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Super Aqueduct Coming Online

by Lida Estela Rua

March 1, 2000
Copyright © 2000 CARIBBEAN BUSINESS. All Rights Reserved.

The Superaqueduct is expected to go online next month bringing 75 million gallons daily (MGD) of water from Arecibo to the San Juan metro area.

Puerto Rico Aqueduct & Sewer Authority (Prasa) Board Chairman Armando Vivoni said the final determination will be made once Thames Dick, the company which designed, constructed, and has a five year contract to operate and maintain the Superaqueduct, makes several test runs.

The project was 99.9% completed in September 1999 but a section of pipe broke during a test in Dorado and another broke later in Manati. A four-month long investigation ensued and Thames Dick is being fined $30,000 a day since Sept. 7 because of the delays. "The fines will be deducted from the money we finally pay them," Vivoni said.

Engineer Samuel Porrata, who is project director for the Super aqueduct from CSA Architects & Engineers, Prasa's consultants for the project, and engineer Anibal Camacho, Prasa Superaqueduct project manager, explained investigation findings concerning the pipe breaks. Vivoni, Porrata and Camacho are members of the Superaqueduct team, who, along with Thames Dick officials, are making the final evaluation before the green light is given for the water from Dos Boca's lake in Utuado finally makes its way to San Juan.

In the case of Dorado's Maguayo neighborhood, where two pipes broke and flooded several homes, it was human error. Pipe manufacturer, Atlantic Pipe, in Cataño, made a mistake in numbering two batches totaling 10 pipes. Superaqueduct prestressed concrete cylinder pipes are built to withstand a pressure ranging from 50 to 175 pounds per square inch, but the pressure in Dorado was 195 pounds per square inch.

The technical explanation given by the three engineers was that valves, which control the flow of water, must be closed to exact specifications to control the velocity so it does not exceed that for which the pipes were designed. If not closed properly, the pressure will be greater, causing a surge that sounds like "a water hammer," or the noise commonly heard in any closed pipe when it is suddenly opened. Vivoni said this was precisely what happened with the two pipes that broke in Dorado where the surge of pressure was 195 pounds per square inch, beyond specified capacity.

The problem with the Manati pipe was different. While it had been manufactured to withstand the correct pressure, the coating that covers the prestressed wires, which are precisely what gives the pipes its strength, had fallen off. This left the wiring exposed and caused accelerated corrosion.

The pipes, six feet high inside with an exterior diameter of seven feet, are placed in ditches 13 feet deep by 10 feet wide. Since the September mishaps, a team of experts has literally walked inside the 38 miles of pipe from the Arecibo filtration plant to the two tanks in Toa Baja, next to the Pepsi Cola plant. The team doing the investigation is made up of technicians from Prasa's Superaqueduct office, Thames Dick, and Atlantic Pipe.

"There were doubts concerning the misnumbered 10-pipe batch. All were dug up to check the coating and the wiring which proved to be fine," Vivoni said.

Vivoni said there is no problem with the Arecibo filtration plant, which has the capacity to process 100 MGD of drinking water from the Rio Grande de Arecibo, which is fed principally from Dos Boca's lake in Utuado. The plant has all the permits and is working properly, having already tested the gravity feed of water from Arecibo to Toa Baja.

The project has permits to process 75 MGD until a study is completed to determine how much water is needed in the Rio Grande de Arecibo to sustain fish, plants and other marine life, unaffected. The study, slated to take three years, has been underway for a year and a half. Until it is concluded, in mid-2002, [1.5 more years ends in 2001] only 75 MGD, not the full design capacity of 100 MGD, will be processed, Vivoni said. "To our knowledge, not only is the filtration plant working well but also all the other components of the project," he added.

Thames Dick receives a set amount during its five-year operational and maintenance contract and another amount that varies depending on how much water is produced. Vivoni said Thames Dick will have to negotiate with Compania de Aguas, the French subsidiary of Compagnie Generale des Eaux, which is operating Prasa on a three year contract, to determine how much water is needed.

"The operational and maintenance contract with Thames Dick stipulates an average cost of $10.5 million annually, in 1995 dollars, which, using the U.S. Corps of Engineers estimates, will increase about 3% per year," Vivoni said. The set rate of the contract includes payroll.

Vivoni said that even if there is a drought this summer, Puerto Rico will be able to face it without undergoing water rationing with the Superaqueduct in place and thanks to the dredging of Lake Carraizo. The dredging of Carraizo was completed last year at a cost between $48 million and $50 million. It will add 28 days to the existing number of days of water supply the lake had been able to produce. Lake Carraizo is the principal source of water for a major portion of the San Juan metro area.

There are still numbers to crunch so the final cost of the dredging has yet to be determined, Vivoni said. Another plus is that the Superaqueduct can generate its own power supply in case Puerto Rico Energy & Power Authority (Prepa) fails to provide adequate power.

The Superaqueduct cost $345 million. Vivoni said the project exceeded the original estimate of $305 million because of prolonged work stoppages and higher land costs. The project was taken to court by environmentalists and paralyzed for five months at a cost of $5 million "because workers and machinery rented must still be paid." Then came Hurricane Georges, which stopped the project for a month. "Land expropriation also turned out to be much more expensive than we had anticipated," Vivoni said.

This Caribbean Business article appears courtesy of Casiano Communications.
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