3.2
INSTALLATION OF RISER PIPE AND SCREEN
3.2.1
Assembly
All riser pipe and screen shall be in good condition before installation
and all couplings and other accessory parts shall be securely fastened in
place. The successive lengths of pipe shall be arranged to provide
accurate placement of the screen sections in the bore hole. [The
riser-pipe shall be provided with an approved cap and a flanged top
section, the top of which shall be set at the elevation directed or shown.]
Centralizers shall be attached to the assembled riser pipe and screen in
such numbers and of a type that they will satisfactorily center the riser
pipe and screen in the well and will hold it securely in position while the
filter pack material is being placed.
3.2.2
Joints
Sections of relief well pipe shall be joined together as specified in
paragraph COUPLINGS. Joints shall be designed and constructed to have the
strength of the pipe and where possible a strength capable to support the
weight of the relief well stem as it is lowered into the hole. When not
practicable to construct joints that will support the weight of the relief
well stem, the stem shall be supported at the lower end by any approved
means that will assure that the joints do not open while being lowered into
place in the well.
3.2.3
Installation
The assembled riser pipe and screen shall be placed in the bore hole in
such manner as to avoid jarring impacts and to insure that the assembly is
centered and not damaged or disconnected. The screen should be suspended
in the hole and not resting on the bottom of the hole. After the screen
and riser pipe have been placed, a filter pack shall be constructed around
the screen section as specified in paragraph FILTER PACK PLACEMENT and the
well developed as specified in paragraph DEVELOPMENT. The top of the riser
pipe shall be held at the designated elevation during placement of the
filter pack.
3.2.4
Check for Plumbness and Alignment
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NOTES: Alignment and plumbness tests are performed
to determine if a pump will be able to be installed
into the well at the end of development so that a
pump test can be performed. The variation of the
plumbness should not vary more than two-thirds of
the inside diameter of the well in 30 m (100 feet).
Select appropriate alternate paragraph.
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[Each well shall be sufficiently straight and plumb, such that a cylinder
[3][6][10][15] m [10][20][40] feet in length and with an outside diameter
13 mm 1/2 inch smaller than the inside diameter of the well may be lowered
for the full depth of the well and withdrawn without binding against the
sides of the well. The Contractor shall furnish the dummy cylinder and
perform the alignment check and plumbness check in the presence of the
Contracting Officer. A variation of [150][_____] mm [6][_____] inches per
30 m 100 feet of depth will be permitted in the plumbness of well from a
SECTION 02525A
Page 18
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