The document discusses different types of landfill liners used to prevent leachate from contaminating groundwater. It describes single liner systems using clay or geomembrane, single composite liners using two layers like clay and geomembrane, and double composite liners for hazardous waste with two complete liner systems separated by a drainage layer. Key liner materials discussed are clay, geomembranes, geotextiles, geonets and geogrids. Construction and sealing of clay and geomembrane liners is also outlined.

1. BY
S.Y.SUGADEV
M.TAMILSELVAN

2. LANDFILL LINERS
•It is provided to prevent the flow of lechate
into the ground water
•Liners are provide both at the bottom and
the sides of the landfill
•The landfill liner materials are
Clay
Geo-Membrane
Geo-Textiles
Geonet
Geogrid

3. •The design of liner depends upon the
characteristics of lechate and its rate of generation
•The liner systems are provided in the landfill sites
are three types
Single liner system
Single composite liner system
Double composite liner system
SINGLE LINER SYSTEM
 Only one membrane of impermeable
material is providedto control the flow of lechate
into the ground or sides of the wall

4. These type of liners are used for Non-
Hazardous,Nonreactive,and Non biodegrable wastes
and also where water table is deep
The majorly used liner material is Clay or Amended
soil
Sometimes Geomembrane is also used as a lining
material

5. SINGLE COMPOSITE LINER
 It comprises of two or more layers of
impermeable materials
Generally,geomembrane underlain by a
layer of clay is provided in this system
This type of liner system is mainy suitable
for Municipal Solid Wastes landfill sites
The combination of material is either Clay
and geomebrane, Geobentonite and
Geomembrane

7. DOUBLE COMPOSITE LINER
This system is provided for hazardous wastes
landfill sites
In this system two different liners are provided
one over the other with a sand layer sandwiched in
between
Each liner consists of a layer of clay and a layer of
geomembrane
The sand layer is provided with a network of
pipes to collect any stray lechate infiltering into it
from the upper liner

9. Requirements of landfill liners
It should be prevent migratiom of lechate or
landfill gas to the subsurface soil or ground
water
Liner material should have adequate resistance
to damage due to vehicular movement,climatic
conditions or chemical reactions with the wastes
It should be installed both at the base and
around sides of the landfill to the soils on all
sides

10. MATERIALS USED IN LINERS
These are generally constructed with naturally
available materials
Soil containing a high friction of clay are commonly
used
Synthetic liners made from plastics are also effective
due to their low permeability and also high durability
Various materials are used for liners.They are
 Soil/Clay
Geo-Membrane
Geo-Textiles
Geonet
Geogrid


11. Soil/clay
Among the soil liners clay liners are considered to
be a very effective for landfills
Clay is a soil which has grain size smaller than
0.002mm and exhibits cohesion
It is suitable not only due to its low permeability
but also for its potential of attenuationgthe
contaminates in lechate
Clay liners,1 mm thick usually,have permeability
as low as 10^-7 cm/s.At sites where clay is not
locally available,amended soil is used I landfill
liners

12. CONSTRUCTION OF SOIL LINERS
A common problem in the construction of clay
liners is the formation of cracks
The soil not to be allowes to dry out during its
placement
Such liners should be laid in thin layers,about
10 to 15 cm thick
Each layer should be properly compacted
using a heavy roller throgh several passes

14. GEOTEXTILES
These are used as filters in landfills in order to prevent
the movement of soil particles into drainage system
Due to their high permeability they allow the movement
of liquid while preventing the movement of adjacent soil
particles
They also act as a cushion to protect the geomembrane
liners

15. GEOMEMBRANE
It is a flexible sheet of polymeric material
and I s virtually impermeable
The most commonly used geomembrane is
made of high density polyethylene
Geomembrane liners are generally provided
along with the clay
The HDPE membranes are hugely in
demand because of their environmental
friendly characteristics.

16.  These properties have made the HDPE
geomembrane a standard choice to water-resistant,
covered landfills and various containment uses.
HDPE is one of the most comprehensively and
commonly used geomembranes in the world due to
its easy availability and reasonability.
HDPE geomembrane is certainly an excellent
product for large applications that require UV and
Ozone resistance, chemical resistance or high-
quality installations.

17. CONSTRUCTION OF GEOMEMBRANE
LINERS
Geomembranes are available in the form of rolls
of about 6.5 m widthand 150m length
These rolls should be properly seamed while
laying in the landfills by hot wedge
fusion,extrusion,or by solventadhesives
Sufficient overlap shold be provided at joints
Seaming should be avoided at locations where a
lechate head of more than 1m is expected

18. The following precautions must be taken while
installing a geomembrane liner
 laying of synthetic geomembrane should be
avoided during strong winds
 Large size particles should be removed before
insatllaing the geomembrane
 Movement of heavy vehicles should not be
allowed on the geomembrane during its laying
 geomembrene should be covered as soon as
possiblewith a sand layer of 20-30 cm thickness

19. SEAMING OF GEOMEMBRANE
The seaming of geomembranes can be
carried out in a number of ways for ex:
Thermal seaming,chemical seaming,fusion
welding

20. THERMAL SEAMING
This is suitable for geomembranes whicha
are manufactured with the base material
which is sensitive to heat
Seaming is carried out at a temperature of
more than 260 degree celsius
CHEMICAL SEAMING
IT IS CARRIED OUT BY USING VARIOUS CHEMICAL
AND BASE MATERIALS
The selection of chemicals used for this purpose
depends on composition of geomembrane

21. FUSION WELDING
This method is used only on HDPE LINERS AND
REQUIRES A HOT BASE PRODUCT
Specialized welders are used to extrude a ribbon
of molten HPDE which melts and bonds to the two
HPDE sheets to form a weld