Going-to-the-Sun Road
– FHWA
Glacier
National Park, Montana
Designed 7-retaining
wall modifications or replacements, including 2-avalanche-resistant
wall designs. Provided comprehensive geotechnical investigation
starting three years prior to the design effort. Established avalanche
thrust design loadings through extensive research of established
models and SNOWTEL data near the project. Wall types considered
and/or designed included micropile-supported reinforced concrete,
reinforced concrete supported by micropile foundation, rock-anchor
supported cantilever, Mechanically Stabilized Embankments (MSE), and
stone masonry gravity. Provided plan preparation and specification
review. Worked closely with FHWA design engineers. Design challenges
included estimation of avalanche thrust forces, maintaining historical
integrity, open traffic lane requirements, and construction access and
equipment loading. Provided inspection and consultation during
construction of our wall design at milepost 30.03. The Orion design
was subsequently used by the FHWA as a demonstration project in the
use of micropile technology.
McCracken's Bridge Reinforced Soil Slope - FHWA
Wise River,
Montana
Provided Reinforced
Soil Slope (RSS) geotechnical design and facing details using
inextensible welded wire to provide a 3/4:1 finished face at the
bridge abutment locations. The steep side slopes were required due to
limited horizontal distance between an adjacent snowmobile trail. Provided RSS design and details for both bridge abutments.
Analysis utilized a beta version of FHWA design software, in which Orion
Engineering provided development review at FHWA offices in Vancouver,
WA. The software followed FHWA Demonstration Project 82 "Mechanically
Stabilized Earth Walls and Reinforced Soil Slopes Design and
Construction Guidelines", FHWA-SA-96-071, June 1996 . A major
design challenge included the interaction of the RSS design with
vertical piles that were required to support abutment loads. Design
details included facing, reinforcement type and spacing, and vertical
pile interface.
Snowbowl Ski Area
Missoula,
Montana
Provided geotechnical
consultation regarding conceptual retaining wall and constructed
slopes for a 5-mile road-widening project on USDA Forest Service
Land. Presented conceptual design alternatives to federal agency
engineers and project managers for approval. Retaining
wall/constructed slope concepts included reinforced soil slopes (RSS)
with wire basket facing elements, gabion-faced mechanically stabilized
embankments (MSE’s), and rock buttresses. Design challenges included
steep terrain, unstable slopes, water drainage, and the owner’s
concern of sediment loading upon a nearby creek containing bull trout.
