Tetra Tech, Inc. (NASDAQ: TTEK) announced today that it is one of five awardees for a $489 million indefinite delivery/indefinite quantity contract to provide program management and technical support for chemical weapons demilitarization programs at facilities across the United States. Under the U.S. Army Chemical Materials Agency (CMA) program and Integration Support V (PAIS V) contract, Tetra Tech will support the CMA and the Assembled Chemical Weapons Alternatives program for the next five years. Tetra Tech will also assist CMA in managing its non-stockpile chemical material program and chemical stockpile emergency preparedness program. Tetra Tech will provide a variety of program management, integration, and technical services to help support efficient destruction of chemical warfare and related materiel. This support includes environmental studies, design, monitoring, operations and maintenance, quality assurance, safety, and logistics support services. The PAIS V contract activities will help the U.S. Army to comply with international chemical weapons conventions and move towards ultimate closure of chemical agent disposal facilities and stockpile storage areas. About Tetra Tech ( www.tetratech.com) Tetra Tech is a leading provider of consulting, engineering, program management, construction management, and technical services. The Company supports government and commercial clients by providing innovative solutions to complex problems focused on water, environment, energy, infrastructure, and natural resources. With more than 13,000 employees worldwide, Tetra Tech’s capabilities span the entire project life cycle. 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.