Connecticut Company streetcars were a little before my time -- I'm an old guy but not that old! -- but I can make a reasonable guess. ConnCo had a line originating at Exchange Place in downtown Waterbury that ran out Chase Avenue and Homer Street to Waterville and ultimately to Thomaston, and there was a trolley spur off Homer Street into what was listed on maps as the Chase Mill freight yard. I'd guess that's where your grade was. The line was converted to buses in 1937. As to whether the NH picked up any of that yard/spur trackage, which would have been adjacent to the railroad, the RMNE guys would know that detail better than me.