Geohazards have the potential to adversely affect the operation or integrity of an existing pipeline, or the routing, design, and construction of a proposed pipeline. Identifying, characterizing, evaluating, and if necessary, mitigating and monitoring geologic hazards have become critical steps to successfully and safely building and operating pipelines in the Appalachian Basin region of the United States. The recent, rapid expansion of pipeline construction and operation in the region, along with natural geologic and geographic conditions which are conducive to landsliding and ground subsidence, have resulted in a recent increase in geohazard-related incidences both during and post-construction of pipelines. As such, there is an increasing need to recognize, understand, and closely manage geohazards in this region, prior to, during, and post-construction of pipelines. This paper will provide an overview of essential tools that have proven most useful in this region, to identify, characterize, and ultimately mitigate and monitor potential geohazards. This paper will also provide insight on how to evaluate specific project needs and best-fit approaches and solutions for the project at hand, to reduce the operator’s risk. A case study will be presented from the Appalachian Basin region, including how a phased approach was used to assess and manage geohazards. The phased approach includes (1) Phase I Assessments, which consist of a regional-scale desktop assessment to identify, initially characterize, and qualitatively classify (e.g., low, moderate, high hazards) geohazards; (2) Phase II Assessments, which consist of a non-intrusive ground reconnaissance completed at targeted sites; and (3) Phase III Assessments, which consist of subsurface investigations such as drilling, test pitting, or geophysical surveys to further characterize specific hazards.
The information obtained from the phased approach can be used for the design of mitigation and/or monitoring, if deemed necessary. Overall approaches to selecting and utilizing best-fit mitigation and monitoring options, both during and post-construction, fit for the regional conditions and to the individual project, will also be discussed.