Building a wastewater treatment plant in SilvoutaHe moves forward from the starting box in Santiago de Compostela. Nine construction companies, many organized as joint ventures, submitted bids for the construction contract aimed at creating a Wastewater Treatment Plant (WWTP). The tender carried a tax-free budget of 63.67 million euros and an estimated value of 66.42 million euros.
Last summer, the Board of Directors of the State Trading Company Aguas de las Cuencas de España Acuaes reactivated this tender, drawing interest from the leading construction and infrastructure firms in Spain. Firms such as Ferrovial, FCC, Acciona, Sacyr and CombedIn formed joint ventures among intra-group entities, with the top three ranks rounding out the list fourth. Galician companies joined UTE Extra, Lantania, and question, OHLA along with Thorn Hydraulic Works and ASOGA, COPASA and Global Omnium, GS Inima and St. Joseph. The Contract Board then asked Extraco to correct an error in the Single European Contract Document, while Dragados noted that the declaration of the group did not match the pattern required by the specification.
Re-tender
The current competition backed by Acuaes marks the second tender in a single year. According to El Correo Gallego from the Prensa Ibérica group, which owns Prensa Ibérica and is based in Galicia, the previous tender was awarded in 2021 to Drace Infraestructuras and Vías y Construcciones, subsidiaries of the ACS Group. The inflation crisis and rising construction costs interrupted the process, though the firms attempted negotiations for a global price increase with Acuaes, the Xunta de Galicia and the Santiago City Council. Successful bidders withdrew when costs rose beyond a threshold, a situation that allowed Acuaes to re-tender the works. ACS returned, this time with a different subsidiary, Dragados, instead of Drace and Vías y Construcciones.
Offers remain open until October 10, and the final winner may not be clear until the end of the year, according to the State Tender Portal. Packages 2 and 3 will not be issued until October 25 and December 5 respectively; the provisional award, followed by the final decision, has been delayed by several weeks. The project timetable estimates an implementation period of 27.5 months, suggesting the new treatment plant could become operational around mid-2026.
new cleaner
If the construction progresses as planned, Santiago de Compostela will complete one of its largest infrastructure projects in nearly three decades. The project origins trace back to the 1990s when a European directive required towns with more than 15,000 inhabitants to operate a wastewater treatment system. The capital of Galicia, along with 38 other Spanish towns, faced sanctions from the European Union Court of Justice due to noncompliance.
After exploring options for a new facility, the decision was made to expand the existing plant. Once renovations are complete, the facility will enter service with a capacity to purify water for a population of 277,000. The new tender specifications indicate it will be able to pre-treat the entire flow from the Sar River outlet during heavy rain, including primary treatment, rainwater treatment, and a secondary biological treatment using activated sludge.
Approximately 65 percent of the project will be funded by Acuaes through the European Union Next Generation Recovery, Transformation and Resilience Plan, with Aquas de Galicia contributing 10 million and the Santiago City Council covering the remaining portion. To secure the European capital and advance the project, the responsible company must complete the treatment plant works by the maximum date of 2027.