Keith Onslow

Tetra Tech UK Holdings Ltd. is a holding company, which engages in the provision of environmental engineering, technical, and consulting services. The company was founded on August 17, 2006 and is headquartered in Reading, the United Kingdom.

ARD, Inc. operates as an international development services consulting firm. The firm provides water resources and infrastructure, agriculture and economic growth, environment and natural resources, land tenure and property rights, democracy, governance and knowledge management services to international development customers. The company was founded by George C. Burrill and James R. Nolfi in 1977 and is headquartered in Burlington, VT.

Tetra Tech NUS, Inc. provides environmental, engineering, remediation and information technology consulting services. The company is headquartered in Pittsburgh. PA.

Tetra Tech India Ltd. engages in the provision of consulting, engineering, program management, and construction management services. The company was founded on April 4, 2017 and is headquartered in New Delhi, India.

Tetra Tech Tesoro, Inc. provides construction services. It also build schools, hospitals, and clinics for selected commercial and private clients. The company was founded on June 4, 1997 and is headquartered in Virginia Beach, VA.

INDUS Enterprise Solutions, Inc. provides information technology support services. Its services include software development, database design, system administration and maintenance, systems integration, software and network engineering, web services-enabled solutions, and information systems security. The company was founded by Aaron B. Floyd in 1986 and is headquartered in Vienna, VA

GeoTrans, Inc. provides environmental engineering and remediation services. It serves the automotive, aerospace, manufacturing, energy, petrochemical, transportation, and telecommunication industries. The company was founded in 1979 and is located in Sterling, VA.

Part of Tetra Tech, Inc., Hoare Lea Europe Ltd. is a British company founded in 2008 that is committed to making every client's vision a reality. The company is based in Almondsbury, UK. The company takes personal responsibility to achieve a shared vision and have the expertise, determination, and ingenuity to make it happen.

Part of Tetra Tech, Inc., Tetra Tech Canada, Inc. is a Canadian company that provides consulting engineering, program management, construction management and technical services. The company is based in Vancouver, Canada.