Tender for The object of the contract is the execution of the works described in the "project for the recovery and improvement of the ecological state of the Ripoll river along its course through Sant Feliu del Raco". The project includes, among other things: - removing the waste and inappropriate elements present in the river as well as along its banks. - - eliminating alien and invasive species. - reducing the impact of the wastewater from the wastewater treatment plant. - re-naturalizing the space, creating the conditions for the degraded habitat to be recovered and to reach the habitats appropriate for the area. - improving the quality of the riverine forest by increasing the surface area and quality. - improving the physicochemical parameters of the waters. - improving the biodiversity of native flora and fauna. - improving the landscape of the area. - promoting and making known the natural values of the area. The works planned in this project involve improvements to existing stretches or spaces, and in no case does it imply duplication of tasks already carried out previously. The following summarizes the works carried out in the project of "recovery and improvement of the ecological state of the Ripoll river along its course through Sant Feliu del Raco in the municipality of Castellarnau del Vallès" 1. Previous works: arrangement and creation of access to the riverbank, elimination of alien species 2. Habitat improvement: creation of vegetated deflectors, planting of excavated surfaces, installation of shrub hedges, collection of plant remains with wool blanket, finishing of the surroundings 3. Maintenance: elimination of the regrowth of alien species, repairs to the area of plant remains collection