TM 5-815-5/AFM 88-5, Chap 6/NAVFAC P-418
from the well filter and the natural pervious informa-
with the manufacturer's recommendations prior to
tion after the well is installed.
surging.) Development of the well shall be started
within 4 to 12 hours after the well has been installed.
(d) Installation of well screen and riser.
Step 1. Assembly. The joints between the
Surging of the well shall be accomplished with a surge
screen sections and between the screen and riser pipe
block raised and lowered through the well screen at a
shall be welded with stainless steel rod. Particular care
speed of 2 to 3 feet per second. The gaskets on the
should be exercised to avoid damaging the screen and
surge block shall be slightly flexible and have a diame-
riser. It shall be centered in the well hole or casing and
ter about 1 inch smaller than the inside diameter of
held securely in place during placement of the filter by
the well screen. The amount of material deposited in
means of spiders and approved centering guide, tremie
the bottom of the well shall be determined after each
holder, or other approved method. Prior to installation
cycle (about 10 to 20 trips per cycle). Surging shall con-
of any screen and riser the Contractor shall submit to
tinue until the accumulation of material pulled
the Contracting Officer for approval full details of the
through the well screen in any one cycle becomes less
method, equipment, and devices he proposes to use for
than 0.2 foot. The well screen shall be bailed clean
with a piston-type bailer when the accumulation of
centering and holding the screen and riser pipe in the
well hole.
material in the bottom of the screen becomes more
Step 2. Installation. The assembled screen and
than 2 to 3 feet at any time during surging; the well
riser pipe shall be placed in the well hole in such a
shall also be cleaned after surging is completed. After
manner as to avoid jarring impacts and to insure that
completion of surging, the well shall be pumped with
the assembly is not damaged or misaligned.
the pump section about 1 foot off the bottom of the
well until the discharge is clear and is reasonably free
Step 3. Alignment. Each completed well shall
be sufficiently straight and plumb that a cylinder 10
of sand (less than 10 to 20 parts per million sand).
feet in length and 2 inches smaller in diameter than
Such pumping shall begin within 2 hours after surging
the inside diameter of the well may be lowered for the
and shall continue for not less than 30 minutes. The
well shall be pumped so as to achieve a drawdown of
full depth of the well and withdrawn without binding
against the sides of the screen or riser pipe. A varia-
not less than 20 feet, or a flow of approximately 1000
tion of 6 to 12 inches will be permitted in the align-
gallons per minute, whichever is first. If, at the com-
ment of the screen and riser pipe from a plumb line at
pletion of pumping, the well is producing sand at a
the top of the well; however, this will not relieve the
rate in excess of 10 to 20 parts per million, it shall be
Contractor of the responsibility of maintaining ade-
resurged and pumped again. Alternate surging and
quate clearance for bailing, surging, and pumping re-
pumping shall be continued until material entering the
well during either surging or pumping is less than the
quired for pumping the wells.
(e) Placement of sand filter (A). After the screen
amount specified above, but not for a period longer
and riser pipe have been placed, the filter sand shall be
than 6 hours. Wells which continue to produce an ex-
tremied into the annular space between the well screen
cessive amount of sand or filter material during devel-
or riser pipe and the drilled hole using a 4- or 5-inch-di-
opment shall be abandoned as requested by the C.O.R.
ameter tremie pipe with flush screw joints and at least
except that, if he or she so elects, he or she may re-
two slots 1/16 inch wide and about 6 inches long per lin-
quest the Contractor to continue to develop the well by
ear foot of tremie. The tremie pipe shall be lowered to
an approved method. If, after such further develop-
the bottom of the hole and then filled with filter sand.
ment, a well meets the above stated requirements, it
(If the filter sand has a tendency to segregate, the fil-
shall be completed, and after successful completion of
ter sand shall be kept moist following delivery to the
the required pumping test, the well will be accepted.
work site in order to minimize segregation.) After the
If, after completion of all surging and pumping, there
tremie has been filled with filter sand, it shall be slow-
is more than 0.5 foot of material in the bottom of the
ly raised, keeping the tremie full of filter sand at all
well, such material shall be carefully removed with
times until the filter sand has filled the hole up to
either a piston-type bailer or by pumping. The water
within 15 feet of the ground surface. The bottom of
resulting from pumping the well shall be discharged
the tremie pipe shall be kept slightly below the surface
outside the work area at locations approved by the
of the filter sand in the hole as the tremie is raised.
C.O.R. Pertinent data regarding installation of the
(f) Development of well. After installation of
wells will be recorded by the C.O.R. After completion
the well, it shall be developed by surging with a surge
of satisfactory development of a well, the grout seal
block and pumping, as described below, for not less
shall be placed.
than 30 minutes. (If Revert or equivalent approved or-
(g) Disinfection of drill hole and filter sand.
ganic drilling additive has been used in drilling the
During the drilling operation, a minimum of 1 pound
hole, a breakdown agent such as Johnson's Fast-Break
of calcium hypochlorite shall be added to the drilling
or equivalent shall be added to the well in accordance
fluid every 2 hours. As the filter sand is placed in the
G-13
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