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= D=diameter of well (feet) d= depth of well (feet)

Hand Dug Well Example The volume of the well is V= ((3.416* 3 2 )/4) *45 V= ft 3 1 yd 3 = 27 ft 3 V= yd 3

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* )/4) *100 V= ft 3

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

Well or Hole Diameter CementBentonite Chips InchesLinear Feet

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.