Is there a general rule for sizing and locating weep holes in an EXISTING
(stuccoed) concrete block retaining wall?  (Not sure if the block is hollow
or solid, but I suspect the block is hollow, or webbed.)

The two retaining walls to which I am referring are 52 inches at their
highest point (and gradually step down to a height of about 24 inches) over
a length of 22 feet (wall 1) and 18 feet (wall 2).  They were never
outfitted with weep holes, so I am "retrofitting" them before restoring the
existing walls.  I was poised to drill out 4-inch diameter holes at some
arbitrary location in the walls, but thought I might check with anyone who
might be knowledgeable in this area first.

Thanks in advance for any help you might provide.

Donna R. Cubberly