If it's a light duty, 120v pump only drawing a few amps, I'd use direct
burial wire, #10 (due to the length) and tie it through an outdoor switch
or timer to a GFI protected outlet.

Eisboch


Ahh...direct burial wire...that's what she can use to tie up my casket
after I dig the ditch! 18" sure ought to work here, since our freeze is a
lot less than your freeze. I have an exterior GFI outlet...is it safe to
assume an electrician can wire an outdoor timer to it? As you might guess,
I don't "do" electricity.



Either direct burial or wire in conduit will work here in Missouri, but must
be 36" deep. This is a safety thing, since our freeze level rarely
approaches 12".

CATV= 18" min (6" house drop)
Phone & Gas = 24" min (12" house drop phone, 24" gas)
Water= 36" min (always 36")
Power= 36" min (always 36", risers in conduit)

I would follow code. There's always a possibility that a shallow A/C wire
could come back to bite you if someone else digs into it.