7878,
You said----"Tan Driveway?"
Was this driveway premixed during the pouring process or was it post-painted or stained the Khaki color???
Colored driveways are done here but not of those exotic colors unless it is acid etched.
I would hope that the power washer wouldn't peel the paint off or worse...
Don't use Bleach or Acids......it will possibly fade the color.
Man, I hate that for you.......as our mulches do leach some color after rains, but we have never stained concrete. If the mulches are wet from rain, we definately don't park on the smooth driveways until the mulch is dried..
We hate to wheel barrow bulk mulch from the street side, but in this instance we would do it or wait until better conditions. Depends on several factors!
Contact a concrete company and inquire with them on the techniques for cleaning the surface.
Good Luck!!!!!!