Civil engineers apply mathematics, physical sciences, and fundamentals of engineering mechanics to plan, design, and supervise the construction of roads, buildings, airports, tunnels, dams, bridges, water supply and treatment systems. They are also involved in projects to improve the environment by designing solutions to air pollution, waste water treatments, and soil contamination remediation. Major specialties within civil engineering are: structures, geotechnical engineering, water resources, transportation, environmental engineering, and construction. Civil engineering graduates typically work in consulting firms, city and county public works or highway departments, state department of transportation, construction, and concrete and steel product industries. Many civil engineering graduates manage facilities for large corporations such as Hormel Food and utility companies such as Xcel Energy. Some civil engineering graduates have their careers in other fields such as aerospace, medicine, and law. Others may work in research and development, and teaching. Most civil engineers hold supervisory positions such as project engineers. Many civil engineers hold administrative positions, from city engineers to commissioner of state department of transportation.