Calling 811 is required before excavation in Colorado, but locate marks are not the same as a complete utility investigation. On a complex commercial, municipal or infrastructure project, the team may need to confirm the exact horizontal and vertical position of a known or suspected line before finalizing an alignment or starting excavation. That process is commonly called potholing or daylighting.
Potholing exposes a small area around a utility so the team can verify what is actually in the ground. It may use careful hand excavation or vacuum excavation, depending on the utility, site conditions and utility-owner requirements.
What 811 does—and what it does not do
Colorado 811 requires notice at least three business days before digging and tells excavators to use extra caution within 18 inches of a public-utility mark or flag. That process is essential for damage prevention. It does not locate every privately owned line, and painted marks do not always provide the depth, material, condition or exact configuration a project team needs for design and construction decisions.
That is where potholing becomes useful. It can confirm whether a line is where the records indicate, how deep it is, and whether it conflicts with a proposed utility, structure, roadway or excavation. It is a targeted investigation, not an excuse to skip the locate request.
When a project should consider daylighting
Positive location is especially valuable when the project includes:
- a proposed water, sewer or storm crossing;
- deep excavation near active utilities;
- a tie-in to existing infrastructure;
- limited right-of-way or congested utility corridors;
- an uncertain as-built record;
- a utility relocation decision; or
- a design that leaves little room to change grade or alignment in the field.
The Federal Highway Administration explains that subsurface utility engineering can combine surveying, geophysical methods and vacuum excavation to identify conflicts with planned work. FHWA also notes that the information can be documented for future design and construction use. On a civil project, that information can be far less expensive to obtain before the trench is open than after crews encounter an unanticipated line.
Potholing is part of coordination, not a stand-alone task
The value comes from what the team does with the result. Once a utility is exposed, document the location, elevation, utility owner, size and observed condition according to the project’s process. Survey information can then be coordinated with design drawings, proposed grades, utility profiles, shoring needs and construction sequencing.
For example, an existing water line may require a proposed storm line to change elevation. That change can affect trench depth, bedding, shoring, access and the order in which other utilities are installed. A good civil team turns the daylighting result into a buildable plan.
Protect the schedule and the people around the work
An unplanned utility conflict can delay excavation, disrupt public service, create a safety hazard and force redesign. Daylighting does not eliminate every risk, but it gives the team stronger information before a high-consequence activity begins.
633’s Colorado 811 guide covers the required call-before-you-dig process. This article addresses the next decision: when a marked or suspected utility needs to be positively located before the sitework sequence is committed.
633 Construction coordinates site utilities with excavation, grading, drainage, inspection and existing infrastructure. For a project with unknown lines, difficult tie-ins or a congested corridor, start the conversation with 633 early enough to turn field information into a workable plan.
