Hi Bob:

We've used a pig to help on water main problems, but not a force main.  It worked, but we needed to create a pig entry point that was easy to access the main....valves were essential.  The foam pigs provide great options.

A challenge I have seen is that we use VFD's to control pump cycling.  In doing so, we ignore the minimum velocities of the force main.  Perhaps at night time, it's worth allowing the wet well to build-up...then use multiple pumps to create a scouring velocity.

Just a few thougths.

Dean Falkner