The project must incorporate the findings of the feasibility study on the possibility of using horizontal directional drilling (HDD), a method that has already yielded positive results in other facilities such as Cala Tarida and Santa Eulària in recent years.

The Balearic Water and Environmental Quality Agency (ABAQUA) has launched the tender process for drafting the project of the new sea-land outfall that will serve the Maó-Es Castell Wastewater Treatment Plant (WWTP). This initiative falls under the agreement formalised in 2021 between ABAQUA and the municipalities of Maó and Es Castell, aimed at improving the sanitation and wastewater treatment systems of both towns. The agreement was renewed earlier this year.

ABAQUA

The proposal is based on a preliminary feasibility study commissioned by ABAQUA and delivered in May 2023, which thoroughly analyses the technical viability of constructing a new outfall using the horizontal directional drilling (HDD) method. The study outlines an optimal horizontal and vertical alignment, as well as the technical conditions required for implementation. One of the main advantages identified is that this technique avoids impact on the surroundings of the San Felipe Castle, designated as a Site of Cultural Interest, by eliminating the need for any intervention in or near its structure.

The technical documentation confirms that the existing outfall, built in the 1980s using materials such as concrete and fibre cement, is in poor condition due to the exhaustion of its service life. This deterioration has caused recurring malfunctions, prompting the need for its replacement.

The tendered service contract includes the development of the technical project required to define the new infrastructure and obtain all necessary permits. The design includes a 1,408-meter land-sea section using HDD, which minimises the occupation of the public maritime-terrestrial domain and significantly reduces environmental impacts. The possibility of shortening the final section by laying it directly on the seabed will also be analysed.

The base tender budget is €150,000 (excluding VAT), with a project timeline of eight months. The new outfall will ensure the continuity and reliability of the wastewater system, adapting it to current regulations and the future needs of the population.

Proposals may be submitted until July 9, 2025, at 7:00 p.m.