OSSA is the leading company in the Spanish market in underground projects in Mining, Civil Engineering tunneling (Road, Rail and Subway/Metro tunnels), Underground Hydraulic Projects, and Underground Hydro Power Plants. The company was founded in 1952. Through more than 70 years of continued specialization and innovation the company has earned an international reputation for designing and building the most complex underground projects, in difficult soil conditions, working in remote locations, with tight budgets and challenging project schedules. Our significant construction outputs and efficiency, along with the quality of our projects, are recognized worldwide. Civil Engineering Tunnel Projects. We have specialized in underground civil engineering projects: roadways, subways and railways. Hydro Power Tunnel Projects. Some of our landmark projects include seven major underground hydroelectric power plants, some of which have been among the largest in Europe (CH Cortes-La Muela in Valencia and CH San Esteban in Orense). We are active in the power plant tunneling industry internationally.. Mining Infrastructure Projects. We work for coal, copper, iron and potash mining corporations, and we have been involved in complex mine operation and mine infrastructure projects. We design and build vertical shafts, tunnels and adits, large caverns, underground workshops, and underground pump stations.