City: Haywood County
State: North Carolina
Owner: North Carolina Department of Transportation
General Contractor: Phillips & Jordan
Interstate 40 is a vital artery that links the industry of the Midwest with the business centers of the Southeast Coast. It was constructed in the early 20th Century by blasting through the mountains and using the subsequent shot rock as roadway fill. In a remote area of western North Carolina, I-40 parallels the Little Pigeon River.
In September 2004, hurricanes Frances and Ivan caused the Little Pigeon River to flood. The flood waters eroded the embankment below I-40 and sent one of the east bound lanes, along with the roadway shoulder, into the river below. The North Carolina Department of Transportation (NCDOT) considered this damage to be an emergency situation and needed to repair and reopen the damaged lanes as soon as possible.
The fix had to have a 100 year lifespan and had to be completed within 4 1/2 months without any disruption to the remaining traffic lanes of I-40. Schnabel won the contract with a proposed design that included two tied-back walls each consisting of 10 ¾” diameter micropiles and corrosion-protected tieback ground anchors installed through the existing rock fill into competent bedrock, concrete wales and reinforced shotcrete face. This design not only allowed Schnabel to satisfy the design criteria and overcome the access and space problems, it allowed them to take advantage of superior shotcrete placement skill in order to complete the project during the coldest months of the year and within the timeframe established by the NCDOT.
The final system consisted of 102 micropiles, 115 tiebacks, and 1,215 LF of concrete wales to support the 705 foot long landslide without disruption to the remaining lanes of I-40.