Cochituate Aqueduct (Newton: house, dangerous, safety)

[Arkazex]

Hello everyone,
Recently, I was walking down the portion of the Cochituate Aqueduct near my house when I tripped over a small granite ledge. I brushed away some of the dirt on top and found that it was a heavy iron door set into a granite collar. My friend and I lifted the door free of the cakes of dirt, and after digging away some of the dirt found a thin cement layer, with several holes in it. Upon poking the dirt out of one of these holes, we were blasted with the worst smell either of us had ever seen, resulting in both of us nearly throwing up.
I was wondering if anyone here could provide some insight into what this shaft is. I read somewhere that parts of the aqueduct have been transformed into sewers, but there are two sewer lines on either side of the aqueduct (I've seen into both of them) and the depth of the ditch was about 25' deep, plus another 5' down the shaft before we reached the smell.
Thanks to anyone who replies,
- Ark

[Parsec]

I can't think of anything else that would cause such a putrid smell though. Parts of the aqueduct is now owned by Newton and is used for sewer lines.

[495neighbor]

Not a great idea to do this kind of exploring for your own safety and for the reason you were trespassing on government property. For all you know, your adventure could have resulted in your being pulled into a sewer system when you opened the Pandora's box. I think it might be wise to take up a less dangerous sport like sky diving or snow boarding in the near future.