is required.
Locally available coarse aggregate for concrete will
suffice and may be specified by local gradation and
specification number in lieu of "GW" or "GP."
Maximum size of aggregate should not be more than 25
mm per 300 mm (one inch per foot) of pipe diameter
or 75 mm (3 inches) maximum. Refer to pipe
manufacturer's criteria for more stringent
requirements, if any, on aggregate size and
gradation. On drawings (details), clearly show
where gravel backfill or bedding is required.
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[Bedding shall be of the type and thickness shown.] Initial backfill
material shall be placed and compacted with approved tampers to a height of
at least one foot above the utility pipe or conduit. The backfill shall be
brought up evenly on both sides of the pipe for the full length of the
pipe. Care shall be taken to ensure thorough compaction of the fill under
the haunches of the pipe. Except as specified otherwise in the individual
piping section, provide bedding for buried piping in accordance with AWWA
C600, Type 4, except as specified herein. Backfill to top of pipe shall be
compacted to 95 percent of ASTM D 698 maximum density. Plastic piping
shall have bedding to spring line of pipe. Provide materials as follows:
a.
Class I: Angular, 6 to 40 mm 0.25 to 1.5 inches, graded stone,
including a number of fill materials that have regional
significance such as coral, slag, cinders, crushed stone, and
crushed shells.
b.
Class II: Coarse sands and gravels with maximum particle size of
40 mm 1.5 inches, including various graded sands and gravels
containing small percentages of fines, generally granular and
noncohesive, either wet or dry. Soil Types GW, GP, SW, and SP are
included in this class as specified in ASTM D 2487.
c.
Clean, coarse-grained sand classified as [_____] in accordance
with Section [_____], [gradation [_____] of the [DOT] [State
Standard] or [SW] [or] [SP] by ASTM D 2487 for [bedding] [and]
[backfill] [as indicated]].
d.
Clean, coarsely graded natural gravel, crushed stone or a
combination thereof identified as [_____] in accordance with
Section [_____], [gradation [_____] of the [DOT] [State Standard]]
or having a classification of [GW] [GP] in accordance with ASTM D
2487 for [bedding] [and] [backfill] [as indicated]. [Maximum
particle size shall not exceed [75] [_____] mm [3] [_____] inches.]
3.11.1.4
Final Backfill
The remainder of the trench, except for special materials for roadways,
railroads and airfields, shall be filled with satisfactory material.
Backfill material shall be placed and compacted as follows:
a.
Roadways, Railroads, and Airfields: Backfill shall be placed up
to the required elevation as specified. Water flooding or jetting
methods of compaction will not be permitted.
b.
Sidewalks, Turfed or Seeded Areas and Miscellaneous Areas:
SECTION 02300
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