Alcatraz Island has not held inmates since 1963, but marine construction support to keep the island operational as a popular tourist destination continues. It is being performed by Ballard Marine Construction in conjunction with COWI consulting group. A key component of this operation was to not interrupt the daily operations of Hornblower Cruises & Events who transport over one million tourists each year.
Initial work involved developing and executing a pile repair to an existing 30-inch diameter steel piling. The rehabilitation of the pile included installation of rebar reinforcement and 30 feet of tremie poured grout material. This first step was necessary to facilitate a related barge swap that would put a temporary personnel loading platform in place while the permanent barge was being serviced. To rotate the barges a temporary barge was mobilized to the site in order to relocate the gangway that connects to the adjacent deck. With the temporary barge in place, the M/V Solitary, a support vessel that services the Hornblower fleet, assisted in moving the permanent barge to a offsite graving dock.
Upon repairs of the permanent barge, the rotation of the temporary barge being replaced with the now repaired loading barge will be completed. In order to support the goal of zero operational interference to the Hornblower operations, all construction activity occurred between 10PM and 7AM each day.