfill caps. Sometimes, there is not enough time for vegetation to grow and take hold before the stormy season. Insufficient vegetation in the subgrade leads to erosion and slope failure. One solution is to implement a synthetic turf.

ClosureTurf is a patented final cover system comprising AGRU’s Super Gripnet, MicroDrain, or MicroSpike geomembrane overlain by an engineered synthetic turf and specified infill material. It is a proven hybrid composite closure system that outperforms traditional closure methodologies and is the only system that gives a tested, hence predictable level of performance when subjected to severe weather conditions that occur in a post-closure timeframe. Installed above the geomembrane liners is the engineered synthetic turf, which offers robust erosion control in addition to a clean, aesthetic finish.

Key performance metrics:

• Material quality and type of geosynthetic resin
• Durability and flexibility of the liner components
• A complementing drainage system.

Working with geosynthetics in extreme climates

Under our current climate conditions, it pays to design with geosynthetics in mind. Whether you are planning a landfill closure, a new tunnel, or a containment cell, geosynthetics contributes toward the success of the project as an impermeable barrier against water or to funnel water toward a drainage system.