the best pit design I have seen is a concrete rectangular (3' x 5' ish) pit with a recessed (1" or so) plate steel cover. then 3 short pipe sections are welded to 3 centered holes where water drains into pit. this keeps sand on top (mostly). 2 handles on cover, one on each end are used to lift cover off to muck pit). inside pit, 4" pipe to drain pit (off top) is coupled to a 't' facing up and down (keeps debris out).
if you are in a cold climate, use
doors. best idea for
door operators is to couple the shaft to extend it and mate with operator inside your dry equip. room. this will greatly extend the life of the operator and at $800-1000 each for NEMA 4 operators, it's worth the extra work when building.
heat entry and exit pads and pitch concrete to keep water in bay as much as possible.
make man
door threshholds in pump room slightly elevated so if you flood it doesn't ice the man
doors shut.