Daylighting Utilities with Hydrovac: Complete Guide
8-step process guide with equipment, safety, and cost information.
Daylighting is the process of exposing underground utilities to daylight for visual inspection, verification, or to facilitate maintenance and repair work. While the term is sometimes used interchangeably with potholing, daylighting typically refers to creating a larger excavation that provides working access to the utility, not just a small verification hole.
Hydrovac daylighting is the safest method for exposing buried infrastructure because the pressurized water and vacuum system cannot damage properly installed utilities the way a backhoe bucket or trencher blade can. This is especially critical when working around gas lines, fiber optic cables, and high-voltage electrical conduits where a mechanical strike could cause explosions, widespread service outages, or electrocution.
Engineering firms, utility companies, and general contractors routinely specify hydrovac daylighting in their project plans when utilities must be exposed for visual condition assessment, joint inspection, coating evaluation, or to create working clearance for adjacent construction activities.
Step-by-Step Process
Pre-Excavation Planning
Review utility locate marks, engineering plans, and as-built drawings. Determine the required excavation size based on the work to be performed once the utility is exposed.
One-Call Notification
Submit a locate request through 811. Verify all utility owners have responded and marked their facilities before beginning excavation.
Access and Setup
Position the hydrovac truck with adequate boom reach. Establish traffic control if working in or near roadways. Verify water source and plan debris disposal.
Initial Excavation
Begin hydrovac excavation from the surface, working downward through layers of fill, native soil, and bedding material. Use lower pressure settings as you approach the expected utility depth.
Utility Exposure
Carefully expose the utility, cleaning soil from the top, sides, and if needed the bottom of the pipe or cable. Create enough clearance for the planned inspection or work activities.
Work Zone Preparation
Once exposed, shore or bench the excavation if needed for worker entry. Set up lighting, ventilation, and other support for the planned work.
Inspection and Documentation
Perform the required visual inspection, testing, or repair work. Document the utility condition with measurements, photos, and field notes.
Backfill and Restoration
Replace bedding material and backfill in lifts per specification. Compact each lift and restore the surface to original condition.
Equipment Recommendations
- Large hydrovac truck with 12-15 cubic yard debris tank for extended excavation
- Variable-pressure water system for working near different utility types
- Fan-tip nozzle for broad soil removal and straight jet for targeted work
- Extended boom (18-26 feet) for deep excavation access
- Adequate lighting for inspecting exposed utilities
Safety Considerations
- ⚠Verify all utilities are marked before beginning excavation
- ⚠Use reduced water pressure near known utility locations
- ⚠Follow OSHA excavation standards for worker entry into excavations over 4 feet deep
- ⚠Implement atmospheric monitoring for excavations near gas utilities
- ⚠Maintain shoring or sloping requirements for excavation walls
- ⚠Establish exclusion zones around exposed high-voltage utilities
Cost Factors
- ●Size and depth of required excavation
- ●Number of utilities to be exposed
- ●Duration of exposure (some work requires multiple days)
- ●Shoring and safety equipment requirements
- ●Backfill material specifications (flowable fill vs. native material)
- ●Surface restoration type and quality requirements
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