May 04, 2020

Hydrodynamic Separators Aid in Transportation Infrastructure Project

Two Contech hydrodynamic separators were used in this infrastructure project in New York when engineers needed a treatment solution to treat 15.42 acres of impervious area.
Two Contech hydrodynamic separators were used in this infrastructure project in New York when engineers needed a treatment solution to treat 15.42 acres of impervious area.

The East Side Access mega project is one of the largest transportation infrastructure projects currently underway in the United States. The project provides new Long Island Rail service to the east side of Manhattan, supplementing existing service to Penn Station on Manhattan’s west side and Atlantic Terminal in Brooklyn. 

The $11.1 billion project encompasses work in multiple locations in Manhattan, Queens, and the Bronx and includes more than 8 miles of tunneling. When completed, East Side Access will serve approximately 162,000 customers a day, providing a faster and easier commute from Long Island and Queens to the east side of Manhattan in a new 8-track terminal and concourse below Grand Central Terminal. 

Engineers needed a treatment solution to treat 15.42 acres of impervious area in a section of the project in Long Island City, NY.  The New York State Department of Environmental Conservation (NYSDEC) requires treatment for 100% water quality flow treatment from the 90th percentile storm event, and any treatment system must also be approved by the NYSDEC.

The site had many challenges, such as large flow rates of 9.45 cfs, high groundwater, heavy loads, proximity to rail lines, and elevation and utility constraints. Therefore, the engineer was forced to look at alternate solutions to the standard land based treatment practices approved by the NYSDEC. The Vortechs hydrodynamic separator was the only treatment systems capable of meeting all of these needs. 

Contech worked directly with the engineer to provide calculations for the water quality flow that needed to be met, as well as the structural designs to account for the AREMA E-80 surcharge.  Contech also coordinated with the MTACC East Side Access Package Manager who required the unit be waterproofed as to not present any issues with approvals. 

Two Vortechs systems were specially designed by Contech Stormwater Engineers.  The units were very wide (13’-8” wide x 19’-8” long) and heavy (heaviest pick weight was 111,500 lbs).  The depth of the structures also required extra risers to allow for access for cleanout at the surface. The units were also treated with a coal-tar epoxy coating on all outside serfaces to meet the waterproof requirements. 

Delivery and installation was challenging due to the urban location of the project in Long Island City, NY. Contech coordinated the delivery trucks to be onsite early in the morning, as the side streets available for access to the site had to be closed off to commuters looking for parking.  The site was very tight as well and required a high degree of skill by the driver to maneuver into site in reverse.

The installation was a success. With the use of a large crane, the units were picked from the truck and immediately installed. This allowed the contractor to backfill the area quickly with little disturbance to the workflow on site.

 

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