The Delaware Aqueduct, completed in 1944, is the longest tunnel in the world. This 85 mile stretch of steel and concrete transports 50% of New York City’s water supply downstate from several reservoirs in the Delaware Watershed. In 1991, a major leak was discovered near Newburgh, but the Department of Environmental Protection did not release a remediation plan until 2010. In the interim, the DEP tested and surveyed the aqueduct, determining that between 15 million and 35 million gallons of water were being lost each day. The leak was caused by the unstable geologic features through which this segment of the tunnel passed under the Hudson River. The tunnels were bored through faulted limestone, which did not provide enough support. Thus, cracks developed and leaks sprung.
Source: Upstater Magazine
The DEP’s 2010 repair plan was to construct a bypass tunnel. Since it still must travel under the Hudson River through unstable limestone, the 2.5 mile bypass is to be lined with 9,200 linear feet of steel, while the original tunnel was only lined with 1,900. Between 2013 and 2016, the shafts on each side of the tunnel were completed, and a high-tech boring machine was constructed. Just this year, the boring machine (named after Nora Stanton Blatch Deforest Barney, the first woman in the U.S. to earn an engineering degree) and 40-foot sections of steel liner were delivered to the site where the project will begin in Newburgh. Boring the hole for the bypass tunnel is projected to take two years, during which the leaking segment of the aqueduct will remain in use. After completion, it will take 6 to 8 months to shut down the current aqueduct, drain it, connect the bypass, and get everything back up and running. The entire project was originally scheduled for completion in 2019, but according to the DEP, the tunnel alone will not be finished until 2022. If all goes as currently scheduled, the earliest the water will flow through the bypass tunnel and into the city is 2023.
Because the Delaware Aqueduct delivers half of New York City’s water supply, a complete shutdown for several months poses issues. To ensure that the city has access to sufficient, reliable water during the shutdown, the Water for the Future program was developed. Under this initiative, the Catskill Aqueduct was to be repaired starting in 2016 to increase capacity by 30 to 40 million gallons per day. The project, now scheduled to begin in 2018, requires three separate 10-week shutdowns, and is projected to be completed by 2020. Rehabilitating the Queens Groundwater System is also on Water for the Future’s agenda. This water source is expected to provide over 30mgd, but as of June 2017, the only progress the DEP has made was holding public meetings regarding the intent to prepare an Environmental Impact Statement. The proposal was not well received by Long Island officials, who are concerned that re-opening these wells may damage aquifers that provide water to Nassau and Suffolk counties.
The Water for the Future program includes plans for a filtration plant, making water from the Croton Watershed available in New York City. Construction of the Croton Water Filtration Plant was completed in 2015, and it has supplied water to parts of Manhattan and the Bronx ever since. This extra water will be crucial during the period when the Delaware Aqueduct water supply is cut off. Normally, the Croton Watershed provides about 10% of the city’s water daily. The Department of Environmental Conservation estimates that in times of drought or emergency, in this case the Delaware Aqueduct shutdown, it is capable of providing 30% of the city’s water. Lastly, the DEP has been implementing conservation initiatives in the city, so New Yorkers become dependent on less water. The 2013 Water Demand Management Plan, created in light of the Water for the Future program, details the implementation of water management projects throughout New York City. These 21 initiatives include municipal, residential, and non-residential water efficiency; water distribution optimization, water supply shortage management, and upstate water conservation. Completion is aimed for 2021.
Data Source: NYC Open Data
Despite these efforts to prepare for the shutdown, it is questionable whether New York City is ready for this project. Although water consumption per capita in New York City has dropped over the years (30% since the 1980s), the population has increased. Since the Water Demand Management Plan was implemented in 2013, the city has seen slight fluctuations in daily consumption, and no substantial reduction, as shown in the accompanying graph. Mayor de Blasio has a track record of postponing work on water-related projects, such that budgets can be realigned to keep water rates down. However, without improved water infrastructure New York City will be very ill-equipped in the event of a drought or natural disaster. It is crucial that projects and conservation initiatives are brought to fruition, because at its current rate of consumption, New York City is not prepared for the Delaware Aqueduct shutdown. Ideally, water consumption must be cut by 40% before the shutdown occurs. We are in a precarious position, in which we can afford neither to push the completion date of the repairs farther out, nor to begin the project without proper conservation methods and supplementary water sources secured. It is imperative that action is taken soon to ensure New Yorkers have a reliable water source for years to come.