The contract was awarded by the government of Costa Rica, through the Costa Rican Institute of Aqueducts & Sewage Systems, and is worth US$45m. The contract includes the facility's commissioning, technology transfer and assistance with operation and maintenance.
Construction is expected to take 30 months while the technology transfer and assistance with operation and maintenance will continue for a further 18 months.
Los Tajos will be Costa Rica's biggest wastewater treatment plant (WWTP) and Acciona Agua's first project in the country. The design is for a primary WWTP with full sludge capacity for an average daily flow of 2.81m3/second and a maximum daily flow of 3.45m3/second in its first phase. The plant will service 65% of the metropolitan area of San José, home to more than 1.6 million people.
The Los Tajos WWTP is the cornerstone of Phase I of the San José environmental improvement project, a programme aimed at the refurbishment and extension of the more than 360km network of collectors and secondary sewer networks. The government will invest US$290m dollars to reduce the amount of untreated wastewater from the current 20% to 0.1%.
In Phase II, the Plan will clean up the Tárcoles River basin, reducing public health risks and pollution levels in the region's aquifers. It will also prepare the capital for its expansion over the next few years.
Acciona Agua was chosen in an international tender marked by strict economic, technical and environmental requirements, given that the San José Environmental Improvement Project is backed by an international cooperation loan from the Japanese Bank for International Cooperation.