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Subtracting the Maths Tower

DEMOLITION

The Maths Tower at the University of Manchester is one of the city's tallest buildings and one of the least loved.Now, thanks to local demolition firm Connell Brothers, it will soon be subtracted from the skyline.

Alasdair Reisner reports

THERE is no small irony in the fact that a building that has stood for the past 36 years as a hotbed for the study of some of the most complex equations known to mathematics should be consigned to history by a simple act of addition.

It was the merger last October of the University of Manchester and UMIST to form a single university that signed the death warrant of one of the city's most famous yet least cherished landmarks.

The unsightly design of the Maths Tower on Oxford Road is said to be based on that of a slide rule. But, like the slide rule in an era of calculators and computers, the Maths Tower has become obsolete.With £300 million to be spent revamping the campus over the next decade, the tower site has been earmarked for redevelopment.

The responsibility for bringing down the tower has fallen to Connell Brothers, a firm with a CV dotted with high-profile jobs in the city.

Following the IRA bomb in the city centre in 1996, the firm brought down the Marks & Spencer store that bore the brunt of the blast. Since then, it has also knocked down the iconic Hacienda nightclub and flattened former Manchester City ground Maine Road last year.

Yet the Maths Tower project might presents the firm's largest challenge to date.Not only is it the 18-storey, 75 m-tower the tallest building ever demolished in the city, but its irregular profile means that scaffolding the building is a trial in itself.

Add to this the obvious issues of working at height and the fact that the demolition has to be carried out slap bang in the middle of a campus of more than 30,000 students without causing any disruption.

Site manager Mick Dowling explains: 'At the moment things are quiet because the students are away but in a few weeks, when everyone comes back, it's going to be a lot busier.We're going to be paying special attention to the minimisation of dust, vibration and noise.We want people to be able to work and think without our disrupting them.'

The team has been on site since December but, other than a couple of banners on the sides of the tower and some demolition work on a low-rise building behind the main tower, you wouldn't know it was there.

'Pretty much everything that isn't concrete is taken out during the soft strip, ' says Mr Dowling.'First of all, you take the ceiling tiles down and the aluminium runners that they are hanging from.You also take out the door casings, architraves and skirting boards - everything you can.The more you rip out now, the less you have to deal with once the building is down.'

This is because as much material from the building as possible is expected to be recycled, including the timber, which is processed into chipboard.The concrete is also recycled for use as aggregates. But this relies on good segregation of material.

Mr Dowling says: 'If you leave the wood in there, you only have to pull it out of the concrete debris before it is fed into the crusher. Better to pull out one 3-m piece of timber than try to separate it once its been broken into hundreds of 30-cm pieces.'

Once the soft strip has been completed and the asbestos teams have given the building a thorough clearout, the whole building will be scaffolded.Using a mobile crane, three 3-tonne mini diggers will then be lifted up to the top floor of the tower and will be used to bring it down floor by floor.

'They will be equipped with hydraulic breakers and shear attachments for cutting rebar.They will work from the roof down, crunching the concrete and then dozing it into the lift shafts.There will then be another machine in the basement that will be used to take the material away and sort it, ' says Mr Dowling.

Once the tower has been reduced to around 30 m from ground level, it can then be attacked by larger, ground-based plant. Long-reach excavators with pulveriser attachments will be used for the final stretch down to ground level.

The removal of a concrete ramp that joins the Maths Tower to the neighbouring Kilburn Building presents a more delicate task.As the ramp is attached to the Kilburn Building, the team will have to first construct a new scaffolding access ramp, then detach the old ramp by hand to avoid damaging the Kilburn Building.Only once the team has worked the ramp back around 3 m from the building will it be able to go in and pull down the rest mechanically.

As the nerve centre for much of the university's computing power, the Kilburn Building offers a second test to Connell Brothers.The ground surrounding the Maths Tower is dense with telephone and fibre optic cables, as well as gas mains and other services. Since a 90-tonne excavator is to be used as part of the project, it was vital that a full audit was carried out to relocate service ducts that could otherwise have been damaged, potentially knocking out computers across the campus.

But, having notched up around 10 major demolition projects in and around Manchester city centre, Mr Dowling is confident his team is more than capable to meet this and any other tests, bringing the tower down on schedule in August.

'Each time we do one of these jobs, we learn a little bit more.Our last job was the Eagle Star building. It had the Metrolink running past it, so that was a new thing to learn.Most of the lads on site are long-term employees, so they've worked on many projects and have learned these lessons.'

So with the knowledge the firm has built up and the possibility of a further £300 million to be spent on the campus development, this may not be the last time Connell Brothers' sums add up for the university.

Clearing the asbestos

ALTHOUGH the Maths Tower has less asbestos than many buildings of its era, Connell Brothers is taking no chances during its demolition. Before the firm set foot on site, a full asbestos survey was carried out, which pointed out all the likely risk areas.All workers have also been trained to spot further material that may have been missed during the survey.

On site, the main threat comes from Artex, which sometimes contains small amounts of white asbestos. It has also been found in bulkheads above windows in the tower and in fire doors.

The firm has its own specialist asbestos removal team, which is currently picking its way through the building, rooting out the problem.

Its first task was to make the whole building airtight, sealing any possible vents airborne asbestos fibres could escape through.Once the building was sealed, a single point of entry was established in the tower basement.Only trained asbestos operatives can go through this tent-like entrance that maintains a negative pressure, sucking back into the building to prevent any escape of material.All the workers wear full PPE, including chemical suits, masks and gloves. Each man also has a backpack that provides him with filtered air while he is working.

'Any asbestos found is sealed in a taped-up bag, ' explains Mick Dowling.'This bag is then placed in a second bag, which is also taped shut.'

These bags are then placed in a sealed skip that only the workers have keys to access, further reducing the risk of fibres escaping into the atmosphere.When the skip is full, it is taken away for specialised disposal by a registered hazardous waste firm.