Manjung Power Station - Malaysia

Manjung Power Station CW Intake Culvert

End of Contract Report – Volume 1

MANJUNG POWER STATION MALAYSIA

Offshore Cooling Water Intake Culvert Leighton LAMA Joint Venture

END OF CONTRACT REPORT July 2000 to October 2001 Leighton-LAMA Joint Venture

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Table of Contents

VOLUME 1 – MAIN REPORT SECTION 1. SECTION 2. SECTION 3. SECTION 4. SECTION 5. SECTION 6. SECTION 7. SECTION 8. SECTION 9. SECTION 10. SECTION 11. SECTION 12. SECTION 13. SECTION 14. SECTION 15. SECTION 16. SECTION 17. SECTION 18. SECTION 19. SECTION 20.

Leighton-LAMA Joint Venture

INTRODUCTION JOINT VENTURE RELATIONSHIP PRE CONTRACT AWARD BRIEF PROJECT DESCRIPTION DESIGN OF THE COOLING WATER INTAKE GEOTECHNICAL CONDITIONS ENCOUNTERED ON THE CULVERT ROUTE PRODUCTION RATES, PLANT UTILISATION AND CREW SIZES COST VS BUDGET RISKS/LESSONS LEARNED STAFFING LEVELS SUBCONTRACTORS & SUPPLIERS TEMPORARY WORKS PRECASTING OPERATIONS IN-SITU CULVERT & COFFERDAM MARINE WORKS DOSING LINE NAVIGATION STRUCTURE FINANCIAL SITE PHOTOGRAPHS APPENDICES – CD OF DRAWINGS

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SECTION 1. INTRODUCTION 1.1. SCOPE The contract is for the construction of a Cooling Water Intake System as part of the Manjung Power Station. The plant is coal fired, utilizing available sea water for cooling purposes. The project is constructed on a joint venture design and construct basis between Leighton Contractors (main civil subcontractor for the Manjung Power Station Project) and LAMA International Contractors (Design and specialist Marine Works Contractors.) The purpose of the structure is to draw and deliver seawater, from 1500 metres offshore, to the power station cooling system on land, at a rate of 88.2m3/sec when in full operation. This requirement is being achieved by the construction of a sub-sea triple celled culvert, 1500 meters long. This culvert was constructed over a period of 13 months, involving land and marine construction operations, including a substantial amount of underwater work using divers. The locations of the seawater intake points have been carefully selected based on the tight specifications for minimum depth of water, water temperature, and the turbidity of h te seawater. The project has been carefully designed and constructed to ensure that the clients’ requirements are met in full, with due consideration for the environment, local authorities requirements, constructability, programme and budget. 1.2. PROJECT DESCRIPTION Name of Client: Joint Venture Partner: Location: Type of contract: Initial Budget:

Leighton Contractors (Malaysia) SDN BHD Leighton Contractors (Malaysia) SDN BHD Lekir, Perak Darul Ridzuan, Peninsular Malaysia Design and Construct Lump Sum Design MYR 1 677 000.00 Construction - MYR 60 000 000.00 Final Cost: Design MYR 1 883 998.47 Construction - MYR 63 250 000.00 Planned Programme: Completion - July 2001 Actual programme: Completion - October 2001

Leighton-LAMA Joint Venture

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Manjung Power Station

1.3. PROJECT SUMMARY The design and construction of the cooling water intake culvert consists of the following: • • • • •

• • • • • •

Dredging of 380 000 cubic metres of in-situ material to form the sub-sea trench for the culvert. Underwater piling using 312 no 1000mm diameter spun concrete pipe piles to tight positional and level tolerances using GPS equipment. Placing of reinforced pre -cast pile caps underwater and the underwater grouting of these pile caps into the piles. Manufacture and handling of 142 no, 10 m long, 3 celled, pre -cast concrete culvert units, each weighing 400 tonnes. Transporting of these 400 ton pre -cast culverts on land, using heavy lift trailers, and at sea using a specially designed floating gantry to place them in line in the pre-dredged sub-sea foundation trench, to form the triple celled culvert at depths varying between – 8m and –16m ACD. Underwater grouting operations to seal the joints between the culvert units, to prevent ingress of silt or sand. Construction, handling and placing of 6 no pre -cast intake units weighing 150 tonnes each, offshore at the end of the cooling water intake culvert. Construction of a load out jetty to facilitate loading out of the precast concrete units. Construction of 70 metres of in-situ concrete culvert within a 12m deep cofferdam to provide the connection from the offshore precast concrete culverts to the land based water pool, which is the reservoir for the power station’s intake cooling water pumps. Installation of three 225mm diameter 1450m sub-sea pipelines for the delivery of hypochlorite to the intake structures at the end of the culvert, to prevent marine growth inside the cooling water intake system. Design simulations, including physical and computer modelling, as well as on site testing, formed a major part of the successful design and construction of the project.

Leighton-LAMA Joint Venture

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SECTION 2. PRE CONTRACT AWARD This section deals with the contractual process prior to award of contract. The first contact took place in October 1999 with Leighton (Malaysia) requesting LAMA to assist them with the preparation of a price which was to be submitted to Peremba for the construction of an intake and outlet conduit for a new power station to be constructed at Manjung in Malaysia. Various alternative designs were considered, including steel, HDPE and concrete pipes, all in a buried trench, concrete pipes above sea level supported on a piled structure and concrete culverts in a trench on the seabed. A budget price was submitted by LLJV to Peremba on 18 October 1999 based on steel pipes with an HDPE alternative. The price was developed further to exclude the outlets and an option of steel pipes on trestles above water was also priced and a budget price was submitted on the 1st November 1999. In January 2000 negotiations moved from Peremba to Alstom (who had been presumably awarded the Main Contract at that stage). No pre-bid agreement between ourselves and Leighton was put in place at this stage due to the nature of the discussions being around budget pricing etc. rather than the submission of a formal tender. Leighton were now also in negotiations with Alstom regarding the Main Civil Works Contract. At this stage Alstom produced their first Design and Construct Specification, which was to be used for the design of the intake conduits, whichever option was selected. At this stage, however, Alstom had still not decided whether the contract would go out as a D&C or whether they would design it themselves to their own design, or thirdly whether they would carry out the design based on the contractors chosen type of conduit. During the mo nth of January 2000, various options based on a steel pipe in a trench on the seabed were priced in order to reduce the contract sum. A presentation was made by the Leighton-LAMA team to Alstom on the proposed scheme at that time. Leighton had also requested prices from Van Oord and See Yong & Sons. A further alternative, that of precast concrete culverts was developed, which started looking like being the most cost effective solution. The development of the preliminary design of the culvert then commenced in more detail, in order to further refine the costs of this system. The basic sizing was taken from Alstom layout drawings showing an internal cell size of 3.42m square. A budget price based on precast concrete culverts was submitted on 29th January 2000. This price was developed and reduced further during the month of February 2000. The price which Leighton submitted for the overall Civils Works included the offshore work based on a price and submission from See Yong (assumed immersed tube construction) as LAMA were not prepared to agree to a fixed price at that stage due to the short time given to price the works. Leighton was awarded the Civil Works Contract including the offshore works as an option to be taken up before end May 2000. At this stage pricing of the culvert system based on Alstom doing the design as well as the project being carried out as a design and construct contract, were carried out in parallel, as there was still no confirmation from Alstom as to which way they were intending to go. In February an internal Tender review report states that Alstom have indicated that they would consider a EPC type of contract in order to advance this part of the works but might still insist on completing the design themselves. This report also discusses two possible bid strategies being: 1. Alstom doing the design and 2. EPC type of contract. Leighton-LAMA Joint Venture

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Both options were priced assuming different design fees as well as variable contingencies to cater for the design risk. By mid-March 2000, there was still no confirmation that LAMA would be responsible for the permanent works design. During the week ending the 19th May, we were informed by Leighton that Alstom required the JV to do a presentation on the proposed culvert design with a view to awarding the offshore contract on a design and construct basis by the beginning of June. This was the first time that Alstom had confirmed their intention to go the D&C route. A LAMA team travelled to Kuala Lumpur on the 20 th May to make the presentation to Alstom and then spent the next 10 days finalising the design and price. A revised Performance Specification was issued by Alstom as the basis on which the D&C contract was to be awarded. The main issue at that time was the interface between the offshore works and the waterpool, and a solution was arrived at by the Leighton-LAMA team based on a pipe -jacking operation. LAMA’s design fee was adjusted during the final pricing and was based on the scope of work as defined at that time. Discussions were also held with Nelson Borch of TerraGeotechnics (through Peter Furness) for them to assist in both the design approval process as well as providing specialist geotechnical advice. After submission of the price, various negotiations took place between Leighton and Alstom and a final price of RM 63.25M for the Offshore Works was agreed to, although at this stage it was still not clear what our involvement would be. Leighton notified LAMA during the first week of June that they (Leighton) had been awarded the offshore contract. A LAMA team then travelled to KL to finalise LAMA’s involvement, the JV agreement, and to discuss staffing and the programme for the contract. It was at this stage that a revised JV agreement and consultancy agreement appeared for the first time and LAMA was asked to sign it as a basis of LAMA’s design responsibility to Leighton. During this visit in June discussions were held with the site team (including the Project Director) and a decision was made to change from pipe-jacking to a cofferdam for the inshore tie-In to the waterpool. A potential standoff position developed on this visit between Leighton and LAMA around issues of representation in the JV, the JV Agreement, Indirect Cost split, sponsors fees and profit. Leighton’s view was that the marine work had been secured by Leighton as LAMA had not appeared willing to commit themselves at the time of the original price submission. Leighton threatened to ‘drop’ LAMA if no agreement could be reached on the outstanding issues which were only finally resolved at the first JV EXCO meeting. Leighton’s initial requirement was that the responsibility for the design of the works be directly between Leighton as the Main Civil Works Contractor and LAMA. After discussions at the first JV Exco meeting on 5 September 2000, it was agreed that if there was going to be a formal agreement, then the agreement should be between the LAMA and the LLJV and not directly through Leighton.

Leighton-LAMA Joint Venture

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SECTION 3. JOINT VENTURE RELATIONSHIP 3.1. BACKGROUND Referring to Section 2 it will be noted that Leighton played the major role in securing this project. This was largely due to the fact that Leighton had already secured the main civils contract and the CW Inlet was to be a sub-contract to the civils package. Because of this existing relationship with the client, all pre -award negotiations were through Leighton, with technical and pricing backup being provided by LAMA. At the first JV meeting held in Malaysia in June, just after the contract award, a new format of joint venture agreement and joint venture exco was proposed by Leighton. This differed to those previously used and clearly the intention of Leighton was to reduce the role of LAMA in joint venture decision-making. This was considered to be unacceptable to LAMA and eventually it was agreed by the parties to revert to the standard Leighton LAMA JV agreement previously used on the JV projects. 3.2. DURING THE CONTRACT EXECUTION The relationship between the Leighton and LAMA Staff on site during execution of the project was generally good, but between the Parties was complicated by two factors: • •

The JV was executing the work as a subcontractor to Leighton, and the project director of the Civils contract (a Leighton’s contract employee) also acted as the Joint Venture Project Manager. LAMA was carrying out the design works on a lump sum basis for the joint venture. On previous projects generally the design was carried out by LAMA within the Joint Ventrure and at the JV’s risk.

3.2.1.

Subcontract to Leighton Contractual issues LAMA commenced work on the project only having seen a generic Leighton’s Sub contract agreement. The proposed agreement was only prepared after the details of the CW Inlet subcontract were concluded between Leighton and the Client, which was some months after the start of the project. The proposed conditions were unacceptable to LAMA, but Leighton refused to accept any changes to their “standard subcontract agreement” The result is that this subcontract agreement remains unsigned. Management issues Leighton had, at the start of the works stated that the main civil works took precedence over the CW Inlet and they would not permit a disagreement between the parties to jeopardise progress on the main contract. All negotiations with the Client which were of a commercial nature were dealt with by Leighton as they were the Main Contractor, and LAMA was generally excluded from these discussions. Very little in the way of correspondence between the main contractor and client which was of a commercial nature was made available to LAMA or the JV management on site. Agreements on issues such as incentives, bonus’s, penalties and commercial issues surrounding the geotechnical problems were only received second -hand from Leightons.

Leighton-LAMA Joint Venture

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It was agreed at the start of the contract that the Leighton’s Project Director on the Civil Works would also act as the JV’s Project Manager for the CW Inlet, despite LAMA having placed a very experienced Project manager on site. The commercial support to the JV was provided by the Leighton’s Commercial Manager on site. Some of the Leighton staff found it difficult to be even-handed in their dealings with the two JV Partners and in particular their approach taken in regard to LAMA’s claim for additional design costs and the resolution of the Geotechnical problems were questionable. LAMA were treated as sub -contractors by the Leightons Management although they were also JV Partners. 3.2.2.

Design Works The decision by the Client to award the CW Inlet on a Design & Construct basis was only made at a very late stage in the contract negotiation stage. With the very tight program, and the impact that the CW Works had on the Main Civil works, the design team were put under pressure from the start of the project. In particular, the design of the cofferdam at the waterpool, and later the revised founding to the culvert units consumed a much greater design effort than was previously assessed. Leighton at an early stage raised a number of issues with regard to their perception that the design which LAMA was carrying out was overly conservative and more expensive to construct than tendered. These perceptions were largely unfounded. The greatest influence on the JV relationship was brought about by the geotechnical problems encountered with the culvert foundations (elsewhere detailed). These problems led to a change in design in the foundations, with the resultant increase in cost. Although the decision to change the foundation system was made relatively quickly it resulted in a polarisation between the parties which was never completely repaired. There was a large amount of additional design work carried out for the project as a result of, amongst other things: • Cofferdam design, as a result of the variable ground conditions, and to suit piling methods and materials. • Redesign of various plant items to suit the requirements of the site team. • Redesign of the “Temporary Jetty” in order that it satisfy the requirements of a permanent structure. • Change of the culvert foundation to a piled solution • Design of the navigation structure. • Dosing line change Although the design work was done as a Lump Sum, additional compensation was requested for some of the additional work, especially where the additional work was done to suit the site requirements. An agreement was reached on payment for certain of the minor additional work, but despite lengthy submissions and discussions with Leighton on the balance, they argued that much of this redesign was merely design development; no additional structures were built than were tendered, and therefore there were no grounds for additional payment to the designers.

Leighton-LAMA Joint Venture

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In fact, in the final negotiations with Leighton on the settlement of the piling foundation claim, all design variation costs (including those agreed to be paid) were forfeited by LAMA. 3.3. LESSONS LEARNT •

‘Conflict of interest’ issues must be identified and dealt with in appropriately worded agreements.

•

The potentially disastrous arrangement of sub -contracting to your Joint Venture Partner can severely stress the Joint Venture, particularly when technical or financial problems are encountered on the project. Similar joint venturing arrangements were in place on Sha Chau (with Leighton) and on the Natal Pipelines (with Pentow Marine). The Sha Chau project had no technical problems and was financially very successful so the relationship was never tested and remained good. The Natal Pipelines project had technical and financial problems and led to a breakdown in the Joint Venture relationship.

•

Ideally, the design risk and the cost of producing the design should be shared by the partners in the JV and not transferred to one of the partners. In this way the cost vs. benefit of design development can best be managed.

Leighton-LAMA Joint Venture

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SECTION 4. BRIEF PROJECT DESCRIPTION The cooling water intake culvert is approximately 1490m in length, extending from the intake structures at the seaward end to the diaphragm wall of the pump station water pool onshore. The triple cell culverts have interior barrel dimensions of 3.750m vertically and 3.450m horizontally, with 0.300m chamfers. The culvert consists of an in-situ section, 142 pre-cast sections with 6 intake towers towards the end, 3 x 225mm HDPE dosing lines on top of the culvert and a navigation structure 50m offshore of the end of the culvert. These items are described in more detail below. 4.1. IN-SITU CONCRETE CULVERTS

Water pool Opening into In -Situ Culvert

Cofferdam for In-situ Culvert

The in-situ concrete culvert is 70m long, which was constructed in three sections i.e. one 10m and two 30m long sections, from the open trench through the island revetment to the connection to the water pool diaphragm wall. Each section was constructed within a sheetpiled cofferdam. All the sheet piles were removed after construction with the exception of the sheet piles up against the diaphragm wall of the water pool. The diaphragm wall of the water pool in the region of the tie-in to the in-situ culvert, was cast prior to the construction of the in-situ concrete culvert. A reinforced concrete chimney, which provides access to all three barrels, is positioned towards the end of Section 1. This concrete chimney allows the three interior structural steel bulkheads to be installed into the barrels of the in-situ culvert. The bulkheads were required to retain the water in the culvert during the construction of the opening in the diaphragm wall of the water pool. The existing VIB wall surrounding the bulk of the power station civil works cuts across Section 1 of the culvert. There are movement joints between each section of the in-situ culvert and at the connection to the external face of the cooling water pool. Heavy-duty water bars were installed at the movement joints between the in-situ culvert sections as well as the connection to the water pool wall. The reinforcement in the concrete culvert is not continuous across these joints. The poor soil conditions in the area where the cofferdam was constructed, as well as the large future settlements predicted for this area, dictated that the in-situ culvert needed to be supported on pre -cast concrete bearing piles. Pre-cast reinforced concrete piles provide support to the culverts, positioned in four rows longitudinally under the culvert walls. The longitudinal pile spacing varies along the length of the in-situ culvert. The in-situ concrete

Leighton-LAMA Joint Venture

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culvert is underlain by a 75mm concrete blinding layer. The piles penetrate the 75mm blinding layer to tie into the reinforced concrete culvert base slab. The culverts are founded at approximately –7,680m ACD (underside concrete floor), with the top of the concrete roof at –3,070m ACD. Over Section 1, fill is placed to a level of +4,650m ACD. The fill slopes down through the revetment over the length of Section 2 to meet the general seabed level of –1,600m ACD. This level is maintained over the full length of Section 3. 4.2. PRE-CAST CONCRETE CULVERT UNITS

Typical Pre -Cast Unit

Pre-Cast Unit being placed by Gantry

The cooling water intake consists of 142 Pre -cast Concrete units extending from the in-situ culvert to the end of the intake culvert, which are divided into 11 different types as follows:

Pre -cast Culvert Units Type A and B.

Unburied Unit 54 Type A Buried Unit 71 Type B

Units type A and B are installed in a dredged trench and are supported on 4 concrete pile caps which are supported on 4 No. 1m diameter, class C, grade 80N/mm2 concrete spun piles. The cooling water intakes consist of 54 No intake culvert type A & 71 No intake culvert type B units, which are each 10m long, 11.810m wide by 4.610m high overall. Unit type A and B’s are triple cell pre -cast culvert units, which have interior barrel dimensions of 3.750m vertically and 3.450m horizontally, with 0.300m chamfers. Unit type B’s are identical to unit type A’s except that they have more reinforcement in them to cater for a greater cover of seabed material due to their location in the length of the intake culvert. Pre -cast Culvert Units Type F.

Access Unit 6 Type F

Units type F’s are installed in a dredged trench and are supported on 4 concrete pile caps, which are supported on 4 No. 1m diameter, class C, grade 80N/mm2 concrete spun piles. The cooling water intakes consist of 6 No intake culvert type F units, which are each 10m long, 11.810m wide by 4.610m high overall. Unit type F’s are triple cell pre-cast culvert units, which have interior barrel dimensions of 3.750m vertically and 3.450m horizontally,

Leighton-LAMA Joint Venture

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with 0.300m chamfers. Unit type F’s are the units that have the 3 manhole covers in them in order to access the inside of each of the 3.750m x 3.450m barrels. Pre -cast Culvert Units Type H

Transition Unit 1 Type H

The transition unit type H is the first pre -cast unit that will be placed in front of Section 3 of the in -situ concrete culvert. The north end is cast at an angle to match the south end of Section 3 of the in-situ culvert. The transition unit Type H is 8.180 m long along the centre line and is 11.810 m wide x 4.610 m high overall. Reinforced concrete piles provide support to the transition pre-cast unit Type H as follows: • •

2 No. 1000 mm diameter concrete spun piles, positioned longitudinally under the external culvert walls, on the offshore end of unit Type H as per the typical pre-cast unit and; 2 No. 700mm diameter concrete spun piles, positioned under the internal walls of the culvert, at the joint between Section 3 of the in -situ culvert and the transition pre-cast unit Type H. A continuous crosshead beam and 2 no. rectangular pile caps are cast over the 2 No. 700mm diameter concrete spun piles to support the pre-cast transition unit Type H.

Pre -cast Culvert Units Type J&K

Intake Unit 3 Type J

Intake Unit 3 Type K Units type J&K are installed in a dredged trench and are supported on 8 concrete pile caps which are supported on 8 No. 1m diameter, class C, grade 80N/mm2 concrete spun piles. The cooling water intakes consist of 3 No intake culvert type J & K units, which are each 10m long, 11.810m wide by 4.610m high. The triple cell pre-cast culvert units have interior barrel dimensions of 3.750m vertically and 3.450m horizontally, with 0.300m chamfers. They are similar to a typical unit except that they have a 3.450m square opening in the top slab, which incorporates an up stand beam cast around the opening which caters for the in situ connection of the pre -cast Intake towers to the pre-cast units. The unit types J&K also have internal walls for diverting and channelling the water flow into the culverts. Units J & K support the 6 No. Intake Tower Structures at the end of the intake culvert. Pre -cast Culvert Units Type L&M

Unit Right 1 Type L Unit Left Type M Units type L&M are installed in a dredged trench and are supported on 4 concrete pile caps which are supported on 4 No. 1m diameter, class C, grade 80N/mm 2 concrete spun piles. The cooling water intakes consist of 1 No intake culvert type L and 1 No intake culvert type M units, which are each 9.5m long, 11.810m wide by 4.610m high. The triple cell pre-cast culvert units have interior barrel dimensions of 3.750m vertically and 3.450m horizontally, with 0.300m chamfers. Units L & M are the Side Units Left and Right. Units L & M are similar to the typical 10m pre-cast units. Unit L & M consists of one additional interior wall (over part of the 9.5m length), with two interior walls angled to direct flow. Leighton-LAMA Joint Venture

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Pre -cast Culvert Unit Type N

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End Unit 1 Type N

Units type N is the last pre -cast unit at the end of the intake culvert and it is installed in a dredged trench and is supported on 4 concrete pile caps which are supported on 4 No. 1m diameter, class C, grade 80N/mm2 concrete spun piles. There is only 1 No intake culvert type N, which is 9.5m long, 11.810m wide by 4.610m high. It is also a triple cell pre-cast culvert unit with interior barrel dimensions of 3.750m vertically and 3.450m horizontally, with 0.300m chamfers. Unit type N is similar to unit type F in tha t it has three access manhole openings in it, except that it has an end wall, which closes the unit off. Pre -cast Culvert Units Type P

Unit Adjacent to Transition Unit 1 Type P

Unit type P is the same as a typical unit type B and it is the unit that is situated adjacent to the transition unit type H. There is only 1 No intake culvert type P, which is 10m long, 11.810m wide by 4.610m high with the same interior barrel dimensions as all the other culverts. The pre-cast culverts units all have grout socks between each unit and they will form the joint seal between two consecutive units. Each pre-cast unit has a concrete housing structure on top of it, which contains the three dosing line pipes. 4.3. INTAKE TOWERS The intake tower structure is supported on the pre-cast unit types J (or K) by a monolithic in situ connection between the pre -cast elements i.e. unit J & K and the intake tower. There are 6 No intake towers, which consist of a concrete roof slab supported on 8 concrete columns. There is an opening all the way around which is closed off by a stainless steel grating. There is a diver access gate provided in the grating on one of the splayed corners of the intake tower. The intake towers are funnel-shaped structures which end in a 3.45m square opening in Intake Tower Structure the top of unit type J (or K). The hypochlorite dosing ring is attached to the intake tower structures. The intake towers are indicated in the photograph.

Access Grating

Leighton-LAMA Joint Venture

Dosing Line Ring

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4.4. DOSING LINES The dosing line pipes, which supply a hypochlorite solution to the cooling water intake culverts via the 6 intake towers, consists of three separate 225mm diameter, class 10, HDPE pipes which are continuously butt welded together in 12m lengths as indicated in the photograph below. 225mm diameter class 10 HDPE dosing line pipes Butt Welding Station

The dosing line pipes are approximately 1500m long with a dosing ring and nozzles distributed around the intake towers.

The chlorine dosing line pipes are housed in a small closed concrete cavity structure located on the top of the intake culverts. All three dosing line pipes are located within this housing, which comprises two sloping pre-cast concrete kerbs fixed to the top of the culvert, each with a recess at the top, into which a pre-cast concrete cover slab is positioned. The dosing line pipes will thus not be subject to significant wave forces, and will be protected from direct snagging dangers. The pipes were pulled out through HDPE sleeves that are cast into pre-cast concrete diaphragm walls, which are located at 5.0m c/c on the top of the pre-cast units. The housing and diaphragm walls are indicated in the photograph below.

Concrete Dosing Line Housing on top of pre-cast units.

Diaphragm Wall The dosing lines come ashore through the revetment. The 225mm diameter pipes are contained in a 355mm diameter class 10 HDPE sleeve above the in-situ culverts in the Leighton-LAMA Joint Venture

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revetment to protect the dosing lines from the backfill material and they end in a junction box where they will be connected to the pipe work from the chlorine dosing building. The onshore pipes and connection box is indicated in the photographs below. Dosing Line Land Section

255mm dosing line pipe

Junction Box

355mm sleeve

Dosing Line Junction Box

4.5. NAVIGATION STRUCTURE A south cardinal navigation structure marks the cooling water intake culvert. The navigation structure is situated approximately 50m south of the end pre-cast culvert type N at Latitude 4 008’30.93318” and Longitude 100 038’27.03496” with reference to the WGS 84 system. It consists of a structural steel tower structure, which supports the Tideland ML -300 Maxlumina Lantern. The tower is supported on a 1m thick concrete slab, which in turn is supported by 3 No. 900mm diameter raking pre-cast concrete spun piles. The concrete slab and equipment platform are fitted with steel handrails, access ladders and a small craft berthing fender structure. The structure is fitted with warning signs in English and Bahasa. The navigation structure is indicated in the photograph below.

Navigation Structure

South Cardinal Marker ML-300 Maxlumina Lantern

Lightning Conductor

Warning sign

Access Ladder and Fender

Leighton-LAMA Joint Venture

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4.6. PROJECT ORGANISATION AND RESOURCES 4.6.1.

Overall Organigram

Client TNBJ

Main Contractor ALSTOM-PEREMBA J.V.

Contractor ALSTOM

Sub Contractor – Civil Works Leighton Contractors (Malaysia) SDN BHD

Sub Contractor – Cooling Water Intake System Leighton - LAMA Joint Venture

Sub Contractor - Design and Engineering Consultant Murray & Roberts Engineering Solutions Ltd

Leighton-LAMA Joint Venture

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4.6.2.

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Murray & Roberts Engineering Solutions Organigram.

Project Leader Greig Wolfe

Engineering Manager Derek Paul (MRES)

Project Engineer Karl Heath (MRES)

Quality Assurance Mike Quarmby (MRES)

On - Site Design Co -Ordinator Alec Dixon (LLJV (MRES))

Project Design Team

Dra wing Office Rolf Aebischer (MRES)

CAD Operators • Nadeema Amlay • Guillame Du Toit • Adrian Julie • Theo Nel

In-house Design Engineers • Chris Michau • Hamied Mohammed • Stephan Hock • Pierre Botha • Simon Meyer • Richard Wegener

External Consultants • Ninham Shand • ZLH • Soil & Rock (Malaysia) • Terra Geotechnics (Malaysia) • Knight Hall Hendry

Document Controller • Cindy Feldman • Monica Mbusi

Leighton-LAMA Joint Venture

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4.6.3.

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Cooling Water Intake Leighton LAMA Joint Venture Site Management Team

Leighton -LAMA Joint Venture Exco

Project Manager Rick Moore (LLJV)

CWIC Construction Manager Rudi Voerman (LLJV (MRES))

General Superintendent George Salmon (LLJV)

Design Coordinator

Section Engineer Dosing Lines

Section Engineer Marine

Section Engineer Pre -Cast Yard

Alec Dixon (LLJV (MRES))

Francois Labuschagne (LLJV (MRES))

Barry Hofmeyr and later Dean Pearson (LLJV (MRES))

Dean Pearson (LLJV (MRES))

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SECTION 5. DESIGN OF THE COOLING WATER INTAKE 5.1. BACKGROUND TO THE DESIGN OF THE COOLING WATER INTAKE CULVERT The permanent and temporary works design were carried out by Murray & Roberts Engineering Solutions in Cape Town with some of the detailed design and analysis being carried out by external consultants. The purpose of the Cooling Water Intake System is to draw and deliver seawater from 1500m offshore to the power station cooling system on land at a flow of 88.2m³ per second. The proposed design concept was to use pre-cast reinforced concrete triple cell culverts, each having a dry mass of 400 tonnes. The culverts were to be pre-cast on land, transported offshore and placed on a stone foundation bed in a pre-dredged trench, then sealed underwater against the previous culvert unit using a filter fabric grout sock as indicated in figure 1 below.

Dredged Trench

Rock Armour

Stone Bed

Figure 1.

Sand Backfill

Proposed Design Concept

The cooling water intake culvert extends from a 56m-diameter cooling water pond onshore through the island revetment to the 6 intake tower structures 1500m offshore. The reinforced concrete culvert consists of a 68.5m long in-situ culvert, connecting into the 56m-diameter cooling water pond, 142 no. pre-cast culvert sections, 6 pre -cast intake tower structures, 3 x 225mm HDPE dosing lines on top of the culvert and a south cardinal piled navigation structure 50m south of the end of the last pre -cast culvert as indicated in figure 2 below.

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To optimise the culvert dimensions and minimise the head losses through the intake structures, a model of the proposed intake structure was constructed at the University of Stellenbosch in Cape Town, South Africa.

Navigation Structure

6 No. Pre-Cast Intake Structures

142 No. Pre -Cast Culverts

3 HDPE Dosing Lines

In-Situ Culvert Connection to the Cooling Water Pond

Figure 2.

Cooling Water Intake

To optimise the structural design, and minimize the mass, 3-D finite element structural analyses of the pre-cast culvert units were carried out, taking into account all the various load cases. The load cases modelled included the transportation of the units on heavy lift trailers to the load-out jetty, the lifting of the units off the load-out jetty using a specially designed 400 tonne floating gantry, the transportation of the units in the sea to its final position taking into account surge loads and wave loads. The intake tower structures were also modelled using 3-D finite element structural analyses. 1:50 and 1:20 models of the intake structures were constructed in the 1m wide wave flume at the University of Stellenbosch in order to measure the wave forces on the intake towers, to check overall stability and to optimise the design of the connection between the intake tower and the culvert. Two distinct soil layers were evident from the borehole logs. A 25m thick upper layer comprising highly plastic grey, silty clays and a 15m to 18m thick grey fine to coarse -grained sand layer below the grey, silty clay upper layer. The culvert was set below the seabed in a 1500m long dredged trench. During the dredging operation, however, it was found that a firm founding material on which to place the stone foundation bed could not be established. Probes by divers found firm material approximately 1m below the surface of the very soft clay. However, when the dredger removed this soft layer, it disturbed the firmer material below, preventing a firm founding layer from being established. Four additional boreholes with laboratory testing of core samples were carried out during January 2001 and it was found that the moisture content of the very soft clay was often greater than the liquid limit, causing the soil to liquefy during dredging. In order to reduce the risk of excessive differential settlements between the culverts, it was decided to change the foundation design. After a careful time, risk and cost evaluation, a Leighton-LAMA Joint Venture

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decision was taken to construct a piled foundation for the culvert units. The design change, due to the unforeseen founding conditions, occurred seven months after the start of the project. While a piling barge was sourced, the piled foundation design was carried out and all the approvals and testing requirements were put in place. As the pre -cast culvert construction was already well advanced the original structural design of the units had to be checked for the piled support condition. The first working pile was driven eight weeks after the decision to change the foundation design was taken. 28m long, 1m diameter, 80Mpa, hollow pre-stressed concrete piles were driven down to the bottom of the dredged trench with a follower to a specified level, to a tolerance of –50mm. Three to four piles were installed on site per day. Two piles were placed at each joint between the pre-cast culvert units. Pre-cast pile caps were constructed, then placed and grouted into the top of the hollow concrete piles as indicated in figure 3 below.

Pre -cast Culvert Unit

Intake Tower Structure

1000mm dia hollow prestressed concrete piles Pile Cap

Figure 3.

Piled Foundation

The 142 no culvert units, each with a mass of 400 tonne, were pre -cast on land under controlled conditions and transported by heavy lift trailers to a specially designed load-outjetty for placement offshore. The units were placed on the piled foundation by a specially designed 400 tonne capacity, floating gantry. Grout bags were then placed between the underside of the units and the top of the pile cap and pumped full of grout to take up any relative movement. This operation progressed extremely well and any time lost due to the change in design of the foundation was made up and e ven improved upon. The works were handed over within 15 months in October 2001 at a final cost of US$16 million. Leighton-LAMA Joint Venture

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The successful completion of this project required innovative engineering and the involvement of experienced marine personnel throughout all phases of the project. Design simulations, including physical and computer modelling, as well as on site testing formed a major part of the success of this design and construct project. Both the permanent and temporary works were designed by Murray & Roberts Engineering Solutions. The various elements required permanent works design and temporary works design were as follows: 5.2. PERMANENT WORKS 5.2.1.

Hydraulic Assessment of the Cooling Water Intake Culverts Professor Basson of the University of Stellenbosch wa s appointed to calculate the expected friction losses in the main culverts. Manning friction factors of 0,0116 and 0,0162 for "new and clean" and "old and fouled" roughness conditions respectively were used to calculate the total expected head losses. The head losses for "new and clean" conditions and "old and fouled" conditions were calculated to be about 1,6m and 2,6m respectively, both less than the specified corresponding maximum losses of 2,3m and 2,8m. Energy losses through the intakes into the culverts were difficult to quantify theoretically, due to the many changes in flow direction, and contraction and expansion of flow. It was therefore decided that a model study should be carried out in order to verify the design assumptions. In view of the complex geometry of the intake structure, it was decided to construct a 1 in 15 scale hydraulic model of one of the two sets of intakes discharging into the outer barrel culverts. The model was built and tested at the Hydraulics Laboratory of the Department of Civil Engineering of the University of Stellenbosch, South Africa, under the supervision of Professor GR Basson during November-December 2000. The total energy losses across two intakes and the bend was less than was predicted theoretically. The sq uare layout of the intakes with their relatively large throat areas therefore assisted in reducing losses. The maximum local velocities through the screen openings at Intake 1 under still water conditions was 0.49 m/s, which was less than the specified maximum velocity of 0,5 m/s. Velocities through a significant proportion of the screens at Intake 1 were lower and maximum velocities at all other intakes were also slightly lower. The model tests and results are fully described in Appendix D of the Report on the Hydraulic Assessment of the cooling water Intake Culverts Report No. MNJ/99/W/UPA/---/CA/06 rev 04. The model is indicated in the photograph below.

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Hydraulic Model of Intakes

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Assessment of the Wave Loading on Intake Towers The wave clima te for the design of the intake structures was determined, as recommended in Report No ZLH-554-02 Rev 01, November 2000, Manjung Power Station Project, Cooling water Intake Culverts and Jetty, Design Wave Conditions and Report No ZLH-554 -03 Rev 01, November 2000, Manjung Power Station Project, Wave Conditions for Calculation of Fatigue Loads for the Manjung Cold Water Intake Structures. Wave loads were computed using diffraction theory combined with Morrison drag forces where appropriate. Allowance was made for up to 50mm marine growth on the intake towers, when calculating the drag components of the forces. However, no information was available on the expected thickness of the marine growth. The wave and current loads on the structure were computed using WIFS (Wave Interaction with Fixed Structures), C J Garrison, 2000 and API RP2A, Recommended Practice for Planning, Designing and Constructing Fixed Offshore Platforms, Nineteenth Edition, 1991. Wave and current loads were computed for extreme conditions, as well as for fatigue design purposes. The theoretical hydrodynamic loads calculated for the design of the structures was compared with model tests that were carried out at scales of 1:20 and 1:50 for both broken and unbroken waves. The main purpose of the model study was to serve as a control on the numerical models that were used to calculate the forces and moments on the structure. The models were built and tested at the Hydraulics Laboratory of the Department of Civil Engineering of the University of Stellenbosch, to establish the wave induced moments on the intake structures. A comparison of the numerical wave force analysis results with those from the model tests resulted in the numerical results being used for design purposes, for the 6.3m design wave height. The model tests are described in the Appendix of design report no. MNJ/99/W/UPA/---/CA/021 rev 01. The model is indicated in the photograph below.

1:20 Wave Model Leighton-LAMA Joint Venture

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Structural Analysis and Design The reinforced concrete in the culverts had the following properties: • • • • •

45Mpa, 28 day characteristic strength Total cementitious content 485kg PFA content 30% of the total cementitious content Water/cement ratio 0.33 Reinforcement cover 60mm

5.2.3.1. In-situ Culverts The in-situ culvert consists of three sections of lengths 30m, 30m and 8.7m respectively. Movement joints are provided at the diaphragm wall and between the sections of the culvert, allowing full relative rotation across the joint. The joint design is described in document no. MNJ/99/W/UPA/---/CA 19.1. A reinforced concrete chimney, which provides access to all three barrels, is positioned towards the end of Section 1. This concrete chimney allowed temporary interior bulkheads to be installed into the in -situ culvert. The bulkheads were required to provide a dry interior when the water pool diaphragm wall was broken out to connect to the in-situ culverts. Reinforced concrete piles provide support to the culverts, positioned in four rows longitudinally under the culvert walls. The longitudinal pile spacing varies along the length of the in-situ culvert. No further detailed analysis or calculations were carried out for Section 2. Section 2 was detailed using the design carried out for Section 1 as the loads for Section 2 are the same as or less than Section 1. Reinforced concrete piles provide support to Section 3 of the Cooling Water Intake in -situ culvert. One row of 4 No. 400mm square pre-cast concrete piles, positioned longitudinally under the culvert walls, 1.5m from the movement joint between Section 2 and Section 3 and, 2 No. 700mm diameter concrete spun piles, under the internal walls of Section 3 of the in-situ culvert, at the joint between Section 3 of the in-situ culvert and the transition pre-cast unit. A continuous crosshead beam and 2 no. rectangular pile caps are cast over the 2 No. 700mm diameter concrete spun piles to support the pre-cast transition unit on. Finite elements analyses were carried out using LUSAS Ver 13, with pre and post processing using LUSAS Modeller Ver 13. The floor, walls and roof of the culvert were modeled to the mid-surface using 8 noded thick shell elements (QTS8 element type). The piles were modeled using engineering thick beam elements (type BMS3), with a single vertical spring element at the base of each pile to simulate the foundation stiffness. The interface between the piles and the culvert floor was modeled locally using 20 noded solid confinuum elements (type HX20), to simulate the load transfer from the beam elements (piles) to the shell elements (culvert floor). Ultimate Limit State (U.L.S.) structural design of the culvert section has been carried out using ultimate bending moments and shear forces extracted from contour plots for the worst load combinations.

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The Serviceability Limit State (S.L.S.) cracking checks have been carried out using the worst service bending moments, and a maximum permissible design crack width of 0,2mm. The design of Section 1 and 3 of the in-situ culvert is described in document no’s. MNJ/99/W/UPA/---/CA 04, Ca04.1 and CA 04.2. Figure 4.

In-situ Culvert Connection to Water Pool

Pre -Cast Concrete Units

Concrete Chimney Steel Bulkheads

1000mm dia Piles

Section 3

700mm dia Piles

Section 2

Section 1

400mm square Pre-Cast Concrete Piles

5.2.3.2. Pre -cast Culverts The pre-cast culvert section of the cooling water intake consists of approx. 142 No., 10m long, 11.810m wide by 4.610m high units supported on a concrete pile cap which is supported on 1m diameter, class C, grade 80N/mm 2 concrete spun piles. The triple cell pre-cast culverts have interior barrel dimensions of 3.750m vertically and 3.450m horizontally, with 0.300m chamfers.

Figure 5. Pre-cast Culvert Lusas Computer Model Leighton-LAMA Joint Venture

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The 10m long pre -cast culvert with three interior cells has been modeled using the LUSAS finite element software. The bottom slab, walls and top slab of the culvert unit was modeled to the mid-surface using 8-noded thick shell elements (QTS8 element type). The piles were modeled using beam elements (type BMS3) and the pile caps as 3-D solids (type HX20). The contact between the pile caps and the bottom slab thick shell elements was modeled using 3-D joint elements (type JNT4), in order to simulate the contact over the correct area on the pile caps. Axial joint elements (type JSH4) were used at the bottom of the piles to simulate the long term loadsettlement behavior of the piles. The computer model is indicated in Figure 5. The position of the piles and pile caps relative to the culvert unit was varied. In each case the pile cap joint elements were revised such that the contact area was correctly approximated. Full fixity boundary conditions were applied to the bottom of the piles. All nodes on the piles were given horizontal spring stiffnesses in the two global horizontal directions, based on the horizontal coefficient of subgrade reaction determined by Soil & Rock Engineering for the 1,0m diameter spun concrete piles. The magnitude of the spring stiffnesses used for the lateral soil restraint was increased until the horizontal deflection of the piles was approximately the same as that obtained by Soil & Rock Engineering in the full geotechnical analysis. The detailed geotechnical and structural design calculations for the piled foundation are contained in: • • • •

Design report No. MNJ/99/W/UPA/---/CA/24 Design report No. MNJ/99/W/UPA/---/CA/24.1 Design report No. MNJ/99/W/UPA/---/CA/24.2 Design report No. MNJ/99/W/UPA/---/CA/25.

5.2.3.3. Intake Structures The cooling water intakes consist of 6 intake culvert units, which have internal walls for diverting and channeling the water flow and intake tower structures which are fixed in-situ to the top of the culvert units which are supported on 8 concrete pile caps on 8 No. 1m diameter, class C, grade 80N/mm² concrete spun piles. The layout of the intakes is indicated in figure 6. The pre -cast culvert units supporting the intake towers were constructed onshore on a number of prepared casting beds. The units were cast on plinths in an elevated position to allow the heavy-lift trailers to move in underneath the units in order to lift and load the units. Each unit’s dry weight was approximately 400t. The culverts were then transported by heavy-lift trailers onto a specially constructed temporary load-out jetty. This allowed a floating gantry to straddle the jetty and unit, to lift it off to transport it out to a temporary stone foundation bed offshore The intake tower structures were constructed onshore on a number of prepared casting beds. The intake tower structures were cast separately from the intake culvert units supporting them. Each intake tower’s dry weight was approximately 156t. The heavy-lift trailers then transported the intake tower structures onto the specially constructed temporary load-out jetty. The floating gantry then straddled the jetty and intake tower, and Leighton-LAMA Joint Venture

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lifted it off for transport out to the culvert unit, which had already been placed on the temporary stone foundation bed offshore. The intake tower structures were then fixed to the submerged culvert units by means of an in-situ concrete connection at low tide. The floating gantry then moved the completed intake culvert units including the intake towers to their final positions on the piled foundations. The intake units on which the towers are supported were analysed as per the typical pre-cast units using the LUSAS finite element software. The intake tower structure was also modeled using the LUSAS finite element software. All components of the structure were modeled to the midsurface using 8 noded thick shell elements (QTS8 element type). The tower model was provided with a continuous support at the bottom, with fixity in all global axis directions to model the connectivity to the pre-cast unit. The wave pressures on each component of the structure were calculated using the maximum resultant horizontal and vertical loads on the structure as determined from the model tests and numerical analyses carried out using MORA. This previous study determined that the worst extreme wave conditions anticipated will be unbroken waves (Waves on point of breaking) with Hmax = 6.0m and a period of 8 seconds. A typical contour plot from the Lusas software is indicated in figure 7. The detailed geotechnical and structural design calculations for the intake structures are contained in Design report No. MNJ/99/W/UPA/--/CA/25.1..

Figure 6.

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Layout of Pre-Cast Intake Towers

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Figure 7.

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Lusas FE Model Contour Plot of Pre -Cast Intake

5.2.3.4. Navigation Structure The Navigation Light Structure has been modeled as a space frame on Staad Pro 2001, using shell elements to model the pile caps and the piles were modeled as 900 mm diameter x 130 mm thick concrete beam elements. The horizontal loads on the piles are applied as trapezoidal beam loads and the horizontal loads on the slab are applied through a special dummy beam element at the slab perimeter. Horizontal spring supports were calculated to simulate fixity of the structure. Lateral soil springs were provided at different depths along the length of the piles, which were based on a lateral modulus of subgrade reaction as determined by Soil & Rock Engineering. Vessel berthing loads were calculated based on the recommendations of BS 6349 : Part 4 : 1994 Section 4.7. A berthing velocity of 0.5 m/sec was used in the calculations. An EXCEL spreadsheet was developed for determining the wave particle velocities and wave forces based on Linear Airy wave theory using Morisons equation. The detailed geotechnical and structural design calculations for the navigation structure are contained in Design repo rt No. MNJ/99/W/UPA/--/CA/03. The navigation structure is indicated in the photograph below.

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Geotechnical Analysis of the Piled Foundations The PIES computer program was used to estimate the geotechnical safe working loads for the concrete piles which support the in -situ, pre -cast and intake structure culverts. The PIES software was developed by Professor Poulos at the University of Sydney. The software uses a simplified boundary element formulation and models the interface between the pile and soil in a hyperbolic manner. The programme calculates the down drag load of a pile embedded in settling marine clays and the pile head settlement for different applied pile head loads. In this way, a complete load vs settlement curve was derived. The safe working load of the piles was also calculated using theoretical models provided by Professors Fleming and Randolph. The safe working loads (geotechnical) of the concrete piles were calculated for different pile penetrations. These static analyses were carried out using the computer program PILER. Soil and Rock Engineering, Geotechnical Consultants in Kuala Lumpur, carried out the PIES and PILER analyses referred to above. Soil & Rock Engineering evaluated horizontal spring stiffnesses in the two global horizontal directions at all the nodes on the piles. These horizontal spring stiffnesses where based on the horizontal coefficient of subgrade reaction of the soil profile. These spring stiffnesses were used in the structural analyses.

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Hydraulic, Installation and Design of the Dosing Lines 5.2.5.1. Hydraulic Design. The hydraulic assessment for the dosing lines for the cooling water intake culverts from the skid to the intake was modelled with the nozzles, without any backpressure or non-return valve. The design parameters were as follows: Maximum flow in pipes 186 m3/hr per pipe, Nominal flow 62 m3/hr, Minimum flow (one pump) 10 m3/hr, Head from pump curve for 51,66 l/s = 28.4m, Head loss on shore to battery limit (Max flow) = 6.7m, Elevation of pumps (above sea level) = 4.15m. We did not have information of the actual pump curves, and we assumed that the losses of -6.7m in the pipe work and control valves were correct for the high flow condition. We used the PIPEN software to analyse the dosing line system. Wave action will create a dynamic affect in the system, this may influence the short term dosing at the individual intakes, but the general level of chlorination in the line should not be affected. The output from the PIPEN analysis software for the various runs are contained in design report No. MNJ/99/W/UPA/---/CA/05. The analysis was based on a 140 ∅ dosing ring pipe, but this was subsequently changed to a 160 ∅ dosing ring pipe as this size was more readily available than the 140 ∅ pipe. Please note that there is not a significant difference in the analysis between the 140 ∅ and 160 ∅ pipe for the dosing ring line as most of the losses occur in the main 225 mm ∅ line. Wave action will create a dynamic effect in the system, this may influence the short term dosing at the individual intakes, but the general level of chlorination in the line should not be affected. 5.2.5.2. Installation Design The pipes were pulled out through HDPE sleeves that were cast into concrete diaphragm walls located at 5.0m c/c on the top of the pre-cast units. The pipes are located in a closed cavity (covered with concrete cover slabs), and were thus not subject to significant wave forces, and will also be protected from direct snagging dangers. The pipes were assembled on land in lengths of 24m and then joined before being pulled out by a suitable barge or vessel, through the sleeves. There were three different pulling lengths i.e. 1315m, 1375m and 1435m. The pipe was designed to overcome the following forces during installation (pulling): inertia, friction at sleeves from buoyancy, affects of mis-alignment of the sleeves from placing tolerances in the pre -cast units or settlements and launching friction on the land rollers. A pulling nose was designed and attached to the front of each pipe. An opening was provided in the pulling nose to allow water to enter the pipe to flood it as it was being launched.

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The calculation of the installation forces and the pipe stresses in the HDPE PE80 225 ∅ Class PN 10 dosing line pipe are contained in design report no. MNJ/99/W/UPA/---/CA/05.1 5.2.5.3. Pre -cast concrete housing design The chlorine dosing lines are housed in a small concrete structure located on the top of the intake culverts. All three dosing lines are located within this housing, which comprises two sloping kerbs fixed to the top of the culvert, each with a recess at the top, into which a pre-cast cover slab is positioned. These pre-cast concrete housings are subject to various forces, the most significant of these forces is uplift on the slabs and drag forces on the kerbs, due to the action of waves and current.

A model test is the most reliable method to obtain the forces and uplift on the units, but time and cost constraints prevented this. The analytical methods used to calculate the design uplift on the top of the culverts was therefore an approximation The analytical calculations were based on the best estimates for the combined effects of a depth limited wave for 10m of seawater over the culvert and an allowance for up to 2m scour next to the culvert, together with the design current of 1.0 m/sec. Linear wave theory was used to estimate the wave induced water velocities in the region of the housing units. Drag and lift pressures were calculated using Morison’s equation. The resulting pressures with 2% included for added mass were calculated as 35 KPa Lift and 17.7 kPa Drag. The lift force was applied to the top of the pre -cast element, and the drag forces have been applied as 79% to the front kerb as a pressure, and the remaining 21% to the back kerb as a suction force. Bolts were recommended to hold down the pre-cast concrete covers but the JV chose not to use holding down bolts. The calculations for the pre cast concrete housing are contained in design report no. MNJ/99/W/UPA/--/CA/05.2

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5.3. TEMPORARY WORKS The temporary works elements requiring detailed design were as follows: 5.3.1.

Load Out Jetty A reinforced concrete jetty, supported on concrete spun piles, was designed to provide a structure over the water where the pre -cast units could be positioned and lifted off the jetty using a floating gantry, before being towed to the dredged trench and lowered onto the foundation bed in their final position. The full jetty was mode led using an assemblage of beam elements and analysed using the PROKON software package. The pre -cast deck slabs were modeled using beam elements, with each beam having a width equal to half the width of a pre-cast slab panel.

Horizontal supports for the piles were provided at -4.40m ACD, which corresponds to a point about 2,5 pile diameters below the scoured seabed level. A scour of 1,0m was taken into account. At the pile toe (taken at – 14,40m ACD) horizontal supports were provided, as well as a vertical spring with a stiffness of 70 000kN/m, which corresponds to the lower bound pile spring stiffness as calculated by Soil & Rock Engineering. Towards the rear of the jetty the horizontal restraints were positioned higher up the pile to take account of the sloping landfill embankment and revetment. The detailed structural design was carried out in accordance with BS6349, BS5400 and BS8110. Bending moment and shear force envelopes at Ultimate Limit State were extracted from the PROKON analysis, for the primary elements of the structure, namely the pre -cast deck slabs, the longitudinal deck beams near the end of the jetty, the crosshead beams and the piles. Reinforced concrete design calculations based on the formulae in BS8110 were carried out for the peak forces on each primary element, using spreadsheet calculations. These were supplemented with additional hand calculations where necessary. Spreadsheet calculations were used to check the Serviceability Limit State crack widths, based on the crack width formulae in BS5400.

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The calculations for the load out jetty are contained in design report no. MNJ/99/W/UPA/---/CA/02. Lateral load analyses for the concrete spun piles were carried out using the geotechnical software, DEFPIG 6XB (1999), which was developed by Professor Poulos at the University of Sydney. The programme analyses the behaviour of single piles and pile groups when subjected to axial and horizontal forces and moments. The piles were divided into 50 elements and limiting pile- soil stresses (ultimate skin friction values) and elastic moduli were assigned to each element. The pile head reactions determined from PROKON software were applied to the 700mm spun piles and lateral deflections and bending moments were calculated for single piles driven through the revetment and offshore. The lateral deflection at the pile head level ranged from < 2mm to about 10mm. The maximum bending moments ranged from about 30kNm to 150kNm. The effects of a 2 No x 760kN berthing force on the 39 piles supporting the load out jetty was modelled using DEFPIG. The maximum lateral deflection at pile head level was estimated to be 14mm and the maximum bending moment was estimated to be 1860kNm. The calculations for the loadout jetty are contained in design report No. MNJ/99/W/UPA/---CA/02.1. 5.3.2.

Cofferdam A 53.2m long by 14.4m wide cofferdam was required in order to construct in-situ section of the concrete culvert for the connection of the cooling water intakes to the cooling water pond. The cofferdam was a multi-propped type with three layers of props at +1.50m, -2.70m. and –5.50m ACD respectively. The excavation depth inside the cofferdam was approximately –8.00m ACD. The ground surface of the existing island was about +4,65m ACD. The ground level for a distance of approximately 8m around the cofferdam was reduced to a level of +3m ACD to reduce the soil loads on the sheet piles. A second row of Lx 16 sheet piles was driven around the cofferdam and the water table inside this area was reduced to approximately 0.0m ACD, in order to reduce the water pressure on the cofferdam. Boreholes were drilled, SPT’s, hand shear vane tests, and later CPT’s were carried out to determine the properties of the soil in the area to enable an analysis of the cofferdam to take place. The ground conditions varied significantly over the Cofferdam area. The cofferdam was therefore divided into 3 distinct sections for design, referred to as Sections 1, 2 and 3 respectively. Section 1 – Onshore - from 20m to 33m from the Diaphragm Wall, Section 2 - Revetment - from 33m to 52.2m from the Diaphragm Wall (Section 2a - from 33m to 42m, Section 2b – from 42m to 52.2m), Section 3 – Offshore from 52.2m to 73.2m from the Diaphragm Wall. The ground conditions for Section 1 (Onshore) were better than for Section 2 (Revetment) and Section 3 (Offshore) as they were surcharged by the reclamation. The 3 Sections of the cofferdam consisted of 4 different types of sheet pile sections. Section 1 (Onshore) - 13m of 18m long PU25 sheet piles driven to –15m ACD, Section 2 (Revetment) - Section 2a - 9m of 24m long PU25 sheet piles driven to –21.0m ACD plus Section 2b - 10.2m of 24m long reinforced PU25 sheet piles driven to –21.0m ACD, Section 3 (Offshore) - 21m of 24m long reinforced Lx 32 (or equivalent 24m long reinforced PU 25) sheet piles driven to –21.0m ACD.

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The WALLAP and PLAXIS finite element computer programs were used to perform the stage-by-stage analyses of the structure, in order to determine the stability of the cofferdam, the waler loads and the bending moments and shear forces in the sheet-piles, during the construction process. The programs can be used to model a braced excavation in layered soil deposits. PLAXIS is a finite element program that is capable of analysing excavation problems in 2-dimensional continuum under plain strain conditions. A 6-node isoparametric element was used to model the soil medium. Underneath the firm clay layer was the sand stratum and a fixed base was assumed. The phreatic line was assumed to be at +1.0m ACD. Beam elements were used to model the wall and struts. The problem was symmetrical and therefore only half of the cross section was analysed. The sequence of construction involving the excavation of a soil layer, the installation of sheet piles and struts, and ground dewatering can readily be modeled by the programs. The construction sequence generally consisted of: i) Installing concrete piles for the culvert foundation, ii) Installing sheet piling to toe elevations of -15m and –21m ACD, iii) Excavation for the cofferdam, iv) Installing the three layers of struts and walers and de-watering as the excavation proceeded, v) Casting the in-situ culvert base slab hard up against the sheet piles and vi) Removing layer 3 of the struts and walers, vii) Completing the in-situ culvert construction and, viii) Removing layers 2 and 1 of the struts and walers as the backfilling proceeded. WALLAP carries out two (2) separate types of analysis: i) Limit equilibrium analysis where factors of safety are calculated in accordance with recognised and codified procedures; and ii) Bending moment and displacement analysis. This is carried out Leighton-LAMA Joint Venture

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by modeling the stage -by-stage development of forces and wall movements as excavation proceeds. The results of the WALLAP analyses were not included in the report as they were only used as a design check. The client would also not accept designs carried out using WALLAP. • • • 5.3.3.

The calculations for the cofferdam are contained in design report no. MNJ/99/W/UPA/---/CA/13.2. Tied back cantilever sheet pile walls were designed at the end of the cofferdam to enable the placing of the first pre-cast unit next to the in-situ culvert. The calculations for the wing walls are contained in design re port no. MNJ/99/W/UPA/---/CA/13.3

400 tonne Floating Gantry The floating gantry was a space frame structure consisting primarily of Grade 43A steel (or equivalent) tubular members. The structure spanned between two 120’ x 40’ x 8’ barges in order to stra ddle the load out jetty on which the culvert unit was placed. The function of the gantry was to lift the unit at two lift points on the gantry structure and transport the unit while hanging from the gantry to the offshore location where the unit was lowered into its final position in a pre-dredged trench. The gantry was towed out from the load out jetty to the final placement location. The geometric configuration was determined by the following factors : Clearance over the culvert unit placed on the loadout jetty, Barge dimensions and locations of bulkheads for gantry support placement, Tidal ranges relative to jetty levels, Culvert unit dimensions and lifting corbel locations and the Space provision for rigging and lifting equipment.

Leighton-LAMA Joint Venture

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In order to assist the structural efficiency of the system, two tie members were included at a level around 5.5m above the deck of the barge in order to prevent the separation action of the two barges while the unit is hanging from the gantry. This meant that the relative outward displacement of the barges was not only resisted by the portal framing of the gantry. The tie members needed to be placed after the gantry was moved over the unit prior to lifting due to clearance considerations. The structural analysis of the framing was performed using STAAD – Pro 2000 finite element analysis software. Simple beam elements were used for member modeling with tubular section properties. Member offsets at the tubular connections were included in the model with additional members around the intersection points. The overall geometry and more specifically the tubular intersection geometry were developed with the assistance of a 3-D CAD model assembled with AutoCAD software. Offset geometry coordinates were then imported as input for the STAAD model. The 3-D model was also used for rigging and sheave block clearance checks especially around the lift point node. Boundary conditions were applied at the bases of the four legs on each side of the gantry (4 x 2 = 8 locations). The barge was not included in this structural model. Vertical springs with stiffnesses representing the barge buoyancy were used at all 8 locations. One side of the gantry base was released in the horizontal plane in order to accommodate the outward relative displacement of the barges. The following loadings were considered for the structural analysis: • • • • •

Dead Load : Applied as a uniformly distributed load throughout the structure self-generated by the STAAD software. This was factored up by 5% to include appurtenances like walkways and ladders. Live Load : Hanging weight of the concrete culvert unit together with associated rigging. This hanging load was applied as a point load at the lift point node. The load factor used is explained below. Environmental Loads : The environmental data used for adopting a design wave is contained in the design report. Wind : the magnitude of the wind loading on the gantry is insignificant compared to the other loadings and hence was ignored. Wave and Current : The 10 year return period maximum wave height is between 0.75 and 1.0m and hence a 1m wave height was used for the design together with 0.5m (1 knot) current. The effect of the wave and current on the barges was calculated and applied to the base of the gantry legs to represent transfer of environmental load into the gantry via the barge.

By far the most critical load condition was the case of the unit hanging prior to submergence in the water (i.e. the dry weight of the unit). For wave loading effects on the barges the following wave directions have been considered : Beam wave (across the two barges) in order to model the effect of barge separation in addition to differential heave and Quartering (diagonal) wave to model the torsional loading effects on the gantry due to anti-symmetric rotation of the barges about the transverse gantry axis. The STAAD program has an API code check facility and this was used for member design. In addition, the API punching shear requirements are included in the API code check. Hence the tubular connection design is also part of the STAAD structural analysis.

Leighton-LAMA Joint Venture

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The lift point, tie member connection to the 500 mm diameter gantry legs and barge support grillage were designed in accordance with the AISC steel design code. In order to lift the unit from the load out jetty from two lift points on the gantry to four lift locations on the typical culvert unit, a spreader beam was required to spread the lift load from a single line to the two lifting corbels on each side of the unit. The unit was lifted b y Macalloy bars attached to the culvert corbels. The bars were attached to the lift beam which was connected to the lower sheave block by slings. The calculations for the floating gantry are contained in design report no. MNJ/99/W/UPA/---/CA/13.3 5.4. EXTERNAL CONSULTANTS The following external consultants were appointed to carry out the following detailed design and analysis.

Ref.

Design Element

Designer

1.

Structural Analysis and Reinforcement Design of In-situ culverts, Pre-cast culverts and Intake Tower Structures

2.

Computer Modelling of Wave Forces on the Intake Towers

3.

Dosing Line Hydraulic Analysis and Structural Design

4.

Geotechnical Design of the piled foundations

5.

Geotechnical Analysis of Cofferdam

6.

Hydraulic Analysis and Head Loss Calculations

Ninham Shand

7.

Physical Hydraulic Model of the Intake Towers

8.

Physical Wave Model of the Intake Towers

University of Stellenbosch

Leighton-LAMA Joint Venture

Zietsman Lloyd and Hemsted Inc.

Soil & Rock Engineering

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SECTION 6. GEOTECHNICAL CONDITIONS ENCOUNTERED ON THE CULVERT ROUTE 6.1. GEOTECHNICAL INVESTIGATIONS The initial geotechnical data was obtained during the offshore site investigations, which were carried out by Strata Drill Sdn. Bhd. on behalf of Alstom Export Sdn. Bhd. during December 1999 and January 2000. The site investigation information, which was provided by the client at tender stage, included the following: •

• •

Six, 50m deep, exploratory boreholes drilled using rotary washboring with SPT testing and undisturbed Shelby tube sampling. Three boreholes (103, 104 and 105) were drilled along the intake route. In-situ, field vane testing was undertaken at 1,5m to 2m intervals in the boreholes until refusal. Laboratory testing of undisturbed samples from the boreholes, included Atterberg limits, particle size distribution, UU and CU triaxial compression tests, oedometer, natural moisture content and chemical testing. Twenty-five, 20m deep, marine piezocone penetration tests (CPT) were undertaken to measure cone resistance, sleeve friction and porewater pressure. Dissipation tests were also conducted. Fifteen of the CPT tests (CPT110 to CPT 124) were undertaken along the intake route.

6.2. THE SOIL PROFILE The intake route is underlain by more than 50m of unconsolidated sediments, which are described, in part, in the borehole logs as alluvium. However, references in the borehole logs to shells suggest that, at least, the upper parts of the sedimentary layers have a marine origin or a reworked marine origin. Two distinct soil layers were evident from the borehole logs. The upper 25m comprising grey, silty clays with minor sandy clays. Sandy or silty lenses, shell fragments and traces of organic material and decomposed wood also occur. Grey to light grey, lenses of slightly silty, fine to coarse sand with some angular to sub rounded, fine to medium quartz gravel was recorded, in places. The thickness of these occurrences ranges up to 1,5m. These clayey soils were highly plastic, with the natural moisture content of the upper 4m of soil approaching, but not exceeding ht e liquid limit. The undrained cohesion varied from 5kPa to 13kPa at seabed level with a typical increase of 1.25kPa/m depth. A sandy layer that generally ranges in thickness from 15m to 18m occurs approximately 25m below sea floor (about -30m to -35m CD). These light grey sands are fine to coarse grained and frequently contain sub angular sub rounded, fine to medium gravel. In places, the sands are silty, and thin silty and clayey layers also occur. 6.3. GEOTECHNICAL CONDITIONS ENCOUNTERED DURING DREDGING During November 2000, whilst trimming the excavated trench in the seabed to final level, diving inspections showed that a layer of between 500mm and 2.0m of soft disturbed material continuously remained in the bottom of the trench. After removal of further material to reach the firmer underlying layers identified by diver probes, the thickness of this layer of poor material did not diminish but remained fairly constant. Leighton-LAMA Joint Venture

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As a result the crushed stone foundation bed could not be placed in accordance with the original design requirements and there was concern about being able to develop the required 10 kPa bearing capacity. It was initially unclear as to the source of the poor material as it could not be identified in the soils data supplied at tender stage. The possibility was that it flowed in from the surrounding seabed or that it arose from the disturbance of the seabed materials during the dredging operations. It is now generally accepted that the material which was marginal as a founding layer tended to liquefy when disturbed by the dredging operations. 6.4. REVISED COOLING WATER INTAKE FOUNDATION DESIGN The LLJV requested the designers (LAMA) to investigate the cause of the problem and revise the design to accommodate the seabed materials encountered. At the beginning of December 2000 LAMA personnel travelled to the site to meet with the LLJV site personnel and local Malaysian geotechnical engineers. The purpose of this visit was to discuss and to determine the cause of the problem, and if necessary to institute remedial actions or alternative designs. Samples of the excavated material were viewed and tested, and the available borehole cores were investigated. A specification was issued for further borehole drilling along the trench alignment and four additional exploratory boreholes were drilled during December 2000 to supplement the investigations conducted by Strata Drill Sdn. Bhd. Meetings were held in Malaysia with local geotechnical consultants, the Client, Powergen and the LLJV site personnel to discuss and agree on an alternative foundation design which would allow construction to continue with as little delay as possible. As a solution it was proposed that instead of attempting to remove the poor material, large sized graded rock fill would be dumped in order that it would penetrate the soft underlying material and form a base for the stone bed. A drop test was carried out to ascertain to what depth a rock would sink to in the deleterious material. A granite rock (approximate dimensions 0.3m x 0.5m) supported on a graduated tape was dropped into the soft material. It sank to a depth of about 1.5m. Hand probing at this location refused at a depth of about 2m. LAMA prepared an initial report on their findings and the proposed revised design. In order to verify the proposed design, a finite element model was set up using the Sage Crisp finite element software to calculate and predict the long -term settlement of this foundation proposal. Rock dumping commenced on site to the revised design in order to carry out insitu testing. The intention was to place a culvert unit on a foundation constructed to the revised design in order that the actual short-term settlement could be measured and used to calibrate the FE model. This would improve the accuracy of the model’s long-term settlement predictions. The results of both the model and the prototype gave very encouraging and acceptable levels of settlement. The relevant drawings were changed and design reports prepared for the revised foundation deta ils. At the February 2001 JV Exco meeting, the decision was taken to rather consider using a piled foundation than the dumped rock solution that had been proposed. The reason for this selection was that it was felt that there was less risk of differential settlement between culvert units in the long -term with a piled structure and that Alstom were in favour of this change. All work on the rockfill alternative was then stopped and the test unit removed from the seabed. 6.5. CONCLUSIONS The problems encountered with the seabed materials in the trench were considered by LAMA to be unforeseen ground conditions, as the soil investigation information provided to

Leighton-LAMA Joint Venture

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LAMA at the time of the final design being carried out did not indicate that these materials would behave in this way during dredging. This view has been well documented in the report submitted for the revised design, as well as in reports by independent geotechnical consultants. The original design was found to be acceptable to our appointed local (Malaysian) geotechnical consultants, the Clients geotechnical engineer, as well as Powergen’s Chief Engineer. At no stage during the design and design approval process (which was by then largely complete) did anyone, including the local engineers involved, foresee problems with this material. 6.6. RELATED DOCUMENTS ISSUED Design Reports: • • • • •

Doc. No. MNJ/99/W/UPA/---/CA/16, Interpretation of Geotechnical Data For The Cooling Water Intake Culverts, Rev 03, 16/11/00. Doc. No. MNJ/99/W/UPA/---/CA/22, Report on Unforseen Ground Conditions Resulting in the Redesign of the Dredge Pocket Between CH300m and 500m, Rev 02, 15/01/01. Doc. No. MNJ/99/W/UPA/---/CA/16.1, Revised Geotechnical Design Report – For Foundation Type B, Rev 03, 06/02/01. Doc. No. MNJ/99/W/UPA/---/CA/30, SRK Consulting Review of Existing Geotechnical Data for the Cooling Water Intake Culvert, Rev 01, 13/02/01. Knight Hall Hendry report – Review of Geotechnical Data ref LAMA01C\RWH\ms dated 6th March 2001

Leighton-LAMA Joint Venture

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SECTION 7. PRODUCTION RATES, PLANT UTILIZATION AND CREW SIZES 7.1. OVERALL PRODUCTION

Cooling Water Intake Graphical Overview of Schedule of Work

160

9 August 2001 Alstom handover Grid 23 to Grid 142

140

GANTRY MANUFACTURE

120

STONE SPREADER

Substantial Completion Inspection requested 5 September 2001 from Alstom

CLAMSHELL DREDGE SPREAD

AVE CEASAR DIPPER DREDGER 100

PILING OPERATIONS NAV STRUCTURE 80

PRECAST WORKS

UNIT PLACING

40

08/10/2001

08/09/2001

08/08/2001

08/06/2001

08/05/2001

08/04/2001

08/02/2001

08/01/2001

08/12/2000

08/11/2000

08/10/2000

08/09/2000

08/08/2000

08/07/2000

Leighton-LAMA Joint Venture

08/03/2001

17 April First unit placed

Establish PC Yard

20

0

DOSING LINE

Cofferdams, Insitu cilvert (Phase 1 ,2 &3)

60

08/07/2001

No of units and interface

JETTY

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End of Contract Report – Volume 1

7.2. CULVERT UNIT PLACING

Manjung Power Station : Cooling Water Intake Culvert Unit Placing Graph 160 Gantry Damaged on 25 June 2001 : 1 week delay

140

120

100

Units from No 23 to furthest offshore unit 142

Note : no units placed due to Phase 3 cofferdam not being ready, piling able to proceed until cofferdam completed

Final Unit Placed 28 August

INSHORE UNITS no 22 to transition

80

60

First Unit No 23 Placed 17 April 2001 at Chainage 296m

40

20

142 NO. UNITS TO BE PLACED All placed in 83 calender days

0

Leighton-LAMA Joint Venture

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7.3. PRE-CAST CULVERT CONCRETE PRODUCTION

Manjung Power Station Cooling Water Intake Cumulative Precast Culvert Concrete 30000

25000

20000

15000

142 no CULVERTS 1 no Culvert = 164 cubic metres Produced 1 no culvert per day Concrete supply by Boom Pump Target Daily Base pour 64 cubic metres start 11 am Wall & Roof pour 115 Cubic metres by 13H00 Base Pour : normally 2 to 3 hours Wall & Roof Pour : 4 to 5 hours

Chinese New Year Christmas/New Year

10000

5000

0

Leighton-LAMA Joint Venture

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7.4. PRE-CAST CULVERT MANUFACTURE

Manjung Power Station : Cooling Water Intake Precast Culvert Manufacture

160 TYPICAL WEEK 1 culvert per day 140

6 days per week No night shift Extended hours and Sunday preparations only

120

No of Culverts

139 UNITS COMPLETE

FIRST UNIT PLACED OFFSHORE AT GRID LINE 23

100

80

Planned 5 October 2001

ALL SPECIAL UNITS constructed towards the end of the works

HEAVY LIFT TRAILERS ON SITE

60

40

UNITS IN TEMPORARY STORAGE

18/05/2001

11/05/2001

04/05/2001

27/04/2001

20/04/2001

13/04/2001

06/04/2001

30/03/2001

23/03/2001

16/03/2001

09/03/2001

02/03/2001

23/02/2001

16/02/2001

09/02/2001

02/02/2001

26/01/2001

19/01/2001

12/01/2001

05/01/2001

29/12/2000

22/12/2000

15/12/2000

08/12/2000

01/12/2000

24/11/2000

17/11/2000

10/11/2000

03/11/2000

27/10/2000

20/10/2000

13/10/2000

06/10/2000

29/09/2000

0

22/09/2000

20

Blue line = Manufacture Red line = Placing

Leighton-LAMA Joint Venture

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7.5. COOLING WATER INTAKE M AJOR QUANTITIES Concrete Quantities Pre -cast Culverts In-situ Culverts Stools Pile Caps Load-out Jetty Establishment Intake Beds PC Beds

23 500 1 195 576 556 420 370 360 343 27 320 m3

Reinforcing Quantities Pre -cast Culverts In-situ Culverts Stools Pile Caps Load-out Jetty Establishment Intake Beds PC Beds

2 675 130 52 153 79 0 65 22 3 175 Ton

Formwork Quantities Pre -cast Yard Load-out Jetty In-situ Culvert

80 885 1 313 4 170 86 368 m2

Square and Round Piling Quantities 700mm diameter x 42m long Pre-stressed Spun Concrete Piles for Load-out Jetty 700mm diameter x 30m long Pre-stressed Spun Concrete Piles for In-situ Culvert

40 No

400 x 400mm x 36m avg. length Square Pre -cast Concrete Piles for In-situ Culvert support

72 No

1000mm diameter x avg. 28m length Pre -stressed Spun Concrete Piles for Main Culvert Foundation

320 No

Leighton-LAMA Joint Venture

2 No

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7.6. MARINE WORKS PRODUCTION

Manjung Power Station : Cooling Water Intake Piling - Pile caps - Culverts 350 300 250 200 150 100 50 0

17- 24- 3107- 14Mar- Mar- Mar- Apr- Apr01 01 01 01 01

2128- 05- 1219- 26- 0209- 16- 2330Apr- Apr- May- May- May- May- Jun- Jun- Jun- Jun- Jun01 01 01 01 01 01 01 01 01 01 01

07Jul01

14Jul01

21Jul01

28- 0411- 18- 2528Jul- Aug- Aug- Aug- Aug- Aug01 01 01 01 01 01

Piling

0

0

1

12

30

54

78

98

122

138

162

182

206

222

246

264

276

280

280

288

288

288

312

Pile Caps

0

0

0

0

0

12

36

60

80

104

120

144

164

188

204

228

252

264

276

280

288

288

290

312

Units

0

0

0

0

0

3

9

14

20

28

40

50

62

70

82

94

106

114

116

118

125

125

125

140

Leighton-LAMA Joint Venture

142

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SECTION 8. COST VS BUDGET 8.1. PROJECT COST OVERVIE W

Project Cost Breakdown Dosing 4% Design 6%

PC

Profit 11%

Marine C'Dam

Precast 24%

LOJ Staff P&G Design Dosing Profit

P&G 2% Staff 10% Load Out Jetty 1%

Marine 35% Cofferdam7 %

Leighton-LAMA Joint Venture

Approximate Total RM 53 200 000

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8.2. STAFFING COST

Total Estimated Cost RM 5,282,595

2% 4% 25%

2%

67%

Expat Local Accom Vehicles Mob/Demob

Staffing Cost Proportions (Malaysia 2000/2001) 8.3. FINANCIAL (SEE SECTION 18 FOR DETAILS) Although the costs of the work increased considerably due to the change in the foundations for the culvert, the project still generated 80% of the projected profit (excluding the insurance payout on the foundation design.) With the insurance payout taken into account the profit generated was about 35% above the tendered profit. 8.4. ASSET MANAGEMENT All assets purchased by the joint venture during the course of the project are recorded on an Asset Register. Toward the end of the project many assets are no longer required and is usually disposed of. Major assets include used Sheet Piles, hydraulic hoisting and mooring winches, various power tools and small plant items, unused materials and equipment, containers and office equipment. Suggestions for improvement: The asset register was found to be inadequate toward the end of the project and was substantially upgraded to include all known assets. Much time is spent on research ing information on these items toward the end of the contract. Any item considered an asset Leighton-LAMA Joint Venture

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should be fully entered into an asset registry system upon purchase. Post project review, tracking and sale of such items are therefore made simple. The nature of the JV further complicates the issue since two separate parties have interests here. This system was not adequate at Manjung and should in future be implemented from the start of asset purchases.

Leighton-LAMA Joint Venture

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SECTION 9. RISKS/ LESSONS LEARNT 9.1. TECHNICAL 9.1.1.

Soil Investigation is paramount to minimize risk. Site-specific data must be collected for analysis and interpreted with due consideration of local knowledge. In this case the available information was not adequate or adequately interpreted. More attention should be placed on foundation conditions offshore in early stages. Cannot be stressed enough.

9.1.2.

Items such as the Dosing Line in this case should receive attention earlier. Cost could be reduced by optimizing resources. The risk of delays to unit placement was too high for such a small part of the overall structure.

9.1.3.

Anti- fouling measures are an ongoing risk up to the point of final hand over to the client. Costs involved in subsequent clean up operations could be significant. The anti-fouling paint used is merely a temporary measure and it is not agreed how long it would last.

9.1.4.

Environmental damage risk by the use of hazardous materials such as anti-fouling paint is high. Great care should be taken to ensure safe use and acceptable disposal of waste materials. Other materials including granular chlorine were used inside the culverts. These items must be treated with care and be kept to a minimum.

9.2. ADMINISTRATIVE, AUTHORITATIVE AND GENERAL 9.2.1.

On a large design and construct project a design coordinator is required on site for much if not all of the time. This engineer must have the authority to make decisions on behalf of the design office or have a mechanism in place to ensure that he receives quick decisions or feedback with minimum delay to the project. He should remain part of the design office structure and not get completely absorbed into the site management team.

9.2.2.

Where such an immense amount of quality assurance documentation is called for a specific QA person should be appointed and made available to hand le peripheral non-production issues. Site management can help set the system in place, fill in all check forms and so on but should not be expected to coordinate the vast quantities of paperwork submitted for prior approval and chase the record keeping.

9.2.3.

The cost of getting approvals for various aspects from the various authorities may have been included in the tender price but the effort spent on investigating and determining the exact requirements and the amount of lead time required for approvals was significantly underestimated. Recommend employing a local agent to deal with all authoritative approvals (departments of safety & health, fishing, environment, security, land usage, water, import/export, etc.)

Leighton-LAMA Joint Venture

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SECTION 10. STAFFING LEVELS 10.1. GENERAL COMMENTS On site staff for the project was supplied by both Joint Venture partners. LAMA provides all the expatriate engineers for the project. Leighton Contractors supply a number of superintendents on various part of the project and assisting office staff shared with the Leighton Office. LLJV supervisors and foremen are recruited locally. Labor is mostly subcontracted with their own first level supervision. Staff arrangements for the major section of the project follows below. 10.2. MARINE WORKS STAFFIN G FROM JULY 2000 TO F EBRUARY 2001 Position/Function Works Manager Senior Engineer Marine Superintendent Dredging Works (Ave Ceasar) Dredging Clamshell Piling Works Engineer Crane Barge & Pile Caps Gantry Superintendent Grouting of Main Joints Survey Works

Name Rudi Voerman Barry Hofmeyr Dean Pearson George Salmon Francois Labuschagne George Salmon Ooi Chin Tong Lee Yap Tan Richard Kevitt Kevin Findley Cheung Drikus Thiart Ooi Chin Tong

Notes (July 00 to Feb 01) (Feb 01 to Oct 01) (Nov 00 to Mar 01)

(Expatriate diver) (Nov 00 to Aug 01) Operator (Expatriate diver)

10.3. PRE-CAST YARD STAFFING Position/Function Senior Engineer Superintendent

Name Dean Pearson Greg Mackley Damjan Muhar Siva Muniandy

Cast 2 & concrete supply and pile caps Cast 1 & reinforcing supply Supervisor 1 (Cast 2 operations and plant) Aris Supervisor 2 (Cast 1 operations) Steve Ho Teck Seng Supervisor 3 (Formwork handling, plinth Mohamad bin Latif and pile caps) Supervisor 4 (Unit handling & transport, Aru temp storage preparation)

Leighton-LAMA Joint Venture

Notes Jul 00 to Feb 01 Mar 01 to end National Technician National Technician

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SECTION 11. SUBCONTRACTORS & SUPPLIERS 11.1. GENERAL This section serves as reference to the major subcontractors and suppliers utilized on the project. The most significant companies and their involvement are listed below. 11.2. MAJOR SUBCONTRACTORS Company CST Builders Sdn Bhd Forenede Plast Sdn Bhd Fuchi Engineering Sdn Bhd Geopancer Global Zodiac Heng Sum Sdn Bhd HUME Kawanda Sdn Bhd Kuan Industries Sdn Bhd (KIEC) L Double Sdn Bhd Lian Hup Yik Sdn Bhd Logic Global Sdn Bhd Macon Asia Mannesmann Rexroth Megalift Sdn Bhd Ng Jit Kee Trading & Construction PERI Hory Q&Q Builders Sdn Bhd Rekavista Sdn Bhd See Yong & Sons Sri Datai Sdn Bhd Starfish Underwater Services Sdn Bhd Tat Hong Plant Hire Sdn Bhd TEST Sdn Bhd Torsco Sdn Bhd Van Seumeren Widos Sdn Bhd

Service Provided Dosing line concrete works (in -situ) HDPE Butt Fusion Jointing Structural bracing of cofferdams In-situ piling Loadout jetty piling Coring, diamond cutting, demolition Concrete Marketing Sdn Bhd, Pre-cast concrete for dosing line Reinforcing Steel Manufacture of stone spreader and various other steel items Concrete works labour and supervision On-site welding of sheet piles, painting, concreting, miscellaneous. Concrete works (in-situ ) Trench dredging by Ave Caesar Hydraulic installations Heavy lift transport Offshore piling with Katara Tigra piling barge Formworks materials and design Concrete Works, in-situ culvert Labour supply to pre -cast yard Clamshell dredging Earthworks Diving services for offshore works General Crane Supply HDPE pipe pressure testing Gantry superstructure fabrication Heavy lift operations HDPE Butt Fusion Jointing

11.3. MAJOR SUPPLIERS AND SERVICE PROVIDERS Company Andy Khoo Arief Services Sdn Bhd Concrete Materials Laboratory Sdn Bhd Flexseal Enterprise Sdn Bhd Handelmax Sdn Bhd ICP Juara Marin King Ong Kuan Industries Sdn Bhd Leighton-LAMA Joint Venture

Service Provided Cofferdam excavation Marine labour supply Concrete cube testing Hydraulic fittings, general parts Labour supply Preca st spun piles Tug and towage, stone barge supply Crusher run Steel works, various services Section 11 : Page 1 of 2

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Company

Service Provided

Lee Trading Sdn Bhd Lian Hup Yik Sdn Bhd LT Piling Oriental Grandeur Sdn Bhd Oriental Sheet Piles Plimsoll Pioneer Sun Mix Sdn Bhd SAR Marine Sdn Bhd Spectest Sdn Bhd Sri America Travel Sdn Bhd Strata Drill Sdn Bhd Technilink Sdn Bhd Tools & Machinery Sdn Bhd WE Engineering Wing Tiek Wywysha Sdn Bhd

Marine craft, barges Manufacture and supply of steel members, sheet pile strengthening and related items Sheet piles Marine vessels supply Sheet pile supply Hoist and mooring winches, hydraulic power packs Ready mix concrete Feeder boat supply Onshore boreholes and various testing services Travel Agents Offshore boreholes, soil investigation Technical staff General tools, equipment, materials Embedments Sheet pile supply Labour supply

11.4. INDICATIVE RESOURCE PRICES (APPROXIMATE – APRIL/MAY 2000) Item Labourer Artisan Formwork labour 25t excavator hire 120t barge hire Crushed rock supply Sheet pile supply Structural steel fabricate Reinforcing supply Concrete supply, 45 MPa

Leighton-LAMA Joint Venture

Unit hr hr m² day month ton ton ton ton m³

Rate (MYR) 7.85 15.00 19.00 600.00 21 000.00 15.00 1 950.00 3 500.00 1 020.00 138.00

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SECTION 12. TEMPORARY WORKS 12.1. LOAD OUT JETTY 12.1.1. Background The Load out jetty was required to enable loading out of culvert units with the use of the floating gantry. Precast culvert units are placed on the temporary support walls on the jetty, after being transported into place with the use of the heavy lift trailers as supplied by MEGALIFT. The load out jetty was initially intended as a temporary works structure, but early on in the design process, it was requested by Alstom (The client), that the jetty be designed as a permanent structure. The jetty size is approximately 55 metres long by 10 metres wide. The jetty consists of in-situ concrete crosshead beams, supporting a pre-cast slab system, stitched together to form a complete working platform, sufficient to take the load of the trailer and 400ton precast culvert unit. 12.1.2. Design and Construct ability The jetty design was found to be simple to construct. Some of the items that needed to be considered carefully for construction according to this design were as follows: • • •

Accuracy of reinforcement position on PC slabs and in the in -situ connections The sealing of the Pile Infill cast to prevent leakage of concrete The control of the size of the slabs during the casting stage, to prevent creep during placing

12.1.3. Major Quantities Spun Concrete 700 mm Grade 80 Class C Piles Concrete (Cross head Beams/Infill/PC Slabs) Reinforcing steel

29 No 400 m3 75 ton

12.1.4. Program (Total time to construct = approximately 11 weeks) Item Piles Driven Precast Planks Pile Infill Casts Beams Slab Placing Cast Stitching

No off 29 77 29 12 77

Start 25/08/01 07/09/01 02/10/01 02/10/01 14/10/01 20/10/01

Complete 22/09/01 25/09/01 19/11/01 19/11/01 08/11/01 09/11/01

Duration 4 weeks 3 weeks 7 weeks 7 weeks 4 weeks 3 weeks

Ready for use: 16 November 2001 Actual Use for units: 13 December 2001 for load test of unit First use for permanent placing: 17 April 2001 In the early stages of the project the jetty was considered a critical path item. Once dredging commenced offshore, the priority was shifted to marine unit placing and unit foundation resolution. The jetty was not built at “top speed”. A realistic programme for this type of jetty should be approximately 8 weeks. Leighton-LAMA Joint Venture

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12.2. COFFERDAM Access for construction of the in-situ culvert section is provided by constructing temporary sheet pile cofferdams. The original design allowed for the in -situ construction in 3 phases, each with a separate, sequential cofferdam. This was later changed to combine the second and third phases and only two cofferdams were built. A third phase ‘Wing wall’-cofferdam (open at the offshore end) served to allow access for placement of the transition culvert joining the offshore section and the in-situ culvert. An extensive steel whaler and prop support system was designed and installed by Fuchi Engineering under LLJV supervision. The main cofferdams were constructed within an outer cofferdam. Light section LX16 sheet piles were used to construct the outer sheet pile wall. Large rocks are used along the outside to support the sheet piles and protect against wave action. The function of the outer cofferdam was to hold back sea water and provide access for the construction and servicing of the cofferdams. The client was greatly concerned by the possibility of damage to the diaphragm wall at the pump house water pool due to the proximity of the excavation. Excavation commenced only after major delays from the client regarding the stability of the diaphragm wall. Deflections in this area were constantly monitored to ensure stability was maintained. 12.2.1. Phase 1 Cofferdam Construction of the Phase 1 cofferdam commenced shortly after completion of the support pile installation. The phase 1 cofferdam is approximately 30m long x 13m wide starting from the face of the diaphragm wall. A combination of PU25 and LX32 sheet piles in 18 to 24m lengths were used for the 12m deep cofferdam and driven to the desired depth and set by vibrating hammer from a 150ton Crawler Crane. Excavation is carried out in sta ges to allow the installation of a 4-level whaler and prop support system to ensure a safe working environment inside the cofferdam. Excavation is by long-arm excavator from the surface. Support beams restricted access dramatically and two small excavators were employed inside the cofferdam to remove materials from the inaccessible areas. The cofferdam is dewatered by a well point pump. Upon reaching the required foundation level a 500mm deep 26mm stone bed was prepared over a geofabric layer. A lean concrete blinding was constructed to provide a suitable work platform at the required levels. The rushed nature of the construction after the initial delays did not allow sufficient time for planning and preparation of the work area. Working conditions were often uncomfortable. The main points of concern were restricted access due to heavily congested overhead support work. Dewatering was inadequate making final excavation very tedious. 12.2.2. Phase 2 Cofferdam A combination of available PU25 and LX32 sheet piles with additional stiffening was used for the construction of the Phase 2 cofferdam. This cofferdam is much larger than its predecessor accommodating the entire in-situ culvert. Several changes were incorporated to improve working conditions, access and subsequently the quality of work produced. It is important to note that the construction of the In-situ culvert became the critical path of the project after the initial delays.

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• •

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The cofferdam was made considerably wider, allowing access behind the outer walls of the culvert. This was a major problem in Phase 1 where support whalers were located within 500mm of the casting surface and the outside walls were inaccessible. The cofferdam was kept relatively dry by well designed and adequate dewatering pumps. This improved working conditions immensely with obvious benefits. Support whalers and props were redesigned to allow adequate headroom in critical areas and improve access to the work area for excavators, formwork handling etc.

Phase 2 is essentially an extension of the Phase 1 cofferdam. The offshore sheet pile wall from Phase 1 is extracted. A new wall is carefully driven several meters back onto the roof of the culvert forming the North wall of the dam. The east and west sheet piles from Phase 1 are removed back to this point. Sheet piles are now driven for the Phase 2 cofferdam in a different alignment making the cofferdam wider than Phase 1. Excavation and support work is completed in the same fashion as the Phase 1 operation. A very large tree (larger than 2m diameter) was found above foundation level at the offshore end and was trimmed down by chainsaw and excavator. This operation caused minor delays and accounted for the difficulty in driving sheet piles in this area. 12.2.3. Phase 3 ‘Wing-wall’-Cofferdam The “Wing-wall” system was designed to hold back soil onshore to allow the installation of the pre -cast transition unit connecting the offshore pre -cast culverts and the onshore in-situ section. Upon completion of the in -situ culvert construction the offshore end of the culvert was blocked by sheet piles and geotextile to prevent siltation during backfill. The cofferdam is gradually backfilled and compacted. With the backfill complete the offshore sheet pile wall was extracted including the first portion of the east and west walls. 30m wide “wing -walls” is driven either side of the culvert, tying into pre installed connection sheet piles fixed to the side of the culvert. During this phase the outer LX16 sheet piles had to be removed. At this point the wave action had reduced the level of the sand berm naturally. The area is excavated from land as far as possible and the all obstructing sheet piles removed. At this point the clamshell dredger (JETTA 19) resumed dredging up to the face of the sheet pile wing–walls to allow final driving to the desired depth. Onshore excavation continues to the same effect until the required levels are reached. The offshore wing-walls are driven to the required level (allowing the floating gantry access overhead) by the KETARA piling barge. The 10ton drop hammer proved problematic causing damage to the piles. A ‘dolly’ extension was fabricated since the final level was well below tide. A second set of “Dead -man wing-walls” are driven further onshore to anchor the front walls. Anchorage is provided by a series of steel cables tied through the front wall and anchored behind the rear wall. Offshore installation of the wires is carried out by divers. With anchorage in place final dredging was commenced. The clamshell dredged a trench in the seabed up to the face of the in-situ culvert without Leighton-LAMA Joint Venture

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any significant problems. The dredging is followed by piling, pile cap installation and finally pre -cast culvert unit placement. The sheet pile and goetextile closure at the face of the in-situ culvert is removed and the area prepared for the transition unit. The unit is subsequently placed and all the joints grouted. After thorough inspection of the works the area is allowed to fill naturally before removal of the wing -wall system. 12.3. REVETMENT WORKS To allow construction of the CWI culvert a section of the rock revetment surrounding the island had to be removed for the construction of the sheet pile cofferdam. Excavated rock and materials were stored on site for use in the subsequent repair to the revetment. The basic revetment consists of various layers of graded rock overlaying a geofabric membrane on sand. Excavation was by excavator from shore and later through a purpose built sand berm. WIBAWA EPC a specialist land reclamation contractor was approached for the repair to the revetment. Since they were directly involved in the original construction of the revetment their experience would prove useful in satisfying the client’s concerns with the repair. No significant problems were encountered during the repair work. Additional excavation was required due to large amounts of sand from the nearby “Outfall” construction site. This material was spoiled on site as directed by the client. Reinstatement starts with initial excavation over the affected area to remove sand backfill and silt to the required level. The existing revetment is exposed to allow sufficient overlapping of the geo textile layer. The original revetment rock had been stored nearby on site and separated according to the specified grading. The rock is built up in layers closely matching the existing layers either side. Excavation and rock placement are both regulated by tidal changes in the lower layers. With careful placement and constant survey monitoring of rock levels the revetment is built to final level. Final level rock is carefully placed to form a relatively even surface and seamless tie in with the existing revetment. 12.4. FLOATING GANTRY A 400t floating gantry similar to those used on four previous LAMA projects was designed to handle and place the precast units. 12.4.1. Hull Two identical barges measuring 120’ x 40’ x 8’ overall were hired from Lee Trading at a monthly cost of MYR 12 000 each and prepared to be configured in a catamaran arrangement with 14.2m clearance between them. The hulls were inspected and surveyed by an independent party. Bollards and bitts were repaired and fendering was supplied and fitted. 12.4.2. Superstructure After an exhaustive tender adjudication process a tubular steel structure of overall dimensions 21.9 x 16.5 x 16.5m was fabricated locally over a two month period and launched and secured onto the barges via the fabricator’s loadout facility. The superstructure was designed to support the load of a suspended culvert unit as well as withstand the forces generated as the two hulls moved under load in a swell in any combination of six differential actions.

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A separate walkway added to the stern sections provided no additional stiffness to the craft. A removable tie beam connected by 50mm diameter Macalloy post tensioning bars was incorporated on the forward section of the superstructure allowing the craft to approach and straddle a unit on the loadout jetty in all tide conditions. Final superstructure steel tonnages and costs were agreed with Torsco as follows: Main structural steel: 70.613t @ MYR 5 000 Walkways and ladders: 3.840t @ MYR 3 840 Pad eyes and gussets: 3.980t @ MYR 9 900 Erection of total steel: 78.433t @ MYR 1 250 Extras (walkway beams, additional padeyes etc) Total cost to supply, fabricate and erect

MYR MYR MYR MYR MYR MYR

353 065 26 496 39 402 98 041 19 758 536 762

The detailing particularly of the ladders and walkways was not accepted by the fabricators as being included in their works so an external consultant was commissioned to assist with the workload. Most items were fitted during the construction phase at Lumut Port where it is eventually inspected and certified sea worthy. The barge was towed to the Manjung Power Station construction site upon completion and the balance of the installations finalized. Stringent material and weld testing was carried out in compliance with the fabricator’s quality assurance procedures. Another consultant was commissioned to follow up all aspects of the Department of Safety and Health (DOSH) involvement leading to the issuance of a certificate of compliance. This certification aspect originally overlooked almost led to major delays. At the end of the project it was agreed with the owner of the two pontoons to take over the entire gantry structure for his disposal or use. 12.4.3. Mooring equipment Four 10t mooring winches with manual band brakes (two with warping drums) were fabricated by Plimsoll of Singapore at approximately SGD 17 000 each and fitted to the gantry barges. Central hydraulic controls were installed and plumbing connected to the main hydraulic power unit (HPU.) Four roller fairleads were fabricated and installed by Lee Trading who also manufactured four new 2t delta flipper anchors. 300m of 24mm diameter IWRC mooring wire rope was fitted to each of the mooring winches. 12.4.4. Lifting equipment Two 25t hoist winches with spooling gears and failsafe brakes were built by Plimsoll and purchased with central controls at approximately SGD 79 000 each and installed, one on each hull. Winch plinths were fabricated and welded to the deck and a non-shrink grout was cast under the foundation beams to spread the load evenly into the barge deck. Initial problems with the spooling gear developed but were remedied by replacing the drive chain sprockets. Two 350m lengths of 36mm diameter SWR were fitted to the hoist winches and fed through single sheave deflector blocks anchored at deck level before going up into Leighton-LAMA Joint Venture

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the hoist rigging. Two pairs of 200t SWL 5-sheave hoist blocks supplied by Plimsoll at approximately SGD 20 000 per pair were fitted to the superstructure and each reeved into 10:1 arrangements. Theoretical lifting capacity was therefore 2 x 10 x 25 = 500t. Two lifting spreader beams fabricated by Besteel Berhad in KL for a total of MYR 64 000 were suspended via four doubled 64mm SWR slings to the lower hoist blocks. Each beam housed two lengths of 75mm diameter Macalloy post tensioning bar from McCalls Special Products in Dubai, which connected the lifting equipment to the corbels of the precast culvert units through bearing plates, spherical nuts and washers. The lifting beams had to undergo similar DOSH inspection and certification processes as for the superstructure. Two 8” bore diameter hydrau lic cylinder delivering 50t tension load over a stroke of 1.8m were purchased at MYR 8 000 each and supported below each of the two lifting beams. 32mm Herc Alloy reeving chain connected to either end of the cylinders ran through horizontal holes in the p recast units’ corbels and was used to pulled the units together by bearing against large locking plates. Rope brakes were installed to ensure that sufficient tension was applied to the slack hoist wire when spooling back onto the winch drums after placing a unit. The brakes comprised lengths of hardwood timber held in steel channel frames sandwiching the rope by adjustable pressure delivered by 2½” bore hydraulic cylinders. A number of load sensing devices were considered but they were all a bit expensive. DOSH conceded that load sensing or limiting devices would not be essential as long as the floating gantry was physically unable to lift more than the rated load. A load test to 125% of the working load was done and attended by the relevant authorities. The 500t test weight was made up of a 400t precast unit loaded above with 100t of additional block kentledge. 12.4.5. Hydraulic Circuitry A 180 kW (2 x 90 kW) HPU was built and supplied by Plimsoll at SGD 55 000. This provided all the hydraulic power for the two hoist winches, four mooring winches, two unit installation cylinders and the two hoist rope brakes. Mannesmann Rexroth did hydraulic plumbing, pre-pickling, flushing, testing and commissioning of both the floating gantry and crane barge at a total cost of MYR 127 000. Some minor problems occurred after initial usage and were remedied fairly quickly. As production improved and utilization of the hydraulic equipment intensified, a hydraulic cooling system was deemed necessary and installed. 12.4.6. Other De ck Equipment and Hydraulic Circuitry A 200 kVA generator was hired and fitted to the floating gantry mainly to provide electrical power to the 180 kW HPU. A distribution board was provided and electrical circuitry provided for deck lighting as well as domestic lighting and power. An air-conditioned container was provided for the control cabin and another container supplied for the store.

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12.5. STONE SPREADER SUPPORT / CRANE BARGE 12.5.1. Barge hull A 180’ barge was hired from Lee trading for the crane barge. A minimal amount of refurbishment was required prior to the hire and a third party inspection company conducted an on hire survey to assess the condition. 12.5.2. On board equipment The barge was fitted with six new 10 ton mooring winches purchased from Plimsoll at SGD17 000 each; four of which provided the four-point mooring and the other two were for lifting the stone spreader when it was moved from bed to bed. Four 2 ton delta flipper anchors were made by Lee trading and fitted to the ends of the 300m 24mm diameter IWRC anchor wires. Fairleads and bitts were manufactured and fitted to the barge. A 150t crawler crane was hired from Tat Hong at MYR 40 000 mob/demob and MYR 45 000 per month. The crane had a 1m² grab for feeding the stone to the stone spreader. A 45 kW HPU was purchased from Plimsoll for SGD 17 000 and fitted and plumbed to provide hydraulic power for the four mooring winches, two lifting winches as well as the stone spreader. Mannesmann Rexroth did hydraulic plumbing, pre-pickling, flushing, testing and commissioning of both the floating gantry and crane barge at a total cost of MYR 127 000. Heat generation problems later resulted in the need to install a heat exchanger to reduce the hydraulic oil temperature. 12.5.3. Other facilities Side boards were erected and braced in the centre of the barge to provide a stone bin to keep a supply of spare stone on board. Containers were fitted for a control room, divers change room and a store. Lean-to shaded areas and a water tank were erected. At a later stage when the barge was used for placing pile caps it wat fitted with a RTK DGPS positioning system. 12.6. STONE SPREADER The stone spreader design is basically an improved version of the previously used spreaders from the Saldanha and Luanda contracts adjusted fo r the specific project requirements. The spreader machine is basically a 1 x 1m stone hopper in a bogey which runs transversally on a 16m long traveling frame which runs longitudinally on a 20 x 14m base frame on four hydraulically adjustable legs. Level adjustment of the main frame is achieved by hydraulic cylinders extending or shortening the legs. Hopper movement is provided by hydraulic motors which drive the traveling frame longitudinally and the hopper bogey transversally. Although it could have been modified to be operated remotely from the surface, it is controlled on the seabed by divers who need to get immediate feedback on the movements and to check the stone level in the hopper. Various quotations were sought and the manufacture contract awarded to Kuan Industries (KIEC) based in Ipoh, approximately 50 km inland of Lumut. The supply and installation of the hydraulic drive system was awarded to Mannesmann Rexroth of Kuala Lumpur. During Leighton-LAMA Joint Venture

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the construction of the spreader it was discovered that the revised drive system using grooved drum winches and continuous pull wires could not function as intended and the concept had to be abandoned. After due consideration the previously used chain and sprocket system was reintroduced with slight modifications. The stone spreader was fabricated and commissioned in Ipoh in eight weeks before being knocked down for transport purposes. It was then delivered and assembled on site and fully tested by the divers who familiarized themselves with the machine and its controls. There was a delay of some weeks waiting for the dredging of a suitable area but the machine was loaded onto a barge, taken offshore and deployed into position on the seabed for the first time in early January 2001. The machine it screeded the first stone bed in just over a day and produced acceptable bed levels within a tolerance of 25mm. It was moved to the next bed position but by then general consensus was being reached on the unsuitability of the seabed soil conditions for the designed stone foundation and the piled solution began to emerge. The spreader was removed from service after having completed only one bed and was subsequently dismantled, cleaned up and stored on site for future disposal.

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SECTION 13. PRECASTING OPERATIONS The offshore section of the Cooling Water Intake Culvert is constructed by placing 142 No. precast reinforced concrete culverts end-to-end on a pre-constructed foundation (piles in this case) and sealing the joints. These units are pre -cast on land under controlled conditions and transported by heavy lift trailers to a jetty for placement offshore. 13.1. UNITS MANUFACTURED IN THE PRECAST YARD No Off 141 77 6 460 99 312

Description 400 ton Precast Culvert Units 7 to 10 ton Load Out Jetty Pre-cast Deck Slabs 150 ton Precast Intake Head Units 3 ton Precast Plinths temporary storage of culverts 2.5 ton Precast Slabs for M176 Turbine Building Precast Pile Cap

Production Rate 1 per day 6 per day 7 weeks total 10 per day 6 per day 4 to 6 per day

A summary of Pre -cast Culvert construction is included in Appendix B.1 for reference. 13.2. LOCATION AND SIZE OF THE PRECAST YARD There were two choices for the position of the precast yard. The first position was along the revetment, parallel to the shoreline, and stretching from the load out jetty eastwards for approximately 200 metres. This area was not used due to concerns about stability of the revetment in the area. The second area was 1.5 kilometres from the jetty alongside Alstom and Peremba Offices. This area was not fa voured due to the distance from the load out jetty, and the interface between general site traffic and the unit bearing heavy lift trailers. All factors being considered, the second area was chosen for the final location of the yard. The overall dimensions of the yard were 90 m x 75 m. The area had to be levelled prior to precasting beds being constructed. Following the levelling of the area, which consisted of dredged fill/reclaim material, a 200 mm to 250 mm layer of crusher run was levelled over the whole area and compacted to 95 % Mod Aashto. This was required due to the heavy cranes and heavy lift trailers which travelled on the area, to facilitate general construction and movement of the units. As there were no services (water/sewage/electricity/telephone/air) in this area, these services had to be installed by the LLJV Precast Yard team. 13.3. SERVICES IN THE YARD Offices:

2 no fully outfitted 20 foot containers served as staff offices. Fitted with Telephones Stores: 3 no 20 ft store containers were used to stock and manage the consumables and tools for the yard Shelter: There was approximately 300 square meters of overhead roofing provided as undercover work area, lay-down, and labour rest area. This undercover area was covered with a blinding layer for a hard -standing area. Water Line: 63 mm Diameter HDPE line fed from the Alstom controlled tanks opposite the yard. Approximately 500 meters of water pipe was used in total. Electricity: Supply by LLJV hired 100 KVA Diesel Generator. Cables supp lied by LLJV (Approximately 200 metres of suitable cable). Air lines: Instead of using mobile compressors, it was decided to use a stationary compressor. Feed lines were underground using 2 inch GI Pipe. 150 metres Leighton-LAMA Joint Venture

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of pipe laid for this use. There were 12 strategically placed up-stand air service points servicing the PC beds. The compressor used was a 275 KVA diesel machine. A 40 foot fitted container was purchased and a conservancy tank placed underground alongside this 40 foot ablution block. 12 no overhead light masts (site detail) for night work provided elevated light with 400 watt floodlights. These could be relocated by crane to light the active work area as required.

13.4. LABOUR FOR THE PRECASTING WORKS Due to the availability of suitable companies/small businesses it was decided early on that we should utilize a labour only subcontractor for carrying out concrete, reinforcing and formwork labour operations. Tender packages were sent out to seven (7) companies who all quoted accordingly. Various methods and reasons were used to procure the contractor to carry out this work. Rekavista (otherwise known as Ikmas Jaya), were eventually awarded the contract in early August 2000. In total this company provided approximately 120 no labour to complete the works. It was noted that this company “sub-sub & sub -contracted” the work requirement. This led to certain difficulties in managing the amount of resources on site. Once the systems and labour teams were established, the routine set in the precast yard production targets were met comfortably each day (1 unit per day, 6 days per week). 13.5. LLJV LABOUR It was found necessary to have approximately 20 no LLJV directly employed labour in the precast yard to assist in areas where the subcontractor did not perform, had bad turn outs, or in areas where extra works were required due to late changes in details. Storekeepers, welders and office cleaning labour were supplied by the LLJV. The direct works were carried out by an appointed sub-contractor, according to a bill of quantities, and tendered rates. A number of prices were submitted for this work (Appendix B.3). It was found that tender rates had probably been leaked out of the system, to some of the tendering parties. Rekavista was finally appointed as the sub-contractor to carry out the works, based on rates submitted for formwork assembly, reinforcing, formwork and concrete placement. The LLJV supplied approximately 24 labourers to provide store facilities, scaffolding erection, cleaning, rigging, and general backup works. The PEAK LABOUR in the precast yard reached approximately 150 no labour (Appendix B.2). It was noted from the structure of the labour only sub contractor that he had a piece -work system implemented within his own sub -contract with us. He seemed to have subcontracted each trade, and this lead to a couple of disputes amongst the parties involved, and also some delays to the precast yard. With the repetitive nature of the work, the labour side of the precast yard evened out and ran smoothly, and daily targets were met without excessive overtime. During the construction works, the sub-contractor persistently fought the pricing, and in cases threatened to demobilize from site due to their continuous loss of money on their agreed rates. Certain extras were then negotiated. The end result on the financial outcome of the labour portion of the precast yard was not as profitable as initially expected.

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Precast Culvert Construction: LLJV Labour Team Labour Description

Direct

Supervisors Foreman/Leadmen Carpenter Welder General Worker Rigger Mason/Concretor Scaffolder Steelfixer

3 1 0 2 3 0 0 0 0 9

Broker

Rekavista

0 1 11 0 0 8 1 6 0 27

3 8 20 0 48 0 4 0 22 105

Total 6 10 31 2 51 8 5 6 22 141

36 It was found necessary to have approximately 20 no LLJV directly employed labour in the precast yard to assist in areas where the subcontractor did not perform, had bad turn outs, or in areas where extra works were required due to late changes in details. Storeke epers, welders and office cleaning labour were supplied by the LLJV. LLJV labour was required for start up, and for assisting the sub-contractor in areas where they were behind on programme - S/C was back-charged . A dedicated scaffolding crew was required to ensure that access was safe and erected as required for smooth operations. It is difficult to categorize the labour descriptions as they are multi-skilled and generally of a similar standard in skill, production & motivation. The above team was capable of producing one completed culvert unit every day on average 13.6. REINFORCING OPERATIO NS 13.6.1. Quantities Total reinforcing for the Precast Yard was broken down as follows (approximate) Quantity 1 Lot 141 no 77 no 6 no 460 no 312 no

Purpose

Tonnage

Site Establishment in Yard (Plinths/Beds) 400 ton Precast Culvert Units 7 to 10 ton Load Out Jetty Precast Deck Slabs 150 ton Precast Intake Head Units 3 ton Precast Pedestals temporary storage of culvert Precast Pile Cap Total

22 ton 2 685 ton 50 ton 60 ton 92 ton 152 ton 3 061 ton

13.6.2. Cost Supply of Steel (excluding cutting & bending) Bar Size 10mm 12mm 16 to 32mm 40mm (not used) Leighton-LAMA Joint Venture

Rate (MYR/ton) High Tensile Mild Steel 1 078 1 043 986 1 043

1 043 1 009 952

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Add RM 150 per ton if cut & bent by exte rnal suppliers. RM 138 per ton if cut & bent by Leighton reinforcing yard. 13.6.3. Supply Reinforcing was initially supplied cut and bent by the Leighton Steel Fabrication Yard, at the allowable rate as per tender. Cutting and bending rate = RM 150 per ton. Due to overload of the Leighton Yard, it was found necessary to order reinforcing in from external sources, namely Kawanda Corporation. This company supplied reinforcing, and further acted as an agent and sourced the cutting, bending, and delivery service from other yards, one being Southern Steel SDN Bhd. Approximately 900 ton was supplied by the Leighton Yard, and the remaining 2 289 ton was supplied by Kawanda. Problems were experienced in the early stages with both yards related to incorrectly bent reinforcement, and the misinterpretation of bending schedules. These were ironed out as the work progressed. All external steel deliveries were from Kuala Lumpur. 13.6.4. Fixing Labour Production Fixing rates varied from 13 man-hours per ton to 30 man-hours per ton. The average for the culverts was approximately 25 man -hours per ton (Appendix B.4). Precast Culvert Reinforcement Production: fixing only Area Base Wall Prefixing Install Cages Top Slab Guide Nib Shearkey Corbel Total

Ton in Area 8.2 3.2 Prefixed 5.6 0.5 0.5 1.1 19.0

Fixers

Time(hrs)

12 5

11 11.5 8 6 3.5 3 4 46.5

15 4 8 6

Mhrs 132 57.5 7.5 90 14 24 24 401.5

Mhr/ton 16 18 60 16 28 50 21 25 (Average)

These are average figures achieved on this area of the works. Light duty galvinised bunched wire used for tying. Labour only sub -contractor was used for all fixing works. Total no of fixers on site = 30 no including s/c supervisor. 13.6.5. Ordering and management on site The best system for managing the steel flow to site was found to be the routine delivery system, and having complete unit deliveries arriving according to the program being achieved in the precast yard. One unit worth of steel had a mass of approximately 19 ton. This was sufficient to fill one semi- trailer truck, and on arrival this was easily checked for missing bars and incorrectly supplied bars. Once the units were being produced at one complete unit per day, the steel deliveries followed the same routine. Steel arrived on site by 08H30 each day, and was offloaded into one of the four empty precasting beds, which was allocated to reinforcing deliveries on a rotational basis. On offloading a section engineer and Leighton-LAMA Joint Venture

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one of the labour only sub-contractor representatives checked the steel as delivered, and reported any inconsistencies, which were then followed up and resolved in most cases. 13.7. CONCRETE OPERATIONS Total Concrete for the Precast Yard was approximately 23 250 cubic metres. Concrete grade was 45MPa Minimum Cement Content, Early Strength, Marine Grade Concrete (pumpable). The mix design was as follows: Cement (Masscrete 30%) Water Stone Sand Additive 1 (Daratard 17 D) Additive 2 (Daracem) Water Cement Ratio Slump 1 day strength 3 day strength 7 day strength 28 day strength 56 day strength

485 kg 160 litres 990 kg 725 kg 0.97 litres 4.850 litres 0.33 100 mm 15.0 MPa 26.5 MPa 36.5 MPa 53.0 MPa 64.5 MPa

See also Appendix B.9. 13.7.1. Supply Concrete was supplied by a central batching plant, owned, and run by Pioneer Concrete. The batching plant was situated alongside the precast yard (within 200 meters). The same batching plants were used to supply concrete to the Leighton’s Main site, Bachy, the LBT Jetty, and Peremba. All concrete was delivered using 6 cubic meter truck mixers as owned and operated by Pioneer Concrete. 13.7.2. Placing of Concrete The majority of the concrete was placed by concrete boom pump, which did not require the use of cranes and concrete buckets. Tremie pipes were used to place concrete in the top cast, down into the walls, due to the high concentration of steel, and the depth of the pour. The intake units and precast pile caps were all concreted using crane and concrete bucket methods. Concrete was placed at a rate of 20 to 25 cubic metres per hour. Supply generally did not limit the rate of pour. The nature of the pour and the vibration required tended to be the limiting factor. Concrete was vibrated using air driven vibrators. These were efficient and robust. G & W Equipment supplied concrete pumping equipment at a cost of RM 8 per cubic meter. 13.7.3. Ordering and tracking All concrete was ordered using standard concrete order forms, submitted one day before the applicable pour. Every pour on site was allocated a progressive pour number. Concrete quantity, location, and cube results were all referenced back to this pour number. A pour register for the site was maintained, making all concrete Leighton-LAMA Joint Venture

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records traceable. Concrete cost was RM 130 per cubic metre for delivered concrete. Prior to each pour the pump had to be primed with 1 to 2 mixes of cement rich slurry, for which we were also charged. Leighton paid the Pioneer Concrete account, and back charged the LLJV according to matched delivery notes and pour register records. 13.8. STORAGE AND HANDLING OF UNITS Megalift and Mammoet (2 suppliers) were approached to quote on the heavy lift transport portion of our works. Both priced and a final agreement was reached with Megalift after negotiations. The trailer used was not an SPT (Self propelled trailer), but was a trailer which required to be towed by a mechanical horse/prime mover, and assisted by a D7 dozer where necessary. The trailer was operated by personnel from Megalift (approximately 7 no men). The services offered were very efficient. Cost of the transporting spread per month was RM 118 000 inclusive fuel, dozer, labour and drivers. Units were moved and handle a number of times each in some cases (up to 4 times each). Details of the machinery are included in Appendix B.5 & 6. The majority of the units were completed prior to placing operations commencing. All 142 units had to be placed in temporary storage. This temporary storage was not anticipated at tender stage. Precast concrete stools were cast in the precast yard. These stools could be crane handled into the correct positions for storing units in an elevated position. There were 480 no of these required. All temporary storage areas were prepared using earthworks plant and sub -base/crusher run materials. Prior to load out for placing, there was a temporary holding area to which the units were transported for preparation for placing. This was located very close to the load out jetty. All units were handled at least three times each. First handling was the load out from the precast yard to temporary storage. Second was from the temporary storage to the preparation area. Third and mostly final handling was from temporary storage to the load out jetty. Reaching a monthly hire agreement with the heavy lift transport company was a good option in this case. 13.9. PLANT REQUIREMENTS 13.9.1. Cranes Various crane options were considered for the precast yard: • • •

Tower Crane on travelling base and a fixed tower crane Crawler crane (80 ton) and tower crane combination 2 no Crawler (80 t)/2 Mobile cranes (25/45 t) only

After considering cost of all options, it was decided to use the third option. Crawler cranes are readily available at low rates. Mobility of the cranes, costs, and general versatility were all advantages of using the crawler cranes. 13.9.2. Hiab Truck, man lift and fork lift The above plant items were required to assist in the movement of reinforcing, precast stools, formwork, and materials generally for the site.

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The boom lift (manlift) proved to be very useful for accessing the high points on the culvert units for patching and repairs, and reduced the requirement for scaffold erection to carry out his work. Scaffolds were time consuming to build, and also congested the area. Refer to the Typical Precast Yard Plant breakdown Schedule and costs (Appendix B.7). 13.10. MATERIAL REQUIREMENTS AND INFORMATION Most materials were east to find. problems: • • •

The following materials posed some procurement

Uni-strut: no suitable off the shelf material found Chamfer: no hard wearing durable chamfer ob tainable. Plastic chamfer of very poor quality, timber chamfer only lasting 1 to 2 no used. Shutter-board was found to be expensive, and not of very good quality. 12 re -uses was the best we could obtain from even the imported board. The extreme heat and humid conditions did not contribute to long lasting form-board (wetting- drying- heating cycle).

13.11. CUSTOM EQUIPMENT Various items were made on site to simplify and smoothen out our operations: • • • •

A Tunnel Formwork winch and table system Staircases Mobile light masts 200 litre drum handling stands

13.12. FORMWORK Various methods of casting the units were also considered: • • • • •

Cast the full culvert unit base, walls and roof slab as one (1 cast system) Cast the base, then the walls, then the roof (3 cast system) Cast the base including a 1 metre kicker section, followed by walls and roof (2 cast system) Cast the base without kicker, then cast the walls and roof as one. Cast the base, then the kicker incorporating the corbels, followed by remaining walls and roof (a varied 3 cast system)

Various options were considered for the formwork in the Pre -cast yard: • • • •

Peri Hory Formwork using shutter board for facing RMD System using steel and shutter board for facing Custom Made Steel Form System: steel facing SGB System

In addition to this, corbel, stop -end, and guide nib forms considered were either of steel or timber. After consideration of cost, available time, technical issues, equipment available, it was decided to cast the base without kicker, then cast the full wall and roof section as one cast. The formwork choice was PERI HORY SYSTEM. (Refer Appendix B.8 for an extract from the Peri Hory Catalogue 2001/2002). This company, having an office based in Kuala Lumpur offered design services for the use of their system, and produced comprehensive drawings Leighton-LAMA Joint Venture

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for fabrication and assembly of the forms. The majority of the formwork was provided at a square metre rate of RM 7-80 per square metre of formed face. This rate reduced for soffits to approximately RM 5-80 per squa re meter. The quantity of formwork was calculated based on achieving 9 units per week of 6 days. This was a theoretical calculation which turned out to be a good base for calculating the quantity of formwork and utilization factors. Base Table Forms Base Side Forms Internal Tunnel Forms External Wall Forms Stop-ends Corbels

6 sets (enough to form 6 no bases) 4 sets 6 sets 4 sets 4 sets 2 sets

The LLJV purchased all shutter board and the internal whalers (custom made) for this formwork. There were some problems related to the use of these forms: • • • • • •

• • •

Forms were not robust enough. We often found that items were being broken in the lifting, handling and casting operations. The supplier was unable to provide sufficient formwork materials in time for our operation, and seemed to be over committed on the main works. The system was loose and provided problems in tying the forms together and achieving the dimensions required. Jacking and propping systems were not very efficient. The systems external forms were under-designed in the whaler area, interfacing with the corbel position. Bearing pressure from the channel soldiers caused compression of the timber girders used as whalers. Peri did not take into account the support pressure on the ground for the base cast. This resulted in load spreading slabs having to be cast to spread the load under these jacks. The response, when queried, was that their designers in Germany had handled the base cast (with a kicker) as a beam, which apparently assisted in the support of the mass of the top cast. In fact the base was not being cast with an up -stand kicker/”beam”. The folding in splay section at the bottom of the form provided a poor finish in the concrete at this point. The detail was make shift, and not designed to suit the system. Fixing of the shutter board to the Peri Girders also posed some problems. The fixings often pulled through the board on stripping, especially on the splayed areas in the lower wall portions of the culvert. The timber stop-ends provided were not robust and had to be repaired prior to every cast. Eventually steel stop-ends were purchased.

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13.13. FINAL PREPARATION OF CULVERTS 13.13.1. Background Prior to load out each culvert unit requires a number of fittings and preparations. A preparation area is provided at the load out jetty with a five - culvert storage capacity. Culvert units are stored at various locations around the Manjung site prior to final preparation. Once the pre -cast concrete works are complete the culverts are transported to the preparation area by heavy lift trailer. The culvert is placed on temporary plinths until it is ready for load out to sea. 13.13.2. Preparation Works The productivity of culvert preparation is entirely dependent upon offshore placement of culverts and supply of new culverts for preparation. Marine conditions and progress dictates the pace of culvert placement. On the Manjung project we had the unfortunate situation of delayed placement of culverts. This resulted in having large numbers of culverts in storage over a large area of the site. Culvert preparation was done in one area only due to the availability of services and plant. We were able to manage the required production without delaying culvert placement. We were however directly affected by delays in culvert placement. Once the culvert is securely placed on the plinths safe access is provided by crane and riggers. A pre -constructed access scaffold is placed and secured alongside the culvert. An 18mm poly-rope safety barrier is provided along the edge of the top slab. A variety of preparations are made as described hereafter: Survey fittings: Purpose made eyebolts are installed at each corner of the culvert top slab. They serve as known connection points for survey (pencil)-buoys once the culvert is submerged at sea. Joint Preparation: Factory made geotextile grout socks are pre -fitted to the grout recess on one side of each culvert unit. The grout sock consists of two layers of geofabric (Polyfelt TS 70) stitched together to form a sealed sock (cylinder). The grout socks are pre -manufactured and delivered to site. A 25mm PVC grout pipe is inserted on site to predetermined positions inside the socks. The grout sock is folded in a controlled manner and secured with a nominal amount of electrical insulating tape. The folded sock is fixed to the grout recess on the culvert face by rubber straps nailed to the concrete. Lorry inner tube is cut to 1” strips for this purpose. Through grout trials this has been found to be an optimu m size for securing the sock without restricting the grouting of the joint. The ends of the grout socks are checked to protrude at least 600mm above the top slab of the culvert and secured. Two separate grout socks are fitted to each unit. A 25m long “U-joint”sock is fitted along the bottom slab and continued up both outer walls. A shorter (13m long) “Top”-grout sock is installed along the top slab. At first a number of grout socks were site manufactured. These comprised a 10” Layflat hose (Sunny hose) with a single layer of geotextile on the outside. The geotextile was cut and fit on site. Portable bag sewing machines were used for stitching outer geotextile bags. Stitching was generally of a lower standard than the factory made socks. These grout socks were installed and grouted without any major problems. Due to the high cost of the layflat hose (imported from Japan) additional grout testing was done on a geotextile-only grout sock. Two layers of Leighton-LAMA Joint Venture

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geotextile were separately stitched by a subcon tractor under factory conditions. The grout test is carried out successfully and the balance of the grout socks manufactured in this manner. No serious problems were encountered with the offshore grouting of these socks. Due to reduced head pressures under water some problems were encountered with the opening up of the grout socks. In some cases too much insulating tape was used to secure the socks. Rubber holding straps also caused restrictions during the grouting operation and divers had to break the se by hand. The problem is overcome by finding the optimum spacing and size of strapping used for securing the grout sock to the culvert. This should be adequately strong to withstand the short term effects of wave action during load out of the culvert units. Grout socks were ripped off the culvert face on two occasions only. In both cases the socks were exposed to wave action for prolonged periods of time. A rubber silt seal is provided all around the culvert at the joint face. 76mm Diameter heavy duty rubber hose is fitted along the outer edge of the joint face. When adjacent culvert units are pulled together during placement the rubber hose is compressed and the culvert effectively sealed from its surroundings. The main function of the seal is to provide a temporary silt seal prior to grouting of the joints during the construction phase. It acts as secondary seal in the permanent condition. The hose is supplied in rolls of 100m, cut to the required lengths and fixed to the concrete surface by means of roofing nails which proved adequate for this purpose. The rubber hose had the additional function of supporting the horizontal sections of grout sock during the grouting operation as they had a tendency to sag due to gravity. Dosing Line : The concrete dosing line structure is fitted to the culvert unit in the preparation area. This operation is discussed in detail in Section 11. Anti fouling : The internal surfaces of each culvert is painted with anti-fouling paint within 24 hours before load out of the culvert unit. This serves to prevent marine growth on the inside surfaces of the culverts during the construction phase. In this manner the culvert is handed over with minimum flow restrictions avoiding expensive and time consuming cleaning ope rations. Only a single layer of paint was used as the temporary measure. Quantification of the effective lifespan of the paint proved difficult with no experience at hand. All concrete surfaces are thoroughly cleaned by high -pressure hose prior to application. Unit Numbering: Each culvert unit is visibly marked with its placement position number for identification underwater. A 300 x 200mm number is painted inside each tunnel and on the top slab of each culvert. Normal aerosol spray paint is used. General: Prior to load out each culvert is thoroughly inspected for quality of finishing and completion of all preparation works Refer CHK -P-034 -F (Appendix B.10). All pre -cast checklists are checked to ensure the culvert is acceptable for placement. Final concrete repairs are carried out as required. The lifting corbels are checked for accuracy of construction and concrete strength. The opening at the bottom of each lifting corbel is checked and any obstructions removed by cutting torch to ensure safe lifting operations. The culvert is cleared for load out after final inspection and acceptance by the client’s representative.

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13.13.3. Suggested improvements/Other useful information •

•

•

•

•

It is an advantage to have the maximum amount of culverts prepared to avoid delays. Production is regulated by the placement of culverts and any delays impact directly on the preparation works. With a larger number of culverts a smaller team is required to ensure timely preparation of culverts without delays. Most preparation work should be carried out in the pre-cast yard (including installations such as Dosing Line Structures) using the same resources and access. Specialist tasks such as manufacture of grout socks should be done in a controlled environment to ensure quality. Risks involved in poor quality are much greater than any additional cost involved in factory made socks. Site labour proved unskilled in this specialized field and site conditions do not promote quality or productivity. Culvert preparation could be done in advance by moving the operation to the various culvert storage areas. This would require more resources since services are required in various areas. Culvert placement was often delayed by weather and other factors directly impacting on the preparation works. Culvert preparation should ideally be carried out in the pre-casting area using resources to the maximum. Where long -term storage is involved preparation works should be carried out in advance. Final preparation works should be incorporated in the overall production cycle and not be treated as a separate entity. Time constrained items such as the anti-fouling paint requires little resources to be moved around site. Due to the nature of Anti-fouling paint great care should be taken with the storage, handling and eventual use of these materials. Environmental and safety risks are substantial. Actual lifespan of the anti-fouling paint was never confirmed giving rise to fears of inadequate protection if chlorination is delayed extensively. It is therefore advised to prepare an experimental concrete surface (i.e.: a test piece) for periodic review of the performance of the paint in the same conditions as that used in the culverts.

13.13.4. Human Resources Task Grout Socks Anti- fouling Paint Eye bolts General Total

Own Labour

Own Supervision

5 carpenter 3 labour

1 Foreman

Subcontract

2 labour 1 labour 2 riggers

1 Supervisor 1 Foreman 1 Supervisor

13.13.5. Plant and Machinery • • • • • • •

25 Ton Rough Terrain Crane (shared with Dosing Line and marine craft loading work) 60’ Hydraulic Boom-lift Additional 40’ hydraulic boom-lift employed at height of production Concrete Coring Equipment (Dosing Line) HILTI concrete drills (TE 76 and TE 15) Portable bag sewing machines Portable generators/ lighting plant

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SECTION 14. IN-SITU CULVERT AND COFFERDAM 14.1. SCOPE This section describes the construction of the 68m long in-situ section of the Cooling Water Intake Culvert and its connection to the Water pool onshore. 14.2. WORK DESCRIPTION The In-situ culvert section serves to connect h t e onshore water pool with the pre-cast culverts placed offshore. Safe access is provided by means of a series of sheet piled cofferdams approximately 12m deep. The initial design required the construction in 3 phases with three separate cofferdams on a sequential basis. The In-situ culvert was constructed in 2 phases eventually. The first step was to provide access and a stable working area. To this end a section of rock revetment was removed and a berm constructed with fill material over the full extent of the in situ work area. An outer sheet pile cofferdam was driven and the. The in-situ section is supported on a grid of 400x400 Square Reinforced Concrete Piles driven from the surface prior to excavation. Piles were periodically cut down as excavation progressed to the required levels. Construction commenced within the Phase 1 cofferdam adjacent to the water pool. Excavation proved tedious in the heavily propped cofferdam. Access was restricted and the water exposed clay proved difficult to remove. A 24m section of culvert was constructed from the face of the water pool diaphragm wall. in similar fashion to the pre-casting operation. Great care had to be taken not to disturb the diaphragm wall during the construction process. The offshore end of the culvert was temporarily sealed off and the cofferdam backfilled and compacted. Sheet piles were removed from the offshore face. The Phase 2 cofferdam was constructed from this point to the end of the in-situ culvert in similar fashion to the Pha se 1 operation. A number of lessons were learnt from the first cofferdam and implemented in Phase 2. Restricted space was a major concern and the Phase 2 design allowed additional access along the sides of the culvert and less congested cofferdam support work overhead. Additional pumps were employed to ensure adequate dewatering. Working conditions were much improved in Phase 2. It is important to note that the In -situ culvert proved to be the critical path on the project in contrast to the original planning. This was mostly due to initial delays by the client based on concerns surrounding the integrity of the water pool diaphragm wall. Further difficulties during the course of the project kept this section on the critical path despite the major delays incurred with the change to a piled design. 14.3. PILED FOUNDATION A series of 400 x 400mm square Reinforced Concrete Piles were driven from the surface prior to construction of the cofferdams. These piles serve as main foundation support for the in-situ culvert section. Piles were cut down incrementally as excavation progressed on the 12m deep cofferdam. The off-cut sections are sacrificial and balanced against the reduced cost of driving the piles from the surface as opposed to a post excavation scenario in restricted space. Refer Appendix C.1 for additional piling data.

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Two piles were damaged during the excavation of the Phase 1 cofferdam. Each pile had to be excavated to expose the damaged area and repaired to the satisfaction of the designers and client. The combination of vertical piles and horizontal support beams in the cofferdam made excavation awkward and severely restricted. 14.4. PHASE 1 CONSTRUCTION All works are subcontracted under LLJV supervision. Concrete works commenced by preparation of the support piles to design detail. Reinforcing steel was supplied by the site Rebar Yard and fixed by subcontract labor. Logic Global provided labor and supervision for all in-situ culvert related works. The Phase 1 culvert was constructed in three sepa rate casts. Refer Appendix C.2 for Summary of concrete pours. The entire base (24m long) was cast from the Diaphragm wall to the first movement joint. Less than 500mm headroom was available due to the cofferdam support work. Culvert wall starter bars had to be replaced with mechanical rebar coupled bars at considerable cost. With the base completed the lower levels of cofferdam supports are removed for construction of the walls and roof slab. 12 m long tunnel forms were assembled in position from the face of the diaphragm wall. Formwork proved tedious with limited access and poor ventilation. Walls and roof slab was cast in two 12m long sections to complete the first 24m of culvert. Tunnel forms were mounted on castor wheels and could be moved as a unit. After completion of the 24m long section the open end of the culvert was blocked by sheet piles and the cofferdam backfilled progressively. A sheet pile wall was carefully driven behind a purpose built concrete kicker across the top slab of the Phase 1 culvert. The offshore sheet piles from the first cofferdam is extracted. Due to the delayed start of the in-situ works the program was extremely demanding. Many problems encountered were only addressed in the Phase 2 cofferdam due to the tight construction schedule. 14.5. PHASE 2 CONSTRUCTION With the cofferdam completed the temporary sheet piles are removed from the face of the Phase 1 culvert. A pump breakdown during the construction of the Phase 2 cofferdam caused the area to flood with subsequent damage to the tunnel formwork left inside the Phase 1 culvert. Formwork was redesigned to cast wall separate from the top slab. The base slab was cast well in advance followed by individual wall casts. The top slab was completed progressively. At this stage ventilation inside the culvert tunnels came to the fore as a safety concern and a large extractor fan was employed to ensure safe working conditions. The entire culvert was inspected, repaired and signed off before backfilling. Three HDPE launch sle eves were installed from the offshore end of the in-situ culvert to the surface adjacent to the culvert chimney structure for the purpose of launching the Dosing Line after backfill was completed. A chimney structure was constructed approximately 30m from the water pool connection. The chimney allows access to the in-situ culvert from the surface. The main purpose of the chimney is to provide access for the installation and eventual removal of the temporary steel bulkheads fitted to each tunnel at this point. The bulkheads are designed to prevent seawater from flooding the water pool during the construction phase. The offshore portion of the CWI culvert is flooded long before the water pool is ready to be filled. A 12” Gate valve is fitted to the center bulkhead for controlled flooding of the water pool at a later stage. Three Leighton-LAMA Joint Venture

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separate concrete caps are provided to cover the chimney structure in the permanent condition. 14.6. CONNECTION TO THE WATER POOL The In-situ culvert is connected to the water pool through the diaphragm wall. The connection is essentially a movement joint. The first step was to break through the 1m thick heavily reinforced diaphragm wall. A specialist subcontractor achieved the breakthrough by diamond cutting to the profile of the three-celled culvert. Cutting was done from the inside of the water pool. After preparation of the movement joint the tie-in concrete was cast to complete the connection to the water pool approximately 12m below the natural ground level.

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SECTION 15. MARINE WORKS 15.1. GENERAL 15.1.1. Scope This section describes all offshore and marine related activities involved in the construction of the Cooling Water Intake Culvert. Refer to Appendix D.1- 3 for Culvert Unit Placement summaries, Marine Staffing and Labour and an Offshore Works Overview. 15.1.2. Work Description The cooling water intake structure is for the most part located offshore which qualifies it as essentially a marine project. A variety of offshore activities are discussed in detail within this section. A summary of the major Marine Works components are listed below: • • • • •

Trench Dredging works Offshore foundation works (Stone foundation vs. piled foundation) Diving operations in general (underwater works include grouting, unit placement, investigations, pipe installations, repairs) Pre-cast culvert unit transport and placement Hydrographical and general marine survey

15.2. TRENCH DREDGING 15.2.1. Scope This report covers the Trench Dredging Works for the Cooling Water Intake Culvert at the Manjung Power Station. 15.2.2. Background and Dredging Enquiries To accommodate the buried Cooling Water Intake Culvert and its foundation a 1 450m long trench had to be dredged along the seabed to the required levels varying up to 4m below the existing seabed. A trench invert width of 14m was required and the width at the top was as much as 50m, depending on trench depth and material stability and an approximate total of 250 000m³ of material was initially estimated. The stone bed foundation design required accurate dredging to avoid excessive stone material wastage and differential settlement problems so a level tolerence and a further dredge accuracy incentive were offered in the enquiry which effectively discouraged the use of most rough cutting trailer suction and cutter suction dredgers. The tender design also had some engineered backfill and rock armour placed either side of the completed culvert so these activities were offered as options to be included in the dredging subcontractors scope of works. At the onset of the project a dredging specification and tender document were drawn up and issued to the following contractors: 1. 2. 3.

Antara Koh, Singapore No quote - not interested Ballast Needam, Singapore No response Boskalis, Holland No dredge quote but interested in the stone bed

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4. 5. 6. 7. 8. 9. 10. 11. 12. 13.

East Marine, Singapore GET Systems, Singapore Jan de Nul, Singapore Lo & Loh, Singapore Macon, Holland See Song, Malaysia See Yong, Malaysia UDL Dredging, Singapore van Oordt ACZ, Singapore WH Chan, Singapore

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No quote No quote Submited tender Received two submissions Offered “Ave Caesar” Submitted tender No quote – too busy No quote Full proposal offering Macon’s “Ave Caesar” Did not quote

The complete tenders received with amounts in MYR compared as follows:

Dredge only

Backfill only

Dredge and backfill

Item Mobilise Dredge trench Maintain trench Demobilise Total Mobilise Sand fill Rock armour Demobilise Total Mobilise Dredge tre nch Maintain trench Sand fill Rock armour Demobilise Total

Quantity Sum 250 000m³ 1 430m Sum Sum 30 000m³ 30 000m³ Sum Sum 250 000m³ 1 430m 30 000m³ 30 000m³ Sum

Jan de Nul 1 716 115 4 735 417 0 734 937 7 186 468 497 029 3 977 750 4 432 350 213 283 9 120 413 2 213 144 4 735 417 0 3 977 750 4 432 350 948 220 16 306 881

Loh & Loh 385 500 3 500 000 572 000 257 000 4 715 000 385 000 540 000 2 850 000 257 500 4 033 000 771 000 3 500 000 572 000 540 000 2 850 000 515 000 8 748 000

See Song 350 000 3 375 000 457 600 80 000 4 262 600 450 000 1 800 000 3 450 000 100 000 5 800 000 500 000 3 375 000 457 600 1 800 000 3 450 000 150 000 9 732 600

Jan de Nul provided Dayrates for their cuter suction dredger “Marco Polo” at USD 84 000 working and 53 000/day standby. Although this dredger was amongst the largest in the world there was concern about the degree of achievable level accuracy so Jan de Nul also offered a sophisticated and multi functional crane vessel “Pompei” and a dump barge which would have worked out to MYR 12.3M over a six month hire period. Van Oordt ACZ offered Macon’s “Ave Caesar” plus dump vessels at a lump sum price of MYR 9.2M but we had already approached Macon directly who offered the dredge at substantially lower rate with an estimated total of MYR 3.1M for six months excluding fuel, consumables and a dump vessel. This option was the clear commercial winner and was also the only dredger that was both immediately available and capable of achieving the tight level tolerance. After satisfying ourselves that it suited the production rate required for the program we entered commercial negotiations and commenced making mobilisation arrangements. 15.2.3. Dredging with the “Ave Caesar” Some preparations to the “Ave Caesar” were required before it could be mobilised from Batam. After handling a number of enquiries with various tug owners and marine towage contractors, Lee Trading was contracted to tow the dredger to site.

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Dredging commenced on 24 th October 2000 after erecting the spuds and releasing all the sea fastenings. The “Ave Caesar” was a Liebherr 994 Litronic Excavator turret-mounted on a semijackup pontoon. The three spuds are not able to lift the pontoon clear of the water but can provide enough lift to hold the pontoon at a stable level unaffected by the short-term water movements. Two of the spuds provide lift and the third provides both lift and longitudinal movement when taking a sliding step. Monthly hire cost is MYR 750 000 based on a single shift. The “Ave Caesar” is fitted with an electronic Real Time simulator to facilitate accurate dredging work. A Differential Global Positioning System (DGPS), electronic Gyro compass and electronic Tide Gauge were supplied by the J.V. and incorporated with the on-board systems to provide complete three-dimensional control of the dredger and it’s bucket at all times. Initial difficulties were experienced with the integration of the equipment but specialist survey companies were consulted for the final integration of equipment into a workable system. Once operational the system proved very useful for unassisted movement of the dredge and accurate dredging to the requ ired tolerance. The “Ave Caesar” has a dedicated crew and operators who were familiar with the machine and proved very competent in almost all operations and maintenance activities. A dedicated LLJV Engineer was on board almost full time to manage and witness the operation. Appendix D.4 shows an example of daily dredging records kept and a graphic summary of trench dredging with the “Ave Caesar”. Dredging was a 24 -hour operation with subsequent saving in rental. Refer to Appendix D.5 for typical dredge production figures for both a 12 and 24-hour operation. One disadvantage the backhoe dredger had over other dredgers is that the jack-up spuds would penetrate up to 10m in the seabed material and the damage would effectively negate or reduce the seabed bearing capacity. This had a little impact on the piled foundation but had far more significance when considering the effect on the originally detailed stone bed design. For this reason attempts were made to keep the dredger’s spuds out of the trench which slightly reduced it’s productivity. Extra effort was also spent checking that the dredged tolerances were met before the dredger moved off an area. For this reason the bucket was used to systematically sweep the dredged area checking for high spots before making a step. The trench was excavated according to profiles programmed into the computerized display. Refer Appendix D.6. Excavated material is loaded into a 1000m3 SplitHopper Barge “Cathay SHB 1006” (At MYR 65 000 per month from Oriental Grandeur plus additional MYR 8 000 for 4 maintenance crew members) moored adjacent to the Dredger. An 800hp tug “Cathay 28” was dedicated to handling of the barge for dumping of spoil and Dredger assistance. Refer to Appendix D.7 for details of the dredging spread. The excavated material was closely monitored and examined as dredging commenced. Material in the hopper barge is constantly monitored by visual inspection and shear vane test. The excavated seabed was repeatedly inspected by divers to establish the nature of the founding material. The material was soon found to be unsuitable for the stone bed foundation as designed. Material consisted of variable clays, which would liquefy once exposed by excavation (Refer Appendix D.8 for the Trench Seabed Material Survey Record). In the initial dredging stages

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the machine was moved to various areas on the trench route to produce useable trench in acceptable material. The foundation conditions were thoroughly examined and an alternative piled foundation was adopted. The relatively small excavator bucket then proved less efficient in the liquefied material. The “Ave Caesar” was off-hired on 15 th March 2001. During this time most of the bulk dredging was completed. A 20m3 clamshell (Jetta 19) was hired to replace the Dipper Dredger since the need for accuracy was reduced. Refer to Appendix D.9 for data on the Clamshell dredger. The large capacity clam proved to be better suited to the conditions and dredging was generally satisfactory. Monthly hire costs ware significantly reduced to MYR 450 000 inclusive of a 1200hp tugboat and 1000m3 hopper barge. Observations taken between 01/11/00 and 09/02/01 showed that the Ave Caesar backhoe dredger excavated 58% of its total working time and averaged 207m³ per excava ting hour as in the summary below.

Activity Final cut Bulk dredge Dump spoil Maintenance Repairs Step/reposition Other Non operating (sleep) Total Actual excavating effort Dredge: Operate factor Dredge:Total time factor Dredged quantity Dredging production

Ave Caesar Dredging Production Unit Nov 00 Dec 00 Jan 01 Feb 01 Hrs 0 144 216 75 Hrs 213 179 229 79 Hrs 59 58 82 39 Hrs 29 32 26 2 Hrs 5 20 47 19 Hrs 50 80 106 27 Hrs 13 118 6 0 Hrs 351 113 33 0 Hrs 720 744 744 240 Hrs 213 323 445 154 % 58% 51% 63% 64% % 30% 43% 60% 64% m³ 56 491 58 849 81 748 37 380 m³/hr 265 182 184 243

Total 434 700 238 89 91 262 137 497 2 448 1 134 58% 46% 234 469 207

The average daily production on a double shift could then be estimated as 2 881m³/day (24 hrs x 207m³/hr @ 58% efficiency) but the production rate varies tremendously with material types. Firm material will fill the bucket in a short scoop and will result in as much as 400m³/hr but sloppy mud described as ‘soup’ will yield a very low solid contents value. The total invoiced value of the Macon charter for the “Ave Caesar” running between 20 October 2000 to 13 March 2001 was as follows: Total Invoiced Value for “Ave Caesar” (MYR) Mobilisation and Prep dredger 34,100 demobilisation On/off hire survey 6,513 Sea tow survey 8,491 Ave Caesar Single and double shifts 2,187,714 dipper dredger Settlement discount -164,079 Dredger insurance 188,790 Personnel Operators 724,853 C'coordinator 201,943 General Flights 48,987 expenses Consumables & airfreight 89,663 Total 3,326,975 Leighton-LAMA Joint Venture

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This figure does not reflect a number of back charges nor a payment claim that occurred some time later as a result of disputed damage repairs. 15.2.4. Dredging with the “Jetta 19” With the decision to replace the culvert stone foundation with a piled foundation, the need for tight level tolerance dredging fell away to a more economical dredging solution. Furthermore the piled foundation required a trench cut approximately 0.5m deeper which with the geometry of the side slopes resulted in a significant increase in the total material quantity. In January 2001 enquiries were again sent out to the following dredging contractors: 1. 2. 3. 4. 5. 6. 7.

Ballast Needam Oriental Grandeur See Yong & Sons See Song & Sons Benalec Tidal Marine Asbil

The Ave Caesar finished up and left the site in February 2002 and the clamshell dredger “Jetta 19” from See Yong & sons was towed to site from Penang and commenced dredging at the beginning of March and completed the trench dredging. 15.2.5. Dumping of spoil Spoil from the trench excavation was dumped by the split hopper barge in an existing “Sand Re-handling Basin” conveniently located within 2km from the trench. The alternative to this area was located adjacent to the nearby Pankor Island. Such an operation would be costly due to the long hauls, additional tugs and hopper barges required to ensure an efficient operation was maintained. The re -handling basin could be filled to levels corresponding with the surrounding natural seabed. Spoiling operations were not sufficiently controlled from the outset leading to reworking the area before termination of the Clamshell Dredger’s service. A survey done on the spoil dump site in Februa ry 2001 showed a dumped quantity of 187 000m³, 16% lower than the volume of material cut from the culvert trench. This is probably due to survey inaccuracies and/or material being lost along the way from the trench to the dump site. The 1 000m³ split hopper barge and 800 HP tug were hired from Oriental Grandeur at MYR 66 000 and 45 000 per month respectively. 15.2.6. Survey of dredging works Besides the positioning of the actual dredger, additional survey was required to verify the actual dredge depths achieved on site. Hydrographical surveys were carried out by echo -sounder in combination with a Real Time Kinetic Global Positioning System (RTK GPS) mounted on a small power boat. A dual Frequency echo sounder (33kHz & 210kHz) was utilized to indicate both the top of the soft silt layer and the under-laying firm material. Output from this system was rarely accurate and numerous difficulties were experienced with the equipment.

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Unfortunately this issue was never fully resolved but alternative survey subcontractors were deemed extremely costly. 15.2.7. Other Dredging Works Smaller scale dredging was required from time to time to remove silt around the load out jetty and in the vicinity of the Transition unit. A Toyo Pump was utilized for such localized dredging. It could be handled by crane from the jetty or shore and spoil is discharged through a floating pipeline to a suitable location nearby. This equipment was generally in poor condition but its limited use negated serious implications. 15.2.8. Suggested Improvements • •

•

Soil investigation proved to be the major problem in this project. Accurate knowledge of the material involved is essential in the choice of dredging equipment. In this case the cost implications were significant. Electronic (DGPS) positioning of the dredger proved very efficient and is certainly an advantage. Cost is high and it would be worth training operators properly in the use of the equipment. Specialists in the field should be consulted from the start. Dredging is by nature a high cost exercise. Contracts need careful consideration and works should be planned thoroughly to ensure optimum use of equipment.

15.2.9. Plant (Refer Appendix D for more information on major plant) • • • • • • • • • • • • •

S-Type Dipper Dredger “Ave Caesar” with Liebherr 995 Litronic Excavator “Cathay 28” 800 HP Tugboat “Esprit XI” 1000m3 Split Hopper Barge Clamshell Dredger “Jetta 19”, Tug boat and hopper barge. Toyo pump c/w floating discharge pipe sections (poor condition) Diesel generator (Hired on occasion for dredging) Survey boat DGPS receivers Gyro compass Electronic Tide Gauge Dual Frequency Echo Sounder Various computers and related electronic equipment Feeder boats (shared)

15.3. STONE SPREADING As explained elsewhere it was originally intended to found the culvert units on a 0.5m thick screeded stone bed but this was changed to a piled foundation after it was discovered that the seabed material had insufficient bearing capacity for the stone bed design. Nevertheless the principle of the stone screeding activities are recorded here for future reference. 15.3.1. Resources • •

180’ stone spreader support barge with 4-point mooring, 2 x stone spreader lifting winches, HPU, 150t crawler crane & grab, generator, office and store containers 180’ stone material supply barge (owned by locally based stone supplier)

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750 HP tug to move barges (shared usage) Stone spreader machine (described under section on temporary works) powered by HPU on support barge Floating hopper and fall pipe 10” submersible Toya pump & discharge hoses 4-man support barge crew and crane operator 5-man dive team with air dive spread and communications 4-man tug crew with skipper (shared) Land surveyor with theodolite, level, pencil buoys, survey stations

15.3.2. Operational steps •

• • •

•

• •

• •

Confirm seabed to be screeded is dredged to level tolerances and is free of excessive marine mud, slush and obstructions. If not, use the 10” Toya pump in a systematic pattern suspended by the 150t crane or use the crane’s grab. Confirm acceptable bearing characteristics of the seabed. Lay geofabric over bed area by spooling off a roll suspended by the crane. Geofabric to be pre-weighted with stitched in reinforcing bars or similar. Move support barge over spreader machine. Lower and connect lifting wires. First lift machine’s inshore legs off the completed bed, then the offshore legs. Keep machine about 1m above seabed. Move barge to new bed area. Position spreader machine suspended by support barge over the area and lower to the seabed, offshore legs down first, then inshore legs onto previously completed bed. Confirm positional accuracy by surveying the pencil buoys attached to machine and by physically checking sufficient overlap on the previous bed. Disconnect lifting wires. Connect hydraulic umbilical to legs. Lift and lower machine to set on level. Surveyor uses dumpie level from shore or intermediate piled survey platforms. Confirm all level, steady and secure. Disconnect hydraulic lines and recover umbilical. Move support and stone material barges into position. Move floating hopper into position, lower, install and secure fall pipe. Connect hopper hydraulic umbilical. Move hopper onto previously screeded bed. Place stone in floating hopper with the crane’s grab. Diver on the seabed drives the hopper in a set pattern when it is sufficiently full of stone. Diver to ensure the hopper does not run empty or overflow. Diver to ensure the entire bed area is systematically covered with no gaps or overruns. Screed the entire bed complete. Surveyor with dumpie level to check the screeded levels by sighting on a pencil buoy floating above a heavy plate moved around the bed in a set pattern by diver. Confirm all nine shots are within level tolerance. If not re-screed bed. Disconnect fall pipe and remove floating hopper. Move machine’s hopper to a central position in the frame for even weight distribution. Disconnect hydraulic lines and recover umbilical.

15.3.3. Suggested Improvements As there was only one complete bed screeded and the learning curve was not yet overcome there were no significant improvements on the equipment or method suggested for similar future works.

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15.4. PILING WORKS 15.4.1. The change to piling It was found in late December 2000, that the stone bed design was not compatible with the ground conditions being experienced in the offshore trench. No founding level could be established and maintained with any success. Rock dumping was attempted in order to try and firm up the excavated trench material, but this was also not successful. From 1 January 2001 to 28 January 2001 various unsuccessful attempts we re made at trying to find suitable founding at different chainages along the trench. Core sampling and laboratory testing was carried out on the material and finally on 2 February 2001, at an LLJV meeting a decision was made to adopt a piled solution. Th is design change due to the unforeseen founding conditions occurred 7 months after the start of the project. 15.4.2. Piling Progress From 2 February 2001 to 30 March 2001, the design was carried out, and all approvals and testing requirements for the piled solu tion were put in place. Subcontracts and suppliers were set up and the first working pile was driven on the 30 March 2001. The piling progressed well and on the 20 July 2001 the piling rig went onto standby due to delays experienced on the cofferdam and in turn dredging of the last 300m of trench. During the standby time, the navigation structure piles, intake structure temporary piles, and load out jetty test piles were driven. The piling restarted on 13 August 2001 after the dredging up to the cofferdam was completed. All piling was completed by 17 August 2001. Refer Appendix D.10 & 11 for further details on piling works. 15.4.3. Pile Driving A subcontractor on unit rates carried out pile driving. The subcontractor, KETARA TEKNIK, supplied the equipment for driving, labour, tugs, barges for pile delivery, and collected all the piles from the local factory at Lumut Port. A “follower” had to be constructed to enable driving underwater. This was constructed from a steel pipe pile of 900mm diameter, and approximately 26 m in length. This was later trimmed down to approximately 16 metres. A number of interesting issues arose from the underwater pile driving: • • • •

The piles should be sealed units, not allowing water into the bottom of the pile, top of the pile or through the breather holes which are sometimes left in the side of the pile. The piles should be driven in an “air condition”. This was achieved by sealing the follower within the helmet of the follower, and pumping air into the “bell” area of the follower where it interfaces with the pile at the driving end. All the marine/underwater driven piles had a conical, pointed, steel shoe welded onto the bottom of the pile. This stopped the ingress of a “plug” and water, both of which would have caused the piles to break during driving. The “air pocket” at the top of the pile therefore stopped water from entering the pile. A continuous air pocket was maintained during all driving underwater. 2 no 175 CFM compressors were used for this purpose.

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The driving efficiency was still quite good using the follower, especially after shortening. The packer proved extremely important in ensuring that the pile did not break during driving. We used layers of 21mm shutter board (approximately 150mm to 200 mm total thickness). Positioning of the piles underwater was achieved with the “Target Pile” survey system. A realistic accuracy on positioning turned out to be 200mm from design centre of pile. The hammer used for pile driving was a Twinwood 10 ton hydraulic dro p hammer. The hammer stroke was variable and electronically controlled up to 1000mm. 15.4.4. Piling Production We achieved 3 to 4 piles per day on average with 30 m long piles. When driving the shorter 26 m piles we were able to achieve 6 piles in a 10 to 12 h our day. The total number of blows for a 30 m pile generally varied between 1000 and 1800. Pitching, driving the above water section, fitting the follower, driving the underwater section, varied from 2 to 3 hours of driving. Weather played an important role in the productions achieved. It was found that side on swells caused problems with the accuracy of the piles as driven, and at times could also have lead to the breaking of pile heads, due to the angle of impact of the hammer on the pile head. 15.4.5. Pile supply ICP Sdn Bhd supplied all the spun concrete piles for our works. The suppliers were able to produce 4 to 5 piles a day with ease once the moulds were set up. Due to a late start on the piling option, there were some delays experienced due to the availability of cured (ready to drive) piles. The cost of the piles was RM 320 per metre. 15.4.6. Pile Testing The behaviour of Test piles where monitored using PDA equipment (Pile Driving Analyser equipment), and re -strikes with the same equipment after set up. It was found that the piles were setting up well in the offshore material, and capacity was reported to be increasing two fold after 21 days of set up. Underwater PDA equipment was procured (RM 20 000) from the USA to test offshore working piles. This testing indicated piles were being driven to requirements and were meeting the design capacities without any problems. One of the test piles was tested using the STATNAMIC TEST. This test measures the mobility and load bearing capacity of the piles follo wing a single impact from a hammer which is energised by an upward explosive device, which sends the hammer mass upwards, and results in the hammer free falling and striking the top of the pile. Various test instruments are set up on the pile and the resu lts are analysed and checked for conformance and verification of the design. This test was carried out on site on the 22nd May 2001. 15.4.7. Surveying the piles Positioning of the piles was achieved using a Real Time Kinetic Global Positioning System (RTK GPS). Pile driving position was monitored throughout the driving by a computer and software (“Target Pile”) system linked to the GPS equipment. The LLJV had a full time engineer (Lee Yap Tan) on the piling rig responsible for monitoring the positioning of the piles. The plan position accuracy of the piles was Leighton-LAMA Joint Venture

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generally within 200mm of the design centre. Level control was achieved by conventional survey, standing on a temporary survey platform located on the test pile. Graduated accurate level marks were placed on the follower for reading similar to a staff. Once the pile approached the final drive level, the surveyor controls and instructs the piling team when to stop. The level control on the piles was managed to ensure as far as possible that the pile was driven slightly (20mm to 50mm) deeper than the design level. The actual level was then measured using pencil buoys and plates. The pile cap thickness was adjusted to suit the ‘as-driven’ level of the pile. This ensured that the culvert unit would be su pported at the correct level on the pile cap. 15.5. PILE CAP PLACING & G ROUTING Pile caps were manufactured in the precast yard. The first pile caps were placed on 11 April 2001. Pile caps were offloaded at the load out jetty by the precast yard team using a HIABtruck and a 45 ton (or 25 ton) crane. 15.5.1. Equipment employed on pile cap placing • • • • • • • • • •

Crane Barge 60 m x 20 metre 80 ton Crawler crane 4 point hydraulic mooring system 7 no Marine labour 1 no expatriate diver 1 team of 4 to 5 divers and their equipment Lifting slings and lifting beam RTK GPS system Underwater epoxy materials for bedding the pile cap on the top of the pile Grout pump, holding tank, and materials for grouting and testing the grout

15.5.2. Process followed to install one pile cap Pile caps were loaded from the load out jetty onto a tug and transported out to the crane barge (ex stone spreader barge). Pile caps were lifted onto the crane barge by the 80ton crawler crane on the barge, and were then prepared for placing. This preparation incorporated the following items: • • • • • • • • •

Check the grout tubes are correctly positioned and not blocked. Check that the grout tubes are correctly identified (breather versus grout tube). Check the thickness of the cap was correct and suited the as built pile level. Confirm that the internal diameter of the pile (measured prior to delivery/driving), suits the external diameter of the pile cap. Check that the geotextile section at the end of the pile cap shaft is correctly fitted, secured, and not too large. Check tha t the number of the pile cap suited the number of the pile in which it was to be placed. Check that the plug head (guidance system), was in place and secure. The custom-made pancake grout bag was secured to the pile cap in a specially recessed area of the pile cap. The pancake itself was essentially a small empty grout mattress made of geofabric. The underwater epoxy was then applied to the pile interfacing area on the underside of the pile cap bearing area.

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The RTK GPS equipment was used once again to accurately position the barge over the piles, which were to accept the pile caps. Piles were lifted using the cast in wire rope lifting hooks, and guide into position using a diver on communications. Alignment of the pile cap was achieved using a 3 -point reference system, which consisted of two points on a lifting beam supporting the pile cap, and a long distance point on land. During placing all three points were lined up such that the North South alignment of the pile cap was as accurate as possible. Once the pile was correctly aligned, and with 2-way communication between above water crew and the diver, the pile cap was lowered into the opening in the pile. The pile cap was then grouted into place using the tested and approved underwater grou t mix. Divers carried out the grouting with underwater communications.

It was found that the grout quantity turned out to be very similar in each case. Questions were raised by the client’s representative, as to the integrity of the grouting. Tests were again carried out on the crane barge to prove to the client that the system worked as required. After placing the as built level on top of the pile cap was taken by a survey platform based surveyor. 15.5.3. Productions achieved on pile cap placing Between 6 no and 10 no Pile caps could be placed and grouted in a day. Poor sea conditions had a negative effect on production. It was found that the piling was holding up the pile cap placing. This was not a critical path activity, and a lag in the program could easily be recovered in a day or two. Refer Appendix D.10. 15.6. CULVERT UNIT PLACING 15.6.1. Resources • • • • • •

Twin hull 400t floating gantry with 4 point mooring and 400t hoist system (as described under temporary works section) with barge master and 5 riggers/deckhan ds 750 HP anchor handling tug with skipper, motorman and 4 deckhands (shared usage) 10” submersible Toya pump & discharge hoses 4-man support barge crew and crane operator Dive barge with air dive spread and communications and 5-man dive team (shared usage) Land surveyor with theodolite, level, pencil buoys, survey stations

15.6.2. Procedure • •

Deliver culvert to the loadout jetty by heavy lift trailer and lower unit onto the support plinths thus allowing the trailer to move off. After taking tide into consideration, disconnect and lift the gantry’s front tie member, move the floating gantry in on its moorings to straddle the jetty and line up over the culvert unit. Secure craft and refit tie member.

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Lower the two spreader beams by the hoist winches and handle into alignment to engage over the culvert unit’s four lifting corbels. Connect the beams to the corbels by the vertical Macalloy bars, washer plates and nuts. Lift the culvert unit clear of the jetty structure by the hoist winches. Carefully warp out clear of the jetty on the floating gantry’s mooring winches. Lower the culvert unit somewhat to improve the stability of the craft and its 400t load. With assistance from the attending tug, recover the gantry’s anchors and tow gantry to the placing site. Deploy mooring anchors again in a prearranged spread pattern on arrival. Place marker buoys on offshore end of previously placed culvert to mark its position. Winch the gantry into position on its moorings and secure. Lower the unit towards the seabed with 0.5m clearance offshore the previously placed unit. Divers talk the culvert into position while adjustments are made on the gantry’s mooring winches and the hoist winches. Rest culvert squarely on support pile caps with half a metre clearance from the previously laid unit. Give slack in the hoisting system. Diver to connect the two tensioning cylinders in a horizontal line on either side between adjoining corbels of the previously placed unit and the new suspended unit. Once connected with the chain and other rigging provided, take up some of the weight of the new unit with the floating gantry’s hoist system and simultaneously activate the cylinders to deliver 50t tension load. With the previously placed unit offering more sliding resistance than the partially supported unit, the new unit slides up against the previous one into final position. The guide nibs provide the final alignment and the rubber seal would be sufficiently compressed to provide an adequate seal prior to the joint grouting operation. By “steering” the unit with independent left and right cylinders one can make adjustments in the horizontal alignment of the new culvert’s offshore end. Check and confirm the position, clearances and alignment of the new culvert is within tolerance. Lower the lifting system again and slack off. Extend the tensioning cylinders disconnect and recover tensioning cylinder rigging. Disconnect spreader beams from corbels and recover. Pick up anchors and tow floating gantry back to loadout jetty. Moor floating gantry back onto its anchor spread and prepare to receive the next culvert unit.

15.7. CULVERT UNIT JOINT GROUTING The sealing of the joints between the culvert units was always considered a critical activity but more so here after the downtime and high consequential costs suffered on a recent similar project in Hong Kong due to the failure of joint seals which allowed seabed material to de drawn into the intake works of a functioning power station. 15.7.1. Resources • • •

10 x 6m grout barge with soft rope moorings, store for stock of cement bags, fresh water tank, grout mixer/pump and hoses with 4 man crew. 12 x 8m dive barge with control/store cabin, air dive spread, hiab and 5 man dive team. 750 HP anchor handling tug with skipper, motorman and 4 deckhands (shared usage)

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15.7.2. Procedure • • • • • • • • • • •

Moor grout barge onto position over pile bent. Moor dive barge onto position. Diver connects grout delivery line into the deflated “pancake” grout mattress already affixed in the pile cap recess under the placed culvert unit. Mix grout mixture slurry comprising pure cement and fresh water in the mixer/pump. Fill the pancake with the grout under gravity flow until flow stops (pancake full.) Disconnect grout hose and seal receiver hose in pancake. Connect grout hose to lower u -shaped grout sock in culvert joint recess. Mix grout and full the grout sock under gravity flow until full. Disconnect grout hose and seal receiver hose in grout sock. Connect grout hose to upper straight grout sock in culvert joint recess. Mix grout and full the grout sock under gravity flow until full. Disconnect grout hose and seal receiver hose in grout sock. Move dive barge to next site. Move grout barge off to restock materials for next pile bent.

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SECTION 16. DOSING LINE 16.1. GENERAL 16.1.1. Scope This section covers the construction of the HDPE Hypochlorite-Dosing pipeline for the Cooling Water Intake Culvert at the Manjung Power Station. 16.1.2. Background Three separate 225 O.D. HDPE pipes are installed between the electro-chlorination building onshore and the Cooling water intake Units at the offshore end of the culvert. Each pipe serves a single tunnel of the culvert. The pipelines are installed along the top of the culverts and protected within a concrete kerb- and slab structure. 16.2. CONSTRUCTION METHOD Site preparation for Dosing Line works commenced on 15 March 2001. Delivery of pre-cast concrete elements from HUME Concrete Marketing was delayed and the in-situ construction of Dosing Line structures was actioned to avoid delays in culvert placement offshore. Dosing Line installations were carried out in the culvert preparation area at the load out jetty. Plant and access to culverts could therefore be shared. The spreadsheet in Appendix E.1 summarizes all concrete installations by type and method of installation for each culvert unit. 16.2.1. In-situ Concrete Installation A reinforced concrete kerb, diaphragm wall and slab arrangement is installed to each individual culvert. This serves as a protective housing for the HDPE dosing lines. The site team opted for a pre-cast solution manufa ctured by a subcontractor and delivered to site for installation. To avoid delays in culvert placement initial dosing line structures were cast in-situ. 37 In-situ installations were done in total. To avoid delays additional cost was incurred in formwork and subcontract labour. Simple plywood and timber formwork was prepared on site by specialist subcontractor. Reinforcing steel is supplied and bent by the on site Rebar Yard. The position of the Dosing Line structure is set out on the top slab of each individual culvert by surveyor, clearly marking the outlines and dowel positions. A system of T20 rebar dowels provides shear connection between the structure and the culvert top slab. Dowels are installed and grouted prior to the erection of formwork. The entire kerb/diaphragm wall structure is cast as a unit. Concrete is supplied by skip from a mobile crane. Few problems were encountered with the casting. The subcontractor (L-Double) was required to complete 2 dosing line structures per day. This was never achieved. The construction proved labour and plant intensive. LLJV crews were required to assist on several occasions to avoid delays. It was also clear that the subcontractor was over committed on various other sections of the power station. A second subcontractor was employed to ensure the production of 2 units per day. The standard formwork proved useful in the construction of various special dosing line structures with only minor modifications required. These include access culverts, diversion culverts and intake unit kerbs. Refer Appendix E.2 for a summary of dosing line installations to special culverts.

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16.2.2. Pre -cast Concrete Installation The pre-cast solution is preferred for a number of reasons notably the superior concrete quality, ease of installation and efficiency of production. Ultimately the dosing line was a belated addition to the culvert structure. Each culvert is fitted with 4 no. kerb units, 2 no. diaphragm wall units and 3 no. cover slabs. The position of the structure is set out on the culvert and dowel positions marked. 16 no Dowel bars are cored and grouted to the top slab of each culvert unit. Installation was by specialist subcontractor due to the high cost of coring equipment. The pre-cast kerb and diaphragm units are placed on a layer of bedding grout and all joints grouted. Diaphragm walls are painted with anti-fouling paint to ensure the HDPE sleeves remain free of marine growth during the construction phase. 3 no. 20mm Polyrope messenger lines are placed through the diaphragms and the cover slabs placed on top. 55 No. special diaphragm walls (Type B) were cast on site together with 104 cover slabs. Pre-cast installation was initially by subcontractor. Installation of 3 sets per day was easily achieved with a single crew consisting of 1 supervisor, 3 labour and 2 riggers. Plant includes a dedicated Rough Terrain crane and small concrete mixer. The pace of installation was dictated by the placement of culverts offshore. Pre-cast installation was eventually taken over by a LLJV crew proving extremely cost effective. Refer to Appendix E.3 for the basic pre -cast installation procedure. 16.3. PIPE WORK: INSTALLATION AND FITTINGS The Dosing Line consist of 3 separate 225mm O.D. HDPE main pipes from the onshore termination point to each individual intake head unit at the offshore end of the Cooling Water Intake culvert. The hypochlorite solution is dispensed into the culverts at these points. Each pipe is installed in three sections; the Intake string, Launched string and land section. Custom designed HDPE ring pipes and Intake String pipe work was manufactured and delivered to site by specialist subcontractor. Materials are PN10 rated HDPE pipe and fittings and Grade 316L Stainless Steel for flanged conne ctions at all joints and pipe support work. The ring pipes are fitted to the Intake Head Units prior to load out for placement offshore. Supply of special HDPE ring pipe sections proved slow, mainly due to delays in supply of Grade 316L Stainless Steel for flanged connections, which was not locally available. In practice only the ring pipes were fitted prior to unit placement. Divers installed connection pipe work on the Intake Strings to as-built dimensions after placement of the culvert units. This process proved tedious in the zero visibility conditions. 16.3.1. Launching of Pipeline The main section of each dosing line is launched from an onshore launch way, through pre -installed launch sleeves and the pre-cast diaphragm walls along the length of the culvert. The poly rope messenger lines are spliced together to form three separate full- length messengers. A 12mm Steel Wire Rope intermediate messenger line is attached to the onshore end of the polyrope messenger and pulled through by winch from an offsh ore barge. The 24mm Steel Wire Rope pull line is attached to the intermediate messenger and pulled through in similar fashion. The pull line is attached to the HDPE pipe by a manufactured pulling head. Diameter 355mm HDPE launch sleeves are installed from the offshore end of the In-situ Culvert section to a suitable surface entry point adjacent to the In-situ Culvert Chimney. Each sleeve is 60m long and fitted with a 12m length of HDPE test pipe Leighton-LAMA Joint Venture

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at the offshore end. The test pipe is pulled through the launch sleeve prior to the launching operation to ensure the sleeve is free of obstruction and to pull through the messenger line to the onshore end. Problems were encountered with 2 launch sleeves with the test pieces being stuck at the offshore end. It was established that inferior pipe was used for the sleeves causing them to be deformed by the backfill material. Launching of the dosing line was slightly delayed. Dredging the overlaying material to relieve the overburden pressure eventually solved the problem. The risk involved was great, as total failure of the sleeves could prove very expensive. The pipe is launched in 48m increments. Each 48m length of pipe is pre -welded and joined to the launch string after each pull by butt fusion welding. Once the desired length has been launched the offshore end is brought to the surface and a flange welded to the end. The launched pipe is secured to the culvert by Stainless Steel Saddle clamps. The separate Intake String is installed to the relevant Intake units and secured. Connection pipes are welded to divers’ measurements to joint the main dosing line to each intake distribution ring. This process is repeated for each individual pipe. Refer to Appendix E.4 for the basic launch procedure used. 16.3.2. Land Section Once the pipelines are approved the land section is completed. Construction involved routing the individual pipes to a predetermined termination point adjacent to the Electro -chlorination building by means of standard land based pipe-laying methods. The dosing lines terminate at a purpose built junction box. 16.3.3. Pressure Testing Individual dosing lines are pressure tested to the requirements of BS 8010, Section 11. A specialist subcontractor was employed for this purpose. Poor interpretation o f test results resulted in repeating a number of pressure tests at excessive pressures. Delays and additional cost was incurred as a result. No significant leakage problems were encountered with the major concern being adequate sealing at flanged connections rather that damage to pipes during the launch and installation process. 16.4. SUGGESTED IMPROVEMENTS • •

• • •

The design of the dosing line structure should be incorporated with culvert design at an earlier stage to avoid delays and additional cost. Significant cost was incurred by coring of dowels to fit pre-cast kerbs for instance. In-situ construction proved expensive and problematic with subcontractors on short notice and tight schedule. Crews under own supervision proved much easier to control and more productive for such work. Pre-cast concrete is the preferred option and all effort should be made to incorporate these items at an earlier stage. Anchorage of pipe by tremie concrete on offshore sections is impractical as designed. This was replaced by less accurate sandbag formwork and concrete delivered by skip underwater. The quality achieved was adequate for anchorage. High quality materials such as Grade 316L Stainless Steel proved problematic due to slow delivery. Specialist items should be sourced at an early stage to create awareness of potential problems. Detailed pipe work is best pre-fitted on land to ensure quality of construction. As-built measurements of multi dimensional connections proved tedious in poor visibility underwater. Long Intake S trings proved difficult to handle in strong currents offshore.

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16.5. HUMAN RESOURCES Refer to Appendix E.5 for resource summaries for the dosing line activities. OWN LABOUR Involved in all aspects of dosing line construction to varying degrees as required in addition to the final preparation of culvert units for load out: • • • • •

Supervisor Foreman Riggers Skilled Labour Unskilled Labour

1 1 4 5 2

SUBCONTRACTORS: L-Double/STC Builders (In-situ installations): Both subcontractors used similar teams. Work includes formwork erection, rebar fixing, casting of concrete, striking of formwork, removal of rubble and moving materials to the next culvert for installation: • • • •

Foreman Carpenters Concreters General Labour

1 4 3 2

Lian Hup Yik Engineering (Pre -cast Installations): Handling, preparation and installation of pre -cast concrete for the dosing line structures: • •

Foreman Skilled labour

1 3

16.6. PLANT • • • • • • •

45 Ton Rough Terrain Crane 25 Ton Rough Terrain Crane Portable generators (2 no) Small concrete mixer Forklift Pulling Barge Barge Mounted crane

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Concrete installations, materials handling Concrete installations, materials handling General power supply Pre-cast concrete installation Materials handling (Part time only) Pipe launch, offshore installations Offshore installations, Cover slab placement

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SECTION 17. NAVIGATIONAL AID STRUCTURE 17.1. GENERAL 17.1.1. Scope This report covers the construction of the offshore Navigational Aid Structure to the requirements of the Marine Department of Malaysia 17.1.2. Background The Marine Department of Ma laysia specifies the requirement for a Navigational Aid Structure indicating the position of the submerged Cooling Water Intake Culvert. 3 No. 900mm diameter concrete spun piles support a concrete pile cap. A steel equipment platform is constructed on the pile cap supporting the light installation at the specified level of +10.5mACD. 17.2. CONSTRUCTION METHOD 17.2.1. Piling Three 1000mm diameter concrete spun piles were driven to the desired set from the Ketara Piling Barge with DGPS positioning system. The piles are raked at 1:4 slope in a triangular arrangement. 17.2.2. Temporary Works All works are carried out with the assistance of a barge -mounted crane. Electricity, plant and workspace are provided on the barge moored adjacent to the structure. Purpose made steel pile clamps are fitted to support a temporary work platform and soffit formwork for the reinforced concrete pile cap. An H-beam support frame to resist cantilever action due to the working loads connected the three piles. Standard PERI girders are supported on a steel framework to form the soffit. The entire soffit support is height adjustable by the inclusion of 6 no. steel spindle jacks for final levelling and stripping after construction. PERI formwork is utilized due to availability on site. Support beam dimensions and spacing was chosen to fit the available standard formwork materials. A plywood soffit was erected after careful levelling of the support structure by adjusting the 25ton spindle jacks. Wall forms are pre-assembled onshore for easy erection to the required geometric shape within the restricted space provided by the soffit support work. With the soffit in place the piles are cut to the required level. The hollow piles are blocked by casting a grout plug to complete the formwork. 17.2.3. Concrete Works The pile cap is cast in two stages to reduce the extent of temporary support work required. The first cast of 300mm thickness incorporates the connection to the piles. Reinforcing steel for Cast 1 is fixed by a specialist rebar team. After thorough inspection concreting is commenced. Concrete is delivered by mixer truck to the load out jetty and transferred to skips. A crane loads the skips onto a tugboat for ferrying to the offshore barge for casting. Retarded concrete is required due to the extended delivery time involved.

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The second cast rebar is fixed once Cast 1 concrete is set. Cast 2 may continue upon confirmation of 24MPa minimum strength of the Cast 1 concrete. This cast includes Stainless Steel anchor bolts for the steel superstructure. Once sufficient strength is gained the formwork is removed and supports dismantled. A third cast is required to complete a 150mm plinth for the steel superstructure. 17.2.4. Steelwork and Fittings All Steelwork is manufactured off site with special attention to corrosion protection. These include a 3,5m high steel Equipment Platform, handrails, access ladders and fender arrangement. The steel Equipment platform is fitted by crane off the “Crane Barge”. Various corrosion protection measures were specified including large galvanized sections and high quality paint systems. These were applied under factory conditions requiring repairs only on site for damage during handling and installation. High quality steel items proved expensive in general. 17.2.5. Navigational Aid Equipment The navigational aid arrangement is supplied by Jinora Corporation. It comprises various parts by Tideland Signal. • • • • •

ML-300 Solachan Marine Lantern South Cardinal Mark Radar reflector BP Solar panels Battery comple te with lockable case

The steel equipment platform supports the Navigational Aid equipment at the required level and position. Access is by cat ladder. The Navigational equipment is delivered and commissioned by specialist supplier. The Marine Department indicated further requirements including a lightning protection system, bird spikes and “spot welding” of all bolts and nuts to prevent theft by local fishermen. A small amount of ‘spares’ were handed over to the client for maintenance purposes. The ‘spares’ include lamps and photocell switches as requested by the local Marine Department. Refer Appendix F.1 for a summary of the construction of the Navigational Aid Structure. 17.3. SUGGESTED IMPROVEMENTS • •

• •

Site Measurement and fitting of Fender structure proved difficult due to the location underneath the pile cap and within the tidal zone. Construction required a dedicated work barge complete with crane. Toward the end of the project the “Crane Barge” was used for this purpose. The barge was very effective but under-utilized and expensive for this task. Such structures should be considered from the start of the project. With proper planning resources can be better utilized to include the construction of such ‘relatively’ small structures. Delays were encountered with supply of large galvanized steel items and high quality materials (i.e.: Stainless Steel 316L). Earlier consideration could minimize delays toward the end of the project. Extensive consultation with local authorities (notably the Ma rine Department) as to their requirements proved essential. This is entirely site driven and should be attended to from an early stage as response was generally slow. Inspection of the works revealed several issues not identified in meetings and this should be initiated early on.

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A Structure of this nature is required to provide long-term service to the client. The design should be simplified as far as possible for ease of maintenance and durability. The constraints of offshore construction must be accounted for, working within the tidal range always proving difficult.

17.4. PLANT • • • • •

“Crane Barge” with 80ton Crawler Crane Gantry Barge with 25ton Rough Terrain Crane Feeder boats Welding Plant Piling Barge

Leighton-LAMA Joint Venture

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