I have looked at your photo and it is certainly not an ice house much too small, some drainage levels certainly are that small.
A clue would be to extrapolate its course above ground and see whats there, although you might have to cover some distance. I appreciate that you dont want to put the location on a public forum, but drawing a straight line corresponding to its direction on a large scale map, particularly and old map, could be useful.
Drainage adit or old water course suggests itself. Exploration I think wise to take a gas meter, I agree, a job for someone who understands these things.
Wheres Stu?
EDITED because postings interleaved
Morlock could be on the money, but warning about gas or bad air relevant, my feeling just by looking at it.
My avatar is a poor likeness.