Horizontal directional drilling crossings
Expose existing facilities near proposed HDD alignments so the drilling team can review separation and decide whether the bore profile needs adjustment.
California Hydro Excavation / Utility Verification
Utility Potholing in California
Before a drill crosses an existing line or a trench reaches a crowded utility corridor, you need to know what is actually there. Utility potholing creates targeted test holes to expose buried infrastructure and verify depth, position and clearance at critical locations.
Existing utility exposureDepth & alignment checksHDD & trenching coordination
What is utility potholing?
A small opening that answers a specific question.
Utility potholing, sometimes called test-hole excavation or utility daylighting, exposes a buried pipe, conduit or cable at a selected location. The goal is to directly observe the facility before nearby underground construction proceeds.
Vacuum excavation can remove soil from a focused opening using water or air and suction. After the utility is exposed, its location, visible dimensions and depth can be checked using the project's required measurement procedures.
Surface markings guide the search. Exposure verifies the crossing.
Utility marks indicate approximate horizontal location; they do not establish the exact depth. A test hole verifies conditions at the point excavated, not every foot of the utility's route.
Where test holes matter
Utility potholing before critical underground work.
Focused utility exposure helps contractors plan the next stage using direct field observations rather than relying on drawings and surface marks alone.
Open-cut trench intersections
Verify the location and depth of buried utilities where new conduit, water, gas or electrical routes are planned to cross existing lines.
Electrical, fiber & EV projects
Check conflicts around proposed duct banks, communications runs, power services, charging equipment and underground tie-ins.
Design verification & site investigation
Confirm selected utility positions for engineering coordination, constructability review or documenting actual site conditions.
Information at the test hole
What an exposed utility can tell the team.
The value of potholing is the information gathered at the crossing. Agree on the required measurements and records before the holes are opened so the results can be passed to the designer, superintendent or drilling crew.
For formal Subsurface Utility Engineering (SUE) Quality Level A deliverables, excavation is only part of the process; survey, documentation and professional requirements must also be addressed.
01
Horizontal position
The utility's observed location in relation to the test hole, proposed route or established survey references.
02
Depth & elevation
Depth from an identified surface reference, plus elevation data if surveying is included in the agreed scope.
03
Utility type & visible size
Visible pipe or conduit size and material when they can be identified safely from the exposure.
04
Crossing clearance
The information needed to assess the proposed bore, trench or foundation against the observed utility position.
From marks to field measurements
How a utility potholing scope is organized.
Each project is planned around the utility owner, surface conditions, proposed test holes and the work that follows. Procedures must meet applicable safety and site requirements.
- STEP 01
Review & mark
Use project plans, utility information and appropriate 811 coordination to define the proposed test-hole locations.
- STEP 02
Expose carefully
Use an approved excavation method around the suspected facility while observing safe digging procedures.
- STEP 03
Verify & record
Check the exposed line and collect the measurements or photos included in the agreed scope.
- STEP 04
Protect & restore
Coordinate the handoff, backfill, compaction and surface repair according to project requirements.
For directional drilling crews
Potholing where the planned bore meets existing utilities.
For an HDD crossing, the test hole can help establish the observed utility elevation and position at a conflict point. The team uses that information, together with the design and safe clearance requirements, to evaluate the bore path.
Crossing verification / field decision
Before exposure
After exposure
Records and surface marks provide an estimated utility alignment. Depth may remain unknown.
The observed facility can be measured at the test hole to help assess the proposed crossing.
A single pothole does not verify the full length of a buried line. Additional test locations may be needed where its profile or alignment changes.
Request utility potholing
Send the crossing list and project details.
Clear field information helps define quantities, access, surface removal and the requested records. We can review your California project and discuss scope and availability.
Project location
Address, work area, traffic restrictions and truck or hose access.
Number of test holes
Estimated quantity, stationing and marked locations on plans.
Utility information
Known utility owners, locate status, crossing details and target depths.
Surface & restoration
Asphalt, concrete or soil conditions, coring, backfill and patching scope.
Deliverables
Photos, measurements, survey ties or formal reports required by your project.
Schedule
Requested date, site contacts, permits and construction handoff timing.
Utility potholing FAQs
Common questions before you dig.
What is utility potholing?
Utility potholing is the targeted exposure of an underground line at a selected location to verify its observed position and depth. It is often performed using vacuum excavation or another approved method before nearby construction.
Is utility potholing the same as daylighting?
They overlap. Potholing typically refers to a focused test hole for location and depth verification. Daylighting can also refer to exposing a larger section of buried infrastructure for inspection or access.
Does an 811 mark show the exact depth of a utility?
No. Surface marks generally identify an approximate horizontal position, not a confirmed depth. Potholing is used when the project needs direct verification at a particular crossing or location.
How many potholes are needed for an HDD project?
It depends on the crossings, utility density, bore alignment, owner requirements and uncertainty in the field information. Some routes require several test holes because one exposure only verifies one location.
Are utility measurements and restoration included?
Those deliverables should be defined in the quote. Measurement records, surveying, coring, backfill, compaction, disposal and paving restoration can be separate scope items depending on the project.
Can you review a utility potholing project anywhere in California?
Send the site address, approximate test-hole count, proposed dates and plans. California Hydro Excavation can review the request and discuss availability for that location.
California Hydro Excavation
Get a Project Quote
Need utility depth confirmed before construction?
Send your plans, crossing locations and requested field requirements. We'll review the scope and discuss next steps for your utility potholing project.