Tetra Tech Awarded $40 Million Environmental Management Project at Former Army Ammunition Plant

(PASADENA, Calif., Jan. 5, 2006) -- Tetra Tech, Inc. (NASDAQ: TTEK) announced today that is has been awarded a $40 million project with a private developer, Sunflower Redevelopment, LLC, for environmental management of contaminated property at the former Sunflower Army Ammunition Plant in De Soto, Kansas. The property was formerly used by the U.S. Army to manufacture propellant during World War II and subsequent conflicts. Tetra Tech will provide environmental consulting and engineering services throughout the building demolition and decontamination, soil remediation, and site closure processes. The remediation work is part of a larger property revitalization and redevelopment effort. The project is expected to last up to seven years. About Tetra Tech (www.tetratech.com) Tetra Tech is a leading provider of consulting, engineering and technical services. With over 7,500 associates located in the United States and internationally, the Company supports commercial and government clients in the areas of resource management and infrastructure. Tetra Tech's services include research and development, applied science and technology, engineering design, program management, construction management, and operations and maintenance. Any statements made in this release that are not based on historical fact are forward-looking statements. Any forward-looking statements made in this release represent management's best judgment as to what may occur in the future. However, Tetra Tech's actual outcome and results are not guaranteed and are subject to certain risks, uncertainties and assumptions ("Future Factors"), and may differ materially from what is expressed. For a description of Future Factors that could cause actual results to differ materially from such forward-looking statements, see the discussion under the section "Risk Factors" included in the Company's Form 10-K and 10-Q filings with the Securities and Exchange Commission. Contact: Tetra Tech, Inc. Mike Bieber, 626-351-4664

Source: Tetra Tech, Inc.
Date: Jan 5, 2006