Specs

Bridgestone Retail Operations, LLC
PROJECT MANUAL
Version: January 2012
1. All unstable soil shall be removed to a depth of 2 feet below bottom of pipe for pipe 2
feet or more in diameter, and to a depth equal to the diameter of pipe for pipe less
than 2 feet in diameter.
2. Such excavation shall be carried at least one foot beyond the horizontal limits of the
pipe on all sides. All unstable soil so removed shall be replaced with suitable stable
material, placed in uniform layers of suitable depth as directed by the Engineer, and
each layer shall be wetted, if necessary, and compacted by tamping as required to
provide a stable foundation for the structure.
3.11 UNYIELDING TRENCH BOTTOM:
A. When the soil encountered at the established bedding grade is ledge rock, rocking or gravelly
soil, hard pan or other unyielding material, such materials shall be removed prior to bedding
the pipe. These materials shall be excavated for a minimum of 6 inches below the bottom
of the pipe and shall be replaced with crushed stone embedment.
3.12 SHAPING TRENCH BOTTOM:
A. The bottom of the trench shall be undercut for bedding to support the bottom quadrant
uniformly and for its entire length. Provide bell holes for couplings. The pipe shall be bedded
in a foundation of stable material as shown in the project drawings and accurately shaped
to fit the lower part of the pipe exterior.
3.13 BACKFILL MATERIAL:
A. General: Unless shown otherwise on the drawings, suitable granular material chosen from
the excavation shall be used for final backfill. The granular material chosen shall be free of
large lumps, or clods, which will not readily break down under compaction. Backfill material
shall be free of vegetation or other extraneous material. Material will be subject to approval
by the Engineer. In areas not under existing or proposed pavement, the last 6 inches of
backfill shall be topsoil.
B. Select Backfill Material: When "select" backfill material is shown on the drawings, it shall be
granular in nature, free of large clods, and have a plasticity index (P.I.) of less than 15.
3.14 INITIAL BACKFILL:
A. Initial backfill is defined as that granular backfill from the bottom of the trench to 1 foot above
the top of the pipe and shall be select.
B. The Contractor shall place initial granular backfill bedding in maximum 8-inch layers (loose
measure) and mechanically compact it to a density between 90% and 95% of the maximum
density as determined by ASTM D-698 with a moisture content near optimum.
C. Granular backfill below the top of the pipe shall be placed and compacted along the sides of
the pipe equally to prevent strain on or displacement of the pipe.
3.15 FINAL BACKFILL:
A. General: Final backfill is defined as that granular backfill from 1 foot above the top of the pipe
to finished subgrade, pavement underside or ground line. In areas not under proposed
pavement, where the site soils are not granular, backfill with granular material and the last 6
inches of backfill shall be topsoil. See project drawings for special requirements under
sidewalks and paved areas.
PIPE TRENCH EXCAVATION AND BACKFILL 02226 - Page 3 of 4