The scheme is the first stage of a planned multi-million pound development over the next ten years which will include a second extension, east terminal pier and walkway, hotel and multi-storey car parking.
The expansion plans are designed to enable the airport to handle 10 million passengers a year.
The Hydrock team will be working on the initial scheme design with a view to releasing initial documents by the start of summer.
The west terminal extension will be a three-storey structure, incorporating a single storey basement, of predominantly concrete frame construction but with a steel frame to the front elevation.
Hydrock Project Director, Jerry King, said: “Bristol Airport is a significant gateway to Bristol and the South West and we are delighted to be involved in this prestigious project.”
Hydrock is working as part of the design team which includes McAlister Armstrong & Partners Ltd, Architects; Hulley and Kirkwood, Building Services; Ward Williams, Quantity Surveyors.