The New York City Water Supply System provides one billion gallons of safe drinking water to New York City’s 8.5 million residents every day. The system also provides about 110 million gallons a day to one million people living in Westchester, Putnam, Orange, and Ulster counties. Neighborhoods in New York City receive their drinking water from reservoirs of the Croton System, Catskill System and Delaware System, or often a combination of all three.

The project
With its millions of residents and visitors, New York City requires a tremendous amount of clean water every day. More than half of New York’s drinking water is conveyed to the city via the Rondout-West Branch Tunnel of the Delaware Aqueduct. This is a 13′ diameter 44 miles-long tunnel constructed in 1944, supplying up to 1,306 cubic feet of drinking water per second via a natural incline.

The challenge
As a result of geological conditions, the tunnel was losing up to 34 million gallons of drinking water a day through leaks under the Hudson River. To provide a reliable water supply to New York City, repair and construction were needed. The project required emptying the tunnel quickly and overcoming continual leakage. Powerful, capable, and reliable pumps operating at great depth would be necessary. A submersible connector system would also be essential for the cable connections. The project presented many challenges, including earning proposal approval which would only be possible with absolute confidence in the equipment and process from the engineering consultants.

The solution
In order for the tunnel to be pumped empty for repairs as quickly as possible, KSB supplied powerful single-entry UPA-series borehole submersible pumps; five BSFi 586/5 + EMD NQ 200-416 with special plugged cable connections, suction shroud, and an inducer to meet lowest NPSH requirement. Benefits of these are no noise emissions, no oil lubrication of support bearings (clean water), no AC in pump houses (motor water-cooled), and service life 10 years (double suction design). Both the pump and motor units were manufactured and tested in-house by KSB. The output of each pump is around 528,344 gallons per hour at a maximum rated head of 1,050 feet. KSB made the wetted components of selected pump sets of corrosion-resistant stainless steel. The five main submersible borehole pumps were the largest sets KSB had ever produced. The drives employed 4-pole electric motors with a supply voltage of 4,160 volts.

Key success factors
KSB is a recognized market leader for large-scale projects where massive amounts of water must be moved and handled. With an extensive record of pump manufacturing, project engineering, and installation oversight, KSB offered the assurances required for this demanding, high-profile project.

Borehole Pumps from KSB