The objective of the work was to verify the HDD contractor’s design, methodology and calculations. Atteris reviewed the Contractor’s HDD installation procedure against requirements of the PRCI guideline for Installation of Pipeline by HDD. The review covered installation, overbend and operational stresses and the following aspects:
- Stress calculations
- Drilling fluid pressure assessment
- Proposed equipment for HDD operations
- HDD construction methodology.
The review identified geotechnical data gaps, which could present risk to the project, given actual geotechnical properties may vary from the values assumed for the design. Atteris recommended hydro-fracture analyses and a mud program in the event that the site conditions were found to be different from assumed values.