In all excavation areas, the Contractor shall strip the surface topsoil layer and
underlying subsoil layer separate from underlying soils. In paved areas, the
Contractor shall first cut pavement as specified in paragraph 3.02 B.1 of this
specification, strip pavement and pavement sub-base separately from
underlying soils. All excavated materials shall be stockpiled separately from
each other within the limits of work.
The Contractor shall follow a construction procedure, which permits visual
identification of stable natural ground. Where groundwater is encountered, the
size of the open excavation shall be limited to that which can be handled by the
Contractor's chosen method of dewatering and which will allow visual
observation of the bottom and backfill in the dry.
The Contractor shall excavate unsuitable materials to stable natural ground
where encountered at proposed excavation sub-grade, as directed by the
Engineer. Unsuitable material includes topsoil, loam, peat, other organic
materials, snow, ice, and trash. Unless specified elsewhere or otherwise
directed by the Engineer, areas where unsuitable materials have been
excavated to stable ground shall be backfilled with compacted special bedding
materials or crushed stone wrapped all around in non-woven filter fabric.
TRENCHES:
1.
Prior to excavation, trenches in pavement shall have the traveled way surface
cut in a straight line by a concrete saw or equivalent method, to the full depth
of pavement. Excavation shall only be between these cuts. Excavation support
shall be provided as required to avoid undermining of pavement. Cutting
operations shall not be done by ripping equipment.
Trenches shall be excavated to such depths as will permit the pipe to be laid at
the elevations, slopes, and depths of cover indicated on the Drawings. Trench
widths shall be as shown on the Drawings or as specified.
Where pipe is to be laid in bedding material, the trench may be excavated by
machinery to, or just below, the designated sub-grade provided that the
material remaining in the bottom of the trench 1s not disturbed.
If pipe is to be laid in embankments or other recently filled areas, the fill
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.
Excavations shall not be wider than required to set, brace, and remove forms
for concrete, or perform other necessary work.
02300-6
