How to Calculate the Volume of a Well
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.
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.
- The volume of the well is
- V = ((3.1416* 32)/4) *45
- V = 318.53 ft3
- 1 yd cubed = 27 ft3
- V = 11.79 yd3/li>
- The volume of the well is calculated by the formula.
- V = ((n * D2)/4)* d
- Where:
n = 3.1416 D = diameter of well (feet) d = depth of well (feet) - An abandoned well is 6 inches in diameter, 100 feet in depth, and the water level is 40 feet.
- 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
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