Drum roll

So why is CIOB member Jeremy Dale, Bovis Lend Lease's project manger for the £21m Wildscreen World in Bristol, grinning from ear-to-ear as he conducts a tour around the works? After all, the project is one of Michael Hopkins & Partners' most complex designs. It features a four-storey brick drum which contains a 350-seat Imax cinema, an ETFE-roofed botanical garden and the entrance is a tensioned-fabric structure. It even contains a listed leadworks that has been converted into a cafe. All this had to be built for £13m (not including the £8m for fit-out) on a strict timetable dictated by the availability of Imax screen painting equipment.

Dale explains that the four-storey high Imax screens require painting with a special aluminium paint. And, he adds, there are only three rigs in the world capable of completing each six-week screen-painting project. So, it is vital that when the Imax rig is booked in, the project does not over-run. "If you miss your slot, who knows when a rig might become available again," says Dale.

The reason Dale is grinning is that the Imax cinema opened on schedule. On 20 April, Bristolians streamed into the cinema to watch Blue Planet – a survey of the Earth taken by Imax cameras on a space shuttle. The rest of Wildscreen World is not likely to open until July, but for now Dale is delighted that despite two major construction obstacles, the Imax opened on time.

Dale's first major problem was with the piling. Wildscreen World is built in Bristol's historic dockyard. Because of this, engineer Buro Happold and Dale were expecting trouble. Buro Happold's engineers dug a 7m wide, 3m deep test trench across the site. But no obstructions were discovered.

Piling began on time, but after just a few days the piling subcontractor hit obstructions. A second survey was done which revealed a 17th-century dry dock, with thick walls and a solid oak bottom. There was no way through.

Dale and Buro Happold had a rethink. Instead of using continuous flight auger piles, which were being used to keep site noise down, mini-piles had to be used. This meant using twice as many piles as originally calculated and incurring a potentially crippling delay.

Dale's change to mini-piles also risked annoying the neighbours of this city centre site. Dale made great efforts at the beginning of the project to keep the local hotel and school informed of potential noise nuisances. He even requested an exam timetable from the school so that he could schedule noisy works away from exam times.

Fortunately for the sake of the programme, the dry dock was nowhere near the Imax theatre part of the site. So with a bit of resequencing, the piling of the Imax theatre continued unchanged, while the rest of the site had to play catch-up.

But just as Dale looked to have saved the programme, disaster struck. He had a phone call from Bristol City Council informing him that there was a danger of unexploded World War II bombs on the site. Work stopped for two weeks while the army swept the site. Nothing was discovered but Dale was set back by two weeks. "The delays ate up all the float and we had to start coming in on Saturdays and Sundays," he says.

Dale's other great challenge was building the Imax theatre drum. The 23m high, 30m diameter building has windowless walls containing 550 000 loadbearing bricks joined using lime mortar. This meant the 40 brickworkers working on the project had to be incredibly accurate because there are no expansion joints to take up any slack.

But just two weeks before the brickwork was due to start, the brick supplier that had been specified by Hopkins informed Dale that it could not fulfil the order. "We started a desperate search for 38 Newton bricks that did not contract or expand too much and were the right red colour to match the local dockside warehouses," says Symonds project manager Iain Gilmour.

He adds: "In the end there were only about four bricks to choose from and they needed a 16-week lead-in period." Dale cuts in: "Hopkins plumped for Furness brick but this was too expensive. So we chose Optiroc bricks from Holland which were then sent to Manchester for cutting [the bricks needed cutting and numbering to form the loadbearing lintels]."

The project team then compressed the lead time to 11 weeks. Dale explains that this was done by bringing an architect into the office full-time, so that instead of two-week approvals, brick approvals could be turned around on the same day. Eventually the brickworkers started in July 1998 (three months late) and finished in March 1999. Working through the worst of weathers, the brickworkers earned the respect of @Bristol chief executive Gillian Thomas by taking their tea breaks up on the scaffold, cowering under a tarpaulin. She was so impressed by their spirit, she bought them a tin of biscuits, which, according to Dale, were greatly appreciated.

The three-month backlog caused by the specification of new bricks was absorbed into the programme by overlapping the fit-out with the shell-and-core programme, explains Dale. Gilmour adds: "It was naïve of us to think we could finish the shell-and-core and then hand over to the Imax contractors." While dovetailing the shell-and-core and fit-out works sounds simple, it was a tricky task, says Dale. "Our package manager, 22-year-old graduate Rob Devall was a star. There were no hitches even though the Canadian Imax team were working in Imperial measures," he adds.

The site problems have squeezed the budget. And Hopkins has had to sacrifice on some of the finishes, explains Gilmour. He says that Hopkins originally wanted glass blocks in the floors of the Imax theatre walkways, as well as in the floor below. These have had to be sacrificed, says Gilmour.

The project team also saved money by persuading the architect to change from full height glass doors to standard sizes with head and side panels. They also replaced the glazed roofing that covers the link between the Imax theatre and the rest of Wildscreen World with ETFE. This meant less structural steelwork.

Dale adds that a lot of cost was also taken out of the ramp that weaves through the botanical garden. "Originally this was a blockwork ramp with a concrete finish. Then we found out how much fill was being brought in. So we decided to use 700 tonnes of fill to create the ramp and then just put a timber and steel facing on top," he says.

Dale has moved on to his next project – the new £160m Vodafone headquarters – where he is deputy project manager. So he only returns to Bristol occasionally. But each time he does, the grin starts spreading.