Draft Overview of HPC Construction - EDF Hinkley Point

vehicle usage and estimated traffic volumes. These haulage roads would be surfacedwith tarmac or compacted granular material as appropriate, and the surface waterdrainage would be tied into the construction drainage systems to be installed duringthe site preparation works.4.1.38 Lighting will be provided along the haulage roads in line with the lighting strategy. tobe submitted with the application for Development Consent. This will ensuresufficient lighting levels for safety whilst minimising stray light and adverse visualimpact from off-site viewpoints.g) Civils Worksi. Introduction4.1.39 The civil works will pick up from the site preparation works, completing the deepexcavations before starting the building construction.ii. Platform Development and Deep Excavation4.1.40 Most of the platform development and ground terracing will have been undertakenduring the site preparation works. However, as the deep excavations areundertaken, additional platforms and access routes will be required to facilitateaccess. The deep excavations will involve mainly fresh rock, although someweathered rock will be encountered. Where practicable, mechanical excavation willbe used. However, blasting may be required and this will be strictly controlled, withappropriate warning given to nearby residents. The excavated material will betransported to the designated stockpiles in the south of the site.4.1.41 Excavations for unit 2 and the interim spent fuel store will continue after theexcavations for unit 1 are complete and construction of the unit 1 buildings areunderway.4.1.42 Backfilling of the excavations as the buildings are constructed will be managed inaccordance with strict EDF Energy requirements. Different material standards areapplied depending on the location and performance required of the backfill. Wherepracticable, excavated material will be used for backfill and this will require carefulquality control in the segregation of materials going to the stockpiles. To achieve theparticle size standards required for backfill, rock crushing plant will be used. Whereexcavated material is insufficient or unsuitable for backfill, appropriate granular fillmaterial will be imported.iii. Surface Water and Groundwater Drainage4.1.43 The construction drainage system, which will be installed during the preliminaryworks, will handle the surface run-off and groundwater flows associated with thevarious platforms. This system will be extended to enable drainage of the deepexcavations using dewatering wells. The nature of the underlying geology indicatesthat the additional groundwater flows will be limited and predictable. However,monitoring will be carried out to measure the water quantities and quality such thatappropriate controls can be implemented as necessary.4.1.44 As part of the civil works, permanent site drainage systems will be installed. In someareas, the permanent systems will utilise parts of the construction drainage22 DRAFT | Overview of HPC Construction | February 2011