As New York City’s Department of Environmental Protection (DEP) continues to work on cleaning biofilm from the inside of the Catskills Aqueduct, replacing ancient valves and repairig leaks in the northern 74 miles of the water supply system, there are times when it must cut off access to communities that purchase that water. While New Paltz residents are under a water-use advisory, a team of highly skilled divers is preparing to plunge more than 300 feet into a section of the Catskills Aqueduct to remove an old valve, conduct an inspection, and install a new plug.
Both the water advisory and the technical dive are part of the ongoing $158-million project to rehabilitate the 92-mile-long, century-old aqueduct created to supply water from upstate to New York City-dwellers in 1915.
“Whenever we’re notified that there will be a span of time when we cannot access water from the Catskills Aqueduct, we put our residents under advisory,” said Village of New Paltz mayor Tim Rogers. Sixty percent of New Paltz water is supplied by the aqueduct and the rest from our four reservoirs on Mountain Rest Road.
“Whenever they do repair work, we make sure to have our four reservoirs full, pumping extra water from the aqueduct into our largest reservoir and then providing the community with an advisory that this would not be the best time to utilize water unnecessarily,” Rogers explained. “It’s just extra padding in case of an emergency like a water-main break or a structure fire. We want to make sure we have more than enough water to cover our average daily use, as well as unforeseen emergencies.”
Creation of the aqueduct was a herculean achievement, one that has faithfully served the growing metropolis of New York City for the past 105 years. It began with the flooding of several rural communities and towns in the Catskills region and excavation of a tunnel that is much larger than people are aware. The aqueduct is gravity-fed, and in some places the tunnel drops down precipitously. Adam Bosch, director of Public Affairs for the DEP, has said that this deep dive was “the most technically complex effort to rehabilitate the Catskills Aqueduct since it first began delivering water in 1915.”
“The dive that is happening now is a particularly unique part of the project,” Bosch explained, “being performed inside a chamber that has the ability to remove water from the Catskills Aqueduct by putting it into the Wallkill River.” He said that there were several such chambers on the aqueduct, “giving it the ability to empty out into local rivers and creeks in Ulster, Orange, Putnam and Westchester counties on its way toward the City.”
Trained divers are doing what is known as a “saturation dive.” Because this task requires them to dive into water sometimes more than 300 feet deep, their bodies must first be acclimated to withstand that pressure. “That pressure is about ten times greater than the regular atmospheric pressure that our bodies feel,” said Bosch. “The divers are compressed inside a special chamber, and then they get transported to the depth of the work inside a diving bell.”
“Once they are finished with their shift,” he continued, “they are brought back to the surface in the diving bell and will live in a pressurized chamber to remain at the pressure of the dive.” These divers will continue to remain “compressed” for approximately three weeks. “By being compressed and decompressed only once, it prevents the divers from getting decompression sickness,” said Bosch.
Although a second dive will be occurring at a different location, the divers will remain in compression while they are in transit between the two spots. At the first location, near the Wallkill River, Bosch said that the crew will be removing a valve and installing a specially designed mechanical plug in place of that valve, and using a remotely operated vehicle to perform an inspection of this part of the aqueduct.
Mayor Rogers was happy to report that the village has been awarded its “largest-ever grant,” upwards of $3 million, to help address its turbid-drinking-water problems. “Several of our approximately 100-year-old tuberculated water mains that are prone to creating turbid [brown] water when jostled will be replaced,” he promised. The turbidity happens when the village government is performing routine work on the system, like flushing hydrants. Sometimes nearby construction can shake the ground.
Although the brown water is a common color-symptom from older cast-iron water mains, “We can do better,” Rogers said. Previously, municipal officials would advise residents to run their taps until the water cleared. The award from the New York State Environmental Facilities Corporation will “provide 60 percent of the funding for our 18,000-linear-feet project” slated to include new water lines for North Chestnut Street, North Manheim Boulevard, Prospect Street, Huguenot Street and a wooded area near Canaan Road parallel to Mountain Rest Road.
The village will borrow the other two million dollars for the five-million-dollar project, said the mayor.