B. Work damaged by blasting shall be repaired or replaced at the Contractor's expense.
B. Ifrock 1s excavated beyond the limits of payment as specified, or authorized in writing
by the Engineer, the excess excavation, whether resulting from over-breakage or other
causes, shall be backfilled, by and at the expense of the Contractor, as specified below:
In pipe trenches, excess excavation shall be filled with the required material and
compacted in the same manner as specified for the material in the zone around
the pipe under Section 02300 EARTHWORK.
In excavations for structures, excess excavation in the rock beneath foundations
shall be filled with concrete which shall have a minimum 28-day compressive
strength of 3000 psi. Other excess excavation shall be filled with Class B backfill
compacted to a minimum of 92 percent density (ASTM D1557 Method C) as
specified under Section 02300, EARTHWORK.
If the rock below normal depth is shattered due to drilling or blasting operations
of the Contractor, and the Engineer considers such shattered rock to be unfit for
foundations, the shattered rock shall be removed and the excavation shall be
backfilled with concrete as required, except that in pipe trenches crushed stone
may be used for backfill, if approved. All such removal and backfilling shall be
done by and at the expense of the Contractor.
D. When directed by the Engineer, the Contractor shall remove all dirt and loose rock from
designated areas and shall clean the surface of the rock thoroughly to determine
whether seams or other defects exist.
E. | When concrete is to be placed on rock, the rock shall be free of all vegetation, dirt,
sand, clay, boulders, scale, excessively cracked rock, loose fragments, water, ice,
snow, and other objectionable substances.
3.03
VIBRATION AND AIR BLAST
MONITORING:
A. The Contractor shall measure air blast and vibration levels of blasting operations to
assure compliance with all applicable regulations and local permits.
B. Records of each day's air blast and vibration measurements shall be submitted to the
Engineer in writing no later than the start of the next day's work. Records shall include,
as a minimum:
=" Identification of instrument
= Name of observer
=" Name of interpreter
2022 Sewer Replacement Project Rock Structure Excavation and Disposal
Nashua, NH
02324-3
