Abstract

Engineering-geologic evaluations of conditions, many of which constitute some form of natural hazard along the alignment of the proposed Kern River natural gas pipeline, were conducted to provide a basis to (1) reduce the risk of damage to the pipeline which could result in a threat to public safety, (2) reduce the owner’s exposure to loss of pipeline function (i.e., economic loss), and (3) comply with mitigation measures required by the Federal Energy Regulatory Commission (FERC) as part of the project Final Environmental Impact Statement (FEIS). The FERC developed 156 measures to mitigate environmental impacts related to the proposed pipeline. Of these, 17 pertained to geology and geotechnical engineering. Specific scientific and engineering studies were conducted to address design issues related to avalanches, volcanic eruption, fault rupture, liquefaction, slope instability, hydrocompaction, subsidence, springs, shallow ground water, and stream crossings. The most major fault crossed by the pipeline in Utah is the Wasatch fault zone. This fault is crossed a short distance north of down town Salt Lake City, within about 100 m east of the north-bound lanes of Interstate Highway 15 in an area of inactive gravel mining. The fault displaces Tertiary conglomerate against Quaternary sand and gravel. The steep slope along the pipeline alignment and the proximity of the fault crossing to anchor points (bends and bores) provided a particular challenge to design the pipe to withstand surface rupture of about 3 m.