 When World War II threatened tropical sources of natural latex for rubber , Sarnia was selected as the site to spearhead development of synthetic petroleum @-@ based rubbers for war materials , and Polymer Corporation was built by Dow Chemical at the request of the Government of Canada . Large pipelines bring Alberta oil to Sarnia , where oil refining and petrochemical production have become mainstays of the city 's economy . Shell Canada , Imperial Oil , and Suncor Energy ( Sunoco ) operate refineries in Sarnia . Large salt beds found under the city became a source of chlorine and other significant ingredients which contributed to the success of Chemical Valley . Chemical companies operating in Sarnia include NOVA Chemicals , Bayer ( Lanxess and H.C. Starck ) , Cabot Corporation and Ethyl Corporation . 
