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Drainage of landfill

Ground and wall drainage


Geonets and geocomposites are now used in a wide range of applications on controlled landfills, providing mechanical protection to geomembranes, gas drainage, collection and drainage of leachate and other liquids in the ground, as well as a barrier against capillary action.


Drainage systems for leachate collection and removal serve to limit the hydraulic head within the drainage layer.


The use of geocomposites to capture and gather leachate or other liquids entails both technical and practical benefits, in comparison to granular materials (aggregate) they are readily available and easy to install, they confer major stability to the slopes they are laid on, and exhibit considerable chemical resistance and excellent erosion/ corrosion resistance.


Synthetic geocomposites also provide real economic advantages if we compare their purchase price and installation costs to those of a traditional drainage system made up of layers of sand and gravel.


The minimal thickness of the geosynthetic layers and the possibility of building landfills with steeper slopes also allow to increase landfill capacity as more usable volume is available for waste storage.


The estimate of average cost savings is approximately 50% when using a synthetic product instead of a traditional one.




Municipal Solid Waste Landfill

Municipal Solid Waste Landfill

Municipal Solid Waste Landfill
Grotte San Giorgio (CT), Italy


Collection and removal of leachate in landfills


The leachate collection and removal system (LCRS) is usually installed on top of the primary liner layer inside the landfill.


TENAX TENDRAIN is a geocomposite consisting of a drainage core with three overlapping intersecting strands, especially designed for the drainage and collection of the leachate (LCRS).


The inner strands, the thickest and heaviest ones, provide a very high transmissivity and resistance to load compression while the cross strands prevent intrusion of the geotextile and the soil under sustained normal load which would otherwise cause clogging in the flow channels of the system.


TENAX TENDRAIN assures the collection and removal of the leachate under heavy compressive loads while maintaining constant hydraulic performance over a long period to limit hydraulic head within the drainage layer, in contrast to traditional geocomposites that may show a reduction in draining capacity due to compressive creep as a result of sustained normal load and to intrusion of the geotextile inside the geocomposite.




Leak Detection Function in Landfills


The leak detection system (LDS) is installed between the primary and the secondary liner. A leak detection system must:

  • provide rapid detection of major breaches in the primary lining system (within less than 24 hours);
  • limit the hydraulic head acting on the secondary barrier/layer to less than its thickness;

TENAX GNT high flow triplanar geonets provide the most efficient results for a rapid detection of leaks in the liner system. The high transmissivity of TENAX Geonets allows for a rapid collection and discharge of all liquids to the leachate collection sumps, thus minimizing the time between breach and leak occurrence and its detection.





TENAX CE, GNT, NDP geonets and TENAX TENDRAIN, TN and TNT geocomposites are easy to install, readily available, and totally inert to chemicals; these are some of the features that make each product a top solution for controlled landfills:

  • if installed beneath the geomembrane they prevent mechanical damage and drain fluids and gases from the soil;
  • installed between two layers of geomembranes in a double lining system they help leachate drainage;
  • used on top of the geomembrane they provide mechanical protection and help with leachate drainage.

Due to their high transmissivity they are safe and efficient substitutes for granular materials as foreseen by current legislation in force. The net capacity available for waste disposal will increase considerably by using TENAX geonets and geocomposites allowing much steeper slopes with increased slope stability in comparison to a traditional mineral drainage layer.




site for inert waste, bottom liner system: geosynthetics design solution



site for non hazardous waste: geosynthetics design solution



site for hazardous waste: geosynthetics design solution landfill - conventional design and design with geosynthetics

TENAX Drainage systems
and Geocomposites


TENAX drainage systems and geocomposites


Do you need high adhesion of the drainage/impermeable geomembrane interface?

TENAX HF High Friction geocomposites

> 40° interface friction


Are pressures moderate but rainfall considerable?

TENAX HD High Drainage Geocomposite

> 2 litres/m/sec under 20 kPa pressure


Do you require high hydraulic performance under high pressure?

TENAX TENDRAIN triplanar geocomposites tested at over 500 kPa normal pressure and

TENAX GNT geonets


Do you need to "confine" 100-150 mm
of unconsolidated material on steep slopes?

TENAX TENWEB hydraulically connected
confinement geocells


Do you need to keep 1 m of soil on the capping with the guarantee of suitable safety factors ??

TENAX MULTIMAT R "gripping" and reinforced 3D Geomats


Is a traditional geocomposite good enough
and do you want to cut down on spending?

TENAX CE geonets

TENAX TN filter/drainage geocomposite

TENAX TNT filter/drainage geocomposite

25 years of references all over the world








Landifll Leachate Collection and Removal System (LCRS)

Landfill Leak Detection System (LDS)





Landfill and contaminated sites

View/donwload the brochure:

Landfill and contaminated sites

Capping and remediation of contaminated sites


The TENAX drainage geocomposites in the landfill cover system limit the infiltration of water inside the landfill. This eliminates the possibility of water flowing over the membrane, reducing the soil/membrane friction coefficient to practically zero which in turn would cause sliding of the cover soil over the waterproofing cover layer.


Installation of the Geocomposite for biogas drainage in landfill

Installation of the Geocomposite for biogas drainage


Installation of the Geosynthetic Clay Liner or Geomembrane in landfill

Installation of the Geosynthetic Clay Liner or Geomembrane


Installation of the Geocomposite for drainage of infiltrating rain water in landfill

Installation of the Geocomposite for drainage of infiltrating rain water


Laying of the gripping and reinforced 3D Geomat in landfill

Laying of the "gripping" and reinforced 3D Geomat


Anchorage of the complete covering system in appropriate anchor trenches, if necessary filled with concrete

Anchorage of the complete covering system in anchor trenches


Spreading of the upper layer of vegetative soil cover

Spreading of the upper layer of vegetative soil cover


Hydroseeding or seeding

Completed with hydroseeding or normal seeding


Collection and disposal of surface water


If percolating water is not appropriately drained and water is allowed to flow through the cover soil it will gather on top of the impermeable liner causing dangerous conditions.


The extremely high hydraulic head caused by inadequate drainage can bring about catastrophic cover soil failure; in fact, numerous failures in landfills triggered by infiltration have been recorded and analysed.


TENAX drainage geocomposites that are correctly designed and installed on top of the impermeable layers, provide a guaranteed method for disposal of the total amount of precipitation that would filter through the vegetative soil cover.




Capturing biogas


The stability of the cover soil can be considerably reduced by pressures produced by biogas built-up beneath the capping layers (geomembranes or GCL’s) until failure occurs.


According to recent research on the transmission rate of gas and based on the theory of intrinsic permeability, the transmissivity of LFG (landfill gas) results to be ten times lower than the hydraulic transmissivity ratio in any porous medium.


This means that, to drain biogas, drainage layers with a high hydraulic capacity are required.




Surface erosion control and cover soil stabilisation


One of the major problems that arise during the design and construction of a permanent landfill covering system (capping) is how to keep a sufficiently thick layer of topsoil on slopes to permit the creation of lasting vegetative growth.


As a matter of fact, the angle of friction at the interface between the impermeable layer and the vegetative cover soil has usually very low values, insufficient to prevent the sliding of topsoil, even on shallow slopes.


The problem is furthermore enhanced by the need to carry out checks that prove compliance to the new technical regulations for landfill construction.

The use of a suitable geosynthetic material is therefore essential to convey to the covering soil the properties required to confer stability.


TENAX MULTIMAT R reinforced geomats allow the retention of vegetative material to a significant depth due to their three-dimensional structure and “gripping effect”, even on very steep slopes; after placing the mats immediately above the waterproofing layer (or, in case, on top of a geocomposite with filter- drainage functions for meteoric water) and firmly anchoring them at the top (in anchor trenches or by re-filling with appropriate material) and pegging into place on the slopes (using apposite large-head pegs), TENAX MULTIMAT R is successively “filled” with an abundant amount of slightly compacted vegetative soil.


Another way of “capping”, consists of the use of TENAX TENWEB geocells that allow the containment and stabilisation of vegetative soil into depths ranging from 7.5 to 10 cm, according to the type of geocell adopted, with the possibility of overlapping the geocells in several layers.






For the permanent capping of controlled waste landfills and the remediation of contaminated sites, TENAX has developed, in addition to its well established range of TENAX TENDRAIN and TNT geocomposites providing filter/drainage protection, a new range of TENAX HF High Friction and TENAX HD High Drainage Geocomposites:

  • TENAX HF (High Friction) Geocomposites exhibit high performance in terms of resistance at the geonet/impermeable membrane interface;
  • TENAX HD (High Drainage) Geocomposites can guarantee high performance in terms of flow rate and tensile strength.


landfill for inert waste disposal - geosynthetics design solution


site for non hazardous waste capping - geosynthetics design solution


site for hazardous waste capping - geosynthetics design solution landfill - conventional design and design with geosynthetics

landfill in Cerro Maggiore

Landfill in Cerro Maggiore, Italy


Containment of expanded clay on top of the modified capping system of the Modena Landfill

Containment of expanded clay
on top of the modified capping
system of the Modena Landfill


La Glacier Veolia landfill (France): capping system with High Friction drainage layer for meteoric water

La Glacier Veolia landfill (France):
capping system with High Friction
drainage layer for meteoric water








Landfill Surface Water Collection and Removal System (SWCRS)

Landfill Gas Venting (LFG)


Erosion control

Landfill capping



To increase the usable volume of a landfill two types of action can be taken basically: the construction of reinforced embankments acting as confinement barriers or retaining walls at the base, and the insertion of geosynthetics directly inside the waste mass, thus building an embankment of reinforced solid urban waste.



Confinement barrier and raised  embankment in the ARPA 1 landfill

Confinement barrier and raised
embankment in the ARPA 1 landfill
of Colleferro (RM), Italy


Confinement barriers in landfill and reinforcement for municipal waste disposal sites


The construction of Reinforced Soil Embankments with TENAX mono oriented geogrids provides extremely reduced cross sections in comparison to the non-reinforced ones, an increase in usable volume for waste disposal and, consequently, a reduction in the amount of land required for the construction of embankments.


This technology is now commonly adopted, as it does not present any particular problems from the point of view of design: the calculation models are standard for reinforced embankments while waste volumes are merely involved as a thrusting force behind the structure.


By applying the technology for Reinforced Soil Embankments directly on Municipal Waste Disposal sites, the usable volume available for waste disposal would be even more, with lower construction costs.





The TENAX RIVEL integrated System for reinforced embankments features the use of TENAX mono-oriented integral HDPE geogrids as reinforcing elements.


Thanks to the TENAX RIVEL System it has become possible to build extremely resistant reinforced embankments that can be constructed as edge embankments of minimum overall dimensions, providing an increase in landfill capacity volumes.


The TENAX RIVEL structures are designed to withstand both static load stress caused by the mass of waste as well as potential seismic accelerations for the area.

Nent landfill, Hong Kong

NENT, Hong Kong


Landfill perimeter confinement barrier

Landfill perimeter confinement
barrier in Villaputzu (CA), Italy




Soil reinforcement

Containment embankments and reinforcement for waste landfill

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