Method Statement for Construction of Non-Disruptive Road Crossing NDRC by HDD Drilling Method

Horizontal Directional Drilling (HDD) is a trenchless technique for installing underground utilities—like HDPE pipes—beneath roads and highways without disrupting surface traffic. A guided pilot bore is first created, then gradually enlarged (reamed), and finally the pipe is pulled through the bore. Minimal excavation—entry and exit pits only—keeps the operation clean, quiet, and quick.

 Method Statement

1. Equipment & Materials

• HDD rig, jet drilling head with water/bentonite tank, high-pressure pumps

• HDPE pipes, transmitter/receiver, reamer tools, towing head, swivel

• Welding machine, polymer extenders, and drilling fluids

2. Roles & Responsibilities

• Site/Project Manager: handles permits, inspections, coordination

• Project & QA/QC Engineers: maintain compliance, oversight, and documentation

• HSE Engineer: enforces safety standards, PPE, traffic control

• Drilling Lead & Civil Foreman: execute drilling, pit work, monitoring

3. Pre‑Construction Steps

• Secure permits & utility approvals; have approved drawings onsite

• Excavate and shore entry/exit pits (typically ~4 m × 4 m, depth per design)

• Use trial pits to locate utilities; expose footpaths or medians if needed

• Step or shore pits deeper than 1.5 m

• Plan traffic management (lane closures often brief, flagmen/signage)

4. Pilot Hole Drilling

• Drill ~70 mm pilot hole with high-pressure bentonite-water jet

• Typically, 40–50 L/min @ 30–60 bar—adjust to ground conditions

• Transmitter sends downhole position (depth, inclination) to receiver—records every ~3 m

• One operator “walks” the path above ground to guide the tool; brief lane closures ensure safety

5. Reaming Operations

• Upon reaching the exit pit, attach reamer tool(s) and begin staged enlargements

• Multiple passes, ending with bore ~1.2× the pipe OD

• Circulate drilling fluid to flush debris; pulling rods in/out helps balance geological changes

6. Pipe Installation

• Butt/fusion weld HDPE pipe lengths into one continuous string

• Connect towing head and swivel to the pipe bundle

• Pull pipe back while drilling fluid circulates to lubricate and maintain hole integrity

7. Drilling Fluid Management

• Bentonite slurry + polymers provides lubrication, stabilizes hole, carries cuttings, and forms filter cake

• Fluid volumes & pressures (pilot: 40–50 L/min @30–60 bar; reaming: 50–70 L/min @20–30 bar; pull-back: 40–60 L/min @20–30 bar) tailored per project

8. Testing & Quality Control

• Conduct mandrel/hydrostatic tests after pull-back to verify pipe integrity

• Keep detailed logs: drilling data, fluid properties, weld inspections, as-built alignment (depth, inclination, chainage)

9.  Reinstatement & Monitoring

• Backfill & shore pits; restore surfacing per specification

• Clean the site thoroughly; demobilize traffic controls

• Monitor road levels monthly for 6 months—report any settlement or discrepancies

10.  Health, Safety & Environmental Measures

• Provide PPE, barricading, signage, toolbox talks

• Monitor drilling-fluid pressure to prevent blowouts or washouts

• Comply with traffic authority guidelines; coordinate with police if required

• Control noise, dust, waste; avoid contamination of nearby services

  
  
  
  

 Benefits & Limitations

Advantages:

• No open trench, minimal traffic disruption, low noise

• Highly accurate directional drilling; flexible path alignment

• Environmentally friendly with little to no surface settlement

Considerations:

• Precision depends on alignment accuracy—tight tolerances needed

• Suitable for bore diameters typically under ~1,200 mm

• HDD rigs are capital-intensive; changing ground conditions may pose challenges

HDD-based NDRC offers a clean, efficient, and low-impact way to install utilities beneath busy roads. By following a structured approach—comprehensive planning, precise drilling, staged reaming, careful pipe pull-back, and detailed testing—you can deliver a safe and high-integrity crossing that preserves surface traffic flow and public convenience.

**The content of this article is taken from web open source. The blogs are intended only to give technical knowledge to young engineers. Any engineering calculators, technical equations and write ups are only for reference and educational purposes.