MIL-HDBK-1005/7A
is to be used as a measure of well capability for determining
the pumping lifts required at different pumping rates (expressed
as gallons per minute per foot (gpm/ft) of drawdown).
f) Spacing of Wells in the Field. Use test pumping
data to determine minimum well spacing. Use the data collected
from the pumping test to evaluate the effects of interference
between wells. The drawdown at any point in the area of
influence, caused by the discharge of several wells, equals the
sum of the drawdowns (at that point), caused by the wells
individually (unless the formation has severe limiting
boundaries). Determine the final spacing of wells from
investigation of the following factors:
(1) Operation estimated to be successful during
the life of the facility.
(2) Extra pumping life required for closely spaced
wells and increased pumping costs.
(3) Extra piping and power transmission lines
required for widely spaced wells and resulting costs.
4.4.1.3
Well Construction . Refer to Groundwater and Wells by
Driscoll for detailed construction methods.
4.4.1.4
Well Development. After completion, each well should
be developed to full capacity. The most commonly used methods
are pumping and surging; with surging being the preferred method
if sand is present or well capacity is low.
a)
Methods Available
(1) Pump Surging. This method involves repeated
cyclical pumping from a lower to a higher rate, until the
capacity of the well is reached.
(2) Surge Block. In this method, surging is
created by the rapid up-and-down motion of a plunger.
Hexametaphosphates may be added to the well water to free clays
or other fines. Surging should be continued until all sand and
mud are removed from the well.
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