A few weeks ago there were two serious industrial accidents –  the BP Deepwater Horizon oil spill in the Gulf of Mexico on 4/20/2010 and the MWRA water main break in Boston on 5/1/2010:

Broken 21″ oil pipe 5000′ down in the Gulf of Mexico

Broken 120″ water pipe in Weston MA

At first sight, the Boston break was more serious.  It was actually a 1000X larger break – it dumped 300 million gallons of water a day into the Charles River (which doubled its flow!) compared to the 300 thousand gallons of oil a day from the BP spill.  It directly affected the water supply for two million people.   In a matter of hours the word went out to the entire area – the tapwater was not safe to drink and had to be boiled or chlorinated.  How many people would be sickened by contaminated supplies?  There was still water supplies for toilets and fire hydrants, but how long would it last?

The BP spill initially looked like a problem for just BP.   Spills like this happen every several years.   The pictures of the burning oil rig were surreal and apocalyptic – many noted how they looked like something from an SF movie.  11 people were reported dead, but (sad to say) that statistic doesn’t have much impact in the context of big accidents.  Everyone expected that BP would shut off the flow and then pay out a couple billion in damages, and that would be that.

Yet the Boston break was fixed in just two days, and the boil-water order was lifted in four.  No one was sickened and no one died.  People were irked at having to dash out and get bottled water (although boiling was cheaper and more convenient), but many were actually energized by the emergency, the way they are when a good blizzard comes in.

The BP spill is still not capped after six weeks of desperate effort.  There are now tens of millions of gallons of poisonous glop floating around in the Gulf, killing the wildlife, ruining the fishing, and destroying the shoreline.  BP is looking at hundreds of billions in damages, and probably bankruptcy.   Americans are once again looking like helpless incompetents, as they did after Katrina.  There isn’t going to be a clean beach left in the northern Gulf.  Whole species of marine life could be exterminated.

So what’s the difference between the two accidents?  In a word, backup.   The Boston water main had a giant valve just upstream from it that could shut off the break:

Now that’s a faucet

That let them clear the water from around the break so that guys could get in to fix it.  That was heroic work – two welders were in the pit around the pipe for 18 hours to attach a new collar around the break.  It turns out that the company that built the pipe, Barletta Construction, happened to have a spare collar in their yard – more backup.  It turns out that the Massachusetts Water Resource Authority (MWRA) actually gamed out a situation like this in 2006 and knew how to bring new water supplies on-line from local lakes – still more backup.  They’ve even been fixing up an old pipe, the Hultman Aqueduct, for use as a redundant supply.  It’s not due to open for another four years, but after that even this minimal disruption can be avoided.  Their full report is  here.

BP did have backup on their well – a so-called blowout preventer:

A large, complex set of valves for controlling the pressure in an oil well

There’s a good discussion of how this works here.  In summary, a driller has to be careful when digging into an oil or gas reservoir to maintain the pressure on the well itself or else the 1000s of PSI pressure difference between the well and the surrounding rock will make the fluid shoot out like, well, a gusher.  The blowout preventer allows them to regulate the pressure by controlling the flow of mud and oil/gas in and out of the well.

But it didn’t work.  It’s in pieces on the bottom of the Gulf along with the riser pipe and the rig itself.  It’s not clear why it failed, but it doesn’t seem to have been well-maintained.  Without it, there’s no control at all of the flow.  BP has to work around an active pipe under a mile of water with wreckage everywhere.

I can’t comment on whether they’ve done all they can on the capping or the containment of the spill, but it sure looks like they have every incentive to do so.   They’re faced with a catastrophe.   If they’d had more backup on the sea floor, on the riser pipe, and on the rig itself, they might be in the MWRA’s position, of having a bad problem that was quickly solved, instead of having a disaster that’s almost impossible to solve.