"Frank J Warner" wrote
Finishing up my house. Back yard is last thing I have to do. It's got a
hillside that slopes down maybe 20 degrees to the back my house. I need
to put retaining walls to keep this hillside from ending up in my
bedroom during next year's heavy rain.

This evening, while taking my walk, I followed a dry creekbed that had
been shored up in places with heavy guage galvanized corrugated sheet
metal. Looks very much like this stuff:

If the sheet piling is too rich for your blood, you might try mezzanine
decking pans. They're narrow enough to drive without a large machine, and
pretty stout. You can find "drops" all over multi-story concrete
construction.

LLoyd