The U.S. Army Research and Development Command Acquisition Center has awarded a $62 million contract to a joint venture of Tetra Tech Inc. and Belcamp, Md.-based STEM International Inc.

The five-year contract includes technical services support to the acquisition center at its Aberdeen Proving Ground headquarters in Maryland as well as eight other chemical weapons sites nationwide.

Tetra Tech has done similar work for the acquisition center, in addition to the proving grounds in Colorado, Indiana, Oregon, Utah and Arkansas.

Financial terms of the deal were not disclosed.

Shares in Tetra Tech were down 3 cents to $15.37 in afternoon trading Friday.