S3.1. GENERAL
The Contractor shall design, construct and maintain all temporary diversion and protective works and dewatering systems that are necessary to protect the various parts of the Works from water originating from any source.
Diversion and protective works shall be located such that there is no encroachment on any area required for construction of the Works.
Control of water shall at all times be subject to the approval of the Engineer with regard to sufficiency of measures taken and environmental protection.
On completion of the Works all diversion and protective works and dewatering systems shall be removed and disposed of so as not to interfere in any way with the operation or usefulness of the Works, and the Site restored in a manner to give a sightly appearance.
S3.2. RESPONSIBILITY FOR WORKS
The Contractor shall be fully responsible for any damage or delay to the Works caused by failure of the diversion and protective works and/or dewatering installations, and shall indemnify the Employer against claims by landholders or other persons arising out of any such failure.
The Contractor shall be responsible for, and shall repair or reinstate at its expense, any damage to any part of the Works caused by the failure of the diversion and protective works and/or dewatering installations.
S3.3. WATER CONTROL PLAN
At least 28 days before commencing any construction work, the Contractor shall submit to the Engineer a detailed Water Control Plan describing the proposed methods for control of water.
Diversion of, or interference with, the natural flow of rivers or drainage channels on the Site for any purpose shall be subject to approval.
S3.4. SURFACE EXCAVATIONS
The Contractor shall take all necessary steps to ensure that any water entering any surface excavation does not endanger the stability of the surface excavation at any time.
The Contractor shall ensure that no concentrations or accumulations of water occur either within or around or above the area of any open excavation that may affect the safety of the excavation.
Where excavations are not self-draining, sufficient pumps and sumps shall be installed to keep the water level in such sumps at least 0.5 m below the lowest excavated surfaces for as long as required for construction of the Works. Standby pumps shall be readily available in case of breakdowns.
S3.5. NOT USED S3.6. NOT USED
S3.7. WATER CONTROL DURING CONCRETING
All water which could flow into an area to be concreted shall be diverted clear of the area. Water arising within the area to be concreted shall be piped or pumped clear of the area.
Republic of the Philippines Department of Public Works and Highways Pasig-Marikina River Channel Improvement Project (Phase II) - Contract Package No. 2
S3-2 Specification – Water Control Draft 26/11/12
Pumping shall be done in such a manner as to prevent any of the concrete materials being carried away.
No pumping shall be done during the placing of concrete, or for a period of 24 hours thereafter, unless it is done from a suitable sump separated from the concrete work by a watertight wall.
S3.8. COFFERDAMS
Cofferdams shall be constructed where necessary to protect concrete work against damage from a sudden rise of the river water level, to allow construction of parts of the Works that are below water level and to prevent erosion of embankment foundations.
Cofferdams shall be founded well below the bottom of the footings or embankment toes, constructed to a height sufficient to seal off all water, and shall be well braced and as watertight as practicable. Sufficient clearances shall be maintained between the outside line of footings or walls and the interior sides of cofferdams to provide space for formwork and to permit pumping outside the forms. Excavation and backfilling to provide clearances outside the limits specified in Section S4 [Excavation and Earthworks]
of these Specifications shall be at the Contractor’s cost.
No shoring that will induce stress, shock, or vibration in any part of the Permanent Works will be permitted. Cross struts or bracing shall not extend into the substructure without written permission from the Engineer.
Pumping to dewater a sealed cofferdam shall not commence until the seal has set sufficiently to withstand the hydrostatic pressure.
After the completion of the substructure or embankment to a level where protection is no longer necessary, the cofferdams shall be removed in such manner as not to disturb or mar the finished work.
After removal of cofferdams, the area shall be cleaned of debris and other objectionable material. All temporary fills shall be excavated and disposed of as approved.
S3.9. MEASUREMENT AND PAYMENT
Separate payment will not be made for water control and the entire cost of this work shall be deemed to be included in the various rates and prices in the priced Bill of Quantities.
Republic of the Philippines Department of Public Works and Highways Pasig-Marikina River Channel Improvement Project (Phase III) - Contract Package No. 2
Specification – Excavation and Earthworks Draft 07/03/13 S4-i
CONTENTS
S4. EXCAVATION AND EARTHWORKS 4-1
S4.1. GENERAL 4-1
S4.2. STANDARDS 4-1
S4.3. NOT USED 4-1
S4.4. CLEARING, GRUBBING AND STRIPPING 4-1
S4.5. REMOVAL AND/OR RELOCATION OF EXISTING STRUCTURES 4-1
S4.6. EXCAVATION - GENERAL 4-2
S4.7. NOT USED 4-3
S4.8. EXCAVATION FOR STRUCTURES 4-3
S4.9. NOT USED 4-4
S4.10. EMBANKMENTS - GENERAL 4-4
S4.11. DIKE EMBANKMENTS 4-6
S4.12. NOT USED 4-7
S4.13. NOT USED 4-7
S4.14. NOT USED 4-7
S4.15. NOT USED 4-7
S4.16. RANDOM BACKFILL 4-7
S4.17. BACKFILLING OF PIPE TRENCH 4-7
S4.18. DREDGING 4-8
S4.19. DISPOSAL OF DREDGED MATERIAL 4-10
S4.20. DISPOSAL AND STOCKPILING OF EXCAVATED SURFACE MATERIALS 4-12
S4.21. MEASUREMENT AND PAYMENT 4-13
Republic of the Philippines Department of Public Works and Highways Pasig-Marikina River Channel Improvement Project (Phase III) - Contract Package No. 2
Specification – Excavation and Earthworks Draft 07/03/13 S4-1