Desalination Serves Coastal Argentine City

When a series of water crises in 2014 disrupted conventional utility services in the coastal Argentine city of Caleta Olivia, the city needed a way to ensure an uninterrupted water supply.

The federal government looked to RWL Water for the expertise to create a reverse osmosis desalination facility to deliver fresh drinking water to the public.

Although water scarcity is an ongoing problem for the entire province, the estimated 80,000 residents of Caleta Olivia and another 25,000 residents in outlying areas were particularly affected by the regional infrastructure failures that disrupted the delivery of fresh water.

Groundwater was not an option, as local aquifers had been either depleted or contaminated. Although the area continually suffers from water stress, it does have a ready supply of seawater.

The area’s officials and public were familiar with RWL Water and its executives well before the crisis occurred, said Adrián Godoy, RWL Water business developer. The company had made several presentations on reverse osmosis desalination systems in government and public forums, and had also built a desalination plant in nearby Puerto Deseado.

System Under Pressure

Several structural and mechanical failures in the existing water delivery infrastructure precipitated the project. First, the Jorge Carstens Aqueduct failed. But, Godoy said problems have existed from the old system’s first day of operations. The greatest of these is caused by the difference in altitude (about 200 meters) between Caleta Olivia and the town of Comodoro Rivadavia. This difference causes almost 300 psi of pressure in the delivery pipe of the water link between the cities.

Godoy explained that because of the pressure, fixing a leak requires draining the entire pipe. When repairs are completed, it takes a minimum of 24 hours to restore service. “These problems increase during the summer season because the aqueduct’s flow is lower,” Godoy said. “When water consumption increases, it is impossible to supply enough drinking water for the two largest cities served by the aqueduct — Comodoro Rivadavia and Caleta Olivia.” These cities serve around of 100,000 residents with water. With the original conduits failing repeatedly, replacements were made.

Several mechanical failures at the system’s pumping stations also caused problems, and repairs typically were lengthy. Godoy said that several times three of the system’s four pumps failed. Although designed with stand-by pumps, this necessitated a reduction to between 30 and 40 percent of normal water flow to keep the fourth pump from failing.

Adding to the challenge was population growth. More people were coming to Caleta Olivia to work in the nearby oil fields, which are considered some of the most important in Argentina.

According to a government document, problems extended beyond disrupted water service. Sewer backups related to the system’s failure forced closure of schools for 60 days in 2013.

Water Emergency Declared

When a recent leak was repaired, water delivery pipes failed immediately. Between February 5 and 25, 2014, there was no water throughout Caleta Olivia and residents took to the streets in protest.

“The government officials made commitments to the population, like reconstructing pipes in the city to avoid leaks, to build storage tanks and to study alternatives to produce drinking water,” Godoy said. “The army was involved because they had emergency reverse osmosis water treatment plants able to produce drinking water using the wells around the city.”

Local groundwater is brackish, with a high salt content that makes it challenging to treat.

“Because of these problems, the provincial government decreed the water crisis in the city of Caleta Olivia and began to make plans to permanently eliminate these problems,” said Godoy.

A water emergency was declared for the entire city on February 15, 2014. RWL Water executives, including Godoy, were in the streets alongside the protesters, discussing desalination as an option for the city. “In talking with them, we learned there were doubts about the cost of the plant, maintenance, and energy consumption,” Godoy said. The people and government officials did not want to install a desalination plant on which they would be unable to pay the maintenance cost.

When the hydric crisis was declared in February 2014, RWL Water was able to present a complete project to provide drinking water to the city, including suggestions about the best place to be installed.

Bringing Local Expertise to Solution

RWL Water was familiar with the area and the water challenges, having built a similar desalination facility in Puerto Deseado, which is in the same province. Like the Puerto Deseado plant, the one in Caleta Olivia uses the same seawater desalination technologies and components, including ultrafiltration membranes for pretreatment, as well as an ultraviolet system to kill bacteria, energy recovery technologies to reduce power consumption, and remineralization as the final water polishing step.

The Caleta Olivia plant will provide 12,000 cubic meters a day of drinking water, or 150 liters a day per person for a projected population of 80,000. Individual modules allow for future expansion. The plant is designed so it can be expanded by a capacity of 3,000 cubic meters of water a day with each additional module.

The US$35 million project, funded wholly by the government of Argentina, should be complete and operational in the fall of 2015. The staff of Servicios Publicos Sociedad del Estado, the plant operator, will receive operation and maintenance training from the RWL Water technical staff.