8141 Timber crib retaining walls (0) 8142 Timber post retaining walls (0) Site retaining walls constructed with treated timber posts, installed at intervals with timber lagging between uprights to retain the material to be supported 8143 Timber pole retaining walls (0) Site retaining walls constructed with treated timber pole piles , installed to provide a continuous wall surface or installed at intervals with timber lagging between uprights to retain the material to be supported 8144 Timber log and sleeper retaining walls (0) Site retaining walls constructed with large format timber logs and sleepers, usually laid horizontally to provide a vertical or staggered back continuous wall surface to retain the material to be supported. Includes dead-men, stakes and other anchor methods.