SIEA LUNGGA POWER STATION RETAINING WALL

Transcription

1 SIEA LUNGGA POWER STATION RETAINING WALL

2 1. Glossary In this scope of work the following abbreviations and definitions apply. Term AS 3000 AS 3600 AS 3700 Boundary Lines AS 4678 Brick Works Contract Contractor Scope of Work SIEA SIEA Site Representative Tenderer UXO Works Meaning Australian Standard for Electrical Installation Australian Standard for Concrete Structures Australian Standard for Masonry Structures The official line that divide one land from another Australian Standard for Earth Retaining Wall Wall construction using concrete blocks Terms of agreement under which the Scope of Work is completed. The Scope of Work forms part of the Contract Qualified party awarded the Contract to carry out the Works As provided in this document Solomon Islands Electricity Authority SIEA nominated project manager or project engineer Respondent to SIEA request for quotation on the Works Unexploded Ordinance The work to be carried out under the contract 1

3 2. Table of Contents 1. Glossary Table of Contents Introduction Background Scope Overview Scope of Work Basis of Design Battery Limits Concurrent Works Design Scope Documentation: Site Preparation/Excavation Foundation Soils Footings Backfill Retaining Wall Drainage Demolition and Re-erection of Fence Supply Scope Earthing Work Excluded UXO Schedule General Requirements Service Conditions Quality Assurance Packing and Transport Tender Requirements Mandatory Site Inspection Evaluation Criteria Concept Design

4 6.4. Tender Schedules Commercial Terms Appendices Appendix A Boundary Line Appendix B - Schedules Appendix C SIEA Permits Appendix D Boundary and Proposed Wall Site

5 3. Introduction 3.1. Background The Solomon Islands Electricity Authority (SIEA) is currently undertaking a major upgrade of the facilities at Lungga Power Station in Honiara. These works include: The construction of a new power station; installation of a new high voltage transformer and large capacity water tank for firefighting purposes. It has been identified that the construction of a retaining wall is also required to maintain a desired ground level for the new power station facility. Aerial view and boundary line of Lungga Power Station. See Appendix D for boundary line. 4

6 3.2. Scope Overview The intention of this document is to provide sufficient detail for suitably qualified and competent parties to design, supply materials and construct a retaining wall at Lungga Power Station, the Works. With reference to the requirements detailed in this specification, the party awarded the contract will carry out the following: Design a retaining wall, security fence and drainage including interfacing with existing and proposed planned infrastructure. Supply drawings and calculations for review Build the retaining wall. Construct drainage. Pull down the existing fence along the site for the retaining wall and store materials safely for possible future use.. Re-erect the fence on the top of the retaining wall using both recovered and new materials Install bollards to protect the fence. Supply materials for construction. Provide survey details and finishing levels. Re-route the existing oil separator outlet pipe. Backfill the area between the oily water separator and the fuel day tanks up to site level (Shown in Appendix D yellow) Site clean-up after the project. 5

7 4. Scope of Work 4.1. Basis of Design The proposed retaining wall site is included in Appendix A of this specification. The scope includes the design of an approved retaining wall; supply of materials; demolition and reerection of fence; installing bollards; constructing retaining wall and drainage; and supply materials, drawings and survey details. The purpose of this retaining wall is to maintain a consistent finished level outside the east side of the new power house. The level is necessary to have enough access space to work on the new power house building and for the construction of some structures which are to be attached to the new power house. The length of the retaining wall is around 95 metres (to be confirmed by the Tenderer before submission of the tender response). The wall will be built just inside and along the boundary as shown below and in Appendix D. The Boundary line runs along the coordinates ( , ) to ( , ). The figure above shows the proposed site for the retaining wall and the fence to be removed. 6

8 4.2. Battery Limits The battery limits are: Battery Limit The Power Station boundary The interface between the drain at the retaining wall base and the proposed culvert at the front gate. The interface between the drain at the retaining wall base and the drainage system at the South East corner of the site. The interface between the retaining wall and the main entrance gate. The interface between finished surface on the power station east end and the retaining wall. Existing 11kV pole Existing site office Existing guard house The Power Station earthing grid Contractor Interface The retaining wall shall be completed inside the Power Station Boundary The Contractor shall design and construct a drain at the base of the wall that interfaces with the drain at the base Power Station gate and the proposed culvert across the gate. The Contractor shall design and construct a drain at the base of the wall that interfaces with the drainage system in the South East corner of the Power Station site. The Contractor shall design and construct a suitable transition from the boundary fence on top of the retaining wall to the existing Power Station Gate. Contractor to ensure that a 1:100 fall is achieved from the power station finished level to the retaining wall. The Contractor shall design and construct the wall, fill, pavement and appropriate drainage to allow suitable rainwater drainage. To be removed by SIEA To be removed by a yet to be identified contractor To be remain. The contractor shall bond all metallic parts of the construction to the Power Station earth grid Concurrent Works There are concurrent works happening at Lungga Power Station which includes: New power station (Power Station Expansion Project) Installation of high voltage power transformer Large capacity water tanks for fire fighting purposes Drainage Works Fuel unloading bay The projects at Lungga power station is concurrently happening because of the new 10MW Power facility which is underway and is expected to be completed later this year. The Contractor is required to work with the Power Station Expansion Project team to ensure that no delays are caused to that project. The Power Station Expansion Project is not expected to conflict with the Works, but that project will have priority. The Contractor shall incorporate two drainage outlet pipes that will be installed by the power station contractor. Please note that Lungga Power Station is an operating power station. The Contractor will be required to complete a site induction and follow the SIEA safety processes (Appendix C). 7

9 4.4. Design Scope The Contractor responsibility includes one or more site visits to confirm the dimensions, as well as the design and calculation necessary to meet the requirements expected to construct the retaining wall. The SIEA site representative will consider deviations from the Scope of Work if the tenderer can demonstrate that the deviation is fit for purpose and best for project, however it must be in accordance with the Australian Standard Documentation: The Contractor shall prepare the following documentation for review: Basis of design document clearly stating all design assumptions. Site general arrangement showing wall location and underground services including the new power station equipment including oil equipment, radiators and septic tank. Retaining wall typical cross section Retaining wall calculations Drain levels Drain typical cross sections Drain interface details Fence installation details Earthing details Bollard / safety rail installation details Construction notes including all relevant construction specifications (Drawing notes to include construction requirements including tolerances and specific requirements from AS 4678.)Inspection and Test Plan As built drawings from site survey carried out by the Contractor Contractor to recommend maintenance and performance monitoring of the wall Site Preparation/Excavation Excavation shall include the removal and disposal of all materials necessary for the construction of the retaining wall Contractor shall verify locations of existing structures and utilities prior to excavation. Foundation soil shall be witnessed by SIEA site representative to ensure that the actual foundation soil strength meets the specified design strength. Over-excavated areas shall be filled with compacted backfill. Soil not meeting the specification in the design shall be removed and replaced with an acceptable material. 8

10 Foundation Soils The foundation sub-grade shall be compacted to provide approximately uniform subgrade stiffness and required bearing capacity. Soft spots shall be removed and replaced with suitable fill Footings A reinforced concrete pad or footing shall be in placed to provide a firm level surface to facilitate the erection of the retaining wall. SIEA site representative to witness reinforce work and slump test of the concrete prior to concrete pouring for the footings Backfill The SIEA site representative(s) shall witness on site: The type of soil use as backfill according to the contractor specification. The compaction of the backfill is compacted according to construction methodology in the construction notes specified by contractor Retaining Wall Any and all brick works shall be in accordance with AS 3700 which is under Masonry Structure. Any and all concrete walls and structures shall be in accordance with AS 3600 which is under Concrete Structure. The wall height shall reach the finishing level of the east end of the new power house allowing for a 1:100 fall. The wall is to have Weep holes, drains and appropriately designed and constructed fill to drain any surface water and avoid build-up of water pressure behind the wall in accordance with AS4678 All wall construction methodology used shall be in accordance with AS Proper care to be taken in construction of the wall including placing bricks (if required), this is to ensure straight alignment of the wall Drainage A spoon drain is to be built at the base and on the top of the wall. This shall extend along the length of the site boundary and connect to the proposed drain box culvert that will later be installed (out of scope) across the main entrance to the power station. Both drains shall be interfaced and the wall shall have weep holes and appropriate down pipes from the top drain to the bottom drain. The drain design shall incorporate a means to prevent siltation and does not lead to erosion. 9

11 4.6. Demolition and Re-erection of Fence An existing fence is in the way of this project, therefore the fence is to be removed and be relocated on the top of the proposed retaining wall. The fence is to have stainless steel razor wire installed. The Contractor is responsible for ensuring the material available is appropriate and sufficient for re-use. The Contractor shall provide any additional material required to complete the fence. If all or part of the existing drain along the fence line cannot be reused or is outside of the Power Station boundary the Contractor shall demolish and dispose of those parts Supply Scope The scope of supply is all the equipment and materials required to complete the works; including but not limited to: Concrete blocks or bricks Coronus or other suitable fill Reinforcement bars Concrete Weep hole pipes Fencing materials including galvanised pipes, mesh, wire, barbed and razor wire. Anchoring materials All other material required to complete the Works 4.8. Earthing o o o The earthing design concept is generally acceptable, but must be connected back to the site earth grid at multiple points Please take the Northpower power station design and nominate the most appropriate connection points. 70 mm square copper is acceptable; 95 mm square is preferred to match the PowerStation grid. The remainder of the power station fence should be earthed, or an isolation panel must be installed at each end of the earthed fence. The metal parts of the pumping station should be earthed. I am working with our team do design an appropriate arrangement. Stair way for SPO it was identified that SPO no longer has access from the east side of the power station because of the fuel tank location. A set of stairs behind the pumping station would relieve this issue. The site office will now be half demolished. Access should be provided between the site office and the retaining wall. To achieve this a road should be installed between the security guard and the site office. The location of the wall at the entrance needs to be defined. My current understanding is that it will follow the site boundary until it reaches a point behind the guards office the travel east behind the guard house. The design includes a drain to the site entrance. There is currently nowhere for the water to go at this point. The culvert crossing the entrance should be included. 10

12 4.9. Work Excluded The contractor is not responsible for removing any existing or operational utilities that might be in the way of the project. Upon discovering any of such services, the Contractor must liaise with SIEA site representative UXO Responsible authority to certify the site regarding the unexploded ordinances (UXO) before the works can proceed. SIEA is responsible for arranging the clearance Schedule The contractor must provide a proposed schedule of work and milestone payments schedule as part of their quotation. As a minimum requirement the schedule shall include the date and durations of the following tasks: Procurement of major items; Site clearance and excavation; Steel and formwork works Wall Construction Erecting fencing Drainage work Completion date 11

13 5. General Requirements 5.1. Service Conditions The retaining wall shall be capable of withstanding the worst environmental conditions likely to be encountered at Lungga power station. The following condition details the environmental conditions to be considered for the works: Ambient temperature range Max. relative humidity 99% Rainfall range Maximum wind speed Corrosion protection Structure design life Maximum Vehicle Loading Earthquake Actions 24 to 34 degrees C 66 to 187 mm/month 200 km/h Coastal aggressive 100 years 20 tonne Earthquake actions shall be evaluated in accordance with NZS , Structural design actions Part 5: Earthquake actions New Zealand except for the following provisions: The hazard factor (Z) shall be 0.36; The return period factor, Ru for the ultimate limit state shall be 1.3; and The return period factor, Rs for the serviceability limit state shall be These are on based that the importance level of the power-generating facilities is 3 and the historic recorded earthquake magnitudes for Honiara are up to 8.1. Lungga Power Station is approximately 10 kilometres from Honiara. The hazard factor for New Zealand shown in Tables 3.3 and 3.4 and Figures 3.3 and 3.4 of NZS shall be disregarded Quality Assurance The Contractor shall submit a quality management plan with proposed inspections. This shall, include the relevant standards to which they will conform and expected dates of inspections to be witnessed by SIEA s representative. The Contractor shall be fully responsible for ensuring and continuously monitoring that the quality procedures and practices are fully compatible with the requirements of their quality plan. 12

14 5.3. Packing and Transport All Contractor supplied items or materials should be appropriately packed and delivered to site. Any damage to equipment during transport and installation will be the responsibility of the Contractor. 13

15 6. Tender Requirements 6.1. Mandatory Site Inspection Part of the tender process is a mandatory site inspection. The intent of the site inspection is for the tenderers to inspect the proposed location and take any measurements required for procurement. The date and time of the site inspection will be on 10AM on Wednesday, April 8, Evaluation Criteria The key criteria that will be assessed in selecting a contractor to carry out this work will be as follows: Demonstration of the ability to carry out the design to the specified standards (40%); Demonstration of the Tenderer s experience carrying out similar work (30%); Safety as part of the contractor s priority (10%); Clarity of submitted documentation (10%); and Price and value for money (10%) Concept Design As part of the Tender, the contractor shall provide: A draft basis of design document detailing all the design assumptions, the method of construction and the materials the contractor is planning to use A draft and indicative retaining wall design typical cross section 6.4. Tender Schedules The Tenderer must complete the schedules in Appendix B. Please contact Gordon Lui (30309 or ; gordon.lui@siea.com.sb) for any assistance completing the schedules Commercial Terms The work will be completed under the SIEA standard terms of agreement. The Contract will include a bonus of 5 % of the contract price per week that the Contractor finishes ahead of the agreed schedule (capped at 10%) and delay damages of 5 % of the contract price per week that the Contractor finishes late (capped at 20 %). 14

16 7. Appendices Appendix A Boundary Line Proposed Retaining Wall 15

17 Appendix B - Schedules 16

18 Appendix C SIEA Permits 17

19 Appendix D Boundary and Proposed Wall Site 18