Page 399 - Trenchless Technology Piping Installation and Inspection

Inspection and QA/QC for Trenchless Installation and Replacement Methods 349

Inspection Guide for Horizontal Directional Drilling (HDD)

Preinspection Plan Review

Review geotechnical and soil reports.

Ensure DOT/agency facilities and nearby utility information are shown on the
plans and profiles and that the proposed alignment does not interfere with them.

Note the minimum cover above the top of the pipe and below the pavement surface,
or ground elevation (for longitudinal installations outside the influence of the
roadway) is _____ ft.

Note proposed pipe characteristics:
Pipe material _____________________.
Pipe diameter _______________ in.
Pipe wall thickness __________ in.
Overcut diameter ___________ in.
Backream dia. increase _______ in.

Ensure that the appropriate penetration angle and curvature rate are identified.

Review contingency plan.

Review job-site layout including: distance from access pits to roadbed, proposed
sheeting and bracing, materials storage and fabrication area, safety devices (barrels,
guardrail, etc.), and dewatering pit locations.
Review steel pipe coating requirements.

Note unique or special items / circumstances: ___________________

Construction Inspection

Verify traffic control is consistent with the permit requirements, one call service has
been contacted, and the DOT/agency permit is on-site.

Verify job-site layout is consistent with the approved plans, especially the alignment
of the pipe and machine.

Verify continuous monitoring records indicate bearing and grade of the leading edge
of the pipe is consistent with the approved plans, dewatering effort is satisfactory, soil
volume removed is consistent with projection, and that workers understand the
contingency plan.

Verify pipe characteristics are consistent with permit requirements.

FIGURE 8.23 Sample checklist for inspection of horizontal directional drilling
operations.