Not certain, but I don't think "pigs" work well in eight inch feeder lines flowing gas.  Maybe a pipeline engineer could chime in on that. 
Just thinking about the muck and sludge that must be in that line after almost fifty years in salt water.  
If the AGDC "big" Nikiski gasline route is approved it will go under the inlet for thirty miles.  If FERC decides it would be better for Alaska`s big line to go to Valdez, the need for all that long underwater pipe run is negated, and we stay on a TAPS right-of-way that is already in place with a road and cantonment areas beside it for most of the way.  We should know FERC`s answer on location by the end of this year.  It`s mandatory to offer FERC an alternative route for them to study.  Lucky for Alaskans...