than the inside diameter of the well. Should the cylinder fail to move
freely throughout the length of the well, the alignment of the well shall
be corrected by the Contractor at no additional expense to the Government.
3.3
FILTER PACK PLACEMENT
After the well screen and riser pipe have been installed, the filter pack
material shall be placed by tremie, when using a well graded material, in
an approved manner such that segregation will not occur. When using a
uniform graded filter material, the material may be poured around the well
screen at a rate that will prevent bridging of the material. The material
should be placed around all sides of the screen to assure that the screen
is not pushed against the side of the bore hole causing the screen to come
in contact with foundation material or prevent the proper thickness of
filter from being placed uniformly around the screen. The filter pack
shall have a minimum thickness of [_____] mm inches between the outside of
the well screen and the natural formation. The filter pack shall be placed
at a constant rate from the start of placement until it has reached the
elevation [shown], [directed] [a minimum of 600 mm 2 feet above the top of
the well screen]. If a tremie is required, a double string of tremie pipe
shall be used. The pipes shall be placed on opposite sides of the screen
and/or casing, that is, 180 degrees apart, and shall be guided in such a
manner that they will remain in this position throughout the placing
process. The tremie pipes shall be set in place, filled completely with
filter pack prior to being lifted off the bottom of the hole. The filter
pack in the tremie pipe shall be kept a minimum of 300 mm 1 foot above the
water surface in the well throughout the placing process. In no case shall
the gradation of the filter pack fall outside of the range specified in
paragraph FILTER PACK.
3.4
DEVELOPMENT
3.4.1
General
Following placement of filter pack materials, the Contractor shall develop
the relief well by jetting, surging, intermittent pumping, or other
approved methods as may be necessary to give the maximum yield of water per
300 mm foot of drawdown. At the time of development of any relief well,
the well shall be free of drawdown or surcharge effects due to pump
testing, developing or drilling at another location. The Contractor shall
be responsible for maintaining at the relief well the needed access and
work area and clearance in the relief well necessary to accomplish
development. The Contractor shall furnish, install, or construct the
necessary discharge line and troughs to conduct and dispose of the
discharge a sufficient distance from the work areas to prevent damage.
Development shall be conducted to achieve a stable well of maximum
efficiency and shall be continued until a satisfactory sand test, as
specified in paragraph SAND TEST, is obtained. As development proceeds,
filter pack material shall be added to the annular space around the screen
to maintain the top elevation of the filter pack to the specified
elevation. The Contractor shall provide an open tube or other approved
means for accurately determining the water level in the well under all
conditions. If, at any time during the development process it becomes
apparent in the opinion of the Contracting Officer that the well may be
damaged, development operations shall be immediately terminated. The
Contracting Officer may require a change in method if the method selected
does not accomplish the desired results. The Contracting Officer may order
that wells which continue to produce excessive amounts of fines after
development for 6 hours be abandoned, plugged, and backfilled, and may
SECTION 02525A
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