Location: Vail, Colorado
Application: Pervious Backfill Behind Retaining Wall

The winter of 2007 -2008 was marked by heavy snowfall and record water levels. The slope between I-70 and US 6 in the Dowd Junction area in Eagle County, Colorado became saturated with the spring melt off and experienced a massive failure event. The slide blew out a portion of the lower retaining structure sending debris down onto US. The failure event forced the closure of US 6 and compromised the structural integrity of I-70 above the landslide. The safety of the traveling public is paramount and required the Colorado Department of Transportation (CDOT) to move quickly to design and secure a contractor for an emergency slope stabilization project.

CDOT contracted with a leading geotechnical construction company to install 260 high capacity concrete block anchors to tie back the active landslide and stabilize the slope. Once the slope was secure a few more construction elements were necessary to safely support I-70 and protect US 6. This work included a reticulated micropile wall drilled under I-70, a 6,000 SF mechanically-stabilized earth (MSE) wall, and replacement of the lower retaining structure along US 6 called a bin wall. This new bin wall was backfilled with pervious cellular lightweight concrete produced using the AQUAERiX foaming agent. Approximately 25 cubic yards of 35 pcf pervious cellular concrete was placed behind the new bin wall retaining structure.

Due to the close proximity of the retaining wall to the concrete block anchors installed to tie back the landslide, pervious cellular lightweight concrete was chosen as the backfill material to reduce the lateral earth pressure on the wall. Using a pervious cellular lightweight concrete material was ideal compared to other backfill materials because it allowed the slope to drain properly, which is key to reducing the potential for a future failure event. The cellular concrete was batched on-site and the ease of placement helped the contractor shave a few days off the construction schedule allowing them to re-open US 6 ahead of their Thanksgiving goal.