On 15 Jul 2008 13:19:58 -0400, (David Combs) wrote:

Our driveway is sunk maybe 5 feet down from the
level of the front yard, and they're separated by
a rock retaining wall. ...

So they're holes between some of the rocks, of
size, at the largest, maybe six inches in both
directions.

Question: what to do about it? ...

Oh, whatever you use to fill up the holes,
do you have to make a big deal of mixing it,
or might it come "ready to use"? Pros and cons?

Just something to keep in mind: Not that I've ever built one, but I see
a lot of tipped over retaining walls. I think is due to water pressure.
IMO, you need good drainage from the back side. One way to do this is
to leave the joints fairly open.

G