Digging a Trench

Digging a minor trench is easier and can be accomplished by using a simple shovel. However, digging deep trenches requires careful planning. OSHA defines trench as a narrow excavation made underground. A trench is deeper than it is wide but its width is not more than 15 feet. Trench excavation is frequently required for sewer installation and other such projects. Safe and successful trench digging requires careful planning.

Steps for excavating a trench

Planning is the crucial part. The route along which trench would be dug and the corresponding depth should be mapped properly to determine the tools and materials required. Process design should be meticulous to avoid wastage of time and resources.

Plan a route that poses least hazard to plants, property, sidewalks, structures and driveways. Factor in the soil type, as sandy soil, or wet and slushy material, can toughen up the digging process calling for additional support. You can tackle such soil types with shoring, wherein caving in of ditch sides is prevented by providing support structure such as plywood, steel trench box, etc. You can de-water the soil through well point system, mud-hog diaphragm pump, etc. to stabilize it. You can also bench the trench so as to take away excess weight from the banks.

Assess the depth of the trench to maximize support for the utility or other purpose for which it is to be used. The trench may be shallow on one end and deeper on the other.

Get in touch with local utility location service to spot underground pipes meant for electric, communications, gas or water transport and steer clear of any liability arising out of inadvertent damage of such utilities.

Now, you would need to arrange equipment to be used for digging. Minor excavations can be accomplished through pickaxes, shovels and hand tools; whereas large projects can be done with backhoes and mini excavators.

Check the topsoil layer’s depth and remove it up to a depth of 20 cm. Keep the topsoil away from other materials dug out to avoid mixing up and maintain the heap at 1.5m to prevent compaction.

Start digging with the first entrenchment reaching to the depth of first bench. Go on making subsequent entrenchments. Cast away the removed soil at a site far away from the excavation point to provide for encumbrance free work. Always move laterally along trench length. To avoid remedial jobs on the finished trench, keep checking the depth with builder’s level at grades which are critical. Keep checking trench depth as well as the stability of the embankments to carry out the needful smoothing or finished grading of the bottom to ensure effective installation of the material for which the trench was dug for. Following the installation, you will need to take effective measures to backfill the trench.

Quick Tips and warnings

• Always analyze the soil type to prevent bank collapsing incidents
• Call the local utilities call center to learn about utilities that are buried beneath the soil to avoid liabilities
• Never allow heavy equipment to operate along the banks
• Fence or flag off the trench to prevent accidental tripping of people
• Make way for safe entry and exit into the trench
• Do not dig trenches near existing buildings else you may run the risk of hollowing out their foundations.
• Obtain permit from local authorities prior to starting work near landmarks or public properties
• Never enter a trench not made completely on stable rock without adequate personal protective equipment
• Any protective system should be designed after considering soil type, cut depth, moisture content of soil, weather or climate induced changes, materials to be used and any other operation going on in the neighborhood.

Other important points to remember

Get the trench inspected regularly by a competent professional to properly map and comprehensively remove existing and predictable excavation related risks. Surcharge loads should be kept at a minimum of two feet from the edge of trench. Get the trench tested for oxygen level, toxic gases and other poisonous fumes.

You can employ a bed edger trencher to carry out clean shallow digging to allow for landscaping borders. A wire trencher can be used for installing landscape lighting and electric dog fences.

You can also get in touch with L&D Earthmoving in Australia which provides trench cutting solutions that are safe, efficient and proven for optimum results and zero liabilities.