3.7.2
Backfilling Pipe in Fill Sections
For pipe placed in fill sections, backfill material and the placement and
compaction procedures shall be as specified below. The fill material shall
be uniformly spread in layers longitudinally on both sides of the pipe, not
exceeding 150 mm 6 inches in compacted depth, and shall be compacted by
rolling parallel with pipe or by mechanical tamping or ramming. Prior to
commencing normal filling operations, the crown width of the fill at a
height of 300 mm12 inches above the top of the pipe shall extend a distance
of not less than twice the outside pipe diameter on each side of the pipe
or 4 m, 12 feet, whichever is less. After the backfill has reached at
least 300 mm 12 inches above the top of the pipe, the remainder of the fill
shall be placed and thoroughly compacted in layers not exceeding [_____] mm
inches.
3.7.3
Movement of Construction Machinery
When compacting by rolling or operating heavy equipment parallel with the
pipe, displacement of or injury to the pipe shall be avoided. Movement of
construction machinery over a culvert or storm drain at any stage of
construction shall be at the Contractor's risk. Any damaged pipe shall be
repaired or replaced.
3.7.4
Compaction
3.7.4.1
General Requirements
Cohesionless materials include gravels, gravel-sand mixtures, sands, and
gravelly sands. Cohesive materials include clayey and silty gravels,
gravel-silt mixtures, clayey and silty sands, sand-clay mixtures, clays,
silts, and very fine sands. When results of compaction tests for
moisture-density relations are recorded on graphs, cohesionless soils will
show straight lines or reverse-shaped moisture-density curves, and cohesive
soils will show normal moisture-density curves.
3.7.4.2
Minimum Density
**************************************************************************
NOTE: For culverts or storm drains installed
beneath structures (including embankments) that have
critical stability requirements or settlement
limitations, the maximum density requirements should
be increased as necessary. If only a cohesive soil
or only a cohesionless material will be used as
backfill, the inapplicable value will be deleted.
**************************************************************************
Backfill over and around the pipe and backfill around and adjacent to
drainage structures shall be compacted at the approved moisture content to
the following applicable minimum density, which will be determined as
specified below.
a.
Under airfield and heliport pavements, paved roads, streets,
parking areas, and similar-use pavements including adjacent
shoulder areas, the density shall be not less than 90 percent of
maximum density for cohesive material and 95 percent of maximum
density for cohesionless material, up to the elevation where
requirements for pavement subgrade materials and compaction shall
SECTION 02630
Page 38
Previous Page
