Exploitation of Groundwater. Describe about methods of drilling deep wells, well design criteria, Pumping and protection of Wells.

1. Exploitation of Groundwater
Presented By:
Saroj Shrestha (9)
Saurav Poudel (11)
Samyog Khanal (13)
Sapna Badekar (15)

2. Introduction
Groundwater exploitation refers to the
drilling and pumping of groundwater by
people in order to use this groundwater
for various purposes
The proper exploitation of ground water
resources involves apart from the location
of suitable source, the construction of
properly designed wells
Numerous problems of ground water
exploration & exploitation require
systematic use of scientific techniques

3. GROUND WATER ABSTRACTING STRUCTURES
 The ground water abstracting structures are man made which collect & hold
water for exploitation.
 The common ground water abstracting structures are Dug wells, Dug cum
bore well, bore well, collector well & Infiltration gallery.
 Wells are vertical shafts excavated or holes drilled in earth to the level of
water table for extraction.
 The wells have to be designed to get the optimum quantity of water
economically from a given geological formation

4. Groundwater Wells
 a hole or shaft
 Usually vertical, excavated for bringing groundwater to the surface
 Success of ground water exploration program depends on the exploitation of
it
 The ground water explored should be extracted by abstracting structures like
dug wells & bore wells adapting proper exploitation techniques

5. Types of water well
Dug well
Bored well
Driven wells
Jetted wells

6. Methods of Drilling Deep Wells

7. Cable Tool Method
An impact tool or bit, suspended in the well from a steel cable, is
dropped repeatedly on the bottom of the hole to crush the rock
Capable to drill holes upto 8 to 60cm through consolidated rock
material.
least affective in unconsolidated sand and gravel.

9. Rotary Method
 Uses a sharp, rotating drill bit
and downward pressure to cut,
or crush, through the
subsurface
 Capable to drill holes 45cm
through unconsolidated strata
 Rapid method

10. Air Rotary Method
 Use compress air
 Rapid and convenient for small diameter hole drilling in
unconsolidated strata
 Drilling Depth can exceed 150 meter under favorable circumstances
 Advantage
 Ability to drill through fissured rock formations with little or no water
required

11. Rotary Percussion Method

12. Reverse Circulation Rotary Method
 Method of drilling which uses dual
wall drill rods that consist of an
outer drill rod with an inner tube
 Use to drill large diameter hole in
unconsolidated strata.
 Drilled fluid is clear water

13. Well Design
 The success of well depends on well design and construction. The tube well
design shall ensure an efficient and economical well with a service life of
more than one decade
 The size of the well should be properly chosen since it significantly affects
the cost of well construction.
 Well must be large enough to accommodate the pump to be installed.
 Before installation of screen it is essential to check the verticality of
borehole.
 borehole. The optimum length of well screen is chosen in relation to the
aquifer thickness, available drawdown and stratification of aquifer.

14. Well Design Criteria
 The choice of open well or bore well & the method of well design
depends upon topography, geological conditions of the underlying strata,
depth to water table, rainfall, climate and the quantity of water required
 A water well design involves selection of proper dimensions like the
diameter of the well & casing, length & location of the screen including
slot size, shape & percentage open area.

15. Well Screen
Provision of a suitable
well screen is the most
important part of well
design
The selection of screen
size includes, type of
screen, the entrance
velocity, the open area
& diameter & length of
the screen

16. Well Completion
 The process of making a well ready for production after drilling operations
This involve
 Placement of casing
 Cementing of casing
 Placement of well screen
 Gravel packing

17. Well Casing and Cementing
 A lining installed in well to maintain
an open hole from ground surface.
 It seals out surface water, undesirable
groundwater and provide structural
support.
 Cementing is done to prevent
entering the unsatisfactory water, to
prevent from corrosion and stabilize
the caving rock formation.

18. Placement of Well Screen and Gravel Packing
Screen allow to enter maximum
amount of water
Gravel packing is artificially placed
graver to surround the screen.
 To prevent sand pumping
 Stabilize aquifer

19. Well Construction
 The suitability of well construction depends upon the geology, depth to
water level and design of tube well
 Placement of gavel or pebble packing around a well has to be done carefully
to avoid segregation or bridging.
 The gravel pack materials should be clean, rounded, smooth and uniform.
The maximum grain size should be less than 10 mm.

20. Pumping
 Pumping test is done to determine:
• Performance characteristics of a well
– Yield and drawdown are recorded so that specific capacity can be
calculated. Also gives info on pump capacity required.
• Hydraulic parameters of the aquifer or aquifer test
– Transmissivity and storage coefficient can be calculated
 Pumping test will not give accurate results if not done methodically
 pumping should be done for several hours to determine:
– Max. anticipated drawdown
– Vol of water produced
– Best method to measure yield
– Means to avoid instant recharge

21. Pumping Equipment
•Well Pumps produce flow by transforming mechanical energy to
Hydraulic Energy.
•The selection of size and type of pump depend on
a) Pumping Capacity
b) Well diameter and Depth
c) Depth and Variability of Pumping Level
d) Straightness of the Well
e) Sand Pumping
f) Total Pumping Head
g) Duration of Pumping
h) Type of Power Available

22. Total Pumping Head/ Total dynamic Head
It represents the total vertical lift of the water from the well.
It consist of three components
a) The drawdown inside the well ( Including aquifer and well
Losses)
b) The Static head
c) Friction loss due to flow.
 Total Pumping head increases with Discharge.

23. Figure:- Diagram illustrating total pumping head for a well supplying a storage
reservoir.

24. Pumps For Shallow Wells
Only small Discharge is needed.
Discharge range up to 500m3/day.
Hand-operated pitcher pump, turbine pump, and gear
pump are installed.
For large discharge from shallow well centrifugal pump
are used.

25. Pumps for Deep Wells
Large-capacity pumps serving irrigation, municipal,
or industrial water requirements.
Plunger, displacement, airlift, jet deep well turbine
and Submersible pump are example.
The deep well turbine pump has been widely adopted
for large, deep, high-capacity wells.
The pump is usually driven by an electric motor at the
ground surface.
An advantage of submersible pumps is that they can
lift water from deep wells.

26. Figure:- Pumps for deep wells. a) Turbine b) Submersible (After Anderson
1966)

27. Photograph:- Photograph showing the process of Pump installation. (PCLRIP,
2021)
Some Features of Pump:-
Brand:- KSB Make
Phase:- 3 Phase
Pump Power:- 20HP
Stage:- 10 Stage
Type of Pump:- Submersible
water Pump
Set Model :- BPD 242/ 10A+
UMAI 1509122”

28. Photograph:- Photograph shows the final Discharge of pump.

29. Protection of Wells
a) Sanitary Protection
b) Frost Protection
c) Abandonment of Wells

30. Figure:- Plan and Elevation views of a developed spring showing a typical method for
providing Sanitary Protection (After Us Public Health Service)

31. Figure:- A drilled well showing grout seal, concrete slab, and well seal for
sanitary protection (After Us Public Service)

32. Figure:- Diagram of a domestic well Installation with a pitless adapter to protect the well
from frost (After Gibb)

33. Conclusion
Dug wells, Bored wells, Driven wells and Jetted wells
are used for the constructing shallow wells.
Cable toll method, Rotary Method, Air rotary method,
Down the Hole and Reverse circulation rotary
method used for drilling deep wells.
Well Casings, cementing, screens and Gravel packing
is done for Well Completion.
Pumping, Surging, Backwashing with air and
Hydraulic jetting are done for well Development.
Submersible pumps are used for pumping in deep
wells.
Sanitary, frost protection are usually done for the
Protection of wells.

34. Thank you!
Any Questions?