wikiHow to Excavate a Trench

For minor ditches or trenches, simply using a shovel and setting about digging is sufficient, but for excavating a deep trench, often needed for sanitary sewer installation or other projects, special consideration should be made. Follow these basic steps to digging a deep ditch successfully and safely.


  1. 1
    Plan your excavation. This step includes selecting the route and depth you will dig, and determining what tools, equipment, and materials you will need. Take your time in the planning and designing process so the layout will serve your purpose and you won't have to change your plan after you start digging. That way, the materials you purchase should be sufficient to complete the trench, and any utilities that need to be located will be addressed.
    • Choose a route that will not damage valuable plants or appurtenances on the property. Trees, shrubs and other plants may suffer injury or die if their roots are damaged in excavation. Driveways, sidewalks, and structures can collapse if they are undermined.
    • Determine the type of soil you will be digging in. Sandy soils, loose stony soils, and wet, mucky material will make excavating a straight, deep ditch difficult and dangerous, so you may have to plan additional measures to complete your project successfully.
      • Shoring. This process uses a support structure for your ditch sides so they do not cave in and injure anyone, or undo the digging you have done before the project is complete. Examples may be sheets of plywood with posts to support them for small excavations, or steel trench boxes or sheet piling for very large ones.
      • De-watering. This will remove the excess water from the soil to help stabilize it while working. This can be accomplished either with a well point system or a sock pipe and mud-hog type diaphragm pump to remove the water as it seeps into the excavation.
      • Benching the excavation. This is the technique for dealing with loose soils illustrated in this article. As the trench is excavated, the sides step down so the banks do not have to support more material than they are capable of.
    • This telephone cable, which is to be relocated, determined the starting location of the trench in the photos.
      Determine the depth the utility or other function of your trench will require. Some plumbing systems are gravity operated, and require a slope so the waste or water will flow unaided to the discharge location. In this situation, you may find the trench will be deeper on one end than the other.
  2. 2
    These flags are placed by the utility spotter, indicating a buried telephone cable.
    Call the local or government utility location service so that underground gas, electric, water, and communications pipes and cables can be spotted, to protect you from injury or liability in the event they are damaged.
  3. 3
    Get the equipment you will use to do the digging. Shovels, pickaxes, and other hand tools will suffice for minor excavations, but renting a miniexcavator can save a lot of work on large jobs. Backhoes and even trackhoes may be needed if the project requires a very deep and/or long trench.
  4. 4
    Remove any vegetation you will want to save and replace when the project is finished. Small plants, even turf grasses, can be removed and stored for replanting with proper care.
  5. 5
    Remove the topsoil to a depth of 10–20 centimeter (3.9–7.9 in), depending on depth of the topsoil layer. Store the topsoil away from other spoil material to avoid contamination. Ensure that the topsoil heap does not exceed 1 - 1.5m in height to avoid compaction. For the same reason the topsoil heap should either be demarcated or placed away from frequent foot or vehicular traffic. If the topsoil is going to be stored for prolonged periods of time over-seed with non-invasive grass species to reduce erosion.
  6. 6
    Begin the digging. Line your workers or equipment up with the ditch line, and start to dig. Be careful to observe soil conditions so that the trench embankments do not yield, allowing them to cave in.
  7. 7
    Dig your first cut to the depth you have decided is deep enough to serve the purpose of the trench, or if the trench needs to be benched, to the depth of the first bench. If using a piece of equipment such as a backhoe or excavator, dig the first trench segment the machine will reach to this depth. Make subsequent entrenchments to the depth of each bench prior to digging deeper, so the banks of each bench will remain stable throughout the process.
  8. 8
    Throw, or cast, the spoil (the removed soil) as far from the excavation as possible, so it will not encumber you while installing the utilities or doing whatever work in the trench it has been dug for. This will also prevent the removed material from creating an overburdening of the trench's banks (or sides).
  9. 9
    Move along the length of your trench as each section is excavated to the required depth. Checking the depth with a laser level or builder's level where the grade is critical will ensure the finished trench does not require remedial work to make it usable.
  10. 10
    Continue digging until the whole trench is complete. Recheck the depth of the trench, check the embankments for stability, and do any smoothing or finished grading of the trench bottom necessary to allow installing the material the trench has been dug for.
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    Install the material the trench is dug for. In the examples in the photos, the trench was dug to relocate an ATT telephone cable from an area where construction would ultimately render it useless. Your trench will likely serve another purpose, such as a drainage system for a cellar, or a sanitary sewer or storm sewer installation.
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    Backfill the trench. If you have access to one, a gasoline operated plate tamp will enable you to pack the soil as it is replaced in the trench. For deep trenches, backfilling in lifts (layers), and compacting the material as it is placed will reduce the amount of settling that will occur after the project is completed.
  13. 13
    Replace topsoil as soon as all the spoil has been back-filled. This will ensure fertile soil and easy re vegetation without having to resort to costly fertilizers.
  14. 14
    Regrade and relandscape the area after connecting any utilities you have installed.


  • 811 is a nation-wide toll free call that will connect you with a local call center that will notify most companies that bury pipes or wires. The companies then mark where their stuff is buried so you can avoid it. The call and the locating is free to the excavator. Some utilities only mark on public ROW and you need to allow at least 2 full business days for the locates to be done, but it is safer than digging blindly.
  • Keep hydrated, and in extreme heat or cold, protected from the weather during the work.
  • Have all materials needed to complete your project on hand before beginning.
  • Here, the different types of soils are visible in the trench side.
    Learn the characteristics of soils in your area to understand the risks of cave-ins or bank collapses during excavation.


  • Do not operate heavy equipment near the sides of a trench.
  • Protect the trench with fencing, flagging, or other means to prevent someone from accidentally falling into it.
  • Ensure that any trenches dug close to existing buildings do not undermine their foundations.
  • Provide a safe means for entering and exiting the trench. This may mean using a ladder or sloping bank for this purpose.
  • Do not allow anyone into a trench that could cave in or collapse.
  • If you are trenching near within close proximity of a railroad or historic landmark, Environmental Information Regulations must be submitted with permit.
  • Here, rebar and caution tape warn people of the open trench.
    Do not do any excavating without having underground utilities located prior to beginning.

Things You'll Need

  • Tools or equipment for digging.
  • Tools for laying out the trench, such as measuring tape, hammer, wooden stakes, or flags.
  • A builder's level or laser level for determining the elevation of the trench.

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