Oregon Zoo Train Tracks, Portland, Oregon

GeoDesign assisted Metro and the Oregon Zoo in evaluating the Oregon Zoo Train alignment with an eye toward restoring the historic train line. We identified potential geotechnical issues affecting the alignment with respect to soil conditions, existing wall conditions, and localized drainage.

Our scope involved a preliminary geologic hazard review, including:

• LiDAR-based slope gradient analysis
• discussions with Zoo maintenance staff for historical slide issues
• walking the full rail alignment to observe exposed soil, retaining walls, stormwater drainage erosion, and possible landsliding

We identified areas of concern on a GIS-based map inventory, which was used to triage areas in need of repair and to help the Zoo budget for these improvements.

GeoDesign also provided recommendations for contractors to use when designing repair of existing retaining walls or slopes.

Wall types considered included:

• mesh/anchor
• pile/mesh
• pile/timber systems
• soil nail with concrete facing