HOSPITAL CONSTRUCTION
temperature hot water (LTHW), gas, domestics, compressed air, LV, and HV, to the existing hospital site. Prefabricating the new pipework sections allows the break-ins into the existing steam and heating infrastructure to be undertaken much more quickly than had a traditional approach been adopted, meaning reduced downtime for the hospital estate. The new energy centre houses major plant and equipment, including three new steam boilers, each weighing 30 tonnes, a new 40-tonne CHP generation plant, two new 2 MW generators, and 40 tonnes of water storage. This heavy plant and equipment meant that the new energy centre foundation had to be seriously reinforced and large enough to cope with the load.
The team had to form two new underground service tunnels, each one 3 m wide by 3 m deep and around 120 metres long, to house all the new services infrastructure that will connect the existing hospital estate into the new energy centre. These tunnels involved deep ground excavations in order to form the reinforced concrete structures.
Modules factory-produced While the new service tunnels were being formed, NG Bailey’s offsite team was busy manufacturing all the new services infrastructure modules in the factory.
Key project statistics
n 35,000 tonnes of spoil earth removed. n 2,500 m2
of concrete used.
n 200 tonnes of equipment. n 180 tonnes of steel structure. n 12,000 metres of LV sub-mains. n 68 planned shutdowns to transfer from the existing to the new supplies. n 2 x 2,500 kVA generators to provide N+1 emergency power, serving six new sub-stations via 1.4 km of new 2,500 Amp busbar.
n 1 x 1,750 kVA combined heat and power unit (CHP). n Three steam boilers, producing 5,600 kg of steam per hour. n Installed water tanks storing 220,000 litres of water. n Installed oil tanks storing 80,000 litres of oil.
Design team: P+HS Architects; RPS Structures & MEP.
The Heavy Duty Service Modules were delivered to site immediately upon completion of the tunnel structures, and installed in a fraction of the time. Upon completion of the new electrical sub-stations, the team installed 12,000 m of sub-mains cabling to re-feed the entire site’s electrical distribution, and has undertaken 68 complex electrical changeovers of supplies. Each of the three new steam boilers measure 6 m in length and 3 m in diameter, so at 30 tonnes each these posed a significant challenge to the installation team. The boilers were delivered and craned onto a landing platform, and then had to be
carefully winched into position by specialist installation teams. The offsite team also manufactured most of the high-level services distribution components, and some of these services modules weighed as much as six tonnes, so these had to be carefully lifted and fixed into location. The two new electrical generators are each sized to accommodate the entire site’s essential load; at 2.5 MW each they are some of the largest types manufactured. To connect the new generators into the site-wide electrical infrastructure, the site team has installed over 1.4 km of electrical bus bars within the new service tunnels.
February 2019 Health Estate Journal 53
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