material shall first be placed to a height of at least 12-inches above the top of
the pipe before excavation.
Pipe trenches shall be made as narrow as practicable and shall not be widened
by scraping or loosening materials from the sides. Every effort shall be made
to keep the sides of the trenches firm and undisturbed until backfilling has
been completed.
If, in the opinion of the Engineer, the sub-grade, during trench excavation, has
been disturbed as a result of rain, surface water runoff or groundwater seepage
pressures, the Contractor shall remove such disturbed sub-grade to a minimum
of 12 inches and replace with crushed stone wrapped in filter fabric. Cost of
removal and replacement shall be borne by the Contractor.
C. BUILDING AND FOUNDATION EXCAVATION:
1.
2.
Excavations shall not be wider than required to set, brace, and remove forms
for concrete, or perform other necessary work.
After the excavation has been made, and before forms are set for footings, mats,
slabs, or other structures, and before reinforcing is placed, all loose or
disturbed material shall be removed from the sub-grade. The bearing surface
shall then be compacted to meet the requirements of this specification.
If, in the opinion of the Engineer, the existing material at sub-grade elevation is
unsuitable for structural support, the Contractor shall excavate and dispose of
the unsuitable material to the required width and depth as directed by the
Engineer. If, in the opinion of the Engineer, filter fabric is required; the
Contractor shall place filter fabric, approved by the Engineer, as per
manufacturer's recommendations. Crushed stone shall then be placed in lifts
and compacted to required densities. Backfill shall be placed to the bottom of
the proposed excavation.
D. EXCAVATION NEAR EXISTING STRUCTURES:
L.
Attention is directed to the fact that there are pipes, manholes, drains, and
other utilities in certain locations. An attempt has been made to locate all
utilities on the drawings, but the completeness or accuracy of the given
information is not guaranteed.
As the excavation approaches pipes, conduits, or other underground structures,
digging by machinery shall be discontinued and excavation shall be done by
means of hand tools, as required. Such manual excavation, when incidental to
normal excavation, shall be included in the work to be done under items
involving normal excavation.
Where determination of the exact location of a pipe or other underground
structure is necessary for properly performing the work, the Contractor shall
excavate test pits to determine the locations.
2019 Sewer Replacement Project Earthwork
Nashua, NH
02300-5
