When it made landfall just north of Atlantic City, New Jersey, on Monday, October 29, 2012, Hurricane Sandy extended 450 miles (750km) out from the centre. The ensuing storm surge impacted hundreds of miles of densely populated coastline. While hurricanes are categorised by peak wind speed, storm surge potential is correlated to a storm’s integrated kinetic energy (IKE) rating, a measure of the wind speed across the ocean area over which the winds blow. Sandy’s IKE rating was the second highest in modern history, only surpassed by Hurricane Isabel in 2003.
For New York City’s subway system, this was the most devastating storm in its 108-year history. When water from the 13ft (4m) storm surge flooded into Lower Manhattan, eight of the 11 tunnels under the East River, plus a ninth subway tunnel under Newtown Creek, were inundated, crippling the city’s transportation network. The New York City Metropolitan Transit Authority (NYCMTA) operates some 300 pump rooms, running on electricity, to deal with the 13-15 million gallons (49-58 million litres) of water infiltration expected throughout the subway system and vehicular tunnels on a daily basis. However, the entire subway electrical system had been shut down ahead of Sandy as a safety measure. The MTA’s three diesel-driven pumping trains were brought into service, but additional private sector dewatering crews, together with the Fire Department of New York (FDNY) and the military, were critical to speeding up the drying out and repair processes.
Rapid Response
Geotechnical contractor and dewatering expert Moretrench received the first calls around 4am on Tuesday, October 30 from MTA Bridges and Tunnels and the NYC Department of Environmental Protection. Shortly thereafter, calls began to come in from a number of private clients. While Moretrench has considerable in-house resources at its Rockaway, New Jersey, headquarters, more pumps were needed to respond to all the requests for immediate assistance. Twenty, 15-HP submersible contractor pumps, which can tolerate some fines and can provide over 100ft (30m) of lift, were immediately ordered from a Connecticut supplier and delivered overnight to the company’s Yonkers premises, enabling Moretrench to mobilise to multiple locations simultaneously.
Moretrench is no stranger to emergency pumping in New York City, having been heavily involved in the pumping and dewatering effort in the immediate aftermath of the 2001 attack on the World Trade Center. As was the case then, time now was of the essence. Within hours of the first phone call, crews had mobilised and a substantial pumping effort was underway at several wastewater treatment plants and pump stations for the NYCDEP. The greatest challenge, however, was to pump out two major transportation links, the Brooklyn Battery Tunnel and the Port Authority Trans-Hudson (PATH) tube at Exchange Place in Jersey City, New Jersey.
Brooklyn Battery Tunnel
The Brooklyn Battery Tunnel, officially renamed the Hugh L. Carey Tunnel (HLCT) in 2012, runs under the East River connecting the southern tip of Manhattan with the Brooklyn- Queens (Gowanus) Expressway (I-278) in Brooklyn. At its midpoint, the HLCT brushes the north east side of Governors Island, which sits in the Upper New York Bay at the mouth of the East River. At 1.7 miles (2.8km) in length, it is the nation’s longest continuous underwater vehicular tunnel and comes under the direct auspices of the MTA Bridges and Tunnels, a division of the MTA.
Since the tunnel was constructed in 1950, the water levels in the bay have risen 9in (23cm), putting the already low-lying tunnel portals below sea level. The storm surge, driven by Hurricane Sandy, a nor’easter, and a full moon coinciding with high tide at the New York Harbor, had a height cresting at 13.88ft (4.23m) in Battery Park in Lower Manhattan. This storm surge was unprecedented and was more than 3ft (0.9m) above the previous record set in 1960. It exceeded FEMA’s rating for a 500-year storm surge and completely overwhelmed the tunnel drainage system, resulting in an estimated 60 million gallons (227 ML) of flood water pouring into each of the 31ft (9.45m) diameter twin tubes, completely filling the central two-thirds.
Moretrench met with MTA commercial contractor Restani on October 30 to determine the course of action, and by the following day had mobilised to the Brooklyn portal. Some 1,700ft (520m) of 6in (150mm) diameter hose and piping was laid from the tunnel entrances to reach the floodwater, and the first of five 40- HP turbine submersible pumps, each capable of handling 1,000gpm (3,785 litres per minute) at peak performance, together with a generator and fuel tank, were loaded onto a flatbed trailer and backed in. Four more 40hp pumps and a second generator were similarly set up and operational by Thursday, November 1. Water removed from the tubes was pumped into a sump located at the Brooklyn portal permanent pumping room, which was running on emergency power and operated by MTA Bridges and Tunnels, and from there discharged into the sewer system. With a Moretrench technician maintained on site, Local 15 Operating Engineers then took over responsibility for keeping the pumps going around the clock.
A major pumping effort was concurrently underway via the large tunnel vent shaft building situated on the tip of Governors Island. At approximately 150ft (45m) below the surface, the tunnels here are at their lowest point. On Friday, November 2, six 40hp turbine submersible pumps, three 15hp pumps, two generators and associated piping were loaded onto a barge and shipped to Governors Island. Moretrench set up four of the 40hp pumps in the East Tube and two in the West Tube. To accomplish this, the crew worked within the access ports of the vent shaft airways, cutting through the steel plate damper doors and connecting the 10ft (3m) sections of piping necessitated by the restricted space. As the water level in the tunnel dropped, one of the 15hp pumps was set up in the ejector pit under the pump room between the two tunnels, which was designed to cater to rain events. Two 15hp pumps were left for sumping operations during tunnel clean up and repair after Moretrench demobilised on December 8.
Exchange Place
The PATH tube at Exchange Place in Jersey City, New Jersey, provides direct access to Lower Manhattan, with connections to the New York City subway system and the World Trade Center. During the flooding, more than 12ft (3.7m) of water filled the underground station, with tens of millions of gallons flowing into the century-old, cast-iron tubes that run under the Hudson River.
On Saturday, November 3, Moretrench met with the Port Authority of New York and New Jersey and Ferreira Construction, which was directing operations for the Port Authority. Moretrench provided and set up lighting in both tubes, together with large ventilating fans to dissipate exhaust fumes, then mechanically pushed in two 30hp submersible turbine pumps, hosing, and generators all loaded on to a utility cart, and began dewatering the north tunnel. Meanwhile, the FDNY were setting up a train-mounted, 6in (150mm) hydraulic pump to dewater the south tunnel. Pumped water from both tunnels was piped to a sump set up in a utility room in the main station area where the US Army Corps of Engineers operated a 12in (300mm) diameter pump to discharge the water back into the East River. When the Corps obtained an additional large pump and was then better equipped to take over the north tunnel dewatering, Moretrench shut off the two 30hp pumps and focused on maintaining lighting and ventilation. The site was demobilised on November 11.
World Trade Center
Following the attack on the World Trade Center, Moretrench has worked extensively on the WTC rebuilding effort, completing more than 25 contracts between 2001 and 2012, including dewatering for foundation installation for Towers Two, Three and Four, The Freedom Tower and the Memorial site.
At 6am on Wednesday, October 31, Moretrench met with Bovis Lend Lease, construction manager for the World Trade Center Memorial and Museum, and by 5am on November 1 had mobilised to the memorial site and begun setting up a 75hp submersible pump in an elevator shaft. A second 75-HP pump was up and running in the museum building by Friday, November 2 and two 15hp pumps were operating at the bottom of a stairwell. By Monday, November 5, the site had been largely pumped out except for localised areas. The large pumps were shut off and three additional 15hp contractor pumps were added, along with four, 2in (50mm) pumps, to handle the remaining water. Pumping continued until the maintenance pumps came back into service on November 28. Moretrench also supplied six pumps to Tishman Construction to handle flood water at Towers Three and Four.
All in all, Moretrench personnel pumped at 20 separate sites, moving in excess of 250 million gallons (946 million litres) of water. Including equipment supplied for additional sites and operated by others, the company mobilised more than 50 pumps in various sizes, thousands of feet of hose and piping, and 12 generators in just three days. "It was a monumental logistical exercise as well as work effort," says Moretrench general superintendent Ryan Barrella. "We worked around the clock, as did agencies and other private contractors involved.
