I think if you alternate floor tiles, you can make all the pumps at once without waiting for each one to be built.
The standard, compact pump stack works by stacking pumps on the same two squares on all z-levels, leaving open spaces below pumps, for power transmission from the pump below. This makes the pump "hanging," like a waterwheel or a vertical axle. It's not legal to start a hanging machinery item unless there's something at least planned below, and if it completes before the supporting item, it immediately deconstructs. I've had this happen with conventional pump stacks, placed 10 at a time and had half of them fall apart because they were completed in the wrong order.
This happens even if only one of the two tiles below the pump is an open space (which is the way I always did it).
My alternate stack looked like this:
level z
##.###
#0>>.#
##*#.#
######
level z+1
####.#
#.#*.#
#.<<0#
######
>, < = pump direction
* = gear over open space to pump below
O = open space to level below
The gears must be built after the pump below is complete, but that's the only dependency, the pumps can be built in any order. The drawbacks are it requires an extra gear for each level, and takes a 4 x 4 block for the pumps instead of a 4 x 2 block. The time required to make the mechanisms and place them wasn't too large, but the extra 5 power is kind of significant.
- Gus