I took a rough measurement, looked to be about 8-12 inches deep. It also looked like there was a wide, hollow area under the hole that expand beyond its 4" diameter surface size. It was like there wasn't any ground under there anymore.
A. More than 6” deep
A. 18 Sylvester Ave
A. The hole is on the even side of the road, between 18 and 20 Sylvester, and across from 19. It's about 4 inches in diameter and mostly circular.