Mission: Trenching

Utility trenching is an unobtrusive way in which to locate and expose utilities. Conventional methods of digging with shovels and other mechanical equipment can be extremely risky around unprotected utilities. Although trenching is not as fast as mechanical methods, it is a much safer practice. Utilizing the trenching method can reduce or eliminate risk and can be less likely to cause costly problems associated with utility damages.

Trenching by vacuum excavation may be beneficial for a project if there are site and physical constraints such as walls or barriers, utility congestion that would make it difficult to dig with conventional methods, or site requirements set forth by the Owner.

Trenching Project Examples:

Physical Site Constraints
Crews were tasked with using vacuum excavation to excavate a new electric duct trench 24 inches wide and 30 inches deep, for a length of 265 feet.  Trenching was required by Washington Metropolitan Area Transit Authority due to multiple factors. There was extremely limited site access, with a 100-foot section behind the building being inaccessible by any heavy equipment. Multiple electric ductbanks, which provide power to the Metro trains, were in between the security fence and a high-voltage electric substation. The grounding system for the substation and trains were not to be disturbed or damaged in any way.

Additionally, there were other high-voltage electric and communication ductbanks containing fiber-optic cables in conflict with the proposed trenching. The electrical tie-in vault was also excavated to facilitate core drilling and installation of the new conduits.  This work was completed in nine working days, and moved enough soil to fill eight dump trucks.  The proposed electric duct was installed without incident.

Unknown Utilities
Crews were tasked with trenching for this project because rumors had circulated to the contractor that a high-level secure fiber optic duct had been installed along the shoulder of the road.  Utility-owner records showing the approximate location were not available for release for this duct, and multiple “Miss Utility” tickets were called in with no response from the Utility Owner.  The Contractor was attempting to install new Storm Sewer pipes for development of an adjacent site, and would be trenching approximately seven feet in depth across these “Secure” lines. 

Mid-Atlantic crews dug a slot trench for a length of 80 feet to a depth of seven feet through heavy clay, broken rock, and heavy groundwater conditions to clear the proposed storm line trench of any fiber optic cables.  The contractor ultimately installed the proposed storm pipes with no incident. This process took two full working days.

If you have questions, or think your project could benefit from trenching via vacuum excavation, contact the professionals at Mid-Atlantic Utility Locating.