Construction shall be of reinforced concrete, plain concrete, brick,
precast reinforced concrete, precast concrete segmental blocks,
prefabricated corrugated metal, or bituminous coated corrugated metal;
complete with frames and covers or gratings; and with fixed galvanized
steel ladders where indicated. Pipe studs and junction chambers of
prefabricated corrugated metal manholes shall be fully bituminous-coated
and paved when the connecting branch lines are so treated. Pipe
connections to concrete manholes and inlets shall be made with flexible,
watertight connectors.
3.5.2
Walls and Headwalls
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NOTE: Dry-stone masonry may be specified and used
for crib construction and/or sloping retaining walls
that will sustain little or no earth pressure.
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Construction shall be as indicated.
3.6
STEEL LADDER INSTALLATION
Ladder shall be adequately anchored to the wall by means of steel inserts
spaced not more than 1.83 m 6 feet vertically, and shall be installed to
provide at least 152 mm 6 inches of space between the wall and the rungs.
The wall along the line of the ladder shall be vertical for its entire
length.
3.7
BACKFILLING
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NOTE: The thickness of layers of backfill and the
degree of compaction required to prevent undesirable
settlement should be determined by soil conditions
and the job compaction requirements. When rigid
pipe is to be placed under high fills, the imperfect
trench method of installation may be specified.
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3.7.1
Backfilling Pipe in Trenches
After the pipe has been properly bedded, selected material from excavation
or borrow, at a moisture content that will facilitate compaction, shall be
placed along both sides of pipe in layers not exceeding 150 mm 6 inches in
compacted depth. The backfill shall be brought up evenly on both sides of
pipe for the full length of pipe. The fill shall be thoroughly compacted
under the haunches of the pipe. Each layer shall be thoroughly compacted
with mechanical tampers or rammers. This method of filling and compacting
shall continue until the fill has reached an elevation of at least 300 mm
12 inches above the top of the pipe. The remainder of the trench shall be
backfilled and compacted by spreading and rolling or compacted by
mechanical rammers or tampers in layers not exceeding [_____] mm inches.
Tests for density shall be made as necessary to ensure conformance to the
compaction requirements specified below. Where it is necessary, in the
opinion of the Contracting Officer, that sheeting or portions of bracing
used be left in place, the contract will be adjusted accordingly.
Untreated sheeting shall not be left in place beneath structures or
pavements.
SECTION 02630
Page 37
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