According to Todd H. :

The manual pump idea is a really good one. Do you have any examples
or where I might find some? It'd have to be one that I could get an 8
ft rise out of to get the water above grade and out of the house.
I'm picturing though that that may require a pedal powered contraption
heh.... Another Basement watchdog battery in parallel might be
better still. Hrmmm..

Lee Valley sells a manual pump (looks much like an old fashioned
lever-action well pump) that would probably work.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.