Innovative Reuse of Drydocks as Contained Disposal Sites

When the Port of Long Beach decided to redevelop the Long Beach Naval Shipyard into a modern container terminal, significant challenges were expected. The project involved compelling design challenges to incorporate existing physical features into a workable container terminal. A major challenge that came late in the Pier T Container Terminal Development was the reuse of the three existing concrete drydocks. Due to the significant size of these drydocks, the demolition and removal of the drydocks would have been prohibitively costly. Working closely with the design team, the Port decided to abandon the drydocks in place and use them as contained disposal sites for bay sediments deemed chemically unsuitable for ocean disposal. This approach provided major cost savings for demolition and also provided a confined disposal site for over 600,000 cubic yards of unsuitable dredge material. The solution was in alignment with the guiding principles and fundamental goals of the Port of Long Beach's Healthy Harbor Program, which was further developed into their groundbreaking Green Port Policy. This paper will discuss specific challenges to prepare the drydocks, methodology employed to bridge and cap geotechnically poor dredge material, and provide a pavement section suitable for the heavy demands of a container yard. The primary issues to be reviewed include: (1) Design and construction of concrete counterfort retaining walls to seal off the ends of each drydock and support the wharf structure to be built across them. (2) Filling the third drydock, which was nearly twice the size of the first two, with the most geotechnically poor material resulted in increased difficulty with capping and surcharging of the dredge material. (3) Design considerations employed to develop the container yard over the drydocks, including the innovative use of geosynthetics to develop a suitable pavement section over the dredge material. (4) How the design team and constructor worked together to overcome challenges encountered while working over the filled drydocks.