Using the Alternative Delivery CMAR Method to Reline Two 12-ft Diameter Steel Pumping Plant Discharge Pipes and Discharge Manifold Piping at the Central Arizona Project

摘要

The Central Arizona Project (CAP) recently completed relining two 12-ft diameter steel pipes and associated manifold systems at the Mark Wilmer Pumping Plant on Lake Havasu in western Arizona, using the construction manager at risk (CMAR) project delivery method. The Mark Wilmer Pumping Plant withdraws about 1.6 million acre-feet (ac-ft) of water each year from the Colorado River and via six pumps lifts the water through two 12-ft diameter steel pipes about 850 ft to the Buckskin Mountain Tunnel. The pumps are arranged in two-sets of three units which allows isolation of three pumps, a single manifold, and a single discharge pipe for maintenance while still operating the other three units and associated valves and piping. The two 144-in diameter steel discharge pipes are each about 2,300 ft long with slopes that vary from about 9° to 45°. The discharge pipes and manifolds were installed with the construction of the pumping plant in the early 1980s, and the pipes and manifolds lined with a hot-applied-cold-tar-enamel (HACTE) in 1982. In 1986, the plant was commissioned and has been moving water for over 30 years. In 2016, the right pipe and manifold was relined, and in 2017 the left pipe and manifold was relined. As part of CAP's ongoing asset management program, the manifolds and discharge pipes have been inspected multiple times, and while it was apparent the HACTE was failing, CAP performed spot repairs of the lining as outages and internal man-power allowed. In 2012, it became evident the lining had reached its end and more than just spot repairs would be required to protect the integrity of the steel pipe. A project was developed to remove the HACTE and replace it with a modern coating system. Due to the physical extremes of the work and short outage window, it was decided to use an outside contractor to perform the work, and rather than use the traditional design-bid-build delivery method, CAP decided to use the CMAR approach. This paper will examine the initial development of the project surrounding the decision to use CMAR, outline the contractor selection process and the pros/cons surrounding that process, discuss the role the selected contractor played in the design (pre-construction services) of the new coatings system, then look at the development (negotiations) of the guaranteed maximum price (GMP), and finally review the delivery of the project. A brief discussion of CMAR versus design-bid-build and how the CAP approaches each will also be included.