MODERN METHODS OF CONSTRUCTION


The new building has an increased number of treatment rooms. All the internal spaces were designed to be light and airy.


suitable space available on the Derriford Hospital site. The site formerly housed a Royal Marines barracks, believed to have been demolished in the late 1990s. Paul Williams explained: “We didn’t have floorplans, so we didn’t initially know where the new building would sit. On digging trial holes we discovered some old basements and stair cores. With the location leased from Plymouth City Council, and not on a hospital site, we liaised closely with Council planners throughout; they had considerable input.”


Initial groundworks MTX began its initial groundworks in February 2022 with a reduced level dig to get to the foundations, a couple of metres lower than the existing ground. Paul Williams said: “Within that phase we hit some remnants of previous buildings which we had to get rid of. We came across three or four rock seams quite low down, which caused delays, because the rocks were extremely strong, and we had to bring in large machines to break them down. The planners wanted us to build lower, and the deeper we went, the more rock we hit.” He added: “We found what we think


were the bases of MOT inspection bays. Some of the areas were contaminated, so we had to address that, including via sampling. In the end the groundworks took until August 2022 to complete – including 4-5 weeks of delay due to the ground conditions.” For the foundations of the new building, MTX used a cast slab across the whole base. Paul Williams explained: “The volumetric


units we put in were floorless. We also installed a large 200 metre retaining wall on the sloping site. At the far end, where we cut down two metres, we installed 2-metre-wide concrete rings to provide additional support and backfilled in between. We based our foundations on the specific ground conditions and slope.” In all 112 volumetric units were used to


create the new building. The MTX site team was able to make use of an adjoining empty site, rented from the Council, to store the modules, while groundworks


42 Health Estate Journal June 2024


continued. Over a 21-day period in September 2022, the volumetric modules were lifted into position. Paul Williams added: “Without the wet weather delays, we’d have got the building watertight in peak summer, but dealing with the rock seams pushed everything back, and the primary build time became winter, rather than summer. It was challenging, because we then had biblical amounts of rain to contend with right through from September into November.” “After 21 days,” he continued, “we were


watertight, and had the shell. The internal floors come with a hollow Lewis steel rib deck, onto which we applied a liquid screed. This project used volumetric empty units fitted together with traditional concrete floors and then fitted out on site.” Gill Nicholson said: “There are specific ophthalmology microscopes in the new theatres, bolted into a steel frame, rather than attached to the building. There were specific vibration requirements; the vibration factor here is 1. While there will be some vibrations, they won’t impact theatre activity because of the structure and design.” Paul Williams added that due to the use of the Lewis deck, the vibration factor on the upper floors would be the same as in the ground floor theatres. The ‘complex’ building services work undertaken by MTX included installing three roof-mounted air source heat pumps, which at the time of design, Paul Williams believes, were the biggest Mitsubishi had ever provided in the UK. He said: “We specified air source heat pumps as a design team, looking at their heating capabilities and what’s required, the Building Regulations, and working with Plymouth City Council on future- proofing the building for its potential use as part of a district heating system. The air source heat pumps, housed in a louvred enclosure, are energy-saving, and their use means there is no gas going into the building. They are supplemented by back- up heat exchangers and calorifiers.” The second floor plantroom houses six air-handling units – one per theatre, and the others serving the building’s common areas. The new Energy Centre houses an


HV transformer, and LV electrical plant, plus a medical gas enclosure, a water tank room, and a refuse room. Paul Williams explained: “We have trenches running underneath for the gases and cables, which come up the back of the lift shaft, over the roof, and into the plantroom.” Each theatre receives 20 air changes / hour, with the rest of the building receiving 6-8. In line with the Trust’s Net Zero aspirations, there are photovoltaic solar panels on the roof.


Theatre equipment Gill Nicholson said: “The theatre equipment is state-of-the-art; our existing Zeiss microscopes are fitted to the roof of two theatres. We also have a standing microscope for the third. Because ophthalmology is such a specialist field, a lot of other equipment came across.” I asked what she felt had been the


key challenges for her in managing the project. She said: “COVID has changed our pathways dramatically. With risk stratification pathways, we are now moving towards a diagnostic service, with a lot of Ophthalmology now ‘one-stop’. I think that’s changed healthcare across the board over the last three years. We’ve had to look at the original designs for the new building created pre-COVID, and then re-look at them and the new pathways post-pandemic. “Equally,” she said, “I’m not a builder, so


for me it’s been about understanding that there’s different languages, and between ourselves and MTX we’ve had to take that working relationship forward smoothly. Working with the site team, my team and I learned a lot, and we navigated any obstacles to come out the other side with a fantastic building.” Paul Williams explained that the project


was at one point around six weeks behind schedule, but got back on track and completed with handover in time for the October opening. He explained: “For us – apart from not knowing what we’d find in the ground – the biggest challenge was material and staff shortages, a consequence of COVID, and not things you can really plan for.”


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