NATIONAL ALUMINIUM COMPANY LIMITED - Rites

or as directed by the Engineer. The bottom of all excavations shall be trimmed to required
levels and when excavation is carried below such levels by error, it shall be brought back to
the specified level by filling with concrete of nominal mix 1 : 3 : 6 ( (cement: cement: coarse sand: 40
mm down aggregates ), as directed by the Engineer. The Contractor shall ascertain for
himself the nature of materials to be excavated and the difficulties, if any, likely to be
encountered in executing this work. Cofferdams, sheet ppiling,
iling, shoring, bracing to maintain
suitable slopes, draining etc. shall be provided and installed by the contractor, to the
satisfaction of the Engineer. Surplus excavated materials shall be disposed off by the
contractor at locations within plant boundary wall as directed by the engineer. The
Contractor shall have to constantly pump out any water collected in excavated pits and
other areas due to rain water, springs etc. and maintain dry working conditions at all times
until the excavation, placement of reinforcement, shuttering, concreting, Backfilling is
completed. The Contractor shall remove all slush/muck from the excavated areas to keep
the work area dry. The Contractor, if required, shall employ sludge pumps, for this purpose.
15.2 Excavation avation in rock
For the work of excavation in rock, Contractor shall engage specialized agency having
experience of excavation in rock involving wedging and blasting. The agency shall be subject
to approval of Engineer and the Contractor shall furnish det details ails of relevant experience in
support while seeking approval for the agency agency. Only Control Blasting shall be resort resorted to
with the written permission of the Engineer. In case blasting method can not be adopted
considering the safety aspect of the existing rrail
ail network, buildings, structures etc, hard rock
shall be excavated by using expansive chemical or any other suitable means means. All the
statutory laws, (Explosives Act etc.) rules, regulations, Indian Standards etc. pertaining to the
acquisition, transport, storage, handling and use of explosives etc. shall be strictly followed.
The contractor shall obtain Licenses from Competent Authorities for undertaking blasting
work as well as for procuring, transporting to site and storing the explosives as per
Explosives es Act. The Contractor shall be responsible for the safe transport, use, custody and
proper accounting of the explosive materials. Surplus excavated materials shall be disposed
off by the contractor at locations within plant boundary wall as directed by th the engineer.
The Contractor shall have to constantly pump out any water collected in excavated pits and
other areas due to rain water, springs etc. and maintain dry working conditions at all times
until the excavation, placement of reinforcement, shuttering shuttering, , concreting, backfilling is
completed.
15.3 De-watering watering of Deep Excavations
For deep underground structures like wagon tippler hopper, machinery hatches, tunnels and
underground transfer houses, requiring open excavation with extensive de - watering,
completely letely dry working conditions during excavation, shuttering, placement of
reinforcement, concreting, water proofing of structures, backfilling and any other operation
shall be maintained by suitable de - watering method of suitable capacity.
15.4 Backfilling, ng, Disposal and Stacking of materials
Backfilled earth shall be compacted to minimum 90 % of the standard proctor density at
OMC. Sand filling shall be compacted to minimum 80 % of the relative density. However, the
backfill under the rail lines and roads shall be compacted to minimum 95 % of the standard
proctor density at OMC unless otherwise stated by rail Authorities. The contractor is
required to excavate upto any depth as shown on the drawings or as directed by the
Engineer. Lifting of excavated mate materials rials shall be done either by manual or mechanical or
both means if called for by the Engineer. The disposal / stacking areas for excavated
materials shall be indicated by the Engineer. If directed by the Engineer this material shall be
used directly for filling illing purposes. For leads exceeding 500 m the Contractor shall transport
the excavated materials by mechanical means only and as directed by the Engineer. The
Contractor may be allowed to carry materials through Kuccha roads. Providing and
Technical Specification:Sec-7, Civil
Page 12 of 21