How much does a 6x6 timber retaining wall cost per foot?

July 1, 2010. I recently had a timber retaining wall installed. All work was done by hand. It took 4 men approx. 19 hrs to dig, build, and back fill a 4.5' X 19' wall made of 12' 6"X6" .4 pcf pressure treated timbers, cradles, tie backs, rebars, screws, cement, mortar, stone, sealer, and glue. The cost worked out to 35$ / sq. ft. These men worked very hard and build a very high quality wall. I wanted .6 pcf or higher timbers but it made the job unaffordable.