DOT Discusses Dewatering For New Kosciuszko Bridge
The end-of-the-month meeting concerning construction of the new Kosciuszko Bridge was focused on dewatering as a primary step toward building the part of the bridge that will span Newtown Creek. The meeting was held at the New York state Department of Transportation (DOT) Region No. 2 office at the Hunters Point Plaza building, 47-40 21st Street.
Dewatering is the method of establishing, at least temporarily, a work space in an area previously under water. The new bridge is to be constructed south of the old one and will be built on a less steep grade, necessitating the sinking of a dozen footings for the bridge’s foundational structure. Those that go below the water surface can be built only after dewatering.
The dewatering process means the displacement of highly contaminated fluids in Newtown Creek that must be tightly managed to avoid the release of toxins. At this latest meeting, engineers explained the need for DOT to get a state pollutant discharge elimination system (SPEDES) permit from the state Department of Environmental Conservation (DEC), for construction site dewatering.
DEC approves so far, saying it “has made a tentative determination to approve this application for a new permit for a proposed temporary discharge of up to 65,000 gallons per day of treated groundwater into Newtown Creek...from a treatment system at the applicant’s construction site located in Brooklyn and Queens where the applicant is replacing the Kosciuszko Bridge. Construction dewatering is required to facilitate construction of bridge piers and stormwater collection infrastructure. Three outfalls and two contemporary construction platforms will also be constructed.”
The meeting was opened by Robert Adams, project manager from the state DOT, who promptly introduced Michael Abrahams, project manager from the construction company, Parsons Brinkerhoff. Abrahams said the plan was to build the new bridge while the old one is still being used, then demolish the latter. The main adjustment in the adjacent neighborhoods would be the realignment of Cherry Street on the Brooklyn side, with a retaining wall to be built there additionally. The project is now part of Governor Andrew Cuomo’s New York Works program. Construction is due to begin this fall and be finished (everyone hopes) in 2020.
Richard Hart of EPM followed, saying that the contaminant metals found through examination of the water were lead, arsenic, mercury, chromium and selenium. He called petroleum a lesser problem on this particular project. The danger of PCE (perchloroethylene) presence is not a major one in parts per billion, he said, but the matter would be treated with utmost seriousness. Ion exchange, used to soften water and purify industrial chemicals, would be employed if necessary.
At question time, someone asked if the dewatering process would cause foul odors. Hart said there is no odor to speak of in these metals, and it couldn’t begin to match the bad odors that arise from the water in the creek already. Another person asked about a means to catch runoff from the roadway of the new bridge, and Abrahams said a drainage pipe would be part of the bridge, having a cleaning process within it.
He said also that acid soil would not be the problem now that it was for the bridge builders in the 1930s. At that time, the builders of the first bridge had to coat footings with tar to keep acids in the soil from attacking them.
Acid soil is not so apparent now, he said, perhaps lessened by constant percolation and runoff over the years. Another inquirer asked if, as she had heard, some of the footings would penetrate the cap that was put over the highly toxic Phelps Dodge site, on the Queens side. Abrahams said that would be necessary, and great care would be exercised in the task. He said that one industrial advantage at the project’s disposal is the Long Island Rail Road, which runs along that same Queens side and could be used for taking away rubble.
Among the extra-industrial considerations were Indian artifacts, the stone monuments in nearby Old Calvary Cemetery and the demand for a park on the land under the bridge. Abrahams said that any Native American artifacts that happen to be discovered would be dealt with in coordination with New York state Historical Preservation, though he added that so many levels of ground have been altered there that he doesn’t expect any to be discovered. He said the builders of the new bridge have also taken into consideration the possible effect of vibration from the project on the Calvary monuments and will labor not to damage them. The park project has not been forgotten either, Abrahams said; the builders are in contact with the state Department of Parks and Recreation concerning its eventual construction.