t-hangar and ice

In preparation for winter, I have a question.

the situation: T-hangar with bi-fold doors. Run-off from the roof
collects in front of the hangar door (because the tarmac doesn't
slope away from the hangar - in fact there is a slight dip in
front of the hangar). In the winter, water collects and then
freezes. Eventually the water penetrates under the door and
freezes inside the hangar. The result is a patch of ice about
4 to 6 feet wide, about half inside and half outside the door.
(imagine walking into a dark hangar and having black ice just
inside the door - weeeeee!!! splat!)

The best that Massport has come up with to date is to leave
the door slightly up so that the door won't freeze to the ground.
This does nothing with respect to being able to push/pull the
airplane in/out of the hangar.

Are there any suggestions on how to deal with ice in front
of the door?

--
Bob Noel
Seen on Kerry's campaign airplane: "the real deal"
oh yeah baby.