The commission in charge of the sweeping Gateway Project to put new rail lines under the Hudson River awarded a crucial contract Friday to shore up the riverbed.
The Gateway Development Commission voted unanimously to award the first $100 million of an expected $284 million contract to Weeks Marine to begin work shoring up the silty riverbed ahead of tunnel boring operations.
Beginning late this year, work crews will inject a mixture of concrete, soil and water into a shallow portion of the riverbed along the Manhattan side.
The silt in that portion of the riverbed is too soft to support digging, GDC officials said. The infusion of thicker materials and concrete is intended to strengthen the riverbed above the future tunnel.
Crews will begin working at the Manhattan shoreline, then work westward toward the Hudson’s navigable channel.
Known as the Hudson River Ground Stabilization project, the work is a necessary step before boring can begin.
“The end product is a block of reinforced earth in the riverbed 1,200 feet long by 110 feet wide,” Jim Morrison, the commission’s chief technical officer, said.
In order to get that block in place, Morrison said, crews will build a temporary cofferdam to isolate and protect the rest of the river from the sections being reinforced. Boat traffic on the river should be unaffected.
The first phase of work will consist of design and testing of a cofferdam system. Phase 2, which is expected to begin in the fall, will involve the actual reinforcement work. Crews are scheduled to complete that work in 2027.
Friday’s award constitutes a total of $1 billion in construction spending already in the ground on the Gateway project, GDC CEO Kris Kolluri said.
The total Gateway Project, which also includes the restoration of the existing North River tunnels built in 1910, the replacement of several rail bridges across the Meadowlands, and a link under Jersey City and Hoboken to the Hudson River tubes, and a southward expansion of Penn Station is estimated to cost at least $40 billion.
The Hudson Tunnel work alone is estimated to cost more than $16 billion.
Work has already begun on two portions of the project.
Construction on the concrete casing for the tunnel’s Manhattan landing began in the fall, a $692 million project.
Crews have also begun work allowing for a rail right-of-way under Tonnelle Ave. in North Bergen, N.J.
