A Port of Tacoma contractor will begin to drive the first of 361 concrete pilings today in the Blair Waterway to expand a Washington United Terminals wharf. The $31 million project will extend an existing berth another 600 feet to support two large new cranes the Hyundai Merchant Marine-owned terminal added in January 2009. The larger wharf and “super post-Panamax” cranes will be able to serve the world’s largest ships. Manson Construction of Seattle plans to work from about 7 a.m. to 7 p.m. weekdays and possibly some weekends to drive 29 piles for the berth before the annual fish migration season begins mid-February, ending all in-water work until mid-July. The extended berth should be complete by July 2011, ready to serve the world’s largest ships.