PORTLAND — The Casco Bay Ferry Lines board has given final approval to a $3 million renovation project on Portland’s waterfront. The project will double the size of the terminal and upgrade the pier where five ferries dock.

Ferry officials say they are responding to heavy demand. General Manager Hank Berg told WCSH-TV that long lines form for the ferries in the summer.

The terminal was built 25 years ago to handle about half a million passengers per year, and now handles twice that number. The project will include a new, expanded waiting room.

The project will be funded with a federal grant so there will be no ticket price increases. The terminal will remain open during the renovations.