How to Calculate the Volume of a Well

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How to Calculate the Volume of a Well
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Introduction

• Discuss which dimensions are needed.
• How to obtaining the dimensions.
• Example
• Alternative method

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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.

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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.

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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

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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.)

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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.

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Hand Dug Well Example

• The volume of the well is calculated by the
  formula.
• V ((? D2)/ 4) d
• Where
• ? 3.1416
• Ddiameter of well (feet)
• d depth of well (feet)

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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

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Example

• An abandoned well is 6 inches in diameter, 100
  feet in depth, and the water level is 40 feet.

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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

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Alternate Method

• Use Table 1 Plugging Material Calculation Sheet.
• And the diameter of the well.

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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

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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.