New York City Transit plans to issue formal bid documents the week of June 10 for major reconstruction work on two subway tunnels that Superstorm Sandy heavily damaged. Prime contractors are expected to be selected in July with work set to start later this summer, the agency says.

Both tunnels—the 5,000-ft-long Montague and the 1,200-ft-long Greenpoint tubes—sustained ceiling-high floodwaters that "corroded, degraded or ruined almost everything from tracks and switches, to signals and controls, to power and communications cables," the agency said in a June 5 statement.

The storm flooded nine of the agency's 14 under water tubes to various levels but the Montague tube, the longest of the 14, and the Greenpoint tube, one of the shortest, suffered the worst damage, says Joseph Leader, NYC Transit acting senior vice president. The Montague tube, which carries the R train under the East River between Brooklyn and Manhattan, sat in corrosive salt water for 10 days and is in far worse condition than Greenpoint. The result is that work on this tube falls "just short of completely rebuilding the tunnel," he adds.

Each tunnel will be a separate project and each project will likely have multiple contracts, with some contracts likely to be design-build, Leader says. The Montague project requires shutdown of the R train service starting the first week of August and is expected to be completed in 14 months. The agency plans to use outside contractors for most of the Montague work, Leader says.

The Metropolitan Transportation Authority (MTA) NYC Transit's RFQ for Montague work estimates the project's total at more than $100 million, which will be funded via the Federal Transit Administration.

Work this year on the Greenpoint tube, which runs under Newtown Creek between Brooklyn and Queens, will require G train service shutdown for 12 weekends starting July 6. In 2014, the agency will reassess what remains to be done and whether it will keep the same work schedule for this project, Leader says. The agency’s in-house crews will perform most of this project, except for some signal, pump room and system hardening work, he adds.

While temporary repairs have already been made to return subway service to these tunnels, they are not enough for the long term, Leader says. Another MTA official echoed that point earlier this year at an ENR New York MTA conference.

"What we see as the real Achilles [of the Montague project] are the duct banks on both sides," Leader says, adding that Greenpoint's duct banks are in relatively good condition. However, Montague's banks, which carry electrical and communication lines as well as other critical components, are so severely damaged that they need to be "completely chipped and rebuilt," he adds.

Such chipping operations in under river tubes are usually performed using jackhammers. "You don't want to go in with large pneumatic pieces of equipment" for fear of puncturing the lining of the tubes, Leader says. However, the jackhammer process of chipping out the duct bank, coupled with loading and removing what is expected to be tons of debris from the operation, "will take some time," Leader says.

Also, "one of the toughest things about a job like this is that you are not looking at one asset that was damaged; you're looking at multiple assets, so staging and sequencing the work itself is difficult," he adds. "It's a huge feat to try to get something like this done." Even the shorter Greenpoint tube will require coordinating multiple trade disciplines to work in only a 1,200-ft area, he adds.