Construction of a fourth levee to consolidate the river flow at the headwaters of the river Mosoll in Lleida

Located in the region of Solsona, the river Mosoll is a tributary of the Cardener. Its headwaters, located in the municipality of La Coma i la Pedra, are becoming eroded, and it is necessary to build a fourth perpendicular retention dyke to guarantee the hydrological settlement of the mountain terrain to slow the erosion. The works cover a 34-hectare catchment area and include three distinct stages: the access road, the construction of the levee and other works.
The access road to the third levee was reconstructed for ease of operation in the construction site area. In this phase, the existing vegetation was removed, the box was excavated and a 20 cm thick gravel base was laid to prevent excess mud. Once the work had been completed, the slope was restored to its original state. In addition, a small breakwater wall measuring 25 m long by 3 m high was built to strengthen the last section of the road before the third levee and thus allow the reconstruction of the rear box.

The river was diverted, and the foundations laid for the construction of the fourth levee. Subsequently, the lateral anchors were excavated, and the levee was built using gabions.
The new levee has the following dimensions:
- Height: 6 m.
- Crown width: 1 m.
- Base width: 9 m.
- Drainage section (trapezoidal), height of abutments: 1 m; base: 40 m.
- Upstream facing slope: vertical
- Vertical angle of downstream face: 45º
- Foundation width (gabions): 1 m.

Finally, the access road was repaved with concrete and all surplus material was removed.