Unconventional measurers sde11

1
Directorate of
Groundwater Surveys and Development Agency,
Pune
Unconventional Measures for Source Strengthing

GEOLOGY OF MAHARASHTRA
2
Deccan Trap 82 %
Specific yield 2 to 4 %

GEOLOGY OF MAHARASHTRA
• 82 % Deccan trap formation.
• Specific Yield not more than 2 to 4 %.
• Groundwater is available due to Secondary porosity.
• Drinking water sources particularly PWS Wells do not
have adequate yield during summer.
• Drinking water sources are dependant mainly on Rainfall
in case of less Rainfall sources gives inadequate yield or
get’s dried in summer .
• Hence these sources are need tobe strengthen by
different measures which are conventional &
Unconventional .
3

Conventional Measurers
 Deepening of Wells .
 Augmentation of existing Schemes by Horizontal &
Vertical bores In wells .
 Construction of new Bore well & Dug well .
 Check dams , Percolation tanks, Earthen nala bunds
, under ground bandharas etc.
 Augmentation of existing P.W.S
4

Following unconventional techniques have been
developed for the strengthening of drinking water
sources.
1. Bore-blast-technique.
2. Jacket well -technique
3. Stream blast- technique.
4. Fracture Seal Cementation
5. Hydrofracturing to bore wells .
6. Artificial recharge of bore well & dug well by
flooding , Rainwater harvesting , Rechage shaft
etc.
Implemented as per location and Characteristics
of the aquifers. 5

GSDA’s SOLUTION SINCE 1983
Unconventional Measurers for
Drinking Water Source
Strengthening.
6

Unconventional Measurers for
Drinking Water Source Strengthening.
• Most suitable Techniques to improve the
storativity and transmissivity of the aquifers in
hard rock terrain.
• GSDA developed and implemented first such
scheme during 1983 in the Saraste Village of
Nashik District.
• Since then 2492 such projects have been
implemented by GSDA.
7

METHODOLOGY & DESIGN OF
UNCOVENTIONAL METHODS

1.Jacket Well Technique (JW)
• Jacketing of well with the
blasted bore holes
increases effective
diameter of the well
thereby improves the
storativity and
transmissivity of the
aquifer. 9

Boreholes are drilled around the targeted
well to a depth little less than the depth of
well.
• Subsequently blasting is carried out to create
artificial fractures in the compact rocks.
• These bores are drilled either in circular, semi
circular or any other desired pattern depending
upon the prevalent topographical and hydro
geological conditions.
• Explosives of required strength and quantity are
used to create maximum fractures and to inter-
connect them.
11

12
• Sand is generally staved in the boreholes for effecti
Jacket well

2.Bore Blast Technique (BBT) :-
• Bore blast technique is adopted to create
more storage space for groundwater in
massive and crystalline hard rocks by
fracturing.
14

15
Boreholes for
blasting
Source
well
Underground
bandhara
Highly weathered
zone soil
Top
view
Moderately
weathered
zone
Highly weathered
zone
Source
well
Ground
level

• Hydrogelogical
and Geophysical survey has to be carried out to know r
• Bores are drilled in staggered pattern.
• suitable explosives to be lowered in 2 to 3 sections for e
16

Bore Blast Technique
17
Bore Blast Technique

Bore Blast
Technique
18
OK: SIGNAL (Red Flag) Before Blasting
Bore hole Blasting

• This technique is applied in areas where
landforms are mostly hilly.
• Being a high cost measure this technique
should be adopted to provide drinking water,
when no other measure is feasible/possible.
19
BBT

3.Stream Blast Technique ( SBT):-
• Generally, drinking water wells are situated on nalla
banks.
• At some places, the groundwater flowing below the
nala bed has no hydraulic connectivity with the well,
and the well becomes dry or partially dry during
summer months.
• Such well can be rejuvenated by this technique,
known as stream blasting.
• In this technique, the area of nalla bed within the
vicinity of well is investigated geophysically and
geohydrologically. 20

• Then bores are drilled in the nala bed to a
depth of open dug well.
• These bores are in staggering pattern to get
maximum blasting effect in minimum
number of bores.
• Pattern and number of bores is decided
considering the hardness of the strata to be
fractured or shattered.
• These boreholes are further charged with
explosives and blasted to create fractures
and joints artificially. 22

• These artificially created fractures get
connected to the well and divert
groundwater from nalla to the well.
23
SBT

Design Calculations.
• Calculate the volume of rock of each bore-hole to
be fractured by blasting.
• For example if,
• Hard rock depth (h)= 7 meters,
• Spacing between the bores = 4 meters
• Radius = 2 mtrs.
• Therefore volume of rock = ¶r2
x h
• = 22/7 x22
x 7 = 88 m3 .
• Quantity of explosives required is 150 gms.
per m3. ( 0.150 Kg)
• Therefore for 88 m3 rock quantity of explosive
required = 88 x 0.150
• = 13.20 kgs.
24

Continued
• The diameter of the bore-hole is 100-115 mm.
• Use 83 mm dia. slurry explosives (Class 2), the
weight of each bag being 2.78 kgs.
25

Continued
• Weathered Zone should not be charged.
• 1.5 to 2.0 meters below the depth of
weathered zone, explosive charge of 2.78 kgs.
= 1 bag should be provided.
• Distance between two explosive charged i.e.
section interval may be taken as 2-3 meters.
• Bottom charge should be more.
26

27
0 GL
10 m
Explosives charge
2.78 Kgs
Explosives charge
5.56 Kgs
Explosives charge
5.56 Kgs
Sand Stemming
Weathered
Zone
2 m
5 m

Design and Methodology of unconventional Blasting
technology.
 Bore-hole drilling pattern is decided as
per site condition and, this pattern may
vary from site to site depending upon the
geological conditions.
 Bore-holes of suitable diameter (100-150
mm) are drilled to the required depth or
to a depth of shallow aquifer.
28

• Generally 10-15 meters deep drilling of
holes would be adequate.
• Distance between the bore-holes i.e.
spacing is decided as per site conditions
and based on past experience.
• Generally spacing is kept 3-5 meters in
basaltic hard massive rock.
29

Continued
• Staggering pattern of bore-holes is
preferred.
• Suitable type of explosives and
explosives charge should be lowered into
bore-holes to be blasted.
• At any time, not more than 5-6 bore-
holes should be charged and fired
(blasted).
30

Continued
 Charging and blasting operations should
be started from the bore-hole which is
lying at the centre of the site and then
extended Radially in all directions till the
operations are complete.
 Controlled blasting of the bore-holes is
preferred and if this is not possible or not
practicable then, instantaneous blasting
may be carried out.
31

Continued
• Blasting in hard rock only should be
carried out i.e. weathered zone should
not be charged and blasted.
32

Fracture Seal Cementation
• Groundwater migration through a network of
shallow depth aquifer from the discharging location
is arrested by this technique.
• Cementation may be defined as injection of cement
slurry under pressure to fill voids, cracks seams,
fissures or other cavities.
• The result is to ensure water tightness by
establishment of very low permeability.
33
Fracture FSC-1 FSC-2

Hydrofracturing.
Hydrofracturing
is a Greek word.
Hydro means water.
Hence Hydrofracturing means
Fracturing with the help of
water.
34

Hydrofracturing is a process in which
pressurized water is injected into the
bore well to increase the permeability of
the consolidated material or a relatively
impermeable unconsolidated material.
Which improves the yield of the bore
well.
 Success ratio is about 65 %.
35

Successful borewell ?
• Successful borewell
should provide
hygienic, safe, potable
drinking water to 250
souls through out the
year , 40 liters per day
• maintaining swl less
than 36 m.for easier
operation of the pump.
< 36 mtrs
B/w

Poor yielding Bore wells
1.The b/w is
isolated from the
nearby water
bearing zone by a
massive rock
intervening
between the b/w
and water
bearing zone.
massive rock
water bearing zone
B/w

2.The aquifer contains
closed fractures or
the b/w is poorly
connected to a
nearby water
bearing zone due to
the low permeability
of the intervening
rock between them
water bearing zone
B/w
aquifer contains closed fractures

3.The bore well yield
low because some of
the open fractures
are
choked with
accumulates such as
clay,resulting in
large reduction of
hydraulic
conductivity of
aquifer-fracture
system.
Choked aquifer.
water bearing zone
B/w

• All these bore wells falling under
above three categories can be
considered for the treatment of
hydrofracturing techniques to
improve the yield.
Because

Because
Hydrofracturing is a process in which pressurized
water is injected into the borewell to increase
the permeability of the consolidated material or
a relatively impermeable unconsolidated
material.Which improves the yield of the bore
wells.

Methods of improving efficiency of
the bore wells.
1.Augmentation of bore wells.
2.Improvement of storage capacity of
the aquifer.

Methods of improving efficiency of the
bore wells. ( Continued.)
1.Augmentation of bore wells
by improvement in the yield.
a) Sectional blasting.
b) Hydrofracturing.
2. Improvement of storage capacity of
the aquifer by Accelerating
Groundwater movement and
recharge --use of HF

Methods of improving efficiency of the bore wells.( Continued.)
1. Augmentation of bore
wells by improvement in the
yield.
a) Sectional blasting.
Sectional blasting means
blasting of a bore well at
particular section to improve
the permeability of that zone.
Explosive
Exploder
Bore well

• Results of sectional blasting are more or
less futile,as blasting induced fractures
could penetrate to a distance of 2-3
meters only, which is not sufficient for
connecting a Bw to nearest water bearing
zone.
• It is not possible to control the
propogation of fractures because this is an
instant action.
Methods of improving efficiency of the bore wells.
( Continued.)

• Most of the bore wells taken for the drinking
water purpose are in the vicinity of villages
hence sectional blasting is having restricted
scope due to safety precautions.
Sectional Blasting . Continued.

Hydrofracturing.
HF is carried out by
sealing a section of
B/w & pumping water
at high discharge rate
into the sealed off
section.So that
enormous pressure is
created into the
confined space which
creates the fractures.
47

49
Due to creation of network of fractures
in the hard rock by Hydrofracturing:
• Yield of the BWs can be improved.
• Intake and storage capacity of aquifer
improves, which in turn improves
recharge.
• Hence the Bw become a sustainable
source

Hydrofracturing.
• To understand the principles of HF a
good example is of pumping air into
a balloon more than its capacity will
result into the bursting of balloon.
50

51
Water tanker.
HF Unit
Inflated Packer
rubber seals
Hydraulic
hand pump.
Pressure gauge
Hydraulic
packer
cylinder

52
Hydrofracturing Unit
Prime
mover
High Pressure
Water Injection Pump
Over head
Crane
Generator Set

54
Line Diagram
Water Tanker
Booster Pump
High Pressure water injection pump
(WOMA Pump)
Hydraulic Packer
HF Unit
High Pressure Hose.

57
Tee
Drain valve
Pressure Gauge.
Then release outlet
valve of
tee to drain water
under pressure in the
B/w.
When pressure of
drainage water falls
down
release packers and set
it to
next section and repeat
the process.

HF Observations
Fluid pressure in
the sealed
segment
instantaneously
increases till
breakdown
pressure(pc) is
reached.
58
Pressure
Time
Breakdown
pressure
(pc)

HF Observations
Then the fluid
pressure
suddenly drops
(pf)indicating
that a
hydrofracture is
initiated on the
b/w wall.
59
Pressure
Time
Breakdown
pressure
(pc)
(pf)

HF Observations
On further pumping of
the frac fluid the
fracture propogates.It
may be observed that
the pumping pressure
remains constant at pf
during propogation
hence it is called as the
fracture extension
pressure.
60
P
r
e
s
s
u
r
e
Time
Breakdown
pressure
(pc)
(pf)

HF Observations
When the pumping is
stopped and the B/w is
isolated from the
pump by shutting in
the valve in between
them then the fluid
pressure i.e. pf
instantaneously drops
to psi called as shut in
pressure.
61
P
r
e
s
s
u
r
e
Time
Breakdown
pressure
(pc)
(pf) psi

62
Time
P
r
e
s
s
u
r
e
Pc
pf
psi
Fluid pressure suddenly rises till the
breakdown pressure reached = pc
Then the fluid pressure
suddenly drops= pf
this is due to fracturing
of rock.
When the the
pumping is
stopped
then the pf drops
to psi i.e. shut in
pressure.

• During Hydrofracturing
average dynamic aperture
observed is 3 mm.
However on releasing of
pressure the fractures closes
back.
63
Post HF Results
But
the fractures do not
come back
exactly to their original
positions.

which act as a channel to transport
groundwater from the near by water
bearing zone into the B/w.
64
This
imperfect closure imparts
considerable
Improvement in the permeability
Post HF Results

65
This
results
in
Rejuvenating
the B/w.

• The well yield after HF is mostly
depends on the fracture created as
well as on the permeability of the
aquifer.
66
Post HF Results

HF Analytical Solutions.
We can Predict required frac fluid pressure, to
initiate a vertical hydrofracture .
Models provide theoretical basis to determine the
length and aperture of fracture as a function of :
Frac fluid discharge rate.
Pumping time.
Frac fluid viscosity.
Aquifer rock properties
Aquifer fluid properties.
67

• Also it predicts the distance to which
the pre existing fracture reopen.
• Requirement of max pumping
pressure,time of pumping,optimal
discharge rate have been worked out
for this.
68
HF Analytical Solutions .Contd

• Length and aperture of fracture
created is idealized as below:
• fracture length is directly
proportional to the discharge rate for
a given time of pumping.
• Q is constant in HF as 335 LPM
69

For the Propagation
up to
Pumping Time Required
in minutes.
100 m 20
200 m 40
300 m 60
70

• It can be decided the Q and time
required to get a particular frac
length.
71
HF Analytical Solutions .Contd

Conclusion
• For rejuvenating the low yielding borewells
HF is the most effective technique, provided
HF is carried out by pumping frac fluid at
fairly large discharge rate of 400-600 LPM.
• Success depends on the geohydrological
conditions of the aquifer.
• Efforts will be futile if there is no water
bearing zone near by.
72

Conclusion
• Every effort should be made to know the
success and failure of the HF.
73

These are few methods
GSDA is using for the
strengthening of Sources.
74

2.Accelerating
Groundwater movement
and recharge by HF

Accelerating Groundwater movement
and recharge by HF
• It is established that the HF can be
used to improve the recharge
conditions also.
• HF
• creates new fractures,
• cleans existing fractures,
• widen and propogates the fractures.

and recharge by HF
• In other way the above physical
changes in the properties lead to
improve the intake capacity
and storage capacity of the
B/w.

and recharge by HF
• It is observed that the intake capacity
of the B/w is improved by 3.5 times.
• It means the recharge can be
improved up to 3.5 times more by
HF .

Sr.
No.
Particulars Basalt
(bars)
Granite
(bars)
1 Break down pressure -Pc 110 145
2 Reopening pressure -Pr 70 75
3 Propogating pressure- Pf 60 40
4 Shut in pressure- Psi 40 70
5 Max.H.P.stresses -SH 50 75
6 Min.H.P.stresses -sh 40 50
7 Tangential stresses -T 40 70
777
Values determined for the basalt and granite.

Methodology.
• Measure intake capacity of the B/w.
• HF the B/w.
• Measure the post intake capacity.
• Select near by Surplus surface water
source.
• Install submersible pump on the B/w
(without foot valve.)
• Connect delivery pipe to surplus water
source.

Methodology.
• Observe that the submersible pump is
lowered below the level of intake
pipe line.
• Check the system is leak proof.
• Operate the sub.pump for few
minutes and stop the pump.

Methodology.
• Reversible flow will start from the
surplus water source to B/w.based on
siphon principle.
• Run the system round the clock till
the surplus water is available.
• Detach the pipe line after completion
of season.

Schematic diagram of
Reverse flow for recharge
Open well/Village tank/Percolation tank Siphon/Piping
B
o
r
e
w
e
l
l
G.L.
Submersible pump

Siphon in action
Dug well water is
recharged into the
Bore well.

Interpretations.
• It is observed that the recharge is
inversely proportional to the propogation
pressure.
• Hence while carrying out Hf it can be
predicted that if the propogation pressure
is less, the B/w is likely to accept more
recharge.
• Normally Dugwells can be taken as a
surplus water source for recharge.

DRINKING WATER SOURCE STRENGTHING AT VILLAGE HIVARE
BAZAR DISTRICT AHMEDNAGAR.
Design of Bore Blast (BBT)
•The area selected in the village
Hivare Bazar for blasting is about 5400 sq mt.
•The purpose of the
Project was to deviate
the shallow aquifer
water at the upper ridge
that was flowing outside
the watershed .

• The bore blasting was designed in such a way
that the water underground flowing outside
the village boundary was deviated towards
the village by creating artificial fractures in
the compact massive basalt which was
otherwise acting as a barrier for groundwater
recharge.

• Total 103 bore holes were taken with a depth
range of 5 to 18 Mts.
Vertical cross section

SR.
NO
LOCATIONS
13/7/07 14/7/07 20/7/07 31/8/07 15/10/07
(Before Project)
(After project)
Static water level below ground level in meter
1
Bore Well at up stream
side of project
3.9 3 4.4 4.4 1.2
2
Bore Well at down stream
side of project
14 14 0 0 0
3 Dug well Of Shri.Thange Dry Dry 15 2.55 2.1
Monitoring of Static water level of wells around the project site
Date of implementation of BBT project 20th July 2007.

SAROLA PATHAR, TALUKA SANGAMNER,
DISRTICT AHMEDNAGAR
• Village Sarola Pathar is among the ‘Hard Core
Villages’ where due to adverse hydro geological
condition, the inhabitants were deprived from the
basic need of potable drinking water. The
conventional measures like open dug wells and bore
wells could not fulfill the need
• Due to the geomorphologic conditions that are not
conducive to support the earlier measures and non-
implementation of regional pipe water scheme, the
tanker water supply was made since four years to
fulfill the village demand during summer.

UCM MEASURES PROPOSED
• The measures proposed were examined in the field
and suitable structures for arresting rain water flow,
Augmentation of existing borewell by hydro
fracturing, augmenting the ground water storage of
existing open well, cutoff wall by bore well with
fracture seal cementation, recharging the dyke at up
stream by rain water harvesting through village tank,
feeding the harvested water to dyke through
recharge trench and plugging out flow from the dyke
at down stream were proposed for implementation.

• In this village three measures have been completed
successfully. The dyke which was running from SE-NW was
found to be a carrier dykes in nature. This dyke was plugged
with the help of an unconventional measure, fracture seal
cementation. (F.S.C.) In this method number of borewells are
drilled on the downstream of the source well and cement
slurry is injected in the borewells with pressure. The plugging
of dyke has restricted the movement of subsurface flow.
• After the F.S.C. this dyke was fed with existing village
tank water by trenching, this made the availability of
groundwater to the existing source, thus the groundwater
source was rejuvenated.

• The last measure that was taken up was the hydro fracturing
of the existing bore wells. A new bore well drilled in March
1993 yielded 19191 lph of water. A power pump of suitable
horsepower was installed on this high yielding bore well and a
mini pipe water supply scheme was established on this
source. This indicates that there was an overall saturation of
groundwater in the project area with a definite increase in
the availability of groundwater after the project. As on today
there is adequate drinking water in the village.
• The impact of hydro fracturing was seen with a sudden
rise in the water level. The poor yielding bore well no. 3 has
become a sustainable source for drinking water.

Graph showing differences in the yield of bore well
after F.S.C. & Hydro fracturing
0
1000
2000
3000
4000
5000
6000
Borewell
1
Borewell
2
Borewell
3
Yield in LPH Prior
Yield in LPH After

Unconventional measurers sde11

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