This week the teams have to construct a water tower capable of holding 1,000 litres of water in a single tank 6 metres above the ground. The base of the tower must be no more than 3.5 metres wide, and a pipe has to run from the top to the bottom so the tank can be drained and the pressure tested.
The first consideration has to be how to construct a tank that's capable of keeping a tonne of water off the ground. After that it's a matter of making it strong enough to withstand attempts to destroy it. A top-heavy structure like this is easy to knock over, so the teams have their work cut out.
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The Highway Men
Dave May: Engineer
A qualified civil engineer, Dave works for the Highways Agency as a design manager. With experience of working on roads and bridges, he's confident that his team can build any structure.
Tom Kenyon: Builder
Tom is more used to building pedestrian crossings and adding extra lanes to motorways than constructing water towers but he does have a talent for invention. Here's hoping that that includes water towers. Outside work, he unwinds by kickboxing or spinning discs on the decks.
Phil Hardy Bishop: Demolition
Warehouses and grandstands have fallen by Phil's hand. He believes that you need to know how a structure is built in order to be able to destroy it properly, so he'll be fine as long as the other team's design doesn't have any hidden surprises. |
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Explosive Mix
Alan Wright: Design Engineer
Award-winning designer Alan has over 16 years' experience in the trade. He's an expert in conservation design and has worked on special projects as a consultant for both English Heritage and the National Trust. Outside work, cricket and rock music float his boat.
Robert Myers: Builder
With over 30 years' experience as a builder, Robert has worked all over Wales and the south west. He's even done a stint in Hanover, Germany, Auf Wiedersehen Pet style. His day job currently involves building house extensions in the Cardiff area.
Gary Tuson: Demolition
Manchester United fan Gary has over 25 years' experience during which time he has demolished everything from factories and flats to military bases, multi-storey car parks and bridges. Water towers watch out!
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Water towers are basically special supplies or emergency reservoirs of water. They are constructed so that towns and villages can still receive water even if there is a pump failure on the mains system. Because the water is stored high up, they can use gravity to transfer it to the consumers and don't have to use pumps. As a top-heavy structure, a water tower has to be both strong and stable. Unfortunately our teams have only a limited amount of concrete so they'll have to rely on plastic pipes, sandbags, plywood and oil drums to make the best of it.
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The Highway Men's water tower
The Highway Men get to work on a basic design built around a telegraph pole. Plastic pipes set into oil drums act as support pillars and the whole lot holds a plywood tank 6.5 metres off the ground. To protect their tower against demolition, the team surround it with straw bales and extra plywood to hide the core of the design.
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Explosive Mix's water tower
Explosive Mix design their structure so that it has a low centre of gravity. This should make it more stable and enable it to withstand the assault of the demolition tools. A central column supports their water tank 6 metres above the ground. Around the column, a series of platforms are built on top of oil drums, like a wedding cake. A concrete foundation base with built-in threaded steel bars helps clamp the structure to the ground.
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Judge Steven Swan from Anglian Water knows a thing or two about water towers. He'll be looking for a design that's watertight and strong. This week the test is in two stages. Firstly, the tank is filled with 1,000 litres of water. Can the structures cope with the weight and not lose a drop? Then there's the pressure test which uses the Demolition Day tea urn! Can the towers provide enough pressure to fill the urn in one minute?
First up it's The Highway Men. They watch nervously as a water bowser is lifted up to the top of their tower and then opened to fill the tank. The telegraph pole and pipes stand up well, and soon they achieve the 1,000-litre mark with no leaks or structural failure. Next, the pressure test. No problems there either: the tea urn fills to overflowing in no time.
Explosive Mix prepare for judgement. Their tank fills with only a small leak which Steven Swan fails to notice. The pressure test goes like a dream with another filled urn. There'll be plenty of tea tomorrow on Demolition Day.
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Both teams have passed the test but Judge Steve picks The Highway Men as the winners of this stage because their design worked best as a water tower and filled the tea urn fastest. That means they get first choice of the tools of destruction. The first team to smash and mangle the opposition's structure to less than one metre above the ground is the winner.
After checking out the job to be done, Highway Man Phil chooses the monster wrecking ball. Explosive Mix's Gary goes for an equally menacing piece of kit: the MH21 grapple.
At the sound of the claxon the machines launch into action. With two colossal impacts from the wrecking ball, Explosive Mix's tower topples to the ground. To combat this, Gary gets the grapple to rip the tank from the top of The Highway Men's structure. Meanwhile the wrecking ball is trying to flatten the wreckage of Explosive Mix's water tower. Unfortunately for The Highway Men this isn't the best tool for the job and disaster strikes as the machine's return cable breaks. While they struggle on, Gary is methodically guiding the grapple to rip the opposition's tower to pieces, bit by bit. The technique pays off and as the claxon sounds Explosive Mix steal the show.
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