Project: Artificial reef between the Tordera River and the Cape of Tossa

The project involved the construction of an artificial reef, composed of 305 deterrent modules, intended to obstruct illegal bottom trawling between the mouth of the Tordera river and the cape of Tossa, which implied the protection of 1,267 hectares of coastline

The reef consists of three zones, with areas of approximately 315 hectares, 300 hectares and 553 hectares respectively. Within these areas, the modules make up 12 polygons of symmetrically staggered protection, forming 3 rows in one zone and 2 rows in the other two zones. The longitudinal separation between modules in the same row is 100 m, and the latitudinal separation is 75 m between rows.
The 305 items are composed of a reinforced concrete base formed by two 300 cm long beams and sections measuring 100 x 35 cm, which intersect in their centres. The upper body, also of reinforced concrete and cylindrical in shape, is situated on top of the reinforced concrete base and has a diameter of 75cm and a height of 250 cm. Each module is equipped with a steel wire sling, with a diameter and a development that enable conveniently performing the tasks of loading and anchoring.
As the total weight of each module is 7.24 metric tons, their installation required a mid-sized merchant vessel equipped with two cranes with a capacity of more than 10 tons, which loaded these items at the Port of Palamós (Girona), then moving them to the corresponding area for anchoring.
In order for the final placement of the items to be carried out with the utmost accuracy, the ship had a computer system and hydrography programs with the capacity to inform it about the positions of the modules, navigation routes and pre-established destination points. In an effort to improve the accuracy of the positioning, a DGPS antenna was also installed on the crane, on the vertical axis of the module to be installed.