Aqueduct repair meeting draws only sparse crowd

Only a handful of people turned out for a public hearing on a $1.3 billion plan to repair and refurbish two aqueduct tunnels of the New York City water system.

Thursday’s gathering was the first of several hearings scheduled by the New York City Department of Environmental Protection.

The original Catskill Aqueduct was completed in 1916, delivering water from points north to New York City after passing through the Hudson Valley and Catskills.

The Delaware Aqueduct brings water from western reservoirs touching New York’s Southern Tier and passes through the Wawarsing-Napanoch area in Ulster County. Constructed during World War II, it is the longest tunnel in the world but has a history of major leaks, especially in Napanoch and Newburgh.

Fixing the leaks will require shutting down and draining out the Delaware tunnel system and building a permanent bypass tunnel beneath the Hudson River. The existing tube supplies half of the water for the entire system.

The work anticipates 10- to 14-day shutdowns for 2017 and 10-week shutdowns each of the following three years. The shutdown in 2020 was added to give contractors more time to prepare for the work.

Department of Environmental Protection spokesman Adam Bosch has said previously that there are about 70 upstate communities that use the Catskill and Delaware aqueducts as either a primary or secondary water source. The city has promised to provide funding for alternative water sources during the shutdowns for the town and village of New Paltz, the High Falls Water District, the town and city of Newburgh and the towns of New Windsor and Marlborough.

Before the Delaware fixes can happen, the Catskill branch must be refurbished and cleaned out to accommodate a thirsty New York City. This older aqueduct will be shut down first, for three separate 10-week stretches spanning several years — 2018, 2019, and 2020 — in order to better handle the full New York City load during the Delaware repair phase.

“When that Delaware Aqueduct gets shut down for a period of six months, we are going to have to operate the system differently than we do on a day-to-day basis,” Bosch said at the hearing Thursday.

Bosch said the Catskill tubes must be cleaned of biofilm accumulation, a harmless slime that feeds off iron and manganese in the water but sticks to the inside walls and slows down the flow, reducing capacity. Valves and other infrastructure components also will be upgraded.

“There will be teams of workers with industrial squeegees, so to speak, going in and literally scraping that aqueduct clean for 40 miles,” Bosch said. “It is a really big, complex project. These efforts amount to the biggest repair project in the history of the largest water supply in the United States.”

Chlorine dioxide and sodium hypochlorite will be added to the water to also help reduce the crud, which will be filtered downstream before reaching consumers. Officials advised that some of this material might contaminate the environment through smaller system leaks.

Some work already has been completed — in particular a connection of the two aqueducts where they cross each other in Gardiner. Delaware Shaft No. 4 is located along Route 208, just south of the Tantillo Farm.

Built 70 years ago, Shaft No. 4 features arches which were bricked over. “Engineers had the forethought that one day it might be valuable to the city, to be able to connect those two aqueducts,” Bosch noted.

“It’s only a one-way connection; at this spot we’re able to put water from the Delaware Aqueduct into the Catskill Aqueduct, which will, in the future, help us deal with episodic problems of turbidity in the Catskill system,” Bosch said. “It will also help us get some Delaware water down the Catskill Aqueduct, when we may need to do some work upstream of that Catskill connection.”

Among the local municipalities affected by this work are towns of Marlborough and Newburgh, which use the Delaware Aqueduct as a water supply; plus New Windsor, New Paltz and High Falls, which draw their municipal water from the Catskill Aqueduct. Gardiner also has a new hookup for future industrial water use.

Bosch said Lake Washington will be used to supply Newburgh during the shutdown. Last summer, the carcinogenic contaminant PFOS (perfluorooctanesulfonic acid) was discovered there. Filtration equipment is expected to be ready before the switchover. In High Falls, water will be trucked in.