Bringing back the water

New York City’s first underground water filtration plant provides safe drinking water to New Yorkers

The Croton Water Filtration Plant can treat between 20 to 30 percent of New York city’s daily water usage, but most residents never see the plant — it’s built completely underneath the Mosholu Golf Course in The Bronx. Completed in 2015, the facility reintroduced the Croton water system — the city’s oldest system, which went into use in 1842, and provides redundancy to New York City’s drinking water supply system.

Bringing Croton water back

We worked with the New York City Department of Environmental Protection to provide construction management services for the city’s first water filtration plant. With the capacity to deliver 290 million gallons per day, this $3.2 billion facility was a consent order driven project.

We provided engineering design, environmental services and design services during construction as part of a joint venture. The new 400,000 square foot plant was the first water filtration plant located in NYC and can provide roughly 30 percent of the city’s daily water needs.

Tunneling expertise

The project required the drilling, explosive blasting and excavation of 250,000 cubic yards of soil and 950,000 cubic yards of rock. Ultimately, the tunnel system was completed at a final depth of 100 feet below the surface. An 850-foot tunnel connects to the New Croton Aqueduct for the raw water feed and two 4,000-foot tunnels from the Croton Water Filtration Plant to the Jerome Park Reservoir. The tunnel work also included a 100-foot-deep shaft to provide access for required future maintenance.

Equity in the water supply

The new Croton Water Filtration Plant provides filtration and disinfection of water from Croton’s supply of 12 reservoirs and three controlled lakes located 30 miles north of New York City. The Croton Water Filtration Plant was required to allow the city to use Croton water that meets current drinking water standards and was built for redundancy.