Today, Mr. Patterson said, the sub-crypt flooding is much reduced. Why? His theory centers on the rise of Enclave — a 430-unit rental complex that runs the length of West 113th Street between Amsterdam Avenue and Morningside Drive. The dwelling, built from 2014 to 2016, set off protests from opponents who said the 15-story complex obscured street views of the cathedral.
With a slightly bemused expression, Mr. Patterson argued that Enclave’s foundation went down far enough to act as a subterranean barrier that diverted most of the underground flow away from the cathedral. “They solved our problem.”
We left his office to take another look at the deep vault. Crucially, Mr. Patterson knew exactly where electricians had recently installed new light switches, so we had no need for cellphone lights.
The cathedral’s cavernous subbasement consisted of big rooms, its ceiling perhaps 25 or 30 feet high. It was all poured concrete, and, unlike the crypt above, it was empty, its floor bare. That and its cavern-like size helped to explain the echoes we heard. With the lights on, the sump pumps looked less spooky, especially when Mr. Patterson started them up manually and the pit water gurgled upward.
We moved into the bigger room. The large pit was about eight or nine feet wide, and Mr. Patterson said it served as a gathering point that fed water into the pumps. The surrounding floor, like the steps, was full of watery muck. Our shoes made splish-splashy noises.
During our tour, Mr. Patterson kept pointing out features of the sub-crypt area that were either old and unused or mysterious in purpose. There were pipes, stairs and a giant shaft that went nowhere — relics from 130 years of building and rebuilding.
Now, in passing, he mentioned another relic.
At the bottom of the large gathering pool, Mr. Patterson said, was a feeder pipe, its source unknown. “It’s another pipe from nowhere,” he said, his voice reverberating. “But it was put there intentionally to get water into that pit.”
