Dredging for Beneficial Reuse and Improved Navigation

The Port of Long Beach (Port) is in the process of implementing a multifaceted capital improvement program that will culminate in the redevelopment of the existing Pier E Terminal. This program, known as the Middle Harbor Terminal (MHT) Redevelopment Program, includes filling an existing slip with beneficially reused dredged material from various borrow sites located within the Port, including the West Basin. This paper will focus on the multiple benefits resulting from selecting the West Basin borrow site to serve as a fill source for the MHT fill site. Pier T is currently the largest terminal within the Port, with 385 acres for cargo handling. Access to Pier T is through the West Basin approach channel, which currently has a depth of -50 feet, which is adequate for most vessels calling on Pier T. However, the larger container ships with deeper draft depths that are closer to the current depth present a challenge for Harbor Pilots. To improve navigation safety for vessels with deeper draft depths, the West Basin requires additional depth. The development of the MHT program presented an opportunity for the Port to address multiple needs under a single contract. The plan to strategically borrow material from the West Basin will help facilitate navigation for those container vessels with deeper draft depths, to call at Pier T. Using a forward thinking planning approach that allowed the West Basin to be a borrow site for the MHT fill site, the Port will be able to complete the next phase of the new expanded MHT terminal, while obtaining additional depth in the West Basin allowing for improved navigation safety for the vessels that call on Pier T. A key element for success was coordination among the various design teams to ensure that the dredged material used to fill the slip was properly managed. Dredge material from the West Basin (Over 1.6 million yards) had varying geotechnical properties as well as chemical characterization, which had to be managed properly to ensure placement promoted constructability and met environmental restrictions. Dredging involved using both mechanical and hydraulic pumping methods. Material planned for use as rock dike foundations was restricted to mechanical dredging to promote better stability. There were also stringent environmental mitigation requirements for the dredging operations in order to mitigate environmental impacts.