the water.
When the water clears, place the hose in the tank.
Perform
during-operation PMCS.
5. As a quick method to determine pumping capacity of the well, have your
soldiers assist you in the following well pumping test: Determine the time
it takes to fill a 5-gallon bucket.
Divide this time by 60 seconds.
Multiply that number by 5 to obtain the GPM pumped.
6. A more detailed description of well-testing and wellhead operations is
described below.
a. First determine the static level of the well. Before being pumped,
the level of water in a well is the same as the level of the water table.
This is called the static level in the well.
The depth from the ground
surface to the static water level is measured in feet.
b. Next determine the pumping level of the well.
When a well is
pumped, the water level drops. After several hours of pumping at a constant
rate, it stabilizes itself in a lower position. This is called the pumping
level or dynamic water level for this rate of pumping.
c. Now determine the drawdown of the well. The distance that the water
is lowered by pumping is called drawdown. It is the difference between the
static level and the pumping level.
The drawdown in the well, resulting
from the pumping, lowers the water pressure in the well, but the surrounding
water-bearing ground retains its original pressure.
In response to this
difference in pressure, water flows out of the pores of the ground into the
well.
d. Never draw down a well beyond 50 percent of its total depth. All
military wells use a 50-GPM submersible pump. With the same depth of water
in several different wells, less drawdown at the same pumping rate would
indicate larger capacity, or a smaller percent of drawdown.
e. Reduce well drawdown to an amount that provides sufficient
quantities to meet requirements. Determine the amount of water required to
be purified and distributed to soldiers from a well per day.
The pumping
rate should be regulated to produce that amount for as long a period of time
as possible, within the limitation of the pump and capacity of surface
storage.
f. In computing the percent of drawdown for a well, first determine the
depth of the well, the static water level of the well, and the pumping rate
(GPM and time). Determine the depth of water in the well by subtracting the
static water level from
QM4912
4-6
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