Major Influent Weir Rehab
Work is continuing on the Catskill Influent Weir (CIW), the structure where the Catskill Aqueduct releases its water into Kensico Reservoir, and, once completed, it should look more like it did when the aqueduct was first put into service in 1915.
The historic photo shows a smooth, clean-looking formation of concrete. More than a century later, there has been some deterioration of the 12 piers supporting the aqueduct’s wall. With more water than usual likely flowing down the Catskill Aqueduct next year, repairing and reinforcing parts of the CIW is one of the most significant projects during the fourth and final year of our ongoing work to rehabilitate the aqueduct.
The CIW is a small section of the 92-mile-long Catskill Aqueduct, which carries drinking water from Ashokan Reservoir in Ulster County to Hillview Reservoir in Yonkers. The repair and rehabilitation project, which started with the first 10-week shutdown in 2018, is focused on the 74 miles running from Ashokan to Kensico. The work on the aqueduct is key to preparing for the planned shutdown of the Delaware Aqueduct in 2022, as part of the Delaware Aqueduct Bypass Tunnel project.
This year’s shutdown of the Catskill Aqueduct is five weeks longer than the others partly because of the complexity of the work at the CIW. The weir is a section of the aqueduct with openings in its side. Water flows down the aqueduct and out into Kensico through these gaps. Piers sit on the outside of the aqueduct and, like the studs in your home’s walls, are there for support. Importantly, the piers cannot be replaced in order as working on adjacent piers would threaten their support function.
Once the aqueduct is turned off at Ashokan, water can back up in the aqueduct and many millions of gallons were pumped out or released through other means over five days. Contractors built 12, wall-sized wood panels backed by steel. Using a 45-ton crane, each panel was hoisted into place in front of the weir opening. Once they were connected and sealed, pumps lowered the water level between this bulkhead and the weir so workers could have a dry area to work.
