Engineering and construction group Costain has won a £30m deal to help upgrade a gas terminal on Britain's east coast.Independent oil & gas company Perenco has appointed Costain to provide engineering, procurement and construction services for the environmental upgrade of the Dimlington gas terminal on Humberside. The project involves upgrading the plant's refrigeration system to ensure it meets new environmental legislation entering force in January next year.Costain Chief Executive Andrew Wyllie said: "We continue to expand our capabilities in complex design and procurement in the oil & gas sector."Shares in Costain fell 1p to 264p at 08:41 in London.PW