Water and Effluent Treatment Magazine
Issue link: https://fhpublishing.uberflip.com/i/538666
JULY 2015 WET NEWS 15 A s building started, unrestricted access to the project site should have allowed construction to work outwards from the furthest point from the access route. However, the programme required early installation of the thermal hydrolysis plant and the base for it was made available first so that Veolia could proceed with its erection and installation whilst civil work continued on adjacent slabs. "Our construction area was located adjacent to the existing plant within a small footprint and with only one main access route," says Veolia's project manager, Paul Sall. "This meant that the plant had to be installed starting at the furthest point and working back towards the main access point." Hazards With so much going on, AKT held daily health and safety briefings with all the contractors to ensure that all operatives on site were aware of the activities planned for the day and any particular hazards. "We also provided safety inductions and toolbox talks to all our subcontractors and liaised on a daily basis with AKT so that all were aware of all material deliveries to ensure safe traffic management and off- loading," says Sall. "The main contractors and subcontractors cooperated fully to draw up daily plans for areas where construction vehicles and cranes were being used." Sall's team included a full- time site manager and a full- time site supervisor overseeing subcontractors for steelwork erection, pipework installation and lagging and electrical installation. Inevitably, there was overlap between the subcontractors working within the thermal hydrolysis plant area, barriers with appropriate warning signs were erected to ensure segregation and maintain safe working. "At times, AKT required that no other personnel should be on our plant slab when pressure testing was being carried out," says Sall. "We coordinated this by either conducting the tests out of normal working hours or re-scheduling lunch breaks." A solution: It's good to talk Cooperation among the project's teams ensured the project went full steam ahead, says Tim Humphreys. The verdict In spite of the many challenges of the scheme, good project management, BIM planning and strong site management meant an exemplary health and safety record during the erection, installation and initial commissioning phases of our installation. 25,000 man hours were expended for the Veolia THP Plant – all of which was accident free" Lyndsey Wicks, Veolia • Complex project • Main contractors and large number of subcontractors on site • Restricted site • High temperature and pressure process plant • No health and safety accidents The Biothelys plant installation (top) was completed in accordance with the 3D model (bottom) Plans were drawn up daily for areas where construction vehicles and cranes were being used Need To kNow 1 Building information modelling (BIM) is a crucial tool for project management 2 3D modelling improves project planning 3 Cooperation between subcontractors is essential 4 The principal contractor's role in communication is vital to site health and safety 5 Installation and commissioning of thermal hydrolysis plant completed whilst other construction work continued The Biothelys plant installation was completed in accordance with the 3D model. Risk assessment From the initial start date, commissioning began a year aŽer with dry and wet testing followed by statutory inspection by Thames Water's insurers. Risk assessments identified a number of specific health and safety issues associated with commissioning that were exacerbated by the fact that building of the sludge handling plant was still in progress. A safe system of work was agreed including pre-start workshops, daily start of shiŽ briefings, working area segregation by temporary fencing and blue bibs for those with permitted access. The thermal hydrolysis process conditions necessitated a separate induction, enhanced work permitting and specific training for all for those working with steam. Commissioning with steam, at up to 13.5barg, was undertaken in a sequential manner to ensure the integrity of all vessels and associated piping through initial warm-up at low pressure. Only aŽer checking for leaks and pipe movement was steam pressure increased. Finally, water was introduced into the pressure vessels and heated to operating temperature by live steam injection. n Tim Humphreys is head of Projects at Veolia Water Technologies. The Biothelys plant installation was completed in accordance with the 3D model (bottom right) The coNcepT