Being a Good Neighbor During Construction

Cut-and-cover or trenching

Adding new pipeline or repairing existing pipeline is sometimes accomplished using cut-and-cover, or trenching, construction techniques. To minimize local disruption, trenching work is generally done in segments, with each segment taking several days or weeks to complete. When one segment is done, the construction operation moves to the next segment. A trenching project might consist of several segments.

Most trenching operations take place in public streets or rights-of-way. First, equipment is used to break up concrete and asphalt. Then trenches are dug using backhoes, and dump trucks remove excavated dirt. Trench depths rarely exceed 30 feet. Depending on soil conditions or trench depth, sheet piles or trench boxes might be used to reinforce the sides of the trench. When the trench is completed, workers lay new pipes or repair existing pipes and refill the trench with gravel bedding material.

When work is done, the area gets a temporary paving and workers then move on to do another section. Permanent pavement is put down after construction to restore the entire area to its original condition or better.

Access to streets can be limited, and detours are common. In some cases, a road might be closed, though King County would preserve access for residents.

See also:

• Trenchless methods—tunneling and drilling
• Building or upgrading facilities
• Mitigation to minimize construction impacts

Updated: Dec. 6, 2005