The Big Fill Slide - ASCE NoCo Branch Meeting on January 8
Please join us on Thursday, January 8 at 6 PM at the HomeRun Bar & Grill at the Blue FCU Arena in Loveland to learn about the Big Fill Landslide, a classic highway embankment failure that occurred on the western flank of Teton Pass in Teton County, Wyoming. This presentation from James Dahill with Wyoming Department of Transportation examines the complex geology and other factors that contributed to the catastrophic failure.
The Big Fill Slide
The Big Fill Landslide, a “classic” highway embankment failure, occurred on June 8, 2024 at MP 12.8 along Wyoming Highway 22 on the western flank of Teton Pass in Teton County, Wyoming. The failure occurred in a roughly 70 foot tall embankment section of the highway built in the mid to-late 1960’s. The failure is hypothesized as having occurred due to two primary factors; groundwater and aging infrastructure. A relatively fast winter snowmelt occurred in Spring 2024 allowing for a quicker-than-normal release of snowpack precipitation driven by average daily temperatures remaining above freezing for an extended period of time. This excessive, warm runoff period allowed for above-average groundwater levels to enable the aging, clayey embankment to lose its cohesive strength.
Wyoming Highway 22 roughly follows the boundary between two North American tectonic provinces. Mountains of Laramide age intersect with the Sevier foreland basin Overthrust Belt province. As a result, faults of various age are located along Wyoming Highway 22. The failed highway embankment traverses an isolated block of mapped, steeply dipping Cretaceous sandstone, siltstone and shale created by the southward thrusting Cache Creek Thrust Fault and the northward thrusting Jackson Thrust Fault. The Cretaceous strata are surrounded by various older Mesozoic and Paleozoic formations consisting of sandstone, limestone and shale. Boreholes drilled for the slide investigation and remediation design confirmed the geologic mapping. This presentation examines the complex geology and other factors that contributed to the catastrophic failure.
Presenter: James Dahill, P.G., Chief Engineering Geologist
James Dahill is a Professional Geologist with more than 36 years of experience in engineering geology and geotechnical investigations for the Wyoming Department of Transportation (WYDOT). He earned his Bachelor of Science in Geology from the University of Wyoming in 1987 and has advanced through progressively responsible roles since joining WYDOT in 1988. He currently serves as Chief Engineering Geologist, overseeing statewide geotechnical investigations that support highway design, construction, and infrastructure resilience.
James has more than two decades of experience in landslide assessment and stabilization design, with project expertise that includes geofoam embankments, ground anchors, horizontal drains, coupled shear piles, rock buttresses, and shear key systems. His work spans major corridors such as Snake River Canyon, the Moran Junction–Dubois corridor (US-26/287), WYO 70 over Battle Mountain, and the Casper–Muddy Gap/ Narrows Slide Repair.
He has completed extensive leadership and management training through the National Highway Institute, AASHTO/FHWA, WYDOT, Franklin Covey, and the Western States Coalition Leadership Academy. Licensed as a Professional Geologist since 1993, James also contributes to his professional and local community through service with the Cheyenne Engineers Club (President, 2005), Holy Trinity Catholic Church Men’s Association, the WyHy Federal Credit Union nominating committee, and more than a decade of volunteer ski patrol service.
Make an Impact – Sponsor an ASCE Northern Colorado Branch Event!
The ASCE Northern Colorado Branch is now welcoming sponsors for our 2026 monthly meetings and networking events, and we’d love to partner with your company! Your sponsorship helps support Colorado State University (CSU) students by covering their dinner costs and giving them the opportunity to attend for free — connecting them directly with local professionals. It’s a meaningful way to invest in the next generation of civil engineers while showcasing your company’s leadership and community commitment. We offer flexible Sponsorship Levels of $800–$1,000 and multiple available dates in 2026.
We’d be thrilled to feature your company as an upcoming sponsor and help you make a lasting impact in Northern Colorado’s engineering community.
To reserve your sponsorship or learn more, please email Stephanie Cecil.