*TM 5-813-1/AFM-88-10, Vol. 1
of not over 6 gallons per 94-pound sack of cement.
contamination and damage during flood periods and to
Small amounts of bentonite clay may be used to improve
facilitate operation during a flood.
fluidity and reduce shrinkage. Grout can be placed by
(2)
Surface slab. The well casing should
various methods, but to ensure a satisfactory seal, it is
be surrounded at the surface by a concrete slab having a
essential that grouting be:
minimum thickness of 4 inches and extending outward
-done as one continuous operation
from the casing a minimum of 2 feet in all directions.
-completely placed before the initial set occurs
The slab should be finished a little above ground level
-introduced at the bottom of the space to be
and slope slightly to provide drainage away from the
grouted
casing in all directions.
Establishment of good circulation of water through the
(3)
Casing.
The well casing should
annular space to be grouted is a highly desirable initial
extend at least 12 inches above the level of the concrete
step toward a good grouting job. This assures that the
surface slab in order to provide ample space for a tight
space is open and provides for the removal of foreign
surface seal at the top of the casing. The type of seal to
material.
be employed depends on the pumping equipment
(2)
Prevention
of
subsurface
specified.
contamination. Formations containing water of poor
(4)
Well house. While not universally
quality and located above or below the desired water
required, it is usually advisable to construct a permanent
formation must be sealed to prevent upward or
well house, the floor of which can be an enlarged version
downward migration of inferior quality water into the well.
of the surface slab. The floor of the well house should
Sealing of formations above or below the aquifer to be
slope away from the casing toward a floor drain at the
utilized can be accomplished by grouting the annular
rate of about 1/8 inch per foot. Floor drains should
space between drill hole and casing for the entire length
discharge through carefully jointed 4 inch or larger pipe
of the casing or by grouting this annular space only
of durable water-tight material to the ground surface 20
through formations containing water of poor quality. If
feet or more from the well. The end of the drain should
only the formations containing poor quality water are to
be fitted with a coarse screen. Well house floor drains
be grouted, the sections of the annular space not filled
ordinarily should not be connected to storm or sanitary
with grout must be filled with sand to prevent caving of
sewers to prevent contamination from backup. The well
the surrounding strata and to support the grout before
house should have a large entry door that opens outward
the grout has set. To provide a satisfactory seal, the
and extends to the floor. The door should be equipped
grout may need to extend 10 to 25 feet above and below
with a good quality lock. The well house design should
the formation producing the mineralized water and
be such that the well pump, motor, and drop-pipe can be
should be 2 to 6 inches thick in all locations.
removed readily. The well house protects valves and
g.
Accessibility. The well location shall be
pumping equipment and also provides some freeze
readily accessible for pump repair, cleaning, disinfection,
protection for the pump discharge piping beyond the
testing and inspection. The top of the well shall never be
check valve. Where freezing is a problem, the well
below surface grade. At least two feet of clearance
house should be insulated and a heating unit installed.
beyond any building projection shall be provided.
The well house should be of fire- proof construction. The
h.
Details relating to water quality. In addition
well house also protects other essential items. These
include:
to grouting and sealing, features that are related to water
-Flow Meter
quality protection are:
-Depth Gage
(1)
Surface grading. The well or wells
-Pressure Gage
should be located on the highest ground practicable,
-Screened Casing Vent
certainly on ground higher than nearby potential sources
-Sampling Tap
of surface pollution. The surface near the site should be
-Water Treatment Equipment (if required)
built up, by fill if necessary, so that surface drainage will
-Well Operating Records
be away from the well in all directions. Where flooding is
If climatic or other conditions are such that a well house
a problem, special design will be necessary to insure
is not necessary, then the well should be protected
protection of wells and pumping equipment from
5-15
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