Hydrovac Pipeline Exposure for Inspection & Repair
8-step process guide with equipment, safety, and cost information.
Pipeline exposure is the use of hydrovac excavation to safely uncover buried pipelines for integrity inspection, coating assessment, repair, or modification. This is a critical application in the oil and gas, water utility, and municipal infrastructure sectors where pipelines carry pressurized fluids and mechanical damage can cause catastrophic failures.
Inline inspection (ILI) tools, commonly called "smart pigs," identify anomalies along a pipeline's length that require direct visual inspection and measurement. Hydrovac excavation is used to create "integrity digs" at each anomaly location, exposing the pipe without damaging the protective coating or the pipe wall itself. This would be impossible with a backhoe or excavator.
Pipeline operators and their contractors perform thousands of integrity digs annually across North America. Each dig must be precisely located based on ILI data, excavated to expose the full circumference of the pipe, and restored after inspection. Hydrovac's precision and non-destructive process make it the only acceptable excavation method for this critical safety work.
Step-by-Step Process
Dig Site Identification
Review ILI data or engineering plans to identify the exact location requiring excavation. Use above-ground markers, GPS coordinates, and pipeline survey data to locate the dig site.
One-Call and Permissions
File 811 locate requests and obtain any required excavation permits. Coordinate with the pipeline operator and any other affected utility owners.
Site Preparation
Clear vegetation, set up safety perimeter, and position the hydrovac truck. Verify adequate boom reach and plan debris tank management for the project duration.
Excavation to Pipeline
Begin hydrovac excavation from the surface, removing overburden soil until the pipeline coating or casing is reached. Reduce water pressure as you approach the pipe depth.
Circumferential Exposure
Carefully expose the pipeline around its full circumference and along the required length. Remove all soil from the pipe surface without damaging the protective coating.
Inspection and Assessment
Perform the required inspection work: visual assessment, coating evaluation, ultrasonic thickness measurements, or other non-destructive testing. Document findings per the operator requirements.
Repair (If Required)
If defects are found, perform repairs including coating restoration, sleeve installation, or pipe section replacement per the operator repair procedures.
Backfill and Restoration
Replace padding and backfill materials per pipeline operator specifications. Compact in lifts and restore the surface. Document the final condition of the site.
Equipment Recommendations
- Large hydrovac truck (12-15 cubic yard tank) for deep, full-circumference excavation
- Fan-tip nozzle for gentle soil removal near pipe coating
- Extended boom (20+ feet) for deep pipeline access
- Heated water system for winter pipeline integrity digs
- Pipe support equipment to prevent stress on exposed sections
Safety Considerations
- ⚠Verify pipeline product and pressure before excavation
- ⚠Maintain safe standoff from pipeline during excavation
- ⚠Use low water pressure near the pipe to protect coating
- ⚠Follow pipeline operator safety requirements for hot work and confined space
- ⚠Have emergency response plan for pipeline release scenarios
- ⚠Monitor for H2S and other hazardous atmospheres at gas pipeline sites
Cost Factors
- ●Depth of pipeline (deeper = more excavation volume and time)
- ●Length of exposure required
- ●Access road conditions and distance to paved roads
- ●Soil conditions (rocky soil, high water table, contaminated soil)
- ●Right-of-way restoration requirements
- ●Winter conditions requiring heated water
- ●Number of digs per mobilization
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