With the first work season completed by subcontractors Granite Construction and Condon-Johnson & Associates, Project Manager Drew Paup and the project team at Manson’s North Extension Stabilization Step 1 (NES-1) design-build project in Anchorage, AK, are gearing up for Season 2.
A high priority for the Municipality of Anchorage, which owns and operates the Port of Alaska (the Port), the NES-1 project is part of the Port’s 10-year Modernization Program, which aims to replace the aging marine structures and related infrastructure to support commercial and military vessels that serve and protect the state of Alaska. A critical transportation resource, the Port is the primary inbound cargo-handling facility in the state. The Manson project team will stabilize a vital section of the Port’s North Extension with ground improvements, removal of an existing sheet pile wall, excavation, placement of rock, and dredging more than a million cubic yards (CY) of material to realign the shoreline.
“Anchorage experiences extreme seismic activity, and it is important for the Port to improve its infrastructure and achieve resiliency against the effects of earthquakes,” Drew explains. “Manson’s NES-1 project serves the people of Alaska, as 90 percent of the state’s residents rely on the Port as a vital transportation gateway in Anchorage.”
Preseason Efforts
Manson partnered with design firm WSP, Condon-Johnson, and Granite early to establish a cohesive project plan, exclusive partnership, and the collective mindset supporting the project’s success. The strength of the group comes from their shared long-standing history of performing infrastructure solutions in Alaska.
“Being involved early during the proposal phase allowed Manson, Condon-Johnson, and Granite to address concerns and find solutions for the project,” says Soheil Kamalzare, Condon-Johnson Project Manager. “The experience from all sides made the project more visible and the partnership much stronger.”
Granite and Condon-Johnson Take the Stage
In January 2023, Granite deployed its project staff and crews to remove snow and to take soil samples at NES-1, according to Kelly French, Granite Project Manager.
“With Granite being the local company, Manson and Condon-Johnson understood the importance of this project and how it will benefit the entire state of Alaska,” Kelly explains. “Granite did a lot of logistical and prep work during the early phases of the project. After a few months finalizing sequencing and planning, we fully mobilized to NES-1 with Manson and Condon-Johnson in April 2023.”
With the Port’s operations in full swing, Granite and Condon-Johnson began earthwork and ground improvement work simultaneously at the North Extension location, with Drew and the Manson project team on-site to oversee and support both subcontractors.
Granite initiated land-based excavation of approximately 40,000 CY of material at the North Extension. The work supported Condon-Johnson’s ground improvement phase, building a bench—a trough-like area—for Condon-Johnson to work with, and providing management of spoils and material disposal. In addition to the excavation work, Granite began hauling and stockpiling filter and armor rock to the Port. Granite crews have been rock blasting and storing the boulders and rocks for slope protection for next season at NES-1, and this work will continue in 2024 after winter passes.
“Granite owns local quarries in Alaska that will provide the necessary materials to prepare for Season 2,” Drew says. “Their preparation efforts will allow the Manson team immediate access to large quantities of rock, mitigating potential delays for next year.”
A Solid Ground
As Granite completed the excavation, Condon-Johnson began ground improvement work to stabilize 1,400 linear feet (LF) of the inland section of the North Extension that will stabilize the future shoreline during seismic events. Usingseveral high-powered drill rigs with augers, the Condon- Johnson team used a Deep Soil Mixing (DSM) technique to blend soil and cement which will strengthen the ground up to 52-ft. below the surface. The team performed DSM on 946 columns in the site area, with approximately half of the mixed portion of the columns requiring an alternative method due to natural obstructions.
“The Condon-Johnson team went down with a drill rig and a 6-foot auger attached to mix the materials,” Soheil explains. “They encountered boulders while installing the DSM method and stopped work until a solution was provided.” The design-build team collaborated with the Port to work concerns, which led to the alternative installation method of jet grouting—injection of mixed material at high pressures—to complete the ground improvement work. “Manson and Granite’s support created a comfortable environment for us to bring solutions to the table,” Soheil says. “It allowed Condon-Johnson Superintendents Guy Donaldson and Ray Exum to adapt and direct their team to move forward with the jet grouting method, allowing us to finish on time and complete the work for Season 1.”
Season 2 Preview
With the design, excavation, and ground improvement work complete, Drew and the Manson project team are shifting their focus to Season 2 which begins in the Spring of 2024. The upcoming work will involve several self-performed scopes, including the dredging of approximately 1.2 million CY of material, demolition of 6,200 LF of an existing sheet pile bulkhead structure, and the placement of armor and filter rock.
“I’m looking forward to having all our equipment mobilized and on-site in April 2024,” Drew says. “The planning efforts that go into making that happen will be significant. Once on-site, we can focus on what Manson does best: marine construction and dredging.”
