ACQ treated hardwood with cup bolted uprights 800 mm ACQ hardwood timber retaining wall with M10 Cup bolts Retaining wall Posts at 2.4m centres 200 x 100 Hardwood posts on a 10 degree pitch with 2.4 m hardwood sleepers for this 1 meter high retaining wall. 200 x 100 Hardwood post on a 10 degree pitch with 2.4 m hardwood sleepers for this 1 meter high retaining wall with 2.4 meter return. hardwood timber retaining wall