Backfill shall be deposited in layers of a maximum of 300 mm 12
inch loose thickness, and compacted to 85 percent maximum density
for cohesive soils and 90 percent maximum density for cohesionless
soils. [Water flooding or jetting methods of compaction will be
permitted for granular noncohesive backfill material. Water
jetting shall not be allowed to penetrate the initial backfill.]
[Compaction by water flooding or jetting will not be permitted.]
This requirement shall also apply to all other areas not
specifically designated above.
3.11.2
Backfill for Appurtenances
**************************************************************************
NOTE: The number of days the concrete is allowed to
cure before backfilling the structure will depend on
the type of mix and the concrete strength
requirements specified. Three days would be
considered as a minimum.
**************************************************************************
After the manhole, catchbasin, inlet, or similar structure has been
constructed [and the concrete has been allowed to cure for [_____] days],
backfill shall be placed in such a manner that the structure will not be
damaged by the shock of falling earth. The backfill material shall be
deposited and compacted as specified for final backfill, and shall be
brought up evenly on all sides of the structure to prevent eccentric
loading and excessive stress.
3.12
SPECIAL REQUIREMENTS
Special requirements for both excavation and backfill relating to the
specific utilities are as follows:
3.12.1
Gas Distribution
Trenches shall be excavated to a depth that will provide not less than 450
mm 18 inches of cover in rock excavation and not less than 600 mm 24 inches
of cover in other excavation. Trenches shall be graded as specified for
pipe-laying requirements in Section 02556A GAS DISTRIBUTION SYSTEM.
3.12.2
Water Lines
**************************************************************************
NOTE: Minimum depth of cover will be that required
for frost penetration in the region and for safe
operation of the utility. For fire protection yard
mains, reference is made to NFPA 24 for recommended
depth of cover.
**************************************************************************
Trenches shall be of a depth to provide a minimum cover of [_____] meters
feet from the existing ground surface, or from the indicated finished
grade, whichever is lower, to the top of the pipe. [For fire protection
yard mains or piping, an additional [_____] millimeters inches of cover is
required.]
3.12.3
Heat Distribution System
Initial backfill material shall be free of stones larger than 6.3 mm 1/4
SECTION 02300
Page 35
Previous Page
