Size the trench so there's enough room for the retaining wall block and at least 8 in. of space behind it. Excavate deep enough to completely bury at least one full course, including space for 6 to 8 ...

This is the last of three stories on terracing hillsides. To read the first two stories, "Slippery slopes" and "Know your hillside," go to sfgate.com and type in Deborah K. Rich. "Almost all ...