Imagine signing an agreement to buy a fancy car on layaway, then having to pay for an expensive valve job before your first installment is due. That's sort of what's happened in the case of the Central Arizona Project.

Although Arizona hasn't even begun repaying the $2 billion it owes the federal government for construction of CAP, major sections of the transdesert canal already have worn out and are being replaced at a cost of nearly $100 million.

Six siphons that carry the canal's Colorado River water beneath washes, freeways and rivers are being replaced or repaired after less than eight years of use.

Additional engineering problems are nagging CAP's largest pumping plant at Lake Havasu. A loud vibration caused by the design of the impeller that draws water into the pumps has officials worried that the pumping plant could experience a major failure.

The technical problems are just the latest in a litany of woes confronting CAP, whose water has become so expensive that demand for it has plummeted at the same time repayment for construction is set to begin early next year.

The largest siphon being replaced crosses beneath the Salt River about two miles west of the intersection of Shea Boulevard and State Route 87. Workers are installing 8,000 feet of 21-foot-diameter steel pipe that will carry canal water beneath the river and two Salt River Project canals.

The steel pipe manufactured by Phoenix-based Schuff Steel Co. replaces reinforced concrete pipe built by Peter Kiewit Sons' Company, an Omaha, Nebraska, construction outfit. The concrete pipe began to deteriorate even though each 22-foot section was wrapped with 21 miles of prestressed wire that was tightened to an incredible tension of 180,000 pounds per square inch.

"The wire corroded and they began to break," says Chuck Morfoot, a spokesman for the U.S. Bureau of Reclamation, which oversaw construction of the canal.

The bureau is attempting to recover the cost of replacing the siphon from Kiewit, claiming the company failed to conform to the contract requirements. In the meantime, Congress authorized an additional $100 million to pay for repair and replacement of the siphons. The siphons beneath New River and the Agua Fria River also will be replaced.

"The failure of the siphons was certainly unusual and unexpected," says Larry Dozier, an official with the Central Arizona Water Conservation District. The district--which is directed by an elected, 15-member executive board--operates the canal and will oversee repayment for its construction.

There was not much disagreement between the district and the bureau over whether the siphons had to be replaced. However, the two agencies clash over whether the Lake Havasu pumping plant must be repaired.

The bureau's Morfoot describes the pumping-plant problem as a "pulsation" that has no impact on the performance of the six 60,000-horsepower pumps, which each raise 500 cubic feet of water per second 825 feet from Lake Havasu to the canal.

"The water district has a problem with that; we don't," Morfoot says.
Dozier says the problem is an extremely loud vibration that so far has damaged small support components. The water district is concerned that simultaneous failure of several small components could significantly damage the plant.

"That could snowball into a major failure," Dozier says.
The noise also makes it difficult for workers, forcing them to wear extra ear protection, Dozier says. "The vibration adds an extra level of maintenance and diligence. We think it ought to be better than that," he says.

The bureau has agreed to fund two studies--costing $900,000 so far--to find a solution. The only conclusion to date is that the impellers must be redesigned. Dozier says it could cost $3 million to design and replace the impellers.

"We may spend a few million extra dollars to get it to work at the level of efficiency and the quality of performance we think we ought to have," Dozier says.