How to Calculate the Volume
of a Well
Introduction
•
•
•
•
Discuss which dimensions are needed.
How to obtaining the dimensions.
Example
Alternative method
Goals of this Presentation
• Establish the importance of properly
calculating the volume of a well.
• Describe the dimensions that are needed
for the calculation and how to obtain them.
• Create a clear understanding of the
calculations through an example problem.
• Describe alternate methods to completing
the calculations.
Why is this important?
• The volume of the well is used to
determine the amount of plugging material
needed.
• The volume is also used to determine the
needed amount of disinfectant.
• Assuming the wrong volume of the well
could lead to many future problems.
According to the video what
dimensions are needed in order to
accurately calculate the volume of
a well?
• Well diameter
• Total depth
• Depth of the water
Obtaining Well Dimensions
• Diameter of the well – measured distance across
the inner lip of the well
• Total well depth – measured distance from top to
bottom of well.
• Water depth – measured distance of depth of
water in the well. (Tie a weight to some string
and drop it to the bottom of the well. Retrieve the
string and measure the portion of the string that
is wet.)
Hand Dug Well Example
• You have large hand dug well that is 3 feet
in diameter and is 45 feet deep. The
depth of water in the well is 10 feet.
Hand Dug Well Example
• The volume of the well is calculated by the
formula.
V = ((Π * D2)/ 4)* d
Where :
Π= 3.1416
D=diameter of well (feet)
d= depth of well (feet)
Hand Dug Well Example
• The volume of the well is
V= ((3.416* 32)/4) *45
V= 318.53 ft3
1 yd3 = 27 ft3
V= 11.79 yd3
Example
• An abandoned well is 6 inches in diameter,
100 feet in depth, and the water level is 40
feet.
Example
• The volume of the well is
D= 6in/ 12in/ft = 0.5 ft
V= ((3.416* 0.52)/4) *100
V= 19.62 ft3
Alternate Method
• Use Table 1 Plugging Material Calculation
Sheet.
• And the diameter of the well.
Well or Hole
Diameter
Cement
Bentonite Chips
Inches
Linear Feet
Linear Feet
2
50.3
31.3
3
28.8
13.9
4
16.2
1.9
5
10.4
5
6
7.2
3.5
7
5.3
2.6
8
4
2
9
3.2
1.5
10
2.6
1.3
12
1.8
0.86
14
1.3
0.63
16
1
0.48
18
0.8
0.38
20
0.6
0.31
24
0.4
0.21
36
0.2
0.097
40
0.16
0.078
44
0.13
0.065
48
0.11
0.054
Alternative Method
• Bags of cement needed (94 lb per sack)
100 feet / 7.2 feet = 13.8 sacks
• Bags of Bentonite needed (50 lb per sack)
100 feet / 3.5 feet = 28.5 sacks
Conclusion
• Well depth, diameter, and depth of the
water are all needed in calculating the
volume of the well.
• How to obtain these dimensions.
• There are several ways to calculate the
amount of plugging material that is
needed.