Re: manhole covers

[Sean Donelan <sean () donelan com>]

Check out Georgetown in Washington DC, the exploding manhole capital of
the world.  They have a lot of experience with exploding manholes, from
many different causes.  The most recent incident was in the last couple of
days.  There is a lot of energy in being pumped into utility lines.  A
short circuit can release that energy into the underground vaults, and
blow the manhole cover a considerable distance.

http://www.washingtonpost.com/wp-dyn/articles/A33073-2003Feb19.html

The Washington Post also has a special report covering exploding manholes

http://www.washingtonpost.com/wp-dyn/metro/specials/manholes/



On Thu, 20 Feb 2003, Allen Hamner wrote:

> I am a chemist who consults with the mayor of Bluefield WV where an
> incident two weeks ago (a cold day) blew a 70 pound iron cover 10 feet
> from an conduit tunnel containing several public untility lines.  We
> believe we can exclude a natural gas leak.  Rumor has it that hydrogen
> is involved, which may arise by electrolysis (?) or pyrolysis of
> insulation (?).  A previous incident had done no damage but this
> explosion destroyed a nearby plate-glass window.
>
> There is no coal in the area so mine gas seepage is excluded.  Sewer
> gas is tentatively not an issue.  The source of the spark is unknown.
>
> I would like to participate in the exchange on this topic.
>
> Allen Hamner (Ph.D.)
> hamner_a () wvwc edu