Morgan Ashurst is shoehorning a new Pharmacy and Bio-molecular Science facility into a tight footprint at the University of Brighton’s Moulsecoomb campus. By Paul Thompson
Scheme: New Pharmacy and Bio-Molecular Science building
Client:University of Brighton
Main Contractor:Morgan Ashurst
Form of contract: JCT 2005 Design & Build
Contract value: £17 million
Lead designer:Morgan Professional Services
Structural Engineer:Gyoury Self
Clients lead consultant:McBains Cooper
Demolition sub-contractor:Dorton Engineering
Piling sub-contractor:Foundation Piling
Concrete frame sub-contractor: MJ Gallagher
Groundworks sub-contractor: Natta
The University of Brighton, the former Brighton Polytechnic, is building on its status as a well recognised seat of learning and redeveloping a corner of its Moulsecoomb campus on the north eastern outskirts of the town.
Students have been offered degrees in pharmacy and applied sciences at the campus since its origin as Brighton College of Technology and now the university is updating its facilities by building the new Pharmacy and Bio-Molecular Science block at the site.
Morgan Ashurst project manager David Goulden, one of a dozen members of the current management team who were construction students at the University, is the man charged with bringing the £17 million contract to completion within its 94 week time frame. He is well versed with the complexity of this type of building, even one where there is precious little room for manoeuvre such as the Brighton project.
The site is hemmed in on all sides by a series of access roads, existing university buildings and the railway line that helps link the Moulsecoomb station to Brighton’s main centre. With these existing buildings set to remain in use throughout the construction period the project team has been using two Potain saddle back tower cranes to distribute materials around the site of the six storey building.
“Logistically it has been difficult,” says Mr Goulden, “basically the building’s footprint is the site so there is not that much room. We have had two tower cranes on site. One working within the building the other outside. The first will be decommissioned in a month or so the other will be here a little longer.”
So cramped is the site that Mr Goulden admits without two temporary loading bays designed by scaffolding contract south London based D&R Scaffolding, the team would have been struggling to build the project.
“We introduced the loading bays – there is a 20 tonne bay on top of the cabin – and they are monitored on a weekly basis. To be honest without these two areas we would have found it very difficult,” he says.
Those cranes were not allowed to oversail the track and were sited working closely with rail network provider Network Rail. The close proximity of the site to the line, coupled with the removal of a retaining wall at the foot of the embankment as it passes alongside the campus meant that the crane bases and piles were overdesigned by a factor of as much as 25 per cent to meet Network Rail’s stringent safety requirements which included one of its supervisors being on-site during the work.
Controls for the two tower cranes can be switched either from the cab or the ground enabling the driver to bank the lifts from ground level. At the same time a further hoist installed alongside the reinforced concrete frame is helping Morgan Ashurst’s concrete contractor MJ Gallagher, bring the frame in on time.
“The key is getting exactly what is needed on that floor plate when it is needed. The reinforcement is delivered on a just in time basis and is procured on a strict cycle,” says Mr Goulden.
By keeping close control over the delivery of the reinforced concrete frame the project team has been able to move the critical path forward, essential when the work programme is so tight.
Sitting on a raft of more than 300 piles there was never a moment when other framing systems were considered for the scheme. The low level of vibration needed to enable university researchers and students carry out sensitive experiments ruled out the use of steel. And the short lead in time following a major re-jig of the mechanical and electrical services throughout the project ruled out precast concrete systems.
“The only place where we have any precast concrete is the stairs. We did look at post-tensioning for the huge 16 m spans in the lecture theatre, but in the end we designed the need out by using low heat concrete,” explains Mr Goulden.
And despite the fact that the use of this concrete means the formwork needs to be propped for longer as it sets more slowly thanks to the reduced heat of hydration – the concrete’s rise in temperature as a result of the chemical reaction within the mix – the team have been able to stick closely to the work programme.
Thankfully for the project team despite the site being located directly opposite a student hall of residence, the local authority showed the university’s undergraduates no mercy and afforded unrestricted working hours on the project – enabling the team to work six day weeks and ruin the lie-in potential for students in the halls.
But another key design decision has also helped keep the project on-track. By dropping the use of masonry for the inner walls and using the Metsec steel framing system, Morgan Ashurst has speeded up the construction process. Fixed on site to form a lightweight steel cold rolled framework, the system enables the external cladding to be placed quickly, making the building itself weatherproof. This has enabled the finishing trades to get on site earlier than expected.
“The building features a steel mansard sedum roof and is clad using Schüco panels. We took the decision that having an internal blockwork skin on the building could not be done as an item on the critical path. By using the Metsec framework we are able to get the building 95 per cent watertight almost immediately. We are commissioning the fit-out works three weeks earlier than we normally would do,” says Mr Goulden.
The team is focused on delivering a finished building ranked ‘Very Good’ under the BREEAM environmental assessment scheme, a rating which is pretty much on the environmental limit of what can be built for laboratory and science establishments, Mr Goulden claims.
“We have tailored the design as much as is possible, there are new boilers and now solar panels but I think the building is about as green as potentially and economically it can be,” he says.
Ultimately though this is a building that will deliver against all of the items on the client’s wish list and looks well on course for its February 2010 completion date. Then the University of Brighton will have another facility with which to promote its burgeoning reputation.
Piling into chalk no bar for Kelly system
With some 313 piles of 450 mm diameter bearing onto the underlying chalk strata and holding up the new building the piling, groundwork and bulk excavation was always going to be key to its successful delivery.
One area that troubled the team was that thanks to the varying basement levels compared to the existing site earthwork, sub-contractor Natta faced the awkward task of digging around a forest of piles that needed to be broken down to formation level from piling mat level. But subcontractor Foundation Piling ensured the team was able to cast piles from existing ground levels to a level just above final formation level, negating the need for expensive and time consuming pile trimming. It also allowed the bulk earthworks to be carried out more efficiently.
“The Kelly bar method is similar to a continuous flight auger piling arrangement but the auger is only around 2 m long,” explains Morgan Ashurst project manager Dave Goulden, “This allows you to bore piles through the ground and terminate the concrete pour so that the cast piles are almost exactly at the required depth. There were places where the piles were only overcast by around 500 mm. You do get a bit twitchy as they are being unearthed but it is that level of accuracy that helps create less waste and speed up the whole excavation, piling and earthworks process.”
More than 4,000 cu m of spoil was removed from the site during earthworks with around 2,000 cu m of clean chalk stockpiled for backfilling.
Mechanical and electrical brain storm
The concept design for the project had intended for it to be built in two stages and this showed in the layout of the specialist HVAC and mechanical and electrical services. When Morgan Ashurst brought in its sister company Morgan Professional Services as specialist laboratory planning engineer to the project, the MPS team immediately set out a reviewing and reworking the existing concept design to provide a better and more efficient layout using 3-D computer modelling techniques.
This included remodelling the services distribution and plant room accommodation as well as rationalising the layout of the fume cupboards and their ventilation throughout the building.
“Initially, flue extractors were sited along the top of the building’s roof, but results from our tests showed that fumes would drift across to other buildings on the campus. We have redesigned the layout of the fume cupboards within the building and the 1 m diameter ducts that vent the fumes through two extracts to the western end of the building,” says MPS design manager Geoff Pester.