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1 Handholes/PulI Boxes High density polyethylene
structural foam vaults with external horizontal and vertical ribbing. HDPE will
not absorb moisture and is impervious to chemicals found in the underground
environment. Installations indicated, are from road shoulder back to greenway.
Highway installations contra-indicated, proper concrete chambers should be used
adhering to department of transportation load ratings.
Your Engineering Design department should select the
appropriate handhole, vault or manhole consistent with this guideline.
1.1 The following installation instructions apply
to the following size range.
1.2 24” x 24” through 36” x 60”. This applies to
Handholes/Pull Boxes from 24” up to 4 feet (1 .2 meter) in depth.
1.3 Prepare the hole by digging a pit 8” to 10”
deeper than the overall height of the Handholes/Pull Boxes. The length and
width of the hole should be determined by adding 12” to 16” to the overall
length and width of the Handholes/Pull Boxes.
1.4 Place 10” to 12” of crushed rock evenly
across the bottom of the excavated hole. The compacted material should be
leveled so the top of the Handhole/Pull Box is flush to the grade. Work the box
into the gravel 1” to 2” at the time of leveling. NOTE: Use a classified rock
size of 3/4” and smaller to ensure proper drainage.
1.5 Replace the lid prior to backfilling.
1.6 Backfilling may be accomplished using the
excavated materials.
1.7 Place the backfill into the hole in 12”
increments and compact. Manual compaction is desirable to ensure filling space
between ribs. This step assures locking the vault in the ground preventing
upheaval in high water table areas.
1.8 Vault “Grass Area” installation — Grass Area
describes non-traffic areas separated from roadways by a curb or other
permanent barrier where foot traffic is expected.
1.8.1 Continue backfilling in 12” increments and
compaction until backfill is at grade.
1.9 Vault “Sidewalk or Footway” installation —
Sidewalk or Footway installation provides for safe usage under incidental motor
traffic.
1.9.1 Backfill in 12” increments to within 8” of
the top of Handhole/Pull Box.
1.9.2 Dig out the top 8” to provide for forming a
12” wide collar surrounding the handhole.
1.9.3 Vibrate concrete to release entrapped air
to prevent voids.
1.10 Vault “Hidden” Installation. This method,
for burial below grade, is useful in shoulder or off-road installations for
cable access and prevention of vandalism and safety from vehicular traffic.
1.10.1 Follow instructions 1.3 through 1.8 except
that the excavation will start 36” deeper than flush with grade installations.
1.10.2 During the backfilling operation,
continue in 12” increments with manual compacting. Proper compaction essential
in the 36” above the Handhole/ Pull Box.
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