by benching into the slope.
If the material removed from the excavation is suitable for backfill with the
exception that it contains stones larger than permitted, the Contractor has the
option to remove the oversized stones and use the material for backfill or to
provide replacement backfill at no additional cost to the Owner.
The Contractor shall remove loam and topsoil, loose vegetation, stumps, large
roots, etc., from areas upon which embankments will be built or areas where
material will be placed for grading. The sub-grade shall be shaped as indicated
on the Drawings and shall be prepared by forking, furrowing, or plowing so
that the first layer of the fill material placed on the sub-grade will be well
bonded to the sub-grade.
Where called for on the Drawings, Lightweight Fill shall be placed and
compacted as recommended by the manufacturer. The exact number of passes
shall be approved by the Engineer to insure stability of the layer. As soon as
the compaction of each layer has been completed, the next layer shall then be
placed. The Contractor shall take all necessary precautions during construction
activities in operations on or adjacent to the Lightweight Fill to insure that the
material is not over-compacted. Construction equipment, other than for
compaction, shall not operate on the exposed Lightweight Fill. The top surface
of the Lightweight Fill lying directly below the gravel course shall be chinked
by additional rolling of the Lightweight Fill to prevent infiltration of fines.
B. TRENCHES:
l.
Bedding as detailed and specified shall be furnished and installed beneath the
pipeline prior to placement of the pipeline. A minimum bedding thickness shall
be maintained between the pipe and undisturbed material, as shown on the
Drawings.
As soon as practicable after pipes have been laid, backfilling shall be started.
Unless otherwise indicated on the Drawings, select backfill shall be placed by
hand shovel in 6-inch thick lifts up to a minimum level of 12-inches above the
top of pipe. This area of backfill is considered the zone around the pipe and
shall be thoroughly compacted before the remainder of the trench is backfilled.
Compaction of each lift in the zone around the pipe shall be done by use of
power-driven tampers weighing at least 20 pounds or by vibratory compactors.
Care shall be taken that material close to the bank, as well as in all other
portions of the trench, is thoroughly compacted to densities required.
Class B backfill shall be placed from the top of the select backfill to the
specified material at grade (loam, pavement sub-base, etc.). Fill compaction
shall meet the density requirements of this specification.
Water Jetting:
a. Water jetting may be used when the backfill material contains less than
10 percent passing the number 200 sieve, but shall be used only if
approved by the Engineer.
b. Contractor shall submit a detailed plan describing the procedures he
intends to use for water jetting to the Engineer for approval prior to any
2019 CIPP Lining Project Earthwork
Nashua, NH
02300-7
