William Paul Aitken

Capita Corp. provides financial services. It offers investment management and advisory services. The company is headquartered in Livingston, NJ.

Applied Science Associates, Inc. provides science and technology solutions. It offers consulting, environmental modeling, and application development to clients. The company was founded in 1979 and it is headquartered in South Kingstown, RI

RPS Mountainheath Ltd. provides laboratory analysis services. The company is headquartered in Abingdon, the United Kingdom.

Part of Tetra Tech, Inc., RPS Energy Ltd. is a British company that engages in the extraction of petroleum and natural gas. The company is based in Abingdon, UK. RPS Energy was founded in 1979.

Nautilus Ltd. provides classroom and field based geoscience and engineering training to the oil and gas industry. Its subject areas include geophysics, seismic interpretation, structure and tectonics, basin analysis, and reservoir development. The company was founded in 1999 and is headquartered in Hermitage, the United Kingdom.

Part of Tetra Tech, Inc., RPS Ireland Ltd. is a British company that provides engineering services. The company is based in Belfast, UK. RPS Ireland was founded in 1987.

Part of Tetra Tech, Inc., RPS Energy Consultants Ltd. is a British company that completes environmental impact assessments and facilitates environmental approvals by identifying, managing, and offsetting negative impacts. The company is based in Abingdon, UK and was founded in 1996. The company also provides planning, design, and project management services for new build data center construction projects and the upgrade or expansion of existing data infrastructure.

Part of Tetra Tech, Inc., RPS Group US Holdings Ltd. is a British company that provides survey operations and consultancy services to the water industry. The company is based in Abingdon, UK. The company was founded in 1995. RPS Group US Holdings was acquired by RPS Group Ltd., part of Tetra Tech, Inc. from January 23, 2023 on April 17, 2002 for $4.29 million.

WTW & Associates Ltd. provides technical services in oil and gas exploration projects. The company was founded on January 9, 2002 and is headquartered in Abingdon, the United Kingdom.

Paras Ltd. provides information management and strategy consultancy services to the energy sector. The company was founded by Hamish Angus Munro Wilson in 1993 and is headquartered in Abingdon, the United Kingdom.

Part of Tetra Tech, Inc., RPS Consulting Services Ltd. is a leading professional services firm that defines, designs, and manages projects across 6 sectors. The company is based in Abingdon, UK. RPS provides GIS and spatial intelligence capabilities and geomatics expertise in planning, risk mapping, natural resource management, and 3D visualization. Founded in 1979, the British company specializes in light rail, rapid transit, and freight rail initiatives.

Part of Tetra Tech, Inc., RPS US Holdings Ltd. functions as an investment holding British company. The company is based in Abingdon, UK and was founded in 1990.