REI will join the Technical Support Services business segment of Tetra Tech.

Tetra Tech chairman and CEO Dan Batrack said the company has strong capabilities in water resources and front-end environmental permitting for oil and gas projects, while REI’s pipeline planning and engineering credentials are among the strongest in the United States.

"Together we can offer the rapidly growing shale oil market more comprehensive services. We are pleased to welcome all REI employees to Tetra Tech," Batrack added.

REI’s current clients are located in the Bakken and Niobrara shale oil regions.

Tetra Tech provides consulting, engineering, program management, construction management, and technical services.

REI provides planning, engineering, and construction management services for crude oil and natural gas production, midstream and mainline pipeline/facilities, and transmission projects.