1. Ground Improvement Tehnique: Issues, Methods and their Selection
Dr. J.N.Jha,
Professor and Head (Civil Engineering),
Guru Nanak Dev Engineering College, Ludhiana, Punjab

2. Present Day Scenario
Best buildable lands not available for construction
Available sites are having low strength because :
Filled up sites,
Low lying water logged,
Waste lands,
Creek lands with deep deposits of soft saturated marine clays
Another problem: Design loads are high and the site is situated in seismic zones

3. What are the options?
Traditional foundation techniques sometimes costlier than the super structure and in many situations can’t be built
when a poor ground exists at the project site, designer faces following questions:
Should the poor ground be removed and replaced with a
more suitable material?
Should the weak ground be bypassed laterally by
changing the project’s location or vertically by the use of
deep foundations? or
Should the design of the facility (height, configuration,
etc) be changed to reflect the ground’s limitations?

4. Development of ground improvement, gives the designer/bulder has a fourth option
To “fix” the poor ground and make it suitable for the project’s needs
Now the designer/builder faces new questions:
Should the problematic ground at the project site be
fixed instead of bypassed?
What are the critical issues that influence the successful
application of a specific fixing tool? And
Which fixing tool to be used from comprehensive
and diversified set currently available in the tool box?

5. What are the major functions of Ground improvement in soil ?
To increase the bearing capacity
To control deformations and accelerate consolidation
To provide lateral stability
To form seepage cut-off and environmental control
To increase resistance to liquefaction
Above functions can be accomplished :
by modifying the ground’s character - with or without the addition of foreign material

6. The current state of the practice:
Densification
Consolidation
Weight reduction
Reinforcement
Chemical treatment
Thermal stabilization
Electrotreatment
Biotechnical stabilization

7. Ground Improvement by Densification
Methods of Application :
 Vibrocompaction
Dynamic Compaction
Blasting
Compaction Grouting
Key Issues affecting densification:
Percent of fines in the soil,
Ability of the soil to dissipate excess pore water pressure,
Energy felt by the soil,
Presence of boulders, utilities and adjacent structures, and
Mysterious phenomenon of ageing.

8. Vibrocompaction Loose granular soils are densified at depth by
insertion of vibrating probes into the ground
Compaction is achieved by impact and vibration,
Compaction is achieved by with or without the
use of a water jet or compressed air,
addition of granular material.
Densification can be achieved to up to 30 m in
depth

9. Schematic View and Equipment Used
Vibrofloatation
Schematic View and Equipment Used
1.Vibrofloat 2. Crane for Suspending Vibrofloat 3. Power Supplying Unit ( KW)

10. Real Time Photos

11. Vibrofloat
Nose Cone Lower Most Part helps in Penetration in to the soil Eccentric Weight Provides Weight, helps in lowering Vibrofloat Water Jet Creats a Quick Condition facilitating the vibrrofloat unit to sink Electric Motor Develops a huge Centrifugal Force by its Rotational Motion Vibration Insulator Prevents the vibration s to reach Hollow Tube Follow Tubes Facilitates the Vibrating Unit to Reach Desired Depth Diameter and Length Diameter mm Length- 2-3m.

12. Procedure-Step
Step-1-Jet at the bottom of Vibrofloat is turned on and is gradually lowered into the ground
Step-2- Water Jet creats a quick condition in the soil thus facilitating the vibrating unit to sink under its own weight

13. Step-3-Granular material is poured from the top into the hole through the annular space between the hole and vertical pipe. Water from the lower jet is transferred to the top of Vibrating unit which carries the granular material down to the hole.
Step-4- Vibrating unit is raised gradually in lifts (1 feet) and held for vibration for 30 seconds. This process is continued which compacts the soil to the desired density

15. Grain Size Distribution
Zone-B
Most suitable for Vibroflotation since Quick condition can easily be created
Zone – C and Zone –D
Contains excessive amount of Fines, Difficult to compact and requires considerable effort
Zone- A
Appreciable amount of Gravel, Compaction by Vibroflotation is uneconomical

16. Suitability of the Backfill
Suitability NumberSN = 1.7 {3/(D50)2 + 1/(D20)2 + 1/(D10)2}1/2
Where D50 ,D20 ,D10 are particle sizes corresponding to 10, 20 and 50 % finer of the backfill material
Range Of SN
Rating of the Backfill Material
0-10
Excellent
10-20
Good
20-30
Fair
30-50
Poor
>50
Unsuitable

17. Comparison of CPT Test
CPT Test Performed Before Densification of Sand Fills
CPT Test Performed After Densification of Sand Fills

18. Dynamic Compaction Repeated lifting and Dropping
of Weight at a location
Tamping Weight
(Concrete/Cast iron/Steel)-
80 to 120 kN
Ht. of Drop- 10 to 15m
No. of drops (same location)-
8 to 12 times
Formation of Crater like
Depression-Filled with Extra Soil
Process Repeated- Grid Pattern at
a spacing of 2-4 m
Densification of Soil- 4-8m below GL

19. In-Situ Dynamic Compaction

20. Blasting Weight of Charge(Rough Guideline)- W= 164CR3
W = Weight of Explosive (N)
C = Coefficient ( for 60% detonator)
R = Radius of influence (m)
Arrangement of Explosive- Grid Pattern
Firing Pattern – From outside to inside
First Blast- At the corner of Periphery Line of First Grid from outside
Second Blast – At the Centre of Periphery Line of First Grid from outside
Third Blast - At the corner of Periphery Line of Second Grid from outside
Spacing – 3 to 8 m (Less than 3 generally avoided)
Depth of Stratum to be densified – 10m or less
Depth of Explosive- 2/3 of depth
Compaction - In one tier only
Depth of Stratum to be densified – More than 10m
Depth of Charge – Greater than Radius of Sphere of Influence (R)
Compaction- More than one Tier

21. Materials & Equipments
Dynamite sticks.
Electric detonator.
Drilling equipment.
Backfill material (Sand).
Waterproof packets.

23. Method
Series of boreholes are drilled and Pipe of 7.5 to 10 cm is driven to the required depth
Dynamite sticks and detonator are wrapped in a water proof bundle and is lowered through casings
Casing is withdrawn and a wad of paper or wood is placed against the charge of Explosive (To protect it from misfire)
Boreholes are backfilled with sand to obtain full force of blast
Electric circuit is closed to fire the charge
The charge is fired in definite pattern
For deeper deposits blast is done in stages
Repeated shots are more affective than single larger one
Each successive blast in a given area will cause less densification than the one preceding
Top 1m surface get disturbed and needs surface compaction

25. Compaction Grouting Step -1 Predrilled Compaction Grouting hole to
desired depth
Step-2 Insert Compaction Grouting Casing in
Predrilled hole
Step-3 Begin Pumping Low Slump Compaction
Grout Mix in Stages and withdraw at
Controlled rate
Step-4 Withdraw casing as stages are complete
until the hole is complete

27. Key Issues Affecting Densification
Percent of fines in the soil,
Ability of the soil to dissipate excess pore water pressure,
Energy felt by the soil,
Presence of boulders, utilities and adjacent structures, and
Mysterious phenomenon of ageing.

28. Presence of Fines Fines act as lubricants reducing the frictional
resistance between the rearranged soil particles
of the densified mass.
In vibrocompaction, a fines content of 20
percent renders the process ineffective.
The amount of fines in the soil also affects
drainage properties
(A key factor when the densified soil is in a
saturated state)

29. Pore Pressure Dissipation
In a saturated cohesionless material, during
densification a micro- liquefaction process takes place
allowing the soil particles to rearrange themselves
If excessive fines or cohesive soils are present,
dissipation of the excess pore water pressure
generated by the densification process is slowed down
(or maybe prevented) thus affecting the feasibility of
the applied method

30. Level of Energy Factors affecting Level of Energy:
Characteristics of the equipment (Vibrating frequency, Tamper
weight, amount of explosives, etc)
Configurations of application (probe spacing, drop height, depth of
charge, etc)
Ground characteristics, effectiveness of the applied procedures and
the experience of the equipment operator
Degree of saturation and the way weight is dropped (a crane drop
is less efficient than a free drop)
Presence of soft cohesive layers or peat has a damping effect on
the dynamic forces penetrating the soil, and thus the depth of
influence is reduced

31. Proximity to Structures
The impact of the process 9 vibrocompaction or
dynamic compaction) on adjacent structures - A major
concern with no set criteria in present practice as to
how close can it be implemented next to an existing
structure
A recent project involving vibrocompaction of
hydraulic fill adjacent to a bulkhead structure:
Horizontal deflection less than 10 mm when the
vibroprobe was 3 m away from the bulkhead
Horizontal deflection increases to more than 50 mm as
the probe got within 2 m of the bulkhead

32. Ageing
Mechanism
Increase in strength and deformation modulus with time to the possible
action of silica bonding between grains
Rearrangement of the sand particles during secondary compression,
resulting in gradual increase in particles interlocking
Example Ageing:
Strength increase of 35% from the second to the sixth week after a
major vibrocompaction application in Hong Kong
On a recent project in Norfolk, Virginia, USA, a percent increase
in the relative density of a hydraulic fill, approximately 20 days after
vibrocompaction was measured due to ageing

33. Ground Improvement by Consolidation
Methods of application:
Preloading with or without vertical drains
Electro-osmosis
Vacuum consolidation

34. Preloading with or without vertical drains
Preloading is usually accomplished by placing surcharge fills
To accelerate consolidation, vertical (sand or prefabricated
wick) drains are often used with preloading

35. Principle and Mechanism
Coefficient of Surcharge: Ratio of
weight used in preloading and wt.
of the final structure to be
constructed on the improved soil
Using a surcharge higher than
work load, soil always remains in
an overconsolidated state
secondary compression for
overconsolidated soil is much
smaller than that of normally
consolidated soil
Increasing the time of temporary
overloading or size of the
overload, secondary settlement
can be reduced /eliminated.

36. Electro-osmosis The process of dewatering assisted by the application
of a direct electric current is known as electro-
osmosis thus resulting in consolidation
soft clays whose moisture content cannot be reduced by
conventional dewatering methods.
In Electro-osmosis method, Electrodes are installed in
the soil and a DC current supplied which results water
movement from anode to the cathode
A wellpoint system or ejector well system used as cathode which collects and removes the water from the ground.

37. Mechanism Electro-osmosis transports water of the clay pore space
to the cathodically charged electrode
When these cations move toward the cathode, they also bring water molecules along with them
These water molecules clump around the cations as a consequence of their dipolar nature
Macroscopic effect of this process is reduction of water content at anode and an increase in water content at the cathode
Free water appears at the interface between the clay and the cathode surface

38. Molybdenum Electrodes
Graphite Electrode
Metallic Electrodes
Shapes of Electrodes

39. Connecting Wires
Electrodes Before Installation
DC Current Source

40. Flow of Water under Electro-osmosis

41. Advantages and Limitations
Practical application limited since very costly.
Before actual application on site Laboratory tests and site tests are imperative.
Huge amount of electricity. needed
Highly skilled labour needed
Electrodes replacement needed from time to time.
Method becomes ineffective If the moisture content of the soil is extremely low
Can be used for dewatering of silty and clayey soils which are difficult to drain by gravity.
Method is fast and instantaneous.
Environment-friendly method
Equipments required are few in number and easy to carry to the site.
Method useful for all types of soils.
Efficiency of this method is very high.
Less man-power required to implement this method.

42. Vacuum consolidation Vacuum consolidation,
Both liquid and gas (water and air) are extracted from the
ground by suction
This Suction is induced by the creation of vacuum on the
ground surface and assisted by a system of vertical and
horizontal drains
Vacuum is applied to the pore phase in a sealed membrane
system
The vacuum causes water to drain out from the soil and
creates negative pore water pressure in the soil
This leads to an increase in effective stress to the magnitude
of the induced negative pore water pressure, without the
increase of total stress

43. For rapid pre-consolidation,
vertical drains (Prefabricated Vertical Drains) along with the vacuum preloading are used
Vertical drains helps to distribute the vacuum pressures to the deeper layers and drain out water from the sub soil
Vacuum preloading with PVD substantially reduces the lateral displacement and potential shear failure
Maximum achievable vacuum pressure in the field is only about 80kPa
Schematic view vacuum consolidation technique

44. Advantages of Vacuum preloading technique over the Surcharge preloading technique
Ground improvement with vacuum preloading does not require any fill material and there is no need of heavy machinery
Construction period is generally shorter
The increase in effective stress under vacuum preloading is isotropic. Therefore, the corresponding lateral displacement is in the inward direction and there is no risk of shear failure
Application of Vacuum Preloading improves Bearing capacity of soil by 100% in the case of soft clays and eliminates 70% of the total estimated settlement of design load
The overall cost of vacuum preloading is only about 2/3rd of that with surcharge preloading

45. Ground Improvement by Consolidation
Key Issues associated with consolidation:
Stability during surcharge placement,
Clogging of vertical drains, and
Maintenance of the vacuum.

46. System Stability
To safeguard against stability problems, the surcharge loads
are often placed in stages
Each stage of loading is added only after the soil has acquired
sufficient strength under the influence of the previous stage to
support the new load
Build up and dissipation of the excess pore water pressure and
the accompanying soil deformations are monitored to pinpoint
the time for stage placement
In case of electro-osmosis or vacuum consolidation no stability
problem is anticipated

47. Clogging of Drains
Clogging of the vertical drain is a key issue affecting the
feasibility of the system of ground improvement
Major advantage of the plastic wick drains over sand drains is
their flexibility and ability to sustain large deformations of the
consolidating cohesive soil, which may otherwise shear and clog
the sand drains, rendering them ineffective
The hydraulic conductivity of the wick drains is influenced by
the potential crimping of the material when large deformations
take place or clogging of the drainage channels due to an
ineffective filter jacket
A non-wooven geotextile fabric is usually used to provide
filtering and ensure the hydraulic conductivity of the
prefabricated drains

48. Maintenance of the Vacuum
Maintaining the vacuum by providing an all-around seal is
critical for the successful application of vacuum consolidation
Resistance of the membrane to tear during and after placement
is an important factor
Membrane is covered by a layer of soil or by water ponding to
prevent its tear by vehicles, animals or birds attacks, or
vandalism
Vacuum is generated by circulation of air through a series of
specially designed drains, installed to the depth of the layer to
be consolidated (new system developed recently in France
eliminated the need for the membrane)

49. Ground Improvement by Weight Reduction
Methods of Application:
Placing lightweight materials over the native
soil in one of three ways:
Spread in a loose form, then compacted
Cut in block forms, then stacked according to a
certain arrangement, or
Pumped in a flowable liquid form

50. Lightweight material used for ground improvement
Fill Material
Source/Process
Dry Unit Weight (kg/m3)
Wood fibers
Sawed lumber waste
550 – 960
Shredded tire
Mechanically cut tire chips
600 – 900
Clam shells
Dredged underwater deposits
1100 – 1200
Expanded shale
Vitrified shale or clay
600 – 1040
Fly ash
Residue of burned coal
1120 – 1400
Air-cooled slag
Blast furnace material
1100 – 1500
Flowable fill
Foaming agent in a concrete matrix
335 – 770
Geofoam
Block molded expanded polystyrene
12 – 32

51. key Issues (Weight Reduction Method)
Placement of the lightweight material,
Longevity and long-term performance

52. Material Placement When fly ash is wet during placement, it may become
spongy and difficult to compact; and when dry it may
become too dusty and environmentally unacceptable
Crushing and knitting of the shells during compaction,
and contamination of the shell embankment with the
generated fines, may significantly affect its gradation
and performance.

53. Longevity Flotation of the geofoam, its susceptibility to fire and to
deterioration from gasoline spills or insect borrowing, are long-
term longevity problems that require special measures
Continued crushing and knitting of the shells under the influence
of vehicular traffic may reduce the drainage potential of the
embankment resulting :
Ponding of water at the surface
May reduce the frictional angle of the material, thus, increasing
its lateral pressure on supporting structures

54. Ground Improvement by Chemical Treatment
Cement, lime, fly-ash, asphalt, silicate and others are used to
stabilize weak soils (bind the soil particles resulting in higher
strength and lower compressibility)
Lime stabilization, an ion exchange reduces the soil’s
plasticity and improves its workability. The ion exchange is
then followed by a chemical reaction that increases the shear
strength
In surface stabilization, the chemicals are mixed with the soil
and an appropriate amount of water, and then compacted
using conventional compaction equipment and procedures
In deep mixing methods chemicals are applied at depth by
injection

55. Methods of Application
Permeation grouting
Jet grouting
Deep soil mixing
Lime columns
Fracture grouting

56. Permeation grouting
Cement, lime, bentonite or chemical grouts (silicates, etc.) fill the voids in the soil to increase and cohesion and reduce permeability, with no change in the volume or structure of the original ground
Microfine cement grout is the latest addition to permeation grouting
Grout additives may be used to enhance penetrability and strength, and to control setting time
Grouting is performed by drilling holes in the ground and injecting slurry grouts through the end of a casing, or through specialized equipment such as a tube-a-manchette

57. Jet grouting Uses high-pressure fluids, applied through a
nozzle at the base of a drill pipe, to erode the
soil particles and mix them with cement grout as the drill bit is rotated and withdrawn, forming hard, impervious columns
The grouted columns can be formed vertically, horizontally or at an angle.
A row of overlapping columns forms a wall.
Jet Grouting is used mainly for excavation
support, underpinning, tunneling and
groundwater cut- off

58. Deep Soil Mixing
Technique consists of mixing in-place soils with cement grout
or other reagent slurries using multiple-axis augers and mixing
paddles to construct overlapping stabilized-soil columns
By arranging the columns in various configurations, the
system can be used for strengthening of weak soils, for
groundwater cut-off, or liquefaction control
When used for liquefaction control, the DSM system is
performed in a block or lattice pattern to resist the stress from
embankment or surcharge loading when loose cohesionless
soils liquefy during seismic ground shaking
If needed, steel reinforcement is inserted in the column to
provide bending resistance

60. Lime Columns
Lime columns method is a variation of deep soil mixing, in
which unslaked quicklime is used in lieu of, or mixed with, the
cement
The lime columns are suitable at best for stabilization of deep
soft clay deposits
A pozzolanic reaction takes place between the lime and the clay
minerals resulting in substantial increase in the strength and
reduction in the plasticity of the native material
The heat generated by hydration of the quicklime also reduces
the water content of the clayey soils, resulting in accelerated
consolidation and strength gain
Lime columns can be used for load support, stabilization of
natural and cut slopes, and as an excavation support system

61. Installation step of Lime Column

62. Protection of pile structure with lime column
Stabilisation of light structure with lime column
Stabilisation of cuts with lime column

63. Fracture grouting
Fracture grouting, is also known as Compensation Grouting.
It is the injection and hydro fracturing with grout
slurry of the soil between the foundation to be
controlled and the process causing the settlement
Grout slurry is forced into soil fractures, hence
causing an expansion to take place counteracting the settlement that occurs or producing a controlled heave of the foundation.
Multiple injections and multiple levels of fractures create a complementary reinforcement of the area.
Fracture grouting is used to increase the shear
strength so that the resultant bearing capacity could act as resistance of soils and to raise structures.
Fracture Grouting Applications
Elimination/Prevention of the settlement of buildings
Reduction or reversal of total settlement
Prevention of the settlement of tunnels
Reduction or reversal of differential settlement

64. Key Issues involved in Chemical Treatment
Soil-grout compatibility and reactivity,
Operational parameters,
Column verticality, and
Weathering effects

65. Soil-grout compatibility and reactivity
The type of grout used and the make-up of the grout mix are
dependent on the properties of the ground
In permeation grouting, the principal parameter affecting
permeation is the size of the intergranular voids, usually
represented by the soil’s coefficient of permeability
Success of jet grouting is influenced by ground characteristics
such as the size and frequency of boulders, and the presence of
peat or organic materials
In lime columns, the feasibility of stabilization and the amount
of lime needed for pozzolanic reaction are influenced by the
type of soil being treated

66. Operational parameters
All deep chemical treatment methods are operator-sensitive and
their success depends on operational parameters controlled by
the construction crew
Both the strength and the permeability of the treated mass are
influenced by
Net amount of cement in the ground (controlled volumes of
cement, water and additives mixed at the grout plant or at the
top of the deep mix auger)
By the level of the soil-grout mixing achieved in situ
In deep soil mixing, the grout flow is usually adjusted constantly to accommodate varying drill speeds in different soil strata
Diameter of the column is a function of operating parameters,
such as injection pressure, grout flow, and rod withdrawal and
rotation rates
In case of fracture grouting the grout mix is adjusted by the operator
to provide the required performance(performance-type specifications)

67. Column verticality
The verticality of the constructed column is an important issue in
jet grouting, particularly when used to construct fluid barriers
Multiple rows of overlapped columns are usually designed when
used for construction of a cut-off wall, on the basis of the
assumed permeability of the jet grouted column
When two adjacent columns deviate from their vertical
alignments in opposite directions, the required column
overlapping may not materialize, and voids may develop in the
jet grout wall rendering it ineffective as a cut-off wall
The verticality and overlapping of columns are less of an issue in
deep soil mixing since the columns are constructed to fixed
diameters and the overlapping is ensured by the construction
process

68. Weathering effects
Long-term behavior of the chemically-treated soil structure is
influenced by weathering, particularly if it is continuously
exposed to weathering elements such as water, wind or
temperature
Lime-treated soils absorb less water with time and also dry faster
Frost heave in lime-stabilized soils is more particularly if the
soils are frozen within one month after compaction
Resistance against frost-thaw effects, however, increases rapidly
with curing time as the strength of the stabilized soil is increased
Resistance of the chemically treated soils to weathering effects is
tested through durability tests involving wet-dry or freeze-thaw
cycles

69. Ground Improvement by Reinforcement
Methods of Application:
Mechanical stabilization
Soil nailing
Soil anchoring
Mirco piles
Stone columns
Fiber reinforcement
Key Issues Affecting Soil Reinforcement:
Load transfer to the reinforcing elements,
Failure surface of the reinforced soil mass,
Strain compatibility between the soil and the reinforcement,
Arrangement of the reinforcing elements,
Durability and long-term behavior of the reinforcements.

70. Ground Improvement by Thermal Stabilization
Methods of Application:
Ground freezing
Vitrification
Key Issues of thermal stabilization
Degree of saturation of the soil,
Rate of groundwater movement,
Creep potential of the frozen ground,
Post thawing behavior,
Heat transfer in the melted soil and
Impact of heat on utilities and adjacent structures.

71. Ground Improvement by Electrotreatment
Methods of Application:
Electrokinetic remediation
Electroheating
Electrokineting fencing
Bioelectrokinetic injection
Key Issues in Electrotreatment
Soil’s electrical conductivity,
Ionic characterization of the contaminants, and
Impact on buried objects and utilities

72. Ground Improvement by Biotechnical Stabilization
Methods of Application:
Brush layering
Contour wattling
Reed-trench layering
Brush matting
Live staking and others
key issues affecting biotechnical stabilization
Development of artificial cohesion in the ground,
Effects of evapotranspiration, and
Durability of the vegetation

73. Factors affecting the selection of a ground improvement method
Groundwater
Construction considerations including schedule, materials, accessibility, right-of- way, equipment and labor
(d) environmental concerns,
(e) durability, maintenance and operational requirements
(f) contracting, politics and tradition,
(g) cost

74. Thankyou

75. Waste Containment with Geosynthetics
Large quantities of waste are being produced
since 1990 due to Rapid industrialisation and
Excessive urbanisation
Waste needs to be disposed off and only disposal
bin is ground and it occupies large chunk of land.
One million ton of municipal solid waste
occupies approximately one million square meter
(One square kilometer of land area when waste is
spread uniformly with a thickness of one meter)

76. Other problem associated with waste disposal
Another problem with the disposal of waste :
Source of pollution
Contaminates the soil beneath the waste
Contaminates the ground water as
contaminants travel from the solid waste to
the subsurface environment

77. Other sources of subsurface contamination
Ponding or impoundment of Liquid Waste :
Slurry type liquid waste
Leakage from storage of liquids in underground
tanks
Leakage from pipelines that transport liquid
Accidental spills of toxic liquid
Application of fertilizers , pesticides on large
agricultural areas

78. How to tackle and minimise this damage
Design and implementation of solution for
detection, control, remediation and prevention of
subsurface contamination
Protection of uncontaminated land
Analysis of the fate of contaminants on and in
the ground including transportation through
geomedia
Use of waste material on and in the ground for
geotechnical construction

79. Pollution:MSW/ISW
Municipal solid waste/Industrial solid waste place on the
ground: two most significant source of subsurface
contamination
Water infiltrates into waste and reacts physically,
chemically and biologically to produce leachate
Leachate infiltrates into the ground causing subsoil and
ground water contamination
Solid waste continues to stay at the location where it is
placed for years
Therefore the process of leachate infiltration into
subsurface environment continues , slowly but surely for
several yearss

80. Control and Remediation
Clean up of soil involves - Treatment of three phases in soil:Solid soil particle, Liquid pore fluids and Pore gases
Methods
Controlling the spread of polluted zone by installing impermeable vertical barriers (cut-off walls) all around and horizontal cover above the contaminated site
Removing the source of contamination and placing it in designed facility
Excavating the affected soil, washing it or teating it and placing it back after treatment

81. Pumping out the contaminated ground water by using a
set of tube wells installed in the
Contaminated zone , treating the ground water and the
injecting the purified waterback (Pump and Treat
Method)
Pumping out pore gas from the unsaturated zone using
gas wells and allowing air to enter through injection
wells
Using micro-organism to biomediate the sub soil and
ground water by transforming or immobilzing the
contaminants
Using thermal treatment e.g. incineration

82. Control of subsurface contamination for new facility
For solid waste: Providing impermeable flexible liners at
the base and covers on top of all Solid waste disposal
facilities to minimize leachate formation
For slurry type waste: Providing storage in ponds and
impoundments having incrementally raised
embankments and impermeable flexible liners at the base
For liquid: providind storage in ponds with impermeable
flexible liner
For underground liquid storage facility: Providing
double walle tanks with leakage detention system placed
between the walls