6.2.1 - Civil and Structural Works

Design, Construction, Installation, Testing & Commissioning of Wastewater Treatment Plant for Phase II Development of Semakau Landfill

6.2.1 - 1

6.2.1 CIVIL AND STRUCTURAL WORKS 6.2.1.1 General

This section of the Specification relates to all civil and structural works required under the Contract. The particular requirements shall complement the general requirements in Section 6.3.3.

6.2.1.2 Scope of Works

The Scope of Works under this Contract for the Civil & Structural Works shall include design, procurement, setting out, construction, installation, testing, commissioning, maintenance and hand over of the civil and structural works associated with the entire Works as described in this Specification. The Contractor shall be responsible for the planning and detailed programming for all the construction activities and his agents, subcontractors and suppliers.

6.2.1.2.1 Contractor’s Responsibility for Design and Submissions to Regulatory Authority and Technical Departments (a) The scope of works also includes the detailed design and

submission to relevant authorities in accordance with the Building Control Act for the civil and structural layout of the Wastewater Treatment Plant and the associated infrastructure works. This includes the structural designs of all buildings and associated facilities, the embankment extension from the perimeter bund, shore protection, silt curtain, the access bridge, roads, drains and pipework and all relevant authority submissions for Building and Structural Plans Approvals. The design and construction of the floating platform is also part of the civil scope but this is specified in Specification 6.2.2.

(b) The Contractor shall engage a Professional Engineer registered in

the branch of civil or structural engineering with a practising certificate under the Professional Engineers Act (Cap.253) Singapore (PE Singapore) to act as the Qualified Person (QP) for geotechnical, civil and structural works pertaining to the permanent works. The Contractor’s QP shall prepare plans, submit plans to the relevant authorities and supervise the structural works. The QP shall engage a Qualified Site Supervisor (QSS) to supervise the architectural, civil works, underground building works and structural works respectively. The QSS (Resident Engineer and/or Resident Technical Officer) is(are) required to be appointed under Section 10 of the Building Control Act and shall supervise the structural or geotechnical aspects of the building works on behalf the QP. Appointment and the cost of the QP and QSS and all submission fees shall be deemed to be included in the Contractor’s price for this Contract.


6.2.1 - 2

(c) If an Accredited Checker (AC) and/or specialist AC e.g. AC(Geo) is/are required to check the structural and/or geotechnical aspects of underground building plans and works, then the cost and appointment of the AC will be by the Employer.

(d) In addition to the submissions required for regulatory approval, the

Contractor shall submit the proposed civil and structural layouts plans, including calculations and any testing reports to the S.O. for review and approval prior to submission to the Regulatory Authorities. The Contractor shall allow for coordination meetings and assistance to the S.O. for any pre-consultation with the relevant authorities for approval of the works.

(e) Design and Submission to Fire Safety & Shelter Department

SCDF, FSSD commented that submission to FSSD is not required in their reply to a pre-consultation for the proposed wastewater treatment plant on floating platform at Semakau landfill. The Consultation Reply Letter (dated 11-Jun-2013) is appended to this Section for the Contractor’s reference only.

(f) It shall be the Contractor and his QP’s responsibility to consult

FSSD independently and check whether FSSD’s approval is required for the building plans proposed and prepared by the Contractor’s QP. If FSSD’s approval is not required for the building plan prepared by the Contractor’s QP after consulting FSSD, basic fire safety equipments shall be provided around the wastewater treatment plant covered under Specification for Mechanical works. The Contractor shall make provisions for works related to fire safety and price in the Contract. There shall be no additional payment to the Contractor resulting from any requirements by FSSD to approve the building plans prepared by the Contractor’s QP and all related fire safety works to comply with FSSD requirements including submission(s), fees and appointment of Registered Inspector(RI) (Arch) and RI(M&E).

(g) The Semakau Landfill is also occupied by other contractors

throughout the duration of the contract. The Contractor planning and programming the works should take into consideration the maintenance and usage of the access for the delivery and refuse trucks which regularly enter the delivery bays.

6.2.1.2.2 Civil and Structural Work Components

The Works involve the design, construction and completion of the following main buildings, structures and infrastructure works as listed below and shown on drawings:

(a) Slope stability and settlement analysis arising from the formation

of embankment extension on existing perimeter bund;


6.2.1 - 3

(b) Floating platform to support the Wastewater Treatment plant (refer to Specification for Floating Platform);

(c) Access bridge for vehicular access between floating platform and

the perimeter bund; (d) Structural support for access bridge which includes A-frame and

wire-rope suspension system or substructure foundation to support the access bridge on the perimeter bund;

(e) Mooring support for floating platform (refer to Specification for

Floating Platform); (f) Silt curtain and erosion control measures; (g) Structural steel roofs over all chemical (Na2S, Polymer, FeCl3,

H2SO4 and NaOH) storage tanks and dosage system; (h) Electrical and Control Room and the adjoining Store Room unit; (i) All bund walls, sumps, drains and channels required in the

treatment area; (j) Steel leg supports, plinths or skids for elevated tanks and

equipment; (k) Access staircase and platforms around all tanks; (l) Pipe laying works and pipe supports within and around the floating

platform including the discharge pipe between the wastewater treatment plant and the discharge point into the sea;

(m) Discharge pipe at sea (pipe exit level to be +0m CD); (n) Access platform structure linking to existing bund to the sea for

mounting and maintenance of Level Indicator Transmitter (LIT); (o) Access platform structure linking to existing bund to the Phase II

Cell for mounting and maintenance of LIT; (p) Protection of the existing shore slope including the geo-membrane

and geo-fabric; (q) Road work, traffic signs, ramps and road markings.

6.2.1.2.3 Civil Work Responsibility

The works shall include but not limited to: (a) Site clearance, including the cutting and removal of any existing

plants and vegetation that is necessary for construction of the new


6.2.1 - 4

structures and infrastructure. All surplus material shall be removed from the site and taken to an approved dumping ground. This site clearance works shall be for the site area and include the Contractor's work area identified on the Location Plan on the drawings;

(b) Earthworks, involving the general excavation and where

necessary backfilling with engineering fill to the proposed platform levels for buildings, structures and road works, and also removal of the excavated spoil off the site to approved dumping grounds;

(c) Earthworks, involving partial removal of the existing shore slope

materials including rocks, geo-membrane and geo-fabric and where necessary reinstatement with the same materials to the original slope formation, and also removal of the excavated spoil off the site to approved dumping grounds;

(d) Design calculations on the stability of the existing shore slope

affected by the proposed works and the proposed embankment works shall be carried out by the Contractor’s QP(Geotechnical) and reviewed by an Accredited Checker or Specialist Accredited Checker as required by the Building Control Act;

(e) Installation of ground monitoring instruments, as prescribed by the

Contractor’s QP(Geotechnical) and reviewed by an Accredited Checker or Specialist Accredited Checker as required by the Building Control Act, for the stability of the shore slope, not limited to ground settlement markers, inclinometers, tiltmeters etc at required locations, and including the monitoring of the readings of the instruments at the specified intervals;

(f) Design by Contractor’s QP, an A-frame and wire rope support

system for the access bridge or a foundation system to support the access bridge on the perimeter bund and the proposed floating platform;

(g) Design by Contractor’s QP, supply and construct all proposed

reinforced concrete substructures and superstructures, including all necessary incidental earth excavation and backfilling with approved materials;

(h) Design by Contractor’s QP, supply, fabricate and construct all

structural steelworks proposed, including the preparation of the steel surfaces to receive the specified corrosion protection system, and application of the corrosion protection system;

(i) Design by Contractor’s QP, supply, fabricate and construct all

proposed normal grade aluminium works and marine grade aluminium structural works, including details to isolate aluminium from other metals which may cause galvanic corrosion to aluminium. Marine grade aluminium which is submerged in water shall be coated with specified corrosion protection system after


6.2.1 - 5

preparation of the aluminium surfaces. Where it is impossible to achieve isolation, sacrificial zinc anodes shall be used;

(j) Design by Contractor’s QP, supply and construct all necessary

building works, eg the Electrical and Control Room, including installation of doors and windows;

(k) Design by Contractor’s QP, supply, fabricate and construct of

metal roofing and all necessary metal flashings and connections; (l) Design by Contractor’s QP, supply, fabricate and construct all

ancillary structures, such as bund walls, pipe bridge, elevated platforms around tanks and equipments, elevated vehicular access platform ramp for pipe(s) laid on deck level, staircases, ladders, bollards including substructures, vehicular impact guardrails, skid supports for tanks, railings, frame support with hoist beam for lifting devices, valve chamber for discharge pipeline, security gates, height limit barrier including substructure;

(m) Design by Contractor’s QP, supply and construct Platform structures for LIT with minimum 1.0m wide access clearance, including security gates, hand railings, deck plates or slabs and foundations, for the mounting and maintenance for Level Indicator Transmitters (LIT)s;

(n) Supply and construct miscellaneous reinforced concrete works

associated with the installation of thrust block, anchor blocks, pipe trench and outfall pipe;

(o) Design, supply, fabricate and erection of all necessary steel pipe

supports; (p) Design, supply, fabricate and installation of steel brackets or

connection plates, connection bolts and welding necessary for the installation of structural steel works, all aluminium works, ancillary works and miscellaneous works as described in the previous items;

(q) All necessary tests for welding connections in structural steel

works and structural aluminium works using marine grade aluminium;

(r) All necessary tests on any protective coatings not limited to paint

as required under the protective coating specifications such that the manufacturer for the specified protective coating remain satisfied to warranty the applied protective coating;

(s) All necessary tests including hydrostatic testing of all water

retaining structures and pipelines;


6.2.1 - 6

(t) Erosion Control Measure (ECM) plan design by Contractor’s QECP, supply and construct all necessary as reflected in the ECM plan;

(u) Design by the Contractor’s QECP, supply, fabricate and install

primary and secondary silt curtains which will form part of the permanent works on the Phase II Cell. The curtains shall be at least 50m away from the submersible pumps mounted on the floating platform;

(v) All necessary topographical survey and hydrographical survey that

are necessary for the Contractor to carry out his work but not limited to the area within the site boundary;

(w) Ground and soil investigation works, including boring works if

required, for the design and the construction of the extended shore slope by building on existing perimeter bund and the sea beds on both sides of the perimeter bund etc. that are necessary for the Contractor’s QP designs. The Contractor shall note that dredging works is not allowed;

(x) Design and construction of road and drainage works necessary for

the temporary site offices during the construction period; (y) All regulatory authority submissions, licensing, permit and

certification required to design, construct, transport and position the floating platform in Semakau Landfill area;

(z) All designs by Contractor’s QP and building works which requires

regulatory authority and technical department submissions approval and Permit including obtaining the Certificate of Statutory Completion for the structural and building works.

The Contractor shall note in his designs the meteorological ocean conditions at Semakau Landfill which is covered under the Specification 6.2.2.3.2 for the Floating Platform. All proposed structural and miscellaneous elements, including the metal roofs, louver, building(s), pipe and tank supports, access bridge, platform structure for LIT, silt curtain, connections etc., shall be adequately designed in strength, stability and durability against the environmental forces that the elements will be reasonably exposed to.

6.2.1.3 Method Statements and Submissions

(a) The Contractor shall submit detailed method statements, design calculations and other supporting documents to the S.O. for areas of critical work. The requirement for these method statements is detailed in the Specification and is summarised in the list below. The S.O. may also request additional method statements or supporting documents on any aspect of the Works where further clarification is required. The Contractor shall provide these for


6.2.1 - 7

approval in good time before the relevant construction work begins. Approval of a method statement by the S.O. will in no way relieve the Contractor of responsibility for the successful completion and functionality of the Works in compliance with the Specification. There shall be no additional cost to the Employer due to the Contractor providing additional method statements or supporting documents.

(b) Summary of method statements and supporting documents

required:

(1) Details of reclamation work and formation of embankment/ perimeter bund extension including details of fill, geofabric layer and rocks;

(2) Details of types and models of earth moving equipments to be deployed on site;

(3) Details of any demolition/rock removal works and impact/mitigation measures to ensure integrity of existing shore slope;

(4) Details of proposed shore slope protection; (5) Details on the sources of supply for Earthworks; (6) Details of topographical and hydrographical surveys; (7) Details, stability and structural calculations for design of

floating platform (covered under Particular Specification 6.2.2);

(8) Details and structural calculations for marine grade aluminium access bridge between floating platform and embankment/ perimeter bund;

(9) Details and structural calculations for mooring system for floating platform;

(10) Setting out; (11) Details and structural calculations for structural steel roofs

over all chemical storage tanks and dosage systems, including fabrication details and steel connection details;

(12) Details of proposed metal roofing systems, flashings, including all connection details;

(13) Details of FRP protection coating for chemical bunds containing respective type chemical storage tanks;

(14) Details of epoxy coating for bund containing generators and fuel tanks;

(15) Details and structural calculations for pipe bridge(s); (16) Detail layout plans and structural calculations for all

elevated platforms around equipments, tanks etc including access/exit locations, staircases, floor plates or mesh and handrails;

(17) Concrete mix design ; (18) Details of architectural design and structural designs

including drawings and structural calculations for the electrical and control room and adjoining store room unit;

(19) Details of steel frames or skid support for respective tanks and equipment (eg. pumps);


6.2.1 - 8

(20) Details and structural calculations for steel frames supporting monorail beams and hoists;

(21) Details for the installation and testing of all lifting devices, including the loads to be imposed on the structural steel roofs;

(22) Details of steel supports and thrust restraints for piping; (23) Details and design calculations for elevated platforms and

walkways; (24) Details and structural calculations for marine grade

aluminium chequered plate ramp; (25) Details and structural calculations for vehicle bollards and

vehicular impact guardrails; (26) Details and structural calculations for anodised aluminium

railings; (27) Details and structural calculations for reinforced concrete

block or steel structures on the perimeter bund to support the access bridge;

(28) Details of security gate at access bridge; (29) Details of height barrier structure with suspended height

clearance bar and height limit sign; (30) Details of the discharge pipeline from the wastewater

treatment plant to the sea; (31) Details and structural calculations for pipe supports for

discharge pipeline and other pipelines along the edge of floating platform;

(32) Details of valve chamber(s) for discharge pipeline; (33) Details and structural calculations for pipe supports along

access bridge; (34) Details and calculations for trenching works or temporary

slope formation along the embankment and perimeter bund, including any reinstatement of any existing rocks , existing geo-membrane, existing geo-fabric and existing subgrade at the turfing and cart track;

(35) Details of concrete cover all surround to discharge pipe along embankment or perimeter bund surface;

(36) Details of anchor blocks with stainless steel saddles for discharge pipe submerged in water;

(37) Details and calculations for outfall structure connected to the discharge pipe at the sea;

(38) Details and structural calculations for marine grade aluminium Platform structures for the mounting and maintenance of Level Indicator Transmitters (LIT)s secured in stainless steel box;

(39) Details and structural calculations for concrete anchor block for Platform structure for LIT;

(40) Proposed location of off-site disposal point for surplus or unsuitable material including supporting documentation for licensed disposal;

(41) Detail plans and calculations by QECP for Erosion Control Measures;


6.2.1 - 9

(42) Detail plans, calculations by QECP and execution plans for the installation of silt curtain around the floating platform for long-term use;

(43) Details for all painting and protective coatings for structures;

(44) Details for all painting, protective coatings and other protection measures (eg. sacrificial anodes) to the external hull of floating platform;

(45) Details of anti-slip paint if the deck for the floating platform is constructed of steel;

(46) Details of road or lane marking and road signs on floating platform deck;

(47) Details of signages specific to respective equipments, tanks, electrical and control room, safe working load (SWL) for all lifting hoists, warning, danger signs, exit signs, allowable imposed load (and vehicle tonnage) on access bridge; allowable imposed loading on floating platform, roofs and Platform structures for LIT respectively, height limit signs, speed limit signs;

(48) Protection of existing underground services within the proposed location of the works;

(49) Diversion and laying of services affected by proposed works within the proposed site;

(50) Construction of all civil and structural works including reinforced concrete and steel structural buildings and elements as shown on Drawings;

(51) Casting and installation of precast concrete structural elements if any, including full shop drawings;

6.2.1.4 Concrete Finishes and Protective Coatings for Concrete Surfaces

(a) The paint specialist shall propose painting specifications specific

to the material and against the environmental condition that the material will be subjected to. A warranty period of at least 05 years for the proposed painting and protective coating shall be provided by the paint specialist and manufacturer to the Employer.

(b) The Contractor may design and construct the Electrical and

Control Room with the adjoining Store Room with concrete and masonry. The table below indicates the finishes for the Electrical and Control Room where a protective coating or decorative finish is required.


6.2.1 - 10

Structure Exposed External

Wall Finish

Internal Wall Faces

Top of Slab Underside of Soffit or

ceiling

Top of Roof Slab

Electrical and Control Room; Store Room

Block wall plastered and painted to the approved painting system proposed by paint specialist.

Block wall plastered and painted to the approved painting system proposed by paint specialist.

U1 concrete finish with hardener and dust-proofer for floor.

F3 Finish. No protective coating to underside of roof slab.

Cement screed to fall.

*Note: Requirements for U1 concrete finishes are described in detail under Section 6.3.3.2.5.23; and F3 formwork finishes are described in detail under Section 6.3.3.2.10.5.

(c) Protective coating for floating platform deck, if proposed to be constructed from concrete shall be brushed and anti-slip finished.

(d) For the chemical and fuel bund areas as shown in drawings, the

paint specialist shall propose an appropriate painting or coating protection system for the concrete deck and the bund walls against corrosion from the respective types of chemical or fuel that the bund is designed to contain. If metal lining is proposed to protect the deck and the bund walls against corrosion from the chemical or fuel, the Contractor shall verify to the S.O. that the proposed type of lining will be inert to the chemical or fuel that the bund is designed to contain and that the thickness of the lining is sufficient against any mechanical damage or tear. Road lanes and markings on the floating platform deck shall be applied with thermoplastic paint on top of the proposed coating system for the deck; the colour of the road lane shall be standard white otherwise shall be a contrasting colour with the finished deck. Specification for all proposed painting, protection system or lining shall come with test certifications by SAC-SINGLAS approved laboratory to show the effectiveness of the protection system against corrosion. Accessible areas around the bunds shall ensure that the floor remain anti-slip after painting, coating, lining is applied otherwise provide alternative design for access within the bund.

(e) All costs to design, testing, supply and application for the

proposed painting, protection system or lining shall be deemed to be included in the Contract Sum and shall not subject to an additional payment to the Contractor.


6.2.1 - 11

6.2.1.5 Paint Finishes and Protective Coatings for Structural Steelwork

Surfaces (a) Protective and decorative finishes to structural steel works on the

floating platform shall be proposed by paint specialists such that the service life of the applied coatings system is optimised to the operation requirements of the wastewater treatment plant and the floating platform subjected to harsh marine environment. The painting and protective coating specification as indicated in this Section is for reference. The paint specialist shall propose painting specifications specific to the material and against the environmental condition that the material will be subjected to. A warranty period of at least 05 years for the proposed painting and protective coating shall be provided by the paint specialist and manufacturer to the S.O.

(b) All structural steel not submerged below water shall be factory

blast cleaned and blast primed to System 18 as summarised under Table 6.1.12.4 of the General Specification 6.1.12 and comply to the painting specification proposed by the paint specialist. Final colour coat shall be decided by the S.O.

(c) For the floating platform deck, if it is proposed to be constructed

from steel plates, these shall be applied with non-skid epoxy coating systems that will be durable when applied to the surface preparation. The proposed coating system for the deck shall have adequate skid-resistance properties for vehicular movements. If required, damaged deck plating and fittings shall be descaled and touched up or coated as necessary based on the approved painting specification by the paint specialist. For the chemical and fuel bund areas, the paint specialist shall propose an appropriate painting or coating protection system for the steel deck and the bund walls against corrosion from the respective types of chemical or fuel that the bund is designed to contain.

(d) Road lanes and markings on the floating platform deck shall be

applied using thermoplastic paint on top of the proposed coating system for the deck; the colour of the road lane shall be standard white otherwise shall be a contrasting colour with the finished deck.

(e) Specification for the proposed painting and protection system shall

come with test certifications by SAC-SINGLAS approved laboratory to show the effectiveness of the protection system against corrosion. All costs associated with the design, testing, supply and application for the proposed painting, protection system or lining shall be deemed to be included in the Contract Sum and shall not subject to an additional payment to the Contractor.


6.2.1 - 12

6.2.1.6 Schedule of Doors and Windows

(a) Provision of doors and windows shall be as follows complete with all necessary fixtures and accessories such as door closers, locks and etc.:

No. Location Window External Door

1 Electrical and Control Room ; Store Room

Aluminium fixed window frame

Aluminium solid door completed with powder coated finishes. Colour to be approved by S.O.

(b) Contractor shall design and propose the doors and windows

including its fixtures and accessories to S.O.’s approval. (c) Except for the doors, the Contractor shall provide and install all

windows, vents and any openings at the Electrical Control Room and Store Room with insect screens or nettings with nominal mesh size not larger than 2mmx2mm. The insect screen shall be of high density polyethylene, UV stabilised, chemical and rot resistant. The Contractor shall detail the mounting details for the insect screen with the proposed openings for S.O.’s approval before installation.

6.2.1.7 Access Bridge and Vehicular Access on Floating Platform

(a) The access bridge for vehicular access shall be adequate to allow for weight and movement of a 10-tonne (unladen weight plus load) rigid vehicle with a wheelbase not more than 5 metre long (not articulated) to all access points without having to leave the roadway surface.

(b) The Contractor may propose the most feasible and economical

design for the structure(s) to support the access bridge for vehicular access between the floating platform and the perimeter bund. The Contractor’s QP design shall include all necessary checks including the slope stability of the existing perimeter bund and obtain the approval from BCA and the project consultant accountable for the existing perimeter bund. Structures that are proposed to be constructed on the perimeter bund must not exceed the allowable surcharge load on the perimeter bund. Structures and substructures that provide vehicular access from the existing perimeter bund to the floating platform must be designed to take 10 tonne rigid vehicle load (see also Pipe Trenches in this Specification), or construction loads at least 20kN/m

2 whichever is more critical. All fees associated with

statutory submissions shall be allowed for in the Contract Sum.


6.2.1 - 13

(c) The access bridge linking the floating platform and the perimeter bund shall be designed with a hinge to allow for necessary rotation and movements due to the change in water levels within the Phase II Cell. The Contractor shall take into consideration that during the construction stage, the water level will fluctuate in accordance to the high and low tide levels. The existing seaward entrance into the Phase II Cell through the gap in the bund shall be closed by others as part of a separate Contract. Once the seaward entrance is closed the, water level may be at its lowest before the trapped water in the Phase II Cell side is allowed to rise between 1.5m to 2.5m CD. The Contractor shall make provision in their design for situation of abnormally intense rain storm condition, so that the access bridge may rotate and translate with no damage to the access bridge structure and the services (eg. discharge pipe) mounted on the bridge. The design of the access bridge shall also allow some lateral movements due to possible horizontal movement of the floating platform.

(d) The support system for the access bridge shall be designed by the Contractor’s QP, including all necessary ground investigation to verify that the allowable bearing capacity of the existing perimeter bund is adequate to accommodate all design (including dead and imposed) loadings from the proposed bridge.

(e) The Works shall be carried out in accordance with Singapore

Codes of practices, Standards, Regulations and Statutory requirements.

(f) Vehicular access lane with marking shall be provided on the

floating platform deck level and the width of the lane shall not be smaller than 4.5m. Speed limit (15kph) and vehicle max laden weight signages shall be mounted at the height barrier structure located at the entrance of the access bridge to WWTP and selected areas within the WWTP premises. Painting and coating system for lane marking to be applied on the floating platform deck shall be proposed by paint specialist in accordance to this Specification and the Specification for Painting and Protective Coating under 6.1.12. The lane shall not have any form of fixtures that may obstruct vehicular movements.

(g) The Contractor shall provide and construct road barriers (including vehicle impact guardrails and bollards) to the requirements of LTA standards drawing Nos. LTA/RD/SD99/VIG/1A and 2A, LTA/RD/SD99/BOL/2A. Vehicular impact guardrail shall be provided along both sides of the access bridge. In additional, vehicle impact guardrails shall also be provided along the periphery of the floating platform adjacent to vehicular access lane on the floating platform and these guardrails shall be modified from the LTA standard drawings with two numbers of rails such that the top rails is at least 1.100m high from the deck level. In other areas, the side of the vehicular access lane shall be lined with bollards spaced not more than 3.0m apart and around the


6.2.1 - 14

corners of structural columns that are exposed to vehicle impact. Bollards on the floating platform shall be designed to be removable type and the exterior of the bollards covered by fluorescent yellow micro-prismatic retro-reflective sheeting with black arrows. The Contractor’s QP shall design the road barriers including the connections to the ground or deck in compliance to BS 6399-1 for a minimum design speed limit of 60kph and withstand a vehicle mass of 10tonnes.

(h) Pipe racks or pipe-bridges maybe required within the treatment area at vehicular access lane crossings. Where pipe racks or pipe-bridges are necessary they shall be designed to have a minimum clear height above the road of 4.0m. In addition to protect the pipe rack from accidental damage from tall vehicles, the Contractor’s QP shall propose and design a 4.0m (clear) height restriction barrier erected along the vehicular access lane before any vehicle crosses below the pipe rack. The barrier shall be erected away from the pipe rack by at least 5.0m along the centreline of the vehicular access lane.

6.2.1.8 Access Platform Access platform shall be provided to all structures, pipework valve,

flowmeter, doors and any other access points. If the access points to all structures, pipework valve, flowmeter, doors and any other access points is obstructed by supported pipelines (or the access point is elevated) by more than 0.5m above the floating platform deck level, an access platform with staircase shall be provided. If the access platform is elevated by more than 600mm, safety handrails shall be provided on both sides of the access platform. The surfaces of the access and the access platforms, including staircases shall be non-skid. The Contractor shall propose and submit an access plan around the WWTP with details of the location of steps and demonstrate sufficient maintenance access to the S.O. for approval.

6.2.1.9 Surface Drainage (Platform Deck)

(a) The Contractor shall design and construct the deck of the floating platform such that water does not accumulate and allow for draining of any rainwater back into the Phase II Cell or the Sea. The Contractor shall in their design, anticipate accidental spillage and washing during the re-filling of the chemicals and fuels. All containment bunds, chemical and fuel loading bays shall contain a sump.

(b) Drainage designs and works outside the floating platform,

including drainage for proposed temporary structures, shall be executed in accordance with the Standard Specification for Drainage Works of the Drainage Department, Public Utilities Board Singapore.


6.2.1 - 15

6.2.1.10 Setting Out Of Works

(a) The Contractor shall in their plan, set out buildings and structures with a structure grid system. The structure grids shall be referenced to the Survey 21 System.

(b) Unless otherwise further advised by the S.O., the setting out point

for the junction between the centreline of the proposed access road to the wastewater treatment plant and the South eastern side of the existing perimeter bund crest shall be N19397.422, E21311.659.

(c) Unless otherwise further advised by the S.O., the setting out point

for the junction between the centreline of the proposed Platform structure for LIT (Phase II Cell side) and the South eastern side of the existing perimeter bund crest shall be N19459.338, E21375.160.

(d) Unless otherwise further advised by the S.O., the setting out point

for the junction between the centreline of the proposed Platform structure for LIT (Sea side) and the South eastern side of the existing perimeter bund crest shall be N19445.490, E21388.316.

(e) The Contractor shall engage their Registered Surveyor to conduct

all topographical and hydrographical surveys necessary for their design and site works. Survey plans endorsed by registered surveyor shall be submitted to the S.O. for their records.

(f) The Contractor shall confirm all relevant setting out points on site

with the S.O. prior to commencing work.

6.2.1.11 Earthworks 6.2.1.11.1 Backfilling Works and Shoring System for Excavations

(a) The Works may require excavations to be carried out for the laying pipeline(s) and its ancillary structures. In advance of undertaking any such excavation in excess of 1.5 metres depth the Contractor shall submit a detailed method statement to the S.O. for approval to indicate the proposed method for supporting the excavation. The detailed method statement shall include Drawings and calculations certified by his QP.

(b) For excavations in excess of 1.5 metres in depth the Contractor is

required to comply with statutory regulations for monitoring the stability of the excavation and temporary works and provide the S.O. with weekly field data and monthly reports.


6.2.1 - 16

(c) The Contractor may consider extending the existing sloped bund on the Phase II Cell side to shorten the span of the proposed access bridge between the floating platform and the bund. If backfilling is required to form a new slope over the existing shore slope, the Contractor's attention is drawn to the existing geo-membrane and geo-fabric at the bund which should remain undamaged by the Contractor’s proposed works. The Contractor’s QP or QP (Geotechnical) shall also note that there is also a layer of clay that has been built up on the top surface of the bund. The Contractor’s QP shall propose a detailed method statement, including drawings and calculations certified by the QP, and submit to the S.O. and project consultant for the bund wall for comments and approval. All necessary earthworks, including supply of equipments, machineries, supply and install of backfill materials and geo-textiles, the construction of the embankment extension from the perimeter bund shall be deemed to be included in the Contract Sum. The Contractor shall submit detail plans, calculations and method statement endorsed by the Contractor’s QP or QP (Geotechnical) for S.O. and the project consultant for the existing Bund for approval.

(d) The Contractor is required to carry out a precondition survey in the

vicinity of the proposed work and submit a report to the S.O.. (e) In addition to the monitoring of any existing defects, the

Contractor’s QP shall propose and submit a plan to monitor the stability of the existing shore slope and the stability of the proposed bund extension to the proposed access bridge. It shall be the Contractor’s QP’s responsibility to supervise all the earthworks and ensure the integrity and stability of the existing perimeter bund including the existing shore slope or bund during excavation or backfilling work.

(f) The Contractor shall allow for in his pricing, the professional

service for design, submissions and supervision of the earthworks, including all necessary monitoring instrumentation as required by the Contractor’s QP. The QP may include services from the QP (Geotechnical) as and when required by the Building Control Act and Regulations.

6.2.1.11.2 General Clearance

(a) The depth of top surface earth or rocks at the perimeter bund, proposed to be stripped shall be estimated and be a minimum of 150mm. The Contractor shall verify the actual depth of topsoil by further investigation and shall agree the actual depth to be stripped with the S.O. All stripped earth or rocks should be stored on the site and reused as directed by the S.O.

(b) Ground services are not expected around the proposed site or

bund connecting to the wastewater treatment plant. However it is


6.2.1 - 17

the Contractor’s responsibility to conduct their site investigation to satisfy themselves that their work will not affect any existing ground services or any structures or substructures. The Contractor shall inform the S.O.’s any structures or buried services they locate during their investigation.

(c) The Contractor shall propose design platform levels for the backfill

slopes and any structures to be erected and submit their drawings to the S.O. for comments. The Contractor shall clear and grade the area, taking into consideration the stability of existing shore slopes, new formation of the proposed slope after backfill and the erosion control measures as stipulated in this specification.

(d) The Contractor shall clear the areas indicated on the drawings for

site storage and site offices. The Contractor shall clear all areas necessary for the proposed Works and locate within the proposed works fence line. The Contractor shall cut the weeds and re-grown shrubs to the cleared areas every month throughout the Contract Period.

(e) The Contractor may clear additional areas within the site boundary

of the works that are required for access, storage or administration only with approval from the S.O. The Contractor shall submit to the S.O. a scale plan with suitable setting out dimensions indicating the extent of their proposed general clearance prior to starting any clearance works.

(f) The Contractor is to ensure that his clearance work does not

disturb any permanent or temporary survey markers or pegs that mark out the site boundary. Should any marker be disturbed then the Contractor will be responsible for engaging a registered surveyor to reinstate the marker at his own cost.

6.2.1.11.3 Protection of Sloped Areas during Construction

The Contractor shall take suitable measures to prevent excessive erosion of the existing perimeter bund. The Contractor shall submit to the S.O. detailed plans and a method statement to show how they intend to protect the slopes during the Works. The Contractor may engage a QP or QP (Geotechnical) and AC (Geotechnical) as required by the Building Control Act and Regulations to endorse on the detailed plans and method statement. The Contractor shall be responsible for reinstating the slope with the same type of earth materials that is affected and/or lost by erosion.


6.2.1 - 18

6.2.1.11.4 Earth Control Measures 6.2.1.11.4.1 Erosion and Silt Control Measures

(a) The Contractor shall be responsible for any erosion, siltation anywhere, which is ascertained to be caused directly or indirectly by his work. The Contractor shall take necessary measures to prevent silt being washed into public drains, waterways, reservoirs and abstraction ponds by implementing an Earth Control Measure (ECM) for the construction site where necessary.

(b) The Contractor shall obtain an approval from the regulatory

authority before the commencement of any earthwork.

(c) The Contractor shall be responsible for preventing silt from being washed into public drains by implementing effective Earth Control Measures (ECM) for the construction site to meet the requirements under the latest Sewerage and Drainage Act Cap 294. (Information on ECM requirements can be found in the Code of Practice on Surface Water Drainage and the website www.pub.gov.sg/ECM). The Contractor shall note that the ECM is for the containment and treatment of silty discharges due to the impact of rainwater. ECM is not meant for the treatment of wastewater due to construction activities (such as slurry from tunnelling, pipe-jacking and bore-piling works) which shall be treated to comply with the requirements under Environmental Pollution Control Act (Chapter 94A).

(d) In his tender submission, the Contractor shall submit his schematic ECM plans of the construction site for the whole duration of the Contract period taking into account the different phases of construction activities. He shall also provide the name of the Qualified Erosion Control Professional (QECP) who will be endorsing the ECM plan after the tender is awarded. These schematic ECM plans shall make the Contractor aware of the ECM requirements and the cost to implement an effective ECM. Notwithstanding the submission of these schematic ECM plans, the Contractor shall deem to have separately priced for the ECM in the Contract sum.

(e) Before construction works commence on site, the Contractor shall

engage a QECP to plan and design the ECM, and he shall install the ECM according to the QECP's design. The ECM plan and design shall be submitted one (1) week after the award of the Contract. During the course of the construction works, the Contractor together with his QECP shall review the ECM proposal regularly to meet the changing needs of the construction activities. The Contractor shall improve the ECM as advised by his QECP. The planning and design of the ECM shall meet the minimum requirements stipulated and in accordance to the Code of Practice on Surface Water Drainage.


6.2.1 - 19

(f) The Contractor shall maintain the ECM for the whole duration of the Contract to ensure that it is effective at all times. Proper records detailing the maintenance works, supported by dated photographs, shall be kept by the Contractor for verification.

(g) The Contractor shall not remove the ECM until all works are

completed and upon the advice of his QECP. (h) The Contractor shall submit the ECM proposal duly endorsed by

his QECP to the regulatory authority or agency relevant for the works for records. The proposed ECM shall consist of the following three parts: (i) Project Particulars

The following information shall be provided under the Project Particulars:

(1) Project description (2) Name and address of site occupier; (3) Site area and Contract period; (4) Location map and site plan.

(ii) Erosion Control Plan(s) and Sediment Control Plan(s)

(i) During construction, the Contractor shall minimize the formation of

bare surfaces under the ECM's Erosion Control Plan. The Plan shall depict graphically the activities, including sequence of work, type and duration for each phase of construction activities to include the following measures to:

(i) Sequence and schedule of the earthworks and demolition

works in stages and progressively with the subsequent construction activities and building works.

(ii) minimise site disturbance by keeping site clearance works to a minimum by retaining as much of the existing vegetation as possible.

(iii) pave up the bare surfaces and all construction access by concrete or milled waste or other suitable materials.

(iv) protect the bare slopes with close-turfing, concrete grouting, canvas or erosion control blanket.

(v) protect the earth stockpiles with canvas or erosion control blanket.

(vi) restore ground cover over disturbed areas, which are or have become bare, as soon as possible.

(j) The Contractor shall put in place the ECM's Sediment Control

Plan, which aims to capture the sediments washed down from the construction sites. Some of these sediment control measures and facilities, which must be in place before the works start, shall include but not limited to the following:


6.2.1 - 20

(i) concrete-lined cut-off drains (minimum C7 precast channel) along the perimeter of the construction sites.

(ii) silt fence properly installed and embedded onto the ground along the perimeter cut-off drains (between the construction site and the cut-off drain).

(iii) sedimentation basins or any other sediment filtering or settling system of adequate size and sufficient numbers along the perimeter cut-off drain and before the discharge points into public drain.

(iv) a treatment system to be provided before the discharge points into public drain. A storage basin / tank may be required to capture the runoff before treatment.

(v) turbidity curtains shall be installed along all the exposed slopes / riverbanks for works in or adjacent to water bodies, such as canals, rivers, sea or in a reclamation work. The silty discharge trapped within the turbidity curtain shall be allowed to be settled or treated.

(k) The QECP shall submit full basis of design back up with design

calculations to show clearly how the perimeter cut-off drains, silt fence, sedimentation basins and storage basin / tank are designed and sized as well as how such design will effectively filter off silt and allow only clean water to discharge into public drains. The QECP shall also submit the design specifications on the treatment system which can effectively treat the silty discharge from the construction site. The intensity of a one-in-two year storm should be adopted for the proposed design.

(l) Not withstanding the above specifications, the following

requirements must be taken into considered by the QECP in the preparation of the Erosion and Sediment Control Plans.

(i) The entire site office area shall be concrete paved. (ii) All temporary access for vehicles and plants i.e. cranes,

excavators etc. must be properly constructed. The access may be formed with well-compacted hardcore blinded with sand and concrete paved or covered with milled waste. Wheel washing facility shall be provided at exits form the worksite and the wash water treated.

(iii) All earth slopes and erodible surfaces adjacent to the worksite shall be concrete lined or covered with erosion control blanket or close turfing.

(iv) During trench excavation, the maximum length of trench opened should not exceed 50m. Any excavated materials stock pile on site must be covered with canvas sheet. If the stock pile has to be left on site for more than 3 days, a silt fence must also be constructed around the stock pile to retain any silty water that may leach out when rain falls. At the end of each work day, both backfilled and open trenches must be covered by canvas sheets firmly pegged to the ground. The backfilled trenches must remain covered until the completion of turfing/ reinstatement work.


6.2.1 - 21

If the earth stock pile is to be left on site for more than three (3) weeks, it shall be covered up with erosion control blankets or close turfing.

(v) At every 50m length of cut-off drain (or part there-of), one standard silt trap shall be provided. The standard silt trap or approved equivalent shall be of size 1m wide x 2m length x 1.5m depth with suitable graded stones and geotextile or equivalent (as shown in Drawing No. 9 of ‘Code of Practice on Surface water Drainage’ and polymer blocks shall be used to aid in the silt settlement before the water is discharged.

(vi) After any rain event, the silty water pumped from the trenches, shafts, sedimentation ponds, within the silt-fenced areas, etc must not discharge into the open drain. Instead it should be stored in portable tanks for treatment by silty water treatment unit or transported to designated water treatment plant for treatment to meet the discharge standard.

(vii) The above requirements are deemed to be included in the items for the implementation and maintenance of Erosion and Sediment Control Plans. The Contractors are advised to price adequately for these items.

6.2.1.11.4.2 Silt Curtains

Silt curtains or turbidity curtains are to be installed on impounded waters on the Phase II Cell side and in specified locations on the seaward side. The silt curtains located within the Phase II Cell shall be permanent or provided on a long term basis around the floating platform such that amount of silt suspended in the impounded water will be reduced when pumped into wastewater treatment plant. Silt curtains installed in the Phase II Cell shall cover the area around the floating platform (or WWTP). The silt curtains shall be at least 25m away from the submersible pumps mounted on floating platform and the bottom edge of the silt curtains extended down to the Phase II Cell-bed. Upon operation for the WWTP, two numbers (primary and secondary) silt curtains shall be provided and adequately spaced apart to QECP, specialist and/or manufacturer’s recommendation. The primary silt curtain must be feasible to be replaced while the secondary silt curtain remains in place to prevent any silt from infiltrating into the waters around the WWTP floating platform when the primary silt curtain is removed and changed The Contractor’s specialist shall design the curtain to be easily changed and minimise the needs for divers to operate in the contaminated waters. The Contractor shall submit a Method Statement on the maintenance and changing of the silt curtains for S.O.’s approval. Silt curtains for the construction of the Platform structure for LIT (Sea side) shall comply the requirements as stated in the ECM plan as design by the QECP highlighted for Erosion and Silt Control Measures in this Specification.


6.2.1 - 22

All silt curtains shall be adequately designed by the QECP and the specialists or manufacturer. (a) Works in General

(i) The works including the design, fabrication, and installation of the primary and secondary turbidity curtains shall ensure that the turbidity of water in the water bodies around the works shall not exceed the pre-existing levels or 50mg/l whichever is greater.

(ii) The works in this Specification consists of all

construction operations relating to the turbidity curtain. These construction operations include, but are not necessarily limited to the following:

(1) Design, manufacture, install and maintain primary

and secondary turbidity curtain(s) around the areas of marine construction, either across the water body to enclose the entire work area, or individual curtains within /around /along the water body to enclose work areas.

(2) Curtain(s) shall remain in place during excavation, installation of piles, foundations etc and backfilling works. The Contractor shall maintain the curtain(s) in good working condition for the duration of construction works. The turbidity curtain(s) shall not be removed until all operations have been completed and the water quality within the confines of the turbidity curtain meets the prescribed standards. The contractor shall install as many turbidity curtains as are necessary to meet the water quality standards.

(3) The primary and secondary curtain(s) shall be

installed to meet the requirements of these specifications.

(iii) The purpose of the curtain is to minimise the transport of

turbidity and other constituents generated by construction activities in the water body.

(iv) The turbidity curtain system shall provide sufficient

residence time to allow soil particles to fall out of suspension, reduce turbidity and meet the water quality standards.

(v) The Contractor shall install secondary curtain(s) and take

turbidity measurements at specified distances from the edge of each outermost installed curtain.


6.2.1 - 23

(vi) The Contractor shall develop a plan to monitor the turbidity

through the water column at three distances from the edge of each outermost installed turbidity curtain. Make initial measurements at a distance of 30m, 60m and 100m from the edge of the primary curtain with turbidity measured at four depths in the water column, then adjust distance and depth as appropriate based on the direction of the plume, plume velocity and the change in turbidity with distance from the work area. Initial measurement shall be made three times a week.

(vii) The Contractor QECP shall have the approved design of

the secondary curtain(s) available before earthworks commence and/or after the floating platform is positioned in Semakau Landfill. Each area shall be surrounded by a primary and secondary curtains adequately spaced apart. Such requirements shall be met before construction activities begin.

(b) Curtain Fabric

(i) Primary and Secondary Turbidity Curtain: The curtain shall be a combination of permeable or impermeable materials. The curtain heavy weight, flexible, nylon-reinforced, polypropylene filter fabric, or flexible nylon reinforced thermoplastic as necessary to control turbidity created during construction, sewn into panels, hemmed and edges finished to prevent ravelling.

(ii) Connectors and Tensioned Load line: the curtain shall be provided with appropriate galvanised steel snap hooks and rings for connecting load lines.

(iii) Flotation: The Contractor shall provide a sufficient number

of expanded polystyrene floats or equivalent, sufficient to keep the top of the curtain above the water surface with a minimum of 150mm of freeboard at all times or at least half of the floats to be above water at all times, whichever is the larger.

(iv) Ballast and anchorage: Each curtain shall be equipped

with a galvanised steel chain integrated into the bottom of the fabric to keep the curtain vertical and in contact with bottom of the waterbody. Each curtain shall also be anchored to the water bed to prevent excessive displacement from wind, waves and currents. The ballast, anchorage and floatation shall be designed by the curtain manufacturer for the wind and wave conditions, bottom profile and changes in water level. Anchors shall be spaced as necessary to secure each curtain and keep it stable in all conditions. Anchorage and/or floatation shall


6.2.1 - 24

be designed to keep the top of each curtain above the water surface when subjected to wind or wave forces. The Contractor shall also design, provide and install shore anchoring where each curtain is attached to the shoreline. The Contractor shall also design, provide and install marine anchorage as necessary to secure each curtain.

(v) Load Line: The Contractor shall fit the curtain(s) with

galvanised wire rope with vinyl coating of sufficient strength to resist all internal and external loadings.

(c) Execution

(i) Pre-installation profile: Prior to manufacturing the

curtain(s), the Contractor shall develop a profile of the water body bed for each curtain location through his survey. The curtain manufacturer shall use this information to dimension the curtain(s) with allowances for water level changes.

(ii) Curtain design: The curtain systems shall consist of a primary impermeable or permeable curtain, plus secondary curtain(s) as necessary to meet water quality standards required by the approving authority or agency. Each primary curtain shall have an impervious or permeable section of sufficient depth. The Contractor shall have his specialist or supplier to design each curtain to suit the environment that the silt curtains will be subjected in. The curtain system design shall consider all parameters related to temperature, wind, wave and current conditions at the project site as well as the anticipated varying water levels.

(iii) Curtain fabrication: Each curtain shall be manufactured or

supplied by a specialty subcontractor with experience in turbidity curtain design and fabrication. Project references from the Contractor’s specialty subcontractor for turbidity curtain will be required to be submitted to the S.O. for his reference. The curtain as designed shall be able to accommodate expected water level variations. If necessary, each curtain shall be provided with additional longitudinal panels that can be added when the water level rises and with removable panels that can be pulled out when the water levels drops. The design should make provision for movement of equipment or material though the curtains as may be required for operation.

(iv) Primary curtain installation: The exact locations shall

provide sufficient working space compatible with the construction methods and also within the work limits of the contract. The primary curtain shall be installed before the commencement of any works in and around the water. The deployment of the curtains shall be in conformance with


6.2.1 - 25

the manufacturer’s recommendations which shall be submitted to the S.O.

(v) Secondary curtain installation: the secondary curtain shall

be adequately spaced from the primary curtain. Before the suction pumps of the wastewater treatment plant first operates (including the period when the wastewater treatment plant is to be tested and commissioned), the Contractor shall deployed the secondary curtain for the floating platform with the primary silt curtain. Replacement curtains shall be installed within 2 days from the day the turbidity exceeds the water quality standard.

(vi) Maintenance: The Contractor shall maintain, repair and

adjust the curtains as necessary throughout all construction activities. The Contractor shall visually inspect the turbidity curtain(s) at least weekly. A written copy of the inspection report shall be submitted to the S.O. and the Contractor’s QECP for reference.

(vii) Curtain removal: At the completion of all construction

activities, the Contractor shall remove all turbidity curtains in their entirety. This includes all anchoring devices. The curtain should not be removed until the water inside the enclosed area meets the water quality standards.

(d) General properties for silt curtains

(i) The Contractor’s QECP shall recommend to the S.O. the

most appropriate and economical design and type of turbidity curtains for the project during construction. The curtain to be used on a long-term basis around the floating platform shall have the following or equivalent properties, if not better.

No Properties Test Method

1 Mass per unit ISO 9864:2005 > 600 g/m2

2 Thickness ASTM D5199 > 1.1mm

3 Mean wide width tensile strength

ASTM D4595 > 200kN/m

4 Mean tensile extension at Max load

ASTM D4595 15%

5 Elongation at Break ASTM D4595:1986

<20%

6 Water permittivity ASTM D4491:1999

> 0.8 per sec

7 Shrinkage under seawater

ISO 7771:1985 0.2%

8 Seawater permeability ASTM D4491:1999

> 1.4 x 10-3

cm/sec


6.2.1 - 26

No Properties Test Method

9 Tensile strength retention after 90 days exposure to sunlight in Singapore UV resistance

ASTM D4595 > 80%

(ii) Floating booms shall be bright orange or yellow colour that

will attract the attention of boaters in the vicinity. Floatation material must be solid float type. Hollow core floats, including pipes and tubes are not allowed.

(iii) The Contractor shall submit the accredited test report of

local approved laboratories, technical calculations (after the Contractor’s QECP has reviewed without further comments) and project references with local applications to the S.O. for his approval.

6.2.1.11.5 Temporary Stockpile and Disposal of Materials off Site (a) The Contractor shall confine all the works within the site area

allocated to him. No additional area will be allocated for the Contractor’s as temporary work area/site storage. The Contractor shall plan to stockpile excavated material prior to backfilling at this location. The stockpile height shall not exceed 5m and the sides of the stockpile shall be stable. The Contractor shall submit plans for the approval of the S.O. indicating the proposed layout of the stockpile, how access will be achieved and the slope of the stockpile sides. The Contractor shall also submit calculations proving the stability of the stockpile for a variety of slip plane scenarios and different moisture contents.

(b) Surplus earth and demolition material shall be disposed off site to

a registered disposal point approved by the relevant authority and S.O. The Contractor shall ensure that a log of all materials disposed off site is kept and a copy given weekly to the S.O. The S.O. may request for the volume of surplus material and loads to be confirmed by weighing. These checks will not be carried out unreasonably and it is not the intention to check every load unless there is deemed to be sufficient doubt in the accuracy of the logs. All of the Contractor's costs associated with a check requested by the S.O. on the weight of a load shall be deemed to be included in the Contract Sum and shall not be subject to an additional payment to the Contractor.

(c) As the work area at Semakau Landfill is offshore and constrained

in space, the Contractor may be required to plan for any temporary work/site storage areas on the Singapore mainland. It is the Contractor’s responsibility to plan and coordinate these location(s) including the construction of the floating platform and the associated wastewater treatment plant. The Contractor shall


6.2.1 - 27

inform the S.O. and his agents the locations of all of the temporary sites outside the assigned work site at Semakau Landfill. The Contractor shall coordinate and provide transport and accessibility to the S.O. and his agents to inspect the work progress at all the temporary work sites upon S.O.’s request. The Contractor shall price in all necessary costs in logistics and the location(s) for construction. All the Contractor’s costs associated in the temporary work/site storage, construction yards, transportation and logistics costs shall be deemed to be included in the Contract Sum and shall not subject to an additional payment to the Contractor.

6.2.1.11.6 Backfilling around Structures

(a) The Contractor shall take particular care during construction to ensure that all foundations of any structural elements, especially the foundation support for the access bridge, are adequately founded.

(b) Engineering fill shall be used at all locations where components of

structures are subsequently to be founded on backfilled or filled areas. Backfilling shall be carried out in 300mm layers and thoroughly compacted with a mechanical compactor to the satisfaction of the S.O.

6.2.1.11.7 Foundations for Structures

(a) The Contractor shall design the foundation for any structures that he deemed is necessary for the project and shall price in all necessary costs to design, supply and construct the proposed foundation and structure. The Contractor shall note that impact to the existing bund in particular to the geo-membrane and geo-fabric already laid along the shore slope, shall remain intact and shall not be damaged by the proposed works.

(b) The proposed foundation system for structures generally shall comprise of pad type footings or raft footings. The Contractor shall conduct their ground investigation and verify the allowable bearing capacity at the proposed formation level by means of plate bearing tests. The Contractor’s QP shall determine the extent and the type of soil investigation eg. plate bearing tests or boring works, are required to appreciate the soil properties of the existing ground, including the sea-bed, that he may require to verify his foundation design.


6.2.1 - 28

6.2.1.12 Concrete Works 6.2.1.12.1 Prevention of Flotation

(a) The Contractor is warned that underground structures such as buried chambers may not be heavy enough to resist uplift due to water pressure. The Contractor shall make adequate arrangements to keep excavations dry or adopt other approved means of ensuring the stability of the Temporary or Permanent Works until they are completed.

(b) The Contractor should note the ground water conditions observed

during the period of the ground investigation. (c) Submerged pipes may be subjected to floatation. The Contractor

shall, in their design, provide anchor concrete blocks with stainless steel saddle to hold the pipe in place.

6.2.1.12.2 Concrete Anchor Blocks

Concrete blocks may be proposed by Contractor to counterweight the effects of floatation. The concrete block shall be designed by the Contractor’s QP and have sufficient concrete cover to maintain the integrity of the reinforcement within the concrete. Such concrete blocks shall be precast and have achieved the required 28 days design strength prior to installation. The Contractor shall provide a method statement for the installation of the concrete blocks, including the Contractor’s QP calculations for the structural capacity of the block and the allowable bearing capacity for the sea-bed or soil. The Contractor shall price in all necessary costs to design, supply, construct and install the concrete blocks.

6.2.1.12.3 Standards Compliance

All civil and structural computations shall be in full compliance with all relevant standards and codes of practice, which shall include the following requirements besides the reference standards listed in Section 6.3:

6.2.1.12.3.1 Loads and Structural Design

CP 3 : Chapter V : Part 2 Code of Basic Data for the Design of Buildings Loading – Wind Loads

BS 6399-1 Loading for buildings. Code of Practice for dead and imposed loads

BS 6399-2 Loading for buildings. Code of Practice for wind loads

BS 6399-3 Loading for buildings. Code of


6.2.1 - 29

Practice for imposed roof loads

BS 4592 Industrial type flooring and stair treads

BS 2573-1 Rules for the design of cranes. Specification for classification, stress calculations and design criteria for structures

Land Transport Authority (LTA)’s design criteria for vehicular bridge

(Vehicular bridge live loads)

BS 648 Schedule of weights of building materials

SS CP 65:Part 1 Structural use of concrete – Design and Construction

SS CP 65:Part 2 Structural use of concrete – Special Circumstances

SS CP 73 Code of Practice for design of concrete structures for retaining aqueous liquids

Design Guide of High Strength Concrete to Singapore Standard CP65 - BC2

(Reinforced and Prestressed Concrete Structures)

BS 8110-1 (See Note below)

Structural use of concrete. Code of practice for design and construction


Structural use of concrete. Code of practice for special circumstances


Structural use of concrete. Design charts for singly reinforced beams, doubly reinforced beams and rectangular columns

BS 5950 Part 1 Structural use of steelwork in building – Code of practice in simple and continuous construction: hot rolled sections

Design Guide on Use of Alternative Structural Steel Materials to BS5950 and Eurocode 3 – BC1

(Steel Structures)

BS 5950-1 Structural use of steelwork in building. Code of practice for design. Rolled and welded sections


6.2.1 - 30

BS 5950-2 Structural use of steelwork in building. Specification for materials, fabrication and erection. Rolled and welded sections

BS 5950-3.1 Structural use of steelwork in building. Design in composite construction. Code of practice for design of simple and continuous composite beams

BS 5950-4 Structural use of steelwork in building. Code of practice for design of composite slabs with profiled steel sheeting

BS 5950-5

Structural use of steelwork in building. Code of practice for design of cold formed thin gauge sections


Specification for the use of structural steel in building. Metric units

SS CP 4 Code of practice for foundations

BS 8118 Structural use of Aluminium

BS 8002 Code of Practice for earth retaining structures.

BS 5400 Steel, Concrete and Composite Bridges

BS 2853 Specification for the design and testing of steel overhead runway beams.

BS 5395-3 Code of Practice for the design of industrial type stairs, permanent ladders and walkways

BS 6349-1-1 Maritime structures-Part 1: Code of practice for general criteria

BS 6349-1-2

Maritime structures-Part 1-2: Code of assessment of actions

BS 6349-1-3 Maritime structures-Part 1-3: Code of practice for geotechnical design

BS 6349-1-4

Maritime structures-Part 1-4: Code of practice for materials

BS 6349-2

Maritime structures-Part 2: Code of practice for design of quay walls, jetties, and dolphins


6.2.1 - 31

BS 6349-4

Maritime structures-Part 4: Code of practice for design of fendering and mooring systems

BS 6349-5

Maritime structures-Part 5: Code of practice for dredging and land reclamation

BS 6349-6

Maritime structures-Part 6: Design of inshore moorings and floating structures

BS 6349-7

Maritime structures-Part 7: Guide to the design and construction of breakwaters

BS 6349-8 Code of practice for the design of Ro-Ro ramps, linkspans and walkways

Note for above table: The local design code, otherwise the current (latest) version of the design code, shall be adopted for design unless there is/are valid reason(s) that the local and current design code is insufficient or has no relevant provisions for the engineering design.

6.2.1.12.3.2 Construction Materials

Construction materials shall comply with the following standards: Type of materials Singapore or British design

standards

(a) Cement (i) Ordinary Portland cement – SS 26; (ii) Specification for sulphate resisting Portland cement – BS 4027; (iii) Supersulfated cement – BS 4248; (iv) Portland blastfurnace cement – SS 477; and (v) High slag blastfurnace cement – SS 476.

(b) Ground granulated blast furnace slag

Specification for ground granulated blastfurnace slag for use with Portland cement - BS 6699.

(c) Aggregates Aggregates from natural sources for concrete – SS 31.

(d) Water Methods of test for water for making concrete – BS3148.

(e) Steel reinforcement

(i) Steel for the reinforcement of concrete – SS 2;


6.2.1 - 32

(ii) Cold-reduced steel wire for the reinforcement of concrete and the manufacture of welded fabric – SS 18; and (iii) Welded steel fabric for the reinforcement of concrete – SS 32.

(f) Prestressing wires, strands or bars

(i) Specification for high tensile steel wire and strand for the prestressing of concrete – BS 5896; and (ii) Specification for hot rolled and processed high tensile alloy steel bars for the prestressing of concrete – BS 4486.

(g) Concrete (i) Concrete – Guide to specifying concrete & methods for specifying concrete mixes – SS 289; and (ii) Control on alkali content in accordance with BRE Digest 330 ‘Alkali-silica reaction in concrete’ (2004) by- using low alkali cement1 with equivalent Na2O of not more than 0.6% ; or limiting the total alkali content of concrete to 2.5kg equivalent Na2O/m3.

(h) Admixture Concrete admixtures – SS 320.

(i) Structural steel (i) Specification for weldable structural steels. Hot finished structural hollow sections in weather resistant steels – BS7668; (ii) Hot rolled products of structural steels – BS EN 10025; (iii) Hot finished structural hollow sections of non-alloy and fine grain steels – BS EN 10210; (iv) Cold formed welded structural hollow sections of nonalloy and fine grain steels – BS EN 10219; (v) Stainless steels - BS EN 10088; and (vi) Design Guide on Use of Alternative Structural Steel Materials to BS 5950 and Eurocode 3 – BC1.

(j) Aluminium and aluminium alloys

(i) Sheet, strip and plate – BS EN 485; (ii) Wrought products: Temper designations – BS EN 515; (iii) Chemical composition and form of


6.2.1 - 33

wrought product – BS EN 573; (iv) Extruded rod/bar, tube and profiles – BS EN 755; and (v) Extruded precision profiles in alloys EN AW-6060 and EN AW-6063 – BS EN 12020.

(k) Fixings of claddings Mechanical properties of corrosion-resistant stainless steel fasteners – BS EN ISO 3506.

Unless there is a change in the local building regulations whereby the above code of practices and relevant standards may be superseded, the civil and structural computations shall be in full compliance with the new relevant standards and codes of practice as determined by the Building & Construction Authority (BCA), Building Control Act and Regulations. There shall be no cost and time implications claimable by the Contractor against the Employer for such a change in regulations and shall be considered as priced in the Contract by the Contractor. Structural design standards based on the Eurocodes will coexist with the Singapore/British design standards before full implementation on 1 April 2015. During this co-existence period, either the current Singapore/British design standards or the Eurocodes are acceptable standards by BCA. However, inappropriate mixing the new Eurocode design standards with the current Singapore/British design standards within the same building design will not be acceptable.

6.2.1.12.4 Design Criteria The Contractor’s QP shall consider the following parameters in his design: (a) Exposure conditions and fire rating

(i) Exposure Condition

Concrete for structures on floating platform: Concrete for structures below high tide level:

Very Severe (Table 3.2 of CP 65) Most Severe

(ii) Ambient air temperature : 23.70C – 30.7

0C

(iii) Water temperature range : 260C – 32

0C

(iv) Fire : 2 hour

(b) Concrete cover

Concrete cover to reinforcement (including links) to meet durability requirement shall be as follow: (i) Substructures (earth-surfaced) : 40mm (ii) Substructures(face cast against blinding) : 50mm


6.2.1 - 34

(iii) Water retaining Chamber (liquid face) : 40mm (iv) Superstructures : 40mm (v) Concrete below high tide level : 50mm

6.2.1.12.5 Material Strength

The Contractor’s QP shall consider the following parameters in his design. Should the Contractor’s QP propose to change the parameters, he shall comply the Building Control Act and Regulations and ensure that the design intent include the design class, material standards, steel and concrete grades and testing regimes to comply with the latest version of BC1 and BC2. The design parameters adopted shall be clearly specified on the drawings and submit to the S.O. There shall not be any time and cost implications claimable by the Contractor against the Employer for such changes to proposals.

(a) Concrete Grade

The minimum 28-day compressive cube strength of concrete for the specified structural elements shall be as follows unless specified otherwise:

(i) Concrete blinding for substructures (50mm

thick) : Grade C15

(ii) Concrete blinding for water retaining structures (75mm thick) :

Grade C20

(iii) Mass concrete and benching : Grade C20 (iv) Precast concrete : Grade C50 (v) Reinforced structural concrete in non-water

retaining structures : Grade C40

(vi) Substructures, superstructures, plinth : Grade C40 (vii) Reinforced structural concrete in water

retaining structures : Grade C35A

(viii) Concrete submerged: Grade C50

(b) Steel Reinforcement

(i) Hot-rolled high yield rebars to SS 2 (Type 2) deformed :

460 N/mm2

(ii) Hot-rolled mild steel rebars to SS 2 : 250 N/mm2

(iii) Steel fabric mesh to SS 32 : 485 N/mm2

(c) Structural Steel

(i) Structural steel to BS5950:2000 or

standards as detailed in BC1:2012: 275 N/mm

2


6.2.1 - 35

(d) Marine grade aluminium EN AW 6061

(i) Structural aluminium to BS EN1999-1-1 Table 3.2a & 3.2b EN AW 6061.minimum characteristic 0.2% Proof Stress

240 N/mm2

6.2.1.12.6 Cement

The cement used for the substructures works shall be Portland blast-furnace slag cement. The cement used for all other concrete shall be ordinary Portland cement. In addition, the reinforced structural concrete for water retaining structures shall comply with the clauses below.

6.2.1.12.7 Water Retaining Structures 6.2.1.12.7.1 Cement and Aggregates

(a) The minimum cement content for water retaining structures shall

be 325kg/m3. The maximum cement content shall be not greater than 400kg/m3 if using Ordinary Portland Cement or if using a ground granulated blast furnace slag (GGBS) or pulverised fly ash (PFA) cement this may be increased to not greater than 450kg/m3. For prestressed elements, the cement content may be increased to 500kg/m3 or 550kg/m3 if using a GGBS or PFA mix.

(b) When using a concrete mix, the maximum percentage by mass of

GGBS that shall be used is 50% or if using PFA, the percentage by mass shall be between 15% and 35%.

(c) The nominal size of aggregate shall be 20mm. In any case, the

size of aggregate shall not exceed 25% of minimal thickness of member.

(d) Aggregates shall generally not have an absorption greater than

3%. 6.2.1.12.7.2 Control of Shrinkage

(a) In water retaining structures and elsewhere as directed by the S.O., high workability, low water cement ratio mixes are required. The maximum water cement ratio shall be 0.55 or if using PFA this shall reduce to a maximum of 0.5.

(b) To ensure suitable workability the Contractor may propose a mix

design with an approved plasticising agent. The plasticiser shall be used in strict accordance with the manufacturer's instructions and requirements outlined in specification for Concrete Works.


6.2.1 - 36

(c) The Contractor has a responsibility to ensure that his sequence and method of construction do not compromise the integrity of the permanent works. To this end, the Contractor must ensure that his planned construction bay sizes do not exceed those specified in CP73 for the reinforcement detailed.

(d) The Contractor shall submit a detailed method statement and a

dated sequential programme showing his proposed layout and order of his concrete pours.

6.2.1.12.7.3 Water Testing of Water Retaining Structures

(a) As soon as possible after the completion of each water retaining

structure and on the completion of the internal jointing or surface dressing as the case may be, the Contractor shall remove all dirt, debris materials, tools etc. and shall wash and brush down all internal surfaces to the satisfaction of the S.O.

(b) Water testing of any structure shall only begin after receiving

written approval from the S.O. and the results of the 7 day cube strength test are known for all structural sections.

(c) Each water-retaining structure shall be gradually filled at a uniform

rate not exceeding 1 meter per 12 hours to the normal maximum working level which for the purpose of this clause shall be taken as 75 mm below the overflow unless otherwise directed by the S.O. Each compartment of a multi compartment structure shall be tested independently with adjacent compartments empty, unless instructed otherwise by the S.O. When the structure is first filled it shall be left to stand for seven days to allow the concrete to absorb water and the level maintained by the addition of further liquid. The water level shall then be determined by means approved by the S.O. The structure shall be tested for a period of seven days by daily measurement of water levels. During the seven day test period the total permissible drop in water level, after allowing for evaporation and rainfall where appropriate, shall not exceed 1/500 of the average water depth of the full tank. Any wall drainage or under drainage system shall be monitored during the test period for flow. In the event that leakage is found to be excessive, the Contractor shall at once investigate and determine the point or points of leakage, the water level being lowered in stages if required. Wherever applicable the external surfaces shall be carefully examined for damp patches and other signs of leakage. Notwithstanding the satisfactory completion of the above test, any visible leakage on the outside faces of the structure shall be stopped. Any caulking or making good of cracks in the wall section shall, where practicable be carried out from the inside face. The Contractor shall carry out any remedial work necessary to stop the leak in a manner to be directed by the S.O. Dirt, etc. shall again be removed and refilling and retesting repeated.


6.2.1 - 37

(d) The procedure shall be repeated as many times as may be necessary to achieve water tightness, and no water retaining structure shall be deemed to have been completed or approved by the S.O. until it shall have been ascertained to be in a watertight and usable condition by the S.O.

(e) Where the surfaces of water retaining structures are to be painted

or receive some other form of surface treatment, these structures shall pass the water tightness test to the satisfaction of the S.O. prior to the application of such coatings.

(f) The Contractor shall make all arrangements necessary for

conveying the water from the source to the point of filling, for transferring and for its eventual disposal. All such arrangements shall be subject to the approval of the S.O. The Contractor shall provide all hoses, pumps and other equipment necessary to carry out the tests.

(g) The Contractor shall supply water to carry out the water tightness

test of structures.

(h) The water used to test the first unit of the structure to be tested shall be reused for the subsequent tests of other units of the same structure and should be also used for other structures where practicable.

6.2.1.12.7.4 Structures to be Tested

Any proposed liquid retaining structures shall be tested in accordance with the requirements of the Clause above.

6.2.1.12.8 Joints in Concrete

The Contractor shall in his proposed drawing, indicate the required movement joints if any. The Contractor shall submit details of all movement joints and including waterproofing details, as necessary, for the approval of the S.O. No movement joints shall be used unless approved by the S.O. Construction joints shall be used in locations as approved by the S.O. in accordance with the Contractor's approved method statement. All joints shall conform in every respect with the details shown on the Drawings. All movement joints in a water retaining section of the structure shall be made with a water-stop within the concrete thickness. The Contractor shall submit a method statement for the approval of the S.O. of how high quality compaction of concrete around the water-stop will be achieved and how the water–stop will be prevented from folding out of position during concrete pouring.


6.2.1 - 38

6.2.1.12.9 Casting Walls

Walls with multiple panels shall be cast in alternate panels so that no panel shall be poured abutting to a panel poured less than 7 days previously unless approved by the S.O. Each panel shall be covered with a curing system as detailed in Concrete Works under General Specification 6.3.3.2 and as approved by the S.O.

6.2.1.12.10 Casting Floor

The floor slabs shall be cast in panels in a "Chequer Board" fashion. The time which shall elapse before casting any adjacent panel shall be as approved by the S.O. in accordance with the Contractor's approved method statement but shall not in any case be less than 3 days.

6.2.1.12.11 Imperfections in Internal Concrete Surfaces

Imperfections in internal concrete surfaces that do not comply with the specified finish quality shall be rubbed down with carborundum stone, the resulting grit and dust being thoroughly washed off with clean water. After the rubbing down and as a separate operation, a 1 to 1.5 cement and sand mixture shall be worked into the pores over the whole surface with a fine carborundum flint in such a manner that no more material is left on the concrete face than is necessary completely to fill the pores, so that an extremely smooth and dense surface shall be obtained, to the satisfaction of the S.O.

6.2.1.12.12 Protection of Concrete Floors

No mechanical plant shall be permitted to run on finished floors and the floor area shall not be used without the consent of the S.O. for the storage or stacking of any materials.

6.2.1.12.13 Maximum Permissible Loadings on Roofs and Suspended Slabs

(a) The Contractor shall limit the laden weight of his construction work on the roofs and shall submit to the S.O. for approval. Unapproved works on roofs shall not be permitted to operate under any circumstances unless the Contractor’s QP has specifically design the structure to take such loadings. The Contractor shall not stack soil, free draining material or other construction material on roofs except for the purpose of spreading and levelling the said materials thereon.

(b) The Contractor’s QP shall in his design limit the maximum

permissible imposed uniformly distributed load (UDL) during construction activities, 7.5 kN/m

2 for all concrete suspended floor


6.2.1 - 39

slabs and 1.5 kN/m2 for all

roofs unless the Contractor’s QP decide

otherwise. Detail imposed loadings used in the Contractor’s QP design shall be clearly stated and summarised in the QP’s design report and submit to the S.O. for his reference.

6.2.1.13 Roof Construction

(a) This clause shall be read in conjunction to General Specification 6.3.3.3 for Metal Roofing Works.

(b) During construction of the roof the Contractor shall take particular

care to avoid any stresses or displacement of the tops of the columns due to unequal loading.

(c) The Contractor shall limit the laden weight of his construction work

on the roofs and shall submit to the S.O. for approval details of all works which he proposes to use on the roofs prior to first use. The Contractor shall not stack soil, free draining material or other construction material on the roof in any way, which causes the allowable load limit to be exceeded.

(d) The roof exposed to weather shall be inspected for leakage during

wet days or wet condition. Leakage shall be defined as any surface where water droplets, not caused by condensation, are visible, or any significant discoloration of the concrete caused by damp penetration that remains unimproved 7 days. Any areas of ingress of water shall be investigated and made good to prevent the inflow of water, whether from the rain or from the adjacent water retaining structure.

(e) The Contractor shall engage a roofing specialist to propose

roofing sheet materials, profile and design connections suitable for roofs in a marine coastal environment, with minimal maintenance required over the design lifespan of the wastewater treatment plant. The roofing specialist shall propose roofing sheet with the following properties or better.

(f) On plan, the roof perimeter shall extend at least 1.0m beyond the

bund walls containing the chemical tanks and dosage systems. The roof shall be sloped at least 3-degree away from the main access path adjacent to the bund and the ceiling shall be at least 2.0m clear from the tallest tank or structure.

6.2.1.13.1 Metal Roofing System

(a) The metal roofing system proposed by the Contractor’s Roofing

Specialist, shall provide shelter and all components of the system including the design shall be adequate under severe marine environment.


6.2.1 - 40

(b) The roofing shall have conceal fastening to ensure better durability of the roof in terms of water tightness, especially in marine or industrial areas.

6.2.1.13.2 Metal Roofing

(a) The sheets should be installed with compatible proprietary interlocking clips to lock the male rib. The clips should lock firmly into the underside of the center and female ribs and in turn fastened to support with wafer-head self-drilling zinc coated fasteners. The clips shall be concealed and no fasteners are to penetrate the cladding.

(b) The design steel roof shall be designed to slope adequately to

drain and minimise any possibility of water to stagnate at the roof. The roofing sheet proposed shall be suitable for the design slope of the roof with or without end-laps.

(c) Galvanised steel zed-subgirt shall be provided at along every

purlin’s spacing, recommended spacing of 1200mm C/C. Minimum thickness of galvanised steel zed-subgirt shall be 1.0mm.

(d) The profile and clips shall be tested in accordance with AS 1562.1

– 1992 Design and Installation of Sheet Roof and Wall Cladding – Metal, and AS 4040.2 -1992 Resistance to Wind Pressure for Non-cyclonic Regions.

6.2.1.13.3 Finishes

(a) General

The steel sheet shall be resistance to dirt staining coating and is able to give a combined long-term durability and corrosion resistance. Its substrate/ metallic coating conform to Australian Standard AS1397 and SS370:1994 whilst its paint coating conforms to AS/NZS 2728.

(b) Protective Metallic Coating/ corrosion resistant proprietary

Protective metallic coating shall be zinc/aluminium alloy-coated steel AZ200 (200gsm/ m2) and having coating thickness (total both side) of 60µm or 0.06mm as stipulated in AS1397 – 2001.

(c) Primer

Custom formulated corrosion inhibitive chromate primer with nominal thickness of 5µm on each side.


6.2.1 - 41

(d) Finish/ top coat

The finish coat shall be custom formulated system and have dry film thickness 20µm on the top or weather side.

(e) Backing coat

Custom formulated polyester system in the standard Brass Grey colour with nominal film thickness of 10µm.

(f) Gloss

Paint finish shall have a nominal gloss level of 25 Gloss Unit @ 60° (D523).

(g) Properties

The coated finish for flashing and roofing sheet shall have the following properties:

(i) Impact Resistance: ≥10 Joules (AS 2728) (ii) Pencil Hardness: HB minimum (AS 2728) (iii) Flexibility: 7T or less, no cracking (AS 2728) (iv) Heat Resistance: Suitable for continuous service up to

100°C. Continuous service at higher temperatures may cause some colour change of the paint film

(v) Taber Abrasion Resistance: <20mg paint removal per 100

cycles (AS 2105) (vi) Certified as Class “O” under Early Fire Hazard Ratings

(AS1530)

(h) Product service performance

Property Measured After

Test Method

Results

Resistance to corrosion

1000 hours

Salt Spray Blister Density: ≤ 2 Blister Size: ≤ S2 Undercut from a score: ≤ 2mm No visible loss of adhesion

Resistance to Chalking

2000 hours Tapeoff Test, ISO 4628-6

Chalk Rating: ≤ 4

Resistance to Humidity

1000 hours No more than (1) blister density, no loss of adhesion


6.2.1 - 42

6.2.1.13.4 Aluminium Thermal Foil

The aluminium shall consist possess the minimum properties as follows:

Physical Properties Tensile Strength (ASTM D-828) Longitudinal Direction 10.5 KN/m Transverse Direction (TD) 6.4 KN/m Beach Puncture Resistance (T.A.P.P.I. T803m) 0.93J Water Vapour Permeance (ASTM E96 Procedure E) Uncrease Less than 1.13ng/Ns Crease (ASTM D1027) Less than 2.26ng/Ns Basis Weight 280gsm Reflectivity 0.95 Emissivity 0.05

6.2.1.13.5 Safety Mesh

The safety mesh shall also serving as a normal supporting weldmesh for roofing components. The mesh shall be at least 2mm galvanised wire with a tensile strength exceeding 450MPa. The longitudinal wires shall not be spaced more than 150mm centres with crosswires spaced at 300mm centres.

6.2.1.13.6 Fasteners and Washers

All fasteners shall be of AISI C1022 steel hardened heat treated or equivalent. The fasteners shall be coated with a min. 45µm Mechanical plated Zinc-Tin alloy (25-30% Tin), chromate conversion layer to passivate the zinc alloy and has special formulated polymer barrier to provide extra resistance to the environment. The corrosion resistance for the fasteners shall have AS3566 Class 4, equivalent or better. The proposed washer shall be used with right threshold level of carbon black to eliminate conductivity.

6.2.1.13.7 Sealant

Sealant shall be an approved adhesive material, suitable for application on all respects, of a consistency suitable for application providing a seal between a unit or structure. The colour selection of any visible exposed sealant shall be referred to S.O.’s selection


6.2.1 - 43

Test method Property Unit Value

Uncured – As tested at 50% RH and 23oC (73

oF)

ASTM D 2202 Flow (sag or slump) mm or inches 0 ASTM C 603 Extrusion rate g/minute 210 CTM 98B Working time minutes 15 ASTM C 679 Tack-free time minutes 35 Curing time days 7-14 CTM 97B Specific gravity Application temperature

range

oC -25 to 50

oF -13 to 122

As cured – after 7 days at 50% RH and 23

oC (73

oF)

ASTM D 2240 Durometer hardness Shore A 30 ISO 7389 Elastic recovery % 91 ISO 9047 Movement capability % ±50 ISO 11600 Sealant Class Low

Modulus 25LM F and G

Cured – after 28 days at 50% RH and 23

oC (73

oF)

12 x 12 x 50mm size T.A. joint (ISO 8339) 0.5 x 0.5 x 2 inches size T.A. joint (ASTM C 1135) Tensile at 25%

elongation MPa 0.3

Psi

40

Tensile at 50% elongation

Mpa 0.35

Psi

60

Modulus at 100% Mpa 0.4

Psi

70

Ultimate tensile strength

Mpa 0.75

Psi

120

Ultimate elongation at break

% 460

ASTM C 711 Service temperature range

oC -50 to 150

oF -58 to 302

CTM: Corporate Test Method.

ASTM: American Society for Testing and Materials. ISO: International Standardisation Organisation


6.2.1 - 44

6.2.1.13.8 Cleaning

(a) All metal work when finished shall be thoroughly cleaned of scraps and dirt. On large areas this shall be done as each section of the work is finished.

(b) The panels and components parts of the work that have been damaged (including finish) beyond successful repair shall be removed and replace, as directed by the S.O. or his agent.

(c) Swarf (metal scraps or or abrasive particles resulting from cutting and drilling) left on the surfaces of materials will cause rust stains which can lead to reduced life of the material. The Contractor shall ensure the installed and finished roof is free from swarf prior on a day to day basis. All metallic swarf and other debris from roof areas at the end of each day and at the completion of the installation shall be thoroughly swept or hose. If swarf has become stuck on a finish, it shall be carefully removed without removing the paint or the metal coating. The Contractor and his agent shall inspect the job two weeks after completion, after a rain or condensation that may cause any remaining swarf to rust and highlight affect the finished roof. Necessary repairs shall be carried out by the Contractor or his roofing specialist to the satisfaction of the S.O. without any time and cost implications to the Employer.

6.2.1.14 Pipework

(a) Impermeable plugs shall be installed in the pipe bedding for pipes

where the vertical gradient exceeds 1 in 10. Plugs shall consist of impermeable earth material (clay or similar approved material) 300mm thick laid across the full width of the pipe trench to the top of the pipe bedding material to prevent ground water running along the line of the pipe and washing fines out of the bedding and surround material. Plugs shall be installed at 20m intervals.

(b) Where, the horizontal and vertical alignment of pipes are required

for drain pipes, chemical pipes and other such small diameter pipes the Contractor shall design the horizontal and vertical alignment to suit all existing and proposed structures, services and ground levels. All pipes shall be laid at a minimum cover of 900mm unless specified otherwise. Where pipes can not be laid with 900mm cover for greater than 5 times the pipe diameter length, the Contractor shall provide a 150 thick grade C20 mass concrete surround to protect the pipe. Pipes laid above ground level shall only receive mass concrete surround where specified. All pipes with less than 1200mm cover under roads shall be provided with a 150 thick grade C20 mass concrete surround.


6.2.1 - 45

(c) The Contractor’s pipe design shall allow for all pipes to be drained to a washout at low points for maintenance and to an atmospheric break or an air valve at high points to prevent air blocks.

(d) All valves, flow meters, static mixers and other pipework fittings

internal or external to structures, that are subject to periodic removal for maintenance, shall be provided with a suitable flange adapter at one end of the fitting to allow its easy removal and replacement. The flange adapter shall be located to allow easy access for maintenance and removal (including any tie rods used) and shall be designed by the Contractor to resist the maximum anticipated thrusts at that location from internal pressures.

6.2.1.15 Yardpiping Works 6.2.1.15.1 Pipe Material

Unless otherwise stated and approved by S.O., the pipe materials to be used for the wastewater treatment plant shall refer to Mechanical Specification, or proposed by the Contractor if not provided or specified. The proposed pipe material and pipeline/sewer system for the wastewater treatment plant shall be as follows:

(a) Resistance to the chemical condition and properties for the

conveyance of the particular chemical;

(b) Resistance to sulphate attack from aggressive soils and groundwater;

(c) Resistance to corrosion in contaminated soils;

(d) Resistance to severe abrasion from aggressive soils and

groundwater;

(e) Resistance of the joint to infiltration and exfiltration; and

(f) Resistance of the joint material to corrosion and microbiological degradation;

(g) All underground pipes shall be supplied with bituminous coating

externally. 6.2.1.15.2 Trench Excavation

(a) Unless shown or stated otherwise, trench excavation and trench

widths shall be in accordance with General Specification for Earthworks.

(b) The sides of the excavation shall be supported by piling, shoring

and bracing as necessary to ensure the proper execution of the


6.2.1 - 46

work. The means of supporting the excavation and the materials proposed to be used for piling, shoring and bracing are to be submitted for review by the S.O. Where the excavation exceeds 4 metres in depth, the Contractor shall engage a QP to design and be responsible for the supervision of the construction and the stability of the temporary protection works. Drawings and details of such works shall be submitted to the S.O. for review 3 weeks prior to the commencement of the construction of the excavation and the temporary protection works.

(c) Excavations shall be kept free of all water, organic material and

rubbish and in a proper condition for pipe laying.

(d) Where the Contractor over-excavates, it shall make good the excavation at its own expense with sand or other material approved by the S.O.

(e) The bottoms of trenches or excavations shall be compacted prior

to the placing of any bedding or concrete materials. Should, in the opinion of the S.O., the foundation material be incapable of effective compaction, the material shall be removed and replaced with approved material.

(f) No pipes shall be laid until the trenches have been inspected and

approved. Spoil from trenches shall be deposited on the side of the trench opposite to that to be used as roadway, or elsewhere as directed. The toe of the spoil heap shall not be nearer than 600 mm to the trench, and care shall be taken that no spoil can run back into the trench.

(g) All excavated material, which is approved by the S.O. as being

suitable for backfill, shall remain the property of the S.O. and shall be spoiled or used as filling as directed within the Site. All excavated material, which is classified by the S.O. as unsuitable, shall be spoiled off-site.

(h) The Contractor shall be solely responsible for the maintenance of

excavations and is liable for any damage that may be caused to any water pipes, conduits, etc., through the collapse of the excavation.

6.2.1.15.3 Grading and Alignment in Trenches

(a) The Contractor shall determine the final alignment and grading of

all pipelines. All care shall be taken to preserve uniform gradients and correct alignment.

(b) Where shown on plans, bends shall be used to effect horizontal or

vertical changes of direction. Where such bends are not required, changes of direction shall be effected by angling the joints, by means of short lengths of pipes, or by means of cutting pipes and


6.2.1 - 47

using thimbles or collars to join them. However, no angling of joints will be permitted except where approved by the S.O. All such changes in direction shall be effected in curves of uniform radius. No joint shall be angled to such an extent as to impair its effectiveness and tightness. The pipe shall be truly in line for jointing and then deflected. The maximum deflection for each pipe shall not be greater than that recommended by the pipe manufacturer.

(c) Pipes shall be cut where and in such lengths as the S.O. shall

direct. No extra charge shall be made for cutting pipes or for additional jointing material or necessary labour.

6.2.1.15.4 Bedding and Filling Materials

(a) Standard bedding and filling for all pipes shall be an approved sand or other approved material with 100% passing the 2.36 BS sieve size and having binding properties but with linear shrinkage not exceeding two an one half percent.

(b) All bedding and filling materials shall be free from organic

material; gravel, stones, cobbles, rock fragments or other hard objects in excess of the specified sieved size; and from rubbish, and shall be non-aggressive to the pipe materials. Approved bedding shall contain not more than 0.3 percent of soluble salts.

6.2.1.15.5 Concrete Thrust Blocks

(a) Thrust blocks shall be placed between the fitting and the undisturbed side of the trench and shall be of dimensions as specified or shown in the plans. Where dimensions are not shown on the plans, the thrust block shall support the full barrel of the fitting but shall not cover the joint with the adjacent pipe.

(b) Thrust blocks shall be designed for action when the pipeline is

under test pressure. The Contractor shall be responsible for the determination of safe soil bearing pressures and shall take into account the loading orientation and the effects of soil saturation under flood conditions.

(c) Thrust blocks shall be constructed using concrete grade at least

30 MPa. The thrusts block, including ground bearing, shall be designed by the Contractor’s QP to ensure its effectiveness in providing necessary restraint and supports for the pipeline.

6.2.1.15.6 Filling of Pipe Trenches

(a) After laying of the pipes, approved filling shall be placed around

the pipe and to a minimum depth of 300 mm above the pipe


6.2.1 - 48

barrel. Approved filling shall be carefully placed to fill completely all spaces under and adjacent to the pipe.

(b) Where a fluctuating groundwater condition exists, and the grading

of the native soil and the embedment materials exhibit the following characteristics:

(i) (D85 coarse) is more than (5xD15 finer) in which:

(1) D85 finer = sieve aperture passing 85% of the finer material; and

(2) D15 coarse = sieve aperture passing 15% of the coarser material, or

(ii) (D50 coarse) is more than (25xD50 finer) in which:

(1) D50 finer = sieve aperture passing 50% of the finer material; and

(2) D50 coarse = sieve aperture passing 50% of the coarser material

then the S.O. may direct a filter cloth be installed in the trench to separate the two materials.

(iii) Filter cloth materials shall be non-woven fabrics approved by the S.O.

(iv) Free fall of approved filling onto the pipe shall be kept to a minimum but shall not exceed two (2) metres.

(v) Pipe collars or sockets shall not be overfilled before the completion of hydrostatic testing.

(vi) The approved fill shall be tamped thoroughly below, on each side and above the pipe in layers not exceeding 150 mm thickness. Care shall be taken in the removal of trench shields to ensure that full compaction is achieved as specified herein. Compaction of the filling material shall achieve a minimum Density Index (DI) of 70% as determined by Australian standard AS 1289 5.6.1.

6.2.1.15.7 Backfilling

(a) Commencement of backfilling

(i) Backfilling shall not commence until the Contractor has been so authorised or directed by the S.O.

(ii) The S.O. may direct that lengths of pipe lines which have not been tested shall be wholly backfilled to prevent floating of the pipes, or undue temperature movement, or that they be partially backfilled with the joints left uncovered until hydrostatic testing is completed.


6.2.1 - 49

(b) Other locations

(i) In other locations the selected backfilling material shall consist of either of the following:

(1) The best of the material (selected and approved by

the S.O.) from trench excavations, or (2) Material from “on site” earthworks selected and

approved by the S.O.

(ii) If, in the S.O.’s opinion, material from item (1) above is not suitable for backfilling then material from item (2) above shall be used by the Contractor.

The material used for backfilling shall not contain fractured rock or cobbles in excess of 100mm sieved size. Backfilling shall be carefully placed and packed so as to leave no voids. Precautions shall be taken to prevent any large pointed rock or other unyielding material from penetrating the approved filling towards the pipe barrel. The finer backfill material shall be placed first to ensure that the approved filling is well covered. Backfill material shall be levelled flush with the top of the trench, or slightly mounded along the line of the trench, as directed by the S.O. No rock or other hard unyielding material shall be left protruding above the surface of the backfill.

6.2.1.15.8 Chambers

The Contractor shall design and provide chambers for all valves, air valves and flow meters below ground level and manholes for all gravity pipes and access for maintenance. All chambers shall be designed against flotation and the thrust from pipeworks fittings, however the Contractor shall take precautions against flotation during the Construction stage. All chambers shall be provided with drainage.

6.2.1.16 Flushing, Testing of Mains

(a) General

(i) The Contractor shall supply all materials, plant, labour and equipment for the flushing, testing of mains. Flushing and testing shall be carried out to all the pipelines constructed under this Contract.

(ii) Prior to hydraulic pressure testing, the Contractor shall

flush all mains and connections. The rate of filling the mains with water shall be such that the water velocity therein shall nowhere exceed 0.05 m/s. Flushing shall be


6.2.1 - 50

done by scouring under pressure at all scours and valves as directed by the S.O.

(iii) Upon repair of all breaks which occur during or after

testing, the Contractor shall flush again that section of main as detailed above.

(b) Hydrostatic pressure testing

(i) Hydrostatic pressure testing shall be undertaken by the

Contractor on all pipework installed under this Contract.

(ii) Pressure testing shall be undertaken between valves and/or penstocks at each end of the pipework under test.

(iii) Where a pipeline ends without a valve, the Contractor shall

seal off the end of the pipeline to allow for the pipeline to be hydrostatically tested as specified herein. Sealing off shall be achieved by the provision of bolted on blank flanges or solvent welded on end caps. The end caps and blank flanges shall be fitted with stopcocks for filling of the pipeline and/or bleeding of air. The sealing off caps and flanges shall be removed after testing has been satisfactorily completed and the ends of the pipes shall be reinstated to the satisfaction of the S.O.

(iv) Pressure testing shall be undertaken as soon as possible

after the S.O. has agreed that the solvent welded joints and concrete thrust blocks have had time to develop adequate strength. The temperature of the piping material shall not exceed 40

oC during the test period. All tests shall

be carried out under the supervision and in the presence of the S.O.

(v) Care shall be taken to remove all air from mains under test

when filling with test water. The rate of filling of the test section with water shall be such that the water velocity within the test section shall nowhere exceed 0.05 m/s.

(vi) Subsequent to filling and prior to the formal pressure test

as detailed below, the water pressure shall be raised to a value equivalent to two-thirds of the pressure proposed for the hydrostatic test. This pressure shall be sustained for a period as directed by the S.O., sufficient to allow a thorough inspection of the section of pipeline under test for defects or failures. Any defects or failures that become evident shall be repaired in an approved manner by the Contractor at his own expense. Following repair, the water pressure shall be restored preceding the execution of the hydrostatic pressure test at the specified test pressure.


6.2.1 - 51

(vii) The hydrostatic pressure test shall be a constant pressure test unless otherwise specified. Valves within the test section shall remain open during pressure testing. The hydrostatic test pressure developed in the lowest section of the length of a main or mains under test shall be as set out below:

(1) Gravity mains shall be tested by closing off the

lowest point, i.e. the outlet, and filling the main until the water level at the inlet is 150mm below the overflow level.

(2) Pumped suction and delivery mains, unless noted otherwise, shall be tested to a pressure of 1.5 times their maximum design pressure or a minimum design pressure or a minimum of 400kPa whichever is the higher.

(viii) After pressurising the length of main or mains to the

required pressure, the section under test shall be allowed to stand without make-up pressure and shall be deemed to have passed the test provided that:

(1) there is no failure of any thrust block, anchor block,

pipe, fitting, valve, joint or any other pipeline component; and

(2) there is no visible leakage of the test water after at least 30 min under pressure, or after the time necessary to inspect all joints.

(ix) Where water losses occur during the hydrostatic pressure

test, the length of main or mains under test shall be carefully examined for defects and such defects shall be repaired in an approved manner by the Contractor at his own expense. The specified filling and hydrostatic pressure testing procedures shall then be repeated. This process shall be repeated as necessary until such time as the length of main or mains under test has satisfied the test criteria for acceptance, and there is no loss of pressure.

(x) All hydrostatic testing shall be carried out by the Contractor

at his own risk, and he shall provide all necessary labour and equipment for the satisfactory performance of the test or tests. This equipment shall remain the property of the Contractor.

(xi) Notwithstanding the satisfactory performance of

hydrostatic testing, the S.O. may exercise his own discretion to request that sections of main be uncovered for examination. If, after uncovering, any defect or defects are disclosed, the Contractor shall repair the defect or defects at his own expense. However, if after uncovering


6.2.1 - 52

of the main, no defects are apparent then the Contractor shall be paid the cost of uncovering plus ten percent.

6.2.1.17 Building In of Pipework and Other Items 6.2.1.17.1 Masonry

(a) Pipeworks

(i) Where pipework and other items are required to be built into masonry, wherever practical these should be built in as work proceeds. The S.O. may direct the Contractor to form box-outs during the masonry construction in accordance with details shown on the construction outline drawings issued to the Contractor by the S.O. or as directed by the S.O. on site for the subsequent building in of pipework or other items by the Contractor.

(ii) Precast concrete lintels shall be provided unless otherwise directed by the S.O.

(iii) Masonry proposed to be used to build around pipework and other items shall be of the same class and finish as the surrounding masonry, neatly cut to suit and with the finished masonry around the built in item of the same class and finish as the surrounding masonry.

(iv) All box-outs shall be fitted with a flexible water-stop to the centre of the wall or slab. The water-stop shall be joined onto itself to make it continuous for the perimeter of the box-out.

(b) Louvered Openings for Vents, Exhausts and Fresh Air Supply

The Contractor shall provide and install the louvered openings for the building vents, exhausts and fresh air supplies. The Contractor is responsible for the vents, exhaust and fresh air supply detailed design and is to confirm required sizing information to the S.O.

(c) Window and Door Openings

The Contractor shall design, and provide reinforced concrete or steel lintel beams for all door, window or other significant opening formed in brickwork walls for the Electrical and Control Room, the Store Room and any other building structure(s) that may be proposed for the Works. The floor level for the Electrical and Control Room shall be elevated from the platform deck level and the door openings shall be at a high point from the floor so that the ground level falls away from the door and prevent the ingress of water under the door. The Contractor shall provide ramps to the doors or provide elevated platform with staircases and handrails to suit access between the floating platform deck level and the building floor level.


6.2.1 - 53

6.2.1.18 Pipework Supports and Restraints

(a) All pipework fittings and valves laid above ground level shall be adequately supported for their self weight, thrust and the weight of the fluid they will contain. Pipe supports shall be designed by the Contractor and shall not restrict access to the pipes for maintenance. Details of proposed pipe supports shall be submitted to the S.O. for approval prior to installation of the pipework.

(b) All pipework that will experience thrust caused by working

pressures and test pressure within the pipework shall be adequately restrained. The Contractor shall design the thrust restraints to prevent thrust causing damage to the pipework or to surrounding structures. Thrust restraints designed by the Contractor shall make allowance for access to the pipework for maintenance and thermal expansion/contraction of pipework. Details of how thrust in pipework will be restrained shall be submitted to the S.O. for approval prior to construction of the pipework commencing. Submission shall include full calculations on expected thrust and the ability of the restraining material to withstand this thrust. Where pipework thrust is to be restrained by a structure then this shall be taken into consideration by the structural design of the structure.

(c) Pipework of a rigid construction shall be provided with movement

rocker pipes at all locations where it exits a rigid structure to a significant buried length (greater than 5 x pipe diameter). Polyethylene, uPVC or other flexible material pipes do not require a rocker pipe unless indicated otherwise in the manufacturer’s guidelines. Welded steel pipelines shall only be provided with rocker pipes where they are expressly recommended for the integrity of the pipe by the pipe manufacturer. The Contractor shall ensure that a high level of compaction to the pipe bedding and surround is achieved for welded steel pipes. All welded steel pipes shall be laid with a minimum 150mm thick granular bedding and a minimum of 150 mm compacted surround for pipes less than 500 mm Dia. Pipes exceeding 500 mm diameter shall be laid with a compacted granular surround of half the pipe diameter. The surround shall be laid and compacted against the excavated sides of the pipe trench to 0.5 pipe diameters above the crown of the pipe. Over excavation shall be back filled with compacted pipe surround.

(d) The Contractor shall design the steel pipe welds to withstand the

anticipated thrusts from the maximum design pressure including test pressures in the pipeline. All flange adapters and couplings should be tied to resist the thrust at that point.


6.2.1 - 54

6.2.1.19 Miscellaneous Structures

The structures to be constructed identified in the Scope of Works of this Specification and shown on the Drawings, shall also provide the following items under the civil scope.

6.2.1.19.1 Electrical & Control Room and Store Room

The Electrical & Control Room and Store Room shall be elevated from the floating platform deck and shall be free from any possible ingress of water that may accumulate at the deck. The floor elevation shall be high enough for any cabling that are required to enter through the floors for the Electrical & Control Room. The Contractor shall propose the layout for the Rooms including the electrical and control panels to S.O.’s approval. Other requirements as follows: (a) The Rooms shall be adequately designed for natural ventilation.

(b) The Rooms shall be enclosed with walls with vent and roof over.

There shall be at least 2.0m height clearance between the ceiling and the tallest panel to be installed in the room. At least 1.5m wide access shall be provided to the front side of the panel doors and have at least 0.6m clearance to all other fixtures.

(c) All openings to the Rooms, except the doors, shall be provided

with insect netting. Details for under the Schedule of Doors and Windows in this Specification.

(d) Access platform or staircase with handrail shall be provided to

access the Electrical & Control Room and Store Room from the floating platform deck level.

6.2.1.19.2 Plinths for Plant and Equipment

(a) Reinforced concrete plinths, metal skid or elevated frame support for tanks, up stands, pipe supports and miscellaneous metalwork shall be constructed to support plant and equipment and detail clearly on the Contactor’s drawings;

(b) All equipment and metalwork shall be raised a minimum of 30mm

above the finished floor level to avoid possible surface water ponding around equipment or metalwork base;

(c) Generally equipment and tanks shall be adequately raised to allow

efficient hydraulic flows across equipment or tanks; (d) For concrete plinth, all exposed edges for proposed concrete

plinth shall have a 25mm by 25mm chamfer and the platform level at least 150mm high.


6.2.1 - 55

6.2.1.19.3 Civil Works for Mechanical, Electrical and ICA Equipment

Installation Works

Necessary civil and structural works shall be carried out to facilitate and support for all installation works of mechanical, electrical and ICA equipment. Provision should be made as the construction advances to avoid coring of holes to the floating platform decks or tanks etc. This may include but not be limited to:

(a) Cast in puddle flanges for pipe penetrations through concrete

walls;

(b) Coring for pipe, duct or cable passage though concrete walls and slabs;

(c) Chasing for cable runs in concrete or brickwork and making good

afterwards;

(d) Demolition and disposal of minor structures obstructing equipment installation;

(e) Cutting of roads and structures to allow installation of pipe or

cable routes;

(f) Provision of temporary or permanent water supply and drainage as required for plant.

6.2.1.19.4 Safety Features and Facilities

(a) Adequate access and emergency escape from the Electrical and Control room and the floating platform shall be provided and indicated in the Contractor’s shop drawings.

(b) Safe access ladder and walkways shall be provided and installed

where required for safe access and escape from the wastewater treatment plant and equipment.

(c) Safety handrails shall also be installed at all walkways accessible

to workmen including but not limited to platforms elevated higher than 1.0m, the floating platform, the access bridge, the Platform structures for LIT and other working areas around the wastewater treatment plant. Anodised aluminium handrails and stainless steel ladders shall be provided at areas possibly in contact with the process liquids unless the proposed materials are reactive to the process liquid. All access ladders shall be coated with anti-slip material. Anodised aluminium handrails and ladder shall be provided at areas that are not subject to submerged condition.

(d) Standard safety buoys or ring lifebuoys with ropes and grabline

shall be provided around the periphery of the WWTP, and


6.2.1 - 56

mounted on structural columns but visibly unobstructed by equipments or structures. The lifebuoys shall face the WWTP, easily reachable and not mounted more than 1.5m from the deck. The lifebuoys shall be distributed equally around the sides of the floating platform and for both Platform structures for LIT. The lifebuoys shall be:

- bright rescued orange permanent colour; - high impact strength polyethylene and UV stabilised; - closed cell expansion foam, solid one piece units; - inside diameter 45cm, external diameter 75cm, depth 10cm; - supplied with highly visible floating lifebuoy lines or ropes

(10mm).

(e) Lightning protection to refer other Section under Electrical Works.

(f) The height of the each containment bunds for the respective chemical and fuel tanks it is designed to contain, shall have the capacity to hold the total volume of liquid stored in the tanks when full. An additional 100mm freeboard shall be provided to the height calculated.

6.2.1.19.5 Brickwork

(a) All brick walls greater than 1.0 m high shall be tied to a column or wall. Where the column or wall is an existing structure the Contractor shall anchor bolt the ties to the existing structure. The anchor bolts shall be designed by the Contractor to avoid existing steel reinforcement in a concrete column or wall and to not affect the structures strength or stability. Details of the proposed fixing arrangements shall be submitted to the S.O. for approval.

(b) Only brick work not receiving a permanent covering of plaster or

rendering, located above ground level and visible shall be fair facing brickwork. All exposed brick wall shall be plastered unless indicated otherwise.

6.2.1.19.6 Pipe Trenches

(a) Reinforced Concrete pipe trenches are to be provided in a distinct area of the works:

(i) Discharge pipeline crossing vehicular access (eg. the

existing bund location between access bridge and the sea).

(b) The pipe trench shall generally follow the route as shown on the

approved shop drawings. The Contractor shall carry out trial trenches and cable detection during design stage to determine any possible obstruction to the propose pipeline and whether


6.2.1 - 57

service diversion is required. The Contractor shall ensure that measures are in place to protect any existing services and ensure that there is no damage or disruption to the existing services.

(i) Where the pipe trench crosses the road, the pipe trench

shall be covered with removable heavy duty trafficable precast concrete sealed covers designed by the Contractor’s QP. The Contractor’s QP shall, in his designs for the RC trench structure, its foundation and the trench cover consider the following structural loadings in addition to those required under the Building Control Act and regulations:

- Vehicle loads (20-seater bus, loaded delivery trucks,

chemical and fuel re-filling tankers with 100% loads); and

- All anticipated construction load; - Vehicle max laden weight not lesser than 10ton; - Uniform distributed load not lesser than 20kN/m

2;

- Other form of loadings deem critical by the Contractor’s QP.

(ii) The pipe trenches that may receive surface runoffs and

groundwater shall have a concrete screed sloped at a minimum 1 in 200 fall to scupper drain and out of the trench or the sea. If there is a tendency that the trench may otherwise collect polluted waters, a sump located at the edge of the existing bund, shall be designed by the Contractor’s QP and constructed by the Contractor to drain the polluted waters.

6.2.1.20 Structural Steel Works

Structural steel works shall generally be in accordance with the standards and code of practices highlighted in this Specification for Standards Compliance (related to structural steel). The Contractor’s QP shall consider the parameters set out in this Specification for his design. Should the Contractor’s QP propose to change the parameters, he shall comply to the Building Control Act and Regulations and ensure that the design intent include the design class, material standards, steel grades and testing regimes to comply with the latest version of BC1. The design parameters adopted shall be clearly specified on the drawings and submit to the S.O. All structural steelwork shall be painted and protected against corrosion in accordance to this Specification for Paint Finishes and Protective Coatings for Structural Steel Works. (a) All bolts and nuts that are likely to come into contact with

secondary effluent or product water shall be Grade 316 stainless steel. All other bolts and nuts shall be hot dip galvanized.


6.2.1 - 58

(b) All protective coating to building structures shall be 2 hrs fire-rated.

6.2.1.20.1 Design, Fabrication and Erection of Structural Steel Roofs

(a) The Contractor’s QP shall design and detail all steel structures

including the steel roofs over the respective chemical storage tanks and dosage system. The structural design shall be reviewed by the Accredited Checker whenever necessary or required under the Building Control Act and Regulations and submit and obtain approval from the BCA. All costs associated in the designs and submissions shall be deemed to be included in the Contract Sum and shall not subject to an additional payment to the Contractor. The Contractor shall also manage all authority submissions undertaken by his QP and obtain approvals for the works. No additional of time will be provided for late submissions by the Contractor or his professionals unless the Contractor has valid reasons, subjected to the S.O.’s discretion.

(b) The Contractor shall provide detail information to the S.O. on the

source for the supply of the structural steel material. Method of statement for fabrication of structural steel works including the approved painting specification shall be submitted to the S.O. prior to the submissions to authorities and fabrication and erection.

(c) The Contractor shall engage a supervising QP including his

agents as required under the Building Control Act & regulations to be in charge of the supervision for the structural works. Critical joint connections eg. Welding inspection shall be undertaken by qualified test agencies and all aspect of the works shall be executed to the satisfaction of the supervising QP. All time and cost implications to complete the structural works shall be deemed to be included in the Contract and shall not be subjected to an additional payment to the Contractor.

(d) As required by Defence Science & Technology Agency (DSTA),

the height control limit for the subject site ranges from 48m to 100m AMSL. All structures and fixtures above the roof top, cranes, maintenance equipment, construction equipments, temporary equipments and lightning conductor shall not exceed the height limit. The Contractor may request for a copy of the height control plan if deem necessary.

6.2.1.20.2 Fabrication and Erection of Pipe Supports

The Contractor shall design, fabricate and erect pipe supports for pipes required for the works. The Contractor shall submit relevant drawings, specification and calculations by the Contractor’s QP for the pipe supports to the S.O. prior to fabrication and erection.


6.2.1 - 59

6.2.1.20.3 Fabrication and Erection of Steel Platforms, Access Walkways and Stairway

(a) The Contractor shall design, fabricate and erect steel platforms,

catwalks and stairways to provide access to equipment. Unless otherwise highlighted by the S.O., the access platform shall have a minimum design live load of 5kN/m

2.

(b) Access walkway and staircase shall normally have 1.0m width

clearance between railings with a minimum design live load of 5kN/m

2.

(c) The Contractor shall submit relevant drawings, calculations and

specification for the steel platforms, catwalks and stairways to the S.O. prior to fabrication and erection. As and when required by the Building Control Act and Regulations, the Contractor’s QP shall submit his design for authority approvals for the steel platform, access walkways, staircases, handrails and barriers.

(d) The Contractor shall provide handrailing to access areas where

there is a risk of fall exceeding 600mm or at the edge of a tank. All submerged handrailing shall be stainless steel grade 316, all other handrailing shall be anodised aluminium unless specified otherwise by the S.O.

(e) The Contractor shall design and provide chequer plate or grating

flooring for the proposed platforms or grating covers for chambers, sump and drains and indicated on drawings for S.O.’s approval. The plate flooring and grating covers shall be designed for safe operation of the works. All chequer plate flooring and covers shall be anodised aluminium designed by the Contractor with all necessary supports and edging to withstand a minimum loading of 5kN/m

2 without excessive deflection, minimize water ingress and

be easily removable by manual handling.

(f) All grating covers, steel pipe supports and other non structural steel fittings shall be hot dipped galvanized unless indicated otherwise. Structural fittings including steel platform, access walkway and staircase shall be painted and protected against corrosion.

(g) The Contractor shall provide adequate access to fresh air and

escape from all buildings and structures. Ladders and platforms shall be installed where required for safe access and escape from the wastewater treatment plant and equipment. Proposed location for safe access and escape route shall comply with industry best practices.


6.2.1 - 60

6.2.1.20.4 Fabrication and Installation of Structural Steel Associated with Lifting Devices, Cranes and Monorails

The Contractor shall design, fabricate and install the structural steel works associated with lifting devices cranes and monorails for the equipment installed in the Works. As and when required by the Building Control Act and Regulations, the Contractor’s QP shall submit his design for authority approvals for the structural steel frame for the lifting devices. Detail requirements for the safe working load required for the respective lifting devices is covered under the Mechanical works Specification, otherwise proposed by the Contractor in his design. The Contractor shall submit relevant drawings, calculations and specification for the structural steel works to the S.O. prior to fabrication and installation.

6.2.1.21 Aluminium Works

(a) Aluminium works shall generally be in accordance with BS EN1999-1 using marine grade alloys to EN AW 6061. Maritime structures designed to BS 6349, using aluminium and its alloys shall refer to BS EN1999-1 for full details of the engineering properties of the principal alloys for structural use. The Contractor’s QP shall comply to the Building Control Act and Regulations and ensure that the design intent include the material design standards, material grades and propose the testing regimes for the structural aluminium works. The design parameters adopted shall be clearly specified on the drawings and submit to the S.O.

(b) The Contractor’s QP shall design and detail the proposed

structural aluminium access bridge and the Platform structures for the Level Indicator Transmitter (LIT) for S.O.’s comment. The structural design shall obtain approval from the BCA and the Accredited Checker whenever necessary or required under the Building Control Act and Regulation. All costs associated in the designs and submissions including professional services to obtain regulatory approval for the proposed structure shall be deemed to be included in the Contract Sum and shall not subject to an additional payment to the Contractor.

(c) The Contractor shall provide detailed information to the S.O. on the source for the supply of the aluminium and marine grade aluminium. Method of statement for fabrication of structural aluminium works shall be submitted to the S.O. prior to actual fabrication and erection.

(d) The Contractor shall engage a supervising QP including his

agents as required under the Building Control Act & regulations to be in charge of the supervision for the structural works. Critical joint connections eg. Welding inspection shall be undertaken by qualified test agencies and all aspect of the works shall be executed to the satisfaction of the supervising QP. All time and


6.2.1 - 61

cost implications to complete the structural works shall be deemed to be included in the Contract and shall not be subjected to an additional payment to the Contractor.

6.2.1.21.1 Design, Fabrication and Erection of Access Bridge

(a) The Contractor’s QP shall design and detail the proposed access bridge that connects the floating platform and the perimeter bund. The access bridge may be an independent structure supported by an A-frame with wire rope suspension system or founded on the bund and supported on a pin-connected structure integrated with the floating platform. The design for the access bridge support must have allowance to for rotation due to high and low water levels and wave action. The water levels will fluctuate between tide levels (before the bund is closed) and in the permanent situation from +1.5m to +2.5m CD with additional allowances from the design limits to be determined by the S.O.)

(b) The access bridge shall have a clear width, not lesser than 4.5m.

Vehicular impact guardrails shall be mounted along the access lane to protect the structural elements of the access bridge. The access bridge shall also have structures to support pipeline(s) between the wastewater treatment plant and the bund. The pipeline(s) shall be easily accessible from the access bridge and protected against accidental damage from vehicles.

(c) A security gate is required at the entrance (bund side) of the

access bridge. The gate shall be mounted close enough to the access bridge with gap between the bridge and the gate not greater than 100mm to prevent unauthorised entry by the public. The Contractor shall in his design provide additional robust steel concertina wires along the external sides of the access bridge where the bridge bottom level and the immediate ground level is lesser than 3.0m to prevent the public from accessing the bridge structure. The gate shall be see through and come with a secure locking system. The gate design shall not have any intermediate foot rest that may allow intruders from climbing the gate. The gate may be integrated with a height barrier (for 4.0m height clearance). This height barrier shall serve to prevent accidental impact to the pipe-bridge(s) that may be proposed for the wastewater treatment plant. Any gap between the gate and the height barrier structure shall not be more than 100mm. The security gate and the height barrier may be constructed from steel but shall be painted and properly coated against corrosion.

(d) The foundation supports for the access bridge shall be designed

by the Contractor’s QP.


6.2.1 - 62

6.2.1.21.2 Design, Fabrication and Erection of Platform Structures for Level Indicator Transmitter (LIT) (a) The Contractor’s QP shall design and detail the proposed the

Platform structures to allow for access to the LIT, including other equipments like wireless adapter and a control box. There shall be two numbers of such Platform structures – one that goes towards the sea and the other towards the Phase II Cell where the WWTP is in. The mountings for the LIT and all other equipments for it will be located at the end of the Platform structures (away from bund). The Platform structures will have piers that are partially submerged in water. These Platform structures, including the platform deck plates and handrailings shall be constructed from marine grade aluminium. The Contractor shall liaise closely with the manufacturer of the LIT to determine the height requirements and design requirements for the support mounting the LIT.

(b) The Platform structures shall normally have 1.0m width clearance

between railings with a minimum design live load of 5kN/m2. The

piers and the foundation shall resist any impact loading from approaching vessels to Contractor’s QP design.

(c) The Contractor shall include in his design, supply and installation

of stainless steel grade 316 security box(es) for the LIT and the control box with locks. All the equipments to be mounted on the support shall be accessible.

(d) The foundation supports for the Platform structures (for LIT) shall

be design by the Contractor’s QP and ensure the bearing on the flat-bedded shore is adequate to take the design loading.

(e) At each entrance of the Platform structures (for LIT) at the bund

side, a security gate is required to prevent unauthorised entry into the platform and the LIT. The gate shall be constructed from marine grade aluminium. The gate shall be at least 2.2m high and the top lines with concertina wires. Unless the platform deck is above the immediate ground level by at least 3.0m, robust concertina wires should also be placed on both external sides of the Platform structures.

(f) The Contractor shall consult with the MPA and obtain approvals

for the construction of the proposed Platform structure within the sea area under MPA’s jurisdiction. The Contractor shall be deemed to have priced in the Contract all necessary fees and costs in compliance to MPA’s requirements for the proposed construction. There shall be no cost and time implications claimable by the Contractor against the Employer for compliance to MPA and any other related authorities’ requirement.


6.2.1 - 63

6.2.1.22 Contractor’s Designs for Submission to Authorities and Technical Department

6.2.1.22.1 Scope of Contractor’s Design

The Building Control Authority Act requires building and structural works to be submitted by a QP. To the extent as required by the Building Control Act and Regulations, the Contractor shall engage relevant professionals including architect where specified to design and make submissions to BCA for the following works, but not limited to:

(a) All temporary works; and

(b) All permanent building works as described under this Specification

for civil scope of works, including backfilling earthworks, structural steel roofs, access bridge, pipe rack or pipe-bridge, electrical and control room, reinforced concrete foundations, access platforms, elevated frame supports for tanks and equipments, underground trench, valve chambers, Platform structures for LIT, handrails, pipe supports, cable supports, utilities supports, etc.

It shall be the Contractor’s responsibility to obtain approval(s) from the relevant authorities and technical department for all the proposed works. The Contractor’s QP shall apply and obtain from the Commissioner of Building Control for a Certificate of Statutory Completion (CSC) or a Temporary Occupational Permit (TOP) before the building and structural works can be considered as completed.

6.2.1.22.2 Temporary Works

As a minimum, the Contractor shall provide the followings:

(a) To the extent as required by the BCA Act, the Contractor shall engage a QP to prepare all necessary drawings, calculations, reports, forms, information, records, etc, on all the temporary works and submit directly to BCA;

(b) The Contractor shall provide the S.O. carbon copy of all the

documents submitted to BCA;

(c) The Contractor shall only proceed to construct the temporary works upon statutory approvals are granted, where required; and

(d) The Contractor shall bear all fees, expenses and costs for the

submission to BCA and all other related regulatory authority, agencies and technical department.


6.2.1 - 64

6.2.1.22.3 Permanent Building Works designed by the Contractor

As a minimum, the Contractor shall provide the followings:

(a) The Contractor shall engage Registered Surveyors to conduct all necessary topographical and hydrographical surveys and prepare all necessary drawings, information, records, etc, on all the existing grounds and the as-built works designed and constructed by the Contractor;

(b) The Contractor shall engage relevant QP (including specialist QP

eg. QP (Geotechnical)) and architect to prepare all necessary drawings, calculations, reports, forms, information, records, etc, on all the permanent works designed by the Contractor, as specified;

(c) All coordination and pre-consultation meetings with all the relevant

statutory departments and including Accredited Checkers (Civil, Structural and Geotechnical), where relevant. The Contractor’s QP shall be present to facilitate these meetings and coordination;

(d) Necessary drawings, calculations, reports, forms, information, etc,

endorsed by the relevant QP or architect for the S.O. to make the statutory submissions;

(e) The Contractor shall only proceed to construct the units upon

statutory approvals and the Permit to commence work from BCA are granted; and

(f) Provide the S.O. with as-built drawings, calculations, forms,

information, etc for submission to necessary statutory authorities and Technical Departments to obtain the Temporary Occupation Permit and Certificate of Statutory Completion.

6.2.1.23 Signages 6.2.1.23.1 Scope of Works

(a) This section covers the signage to be installed as part of the features of the WWTP.

(b) The Contractor shall propose and provide the following type of

signages wherever applicable.

Description/Type Location

Name Tags All tanks, bunds, equipments and pumps, emergency wash station, Electrical & Control room

Warning Signs At all security gates

Location Map Within WWTP premise (to be advised)


6.2.1 - 65

Safe working load (SWL) signs

Access bridge, Platform structures for LIT, access platform around equipment and tanks, pipe-bridge(s), floating platform, all lifting hoist

Height Limit signs Height limit barrier, pipe-bridge(s)

Exit signs Within WWTP premise (to be advised)

Speed Limit signs Height limit barrier, Within WWTP premise (to be advised)

Safety signs Within WWTP and Platform structures for LIT (to be advised)

(c) The details of the sign message and artwork of sign plate shall be

proposed by the Contractor and submitted to the S.O. for comments and approval during construction stage. The Contractor shall also provide samples and submit shopdrawings in their proposals prior to construction and installation. The cost of samples, design, supply and install works for signages shall be deemed to be included in the Contract Sum.

6.2.1.23.2 Materials and Workmanship

(a) Unless otherwise, stainless steel 316 and aluminium grade of 1150 shall be used for the construction of the signs;

(b) Sign message panel shall be rigid, stable and not subject to

distortion or corrosion. Support posts for free standing signs shall be sufficient strength to support the message panels.

(c) The Contractor shall submit samples of paint and finishing to be

used for the sign plate and support together fixing devices for the approval of the S.O. All painting and finishing materials to be used shall be of vandal and weather proof type.

(d) Sign materials shall conform to ASTM or approved equivalent

standards.

Date post:	18-Jul-2016
Category:	Documents
Upload:	daison-paul
View:	34 times
Download:	3 times

6.2.1 - Civil and Structural Works

Documents