Question
I just recently began a landscape project and have come across some issues
which I hope you can help me with.  Quick background, I live in Los Angeles
and my soil is a heavy clay and drainage is abysmal before amending.  I just
finished construction on a 6' 8" block wall with 18 in. L shaped footers with
the base of the L coming out in the direction of my yard, further complicating
drainage issues.  In one spot along the wall I have come across what seems to
be the rotting root remains of some ficus trees I had removed.  The soil there
is not draining at all and the dirt smells seriously rank.  I'm tempted to
remove the soil completely and just replace it with a topsoil, but before I
embark on anything so extreme and costly, I'd like to know if there is any way
to fix it.  Any suggestions?

Answer
Hi Sheri,  If the soil is 18" or so deep, don't worry about it.  The surface soil is the most important.  You had ficus growing there and they survived, no reason why other plants that like moist soil wouldn't.  At the surface to correct that type of soil, you should till in 50% or so organic matter and you'll need to lime the area.
Let the area sit a season and till it a couple of times.  Once the pH is correct, you should be able to plant the area.  I would not remove the soil, just repair it.  Jim