Long Distance Concrete Pumping Record Set Putzmeister Units in New York City’s First, Street-level Tunnel Pour
Long Distance Concrete Pumping Record Set Putzmeister Units in New York City’s First, Street-level Tunnel PourSTURTEVANT, Wis. (Oct. 20, 2003) – A new long distance concrete pumping record for New York City was established during construction of a horizontal steam tunnel that stretches 16 blocks beneath the streets of Manhattan. Concrete was pumped as far as 4,100 feet in the project, which is wrapping up this fall.
A standard Putzmeister BSA 14000 trailer-mounted pump was in action every other day during the majority of the pour, which was completed in less than 90 days. Construction began in November 2001.
The $42.3 million undertaking involved building a tunnel 12 feet, 7 inches in diameter to connect two of Consolidated Edison’s steam-generation plants. Consolidated Edison operates the world’s largest steam-supply system, serving more than 100,000 homes and businesses. The steam is used to heat buildings and water and for air conditioning.
Alexander Wagner Co. of Paterson, N.J., rented the Putzmeister equipment that was placed in action by Schiavone Construction Co., the project general contractor from Secaucus, N.J.
Along with setting the record for the longest concrete pour in New York City,
the project marked the first tunnel constructed in the city by pumping concrete from the surface. Previously, a drop-shaft process was used whereby crews drill shafts about 1,000 feet apart, drop a concrete-delivery pipe through the shafts, allow concrete to free fall in the pipe, remix the concrete, then pump it into forms with an electric-powered trailer pump positioned inside a tunnel.
On the steam tunnel, the Putzmeister BSA 14000 remained at street level on First Avenue on the island of Manhattan, between 20th and 36th Streets, to pump 4,800 yards of concrete through a 5-inch pipeline into forms below. In total, about 10,000 yards of concrete will be used on the project.
The drop shaft method of pouring is a relatively slow process, yielding 30 yards output an hour on average. When concrete was available on the steam tunnel job (outputs varied because of the availability of concrete being delivered) the Putzmeister BSA 1400 typically placed in excess of 95 yards an hour. At one point, however, the unit was clocked pumping up to 114 yards an hour. For comparison purposes, the pump’s maximum output is rated at 134 yards an hour.
“As a result of pumping from the surface, the daily quantities were three times greater than could have been attained with a drop shaft and it took less than half of the required time,” said Alex Wagner, co-owner of Alexander Wagner Co. “As a result, Schiavone Construction became convinced that this is the only efficient way to construct a tunnel.”
Also on site was the smaller Putzmeister BSA 2109 trailer pump, used as both
a backup and as a convenient way to wash out the concrete delivery pipeline. Typically, about 20 yards of concrete remained in the line when pumping ended for the day. The BSA 2109 was used to flush water through most of the line. Then the pump would be shut off before the water reached the forms. The line subsequently was disconnected and the wash-out process completed.
A lack of ready-mix plants in Manhattan was one of the major concerns that project planners faced. This meant concrete had to be delivered from the Brooklyn borough, via mixer trucks crossing over the Manhattan Bridge. Traffic congestion, accidents and even terrorist threats could mean long delays. And if the supply of ready-mix was interrupted during a pour, concrete could be stuck in the delivery pipeline. Potentially, more than 4,000 feet of pipe could be lost.
To overcome such challenges and the heat of summer, pouring crews tried to keep two mixer trucks on-site at all times, vary output to keep concrete flowing and use a three-hour retarder in the mix. In addition, the general contractor committed to only 160 yards of concrete a day over concern about the availability of materials.
Unfortunately, all of the anticipated concerns occurred during construction
of the tunnel – traffic tie-ups, accidents, terrorist threats and even a jumper
off the Manhattan Bridge. Fortunately, those events occurred on days when pumping was not scheduled and the ready-mix company, Empire Concrete
of Brooklyn, supplied a Super Plasticizer concrete mix with a special 3/8-inch
stone without fail.
“At first, only half of the tunnel was going to be pumped from one end. However, when everyone saw how successfully the first 2,000 feet was handled, it was decided to continue on and pump the second half of the tunnel from the same setup and with the same Putzmeister 14000 trailer pump,” Wagner said.
A Putzmeister 55-Meter, truck-mounted boom pump is helping finish up the job by pumping concrete through a shaft at one end of the tunnel. The 35-foot-wide, 112-foot-deep shaft is an exit hole which will provide a route to the surface for the tunnel boring machine and other equipment.
Planners have allowed for future extension of the tunnel.
Owner: Consolidated Edison – New York City
General contractor: Schiavone Construction Co. – Secaucus, N.J.
Pumping contractor: Alexander Wagner Company, Inc. – Paterson, N.J.
Ready-mix supplier: Empire Concrete – Brooklyn, N.Y.
Equipment: Putzmeister BSA 14000 trailer pump and BSA 2109 trailer pump; 55-Meter concrete boom pump