ANC Postmark Drive Outfall Emergency Assessment and Repair

Start Date: October 2014. End Date: June 2015

Project Location: Anchorage, Alaska

Early in the winter of 2013, Ted Stevens Anchorage International Airport (ANC) staff discovered that one of the airport’s major storm drain outfalls had collapsed.  The uncontained storm water runoff was causing significant bank erosion on the shores of Cook Inlet. Under our term contract with ANC, a CRW team quickly mobilized to visually inspect the system failure, and began to consider solutions. The team developed a  by-pass pumping system short-term solution, and performed a CCTV inspection of the partially collapsed 50-foot deep pipe to determine what options should be considered in the long-term solution. A geotechnical investigation was successfully conducted with limited access, allowing the team to develop repair alternatives, and design the recommended improvements. CRW’s repair designs continually evolved as utility locates, soils conditions, and environmental permitting developed. The project’s successful completion utilized innovative soils stabilization methods along with an in-situ storm drain structure and pipe repair methodologies. The design saved millions of dollars in excavation and backfill, and allowed one of ANC’s two major storm drain outfalls to remain operational during construction.

Services Provided

  • Survey and Mapping
  • Site Design
  • Snowmelt and Stormwater Treatment

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