Foundation Engineering Corporation (FENCON) of Montreal was selected as the design and construction engineering company for the Diefenbunker. FENCON was later subsumed by what we know today as AECON Group.
FENCON had what might be called an interesting challenge.
“Design a structure that can hold up to, oh let’s say 500 people, for about, I don’t know, maybe 30 days, after some bomb-thingies strike the Ottawa area, and which will survive all that blast, radiation and nasty fallout stuff.”
Well, that was fun to write, but it’s a very unfair depiction of the task given to FENCON. Scrutiny of material (almost all of which is now unclassified) in Library and Archives Canada, DND’s Directorate of Heritage and History, and the Diefenbunker Archives themselves show the deliberations of senior government officials to define the threat and the requirement, in the very real context of the Cold War and the chilling phrase Mutual Assured Destruction, appropriately known as MAD.
The project was discussed under limited code-word security. Project/Operation BRIDGE, RUSTIC and EASE (Experimental Army Signals Establishment) were used at various times to refer to what would become the Diefenbunker.
The FENCON engineers had to make many assumptions – the magnitude and nature (air or ground burst) of nuclear weapons likely to strike Ottawa, where they might strike based on strategic assessments and best-guesses of the likely error in delivery systems’ accuracy, the immediate effects of blast, radiation and fallout, and the probable enduring impacts on, for example, air and water purity. Weapons effects information was gleaned from information shared by the USA from their many tests in the Nevada desert.
It’s evident from archive material that the assumptions which underlaid the design were developed by a wide and well-informed group, and that the assumptions were comprehensive, detailed, and disturbingly graphic.
This led to the basic concept of the structure – an underground facility afforded a much cheaper and more easily constructed design than one on the surface – and to a host of design aspects intended to minimize the effects of blast and to shut down all linkages to the outside world – air, water, power, communications, etc – in milliseconds on detection of a blast.
Ultimately the design was for a 100,000 sq.ft. building equally distributed over 4 floors, giving a square footprint of about 160 ft on a side.
One interesting design element and perhaps the best known aspect of the Diefenbunker is the approach blast tunnel. If you’ve seen the excellent movie Sum of All Fears, based on a Tom Clancy novel, the opening sequences as the President and his senior advisors rush down a long tunnel and into a meeting room were filmed in the Diefenbunker.
The approach Blast Tunnel was designed to a specified strength, size and overhead protection, and configured so that a blast would effectively pass through the tunnel and out the opposite end, passing at right angles to the main Bunker entrance, which was nevertheless protected by massive hydraulically operated armoured doors.
The Diefenbunker holds much of the FENCON design proposal documentation, which lays out in admirably brief and stark language the assumed effects of strike, the required immediate reactive and protective physical measures, and the longer term facilities and services required to survive the effects and provide critical Government of Canada services from within a locked-down building.
The FENCON design proposal addressed every aspect of immediate response to an attack, and the support facilities for an extended stay underground – power, fuel, water, food, communications to the outside world, waste systems, and measures to mitigate likely mental and emotional reactions among the sealed-in occupants.
Getting construction underway and moving quickly demanded even more ingenuity from the engineering team (now including FENCON and Army engineers) as design adaptations were introduced concurrently with construction, all under intense time pressures, and within a construction site and building frame extremely constricted in building and working space.
How was this managed? – by the first use in Canada of the Critical Path Management method for a large construction project.