080731 6LYG A1 Particular Tunnelling Specification ... - SCATnow

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Lee Tunnel, Contract No. 6LYG/A1 PT – Particular Tunnelling Specification - PT200 identify any trends in readings that demonstrate that ground movements are in accordance with predictions and control of the stability of Works. PT241.19 The Contractor shall observe, record and analyse the readings in a monitoring report to establish trends in movement and shall provide a copy of all recorded results to the Project Manager. He shall make available results to the Project Manager in accordance with an agreed programme. PT241.20 The format of reporting of monitoring results is to be agreed with the Project Manager prior to commencing construction activities. Typically it is to contain: a) Graphical representation of settlement of buildings/ground over time and annotated with tunnel / excavation progress. b) Excavation data including material excavated. c) Settlement and excavation data trends. PT241.21 Hard copy results of the settlement arrays or monitoring points are to be made available to the Project Manager on a daily basis when the tunnel face is within 25m of the array and weekly thereafter in excel and pdf format. PT241.22 Monitoring of settlement, scheduled defects and defects arising during the course of the Works shall continue at agreed intervals for a period at least until the end of the defects date or other such time as agreed by the Project Manager. PT242 PT242.1 PT242.2 PT243 PT243.1 PT243.2 PT244 PT244.1 DEFECT AND CONDITION SURVEYS Pre and post construction defect surveys shall be carried out to a programme and methodology as submitted to and agreed with the Project Manager for all structures and key utilities identified as being within the 5mm settlement contour as shown on drawings 6LYG-A1-02131 to 02141. The Northern Outfall Sewer (NOS) The Lee Tunnel alignment follows the route of the existing Northern Outfall Sewer (NOS) for approx 4.5kms. The Contractor shall carry out a visual Condition survey of the sewer as soon as practical after the award of Contract. Record drawings of the sewer are included in the Contract for information (Section 6). The survey shall be organised by the Project Manager in liaison with the Thames Water Operations Division who will provide all safety cover and review Method Statements for the survey as required by the Thames Water procedures for Entry into Confined Spaces and Live Sewers. The Contractor shall provide a Northern Outfall Sewer Condition Survey Report which shall be submitted to the Project Manager who, in liaison with the Contractor, will agree any protective measures to the NOS that will have to be carried out. TEMPORARY ELECTRICITY SUPPLY FOR TUNNEL CONSTRUCTION The Employer has agreed to make available a supply of electricity to the Contractor for the Construction of the Works. Details of the proposed supply are described in Schedule 3 Clause 4 of the Works Information. The Contractor shall confirm that the supply will be in accordance with his specific requirements. If the supply is insufficient the Contractor shall make his own arrangements for the provision of alternative additional power requirements. Emergency Generator: Supply an emergency standby generator of such capacity and configuration as to automatically and instantly come on line in the event of a power failure, without interruption, and to operate ventilation, lighting, pumping, communications and other critical systems. TREATMENT OF ARISINGS Spoil Processing requirements for Slurry TBM Thames Water Utilities Limited August 2008 Page 34 of 38
Lee Tunnel, Contract No. 6LYG/A1 PT – Particular Tunnelling Specification - PT200 a) The Contractor is responsible for the design of the slurry separation plant, and shall comply with the MINIMUM requirements as set out below. The Contractor shall take account in the design of his plant the materials to be excavated in the Graben structure as defined in the Geotechnical Baseline Report (GBR). Details of the design shall be submitted to the Project Manager for acceptance within 28 days of contract award. b) The Separation Plant shall have the capacity of processing 300 cu.m. of solid excavation material per hour. The centrifuges shall have the capacity for processing 200 cu.m. per hour of chalk fines and the removal of all particles above 5 microns in size. c) The moisture content of the slurry paste for disposal shall not exceed 45% unless agreed otherwise with the Project Manager. PT244.2 PT244.3 PT244.4 PT244.5 PT244.6 PT244.7 Spoil Processing requirements for EPB a) The moisture content of the material for disposal shall not exceed 45% unless agreed otherwise with the Project Manager Wastewater can be disposed of as follows: a) The wastewater from the slurry separation plant can be discharged into the chamber, adjacent to the Work Site, as shown on Drg 6LYG-A1-02208A from which it will discharge to the to the Head of the works in Beckton STW. The Contractor shall be responsible for maintaining the discharge pipe in good working order. The wastewater shall not exceed the following criteria, and testing samples shall be submitted weekly to the Project Manager, for analysis by Thames Waters’ Operations team:- i) Suspended Solids - 750 mg/l ii) COD - 375 mg/l iii) Ammonia - 25 mg/l iv) Sulphate - 1400 mg/l b) For water not meeting the criteria in (a) above, the water will be disposed of offsite, in agreement with the Project Manager. The Contractor shall allow for processed spoil for disposal to be delivered by conveyor to the start of the jetty bridge as shown on Drg 6LGY-A1-02208. The conveyor shall be capable of transporting a minimum of 400 cu.m.of spoil per hour. The location for barge loading is identified on Drg 6LGY-A1-02208. The Contractor shall manage the logistics of river transportation of other materials to be delivered to the jetty bridge. (refer to ITT). The Separation Plant shall be new and purchased for the Project. The Contractor shall, using similar materials to those identified in the GBR for the tunnel alignment, conduct trials to demonstrate to the satisfaction of the Project Manager prior to purchasing the separation plant that it can meet the requirements above. Storage of Excavated Material, both EPBM and SPBM 2 no. existing sludge tanks (approximately 4000m3 storage volume each) as shown on Drg 6LYG-A1-02208A can be made available to the contractor for storage of excavated material, if required by the Contractor. These tanks currently store sludge and the initial emptying and cleaning of these tanks shall be under a Provisional Sum Thames Water Utilities Limited August 2008 Page 35 of 38
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080731 6LYG A1 Particular Tunnelling Specification ... - SCATnow

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