Western Australia Chapter

Geohazard Assessment for Critical Infrastructure Engineering

James V. Hengesh, P.G.

Engineering projects are susceptible to a wide range of geological and seismic hazards. Examples of these hazards include earthquakes, landslides, metastable soils, floods, volcanic eruptions, and other related phenomenon. Understanding the location, severity, and frequency of these hazards is of critical importance to selection of suitable development sites or asset corridors, as well as proper design of foundations and structural elements. Though systematic characterization of geological hazards is sometimes perceived as an added project expense, failure to recognize and mitigate hazards at an early stage can lead to schedule delays and substantial liability, as well as repair and business interruption costs. For example, the 760-km long Camisea pipeline system in the Peruvian Andes failed six times in the first 24 months of operation leading to millions of dollars in repair costs, 10’s of millions in business interruption costs, $50 million per year in geotechnical maintenance, several fatalities, and significant political “fall-out” due to NGO opposition.

The detail and extent of geohazard investigations vary greatly depending on specific project requirements and end-applications. For example, conducting a PSHA for a critical facility such as a nuclear power plant requires that extensive geological, seismological, geophysical, and geotechnical studies be performed to demonstrate site-suitability and to provide input for ground motion computations. Alternatively, onshore pipeline route selection can be quickly and efficiently supported through “desk-top” studies followed by visual inspection during aerial and ground reconnaissance to avoid or route around hazardous areas.

This presentation will draw on examples from several major projects to discuss development of seismic source models for seismic hazard assessments and to show how terrain analysis can help projects avoid major pitfalls.

Engineers Australia members participating in AGS technical sessions can record attendance on their personal CPD logs. Members should refer to Engineers Australia CPD policy for details on CPD types, requirements and auditing guidelines.