Rev. 1-22-97
BIN-TYPE RETAINING WALL
714-R-003
DESCRIPTION. This work shall consist
of metal bin-type retaining walls constructed in accordance with
these specifications and in conformance with the lines, grades,
and dimensions shown on the plans, or as otherwise directed.
MATERIALS. Metal bin-type retaining
walls shall consist of a plurality of pairs of columns. One
column of each pair is to be in the plane of the pairs of columns
shall be spaced longitudinally with overlapping U-shaped facing
and rear members called stringers, and transversely with
overlapping U-shaped tie members called spacers. The necessary
bolts and appurtenances shall be furnished for complete assembly
of the units into a continuous closed face wall of connected
bins.
The units in the wall shall be in
accordance with the dimensions and gages shown on the plans. The
units shall present a uniform workmanlike appearance when
assembled.
The base metal of the galvanized
sheets shall be in accordance with AASHTO M 218.
The base metal sheets shall be
galvanized on both sides by mean of the not-dip process. A
coating of prime western spelter or equal shall be applied at the
rate of not less than 610 g/m5 (2 oz/sft) of double exposed
surface. If the average spelter coating as determined from the
required samples is less than 610 g/m5 (2 oz/sft), or if one
sample is less than 550 g/m5 (1.8 oz/sft) of double exposed
surface, the lot sampled shall be rejected. The finished sheets
shall be of first class commercial quality, free from injurious
defects, such as blisters, flux, and uncoated spots.
CONSTRUCTION REQUIREMENTS. The wall
members shall be constructed of metal of the gage shown on the
plans, but not less than 16 gage. All units shall be so
fabricated that units of the same nominal size shall be fully
interchangeable. No drilling, punching, or drifting to correct
defects in manufacture will be permitted. All units having
improperly punched holes shall be promptly replaced by the
manufacturer with no additional payment. The ends of all
stringers and spacers shall be bolted to corner columns by means
of connecting channels.
The proper curvature for the face of
a wall constructed on a curve shall be obtained by the use of
shorter stringers in the front or rear panels of retaining walls
as shown on the plans or as otherwise directed.
The wall height and depth may be
varied. Two or more designs of retaining walls may be
incorporated in the same wall by the use of standard split
columns to make the connection on the step-back.
The units shall be erected as shown
on the plans. Members shall be handled carefully and those which
are damaged shall be removed and new members substituted with no
additional payment.
The filling for the interior of the
bin and behind the wall shall be B borrow placed in layers not to
exceed 150 m (6 in.) in thickness and tamped or consolidated as
directed. Compaction by saturation will not be permitted.
Backfilling behind the wall shall progress with the filling of
the bins and shall not be carried ahead of binfill. Existing
slopes, which are shaped so as to cause a wedge action in the
backfill, shall be step-cut or benched before backfilling.
METHOD OF MEASUREMENT. This work will
be measured by the square meter (square foot) of facial area for
each design height and thickness of wall complete in place and
accepted.
BASIS OF PAYMENT. This work will be
paid for at the contract unit price per square meter (square
foot) for retaining wall, bin-type. The B borrow required and
used for backfilling, complete, in place and accepted, will be
paid for at the contract unit price per cubic meter (cubic foot)
for B borrow for structure backfill.
The costs of furnishing, handling,
and installing the metal units including all materials, bolts,
and appurtenances; necessary excavation; and all labor,
equipment, and necessary incidentals shall be included in the
cost of this work.