This article was taken from the February 2014 issue of Wired magazine. Be the first to read Wired's articles in print before they're posted online, and get your hands on loads of additional content by subscribing online.
Built during the Great Depression, the eastern span of the San Francisco-Oakland Bay Bridge was a marvel of utilitarian efficiency. (Some of the construction cranes were even incorporated as part of the structure.) But now that its graceful replacement is operational, the old span has to be taken down -- with-out dropping anything into the bay. Eric Smillie
Control the tension
The piers of the cantilever truss aren't holding the bridge up -- they're holding it down. "This is like a highly strung bow," says senior bridge engineer Brian Maroney. "You don't want to just cut the bow because the thing will fly off in all directions." So crews will first remove the pavement on the upper deck to lighten the bridge's load and reduce the tension. Next they'll isolate the steel supports, jacking them out of tension until they can be cut without whipping apart.
Cut the truss spans
Named for their length in feet, the 504 and 288 truss spans are not under as much tension as the cantilever, so there's less chance they'll explode in your face when you cut into them.
Build a monument
The massive art deco column of pier E1 may be preserved as a monument to the bridge that served the Bay Area for 77 years. The E2 pier may also remain and be an observation platform for the new span.
Blast the foundations
The foundations of piers E3 to E5 are like honey-comb. One idea: drill into them, plant controlled explosives around the internal walls, set off the charges, and let the concrete collapse into the void.
Mind the birds
The shallow-water foundations of piers E19 to E22 may be saved for a new pedestrian walkway and bird sanctuary. On the bridge, a long-armed snooper truck will be used to install spikes to deter nesting.
Nasa remodel The Nasa Vehicle Assembly Building at Kennedy Space Center, Florida, is big enough to house the Saturn V rocket that propelled men to the Moon. It even has its own weather system (mist often forms along the ceiling on humid days). Now it's getting an overhaul: the seven fixed platforms of its High Bay 3 must be detached, moved outside and demolished to make way for a modular system that can better accommodate a variety of different rockets and exploration programmes. Here's how contractors are completing one of the world's largest renovation projects. Bryan Gardiner
Old platforms out
The first step was to remove the seven steel platforms (weighing 140 to 230 tonnes) that once hugged shuttles and rockets.
Precise centres of gravity had to be calculated for each. After wiring and utility systems were disconnected, the platforms were lowered to the floor by a ceiling-mounted bridge crane. The crane is precise enough to touch its load on to an egg without cracking it.
New platforms in
The old fixed platforms will be replaced with a modular system of ten platforms that can be repositioned vertically and horizontally. That flexibility will be crucial for Nasa's new Space Launch System, which will rival the Saturn V rocket in size and is designed to offer a variety of configurations. The facility is also expected to host much smaller rockets from commercial space companies.
The end of the enterprise After more than 50 years' service -- including a cameo in Top Gun -- the 100,000-tonne USS Enterprise was deactivated in late 2012. It will be the first nuclear aircraft carrier of this class to be dismantled (in fact, the Enterprise is the only ship of its class ever built). The US Navy estimates that the project will take about 14 years to complete. Bryan Gardiner
Ordnance Off-load
To transfer some of the ship's munitions, Enterprise crew members fired shot lines over to the USNS Sacagawea and used them to string messenger lines made of wire rope. Then, while the ships travelled for hours through the Atlantic, just 30 metres apart, they slid ammunition packages across the water. Sounds crazy, but this sort of at-sea transfer has been used for supply replenishment since at least the late 1800s. The remaining ordnance was airlifted across in 946 helicopter trips.
Interior stripping
On December 1, 2012, the carrier pulled into Norfolk, Virginia, and its contents were stripped -- everything from tools to furniture, linen, technical manuals, spare parts and cryptographic equipment. The cranes removed weapon launchers, anchors, antennas and other large items.
DefuelLing
In June 2013, tugboats towed the ship across Hampton Roads harbour to Newport News Shipbuilding, where her keel had been laid in 1958. (Many of the workers taking her apart are the offspring of those who had built her.) Crews then removed the fuel from the eight reactors, but exactly how they do it is classified. The empty compartments, along with their radioactive piping, are even-tually sealed shut.
Spent-Fuel removal
The spent nuclear fuel is placed in containers with 35cm-thick stainless-steel walls (each cask weighs about 160,000kg). The containers are then loaded on to trains and trundled off to the Naval Reactors Facility at the Idaho National Laboratory for analysis and storage.
Towing
Onward! To the Puget Sound Naval Shipyard in Bremerton, Washington, via the scenic route. The Enterprise won't fit through the Panama Canal, so a tugboat will pull the hulk around Cape Horn and up the Pacific Coast. During the four-month trip, the two vessels will be anywhere from 400 to 700 metres apart, depending on the waves: ideally, when the tug goes up on a wave, the carrier should too. Constant adjustments to the length keep them in sync.
Scrapping and disposal
Each steel-encased reactor will be moved by barge from Puget Sound to the Hanford nuclear-storage site, where it will be buried in a radioactive package that also includes other nasties such as asbestos, cadmium, arsenic trioxide, cyanoacrylate adhesive and paints containing cyanide, coal-tar epoxy and chromium trioxide. And the steel hull? Chopped up and recycled, of course.
Data destruction Supercomputers typically become obsolete after about five years, and one of the latest to get its P45 is Roadrunner, which was officially shut down on March 31, 2013. Built by IBM and installed in 2008 at the Los Alamos National Laboratory, this $121 million (£75 million) daisy chain of 296 server racks and 122,400 processor cores helped model everything from the decay of the US nuclear-weapons arsenal to how white-dwarf stars explode into supernovas. The supercomputer cluster housed 34 disk drives, some of which almost certainly contained sensitive information. Los Alamos doesn't share the specifics of the removal and destruction process, but previously published guidelines from the US Department of Energy and the National Institute of Standards and Technology provide a sense of how it works. Bryan Gardiner
Overwrite, then apply magnets... or destroy completely
First, technicians overwrite data three times: twice with pseudorandom patterns and once with a known pattern. Then some disks are demagnetised, whereas others may be sent to a separate metal-destruction facility. Some places use a disk sander to abrade the recording surface. Others feed disks into a crusher, which pushes a steel piston through the centre of the drive. And others apply concentrated hydriodic-acid solution.
To raze the dam, move the river California's San Clemente Dam opened in 1921, and today its reservoir is choked with silt. That means an earthquake or flood could send a wall of mud sliming down the Carmel River and the valley below, damaging more than a thousand buildings. So dam owner California American Water and state and federal resource agencies decided to take it down. Dynamite isn't an option because of the dirt and water that would spew forth, so engineers devised a scheme to move the river instead. Eric Smillie
Cut a notch
Crews will cut a 135-metre-long canyon through the ridge behind the dam and carve a new river channel around the sediment. "I don't know another dam-removal project that's looked at that option," says Richard Svindland, director of engineering for California American Water. "River rerouting is tough." The largest dam removal in the state's history will involve building a diversion dyke to direct the water away.
Demolish the dam
To make way for the water, workers will haul 290,000m3 of sediment from San Clemente Creek (where the new river will run) and dump it on the main heap of silt, which will remain permanently. Eventually they will pick the dam apart with hoe rams.
Watch and wait
"Ideally, 20 years from now," Svindland says, "you won't know a dam was ever there."
This article was originally published by WIRED UK
