MIL-HDBK-1164
APPENDIX A (Continued)
Static Level, Pumping Level, and Drawdown Calculation
1. Assume a length of air line (L) of 150 feet (ft). Assume that the pressure gage
reading (P1) before starting the pump is 25 pounds per square inch (psi).
2. Convert pressure to feet of water (A) to determine the height of water above the
bottom of the air line: (A) = 25 2.31 = 57.7 ft.
3. Calculate the static water level (B) by subtracting the calculated height from the
known air line length:
(B) = L - A = 150 - 57.7 = 92.3 ft.
4. Assume that the gage reading (P2) during pumping is 18 psi. Convert this pressure
to feet (C) to determine the height at which water stands in the well above the
bottom of the air line during pumping: (C) = 18 2.31 = 41.6 ft.
5. Calculate the pumping level (D) by subtracting (C) from the known length of air line:
(D) = L - C = 150 - 41.6 = 108.4 ft.
6. Determine the drawdown using any of the following methods:
D - B = 108.4 - 92.3 = 16.1 ft
A - C = 57.7 - 41.6 = 16.1 ft
P1 - P2 = 25 - 18 = 7 psi; 7 psi 2.31 = 16.1 ft
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