Bradco model 625 skid loader mounted trencher may be the best option for the big jobs. It trenches to 48" as opposed to 36" max for our walk behind trencher. The "crumber" option on the digging boom acts as a clean out tool by collecting and dragging loose soil that then is ejected from the trench by the digging chain. Cuts a 6" wide ditch. Trenchers are sometimes referred to as a Ditch Witch or DitchWitch or ditch digger or trench digger.