I have a broken retaining wall that I'd like to fix up. It's cracked, presumably from water pressure building up behind it. It's rectangular, about 13'x33', and one of the four sides is connected to the house. The wall parallel to the house's back wall is the deepest. The house is on a hill, so I figure the primary purpose of this retaining wall is to provide a flat surface adjacent to the house.

The primary task is to fix the crack and to remove the underlying cause of the crack.

I never noticed any water coming through the weep holes, so I started digging up the back of the wall to see if there was any drainage system in place. It appears there were a few inches of gravel towards the base of the wall, but it has mixed in with the soil pretty well. The people who backfilled this wall all those years ago never separated the gravel with fabric.

• After I dig up the wall, should I dump gravel and fill it all the way to the top? Would that improve drainage? What kind of filter fabric should I use, and how should it be placed in the trench?

• Do I need to put some kind of pipe in the bottom of the trench (e.g a PVC pipe) or will the weep holes and gravel provide enough drainage?

The area enclosed by this retaining wall has always been quite muddy. Perhaps it has something to do with these downspouts leading to nowhere.

• Would it be a good idea to dig those up to find where all the downspout water is going to? It probably shouldn't be dumped into the ground inside the wall, right? If I had to reroute the water, where should I run it too?

After I fix all of the drainage issues, the next step is patching up the wall.

• Could I simply replace just this one little area without knocking down the entire wall? How would I go about knocking out a small area?