North Coast Superaqueduct

Highlights of our work on this project include the following:

• Performed a condition assessment that included internal and external pipeline inspection, hydrostatic testing, wire strain test, mechanical testing of wires, tests of hydrogen content in wire, and soil corrosivity testing
• Performed hydraulic and structural analyses
• Conducted mechanical, metallurgical, chemical, and petrographic testing of pipe constituent components
• Conducted chemical analysis of soil and groundwater
• Discovered pipes with low prestress level in the wire and performed tear-down inspection of low prestress pipe
• Determined failure to be result of the transient pressure event caused by sudden closure of a valve due to improper setting of the valve closure timing and inadequate prestress in manufactured pipe caused by breakage of wires during winding operations
• Designed repairs that consisted of post-tensioning the low prestress pipes with strands and applying a shotcrete coating on the post-tensioned pipe