Arrow Creek Slide Repair
Near Stanford, MT
Kirk Spalding, PE
CHRONIC BENTONITE LANDSLIDES NEAR STANFORD, MT
In the fall of 2011, MDT decided to completely reconstruct the roadway located on Highway P-80 in the Arrow Creek drainage as a long term solution to its chronic landslide problems. Highway P-80 has required significant maintenance from on-going slides dating back to the 1950s. Seventeen landslides occurred above and below the roadway and the project was initiated to design and construct repairs to the slides.
NEVER BEFORE EMPLOYED IN MONTANA, THIS PROJECT COMBINES AN EXTENSIVE DRAINAGE SYSTEM OF CULVERTS AND SIDE-CHANNELS WITH THE INSTALLATION OF 504 ENORMOUS SOIL STABILIZATION ANCHOR BLOCKS.
Sanderson Stewart completed the road and R/W design for this approximately $15.5 Million, 2.2 mile project. The project includes installing 504 12’x12’x2’(thick) concrete blocks and anchoring them to underlying bedrock. There is also significant channel relocation/armament, flow dissipation structures, interceptor swales (on finished slopes), rip-rap outfalls and downchutes, ditch blocks, and other erosion control design measures. Large diameter pipes, including HDPE was installed along the finished slope to receiving drainage to prevent slope erosion, and often enter USBR dissipators, significant channel relocation and armament, Sanderson Stewart also provided construction engineering support.
“This is a once-in-a-career type of project, it is very unique.”