GeoEngineering Centre at Queen's

Evaluation of Site Investigation Techniques for Geological Hazard Assessment for new Pipes installed using Trenchless Technology Techniques

by Afshin Mantegh, Masters of Science in Earth Science, Thesis, University of Waterloo, 2001

This thesis outlines site investigation requirements and hazards associated with new pipelines installed using trenchless technology methods. This thesis focuses on hazards encountered when using horizontal directional drilling (HDD) and microtunneling techniques. The reasons that these two techniques have been focused on are:

Greater consequences of work stoppage, more substantial delays and project over-runs;
Limited or very expensive access to retrieve jammed equipment;
Pipeline installation lengths are typically longer;
Pipeline diameters are typically larger; and
Higher project cost and duration.

The main goals of this research are: (1) to develop a methodology for identifying geological hazards associated with microtunneling and HDD construction methods, (2) to assess site investigation techniques currently used in different ground conditions, and (3) to define critical factors that impact project costs. To achieve the above goals, a survey questionnaire was developed and distributed as part of the research project. In addition, a literature review on HDD and microtunneling projects was conducted to provide additional data.

The survey data was analyzed to identify the potential geological hazards for HDD and microtunneling. A compilation of geological hazards encountered along with scoring of severity of these hazards is provided in this research. In addition, site investigation techniques commonly used by practitioners were evaluated using the data obtained from the analysis. To estimate the costs associated with geological hazards, the important cost factors that are believed to impact HDD and microtunneling operations were assessed as well.

Areas for future work consist of the development of cost profiles for different stages of proposed site investigation programs, as well as methods for assessing the effectiveness of site investigation, and the improvement of hazard assessment for other new pipeline installation methods such as moling, pipe ramming, pipe jacking and auger boring.

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