2.2.1
Metal Screen
Metal screen shall be of an approved wire-wound type and shall be [type
304] [or] [type 316] stainless steel, conforming to the applicable
requirements of AWWA A100. A wire-wound screen manufactured with
supporting bars or core of material different from the wire will not be
acceptable. Joints shall be made of threaded couplings of the same
material as the screens or by brazing or welding in accordance with AWWA
C206.
2.2.2
Plastic Screen
2.2.2.1
Plastic Pipe
Plastic pipe shall be thermoplastic manufactured by a molding, extrusion
or sonic welding process. The plastic compounds shall be uniform in
composition and shall not contain additives or foreign matter. The molding
or extrusion process shall produce pipe that is homogeneous throughout and
free from visible cracks, holes, foreign inclusions or other defects. Pipe
produced by simultaneous multiple extrusion shall have strong uniform bonds
between any two layers so that the layers cannot be separated. Plastic
pipe shall be uniform in color, opacity, density and other physical
properties.
Plastic pipe, and screen material shall conform to ASTM F 480.
All PVC plastic pipe shall conform to ASTM D 1785.
2.2.2.2
Bonding Materials
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NOTE: When sampling for trace level contaminants in
a well, the use of any solvents to join casing
should not be allowed.
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Bonding materials, proportions and preparation of adhesives, the method of
application, and the procedure used for making and curing the connections
shall conform to the recommendations of the plastic pipe manufacturer and
ASTM F 480. The pot life, initial setting time and external heating
requirements for curing of the adhesive shall be suitable for the procedure
and climatic and other conditions and shall be varied as required to suit
changes in climatic and other conditions. The system for making joints at
the well site shall provide a curing period adequate to develop the
ultimate strength of the completed joint. Self-tapping screws or other
devices for holding adhesive-coated pipe in the couplings during the
setting period [may] [shall not] be utilized. Newly-made joints in the
casing shall not be stressed, lowered into the well or submerged in water
prior to complete curing of the adhesive.
2.2.2.3
Plastic Well Screen
Plastic well screen shall be provided with perforations which shall consist
of either machine-sawed slots, continuous wrap or wound, or drilled,
formed, or molded openings, and which shall have smooth, sharp-edged
openings free of burns, chipped edges, or broken pieces on the interior and
exterior surfaces of the pipe. The pattern of the openings shall be
uniformly spaced around the periphery of the well screen. Compatible slot
sizes of screens and [filter-pack gradations] [surrounding material] shall
be designed by the Contractor and furnished to the Contracting Officer [,
with a representative sample of materials in which the screen is to be
placed]. The plastic pipe screen strength properties shall be equivalent
SECTION 02521
Page 18
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