Colin tells us that for the last few weeks, he and his wife hear a near-constant rumbling around their Phinney Ridge neighborhood of North 57th Street and Greenwood Avenue North. He says it’s a low frequency that sounds like an approaching helicopter but never gets any louder. It’s enough to rattle his pots and sometimes his windows. He says there is some road work nearby but the rumbling happens even when that work is stopped. It seems to only happen during the day.
Does anybody have any ideas what it might be?