GREENPOINT — The city is floating a proposal to dig a massive $910 million underground tunnel near the Newtown Creek as a way to trap sewage runoff from spewing into the already polluted waterway.
The pitch is one of several different options laid out as by the city's Department of Environmental Protection, that comes as part of its court-mandated plan to clean up local waterways.
The tunnel could curve up to two and half miles, 250 feet below ground, near the banks of the Newtown Creek linking up outfalls and feeding that water directly to the Newtown Creek Waste Water Treatment Facility to be cleaned.
(Here are two of the three proposed routes for the tunnel.)
The rock tunnel would vary in width, length and price, according to different estimates about how much wastewater it would divert.
The cheapest project would cost $360 million for a 16-foot wide tunnel though it would only catch 25 percent of raw sewage runoff. The most expensive option would cost $910 million to build and would have to be 40-feet-wide, though it would capture 100 percent of the excess sewage.
While the tunnel is one of the pricier options to keep waters clean, the city also outlined cheaper possibilities, like building underground storage tanks, more green infrastructure to capture and hold storm water when it rains and constructing new pumping stations.
In June, the city takes those plans to the state's Department of Environmental Conservation and together they'll agree which of the varying plans to choose.
As it stands, during most rainstorms, the Newtown Creek transforms into a fecal hotspot.
A total of around 965 million gallons of untreated waste water flow into the waterway each year during around 40 storms, according to models from the city's Department of Environmental Protection. The sewage spew is known as Combined Sewage Overflow or CSO.
The current sewer system becomes overwhelmed with the combination of rainwater and wastewater from toilets and sinks, backing up in the existing underground pipes so that it shoots into the river when it reaches certain outflow points.
Clean water advocate Christopher Swain who swam the length of the creek on a slightly rainy day in 2015, described human waste bobbing beside him and environmental advocates have captured videos of brown goo gushing into the creek.
In 2012, the city and state came to a court-mandated agreement that the city would invest in long-term plans for 10 polluted waterways to keep sewage from waterways in accordance with the federal Clean Water Act.
So far the city has already shelled out $4.2 billion in decreasing sewage overflows across across the city and is expected to pay $20.7 billion in the next seven years, according to DEP officials.
