PACKAGE : I Bid Document VOLUME : II - Public Health Engineering

Where deemed necessary by the Engineer, working drawings and data shall be
submitted for review or approval showing the intended plan for dewatering
operations. Details of locations and capacities of dewatering wells, well points,
pumps, sumps, collection and discharge lines, standby units, water disposal
methods, monitoring and settlement shall be included. These shall be submitted not
less than 30 days prior to start of dewatering operations.
The static water level shall be drawn down to a minimum of 300mm below the
bottom of the excavation so as to maintain the undisturbed state of the foundation
soils and allow the placement of any fill or backfill to the required density. The
dewatering system shall be installed and operated so that the groundwater level
outside the excavation is not reduced to the extent that would damage or endanger
adjacent structures or property.
5.15 Unsound foundations, soft spots.
When the specified levels of trench or structure are reached, the Engineer will
inspect the ground exposed and if he considers that any part of the ground is by its
nature unsuitable, he may direct the Contractor to excavate further and the further
excavation shall be filled with concrete M-10 or river sand. Should the bottom of
any trench or structure excavation, while acceptable to the Engineer at the time of
his inspection subsequently become unacceptable due to exposure to weather
conditions or due to flooding or have become puddled, soft or loose during the
progress of the works, the Contractor shall remove such damaged, softened or
loosened material and excavate further by hand. In this case, the cost of the extra
excavation and of the additional foundation materials required will be the
Contractor's responsibility if necessitated by his negligence.
The omission by the Engineer to give an instruction under this Clause shall not
relieve the Contractor from any responsibility for defect in the works due to the
construction being placed upon an unsuitable formation if prior to the construction
of the work the Contractor shall have failed to call the attention of the Engineer
thereto in writing.
If in the opinion of the Engineer, a formation is unsound as a result of the
Contractor failing to keep the excavation free from water, the Engineer will order
the removal and disposal of the unsound material and filling of the resulting void.
The Contractor shall execute the work as directed and shall have no claim against
the Board for any costs thus incurred.
GTS : General Technical Specification. Page 38