Unless you live in Failsworth or REALLY close then this isn't really worth the travel to see. It's a fairly short culvert on the Hole Bottom Brook, which was formerly a tributary of the Moston Brook, of
Processor &
The Works fame, but now outfalls into the Rochdale canal. The first 60 metres or so from the outfall heading upstream is a red brick railway culvert, but is so badly silted that it's just easier to get in via a cover upstream.
Following the old railway culvert the construction changes to corrugated metal pipe, at around 5'8" high and relatively feature less it's not an exciting drain, but it's another buried and little known Manchester waterway that's still down there.
Two hundred metres in the pipe shrinks down to a painfully small stooping height brick tunnel, I ventured a little way down it but fear it goes on and on like this and so I left that there.
The most notable thing about this spot is that there was always a faint smell of fuel, I've experienced that previously, usually as a result of surface run off/spillage. Heading downstream however as I hit the silted section toward the outfall I noticed a black/brown tar like gunk was actually coming up out of the silt as you lifted your foot out of it and the smell suddenly increased markedly, at this point I needed no further prompting to make a swift exit. Heading for the outfall was not an option due to the silt being above knee deep, so I shot back upstream to the cover.
At no point while I was down there did my gas meter register anything, and I have the tolerances set super low, also I felt fine the whole time and I use an intrinsically safe torch for navigation so that negates any explosive risk in that regard. None the less hanging around in rather confined spaces with fumes and oily gunk bubbling from the floor is definitely not a wise move, and so I did not.
Here's the TWO whole pictures I took.
A manhole shaft drops into the tunnel centrally via a funky curved ladder
The upstream shrinking point, also my entry/exit cover point.
JD