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CARIBBEAN BUSINESS
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.
For further information please contact www.casiano.com
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