How to Shore a Trench

Rachel Lucio

Trenches must be dug to lay any variety of cable or pipe underground. Most home projects will not require a trench so deep that shoring is needed, but if the trenching project is particularly large, shoring the trench may be required in order to prevent the collapse of the side walls. The Occupational Safety and Health Administration requires any trench 5 feet or deeper to be shored.

Deep trenches require shoring.

Step 1

Consult an engineer and create construction plans. If it has been determined that a trench needs to be shored, consulting with an engineer should be the first step in preparing construction plans. An engineer can help with project logistics.

Step 2

Obtain city and county permits. Call or visit city and county offices to apply for and obtain permits before beginning excavation to avoid unnecessary delays or work stoppage.

Step 3

Train for the project. OSHA requires the presence of a "competent person" onsite at all times to make critical safety decisions. OSHA defines a competent person as someone who has experience in excavation, who can identify hazards and unsanitary working conditions, and who has the authorization and know-how to correct hazardous situations at the jobsite. Experience in structural design is also required because the competent person may be required to design safety ramps for the secure movement of people and equipment. Check with OSHA or local commercial construction supply companies for information on local OSHA competent person certification classes.

Step 4

Mark utilities. Gas, water, sewer, electric and cable lines can all be found underground. Contact local utility and cable companies to come out and mark the jobsite. Marking the site will allow for safe digging, and also indicate any adjustments that may need to be made to the original trench plan to avoid potential hazards.

Step 5

Rent equipment needed for digging and shoring. Heavy equipment is needed for both digging the trench and setting the shoring. Equipment may include a backhoe, trench boxes or shields, hydraulic shoring system and lighting. More equipment may be required depending on the state of the jobsite and any safety hazards that may be present.

Step 6

Excavate. Dig the trench in accordance with the excavation plan. Excavated soil must be placed a minimum of 2 feet from the top of the trench wall to prevent collapse.

Set shoring boxes or shoring system according to manufacturer’s instructions.