This article originally appeared in Storm Water Solutions March/April 2020 issue as "Smart Solutions"
Referred to as Mile Square City, the densely populated metropolis of Hoboken has a history of flooding because of its low-lying location on the New Jersey side of the Hudson River. Since purchasing and taking control of the sewer lines within the city in 1998, the North Hudson Sewerage Authority (NHSA) has worked diligently to upgrade and modernize Hoboken’s combined sewer collection system with a storm water pumping station.
“It’s not as bad as it used to be, but 75% of Hoboken is in the 100-year flood plain, and I would say about 20% of it is at or below mean high tide,” said Fred Pocci, authority engineer, NHSA. “When we took over operation of the sewer system in 1989, every time it rained the streets flooded. We looked at the elevation, and said we have to pump this water out of here.”
As part of the city’s comprehensive flood resiliency plan to protect Hoboken from all types of flooding, NHSA installed the city’s first wet weather pumping station in 2011 to alleviate flooding in the southwest portion of Hoboken. The H1 pumping station on Observer Highway is tasked with maintaining and reducing street flooding as well as discharging combined sewer overflows. The pumps are activated automatically when the water in the sewer system reaches a certain level, and excess water is pumped into the Hudson River.
Flood-Prone Northwest Region
While the H1 pumping station provided southwest Hoboken relief from chronic flooding, the city’s northwest region remained vulnerable—with even a passing steady rain routinely washing out cars, homes and businesses.
To resolve the ongoing issue, the NHSA partnered with the municipality to install a second wet weather pumping station to help the area stay above water during major storms.
“The next thing we tackled was the very low spot in central Hoboken around Madison and Ninth Street,” Pocci said. “Mid-Hoboken drains through 11th Street so we built it completely underground: controls, pump station, everything because it’s in the flood zone.”
The H5 pumping station, completed in 2016 at a cost of $9.5 million to the city and $1.5 million to the sewerage authority, is intended to help protect a low-lying area of western Hoboken that had been susceptible to flooding after heavy rains and remained under water for days following storm surge from Hurricane Sandy.
Since it went online, H5, which is built entirely underground, has provided relief from chronic flooding in the northwest section of the city, particularly benefiting the hard hit area between 9th and 13th Streets.
Smart pumps and controls from Xylem’s Flygt brand contributed to the pump station design that helped Hoboken reduce costs, increase efficiencies and alleviate storm water flooding for the city on the Hudson River. The storm water pump station features two high-performance submersible pumps. The pumps each have a capacity of discharging 40 million gallons per day for a total pumping capacity of 80 mgd.
“The efficient Flygt propeller pump with its submersible motor is ideal for storm water pumping,” said John Corkery, municipal sales manager, PSI, a Xylem representative in Middlesex, New Jersey.
Flygt propeller pumps are designed to transport large volumes of water at low heads. The slim profile of these pumps provides a considerably smaller pump station footprint than that of non-submersible pumps. Flygt submersible propeller pumps operate directly in the pumped liquid and are easily installed and removed from the pump station. No fastening bolts are required. Because the pumps operate in and are submerged in the pumped liquid, they are easy to install and the motors run cooler and more quietly than those of non-submersible propeller pumps. In addition, the pumps incorporate Flygt N-technology, known for its self-cleaning capabilities and sustained high efficiency.
The slim profiles of the pumps provided another benefit. With limited space for the wet weather pumping station in the densely populated city, the pumps’ slender design facilitated installation in the extremely tight quarters of the underground facility.
Little of the H5 pumping station is visible above ground other than a pair of generators and a curved green pipe that stand on a roadway divider down the center of 11th Street west of Hudson Street.
“H5 is situated in a high-end residential community,” said Phil Reeve, facility operator, NHSA. “Top on their list was they didn’t want to see anything after it was done, so the whole control building for the pump station is below grade, and its entrance is in the middle of a center median with plantings all around it. You could drive by it a 100 times and never even see it.”
Once the H5 pumping station was operational, NHSA commissioned a report to see how well the pump was doing to prevent flooding in the city’s northwest region.
“We needed a way to assess how effective the pump was at keeping the streets from flooding,” said Don Conger, facility operator, NHSA.
Flow sensors were installed throughout the system, and data was collected and analyzed over a six-month period. During that time frame, the monitoring system identified 36 storm events where the pumps were activated.
“During those six months, we had enough rain on the street where it would have flooded the city out, but we only saw some flooding in four of those events where otherwise it would have been 36,” Conger said. “The results were very clear that the pump station was doing its job and keeping the water off the streets.”
The report concluded that the H5 pump kept city streets and basements free of an unhealthy mix of sewage and storm water runoff that otherwise would have overwhelmed the NHSA’s combined sewer system.
“One of the unique things about the control system is there’s actually surge predictor programming built into the station, so not only do we monitor the flows and operate the pumps, but we look at it on a time base and try to stay ahead of a flood event,” said Bryce Parkhurst, senior manager, PSI.
Today, the H5 and H1 pumping stations are working together to alleviate flooding woes and help keep Hoboken’s low-lying, west side dry through heavy rains and high tides that previously would have inundated neighborhoods in the area.