The Maintenance Department at our local wastewater treatment facility does not allow the use of insertion riser rings for minor manhole adjustments on roadway resurfacing projects (throughout their collection system). Their objections are threefold: The rings tend to pop loose when manhole covers are removed, they're not watertight [their sewer system is plagued by I/I issues] and, they can become dislodged by snow plowing, after a number of seasonal freeze/thaw cycles.

I've found plenty of on-line sources advocating the use of these rings as the greatest thing since sliced bread but, does anyone out there share any of the above (or other) concerns?

Thanks!