Water Seepage Control through Novel Sheet Materials

Water Seepage Control
through Novel Sheet Materials
Prof. B L Deopura & Dr B R Chahar
Indian Institute of Technology,
Delhi
Partly Supported by Min. of Water Resources, Govt of India
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Outline
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Water Shortage Problems
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Current Solutions
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Technical Merits
Financial Feasibility
IIT Delhi Innovations
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Implications
Methodologies
Case Studies & Results
Applications
What the Future Holds
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Agriculture Economy
Indian economy grew by 9.1% during the
first half of the current fiscal. Riding on
better than expected performance by
industry and services. Agriculture,
however suffered despite not too bad
rains.
Times of India 1st December 2006
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The Problem of Water Availability
• Water
– Source: Precipitation
– Storage: Reservoirs, ponds, tanks
– Transport: Canals
• Seepage Loss
– Ponds(7cm/d to 50cm/d)
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Consequence of Water Loss
• Examples
• Rajasthan Canal
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Significant Water Loss
Large areas water logged
Contamination of ground water (salinity)
Seepage can flood neighboring areas
No water at tail-end
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Viable Solutions
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Why Traditional Solutions don’t work?
Cement/concrete cover
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Settlement of the soil below the cover material
Limited support of the wet soil
Thermal expansion /contraction
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Geomembranes
• Basics
– Sheet materials
– Impermeable to liquids
• Critical properties of the sheet materials:
– Extensible more than 25%
– Excellent puncture resistance
– High elastic deformations
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Lined Potable Water Reservoir
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Geomembrane protecting failed
subgrade
Failed sub
grade
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Canal Lining Example
Prior to Lining
After Lining
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Placing of Geomembrane
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Canal Lining Prineville, Oregon
Preconstruction condition
After completion of lining
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Example of Canal lining
Before
After
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Canal in use 18 years with
geomembrane
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Lining a Live Canal
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Typical Sheet Materials
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HDPE, High Density Polyethylene
HDPE
- Internationally accepted material
•
PVC, Poly Vinyl Chloride
PVC
-Limitations:
leaching of plasticizer, UV stability
•
LDPE, Low density polyethylene
LDPE
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Limitations:
Low puncture resistance, Ineffective
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Damaged LDPE Sheets
PVC with algae
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IITD Innovations
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Superior to commercially available materials
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International materials
Thickness (0.6 mm)
Innovation in developing composites
Comparison to current materials used:
Material
Thickness
(mm)
HDPE
Puncture
Strength
(Index), (kN)
Tensile Strength
at Break (kN/m)
2.0
0.5
50
0.6
0.5
55
1.5mm
IITD
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Prominent Case Studies
•
IARI, Indian Agricultural Research Institute, Delhi
•
IIT Delhi
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CARI, Central Agriculture Research Institute , Port
Blair
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Jalvardhini Pratisthan, - NGO Karjat,
Maharashtra
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Case Study 1: IARI, Delhi
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IARI
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IARI, Delhi
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IARI, Delhi
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Case Study 2: IIT, Delhi
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IIT, Delhi
Testing without lining
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IIT, Delhi
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IITS Sheet
IIT, Delhi
Stone pitching
Cement/concrete
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Observations at IITD
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Very high seepage observed in pond without
sheet material
After installation of sheet material, seepage
negligible even after three years of use
Sheet properties are nearly same after three years
of use
Different covers atop the sheet can be used
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Case Study 3: Pond at Karjat, Maharashtra
NGO Jalvardhini Pratisthan
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Karjat, Maharashtra
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A geomembrane lined
pond can be build to any
size and shape.
As shown in the
photograph, a tank of
size 5X3X1 m is
excavated , side is
smoothened, sheet is
laid.
To protect, the sheet is
covered with a suitable
cover say soil cover.
www.Jalvardhini.org
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Karjat, Maharashtra
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Case Study 4: WTCER, Bhubaneshwar
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WTCER, Bhubaneshwar
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Case Study5:Ponds at Port Blair
A GROUP
OF PONDS
IITD SHEETS
LDPE
SHEETS
WITHOUT
SHEETS
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PVC Sheet
Port Blair
IITD Sheet
PVC Sheet
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Limitations of HDPE
Geomembranes
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Large thicknesses of 1.5-2.0mm
High cost of transportation and installation
Widths limited to 5-8 m and thus failure prone
in large scale field sealing.
Field sealing is highly specialized job, high cost
HDPE is prone to stress-crack and thus ground
preparation must be well compacted and very
smooth; low tolerance to swelling soils.
soils
Elastic extension limited
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Advantages of IITD Innovation
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Large panels and thus reduced
field sealing
Field sealing easy
Long life of 30+ years
Low maintenance
Easy handling; Short time for making
the pond
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Advantages of IITD Innovation
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Thickness approx. 0.6mm
- Low cost of transportation and installation
- Take the ground counter easily
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Excellent Puncture resistance
- Equivalent to HDPE sheet of 1.5-2.0mm
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Not prone stress cracking
Extensions to 50% at break
Large elastic extension
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IITD Sheet Material Data
Property
Polymer Type
Test Method Units
----
Performance
(SI)
---
Polyolefin
Thickness
ASTM D5199
mm
0.5
Puncture Strength
ASTM D4833
kN
0.5
UV
Resistance
EN277
For 200hours
----
Pass
Breaking Strength
ASTM D638
Type IV
kN/m
36
Breaking
Elongation
ASTM D638
Type IV
%
35
Tear
Resistance
ASTM D5884
kN
0.20
Water Permeability
ASTM D1499
cm/sec
10-6
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Cost Calculations
Top View
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V= h[(x-2d) (y-2d) + d(x+y-2d)]
S= [(x-2d) (y-2d) + 2L(x+y-2d)]
C~ 400 [(x-2d) (y-2d) + 2L(x+y-2d)]
Assume:
X=20m; Y=20m;
h=3.2m; c=1.5;
d=hc=4.8m;
L=h (1+c2)-1/2 =5.8m
Cost/sq.m =Rs.400
Results: Volume
V=8.9 Lakh litres
Cost/litre=0.21
Side View
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Suggestions for Future
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The IITD sheet materials specifications included
in the standards of making the ponds.
Making of ponds using the sheet material is
initiated extensively.
Familiarizing the users through workshops
Making ponds at the laboratories for demo.
Ponds for farming, aquaculture, household and
industrial purposes.
Community farming methods for large size
ponds.
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Acknowledgements
We are thankful to Central Agriculture
Research Institute (CARI), Port Blair;
IARA, Delhi; WTCER, Bhubneshwar;
Jalvardhini Pratisthan, Karjat, Maharashtra
for their support in conducting the field
trials and making the observations available
to us for dissemination.
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Thanks
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Rectangular Pond
x
• Size of the pond be x y z in meters
• Volume of the pond V =X Y Z
• Cost of the Pond :
~ 250[(x+2z+1) (y+2z+1) + z(x+y)]
y
Let Size of the pond be 5, 3, 1 meters
• Volume of the pond 15,000 liter
• Cost of the pond
~ 250 · [(8) (6) + 1· (8)] = Rs14, 000
• Cost/liter = 14000/15000 ~ 1
z
Some Answer
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How do the rodents affect the geomembranes?
Rodents do not easily puncture the standard geomembranes
and thus do not affect them
Do you require a CNS layer while constructions over
swelling soils?
No, the soils are not allowed to swell by using these sheets as
cut off. This is the most economic solution, and sometimes
the only solution for constructions over expansive soils.
What is the water height the typical geomembranes (1.5
Thick HDPE) can sustain?
Typically 30meters, as these sheets are extensible under
water pressure
Are geomembrane very expensive?
Taken into account their long life, and huge savings of
water, the slight initial cost is recovered quickly. This also
makes water available which is otherwise lost in seepage.
Some Answers
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•
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What are the puncture resistance (ASTM D4833) values of
HDPE sheets of thickness (a)0.5mm (b )1.00mm?
The typical values in kN are (a ) 0.16 (b )0.32.
What are the tear resistance (ASTM D1004) values of HDPE
sheets of thickness (a)0.5mm (b )1.00mm?
The values in kN are (a ) 0.07 (b ) 0.14. These values may
vary slightly depending on the resin used.
What is the typical life expectancy of the geomembranes of
HDPE sheets of thickness 1.5mm?
Typical lifespan of these sheets is thirty years plus under
covered conditions. The life under exposed condition may
vary quite significantly and is typically ten years.
Conclusions
• Sheet can be placed on compacted soil
• Cover material such as bricks, cement
/concrete, stone pitching or soil.
• Cover thickness over the sheet material of
cement/concrete can be minimized.
• Lining can be done very quickly.
• Significant reduction in cost of Canal, Pond
construction/repairs with seepage control
• Low maintenance.
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HDPE sheet materials
• Susceptibility to stress cracking
• Thick sheets, limited
conformability
• Thicknesses lower than 1.5mm, low
puncture resistance
• Elaborate arrangements for
transportation and installation
• Flat over the soil, without folds
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HDPE Sheets Limitations
• HDPE and similar polyethylene based geomembranes are
available in limited widths of 5m to 9m and thus requires
extensive field sealing. This adds on the time for
implementation of the project.
• These materials are sensitive to temperature of weld and thus
trained manpower is needed for the field sealing.
• The deformation of HDPE beyond yield point is through
yielding. In case of uncontrolled deformation in actual field
conditions, the thinning may not be uniform across the width
of the sheet and may have areas of stress concentration
leading to failure. The useful deformation is thus limited to the
yield point i.e. around 5%, although the elongation at break
may be 500%.
• Effect of tangential stress combined with in planer stresses.
For tangential stress, if the material deforms beyond yield
then it continues to reduce in thickness till failure.
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IITD Sheet materials: Advantages
• As the thickness of these sheets is low, it is very ductile and has good
conformability with soil. A comparison of bending rigidity of sheets of
thickness of 1.5mm (say HDPE) to 0.6 mm will give a very high
multiplier factor of approximately 6.25.
• Being very low thickness, these sheets could be suitably folded for
transportation.
• Further, these sheets could be folded during the placement to take
care of the contours in the sub grade and could be maintained in the
fold shape indefinitely. This fact is particularly helpful in making a pond
from a flat sheet. The situation is helped by the fact that these sheets
have excellent stress crack resistance.
• These sheets could also be factory welded to fairly large dimensions
(say 100 x 50meters) thus reducing the field welding and thus superior
performance. Additional requirements of field welding of these sheets
could be met by standard heat wedge method. Further, this reduces
the time for implantation of the project.
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IITD Sheet materials: Advantages
• The installation is possible even if there is some water on
the bottom of the pond, as these sheets are not affected
by the presence of water.
• The project implementation time is significantly due to
easy handing of the sheets.
• The sheets could simply be used on the water face to
make a barrier using an earthen dam, which could be
executed in short duration. The stability of the structure
is enhanced due to water seepage control.
• There may be a possibility of live installation in cases
where dewatering is not practical.
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Applications in Reservoirs
Tyabb Reservoir's lining using 1.1mm flexible PP
geomembrane to provide a closed system of water
storage and supply
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Waster Water Lagoons
Floating covers constructed from reinforced flexible polypropylene
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Lined Potable Water Reservoir
Leak Detection
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Water Proofing in dams
Concrete Dam Leaking
Lining a concrete dam
Water Proofing in dams
Completed Concrete Dam Lining
Lined Earth Dam: Before Rip-Rap
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Geomembrane lined tunnels
Aquaculture
• Fish-farming is also big business
• Generally shallow gm-lined ponds
• Lining required for control purposes
(nutrition, oxygen, contamination)
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Aquaculture
Geomembrane Lined Shrimp Farm
Lots and Lots of farms
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Lots & Lots of Them!
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What does the future hold?
• Vision: Water should not be a scare
commodity
• Awareness: Water loss is the problem
• Goal is to drastically improve water availability
in rural/urban areas
• 5 years
– Line approx. 10,000 km of Indian canals (<5%)
– Line 100,000 medium to large size ponds
• Major drive interconnecting of rivers
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Field Trials 3
Water Technology Centre Eastern
Region (WTCER), Bhubaneshwar
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Field Trials 2
Indian institute of Technology, Delhi
• A pond of 5m x 3m x 2m
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Typical loss of water are (type of soil and seepage)
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Water seepage
Depending on the soil conditions
The civil structure may get damaged – cracks in the
cement /concrete cover
Typical losses in in the canal system may range from 30 to 70 or
sometimes higher percentage. Examples are Indra Canal in
Rajasthan.
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Cover materials constitute cement/concrete. Due to expansion-contraction &
when we wet at the bottom the base, then limited supply at the base. The
cover materials usually cracks in 3-4 years and thus losses its purpose.
200 LDPE sheet used is damaged in the construction and serves little no
Purpose for seepage control.
Impervious sheet materials are highly extensible and thus on application
of tension these extend whereas the c/c system will fail due to cracking.
Approximate sheet materials like HDPE have very high puncture resistance
and thus are not affected due to construction over it. Other advantages of
the sheets are
(a)A long life 30 years
(b)Need little maintenance
(c)Seepage reduced from 30% to 50% or better
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Advantages of these sheet materials
1. Thickness in the range of 0.6 mm and thus lower mass of the material.
2. Lower thickness, more flexible and thus takes up the contour of the ground rather
easily
3. The material could be field sealed and thus required minimum field sealing.
4. Field sealing is relatively easy.
5. It does not stress crack.
6. Easy transportation.
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Demonstration: (Support from Ministry of Water Resources as a funding to IITD)
IIT Delhi – Dr. Nilesh Revagade, Dr. B. L. deopura, Dr. B. R. Charar
IARI- Dr. A.K. Singh & Dr. Manoj Khanna
Bhuvaneshwar – Dr. R.C. Srivastava
Port Blair – Dr. R.C. / Dr. S.K. Ambast
Karjet, Maharastra – Mr. Paranjpe
Demonstration at IIT Delhi –
Initiated in Oct/Nov. 2005 (Over 3 years)
Last three years – Seepage of 10-4 m /day (?)
The material character evalued are identical to the original material
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Application areas of the sheet material
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Ponds
Canals
Front face of the barrier for reservoir
Repair of the existing ponds, canals, tanks
and reservoir barrier are plentiful.
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Critical Parameters for the sheet materials in puncture resistance
HDPE sheets used internationally have the following limitations:
1. Thickness in the range of 1.5 to 2.0 mm and thus are very rigid.
2. Difficulty in transportation and installation on site due to rigidity.
3. Widths are limited to 5-8 m and thus there is failing large field sealing.
4. Field sealing is a specialized job.
5. Minimum weight of a single unit is in around 5 tones and require automation
for installation.
6. HDPE is
to stress-crack and thus ground preparation must be very rigid
, very smooth.
6. PVC sheet materials were used for this purpose. It is known to leach out the
plasticizer in water and contaminate it. There are issues with UV stability of
PVC.
We have developed a range of these sheet materials with thickness ranges from
0.6 mm & puncture resistance equivalent of ~ 1.5 to 2.0 mm HDPE.
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Field Trials 1
Water Technology Centre (WTC) Indian
Agriculture Research Institute Delhi
A channel of length 120 x 4(P)m
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