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The Department of Environmental Facilities workers have spent this scorching day hosing and scooping chlorine into an open manhole adjacent to Horan's Landing where .
Just what the quantity is is uncertain, and Superintendent of Maintenance Joe LaBella on the site directed me to the Commissioner's office to get a sense of the bigger picture.
DEF Commissioner Tom Lauro further described the mechanics of our sewage system in Tarrytown and Sleepy Hollow and what precipiated such a drastic, but not unheard of, result.
Lauro said the problem, which has happened several times before, is with the 30-inch diameter pressurized “force main” line that runs from the Tarrytown Pump Station uphill roughly along Church Street, crosses Broadway, and connects with the Aqueduct until it takes a left at Route 119, and follows the Saw Mill Parkway to its next pump station stop in North Yonkers.
It's this main line, part of which runs inside the Old Croton Aqueduct, which experienced a break Wednesday. The pipe, he said, developed a hole on the top under the parking lot on Leroy Avenue just off of Route 9 and as a result, about 500,000 gallons of sewage ran inside the aqueduct, which no longer carries water but telecommunications lines, starting around 10 a.m. Lauro said the telecommunications lines would not be damaged because they are housed in their own pipes inside the aqueduct. The foreign sewage in the aqueduct flowed to Yonkers where it exited out a storm drain.
Wednesday night, workers shut down the pumps to drain and work on the damaged pipe. They have been tearing up this parking lot, pulling bricks off the century-old aqueduct, cutting out a long section of the old pipe and laying in new. The necessary bypass to do this resulted in an overflow in the gravity-run system usually connecting houses to the pump station by way of going naturally downhill to the easiest outlet, which happens now to be at Horan's Landing in Sleepy Hollow. Here, the workers noted the outflow beginning, he said, at 7:15 a.m. Thursday morning which remains ongoing as of Thursday afternoon.
Because the discharge is “ongoing” until the pipe is fixed and the bypass restarted, there are no figures available on the actual amount of sewage entering the waterway verses the “millions of gallons” first offered in the Health Department alert.
Lauro said the pump station moves 2.7 million gallons in an average day, so you can figure it is indeed in the millions after a full day.
The County Health Department would come to Horan's Landing Thursday at 3 p.m. to take water samples. They will have the results 24 hours later and then report on whether the water advisory can be lifted or not. Or they might need to take another sample at that point, said Lauro.
Contrary to the initial report that said the water advisory was in effect from Croton Point Park to “all points south,” Lauro said the water was unaffected south of Yonkers, where a smaller but negligible amount of sewage is also being discharged as a result of the Tarrytown break.
“There is no impact south of Yonkers,” he said. He noted that the Ironman race involving swimming in the Hudson in NYC this weekend “should not be affected.”
Lauro said the water advisory would likely be lifted shortly after the discharge stopped since “there's just so much water in the Hudson.” Lauro also addressed those who expressed concerns about living in closest vicinity to this discharge site, specifying that it's an advisory against being in the water itself not near it.
For those wondering how old is our old system, the main force line dates to the 1970s, Lauro said. Which is “not old-old” but “due to be replaced.” The county is actually in design phase to replace that line, which would of course be quite an undertaking involving open excavation and drilling something tunnel-like along its long route.
Lauro agreed people don't know what happens when they flush their toilets until something like this happens. “Out of sight, out of mind,” he said.
