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Heavy session

The first new whisky distillery to be built in Scotland for 30 years will open in the Spring, to supply 10M litres per year to the world.

On Burns Night it is customary to eat haggis and quote the poetry of Scotland’s Bard, washed down with a dram of whisky. But this pleasure is not confined to Scotland. Whisky is an internationally renowned luxury, and demand for it is ever-increasing.

Growing demand has encouraged drinks company Diageo to build the first new whisky distillery in Scotland for a generation, which is under construction at a site near Elgin, Speyside.

Diageo’s project director for the new distillery Mike Jappy explains: "What we are seeing is demand for whisky increasing over the last few years, particularly in fast-growing economies like Brazil, Russia and China. "We have an exciting product and we have to look at how we are going to make a step-change to meet this demand."

The whisky made at this new distillery will go into blends such as Buchanan’s, Johnny Walker, Bells and J&B, mostly for export. This distillery will eventually produce significant quantities of spirit: "The capacity will be 10M.l of spirit per year. To put in perspective, the average malt has about 3M.l capacity, with the current largest at 6M.l," Jappy says.

Diageo talked to consultant Faber Maunsell Aecom in 2006, which won the design contract in March 2007. The total cost of the project is £40M and the construction cost is £12M. Construction of the main distillery building is nearing completion. It is 150m high and ranges from 40m to 50m wide.

At one end, the distillery floor has to carry an unusually heavy load – 14 fermentation tanks weighing 150t each. The floor also has to bear the weight of 14 copper stills weighing 30t, two 120t mash tuns and 20 condensers weighing 7t. Faber Maunsell Aecom senior engineer Nathaniel Buckingham explains: "In this building everything has a considerable weight. "The tanks each have bespoke struts to support them. With most of the weight at one end [where the fermentation vats are] the ground needed stabilising.

"We carried out a zone test with vibro-stone columns. Normally we would conduct a scale test but we pushed the boundaries for this process –2,250kN of pressure was used to simulate the load. "We expected up to 12mm settlement, but found just 6.5mm. We used 1,500, 600mm diameter vibro-stone columns to give a bearing pressure of up to 250kPa at the heavy end," he said.

"The foundations are traditional, but at the heavy side is a 500mm raft foundation, to limit settlement,” he says. The building’s structure is designed to allow easy maintenance of the process tanks and stills. “The ceiling has structural redundancy, in case the fermentation units need to be replaced, so the roof or walls can be removed. Similarly, replacing a still is a relatively common job, so we needed the design to allow us to also remove a still without removing the roof," says Jappy.

The superstructure is formed from 900t of steelwork, galvanised because of the location and exposure to give a longer design life. The walls and ceilings are braced frames, leaving the structure largely open-plan and creating a very large space. The aim is to produce a
building with minimum environmental impact. "Our aspiration is for an excellent rated BREEAM [Building Research Establishment Environmental Assessment Method] structure," says Jappy.

To achieve this, the building and the process it houses had to become integrated, reusing the heat and water generated from the distilling process. "Local firms did the steelwork, increasing the building’s BREEAM score. We are quite remote, but a lot of the subcontractors are locally based, for example the galvanising was done by a firm in Elgin and this also helped with the [BREEAM] scores," said Jappy.

The building’s green rating is also helped by the fact that it is next door to an existing malting plant, which will supply the distillery with malted barley. "Barley is dried, stored and processed, and then taken to the distilleries. "When the distillery is complete, the entire barley output will be taken next door for distillation," says Jappy. But the main way the distillery’s environmental credentials have been enhanced has been its ability to reuse waste from the distilling process. In the past, the residues would be removed and used as animal feed. "Now, the spent grain and wash [water/barley residue from the distilling process] is re-processed to generate steam to go back into the distillation process. Although 9t of ash is produced per week," he says.

Spent wash is high in carbohydrates, and is processed in an anaerobic digester to create methane, which goes to the burner. Clean water is regenerated for use in the existing maltings plant. "The environmental aims were to reduce the fossil fuel and water used," says Buckingham. "Now, no additional water is used." According to Jappy: "The aspiration is to offset all the distillery’s energy, but we have got to about 65%. Incremental improvements will improve on this, and it is possible, in time, to achieve this."

The new distillery is due to come on stream in the Spring.

DISTILLED WISDOM: MAKING GREENER WHISKY

1) Barley from neighbouring malting plant is "malted" – made wet and then left to germinate. This activates enzymes which turn its starch content to sugar. After six to seven days, the malted barley is dried.

2) The malted barley is ground and mixed with water to make mash. The mash is filtered and the liquid or wort retained. Waste fuels a biomass boiler which produces steam for the distillers.

3) The wort is cooled, yeast added and fermentation begins, creating a liquid which smells something like beer.

4) In copper stills, the liquid is steam heated and distilled twice. During this process, water and alcohol are condensed and collected. Waste heat is transferred to the malting plant.

5) This liquid is then diluted to around 63% alcohol and is then put into oak casks for maturing.

6) Once mature, the whisky is diluted with water to between 40% and 44% strength before it is bottled and sold.

WHO’S WHO

Client: Diageo

Lead consultant: Faber Maunsell Aecom

Architect: Austin Smith Lord

Principal contractor: ROK Construction

Ground engineer: Keller Ground Engineering

Foundations/concrete: Andrew Cowie Construction

Drainage: GA Duncan

Steelwork: RIM Fabrication

Cladding: E-Clad

Curtain walling/windows: Marshall Brown and Charles Henshaw

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